1-Thermodynamics of Zn_NH_3_NH_4Cl_H_2O system

第42 卷第 12 期2023 年12 月Vol.42 No.121580~1587分析测试学报FENXI CESHI XUEBAO（Journal of Instrumental Analysis）均相合成多重选择性的新型两亲性C22高效液相色谱固定相范二乐1，蒋星宇1，张加栋1*，张明亮2，韩海峰1，2，张大兵1，2，陈义1，3（1．淮阴工学院矿盐资源深度利用技术国家地方联合工程研究中心，高端矿盐功能材料智能制备国际合作联合实验室，江苏淮安223003；2．江苏汉邦科技股份有限公司，江苏淮安223000；3．中国科学院化学研究所活体分析化学科学院重点实验室，北京100190）摘要：为解决高效液相色谱（HPLC）固定相非均相合成中产物多变和重现性差等问题，该文采用均相合成新方法，制备了既含有二十二碳烷基（C22）、又嵌入脲（U）和/或酰胺（A）强极性基团的两种新型两亲性色谱固定相C22-A和C22-A/U。

通过元素分析、核磁等手段，证实制备的两种新型固定相含有碳、氮元素，且碳氮元素比例符合理论值，表明酰胺和脲基极性基团成功键合到硅胶上。

通过对多种样品进行色谱分离分析，对两种新型固定相的载体残余硅羟基屏蔽作用、疏水选择性、形状选择性和亲水性等多种性质进行了考察，证实两种新型固定相不但具备作为反相液相色谱（RPLC）的性能，同时也具备亲水相互作用色谱（HILIC）的性能。

相较于C18固定相，C22-A和C22-A/U具有更好的形状选择性，双重嵌入的极性基团极大地降低了固定相硅羟基活性。

将C22-A和C22-A/U两种固定相应用于几种碱性化合物、雌醇（酮）类化合物的分离，C22固定相在一定程度上解决了传统C18固定相上碱性化合物分离拖尾严重或保留不足的问题，成功实现了对雌醇（酮）类化合物的分离。

关键词：色谱固定相；两亲性；均相合成；药物分析；液相色谱中图分类号：O657.7；R914.1文献标识码：A 文章编号：1004-4957（2023）12-1580-08 Homogeneous Synthesis of Novel Amphiphilic C22 StationaryPhases with Multiple SelectivityFAN Er-le1，JIANG Xing-yu1，ZHANG Jia-dong1*，ZHANG Ming-liang2，HAN Hai-feng1，2，ZHANG Da-bing1，2，CHEN Yi1，3（1．International Cooperation Joint Laboratory for Intelligent Preparation of High-end Functional Mineral SaltMaterials，National & Local Joint Engineering Research Center for Mineral Salt Deep Utilization，Huaiyin Instituteof Technology，Huai’an　223003，China；2．Jiangsu Hanbon Science & Technology Co.Ltd.，Huai’an　223000，China；3．CAS Key Laboratory of Analytical Chemistry for Living Biosystems，Instituteof Chemistry，Chinese Academy of Sciences，Beijing　100190，China）Abstract：In order to solve the variable and irreproducible issues of heterogeneously synthesized chromatographic stationary phases，a new method of homogeneous synthesis was established and used to prepare two newly designed amphiphilic stationary phases，C22-A and C22-A/U，where C22 denotes a long docosyl terminal while U and A denote the strong polar insertions of urea and am⁃ide groups at the initial end，respectively. By the means of elemental analysis and nuclear magnetic spectrum，the two new stationary phases contain nitrogen elements，and the ratio of carbon and nitro⁃gen elements accords with the theoretical value，indicating that the amide and urea-based polar groups are successfully bonded to silica gel. Through the chromatographic separation and analysis of the standard sample and the real sample，the shielding effect on upported silicon hydroxyl，hydro⁃phobic selectivity，shape selectivity and hydrophilicity of the two new stationary phases were investi⁃gated.It is confirmed that the two new stationary phases have amphiphilic properties as reversed-phase liquid chromatography（RPLC）and hydrophilic interaction chromatography（HILIC）.Com⁃pared with C18 stationary phases，C22-A and C22-A/U own better shape selectivity，and the dou⁃doi：10.19969/j.fxcsxb.23072402收稿日期：2023－07－24；修回日期：2023－09－15基金项目：国家自然科学基金重点项目（22134007）∗通讯作者：张加栋，博士，副教授，研究方向：化学与生物传感、色谱分离分析等，E-mail：jiadongzhang@1581第 12 期范二乐等：均相合成多重选择性的新型两亲性C22高效液相色谱固定相ble embedded polar groups greatly reduce the silica hydroxyl activity of the stationary phase. C22-A and C22-A/U were used for the separation of several alkaline compounds and estrone（ketone） com⁃pounds. The C22 stationary phase solved the problem of serious tailing or insufficient retention of al⁃kaline compounds in the traditional C18 alkyl stationary phase，and successfully realized the separa⁃tion of estrone（ketone） compounds.Key words：chromatographic stationary phase；amphiphilicity；homogeneous synthesis；drug analysis；liquid chromatography色谱固定相的性质决定了保留机理、分离效率以及适合的分离对象［1-2］。

五氯乙烷沸点概述说明以及解释1. 引言1.1 概述本篇文章旨在探讨五氯乙烷的沸点特性，并对其进行深入的分析和解释。

五氯乙烷是一种常见的有机化合物，其性质和应用领域备受关注。

了解其沸点的测定方法、范围以及影响因素，对于加深我们对五氯乙烷的认识具有重要意义。

1.2 文章结构本文共分为四个部分进行论述，即引言、正文、结果与讨论以及结论。

其中，正文部分介绍了五氯乙烷的性质并阐述了液体沸点与气体沸点的概念；随后详细解析了测定五氯乙烷沸点的方法。

在结果与讨论部分，我们将对五氯乙烷的沸点范围及其影响因素进行解析，并说明不同环境条件下其沸点变化情况。

最后，我们将比较五氯乙烷与其他物质的沸点，并展望它在应用领域中可能发挥的作用。

1.3 目的本文主要目的有三个方面：首先，通过介绍五氯乙烷的性质，使读者对该化合物有一个全面的了解；其次，阐述液体沸点与气体沸点的概念，帮助读者理解五氯乙烷在不同状态下发生相变的原理；最后，探究测定五氯乙烷沸点的方法，并分析其沸点范围及受影响因素，以期为相关实际应用提供指导和有价值的评价。

2. 正文：2.1 五氯乙烷的性质介绍五氯乙烷是一种有机化合物，分子式为C2Cl5H和分子量为201.3 g/mol。

它是无色液体，在常温下具有刺激性气味。

五氯乙烷主要用作工业溶剂和农药成分，具有较高的挥发性和不容易挥发的特点。

2.2 液体沸点与气体沸点的概念液体沸点是指在给定压力下，液体开始转变为气体状态（也称为饱和蒸汽）的温度。

而气体沸点则是指在标准大气压下，液体开始转变为气体状态的温度。

2.3 五氯乙烷的沸点测定方法五氯乙烷的沸点可以通过实验测定来确定。

一个常用的方法是采用常压蒸馏法。

该方法中，将样品加入装有热源的容器中，在恒定压力下进行加热。

当样品温度上升时，在某一温度达到液体与饱和蒸汽平衡时，开始观察到液体汽化，此时该温度即为五氯乙烷的沸点。

此外，还可以使用气相色谱法进行沸点测定。

该方法利用了不同物质在不同温度下的沸点差异，在分析仪器中通过气相色谱柱将五氯乙烷样品加热至其开始挥发的温度，记录并分析挥发物质的特征峰，从而确定沸点。

Standard Thermodynamic ValuesFormula State of Matter Enthalpy(kJ/mol)Entropy (Jmol/K)Gibbs Free Energy(kJ/mol)(NH4)2O (l) -430.70096267.52496 -267.10656 (NH4)2SiF6 (shexagonal) -2681.69296280.24432 -2365.54992 (NH4)2SO4 (s) -1180.85032220.0784 -901.90304 Ag (s) 042.55128 0 Ag (g) 284.55384172.887064245.68448 Ag+1 (aq) 105.57905672.67608 77.123672 Ag2 (g) 409.99016257.02312 358.778 Ag2C2O4 (s) -673.2056209.2 -584.0864 Ag2CO3 (s) -505.8456167.36 -436.8096 Ag2CrO4 (s) -731.73976217.568 -641.8256 Ag2MoO4 (s) -840.5656213.384 -748.0992 Ag2O (s) -31.04528121.336 -11.21312 Ag2O2 (s) -24.2672117.152 27.6144 Ag2O3 (s) 33.8904100.416 121.336 Ag2S (sbeta) -29.41352150.624 -39.45512 Ag2S (s alpha orthorhombic) -32.59336144.01328 -40.66848 Ag2Se (s) -37.656150.70768 -44.3504 Ag2SeO3 (s) -365.2632230.12 -304.1768 Ag2SeO4 (s) -420.492248.5296 -334.3016 Ag2SO3 (s) -490.7832158.1552 -411.2872 Ag2SO4 (s) -715.8824200.4136 -618.47888 Ag2Te (s) -37.2376154.808 43.0952 AgBr (s) -100.37416107.1104 -96.90144 AgBrO3 (s) -27.196152.716 54.392 AgCl (s) -127.0680896.232-109.804896 AgClO2 (s) 8.7864134.55744 75.7304 AgCN (s) 146.0216107.19408 156.9 AgF•2H2O (s) -800.8176174.8912 -671.1136 AgI (s) -61.83952115.4784-66.19088 AgIO3 (s) -171.1256149.3688 -93.7216 AgN3 (s) 308.7792104.1816 376.1416 AgNO2 (s) -45.06168128.19776 19.07904 AgNO3 (s) -124.39032140.91712 -33.472 AgO (s) -11.4223257.78104 14.2256 AgOCN (s) -95.3952121.336 -58.1576 AgReO4 (s) -736.384153.1344 -635.5496 AgSCN (s) 87.864130.9592 101.37832 Al (s) 028.32568 0 Al (l) 8.6608835.229286.61072 Al (g) 326.352164.4312285.7672 Al(BH4)3 (l) -16.3176289.1144 144.7664 Al(BH4)3 (g) 12.552379.0704 146.44 Al(CH3)3 (l) -136.3984209.4092 -10.0416Al(NO3)3•6H2O (s) -2850.47552467.7712 -2203.88016 Al(NO3)3•9H2O (s) -3757.06464569.024 -2929.6368 Al(OH)3 (s) -1284.48871.128 -1305.8264 Al+3 (aq) -531.368-321.7496 -485.344 Al2(CH3)6 (g) -230.91496524.6736 -9.79056 Al2(SO4)3 (s) -3435.064239.3248 -3506.6104 Al2Br6 (g) -1020.896547.2672 -947.2576 Al2Cl6 (g) -1295.3664475.5116 -1220.8912 Al2F6 (g) -2631.736387.02 -2539.688 Al2I6 (g) -506.264584.0864 -560.656 Al2O (g) -131.3776259.408 -161.084 Al2O3 (l) -1581.133689.57944-1499.25272-1656.86459.8312 -1562.724 gamma-corundum)Al2O3 (salpha-corundum)-1675.273650.91928 -1581.9704 Al2O3 (sgibbsite) -2562.7140.20584 -2287.3928 Al2O3•3H2O (sboehmite) -1974.84896.8596 -1825.4792 Al2O3•H2O (sAl2O3•H2O (sdiaspore) -1999.95270.54224 -1840.96halloysite) -4079.8184203.3424 -3759.324 Al2Si2O7•2H2O (skaolinite) -4098.6464202.924 -3778.152 Al2Si2O7•2H2O (sandalusite) -2591.98893.3032 -2444.7112 Al2SiO5 (skyanite) -2596.17283.80552 -2443.8744 Al2SiO5 (ssillimanite) -2593.243296.19016 -2442.6192 Al2SiO5 (sAl4C3 (s) -207.27536104.6 -238.44616 Al4C3 (g) -215.894489.1192 -203.3424 Al6BeO10 (l) -5299.4544314.88784 -5034.1888 Al6BeO10 (s) -5624.1328175.56064 -5317.4456 mullite) -6819.92274.8888 -6443.36 Al6Si2O13 (sAlBO2 (g) -541.4096269.4496 -550.6144 AlBr3 (s) -511.11744180.24672 -488.31464 AlBr3 (l) -501.20136206.4804 -486.26448 AlBr3 (g) -410.8688349.07112 -438.4832 AlC (g) 689.5232223.34192 633.0392 AlCl (g) -51.4632227.86064 -77.8224 AlCl2 (g) -288.696288.2776 -299.5744 AlCl3 (g) -584.5048314.30208 -570.07 AlCl3 (s) -705.6316109.28608 -630.06856 AlCl3 (l) -674.79552172.92472 -618.186 AlCl3•6H2O (s) -2691.5672376.56 -2269.4016 AlF (g) -265.2656215.0576 -290.788 AlF2 (g) -732.2263.1736 -740.568 AlF3 (s) -1510.42466.48376 -1430.928-1192.8584 AlF3 (g) -1209.176276.7716AlF3•3H2O (s) -2297.4344209.2 -2051.8336 AlH (g) 259.24064187.77792 231.166 AlI3 (l) -297.064219.66 -301.248 AlI3 (g) -205.016363.1712 -251.04AlI3 (s) -309.616189.5352 -305.432-287.0224 AlN (s) -317.98420.16688AlN (g) 435.136211.7104 410.032 AlO (g) 83.68218.27928 57.7392 AlOCl (s) -793.286454.392 -737.26264 AlOCl (g) -348.1088248.82248 -350.2008 AlOF (g) -586.5968234.26216 -587.0152 AlOH (g) -179.912216.3128 -184.096 AlPO4 (sberlinite) -1692.009690.7928 -1601.2168 AlS (g) 200.832230.49656 150.2056 Ar (g) 0154.732688 0 Au (g) 366.1180.39316 326.352 Au (s) 047.40472 0 Au(CN)2-1 (aq) 242.2536171.544 285.7672 AuBr4-1 (aq) -191.6272335.9752 -167.36 AuCl4-1 (aq) -322.168266.9392 -237.31648 AuH (g) 294.972211.045144 265.684518.816 B (g) 562.748153.3436B (s) 0 5.8576 0 B(CH3)3 (l) -143.0928238.9064 -32.2168 B(CH3)3 (g) -124.2648314.6368 -35.9824 B(OH)4-1 (aq) -1344.02632102.508 -1153.3196 B2 (g) 830.524201.79432 774.04 B2Cl4 (l) -523262.3368 -464.8424 B2H6 (g) 35.564232.0028 86.6088 B2O2 (g) -454.8008242.37912 -462.332 B2O3 (g) -843.78728279.7004 -831.9884 amorphous) -1254.5305677.8224 -1182.3984 B2O3 (sB2O3 (s) -1272.772853.9736 -1193.6952 B3N3H6 (l) -540.9912199.5768 -392.79392 B4C (s) -71.12827.11232 -71.128 B5H9 (l) 42.6768184.22152 171.66952 Ba (s) 062.3416 0146.8584 Ba (g) 179.0752169.99592Ba (l) 4.9789666.7348 3.84928 Ba(BrO3)2 (s) -752.65976242.672 -577.392 Ba(BrO3)2•H2O (s) -1054.7864292.4616 -824.62456 Ba(ClO3)2 (s) -680.3184196.648 -531.368 Ba(ClO4)2•3H2O (s) -1691.5912393.296 -1270.6808 Ba(IO3)2 (s) -1027.172249.3664 -864.8328 Ba(IO3)2•H2O (s) -1322.144297.064 -1104.1576 Ba(N3)2•H2O (s) -308.3608188.28 -105.0184 Ba(NO3)2 (s) -992.06824213.8024 -796.71728 Ba(OH)2•8H2O (s) -3342.1792426.768 -2793.2384 Ba(ReO4)2•4H2O (s) -3368.12376.56 -2918.34 Ba+2 (aq) -537.6449.6232 -560.73968Ba2TiO4 (s) -2243.0424196.648 -2133.0032BaBr2 (s) -757.304146.44 -736.8024BaBr2 (g) -439.32330.536 -472.792BaBr2•2H2O (s) -1366.076225.936 -1230.5144BaCl2 (s) -858.1384123.67904 -810.4408BaCl2 (l) -832.44864143.5112 -790.1484BaCl2 (g) -498.7328325.64072 -510.69904BaCl2•2H2O (s) -1460.13232202.924 -1296.45424witherite) -1216.2888112.1312 -1137.6296 BaCO3 (sBaCrO4 (s) -1445.9904158.5736 -1345.28152BaF2 (s) -1208.757696.39936 -1158.5496-1128.38296 BaF2 (l) -1171.3108121.25232BaF2 (g) -803.7464301.16432 -814.49928-353.42248 BaI2 (g) -302.9216348.1088-587.39176 BaI2 (l) -585.88552183.6776-601.40816 BaI2 (s) -605.4248165.14248 BaMoO4 (s) -1548.08138.072 -1439.7144-520.40592 BaO (s) -548.10472.09032-471.24392 BaO (l) -491.6296.56672-144.80824 BaO (g) -123.8464235.35BaS (s) -460.2478.2408 -456.056BaSeO3 (s) -1040.5608167.36 -968.1776BaSeO4 (s) -1146.416175.728 -1044.7448BaSiF6 (s) -2952.2304163.176 -2794.0752BaSiO3 (s) -1623.6012109.6208 -1540.25592BaSO4 (s) -1473.1864132.2144 -1362.3104BaTiO3 (s) -1659.7928107.9472 -1572.3472BaZrO3 (s) -1779.4552124.6832 -1694.52BBr (g) 238.0696224.89 195.3928-232.46304 BBr3 (g) -205.6436324.13448BBr3 (l) -239.7432229.7016 -238.488BCl (g) 149.49432213.13296 120.9176BCl2F (g) -645.1728284.512 -631.3656-388.73544 BCl3 (g) -403.756289.99304BCl3 (l) -427.1864206.2712 -387.4384BClF2 (g) -890.3552271.96 -876.1296Be (g) 324.26136.1892 286.604Be (l) 12.0499216.5268 9.95792Be (s) 09.53952 0beta) -905.83646.024 -816.7168 Be(OH)2 (sBe+2 (aq) -382.836-129.704 -379.698Be2C (s) -117.15216.3176 -87.864Be2SiO4 (s) -2149.320864.30808 -2032.5872Be3N2 (scubic) -588.270434.14144 -533.0416BeAl2O4 (s) -2300.781666.27456 -2178.6088BeBr2 (s) -369.8656106.2736 -353.1296BeC2 (g) 564.84218.4048 506.264 beta) -496.222475.81408 -449.52896 BeCl2 (salpha) -1026.753653.346 -979.4744 BeF2 (aBeH (g) 326.7704170.87456 298.3192 BeI2 (s) -192.464120.4992 -209.2 alpha) -608.353613.76536 -579.0656 BeO (sBeO (g) 129.704197.52664 104.1816 BeO2-2 (aq) -790.776158.992 -640.152 alpha) -1205.201277.98976 -1093.86496 BeSO4 (sBeSO4•4H2O (s) -2423.74936232.96512 -2080.66136 BeWO4 (s) -1514.60888.36608 -1405.824-149.7872 BF (g) -122.1728200.37176-1120.34968 BF3 (g) -1137.002254.01064BF4-1 (aq) -1574.8576179.912 -1486.9936 BH (g) 449.61264171.7532419.61336 BH4-1 (aq) 48.15784110.4576 114.26504614.50408 BN (g) 647.474212.17064-228.4464 BN (s) -254.387214.81136BO (g) 25.104203.42608 -4.184 BO2 (g) -300.4112229.45056 -305.8504 BO2-1 (aq) -772.3664-37.2376 -678.9376882.428984 Br (g) 111.884344174.91212Br-1 (aq) -121.545282.4248 -103.9724 Br2 (l) 0152.230656 0 Br2 (g) 30.907208245.353944 3.142184 Br2Cl-1 (aq) -170.2888188.6984 -128.4488 Br3-1 (aq) -130.41528215.476 -107.06856 BrCl (g) 14.644239.99424 -0.96232-109.16056 BrF (g) -93.84712228.8648BrF3 (l) -300.8296178.2384 -240.58 BrF3 (g) -255.60056292.41976-229.45056 BrF5 (l) -458.5664225.0992 -351.8744108.24008 BrO (g) 125.77104237.442BrO-1 (aq) -94.1441.84 -33.472 BrO3-1 (aq) -83.68163.176 1.6736671.289328C (g) 716.681544157.98658482.899512diamond) 1.8966072 2.376512C (sgraphite) 0 5.694424 0 C (sC-1 (g) 587.852151.29344 550.6144 C12H22O11 (s) -2225.4696360.2424 -1544.64912781.5712 C2 (g) 837.6368199.28392C2-1 (g) 443.504196.48064 393.296754.3752 C3 (g) 820.064237.2328cyclopropane) 53.30416237.442 104.3908 C3H6 (gC3O2 (l) -117.27752181.08352 -105.0184 C3O2 (g) -93.7216276.3532 -109.83C4H10CH3(CH2)2CH(g n-butane) -126.1476310.11808 -17.1544 3cyclobutane) 26.65208265.39112 110.0392 C4H8 (gC4N2 (g) 533.46289.99304 510.8664cyclopentane) -77.23664292.88 38.61832 C5H10 (gcyclopentane) -105.77152204.26288 36.4008 C5H10 (lcyclohexane) -123.13512298.23552 31.75656 C6H12 (gcyclohexane) -156.23056204.34656 26.65208 C6H12 (ltoluene) 12.00808220.95704 113.76296 C6H5CH3 (ltoluene) 49.9988320.66176 122.00544 C6H5CH3 (gC6H5COOH (s benzoic acid) -385.05352167.5692 -245.26608phenol) -96.35752315.59912 -32.88624 C6H5OH (gphenol) -165.01696144.01328 -50.4172 C6H5OH (sC6H6 (lbenzene) 48.99464173.25944 124.34848benzene) 82.92688269.19856 129.66216 C6H6 (gC7H14 (lcycloheptane) -156.77448242.54648 54.05728cyclooctane) -169.78672262.00208 77.8224 C8H16 (lCa (s) 041.4216 0Ca (l) 10.9202450.66824 8.20064145.51952 Ca (g) 179.2844154.76616Ca(ClO4)2•4H2O (s) -1948.9072433.4624 -1476.82648Ca(H2PO4)2•H2O (s) -3409.66712259.8264 -3058.42032Ca(IO3)2 (s) -1002.4864230.12 -839.3104Ca(IO3)2•6H2O (s) -2780.6864451.872 -2267.728Ca(NO3)2 (s) -938.38752193.3008 -743.20392Ca(NO3)2•2H2O (s) -1540.758269.4496 -1229.34288Ca(NO3)2•3H2O (s) -1838.0312319.2392 -1471.9312Ca(NO3)2•4H2O (s) -2132.33376375.3048 -1713.47352Ca(OH)2 (s) -986.168883.38712 -898.514dolomite) -2326.304155.18456 -2163.5464 Ca[Mg(CO3)2] (sCa+1 (g) 775.2952160.535896 733.4552Ca+2 (aq) -542.83216-53.1368 -553.5432hydroxyapatite) -13476.664780.7344 -12677.52 Ca10(PO4)6(OH)2 (sfluorapatite) -13744.44775.7136 -12982.952 Ca10(PO4)6F2 (sbeta) -3338.832189.24232 -3132.1424 Ca2P2O7 (sbeta) -2307.476127.73752 -2192.8344 Ca2SiO4 (sgamma) -2317.936120.79208 -2201.2024 Ca2SiO4 (sCa3(AsO4)2 (s) -3298.6656225.936 -3063.1064beta) -4120.8216235.9776 -3884.844 Ca3(PO4)2 (sCa3(PO4)2 (salpha) -4109.9432240.91472 -3875.6392CaBr2 (g) -384.928314.6368 -420.95224CaBr2 (s) -683.2472129.704 -664.12632CaBr2 (l) -662.99664147.86256 -649.31496CaBr2•6H2O (s) -2506.216410.032 -2153.0864CaC2 (s) -59.831269.95648 -64.852CaC2O4•H2O (s) -1674.8552156.4816 -1513.9804CaCl2 (s) -795.7968104.6 -748.0992CaCl2 (l) -774.04123.8464 -732.2CaCl2 (g) -471.5368289.9512 -479.068aragonite) -1207.1258488.7008 -1127.7972 CaCO3 (scalcite) -1206.9166492.8848 -1128.8432 CaCO3 (sCaCrO4 (s) -1379.0464133.888 -1277.3752CaF2 (g) -782.408273.6336 -794.96CaF2 (s) -1219.63668.86864 -1167.336CaF2 (l) -1184.07292.59192 -1142.232CaH2 (s) -186.18841.84 -147.2768CaHPO4 (s) -1814.3916111.37808 -1681.25672CaHPO4•2H2O (s) -2403.58248189.45152 -2154.76CaI2 (l) -500.15536178.94968-506.51504-533.12528 CaI2 (s) -536.8072145.26848CaI2 (g) -258.1528327.43984 -308.7792CaMoO4 (s) -1541.3856122.5912 -1434.6936CaO (s) -635.131238.19992 -603.542CaO (l) -557.3506462.29976-532.95792CaO•2Al2O3 (s) -3977.7288177.82 -3770.6208CaO•2B2O3 (s) -3360.25408134.7248 -3167.12064CaO•Al2O3 (s) -2326.304114.2232 -2208.7336CaO•B2O3 (s) -2030.95544104.85104 -1924.09608CaO•Fe2O3 (s) -1520.34008145.35216 -1412.81128diopside) -3206.1992142.92544 -3032.1448 CaO•MgO•2SiO2 (sCaO•V2O5 (s) -2329.27464179.0752 -2169.69688CaS (s) -474.88456.484 -469.8632CaSe (s) -368.19266.944 -363.1712CaSeO4•2H2O (s) -1706.6536221.752 -1486.9936pseudowollastonite)-1628.412887.36192 -1544.7328 CaSiO3 (swollastonite) -1634.9398481.92272 -1549.71176 CaSiO3 (sCaSO3•H2O (s) -1752.6776184.096 -1555.1928CaSO4 (s anhydrite insoluble) -1434.10784106.692 -1321.85112CaSO4 (s alpha soluble) -1425.23776108.3656 -1313.48312CaSO4 (s beta soluble) -1420.80272108.3656 -1309.04808CaSO4•0.5H2O (s beta micro) -1574.6484134.3064 -1435.86512CaSO4•0.5H2O (s alpha macro) -1576.7404130.5408 -1436.82744CaSO4•2H2O (s) -2022.62928194.1376 -1797.4464perovskite) -1660.629693.63792 -1575.276 CaTiO3 (ssphene) -2603.2848129.20192 -2461.8656 CaTiSiO5 (sCaWO4 (s) -1645.1488126.39864 -1538.49864CaZrO3 (s) -1766.9032100.08128 -1681.1312CBr (g) 510.448233.4672 464.424CCl (g) 502.08224.30424 468.60877.44584 Cd (g) 112.00568167.636144gamma) 051.75608 0 Cd (salpha) -0.5857651.75608 -0.58576 Cd (sCd(CN)4-2 (aq) 428.0232322.168 507.5192 Cd(NH3)4+2 (aq) -450.1984336.3936 -226.3544 CdBr2 (s) -316.18488137.2352 -296.31088 CdBr2•4H2O (s) -1492.55832316.3104 -1248.032808 CdCl2 (s) -391.49688115.2692 -343.96664 CdCl2•2.5H2O (s) -1131.93936227.1912 -944.094496 CdCl3-1 (aq) -561.0744202.924 -487.0176 CdCO3 (s) -750.609692.4664 -669.44 CdF2 (s) -700.401677.404 -647.6832-201.37592 CdI2 (s) -202.924161.084CdI4-2 (aq) -341.8328326.352 -315.892 CdO (s) -258.152854.8104 -228.4464 CdS (s) -161.920864.852 -156.4816 CdSb (s) -14.3929692.8848 -13.01224 CdSeO3 (s) -575.3142.256 -497.896 CdSeO4 (s) -633.0392164.4312 -531.7864 CdSiO3 (s) -1189.092897.4872 -1105.4128 CdSO4 (s) -933.28304123.038888 -822.7836 CdSO4•8/3H2O (s) -1729.37272229.630472 -1465.337216 CdSO4•H2O (s) -1239.55184154.029776 -1068.84464 CdTe (s) -92.4664100.416 -92.048 CF (g) 255.224212.92376 221.752 CF+1 (g) 1149.3448201.2504 1115.036 CF2 (g) -182.004240.70552 -191.6272 CF2+1 (g) 941.8184246.6468 924.2456 CH3(CH2)2CH2OH (g 2-butanol) -274.6796362.7528 -150.79136 1-butanol) -327.10512226.3544-162.50656 CH3(CH2)2CH2OH (l-15.0624 n-butane) -147.65336230.9568CH3(CH2)2CH3 (lpentane) -146.44348.9456-8.368 CH3(CH2)3CH3 (ghexane) -167.19264388.40072 -0.25104 CH3(CH2)4CH3 (gCH3(CH2)4CH3 (l hexane) -198.82368296.05984 -3.80744 CH3(CH2)5CH3 (gheptane) -187.77792427.89768 7.99144heptane) -224.38792326.017281.75728 CH3(CH2)5CH3 (l7.40568octane) -249.95216357.732CH3(CH2)6CH3 (l16.40128 CH3(CH2)6CH3 (goctane) -208.44688466.7252nonane) -275.47456393.67256 11.75704 CH3(CH2)7CH3 (lnonane) -229.03216505.67824 24.81112 CH3(CH2)7CH3 (gCH3(CH2)8CH3 (l decane) -301.0388425.5128 -17.53096 1-propanol) -304.00944194.556 -170.62352 CH3CH2CH2OH (l1-propnaol) -256.39552324.72024 -161.79528 CH3CH2CH2OH (gpropane) -103.84688270.20272 -23.55592 CH3CH2CH3 (g2-butanol) -292.62896358.9872 -167.61104 CH3CH2CHOHCH3 (g-177.02504 2-butanol) -342.58592225.0992CH3CH2CHOHCH3 (ldiethyl ether) -273.2152253.132 -116.64992 CH3CH2OCH2CH3 (lCH3CH2OCH2CH3 (gdiethyl ether) -252.12784342.6696 -122.34016ethanol) -276.9808161.04216 -174.17992 CH3CH2OH (lCH3CH2OH (gethanol) -234.42952282.58736 -167.90392ethane) -84.68416229.11584 -32.80256 CH3CH3 (g2-propanol) -272.42024309.90888 -173.38496 CH3CHOHCH3 (g2-propanol) -317.85848180.58144 -180.28856 CH3CHOHCH3 (lacetone) -247.60912200.4136 -155.72848 CH3COCH3 (lacetone) -216.64752294.93016 -153.05072 CH3COCH3 (gCH3COOH (l acetic acid) -484.13064159.8288 -389.9488 CH3COOH (g acetic acid) -434.84312282.50368 -376.68552 CH3OCH3 (g dimethyl ether) -184.05416267.06472 -112.92616 methanol) -201.08304239.70136 -162.42288 CH3OH (gmethanol) -239.03192127.23544 -166.81608 CH3OH (lmethane) -74.85176186.27168 -50.8356 CH4 (g105.31128 Cl (g) 121.29416165.0588-131.25208 Cl-1 (aq) -167.150856.484Cl2 (g) 0222.96536 0 Cl2F6 (g) -339.3224489.528 -237.2328 Cl2O (g) 80.3328267.85968 97.4872 ClF (g) -54.47568217.7772-55.94008 ClF3 (g) -158.992281.49952 -118.8256 ClF3•HF (g) -450.6168359.824 -384.0912 ClF5 (g) -238.488310.62016 -146.44 ClO (g) 101.21096226.5636 97.4872 ClO-1 (aq) -107.110441.84 -36.8192 ClO2 (g) 102.508256.77208 120.33184 ClO2-1 (aq) -66.5256101.2528 17.1544 ClO3-1 (aq) -99.1608162.3392 -3.3472 ClO3F (g) -27.15416278.8636 44.85248 ClO4-1 (aq) -129.32744182.004 -8.61904 CN (g) 435.136202.54744 405.0112 CN+1 (g) 1802.8856213.34216 1763.1376 CN-1 (aq) 150.62494.14 172.3808 CN-1 (g) 60.668195.8112 38.74384 CN2 (g) 581.576231.5844 573.208 CNBr (g) 181.3764247.14888 160.62376 CNCl (g) 132.2144235.47552 125.47816196.14592 CNI (g) 225.0992256.60472169.36832 CNI (s) 160.2472128.8672hexagonal) 030.04112 0 Co (s-137.27704 CO (g) -110.54128197.9032Co (s face centered cubic) 0.4602430.71056 0.25104 Co(IO3)2•2H2O (s) -1081.9824267.776 -795.7968 Co(NH3)6+3 (aq) -584.9232146.44 -157.3184 pink) -539.73679.496 -454.3824 Co(OH)2 (sCo+2 (aq) -58.1576-112.968 -54.392 Co+3 (aq) 92.048-305.432 133.888-394.38384 CO2 (g) -393.5052213.67688CO2 (aq-386.01584 undissoc) -413.7976117.5704CO3-2 (aq) -677.13856-56.9024 -527.89528 Co3O4 (s) -910.02114.2232 -794.96 COBr2 (g) -96.232308.9884 -110.876 CoCl2 (s) -312.5448109.16056 -269.868 COCl2 (g) -220.9152283.75888 -206.77328 CoCl2•2H2O (s) -922.9904188.28 -764.8352 CoCl2•6H2O (s) -2115.4304343.088 -1725.4816 CoCl3 (g) -163.5944334.0924 -154.51512 CoF2 (s) -692.033681.96456 -647.2648 COF2 (g) -640.152258.73856 -624.58752 CoF3 (s) -790.77694.5584 -719.648 CoO (s) -237.9440852.96944 -214.2208-165.64456 COS (g) -138.40672231.45888CoSi (s) -100.41643.0952 -98.7424 CoSO4 (s) -888.2632117.9888 -782.408 CoSO4•6H2O (s) -2683.6176367.60624 -2235.7204 CoSO4•7H2O (s) -2979.92848406.0572 -2473.83184352.58568 Cr (g) 397.48174.2217622.34256 Cr (l) 26.10397636.23344Cr (s) 023.61868 0 Cr23C6 (s) -364.8448610.0272 -373.6312-102.21512 Cr2N (s) -125.5264.852Cr2O3 (s) -1134.700881.1696 -1053.1128 Cr2O3 (l) -1018.3856125.60368 -950.06088 Cr2O7-2 (aq) -1490.3408261.9184 -1301.224 Cr3C2 (s) -85.353685.43728 -86.31592 Cr7C3 (s) -161.9208200.832 -166.9416 CrCl2 (s) -395.388115.31104 -356.0584 CrCl3 (s) -556.472123.0096 -486.1808 CrF3 (s) -1158.96893.88896 -1087.84 CrN (g) 505.0088230.45472471.91336 CrN (s) -117.15237.69784 -92.80112 CrO (g) 188.28239.15744 154.5988 CrO2 (g) -75.312269.11488 -87.36192 CrO2Cl2 (l) -579.484221.752 -510.8664 CrO2Cl2 (g) -538.0624329.6992 -501.6616 CrO3 (g) -292.88266.06056 -273.46624 CrO4-2 (aq) -881.150450.208 -727.84864 Cs (g) 76.5672175.47696 49.78960.025104 Cs (l) 2.08781692.08984Cs (s) 085.1444 0 CS (g) 234.304210.4552 184.096 Cs+1 (aq) 458.5664169.72396 427.1864 CS2 (g) 117.06832237.77672 66.90216 CS2 (l) 89.70496151.33528 65.2704Cs2O (g) -92.048317.984 -104.6CsAl(SO4)2•12H2O (s) -6064.708686.176 -5098.204CsBr (s) -405.68064113.3864 -384.928CsCl (s) -442.83456101.181672 -414.216CsCl (l) -434.2992101.71304 -406.2664CsCl (g) -240.1616255.97712 -257.7344CsF (s) -554.798488.2824 -525.5104-515.09224 CsF (l) -543.8363290.08152CsF (g) -356.4768243.0904 -373.2128CsH (g) 121.336214.43 101.6712-333.71584 CsI (s) -336.812125.52CsOH (s) -416.726498.7424 -362.3344CsOH (g) -259.408255.14032 -259.8264CsOH (l) -406.01536118.44904 -365.8908298.61208 Cu (g) 338.31824166.27216Cu (s) 033.149832 0Cu(C2O4)2-2 (aq) -1592.012146.44 -1335.9512Cu(IO3)2•H2O (s) -692.0336247.2744 -468.608Cu(NH3)+2 (aq) -38.911212.1336 15.56448Cu(NH3)2+2 (aq) -142.256111.2944 -30.45952Cu(NH3)3+2 (aq) -245.6008199.5768 -73.13632Cu(NH3)4+2 (aq) -348.5272273.6336 -111.2944Cu(OH)2 (s) -450.1984108.3656 -372.7944Cu+1 (aq) 71.6719240.5848 49.9988Cu+2 (aq) 64.76832-99.5792 65.52144431.95616 Cu2 (g) 484.17248241.45864Cu2O (s) -168.615293.13584 -146.0216alpha) -79.496120.9176 -86.1904 Cu2S (sCuBr (s) -104.696.10648 -100.8344CuCl (s) -137.235286.1904 -119.8716CuCl2 (s) -205.8528108.07272 -161.9208CuCl2•2H2O (s) -821.3192167.36 -656.0512CuCN (s) 94.976889.99784 108.3656malachite) -1051.4392186.188 -893.7024 CuCO3•Cu(OH)2 (sCuF (s) -192.46464.852 -171.544CuF2 (s) -548.940868.6176 -499.1512CuFe2O4 (s) -965.20696141.0008 -858.80784CuFeO2 (s) -532.623288.7008 -479.9048CuI (s) -67.780896.6504 -69.4544CuN3 (s) 279.0728100.416 344.7616CuO (s) -157.318442.63496 -129.704CuS (s) -53.136866.5256 -53.5552CuSO4 (s) -771.36224108.784 -661.9088CuSO4•3H2O (s) -1684.31104221.3336 -1400.1756CuSO4•5H2O (s) -2279.6524300.4112 -1880.055296CuSO4•H2O (s) -1085.83168146.0216 -918.22064F (g) 78.99392158.6572861.9232-262.3368 F-1 (g) -255.6424145.47768F2 (g) 0202.7148 0alpha) 027.27968 0 Fe (s11.049944 Fe (l) 13.12939234.28788Fe(CN)6-3 (aq) 561.9112270.2864 729.2712Fe(CN)6-4 (aq) 455.637694.9768 694.92056Fe(CO)5 (l) -774.04338.0672 -705.4224Fe(CO)5 (g) -733.8736445.1776 -697.2636Fe(OH)+2 (aq) -290.788-142.256 -229.40872Fe+2 (aq) -89.1192-137.6536 -78.8684Fe+3 (aq) -48.5344-315.892 -4.6024Fe2(SO4)3 (s) -2581.528307.524 -2263.1256hematite) -824.24887.40376 -742.2416 Fe2O3 (sfayalite) -1479.8808145.1848 -1379.0464 Fe2SiO4 (salpha-cementite) 25.104104.6 20.0832 Fe3C (smagnetite) -1118.3832146.44 -1015.4568 Fe3O4 (sFe3Si (s) -93.7216103.7632 -94.5584Fe4N (s) -10.46156.0632 3.7656pyrrhotite) -736.384485.7624 -748.5176 Fe7S8 (sFeAl2O4 (s) -1966.48106.2736 -1849.328FeAsS (s) -41.84121.336 -50.208FeBr2 (s) -249.7848140.66608 -237.2328FeCl2 (s) -341.79096117.94696 -302.33584FeCl3 (s) -399.48832142.256 -334.05056siderite) -740.56892.8848 -666.7204 FeCO3 (sFeCr2O4 (s) -1444.7352146.0216 -1343.9008FeF2 (s) -702.91286.98536 -661.072FeF3 (s) -1041.81698.324 -970.688FeI2 (s) -104.6167.36 -112.968FeMoO4 (s) -1075.288129.2856 -974.872FeO (s) -271.9660.75168 -251.4584FeOH+1 (aq) -324.6784-29.288 -277.3992strengite) -1888.2392171.25112 -1657.7008 FePO4•2H2O (spyrrhotite) -99.997660.29144 -100.416 FeS (spyrite) -178.238452.9276 -166.9416 FeS2 (sFeSi (s) -73.638446.024 -73.6384beta-lebanite) -81.169655.6472 -78.2408 FeSi2 (sFeSO4 (s) -928.4296120.9176 -825.0848FeSO4•7H2O (s) -3014.572409.1952 -2510.27448FeWO4 (s) -1154.784131.796 -1054.368FNO3 (g) 10.46292.88 73.6384Fr (s) 094.14 0Fr (g) 72.8016181.92032 46.6516Fr2O (s) -338.904156.9 -299.156H+1 (aq) 00 0H2 (g) 0130.586824 0 H2AsO4-1 (aq) -909.55976117.152 -753.28736 H2CS3 (l) 25.104223.0072 27.8236 H2MoO4 (g) -851.0256355.64 -787.4288-228.588656 H2O (g) -241.818464188.715136-237.178408 H2O (l) -285.8299669.91464H2O2 (g) -136.10552232.88144 -105.47864 H2O2 (l) -187.77792109.6208 -120.41552 H2PO4-1 (aq) -1296.2868890.3744 -1130.39128 H2S (g) -20.16688205.76912 -33.0536 H2Se (g) 29.7064218.90688 15.8992 H2Se (g) 29.7064218.90688 15.8992 H2SiO3 (s) -1188.6744133.888 -1092.4424 H2SO4 (l) -813.9972156.9 -690.06712 H2SO4 (g) -740.568289.1144 -656.0512 H2VO4-1 (aq) -1174.0304121.336 -1020.896 H2WO4 (s) -1131.772146.44 -1004.16 H2WO4 (g) -905.4176351.456 -839.7288 H3BO3 (s) -1094.325288.82632 -969.0144 H3PO4 (l) -1254.3632150.624 -1111.6888 H3PO4 (s) -1266.9152110.54128 -1112.5256 H4SiO4 (s) -1481.136192.464 -1333.0224 HAsO4-2 (aq) -906.33808-1.6736 -714.71088 orthorhombic) -788.7676850.208 -721.74 HBO2 (smonoclinic) -794.2487237.656 -723.4136 HBO2 (s-53.51336 HBr (g) -36.44264198.61448-95.31152 HCl (g) -92.29904186.77376HClO (g) -92.048236.6052 -79.496 HCN (g) 135.1432201.6688 124.6832 HCN (l) 108.86768112.84248 124.93424 HCO3-1 (aq) -691.9917691.2112 -586.84784 HCrO4-1 (aq) -878.2216184.096 -764.8352 He (g) 0126.038816 0-273.2152 HF (g) -271.1232173.67784Hg (l) 076.02328 031.852792 Hg (g) 61.31652174.84936Hg(CH3)2 (l) 59.8312209.2 140.164 Hg(CH3)2 (g) 94.39104305.432 146.0216 Hg2(N3)2 (s) 594.128205.016 746.4256 Hg2Br2 (s) -206.8988218.73952 -181.075152 Hg2Cl2 (s) -265.22376192.464 -210.777368 Hg2CO3 (s) -553.5432179.912 -468.1896 Hg2F2 (s) -485.344158.992 -426.768 Hg2I2 (s) -121.336242.672 -111.00152 Hg2SO4 (s) -743.12024200.66464 -625.880376 HgBr2 (s) -170.7072170.33064 -153.1344HgCl (g) 84.0984259.78456 62.76 HgCl2 (s) -224.2624146.0216 -178.6568 HgF2 (s) -422.584116.3152 -372.376 HgH (g) 239.99424219.49264216.01992 HgI (g) 132.38176281.41584 88.44976 HgI2 (g) -17.1544336.01704 -59.8312 HgI2 (sred) -105.4368181.1672 -101.6712-58.425376 HgO (syellow) -90.4580871.128HgO (s red hexagonal) -89.537671.128 -58.24128 HgO (s red orthorhombic) -90.8346470.2912 -58.55508 HgS (sred) -58.157682.4248 -50.6264black) -53.555288.2824 -47.6976 HgS (sHgSe (g) 75.7304267.02288 31.38 HgSe (s) -46.02494.14 -38.0744 HgTe (s) -33.8904106.692 -28.0328 HI (g) 26.48472206.4804 1.71544 HN2O2-1 (aq) -39.3296142.256 76.1488 HN3 (g) 294.1352238.86456 328.0256 HNCO (g) -116.7336238.11144 -107.36144 HNCS (g) 127.612247.6928 112.968 cis) -76.5672249.32456 -41.84 HNO2 (gtrans) -78.6592249.1572 -43.932 HNO2 (gHNO3 (l) -173.2176155.60296 -79.9144 HNO3 (g) -135.05952266.26976 -74.76808 HOF (g) -98.324226.64728 -85.64648 HPO4-2 (aq) -1292.14472-33.472 -1089.26256 HReO4 (s) -762.3248158.1552 -664.8376 HS-1 (aq) -17.572862.76 12.04992 HSe-1 (aq) 15.899279.496 43.932 HSeO3-1 (aq) -514.54832135.1432 -411.53824 HSeO3-1 (aq) -514.54832135.1432 -411.53824 HSeO4-1 (aq) -581.576149.3688 -452.2904 HSeO4-1 (aq) -581.576149.3688 -452.2904 HSO3-1 (aq) -626.21928139.7456 -527.8116 HSO3F (g) -753.12297.064 -690.36 HVO4-2 (aq) -1158.96816.736 -974.87270.282832I (g) 106.83844180.681856-51.58872 I-1 (aq) -55.18696111.2944I2 (s) 0116.135288 0 I2 (g) 62.437832260.5795219.359368 IBr (g) 40.83584258.663248 3.72376 ICl (l) -23.89064135.1432 -13.598 ICl (g) 17.782247.44176 -5.4392-22.34256 ICl3 (s) -89.5376167.36-118.49088 IF (g) -95.64624236.06128-771.5296 IF5 (g) -840.1472334.72IF7 (g) -943.9104346.4352-818.3904149.7872 IO (g) 175.05856245.3916IO-1 (aq) -107.5288-5.4392 -38.4928 IO3-1 (aq) -221.3336118.4072 -128.0304 K (g) 89.119290.03968 60.668 K (l) 2.28446471.462720.263592 K (s) 064.68464 0 K2B4O7 (s) -3334.2296208.3632 -3136.7448 K2CO3 (s) -1150.1816155.51928 -1064.4096 K2O (s) -363.171294.14 -322.168 K2O2 (s) -495.804112.968 -429.6968 K2SiO3 (s) -1548.08146.14712 -1455.6136 K2SO4 (s) -1433.68944175.728 -1316.37008 K3AlCl6 (s) -2092376.56 -1938.4472 KAl(SO4)2 (s) -2465.38016204.5976 -2235.46936 KAl(SO4)2•12H2O (s) -6057.34416687.4312 -5137.1152 KAlCl4 (s) -1196.624196.648 -1096.208 KBF4 (s) -1886.984133.888 -1784.8944 KBH4 (s) -226.7728106.60832 -159.8288 KBO2 (s) -994.955279.99808 -978.6376-379.19592 KBr (s) -392.1663296.4412KBrO3 (s) -332.2096149.1596 -243.5088 KCl (s) -435.8891282.67584-408.31656-235.1408 KCl (g) -215.8944239.49216KClO3 (s) -391.204142.96728 -289.90936 KClO4 (s) -430.1152151.0424 -300.4112-102.04776 KCN (s) -113.47008127.77936-538.8992 KF (s) -568.605666.56744 KF•2H2O (s) -1158.968150.624 -1015.4568-34.05776 KH (s) -57.8228850.208KH2AsO4 (s) -1135.956155.14272 -991.608 KHF2 (s) -931.3584104.26528 -863.1592-322.29352 KI (s) -327.64904106.39912KIO3 (s) -508.356151.4608 -425.5128 KMnO4 (s) -813.3696171.71136 -713.7904 KNO3 (s) -492.70784132.92568 -393.12864 KO2 (s) -284.512122.5912 -240.58 KOH (s) -425.8475278.8684 -379.0704 Kr (g) 0163.975144 0128.0304 Li (g) 160.6656138.657760.933032 Li (l) 2.38069633.93224Li (s) 0160.6656 0 Li2B4O7 (s) -3363.936155.6448 -3171.472 Li2BeF4 (s) -2273.5856130.5408 -2171.496 Li2CO3 (s) -1216.0377690.1652 -1132.1904 Li2O (s) -598.730437.90704 -561.9112。

化工进展Chemical Industry and Engineering Progress2024 年第 43 卷第 3 期四种烷基咪唑磷酸酯离子液体的热力学性质刘泽鹏，曾纪珺，唐晓博，赵波，韩升，廖袁淏，张伟（西安近代化学研究所氟氮化工资源高效开发与利用国家重点实验室，陕西 西安 710065）摘要：针对烷基咪唑磷酸酯离子液体的热物性数据较少的问题，本文在常压下测定了1-乙基-3-甲基咪唑磷酸二氢盐（[EMIM][DHP]）、1-乙基-3-甲基咪唑磷酸二甲酯盐（[EMIM][DMP]）、1-乙基-3-甲基咪唑磷酸二乙酯盐（[EMIM][DEP]）、1-丁基-3-甲基咪唑磷酸二丁酯盐（[BMIM][DBP]）四种烷基咪唑磷酸酯离子液体的密度、黏度（293.15~353.15K ）和电导率（293.15~343.15K ），并且测定了四种离子液体的热稳定性。

结果表明，离子液体的密度、黏度随温度的升高而减小，而电导率随温度的升高而增大。

采用自然对数方程关联四种离子液体的密度，根据实验值计算到了离子液体体积性质；采用VFT 方程关联离子液体黏度和电导率，其中密度与电导率的实验值与模型相关系数R 2达到0.9999，黏度相关系数R 2达到0.99999，实验测定的数据与模型一致；四种离子液体的热稳定性相近，分解温度均在271.9~278.6℃范围内；瓦尔登规则分析表明，四种烷基咪唑磷酸酯离子液体符合Walden 规则，而[EMIM][DMP]和[EMIM][DEP]被归类为“good ionic liquids ”。

关键词：烷基咪唑磷酸酯离子液体；密度；黏度；电导率；热稳定性中图分类号：TQ013.1 文献标志码：A 文章编号：1000-6613（2024）03-1484-08Thermodynamic properties of four alkyl imidazolium phosphate ionicliquidsLIU Zepeng ，ZENG Jijun ，TANG Xiaobo ，ZHAO Bo ，HAN Sheng ，LIAO Yuanhao ，ZHANG Wei(State Key Laboratory of Fluorine & Nitrogen Chemicals, Xi ’an Modern Chemistry Research Institute, Xi ’an 710065,Shaanxi, China)Abstract: The density, viscosity, and conductivity of 1-ethyl-3-methylimidazolium dihydrogen-phosphate ([EMIM][DHP]), 1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM][DMP]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]) and 1-butyl-3-methylimidazolium dibutyl-phosphate ([BMIM][DBP]) ionic liquids were measured in the temperature range of 293.15K to 353.15K under ambient conditions. Some important volumetric properties, including the isobaric thermal expansion coefficients, molecular volume, standard entropy and lattice potential energy were calculated from the experimental density values. The thermal gravimetric analysis was performed in the temperature range of 35℃ to 700℃, resulting in thermal decomposition temperatures up to 271.9—278.6℃. The Walden rule analysis demonstrated that four phosphate ionic liquids complied with the Walden rule well, while [EMIM][DMP] and [EMIM][DEP] were classified as “good ionic liquids ”.Keywords: alkyl imidazolium phosphate ionic liquids; density; viscosity; conductivity; thermal stability研究开发DOI ：10.16085/j.issn.1000-6613.2023-1722收稿日期：2023-09-28；修改稿日期：2023-12-05。

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第 29 卷第 1 期分析测试技术与仪器Volume 29 Number 1 2023年3月ANALYSIS AND TESTING TECHNOLOGY AND INSTRUMENTS Mar. 2023大型仪器功能开发(30 ~ 36)正负压一体式无空气X射线光电子能谱原位转移仓的开发及研制章小余，赵志娟，袁　震，刘　芬（中国科学院化学研究所，北京　100190）摘要：针对空气敏感材料的表面分析，为了获得更加真实的表面组成与结构信息，需要提供一个可以保护样品从制备完成到分析表征过程中不接触大气环境的装置. 通过使用O圈密封和单向密封柱，提出一种简便且有效的设计概念，自主研制了正负压一体式无空气X射线光电子能谱（XPS）原位转移仓，用于空气敏感材料的XPS测试，利用单向密封柱实现不同工作需求下正负压两种模式的任意切换. 通过对空气敏感的金属Li片和CuCl粉末进行XPS分析表明，采用XPS原位转移仓正压和负压模式均可有效避免样品表面接触空气，保证测试结果准确可靠，而且采用正压密封方式转移样品可以提供更长的密封时效性. 研制的原位转移仓具有设计小巧、操作简便、成本低、密封效果好的特点，适合给有需求的用户开放使用.关键词：空气敏感；X射线光电子能谱；原位转移；正负压一体式中图分类号：O657; O641; TH842 文献标志码：B 文章编号：1006-3757（2023）01-0030-07 DOI：10.16495/j.1006-3757.2023.01.005Development and Research of Inert-Gas/Vacuum Sealing Air-Free In-Situ Transfer Module of X-Ray Photoelectron SpectroscopyZHANG Xiaoyu， ZHAO Zhijuan， YUAN Zhen， LIU Fen（Institute of Chemistry Chinese Academy of Sciences, Beijing 100190, China）Abstract：For the surface analysis of air sensitive materials, and from the sample preparation to characterization, it is necessary to provide a device that can protect samples from exposing to the atmosphere environment so as to obtain accurate and impactful data of the surface chemistry. Through the use of O-ring and one-way sealing, a simple and effective design concept has been demonstrated, and an inert-gas/vacuum sealing air-free X-ray photoelectron spectroscopic (XPS) in-situ transfer module has been developed to realize the XPS analysis of air sensitive materials. The design of one-way sealing was achieved conveniently by switching between inert-gas and vacuum sealing modes in face of different working requirements. The XPS analysis of air-sensitive metal Li sheets and CuCl powders showed that both the sealing modes (an inert-gas/vacuum sealing) of the XPS in-situ transfer module can effectively avoid air contact on the sample surface, and consequently, can ensure the accuracy and reliability of XPS data. Furthmore, the inert gas sealing mode can keep the sample air-free for a longer time. The homemade XPS in-situ transfer module in this work is characterized by a compact design, convenient operation, low cost and effective sealing, which is suitable for the open access to the users who need it.收稿日期：2022−12−07；　修订日期：2023−01−17.基金项目：中国科学院化学研究所仪器孵化项目[Instrument and Device Functional Developing Project of Institute of Chemistry Chinese Academy of Sciences]作者简介：章小余（1986−），女，硕士，工程师，主要研究方向为电子能谱技术及材料表面分析，E-mail：xyiuzhang@ .Key words：air-sensitive；X-ray photoelectron spectroscopy；in-situ transfer；inert-gas/vacuum sealingX射线光电子能谱（XPS）是一种表面灵敏的分析技术，通常用于固体材料表面元素组成和化学态分析[1]. 作为表面分析领域中最有效的方法之一，XPS广泛应用于纳米科学、微电子学、吸附与催化、环境科学、半导体、冶金和材料科学、能源电池及生物医学等诸多领域[2-3]. 其中在催化和能源电池材料分析中，有一些样品比较特殊，比如碱金属电池[4-6]、负载型纳米金属催化剂[7-8]和钙钛矿材料[9]对空气非常敏感，其表面形态和化学组成接触空气后会迅速发生改变，直接影响采集数据的准确性和有效性，因此这类样品的表面分析测试具有一定难度. 目前，常规的光电子能谱仪制样转移过程通常是在大气环境中，将样品固定在标准样品台上，随后放入仪器进样室内抽真空至1×10−6 Pa，再转入分析室内进行测试. 这种制备和进样方式无法避免样品接触大气环境，对于空气敏感材料，其表面很容易与水、氧发生化学反应，导致无法获得材料表面真实的结构信息.为了保证样品表面状态在转移至能谱仪内的过程中不受大气环境影响，研究人员采用了各种技术来保持样品转移过程中隔绝空气. 比如前处理及反应装置与电子能谱仪腔室间真空传输[10-12]、外接手套箱 [13-14]、商用转移仓[15-16]、真空蒸镀惰性金属比如Al层（1.5~6 nm）[17]等. 尽管上述技术手段有效，但也存在一些缺点，例如配套装置体积巨大、试验过程不易操作、投入成本高等，这都不利于在普通实验室内广泛应用. 而一些电子能谱仪器制造商根据自身仪器的特点也研发出了相应配套的商用真空传递仓，例如Thermofisher公司研发的一种XPS 真空转移仓，转移过程中样品处于微正压密封状态，但其价格昂贵，体积较大，转移过程必须通过手套箱大过渡舱辅助，导致传递效率低，单次需消耗至少10 L高纯氩气，因此购置使用者较少，利用率低.另外有一些国内公司也研发了类似的商品化气体保护原位传递仓，采用微正压方式密封转移样品，但需要在能谱仪器进样室舱门的法兰上外接磁耦合机械旋转推拉杆，其操作复杂且放置样品的有效区域小，单次仅可放置尺寸为3 mm×3 mm的样品3～4个，进样和测试效率较低. 因此，从2016年起本实验团队开始自主研制XPS原位样品转移装置[18]，经过结构与性能的迭代优化[19]，最终研制出一种正负压一体式无空气XPS原位转移仓[20]（本文简称XPS原位转移仓），具有结构小巧、操作便捷、成本低、密封效果好、正压和负压密封两种模式转移样品的特点. 为验证装置的密封时效性能，本工作选取两种典型的空气敏感材料进行测试，一种是金属Li材料，其化学性质非常活泼，遇空气后表面迅速与空气中的O2、N2、S等反应导致表面化学状态改变. 另一种是无水CuCl粉末，其在空气中放置短时间内易发生水解和氧化. 试验结果表明，该XPS 原位转移仓对不同类型的空气敏感样品的无空气转移均可以提供更便捷有效的密封保护. 目前，XPS原位转移仓已在多个科研单位的实验室推广使用，支撑应用涉及吸附与催化、能源环境等研究领域.1　试验部分1.1　XPS原位转移仓的研制基于本实验室ESCALAB 250Xi型多功能光电子能谱仪器（Thermofisher 公司）的特点，研究人员设计了XPS原位转移仓. 为兼顾各个部件强度、精度与轻量化的要求，所有部件均采用钛合金材料.该装置从整体结构上分为样品台、密封罩和紧固挡板三个部件，如图1（a）~（c）所示. 在密封罩内部通过单向密封设计[图1（e）]使得XPS原位转移仓实现正负压一体，实际操作中可通过调节密封罩上的螺帽完成两种模式任意切换. 同时，从图1（e）中可以直观看到，密封罩与样品台之间通过O圈密封，利用带有螺钉的紧固挡板将二者紧密固定. 此外，为确保样品台与密封罩对接方位正确，本设计使用定向槽定位样品台与密封罩位置，保证XPS原位转移仓顺利传接到仪器进样室.XPS原位转移仓使用的具体流程：在手套箱中将空气敏感样品粘贴至样品台上，利用紧固挡板使样品台和密封罩固定在一起，通过调节密封罩上的螺帽将样品所在区域密封为正压惰性气氛（压强为300 Pa、环境气氛与手套箱内相同）或者负压真空状态，其整体装配实物图如图1（d）所示. 该转移仓结构小巧，整体尺寸仅52 mm×58 mm×60 mm，可直接放入手套箱小过渡舱传递. 由于转移仓尺寸小，其第 1 期章小余，等：正负压一体式无空气X射线光电子能谱原位转移仓的开发及研制31原料成本大大缩减，整体造价不高. 转移仓送至能谱仪进样室后，配合样品停放台与进样杆的同时双向对接，将转移仓整体固定在进样室内，如图1（f ）所示. 此时关闭进样室舱门开始抽真空，当样品台与密封罩内外压强平衡后密封罩自动解除真空密封，但仍然处于O 圈密闭状态. 等待进样室真空抽至1×10−4Pa 后，使用能谱仪进样室的样品停放台摘除脱离的密封罩[如图1（g ）所示]，待真空抽至1×10−6Pa ，即可将样品送入分析室进行XPS 测试.整个试验过程操作便捷，实现了样品从手套箱转移至能谱仪内不接触大气环境.1.2　试验过程1.2.1　样品准备及转移试验所用手套箱是布劳恩惰性气体系统（上海）有限公司生产，型号为MB200MOD （1500/780）NAC ；金属Li 片购自中能锂业，纯度99.9%；CuCl 购自ALFA 公司，纯度99.999%.金属Li 片的制备及转移：将XPS 原位转移仓整体通过手套箱过渡舱送入手套箱中，剪取金属Li 片用双面胶带固定于样品台上，分别采用正压、负压两种密封模式将XPS 原位转移仓整体从手套箱中取出，分别在空气中放置0、2、4、8、18、24、48、72 h 后送入能谱仪内，进行XPS 测试.CuCl 粉末的制备及转移：在手套箱中将CuCl 粉末压片[21]，使用上述同样的制备方法，将XPS 原位转移仓整体在空气中分别放置0、7、24、72 h 后送入能谱仪内，进行XPS 测试.1.2.2　样品转移方式介绍样品在手套箱中粘贴完成后，分别采用三种方式将其送入能谱仪. 第一种方式是在手套箱内使用标准样品台粘贴样品，将其装入自封袋密封，待能谱仪进样室舱门打开后，即刻打开封口袋送入仪器中开始抽真空等待测试，整个转移过程中样品暴露空气约15 s. 第二种方式是使用XPS 原位转移仓负压密封模式转移样品，具体操作步骤：利用紧固挡板将样品台和密封罩固定在一起，逆时针（OPEN ）旋动螺帽至顶部，放入手套箱过渡舱并将其抽为真空，此过程中样品所在区域也抽至负压. 取出整体装置后再顺时针（CLOSE ）旋动螺帽至底部，将样品所在区域进一步锁死密封. 样品在负压环境中转移至XPS 实验室，拆卸掉紧固挡板，随即送入能谱仪进样室内. 第三种方式是使用XPS 原位转移仓正压密封模式转移样品，具体操作步骤：利用紧固挡板将样品台和密封罩固定在一起，顺时针（CLOSE ）旋螺帽抽气管限位板单向密封柱密封罩主体O 圈样品台紧固挡板(e) 密封罩对接停放台机械手样品台对接进样杆(a)(b)(c)(d)(g)图1　正负压一体式无空气XPS 原位转移仓系统装置（a ）样品台，（b ）密封罩，（c ）紧固挡板，（d ）整体装配实物图，（e ）整体装置分解示意图，（f ）样品台与密封罩在进样室内对接完成，（g ）样品台与密封罩在进样室内分离Fig. 1　System device of inert-gas/vacuum sealing air-free XPS in-situ transfer module32分析测试技术与仪器第 29 卷动螺帽至底部，此时样品所在区域密封为正压惰性气氛. 直至样品转移至XPS 实验室，再使用配套真空抽气系统（如图2所示），通过抽气管将样品所在区域迅速抽为负压，拆卸掉紧固挡板，随即送入能谱仪进样室内.图2　能谱仪实验室内配套真空抽气系统Fig. 2　Vacuum pumping system in XPSlaboratory1.2.3　XPS 分析测试试验所用仪器为Thermo Fisher Scientific 公司的ESCALAB 250Xi 型多功能X 射线光电子能谱仪，仪器分析室基础真空为1×10−7Pa ，X 射线激发源为单色化Al 靶（Alk α，1 486.6 eV ），功率150 W ，高分辨谱图在30 eV 的通能及0.05 eV 的步长等测试条件下获得，并以烃类碳C 1s 为284.8 eV 的结合能为能量标准进行荷电校正.2　结果与讨论2.1　测试结果分析为了验证XPS 原位转移仓的密封性能，本文做了一系列的对照试验，选取空气敏感的金属Li 片和CuCl 粉末样品进行XPS 测试，分别采用上述三种方式转移样品，并考察了XPS 原位转移仓密封状态下在空气中放置不同时间后对样品测试结果的影响.2.1.1　负压密封模式下XPS 原位转移仓对金属Li片的密封时效性验证将金属Li 片通过两种（标准和负压密封）方式转移并在空气中放置不同时间，对这一系列样品进行XPS 测试，Li 1s 和C 1s 高分辨谱图结果如图3（a ）（b ）所示，试验所测得的Li 1s 半峰宽值如表1所列. 根据XPS 结果分析，金属Li 片采用标准样品台进样（封口袋密封），短暂暴露空气约15 s ，此时Li 1s 的半峰宽为1.62 eV. 而采用XPS 原位转移仓负压密封模式转移样品时，装置整体放置空气18 h 内，Li 1s 的半峰宽基本保持为（1.35±0.03） eV. 放置空气24 h 后，Li 1s 的半峰宽增加到与暴露空气15 s 的金属Li 片一样，说明此时原位转移仓的密封性能衰减，金属Li 片与渗入内部的空气发生反应生成新物质导致Li 1s 半峰宽变宽. 由图3（b ）中C 1s 高分辨谱图分析，结合能位于284.82 eV 的峰归属为C-C/污染C ，位于286.23 eV 的峰归属为C-OH/C-O-CBinding energy/eVI n t e n s i t y /a .u .Li 1s半峰宽增大暴露 15 s密封放置 24 h 密封放置 18 h 密封放置 8 h 密封放置 4 h 密封放置 0 h6058565452Binding energy/eVI n t e n s i t y /a .u .C 1s(a)(b)暴露 1 min 暴露 15 s 密封放置 24 h 密封放置 18 h 密封放置 0 h292290288284282286280图3　金属Li 片通过两种（标准和负压密封）方式转移并在空气中放置不同时间的（a ）Li 1s 和（b ）C 1s 高分辨谱图Fig. 3　High-resolution spectra of (a) Li 1s and (b) C 1s of Li sheet samples transferred by two methods (standard andvacuum sealings) and placed in air for different times第 1 期章小余，等：正负压一体式无空气X 射线光电子能谱原位转移仓的开发及研制33键，位于288.61~289.72 eV的峰归属为HCO3−/CO32−中的C[22]. 我们从C 1s的XPS谱图可以直观的看到，与空气短暂接触后，样品表面瞬间生成新的结构，随着暴露时间增加到1 min，副反应产物大量增加（HCO3−/CO32−）. 而XPS原位转移仓负压密封模式下在空气中放置18 h内，C结构基本不变，在空气中放置24 h后，C结构只有微小变化. 因此根据试验结果分析，对于空气极其敏感的材料，在负压密封模式下，建议XPS原位转移仓在空气中放置时间不要超过18 h. 这种模式适合对空气极其敏感样品的短距离转移.表 1 通过两种（标准和负压密封）方式转移并在空气中放置不同时间的Li 1s的半峰宽Table 1　Full width at half maxima (FWHM) of Li 1stransferred by two methods (standard and vacuum sealings) and placed in air for different times样品说明进样方式半峰宽/eV密封放置0 h XPS原位转移仓负压密封模式转移1.38密封放置2 h同上 1.39密封放置4 h同上 1.36密封放置8 h同上 1.32密封放置18 h同上 1.32密封放置24 h同上 1.62暴露15 s标准样品台进样（封口袋密封）1.622.1.2　正压密封模式下原位转移仓对金属Li片的密封时效性验证将金属Li片通过两种（标准和正压密封）方式转移并在空气中放置不同时间，对这一系列样品进行XPS测试，Li 1s高分辨谱图结果如图4所示，所测得的Li 1s半峰宽值如表2所列. 根据XPS结果分析，XPS原位转移仓正压密封后，在空气中放置72 h内，Li 1s半峰宽基本保持为（1.38±0.04） eV，说明有明显的密封效果，金属Li片仍然保持原有化学状态. 所以对于空气极其敏感的材料，在正压密封模式下，可至少在72 h内保持样品表面不发生化学态变化. 这种模式适合长时间远距离（可全国范围内）转移空气敏感样品.2.1.3　负压密封模式下XPS原位转移仓对空气敏感样品CuCl的密封时效性验证除了金属Li片样品，本文还继续考察XPS原位转移仓对空气敏感样品CuCl的密封时效性. 图5为CuCl粉末通过两种（标准和负压密封）方式转移并在空气中放置不同时间的Cu 2p高分辨谱图. XPS谱图中结合能[22]位于932.32 eV的峰归属为Cu+的Cu 2p3/2，位于935.25 eV的峰归属为Cu2+的Cu 2p3/2，此外，XPS谱图中位于940.00~947.50 eV 处的峰为Cu2+的震激伴峰，这些震激伴峰被认为是表 2 通过两种（标准和正压密封）方式转移并在空气中放置不同时间的Li 1s的半峰宽Table 2　FWHM of Li 1s transferred by two methods(standard and inert gas sealings) and placed in air fordifferent times样品说明进样方式半峰宽/eV 密封放置0 h XPS原位转移仓正压密封模式转移1.42密封放置2 h同上 1.35密封放置4 h同上 1.35密封放置8 h同上 1.34密封放置18 h同上 1.38密封放置24 h同上 1.39密封放置48 h同上 1.42密封放置72 h同上 1.38暴露15 s标准样品台进样（封口袋密封）1.62Binding energy/eVIntensity/a.u.Li 1s半峰宽比正压密封的宽半峰宽=1.62 eV半峰宽=1.38 eV暴露 15 s密封放置 72 h密封放置 48 h密封放置 24 h密封放置 18 h密封放置 0 h605856545250图4　金属Li片通过两种（标准和正压密封）方式转移并在空气中放置不同时间的Li 1s高分辨谱图Fig. 4　High-resolution spectra of Li 1s on Li sheet samples transferred by two methods (standard and inert gas sealings) and placed in air for different times34分析测试技术与仪器第 29 卷价壳层电子向激发态跃迁的终态效应所产生[23]，而在Cu +和Cu 0中则观察不到.根据XPS 结果分析，CuCl 在XPS 原位转移仓保护（负压密封）下，即使放置空气中72 h ，测得的Cu 2p 高分辨能谱图显示只有Cu +存在，说明CuCl 并未被氧化. 若无XPS 原位转移仓保护，CuCl 粉末放置空气中3 min 就发生了比较明显的氧化，从测得的Cu 2p 高分辨能谱图能够直观的看到Cu 2+及其震激伴峰的存在，并且随着放置时间增加到40 min ，其氧化程度也大大增加. 因此，对于空气敏感的无机材料、纳米催化剂和钙钛矿材料等，采用负压密封模式转移就可至少在72 h 内保持样品表面不发生化学态变化.3　结论本工作中自主研制的正负压一体式无空气XPS原位转移仓在空气敏感样品转移过程中可以有效隔绝空气，从而获得样品最真实的表面化学结构.试验者可根据样品情况和实验室条件选择转移模式，并在密封有效时间内将样品从实验室转移至能谱仪中完成测试. 综上所述，该XPS 原位转移仓是一种设计小巧、操作简便、密封性能优异、成本较低的样品无水无氧转移装置，因此非常适合广泛开放给有需求的试验者使用. 在原位和准原位表征技术被广泛用于助力新材料发展的现阶段，希望该设计理念能对仪器功能的开发和更多准原位表征测试的扩展提供一些启示.参考文献：黄惠忠. 论表面分析及其在材料研究中的应用[M ].北京: 科学技术文献出版社, 2002: 16-18.［ 1 ］杨文超, 刘殿方, 高欣, 等. 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第 12 卷第 12 期2023 年 12 月Vol.12 No.12Dec. 2023储能科学与技术Energy Storage Science and Technology耦合光热发电储热-有机朗肯循环的先进绝热压缩空气储能系统热力学分析尹航1，王强1，朱佳华2，廖志荣2，张子楠1，徐二树2，徐超2（1中国广核新能源控股有限公司，北京100160；2华北电力大学能源动力与机械工程学院，北京102206）摘要：先进绝热压缩空气储能是一种储能规模大、对环境无污染的储能方式。

为了提高储能系统效率，本工作提出了一种耦合光热发电储热-有机朗肯循环的先进绝热压缩空气储能系统(AA-CAES+CSP+ORC)。

该系统中光热发电储热用来解决先进绝热压缩空气储能系统压缩热有限的问题，而有机朗肯循环发电系统中的中低温余热发电来进一步提升储能效率。

本工作首先在Aspen Plus软件上搭建了该耦合系统的热力学仿真模型，随后本工作研究并对比两种聚光太阳能储热介质对系统性能的影响，研究结果表明，导热油和太阳盐相比，使用太阳盐为聚光太阳能储热介质的系统性能更好，储能效率达到了115.9%，往返效率达到了68.2%，㶲效率达到了76.8%，储电折合转化系数达到了92.8%，储能密度达到了5.53 kWh/m3。

此外，本研究还发现低环境温度、高空气汽轮机入口温度及高空气汽轮机入口压力有利于系统储能性能的提高。

关键词：先进绝热压缩空气储能；聚光太阳能辅热；有机朗肯循环；热力学模型；㶲分析doi： 10.19799/ki.2095-4239.2023.0548中图分类号：TK 02 文献标志码：A 文章编号：2095-4239（2023）12-3749-12 Thermodynamic analysis of an advanced adiabatic compressed-air energy storage system coupled with molten salt heat and storage-organic Rankine cycleYIN Hang1, WANG Qiang1, ZHU Jiahua2, LIAO Zhirong2, ZHANG Zinan1, XU Ershu2, XU Chao2(1CGN New Energy Holding Co., Ltd., Beijing 100160, China; 2School of Energy Power and Mechanical Engineering,North China Electric Power University, Beijing 102206, China)Abstract:Advanced adiabatic compressed-air energy storage is a method for storing energy at a large scale and with no environmental pollution. To improve its efficiency, an advanced adiabatic compressed-air energy storage system (AA-CAES+CSP+ORC) coupled with the thermal storage-organic Rankine cycle for photothermal power generation is proposed in this report. In this system, the storage of heat from photothermal power generation is used to solve the problem of limited compression heat in the AA-CAES+CSP+ORC, while the medium- and low-temperature waste heat generation in the organic Rankine cycle power收稿日期：2023-08-18；修改稿日期：2023-09-18。

Kinetics and Thermodynamics of PhaseTransitions相变的动力学和热力学相变，即物质从一个稳定的相态转变为另一个稳定的相态。

对于单一物质的相变，有两个重要的理论：动力学理论和热力学理论。

动力学理论研究相变发生的速度和机制，热力学理论则研究相变发生的原因和过程。

在相变中，热力学和动力学相互联系，共同控制着相变的发生和进行。

一、热力学理论热力学是研究体系宏观状态及其变化的学科，其中相变也是研究的重要内容之一。

相变是由于能量的变化引起的。

在相变过程中，物质体系的各种物理量如温度、压力、物质摩尔数等都发生了变化。

这些变化可以用相变的热力学理论来解释。

1. 热力学参数热力学参数是描述相变过程的关键指标，其中最主要的是相变热。

相变热是在相变过程中吸收或放出的热量，也称为潜热。

相变的热流量为：q = ΔH × n其中，q为相变释放或吸收的热量，ΔH为物质的相变潜热，n为物质摩尔数。

另外，热力学参数还包括相变温度、相变压力、相变熵等。

这些参数与物质的性质、外界条件等有关，不同物质的相变参数也存在差异。

2. 热力学过程相变过程中，热力学过程也是非常重要的。

热力学过程可以分为两类：等温过程和等熵过程。

在等温过程中，相变的压强与热力学参数有关，当达到相变某一温度时，压强会突然发生变化，这时相变会发生。

而在等熵过程中，相变的熵与热力学参数有关。

热力学过程中的熵是体系中无序程度的量度，随相变而发生变化。

3. 热力学状态图热力学状态图是热力学研究中常用的工具，用于描述相变状态的改变。

最常用的状态图是温度-压强图（P-T图）。

P-T图是由温度作为横坐标，压强作为纵坐标，画出不同温度和压强下物质的相变状态。

二、动力学理论动力学理论是研究物质相变过程中的机制和速度的学科，它描述了相变的时间演化过程和物质微观结构的变化。

相变的动力学过程与物质的分子运动、晶格结构和表面缺陷等因素有关。

用于寡核苷酸二级结构预测的热力学数据库研究进展刘哲言;屈武斌;张成岗【摘要】基于核酸分子杂交的生物技术（如PCR）在病原微生物检测、临床诊断等诸多领域中应用广泛，此类技术的可靠性在于寡核苷酸分子与其靶点结合的高稳定性与特异性，而精确预测寡核苷酸与靶分子结合的二级结构是分析其稳定性与特异性的关键。

其中，基于热力学的最近邻模型是寡核苷酸二级结构预测最为可靠的计算方法，但其精确性强烈依赖于精确的热力学参数。

由于寡核苷酸分子二级结构的复杂性，除了完美匹配外，还需要错配、内环、膨胀环、末端摇摆、CNG重复、GU摆动等特殊结构的热力学数据。

本文综述了近年来用于寡核苷酸二级结构预测的有效热力学数据库及相关计算方法，并指出当前热力学数据库的局限及未来发展方向。

%The nucleotide hybridization based molecular biological technologies like PCR have been widely used in many fields, such as pathogenic microorganism detection, clinical diagnosis. And the accurate prediction of secondary structures between oligonucleotide and its binding sites is the key to these technologies. The Nearest-Neighbor Model based on thermodynamics is the most accurate method to predict oligonucleotide secondary structure, and the precision mainly depends on the thermodynamic parameters. Meanwhile, the diversity of secondary structure requires different thermodynamic parameters for different motifs, including perfect matches, mismatches, internal loops, bulge loops, dangling ends, CNG repeats, and GU wobble base pairs. Therefore, this review summarized the current parameter sets available for oligonucleotide secondary structure prediction. We also pointed out thelimitations and future development directions of the thermodynamic database.【期刊名称】《生物信息学》【年(卷),期】2014(000)003【总页数】10页(P196-205)【关键词】寡核苷酸二级结构;热力学数据库;热力学计算【作者】刘哲言;屈武斌;张成岗【作者单位】军事医学科学院放射与辐射医学研究所，蛋白质组学国家重点实验室，全军军事认知与心理卫生研究中心，北京100850;军事医学科学院放射与辐射医学研究所，蛋白质组学国家重点实验室，全军军事认知与心理卫生研究中心，北京100850;军事医学科学院放射与辐射医学研究所，蛋白质组学国家重点实验室，全军军事认知与心理卫生研究中心，北京100850【正文语种】中文【中图分类】Q522近年来，以核酸分子杂交为基础的生物技术如聚合酶链反应、DNA印迹、RNA印迹、芯片杂交等在病原微生物检测、临床诊断中应用广泛，其可靠性依赖于寡核苷酸分子与其靶点结合的高稳定性与特异性，而分析这种结合特性的关键在于寡核苷酸与靶分子结合的二级结构的精确预测，否则会导致假阴性或假阳性的检测结果［1－4］。

Section 10EmulsionsBy Drs. Pardeep K. Gupta, Clyde M. Ofner and Roger L. SchnaareTable of Contents Emulsions (1)Table of Contents (1)Introduction and Background (3)Definitions (3)Types of Emulsions (3)Formation of an Emulsion (4)Determination of Emulsion Type (4)Miscibility or Dilution Test (4)Staining or Dye Test (4)Electrical Conductivity Test (4)Physical State of Emulsions (5)Pharmaceutical Application of Emulsions (5)Formulations (6)Typical Ingredients (6)Drug (6)Oil Phase (6)Aqueous Phase (6)Thickening Agents (6)Sweeteners (6)Preservative (6)Buffer (7)Flavor (7)Color (7)Sequestering Agents (7)Humectants (7)Antioxidants (7)Emulsifiers (7)Guidelines (7)Type of Emulsion Desired (7)Toxicity (8)Method of Preparation (8)Typical Formulas (8)Cod Liver Oil Emulsion (polysaccharide emulsifier) (8)Protective Lotion (divalent soap emulsifier) (8)Benzoyl Benzoate Emulsion (emulsifying wax emulsifier) (8)Barrier Cream (soap emulsifier) (9)Cold Cream (soap emulsifier) (9)All Purpose Cream (synthetic surfactant emulsifier) (9)Emulsifiers (10)Natural Products (10)Polysaccharides (10)Sterols (10)Phospholipids (10)Surfactants (10)Anionic Surfactants (11)Soaps (11)Detergents (11)Cationic Surfactants (11)Nonionic Surfactants (11)Finely Divided Solids (12)Methods to Prepare Emulsions (13)Classical Gum Methods (13)Dry Gum Method (13)Wet Gum Method (13)“In Situ” Soap Method (13)Lime Water/Vegetable Oil Emulsions (13)Other Soaps (13)With Synthetic Surfactants (13)Required HLB of the Oil Phase (14)HLB of Surfactant Mixtures (14)Emulsion Stability (15)Sedimentation or Creaming (15)Factors - Stoke’s Law (15)Droplet Size (15)Density Difference (15)The Gravitational Constant, g (15)Viscosity (15)Breaking or Cracking (16)Thermodynamics of Emulsions (17)Microemulsions (18)References (19)Selected Readings (19)Introduction and BackgroundDefinitionsEmulsions are pharmaceutical preparations consisting of at least two immiscible liquids.Due to the lack of mutual solubility, one liquid is dispersed as tiny droplets in the other liquid to form an emulsion. Therefore,emulsions belong to the group of prepara-tions known as disperse systems.The USP also defines several dosage forms that are essentially emulsions but historically are referred to by other names. For example;Lotions are fluid emulsions orsuspensions intended for external application.Creams are viscous liquid or semi-solid emulsions of either an oil-in-water (O/W) or the water-in-oil (W/O) type. They are ordinarily used topically. The term cream is applied most frequently to soft, cosmetically acceptable types of preparations.Microemulsions are emulsions withextremely small droplet sizes and usually require a high concentration of surfactant for stability. They can also be regarded as isotropic, swollen micellar systems.Multiple emulsions are emulsions that have been emulsified a second time,consequently containing three phases. They may be water-in-oil-in-water (W/O/W) or oil-in-water-in-oil (O/W/O).Fluid emulsions are generally composed of discrete, observable liquid droplets in a fluid media, while semi-solid emulsions generally have a complex, more disorganized structure.The liquid which is dispersed as droplets iscalled as the dispersed , discontinuous or internal phase, and the liquid in which thedispersion is suspended is the dispersion medium or the continuous or external phase.For example, if olive oil is shaken with water,it breaks up into small globules andbecomes dispersed in water. In this case the oil is the internal phase, and water is the external phase.The dispersed particles or globules can range in size from less than 1 µm up to 100 µm. An emulsion is rarely a monodis-perse system, e.g., all the particles are rarely of the same size. A typical emulsion contains a distribution of many sizes, making it a polydisperse system.Types of EmulsionsBased on the nature of the internal (or exter-nal) phase, emulsions are of two types; oil-in-water (O/W) and water-in-oil (W/O). In an O/W type the oil phase is dispersed in the aqueous phase, while the opposite is true in W/O emulsions. Figure 1 depicts these two types of emulsions.Figure 1: Representation of Two Types of EmulsionsO/W Emulsion W/O Emulsion (water black)(oil white)When two immiscible phases are shaken together, either type of emulsion can result.However, this result is not random, but is dependent primarily on two factors; most importantly the type of emulsifier used and secondly the relative ratio of the aqueous and oil phases (phase volume ratio). The emulsifiers and their role in the type of emulsion are discussed in detail later in this chapter.In terms of the phase volume ratio, the percent of the internal phase is generally less than 50%, although emulsions can have internal phase volume percent as high as 75%. Uniform spheres, when packed in a rhombohedral geometry occupy approxi-mately 75% of the total volume. Phase volumes higher than 75% require that the droplets of dispersed phase be distorted into geometric shapes other than perfect spheres. Although it is rare to find emulsions with higher than 75% internal volume, phase volumes of over 90% have been reportedin literature.Formation of an EmulsionWhen two immiscible liquids are placedin contact with each other, they form two separate layers. The liquid with higher density forms the lower layer and the one with lower density forms the upper layer. When this two-layer system is shaken vigorously, one of the layers disperses in the other liquid forming an unstable emul-sion. If left unstirred, the dispersed phase comes together and coalesces into larger drops until the layers become separate again. If no other ingredient is added, this process of separation is usually completein a matter of a few minutes to a few hours. Therefore, a liquid dispersion is inherently an unstable system.However, when an emulsifier is present in the system, it reduces the interfacial tension between the two liquids and forms a physical barrier between droplets, hence lowers the total energy of the system(see discussion on Thermodynamics of Emulsions), thereby reducing the tendency of the droplets to come together and coalesce. Consequently, the globules ofthe internal phase may remain intact for long periods of time, forming a “stable”emulsion. It should be noted, however,that even with an emulsifier, an emulsionis a thermodynamically unstable system and will eventually revert to bulk phases. The time required for this process is determined by kinetics.Determination of Emulsion TypeSeveral tests can be used to determine whether a given emulsion is an O/W or W/O type. These are as follows:Miscibility or Dilution TestThis method is based on the fact that an emulsion can be diluted freely with a liquid of the same kind as its external phase. Typically, a small amount of the emulsion is added to a relatively large volume of water and the mixture is stirred. If the emulsion disperses in water, it is considered to bean O/W type emulsion. If, however, the emulsion remains undispersed, it is a W/O type emulsion.Staining or Dye TestThis test is based on the fact that if a dye is added to an emulsion and the dye is soluble only in the internal phase, the emulsion contains colored droplets dispersed inthe colorless external phase. This can be confirmed by observing a drop of emulsion under a low power microscope. An example of such a dye is scarlet red, which is an oil soluble dye. When added to an O/W type emulsion, followed by observation under the microscope, bright red colored oil drops in an aqueous phase can be seen clearly. Electrical Conductivity TestThis test is based on the fact that onlythe aqueous phase can conduct electrical current. Thus, when a voltage is applied across a liquid, a significant amount of electrical current will flow only when the path of the current is through a continuous aqueous phase. Since oil is a non-conductor of electricity, when tested for conductivity, a W/O type emulsion will show insignificant current flow.Often times a single test may not be conclu-sive. In such circumstances, more than one test may need to be carried out to confirm the emulsion type.Physical State of EmulsionsMost emulsions are either liquid or semi-solid at room temperature. In general, due to their high viscosity, the semi-solid emulsions are relatively more physically stable. Liquid emulsions are more commonly compounded for internal use, while semisolids are usually for external use or for use in body cavities (rectal or vaginal).Other terms commonly used to describe emulsions are lotion and cream . The term lotion refers to a disperse system that flows freely under the force of gravity. A cream is a product that does not flow freely under the force of gravity. It should be noted, however,that these terms are meaningful only when the product is at room temperature. A cream product may behave like a lotion with a temperature increase of a few degrees. The physical state of the final product is also influenced by its intended use. For example suntan lotions are dispensed as lotions instead of creams because they need to be applied on large body surface. Lotion form makes it easy to pour and spread the product. For application over a small portion of skin, a cream is the preferred form of an emulsion.Pharmaceutical Applications of Emulsions There are several reasons for formulation of a product as an emulsion. These include the following:•To disguise the taste or smell of oils or oil soluble drugs. These emulsions are normally O/W types with the aqueous phase containing sweeteners and flavoring agents to mask the poor taste of oils. An O/W type of emulsionalso makes it easy to rinse off the residual dose from the mouth and does not leave an oily taste. Mineral oil and cod liver oil are emulsified for this reason.•To improve the absorption of poorly soluble drugs. Oil soluble drugs may not be soluble enough to be absorbed efficiently. An example of such a drug is cyclosporin, which is dispensed as a microemulsion. •To deliver nutrients and vitamins by intravenous injection. Intralipid is an emulsion product for administering an oil by the IV route.•To serve as a vehicle for the topical administration of a variety of drugs.Kb is the binding constant of the preservative with the surfactantSweeteners are added to emulsions to produce a more palatable preparation, toand sorbitol.AntioxidantsAntioxidants are often added to prevent oxidation of vegetable oils and/or the active drug.Table 1. Typical AntioxidantsEmulsifiersEmulsifiers are substances that have the ability to concentrate at the surface of a liquid or interface of two liquids, many of them reducing the surface or interfacial tension. Those emulsifiers that reduce surface tension are also called surfactants .Emulsifiers in general are discussed inmore detail in a later section of this chapter.GuidelinesBefore selecting a formula for an emulsion,one needs to consider several factors.These are listed below.Type of Emulsion DesiredSince O/W emulsions are more pleasant to touch and swallow, they are generally preferred. Preparations for internal use are almost always O/W type products.Externally used emulsions may be of either type. Creams and lotions that are used primarily to provide oil to the skin need to be W/O due to high concentration of oils in these preparations.The equation shows that the effective concentration in the aqueous phase will always be a fraction of the total concentration.Solvents such as alcohol, glycerin and propylene glycol are often used as apreservative at concentrations approaching 10%. See Table 5, Typical Preservatives in Section 9 of this manual.BufferMany chemical buffer systems have been used in emulsions to control the pH. The optimal pH is chosen to ensure activity of the emulsifier, control stability of the drug and to ensure compatibility and stability of other ingredients.FlavorFlavoring agents enhance patient accept-ance of the product, which is particularly important for pediatric patients.ColorColorants are intended to provide a more aesthetic appearance to the final product.Emulsions are generally not colored with the exception of some topical products. Sequestering AgentsSequestering agents may be necessary to bind metal ions in order to control oxidative degradation of either the drug or other ingredients. HumectantsHumectants are water soluble polyols that prevent or hinder the loss of water from semi-solid emulsions, i.e., topical creams.They also contribute to the solvent proper-ties of the aqueous phase and contribute to the sweetness of oral preparations. The most common are glycerin, propylene glycolToxicityMost emulsifiers are not suitable for internal use. For orally given emulsions, acacia is commonly used as an emulsifying agent.Taste is another factor in selection ofingredients. In this regard, most polysaccha-rides are tasteless and, hence, suitable from a taste standpoint.Method of PreparationSoaps and acacia are excellent forextemporaneous preparations. While soaps allow the preparation to be made by simply mixing the ingredients and shaking, acacia can be used in a pestle and mortar to prepare emulsions.Typical FormulasCod Liver Oil Emulsion (polysaccharide emulsifier)Preparationing a ratio of 4:2:1 for oil, water and gums(both combined), prepare a primary emulsion by dry gum method. (See Methods to Prepare Emulsions on page 13.)2.Dilute with water to a flowable consistency andpour in a measuring device.3.Add alcohol diluted with equal volume of water,followed by the benzaldehyde and saccharin sodium.4.Dilute to volume (200 mL) with waterPreparation1.Add benzyl benzoate to the wax in a beakerand heat in a water bath until the wax melts and the temperature reaches 60°C.2.In a separate beaker, add an appropriate volumeof water and heat to the same temperature.3.Add the water to the oil phase with continuousstirring.4.Continue to stir until the mixture begins tothicken and cools to room temperature.Preparation1.Mix the two powders in a mortar and trituratewell, taking care that all the lumps and large particles have been reduced.2.Then add oil slowly with constant trituration untilall the oil has been added. Triturate to form a smooth paste.3.Then add the limewater and triturate briskly toform the emulsion.Note: The emulsifier, calcium oleate (from limewater and olive oil), preferentially forms O/W emulsions.Protective Lotion (divalent soap emulsifier)Benzyl Benzoate Emulsion (emulsifying wax emulsifier)Preparation1.Mix the paraffins, cetostearyl alcohol andstearic acid in a beaker and heat in a water bath to about 60°C.2.Heat water and chlorocresol together to thesame temperature.3.Add the aqueous phase to the oil phase andstir until congealed and cooled to room temperature.Note:The emulsifier is triethanolamine stearate formed in situ.Preparation1.Melt the sorbitan monostearate and stearicacid in the liquid paraffin and cool to 60°C. 2.Mix the sorbitol solution, preservatives,polysorbate 60 and water and heat to the temperature of the oil mixture.3.Add the aqueous solution to the oil phase andstir until it has congealed and cooled to room temperature.Note:Propylene glycol serves as a solvent for the preservatives.Preparation1.Mix and melt the wax and paraffin together.2.Dissolve borax in water and heat both containerson a water bath to 70°C.3.Add the aqueous phase to the oil phase andstir until it has congealed and cooled to room temperature.Note:The fatty acid in white beeswax reacts with borax (sodium borate) to make a sodium soap which acts as an W/O type emulsifier.Barrier Cream (soap emulsifier)All Purpose Cream (synthetic surfactant emulsifier)Cold Cream (soap emulsifier)Surfactants or surface active agents are molecules that consist of two distinct parts,a hydrophobic tail and a hydrophilic head group. They are generally classified based on the hydrophilic properties of the head group (ionic charge, polarity, etc.). Since the hydrophobic chains do not vary much in their properties, the nature of surfactants is dependent mainly on the head group structure.A common problem with sterol-containing emulsifiers is that being complex mixtures of natural substances, they are prone to variability in their quality and, hence, performance. Also, these agents usually contain some degree of an odor, which varies with the purity and source. Some semi-synthetic substitutes are available that seek to overcome some of the problems associated with these agents.There are of basically three types of emulsifiers: natural products, surface active agents (surfactants), and finely divided solids. Based on whether a stable emulsion can be produced, emulsifiers are also classified either as primary emulsifying agents which produce stable emulsions by themselves, or secondary emulsifying agents (stabilizers) which help primary emulsifiers to form a more stable emulsion.of cholesterol. Cholesterol itself is a very efficient emulsifier and produces W/O type emulsions. Consequently, its use is limited to topical preparations such as Hydrophilic Petrolatum USP which readily absorbs water forming a W/O cream. Woolfat or lanolin contains a considerable amount of choles-terol esters and can absorb up to 50% of its own weight of water.This group of emulsifiers, which numbers in the hundreds, contain a polyoxyethylene chain as the polar head group. They arenonionic and, thus, are compatible with ionic compounds and are less susceptible to pH changes. There are several such surfactants official in the USP/NF , typified by sorbitan monooleate (a partial ester of lauric acid with sorbitol), polysorbate 80(polyoxyethyl-ene 20 sorbitan monooleate) which contains 20 oxyethylene units copolymerized sorbitanAmine soaps consist of an amine, such as triethanolamine, in the presence of a fatty acid. These surfactants are viscous solutions and produce O/W type emulsions. They offer the advantage that the final pH of the preparations is generally close to neutral,and, therefore, allows their use on skin for extended periods of time.monooleate) and polyoxyl 40 stearate(a mixture of stearic acid esters with mixed poloxyethylene diols equivalent to about40 oxyethylene units).The large number of nonionic emulsifiers results from the large number of possible combinations of various alkyl groups with polyoxyethylene chains of varying lengths. Compounds with saturated and/or large alkyl groups, such as stearyl, tend to be solids or semisolids while oleyl (also large, but unsaturated) compounds tend to be liquids. Also, the longer the polyoxyethylene chain, the higher the melting point.To characterize such a large number of compounds, they are each assigned an HLB number. The HLB number or hydrophile-lipophile balance, is a measure of the relative hydrophilic vs lipophilic character of the molecule as determined by the relative size of the polyoxyethylene chain vs the alkyl group. HLB numbers range from 0 for a pure hydrocarbon to 20 for a pure poly-oxyethylene chain. Some typical valuesare listed in Table 3.Ionic surfactants, such as sodium lauryl sulfate, were not included in the original definition of the HLB system but have been included as the HLB system was developed. The HLB number of 40 for sodium lauryl sulfate is outside of the range of 0 to 20 and simply means that sodium lauryl sulfate is much more soluble or hydrophilic thana pure polyoxyethylene chain.Table 3. Typical HLB Numbersof EmulsifiersFinely Divided SolidsFinely divided solids function as emulsifiers because of their small particle size. Fine particles tend to concentrate at a liquid-liquid interface, depending on their wetability, and form a particulate film around the dispersed droplets. They are seldom used as the primary emulsifier.phase. The emulsion type will depend on the type of soap formed.Basically the formula is divided into anoil phase and an aqueous phase with the ingredients dissolved in their proper phases (oil or water). The surfactant(s) is added to the phase in which it is most soluble. The oil phase is then added to the aqueous phase with mixing, and the coarse mixture passed through an homogenizer.When waxes or waxy solids are included in the formulation, the use of heat is necessary,as described above.Required HLB of the Oil Phase.It has been found that various oils and lipid materials form stable emulsions withsurfactants that have a certain HLB value.This HLB value is called the required HLB of the oil or lipid. Theoretically, any surfac-tant with the required HLB would produce a stable emulsion with the indicated oil or lipid. Some examples are given in Table 4.Table 4. Required HLB Values for Typical Oils and LipidsHLB of Surfactant MixturesIt may be difficult to find a surfactant with the exact HLB number required for a given oil phase in an emulsion. Fortunately, the HLB numbers have been shown to be additive for a mixture of surfactants. Thus, if one required a surfactant with a HLB of 10, one could use a mixture of sorbitan monooleate (HLB = 4.7) and polysorbate 80 (HLB = 15.6). Such a mixture can be calculated on the basis of a simple weighted average as follows.Suppose 5 g of surfactant mixture is required. Let ␹= the g of sorbitanmonooleate, then 5 ␹= the g of polysorbate 80 required.␹(4.7)+(5- ␹)(15.6) = 10(5)4.7 ␹+ 78.0- 15.6␹= 10(5)10.9␹= 28␹= 2.57 and 5- ␹= 2.43Thus a mixture of 2.57 g of sorbitanmonooleate and 2.43 g of polysorbate 80would have a HLB of 10.Griffin 2described an experimental approach for the formulation of emulsions using synthetic emulsifiers.1.Group the ingredients on the basis of theirsolubilities in the aqueous and oil phases.2.Determine the type of emulsion required andcalculate an approximate required HLB value.3.Blend a low HLB emulsifier and a high HLBemulsifier to the required HLB.4.Dissolve the oil soluble ingredients and the lowHLB emulsifier in the oil phase. Heat, if necessary,to approximately 5 to 10°over the melting point of the highest melting ingredient or to a maximum temperature of 70 to 80°C.5.Dissolve the water soluble ingredients (exceptacids and salts) in a sufficient quantity of water.6.Heat the aqueous phase to a temperature whichis 3 to 5°higher than that of the oil phase.7.Add the aqueous phase to the oil phase withsuitable agitation.8.If acids or salts are employed, dissolve them inwater and add the solution to the cold emulsion.9.Examine the emulsion and make adjustments inthe formulation if the product is unstable. It may be necessary to add more emulsifier, change to an emulsifier with a slightly higher or lower HLB value or to use an emulsifier with different chemical characteristics.In addition to chemical degradation of various components of an emulsion, which can happen in any liquid preparation, emulsions are subject to a variety of physical instabilities. Sedimentation or Creaming Factors - Stoke’s LawCreaming usually occurs in a liquid emulsion since the particle size is generally greater than that of a colloidal dispersion. The rate is described by Stoke’s Law for a single particle settling in an infinite container under the force of gravity as follows:d ␹=d 2(␳2- ␳1)gdt 18␩where:d ␹/d t= the sedimentation rate in distance/time d = droplet diameter ␳2= droplet density␳1= emulsion medium density g = acceleration due to gravity ␩= viscosity of the emulsion mediumSince for most oil phases, ␳2< ␳1, then sedimentation will be negative, i.e., the oil droplets will rise forming a creamy whitelayer. While Stoke’s Law does not describe creaming quantitatively in an emulsion, it does provide a clear collection of factors and their qualitative influence on creaming.Droplet SizeReducing droplet size can have a significant effect on creaming rate. Since the diameter is squared in Stoke’s Law, a reduction in size by ¹⁄₂will reduce the creaming rate by (¹⁄₂)2or a factor of 4.Emulsion StabilityDensity DifferenceIf the difference in density between the emulsion droplet and the external phase can be matched, the creaming rate could be reduced to zero. This is almost impossi-ble with most oils and waxy solids used in emulsions.The Gravitational Constant, gThis parameter is not of much interest since it can not be controlled or changed unless in space flight.ViscosityViscosity turns out to be the most readily controllable parameter in affecting the creaming rate. While the viscosity in Stoke’s Law refers to the viscosity of the fluid through which a droplet rises, in reality the viscosity that controls creaming is the viscosity of the entire emulsion. Thus, doubling the viscosity of an emulsion will decrease the creaming rate by a factor of 2.There are three major ways to increase the viscosity of an emulsion:•Increase the concentration of the internal phase•Increase the viscosity of the internal phase by adding waxes and waxy solids to the oil phase.•Increase the viscosity of the external phase by adding a viscosity building agent. Most of the suspending agents described in the Suspensions Section in this manual have been used for this purpose.Creaming does not usually occur in a semi-solid emulsion.Breaking or CrackingThis problem arises when the dispersed globules come together and coalesce to form larger globules. As this process continues, the size of the globules increases, making it easier for them to coalesce. This eventually leads to separation of the oil and water phases. For cracking to occur, the barrier that normally holds globules apart has to break down. Some of the factorsthat contribute to cracking are as follows:•Insufficient or wrong kind of emulsifier in the system.•Addition of ingredients that inactivate the emulsifier. Incompatible ingredients may show their effect over a period of time.An example of such an incompatibilitywill be to use large anions in thepresence of cationic emulsifier.•Presence of hardness in water. The calcium and magnesium present in hard water can replace a part of the alkalisoap with divalent soap. Since thesesoaps form different kinds of emulsions, phase inversion usually takes place.•Low viscosity of the emulsion •Exposure to high temperatures can also accelerate the process of coalescence.This is due to the fact that at an elevated temperature, the collisions between theglobules can overcome the barrier tocoalescence, thereby increasing thechance that a contact between twoparticles will lead to their fusion.Temperature may have an adverse effect on the activity of emulsifiers, particularly if these are proteinaceous in nature.However, this usually happens at temper-atures higher than 50°C. Conversely, areduction in temperature to the point that the aqueous phase freezes also will break the emulsion.•An excessive amount of the internal phase makes an emulsion inherently less stable because there is a greater chance of globules coming together.Cracking is the most serious kind of physical instability of an emulsion. Cracking of an emulsion usually renders it useless. In creams, the problem of cracking may show up as tearing. This is a process where one phase separates and appears like drops on top of the cream.The basic difference between creamingand cracking is that the globules in creaming do not coalesce to form larger particles. Therefore, creaming is a less serious problem and most preparations that show creaming can be shaken to redisperse the internal phase to its original state. A com-mon example of creaming is the formation of cream on top of whole milk due to collection of emulsified fat of the milk. This problem is solved by homogenizing the milk to reduce the particle size of dispersed fat, thereby reducing the rate at which they travel tothe surface.。

The Thermodynamics of the Earths Atmosphere The Earth's atmosphere is a complex system that interacts with the planet's surface, oceans, and biosphere. The study of the thermodynamics of the atmosphere is essential in understanding the behavior of this system and how it affects our planet. Thermodynamics is the study of the relationships between heat, energy, and work. In the context of the Earth's atmosphere, thermodynamics helps us understand the processes that govern the movement of air, the formation of weather patterns, and the distribution of energy throughout the system.One of the key principles of thermodynamics is the conservation of energy. This principle states that energy cannot be created or destroyed; it can only be transferred or converted from one form to another. In the Earth's atmosphere, energy is transferred through a variety of processes, including radiation, conduction, and convection. Radiation is the transfer of energy through electromagnetic waves, such as those from the sun. Conduction is the transfer of energy through direct contact, such as when the ground heats the air above it. Convection is the transfer of energy through the movement of fluids, such as when warm air rises and cool air sinks.Another important principle of thermodynamics is the second law of thermodynamics, which states that the total entropy of a closed system always increases over time. Entropy is a measure of the disorder or randomness of a system. In the Earth's atmosphere, entropy increases as energy is transferred from one place to another. This means that the atmosphere tends towards a state of maximum disorder, which can lead to the formation of weather patterns and other complex phenomena.The thermodynamics of the Earth's atmosphere also plays a crucial role in the global climate system. The atmosphere acts as a greenhouse, trapping heat from the sun and regulating the temperature of the planet. This is known as the greenhouse effect, and it is essential for life on Earth. However, human activities such as the burning of fossil fuels have increased the concentration of greenhouse gases in the atmosphere, leading to an enhanced greenhouse effect and global warming. Understanding the thermodynamics ofthe atmosphere is therefore crucial in addressing the challenges of climate change and developing strategies to mitigate its impacts.From a human perspective, the thermodynamics of the Earth's atmosphere has a profound impact on our daily lives. Weather patterns such as hurricanes, tornadoes, and thunderstorms are all driven by the movement of air and the transfer of energy through the atmosphere. These phenomena can have devastating effects on communities, causing loss of life and property damage. Understanding the thermodynamics of the atmosphere can help us predict and prepare for these events, improving our ability to respond and recover from natural disasters.In conclusion, the study of the thermodynamics of the Earth's atmosphere is essential in understanding the behavior of this complex system and its impact on our planet. Through the principles of conservation of energy and the second law of thermodynamics, we can gain insights into the processes that govern the movement of air, the formation of weather patterns, and the distribution of energy throughout the system. From a human perspective, this knowledge is critical in predicting and preparing for natural disasters and addressing the challenges of climate change. As we continue to explore the mysteries of our planet's atmosphere, the principles of thermodynamics will undoubtedly play a central role in our understanding of this fascinating and complex system.。

2021年第1期【摘要】运用一维仿真软件建立质子交换膜燃料电池液冷系统模型，研究了不同节温器布置形式对系统的性能影响。

对某额定功率30kW 的燃料电池发动机在4个不同工况点进行液冷系统散热特性仿真：在节温器一进两出的布置形式下仿真结果与试验数据基本一致，电堆出口温度仿真值与实测值相对误差分别为0.5%、1.5%、2.4%、4.9%；节温器两进一出的布置形式下液冷系统中冷却液温度变化平缓而均匀，前10s 和第10~50s 之间的温度变化率之差较一进两出形式低36.85%，更有利于电堆的长期高效运行。

主题词：节温器质子交换膜燃料电池一维仿真液冷系统中图分类号：TM911.42文献标识码：ADOI:10.19620/ki.1000-3703.20200355Effects of Thermostat Layouts on Cooling Performance of ProtonExchange Membrane Fuel Cell StacksCheng Zifeng 1,2,Li Ming 1,2,Guo Qin 3,Ren Yan 4,Qin Guihe 3（1.State Key Laboratory of Automotive Simulation and Control,Jilin University,Changchun 130022;2.College of Automotive Engineering,Jilin University,Changchun 130022;3.College of Computer Science and Technology,Jilin University,Changchun 130022;4.Henan College of Forestry,Luoyang 471000）【Abstract 】In this research,one-dimensional simulation software is used to establish the liquid cooling system model of Proton Exchange Membrane Fuel Cell (PEMFC),and the effects of different thermostat layouts on the performance of the system are studied.Heat dissipation characteristics of a liquid cooling system for a fuel cell engine with rated power of 30kW are simulated at four different operating points,the results are basically consistent with test data under one-in-two-out arrangement of the thermostat.The relative errors between the simulated value and the measured value of the stack outlet temperature are 0.5%,1.5%,2.4%and 4.9%respectively,whereas the change of the coolant temperature in the liquid cooling system is gentle and even under the two-in-one-out arrangement of the thermostat.The difference of temperature change rate between the first 10seconds and the range from the 10th second to the 50th second is 36.85%lower than thatof one-in-two-out arrangement,which is more conducive to the long-term and efficient operation of the stack.Key words:Thermostat,Proton exchange membrane fuel cell,One-dimensional simulation,Liquid cooling system程子枫1,2李明1,2郭勤3任雁4秦贵和3（1.吉林大学，汽车仿真与控制国家重点实验室，长春130022；2.吉林大学，汽车工程学院，长春130022；3.吉林大学，计算机科学与技术学院，长春130022；4.河南林业职业学院，洛阳471000）*基金项目：吉林省科技厅技术攻关项目（20190302120GX ）；汽车仿真与控制国家重点实验室自由探索项目（ascl-zytsxm-202029）。

New1H-Pyrazole-Containing Polyamine Receptors Able ToComplex L-Glutamate in Water at Physiological pH ValuesCarlos Miranda,†Francisco Escartı´,‡Laurent Lamarque,†Marı´a J.R.Yunta,§Pilar Navarro,*,†Enrique Garcı´a-Espan˜a,*,‡and M.Luisa Jimeno†Contribution from the Instituto de Quı´mica Me´dica,Centro de Quı´mica Orga´nica Manuel Lora Tamayo,CSIC,C/Juan de la Cier V a3,28006Madrid,Spain,Departamento de Quı´mica Inorga´nica,Facultad de Quı´mica,Uni V ersidad de Valencia,c/Doctor Moliner50, 46100Burjassot(Valencia),Spain,and Departamento de Quı´mica Orga´nica,Facultad deQuı´mica,Uni V ersidad Complutense de Madrid,A V plutense s/n,28040Madrid,SpainReceived April16,2003;E-mail:enrique.garcia-es@uv.esAbstract:The interaction of the pyrazole-containing macrocyclic receptors3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.111,14]-octacosa-1(27),11,14(28),24-tetraene1[L1],13,26-dibenzyl-3,6,9,12,13,16,-19,22,25,26-decaazatricyclo-[22.2.1.111,14]-octacosa-1(27),11,14(28),24-tetraene2[L2],3,9,12,13,16,22,-25,26-octaazatricyclo-[22.2.1.111,14]-octacosa-1(27),11,14(28),24-tetraene3[L3],6,19-dibenzyl-3,6,9,12,13,-16,19,22,25,26-decaazatricyclo-[22.2.1.111,14]-octacosa-1(27),11,14(28),24-tetraene4[L4],6,19-diphenethyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.111,14]-octacosa-1(27),11,14(28),24-tetraene5[L5],and 6,19-dioctyl-3,6,9,12,13,16,19,22,25,26-decaazatricyclo-[22.2.1.111,14]-octacosa-1(27),11,14(28),24-tetra-ene6[L6]with L-glutamate in aqueous solution has been studied by potentiometric techniques.The synthesis of receptors3-6[L3-L6]is described for the first time.The potentiometric results show that4[L4]containing benzyl groups in the central nitrogens of the polyamine side chains is the receptor displaying the larger interaction at pH7.4(K eff)2.04×104).The presence of phenethyl5[L5]or octyl groups6[L6]instead of benzyl groups4[L4]in the central nitrogens of the chains produces a drastic decrease in the stability[K eff )3.51×102(5),K eff)3.64×102(6)].The studies show the relevance of the central polyaminic nitrogen in the interaction with glutamate.1[L1]and2[L2]with secondary nitrogens in this position present significantly larger interactions than3[L3],which lacks an amino group in the center of the chains.The NMR and modeling studies suggest the important contribution of hydrogen bonding andπ-cation interaction to adduct formation.IntroductionThe search for the L-glutamate receptor field has been andcontinues to be in a state of almost explosive development.1 L-Glutamate(Glu)is thought to be the predominant excitatory transmitter in the central nervous system(CNS)acting at a rangeof excitatory amino acid receptors.It is well-known that it playsa vital role mediating a great part of the synaptic transmission.2However,there is an increasing amount of experimentalevidence that metabolic defects and glutamatergic abnormalitiescan exacerbate or induce glutamate-mediated excitotoxic damageand consequently neurological disorders.3,4Overactivation ofionotropic(NMDA,AMPA,and Kainate)receptors(iGluRs)by Glu yields an excessive Ca2+influx that produces irreversible loss of neurons of specific areas of the brain.5There is much evidence that these processes induce,at least in part,neuro-degenerative illnesses such as Parkinson,Alzheimer,Huntington, AIDS,dementia,and amyotrophic lateral sclerosis(ALS).6In particular,ALS is one of the neurodegenerative disorders for which there is more evidence that excitotoxicity due to an increase in Glu concentration may contribute to the pathology of the disease.7Memantine,a drug able to antagonize the pathological effects of sustained,but relatively small,increases in extracellular glutamate concentration,has been recently received for the treatment of Alzheimer disease.8However,there is not an effective treatment for ALS.Therefore,the preparation of adequately functionalized synthetic receptors for L-glutamate seems to be an important target in finding new routes for controlling abnormal excitatory processes.However,effective recognition in water of aminocarboxylic acids is not an easy task due to its zwitterionic character at physiological pH values and to the strong competition that it finds in its own solvent.9†Centro de Quı´mica Orga´nica Manuel Lora Tamayo.‡Universidad de Valencia.§Universidad Complutense de Madrid.(1)Jane,D.E.In Medicinal Chemistry into the Millenium;Campbell,M.M.,Blagbrough,I.S.,Eds.;Royal Society of Chemistry:Cambridge,2001;pp67-84.(2)(a)Standaert,D.G.;Young,A.B.In The Pharmacological Basis ofTherapeutics;Hardman,J.G.,Goodman Gilman,A.,Limbird,L.E.,Eds.;McGraw-Hill:New York,1996;Chapter22,p503.(b)Fletcher,E.J.;Loge,D.In An Introduction to Neurotransmission in Health and Disease;Riederer,P.,Kopp,N.,Pearson,J.,Eds.;Oxford University Press:New York,1990;Chapter7,p79.(3)Michaelis,E.K.Prog.Neurobiol.1998,54,369-415.(4)Olney,J.W.Science1969,164,719-721.(5)Green,J.G.;Greenamyre,J.T.Prog.Neurobiol.1996,48,613-63.(6)Bra¨un-Osborne,H.;Egebjerg,J.;Nielsen,E.O.;Madsen,U.;Krogsgaard-Larsen,P.J.Med.Chem.2000,43,2609-2645and references therein.(7)(a)Shaw,P.J.;Ince,P.G.J.Neurol.1997,244(Suppl2),S3-S14.(b)Plaitakis,A.;Fesdjian,C.O.;Shashidharan,S Drugs1996,5,437-456.(8)Frantz,A.;Smith,A.Nat.Re V.Drug Dico V ery2003,2,9.Published on Web12/30/200310.1021/ja035671m CCC:$27.50©2004American Chemical Society J.AM.CHEM.SOC.2004,126,823-8339823There are many types of receptors able to interact with carboxylic acids and amino acids in organic solvents,10-13yielding selective complexation in some instances.However,the number of reported receptors of glutamate in aqueous solution is very scarce.In this sense,one of the few reports concerns an optical sensor based on a Zn(II)complex of a 2,2′:6′,2′′-terpyridine derivative in which L -aspartate and L -glutamate were efficiently bound as axial ligands (K s )104-105M -1)in 50/50water/methanol mixtures.14Among the receptors employed for carboxylic acid recogni-tion,the polyamine macrocycles I -IV in Chart 1are of particular relevance to this work.In a seminal paper,Lehn et al.15showed that saturated polyamines I and II could exert chain-length discrimination between different R ,ω-dicarboxylic acids as a function of the number of methylene groups between the two triamine units of the receptor.Such compounds were also able to interact with a glutamic acid derivative which has the ammonium group protected with an acyl moiety.15,16Compounds III and IV reported by Gotor and Lehn interact in their protonated forms in aqueous solution with protected N -acetyl-L -glutamate and N -acetyl-D -glutamate,showing a higher stability for the interaction with the D -isomer.17In both reports,the interaction with protected N -acetyl-L -glutamate at physiological pH yields constants of ca.3logarithmic units.Recently,we have shown that 1H -pyrazole-containing mac-rocycles present desirable properties for the binding of dopam-ine.18These polyaza macrocycles,apart from having a highpositive charge at neutral pH values,can form hydrogen bonds not only through the ammonium or amine groups but also through the pyrazole nitrogens that can behave as hydrogen bond donors or acceptors.In fact,Elguero et al.19have recently shown the ability of the pyrazole rings to form hydrogen bonds with carboxylic and carboxylate functions.These features can be used to recognize the functionalities of glutamic acid,the carboxylic and/or carboxylate functions and the ammonium group.Apart from this,the introduction of aromatic donor groups appropriately arranged within the macrocyclic framework or appended to it through arms of adequate length may contribute to the recognition event through π-cation interactions with the ammonium group of L -glutamate.π-Cation interactions are a key feature in many enzymatic centers,a classical example being acetylcholine esterase.20The role of such an interaction in abiotic systems was very well illustrated several years ago in a seminal work carried out by Dougherty and Stauffer.21Since then,many other examples have been reported both in biotic and in abiotic systems.22Taking into account all of these considerations,here we report on the ability of receptors 1[L 1]-6[L 6](Chart 2)to interact with L -glutamic acid.These receptors display structures which differ from one another in only one feature,which helps to obtain clear-cut relations between structure and interaction(9)Rebek,J.,Jr.;Askew,B.;Nemeth,D.;Parris,K.J.Am.Chem.Soc.1987,109,2432-2434.(10)Seel,C.;de Mendoza,J.In Comprehensi V e Supramolecular Chemistry ;Vogtle,F.,Ed.;Elsevier Science:New York,1996;Vol.2,p 519.(11)(a)Sessler,J.L.;Sanson,P.I.;Andrievesky,A.;Kral,V.In SupramolecularChemistry of Anions ;Bianchi,A.,Bowman-James,K.,Garcı´a-Espan ˜a,E.,Eds.;John Wiley &Sons:New York,1997;Chapter 10,pp 369-375.(b)Sessler,J.L.;Andrievsky,A.;Kra ´l,V.;Lynch,V.J.Am.Chem.Soc.1997,119,9385-9392.(12)Fitzmaurice,R.J.;Kyne,G.M.;Douheret,D.;Kilburn,J.D.J.Chem.Soc.,Perkin Trans.12002,7,841-864and references therein.(13)Rossi,S.;Kyne,G.M.;Turner,D.L.;Wells,N.J.;Kilburn,J.D.Angew.Chem.,Int.Ed.2002,41,4233-4236.(14)Aı¨t-Haddou,H.;Wiskur,S.L.;Lynch,V.M.;Anslyn,E.V.J.Am.Chem.Soc.2001,123,11296-11297.(15)Hosseini,M.W.;Lehn,J.-M.J.Am.Chem.Soc.1982,104,3525-3527.(16)(a)Hosseini,M.W.;Lehn,J.-M.Hel V .Chim.Acta 1986,69,587-603.(b)Heyer,D.;Lehn,J.-M.Tetrahedron Lett.1986,27,5869-5872.(17)(a)Alfonso,I.;Dietrich,B.;Rebolledo,F.;Gotor,V.;Lehn,J.-M.Hel V .Chim.Acta 2001,84,280-295.(b)Alfonso,I.;Rebolledo,F.;Gotor,V.Chem.-Eur.J.2000,6,3331-3338.(18)Lamarque,L.;Navarro,P.;Miranda,C.;Ara ´n,V.J.;Ochoa,C.;Escartı´,F.;Garcı´a-Espan ˜a,E.;Latorre,J.;Luis,S.V.;Miravet,J.F.J.Am.Chem.Soc .2001,123,10560-10570.(19)Foces-Foces,C.;Echevarria,A.;Jagerovic,N.;Alkorta,I.;Elguero,J.;Langer,U.;Klein,O.;Minguet-Bonvehı´,H.-H.J.Am.Chem.Soc.2001,123,7898-7906.(20)Sussman,J.L.;Harel,M.;Frolow,F.;Oefner,C.;Goldman,A.;Toker,L.;Silman,I.Science 1991,253,872-879.(21)Dougherty,D.A.;Stauffer,D.A.Science 1990,250,1558-1560.(22)(a)Sutcliffe,M.J.;Smeeton,A.H.;Wo,Z.G.;Oswald,R.E.FaradayDiscuss.1998,111,259-272.(b)Kearney,P.C.;Mizoue,L.S.;Kumpf,R.A.;Forman,J.E.;McCurdy,A.;Dougherty,D.A.J.Am.Chem.Soc.1993,115,9907-9919.(c)Bra ¨uner-Osborne,H.;Egebjerg,J.;Nielsen,E.;Madsen,U.;Krogsgaard-Larsen,P.J.Med.Chem.2000,43,2609-2645.(d)Zacharias,N.;Dougherty,D.A.Trends Pharmacol.Sci.2002,23,281-287.(e)Hu,J.;Barbour,L.J.;Gokel,G.W.J.Am.Chem.Soc.2002,124,10940-10941.Chart 1.Some Receptors Employed for Dicarboxylic Acid and N -AcetylglutamateRecognitionChart 2.New 1H -Pyrazole-Containing Polyamine Receptors Able To Complex L -Glutamate inWaterA R T I C L E SMiranda et al.824J.AM.CHEM.SOC.9VOL.126,NO.3,2004strengths.1[L1]and2[L2]differ in the N-benzylation of the pyrazole moiety,and1[L1]and3[L3]differ in the presence in the center of the polyamine side chains of an amino group or of a methylene group.The receptors4[L4]and5[L5]present the central nitrogens of the chain N-functionalized with benzyl or phenethyl groups,and6[L6]has large hydrophobic octyl groups.Results and DiscussionSynthesis of3-6.Macrocycles3-6have been obtained following the procedure previously reported for the preparation of1and2.23The method includes a first dipodal(2+2) condensation of the1H-pyrazol-3,5-dicarbaldehyde7with the corresponding R,ω-diamine,followed by hydrogenation of the resulting Schiff base imine bonds.In the case of receptor3,the Schiff base formed by condensation with1,5-pentanediamine is a stable solid(8,mp208-210°C)which precipitated in68% yield from the reaction mixture.Further reduction with NaBH4 in absolute ethanol gave the expected tetraazamacrocycle3, which after crystallization from toluene was isolated as a pure compound(mp184-186°C).In the cases of receptors4-6, the precursor R,ω-diamines(11a-11c)(Scheme1B)were obtained,by using a procedure previously described for11a.24 This procedure is based on the previous protection of the primary amino groups of1,5-diamino-3-azapentane by treatment with phthalic anhydride,followed by alkylation of the secondary amino group of1,5-diphthalimido-3-azapentane9with benzyl, phenethyl,or octyl bromide.Finally,the phthalimido groups of the N-alkyl substituted intermediates10a-10c were removed by treatment with hydrazine to afford the desired amines11a-11c,which were obtained in moderate yield(54-63%).In contrast with the behavior previously observed in the synthesis of3,in the(2+2)dipodal condensations of7with 3-benzyl-,3-phenethyl-,and3-octyl-substituted3-aza-1,5-pentanediamine11a,11b,and11c,respectively,there was not precipitation of the expected Schiff bases(Scheme1A). Consequently,the reaction mixtures were directly reduced in situ with NaBH4to obtain the desired hexaamines4-6,which after being carefully purified by chromatography afforded purecolorless oils in51%,63%,and31%yield,respectively.The structures of all of these new cyclic polyamines have been established from the analytical and spectroscopic data(MS(ES+), 1H and13C NMR)of both the free ligands3-6and their corresponding hydrochloride salts[3‚4HCl,4‚6HCl,5‚6HCl, and6‚6HCl],which were obtained as stable solids following the same procedure previously reported18for1‚6HCl and2‚6HCl.As usually occurs for3,5-disubstituted1H-pyrazole deriva-tives,either the free ligands3-6or their hydrochlorides show very simple1H and13C NMR spectra,in which signals indicate that,because of the prototropic equilibrium of the pyrazole ring, all of these compounds present average4-fold symmetry on the NMR scale.The quaternary C3and C5carbons appear together,and the pairs of methylene carbons C6,C7,and C8are magnetically equivalent(see Experimental Section).In the13C NMR spectra registered in CDCl3solution, significant differences can be observed between ligand3,without an amino group in the center of the side chain,and the N-substituted ligands4-6.In3,the C3,5signal appears as a broad singlet.However,in4-6,it almost disappears within the baseline of the spectra,and the methylene carbon atoms C6and C8experience a significant broadening.Additionally,a remark-able line-broadening is also observed in the C1′carbon signals belonging to the phenethyl and octyl groups of L5and L6, respectively.All of these data suggest that as the N-substituents located in the middle of the side chains of4-6are larger,the dynamic exchange rate of the pyrazole prototropic equilibrium is gradually lower,probably due to a relation between proto-tropic and conformational equilibria.Acid-Base Behavior.To follow the complexation of L-glutamate(hereafter abbreviated as Glu2-)and its protonated forms(HGlu-,H2Glu,and H3Glu+)by the receptors L1-L6, the acid-base behavior of L-glutamate has to be revisited under the experimental conditions of this work,298K and0.15mol dm-3.The protonation constants obtained,included in the first column of Table1,agree with the literature25and show that the zwitterionic HGlu-species is the only species present in aqueous solution at physiological pH values(Scheme2and Figure S1of Supporting Information).Therefore,receptors for(23)Ara´n,V.J.;Kumar,M.;Molina,J.;Lamarque,L.;Navarro,P.;Garcı´a-Espan˜a,E.;Ramı´rez,J.A.;Luis,S.V.;Escuder,.Chem.1999, 64,6137-6146.(24)(a)Yuen Ng,C.;Motekaitis,R.J.;Martell,A.E.Inorg.Chem.1979,18,2982-2986.(b)Anelli,P.L.;Lunazzi,L.;Montanari,F.;Quici,.Chem.1984,49,4197-4203.Scheme1.Synthesis of the Pyrazole-Containing MacrocyclicReceptorsNew1H-Pyrazole-Containing Polyamine Receptors A R T I C L E SJ.AM.CHEM.SOC.9VOL.126,NO.3,2004825glutamate recognition able to address both the negative charges of the carboxylate groups and the positive charge of ammonium are highly relevant.The protonation constants of L 3-L 6are included in Table 1,together with those we have previously reported for receptors L 1and L 2.23A comparison of the constants of L 4-L 6with those of the nonfunctionalized receptor L 1shows a reduced basicity of the receptors L 4-L 6with tertiary nitrogens at the middle of the polyamine bridges.Such a reduction in basicity prevented the potentiometric detection of the last protonation for these ligands in aqueous solution.A similar reduction in basicity was previously reported for the macrocycle with the N -benzylated pyrazole spacers (L 2).23These diminished basicities are related to the lower probability of the tertiary nitrogens for stabilizing the positive charges through hydrogen bond formation either with adjacent nonprotonated amino groups of the molecule or with water molecules.Also,the increase in the hydrophobicity of these molecules will contribute to their lower basicity.The stepwise basicity constants are relatively high for the first four protonation steps,which is attributable to the fact that these protons can bind to the nitrogen atoms adjacent to the pyrazole groups leaving the central nitrogen free,the electrostatic repulsions between them being therefore of little significance.The remaining protonation steps will occur in the central nitrogen atom,which will produce an important increase in the electrostatic repulsion in the molecule and therefore a reduction in basicity.As stated above,the tertiary nitrogen atoms present in L 4-L 6will also contribute to this diminished basicity.To analyze the interaction with glutamic acid,it is important to know the protonation degree of the ligands at physiological pH values.In Table 2,we have calculated the percentages ofthe different protonated species existing in solution at pH 7.4for receptors L 1-L 6.As can be seen,except for the receptor with the pentamethylenic chains L 3in which the tetraprotonated species prevails,all of the other systems show that the di-and triprotonated species prevail,although to different extents.Interaction with Glutamate.The stepwise constants for the interaction of the receptors L 1-L 6with glutamate are shown in Table 3,and selected distribution diagrams are plotted in Figure 1A -C.All of the studied receptors interact with glutamate forming adduct species with protonation degrees (j )which vary between 8and 0depending on the system (see Table 3).The stepwise constants have been derived from the overall association constants (L +Glu 2-+j H +)H j LGlu (j -2)+,log j )provided by the fitting of the pH-metric titration curves.This takes into account the basicities of the receptors and glutamate (vide supra)and the pH range in which a given species prevails in solution.In this respect,except below pH ca.4and above pH 9,HGlu -can be chosen as the protonated form of glutamate involved in the formation of the different adducts.Below pH 4,the participation of H 2Glu in the equilibria has also to be considered (entries 9and 10in Table 3).For instance,the formation of the H 6LGlu 4+species can proceed through the equilibria HGlu -+H 5L 5+)H 6LGlu 4+(entry 8,Table 3),and H 2Glu +H 4L 4+)H 6LGlu 4(entry 9Table 3),with percentages of participation that depend on pH.One of the effects of the interaction is to render somewhat more basic the receptor,and somewhat more acidic glutamic acid,facilitating the attraction between op-positely charged partners.A first inspection of Table 3and of the diagrams A,B,and C in Figure 1shows that the interaction strengths differ markedly from one system to another depending on the structural features of the receptors involved.L 4is the receptor that presents the highest capacity for interacting with glutamate throughout all of the pH range explored.It must also be remarked that there are not clear-cut trends in the values of the stepwise constants as a function of the protonation degree of the receptors.This suggests that charge -charge attractions do not play the most(25)(a)Martell,E.;Smith,R.M.Critical Stability Constants ;Plenum:NewYork,1975.(b)Motekaitis,R.J.NIST Critically Selected Stability Constants of Metal Complexes Database ;NIST Standard Reference Database,version 4,1997.Table 1.Protonation Constants of Glutamic Acid and Receptors L 1-L 6Determined in NaCl 0.15mol dm -3at 298.1KreactionGluL 1aL 2aL 3bL 4L 5L 6L +H )L H c 9.574(2)d 9.74(2)8.90(3)9.56(1)9.25(3)9.49(4)9.34(5)L H +H )L H 2 4.165(3)8.86(2)8.27(2)8.939(7)8.38(3)8.11(5)8.13(5)L H 2+H )L H 3 2.18(2)7.96(2) 6.62(3)8.02(1) 6.89(5)7.17(6)7.46(7)L H 3+H )L H 4 6.83(2) 5.85(4)7.63(1) 6.32(5) 6.35(6) 5.97(8)L H 4+H )L H 5 4.57(3) 3.37(4) 2.72(8) 2.84(9) 3.23(9)L H 5+H )L H 6 3.18(3) 2.27(6)∑log K H n L41.135.334.233.634.034.1aTaken from ref 23.b These data were previously cited in a short communication (ref 26).c Charges omitted for clarity.d Values in parentheses are the standard deviations in the last significant figure.Scheme 2.L -Glutamate Acid -BaseBehaviorTable 2.Percentages of the Different Protonated Species at pH 7.4H 1L aH 2LH 3LH 4LL 11186417L 21077130L 3083458L 4083458L 51154323L 6842482aCharges omitted for clarity.A R T I C L E SMiranda et al.826J.AM.CHEM.SOC.9VOL.126,NO.3,2004outstanding role and that other forces contribute very importantly to these processes.26However,in systems such as these,which present overlapping equilibria,it is convenient to use conditional constants because they provide a clearer picture of the selectivity trends.27These constants are defined as the quotient between the overall amounts of complexed species and those of free receptor and substrate at a given pH[eq1].In Figure2are presented the logarithms of the effective constants versus pH for all of the studied systems.Receptors L1and L2with a nonfunctionalized secondary amino group in the side chains display opposite trend from all other receptors. While the stability of the L1and L2adducts tends to increase with pH,the other ligands show a decreasing interaction. Additionally,L1and L2present a close interaction over the entire pH range under study.The tetraaminic macrocycle L3is a better(26)Escartı´,F.;Miranda,C.;Lamarque,L.;Latorre,J.;Garcı´a-Espan˜a,E.;Kumar,M.;Ara´n,V.J.;Navarro,mun.2002,9,936-937.(27)(a)Bianchi,A.;Garcı´a-Espan˜a,c.1999,12,1725-1732.(b)Aguilar,J.A.;Celda,B.;Garcı´a-Espan˜a,E.;Luis,S.V.;Martı´nez,M.;Ramı´rez,J.A.;Soriano,C.;Tejero,B.J.Chem.Soc.,Perkin Trans.22000, 7,1323-1328.Table3.Stability Constants for the Interaction of L1-L6with the Different Protonated Forms of Glutamate(Glu) entry reaction a L1L2L3L4L5L6 1Glu+L)Glu L 3.30(2)b 4.11(1)2HGlu+L)HGlu L 3.65(2) 4.11(1) 3.68(2) 3.38(4) 3Glu+H L)HGlu L 3.89(2) 4.48(1) 3.96(2) 3.57(4) 4HGlu+H L)H2Glu L 3.49(2) 3.89(1) 2.37(4) 3.71(2)5HGlu+H2L)H3Glu L 3.44(2) 3.73(1) 2.34(3) 4.14(2) 2.46(4) 2.61(7) 6HGlu+H3L)H4Glu L 3.33(2) 3.56(2) 2.66(3) 4.65(2) 2.74(3) 2.55(7) 7HGlu+H4L)H5Glu L 3.02(2) 3.26(2) 2.58(3) 4.77(2) 2.87(3) 2.91(5) 8HGlu+H5L)H6Glu L 3.11(3) 3.54(2) 6.76(3) 4.96(3) 4.47(3) 9H2Glu+H4L)H6Glu L 2.54(3) 3.05(2) 3.88(2) 5.35(3) 3.66(4) 3.56(3) 10H2Glu+H5L)H7Glu L 2.61(6) 2.73(4) 5.51(3) 3.57(4) 3.22(8) 11H3Glu+H4L)H7Glu L 4.82(2) 4.12(9)a Charges omitted for clarity.b Values in parentheses are standard deviations in the last significantfigure.Figure1.Distribution diagrams for the systems(A)L1-glutamic acid, (B)L4-glutamic acid,and(C)L5-glutamicacid.Figure2.Representation of the variation of K cond(M-1)for the interaction of glutamic acid with(A)L1and L3,(B)L2,L4,L5,and L6.Initial concentrations of glutamate and receptors are10-3mol dm-3.Kcond)∑[(H i L)‚(H j Glu)]/{∑[H i L]∑[H j Glu]}(1)New1H-Pyrazole-Containing Polyamine Receptors A R T I C L E SJ.AM.CHEM.SOC.9VOL.126,NO.3,2004827receptor at acidic pH,but its interaction markedly decreases on raising the pH.These results strongly suggest the implication of the central nitrogens of the lateral polyamine chains in the stabilization of the adducts.Among the N-functionalized receptors,L4presents the largest interaction with glutamate.Interestingly enough,L5,which differs from L4only in having a phenethyl group instead of a benzyl one,presents much lower stability of its adducts.Since the basicity and thereby the protonation states that L4and L5 present with pH are very close,the reason for the larger stability of the L4adducts could reside on a better spatial disposition for formingπ-cation interactions with the ammonium group of the amino acid.In addition,as already pointed out,L4presents the highest affinity for glutamic acid in a wide pH range,being overcome only by L1and L2at pH values over9.This observation again supports the contribution ofπ-cation inter-actions in the system L4-glutamic because at these pH values the ammonium functionality will start to deprotonate(see Scheme2and Figure1B).Table4gathers the percentages of the species existing in equilibria at pH7.4together with the values of the conditional constant at this pH.In correspondence with Figure1A,1C and Figure S2(Supporting Information),it can be seen that for L1, L2,L5,and L6the prevailing species are[H2L‚HGlu]+and[H3L‚HGlu]2+(protonation degrees3and4,respectively),while for L3the main species are[H3L‚HGlu]+and[H4L‚HGlu]2+ (protonation degrees4and5,respectively).The most effective receptor at this pH would be L4which joins hydrogen bonding, charge-charge,andπ-cation contributions for the stabilization of the adducts.To check the selectivity of this receptor,we have also studied its interaction with L-aspartate,which is a competitor of L-glutamate in the biologic receptors.The conditional constant at pH7.4has a value of3.1logarithmic units for the system Asp-L4.Therefore,the selectivity of L4 for glutamate over aspartate(K cond(L4-glu)/K cond(L4-asp))will be of ca.15.It is interesting to remark that the affinity of L4 for zwiterionic L-glutamate at pH7.4is even larger than that displayed by receptors III and IV(Chart1)with the protected dianion N-acetyl-L-glutamate lacking the zwitterionic charac-teristics.Applying eq1and the stability constants reported in ref17,conditional constants at pH7.4of 3.24and 2.96 logarithmic units can be derived for the systems III-L-Glu and IV-L-Glu,respectively.Molecular Modeling Studies.Molecular mechanics-based methods involving docking studies have been used to study the binding orientations and affinities for the complexation of glutamate by L1-L6receptors.The quality of a computer simulation depends on two factors:accuracy of the force field that describes intra-and intermolecular interactions,and an adequate sampling of the conformational and configuration space of the system.28The additive AMBER force field is appropriate for describing the complexation processes of our compounds,as it is one of the best methods29in reproducing H-bonding and stacking stabiliza-tion energies.The experimental data show that at pH7.4,L1-L6exist in different protonation states.So,a theoretical study of the protonation of these ligands was done,including all of the species shown in5%or more abundance in the potentiometric measurements(Table4).In each case,the more favored positions of protons were calculated for mono-,di-,tri-,and tetraprotonated species.Molecular dynamics studies were performed to find the minimum energy conformations with simulated solvent effects.Molecular modeling studies were carried out using the AMBER30method implemented in the Hyperchem6.0pack-age,31modified by the inclusion of appropriate parameters. Where available,the parameters came from analogous ones used in the literature.32All others were developed following Koll-man33and Hopfinger34procedures.The equilibrium bond length and angle values came from experimental values of reasonable reference compounds.All of the compounds were constructed using standard geometry and standard bond lengths.To develop suitable parameters for NH‚‚‚N hydrogen bonding,ab initio calculations at the STO-3G level35were used to calculate atomic charges compatible with the AMBER force field charges,as they gave excellent results,and,at the same time,this method allows the study of aryl-amine interactions.In all cases,full geometry optimizations with the Polak-Ribiere algorithm were carried out,with no restraints.Ions are separated far away and well solvated in water due to the fact that water has a high dielectric constant and hydrogen bond network.Consequently,there is no need to use counteri-ons36in the modelization studies.In the absence of explicit solvent molecules,a distance-dependent dielectric factor quali-tatively simulates the presence of water,as it takes into account the fact that the intermolecular electrostatic interactions should vanish more rapidly with distance than in the gas phase.The same results can be obtained using a constant dielectric factor greater than1.We have chosen to use a distance-dependent dielectric constant( )4R ij)as this was the method used by Weiner et al.37to develop the AMBER force field.Table8 shows the theoretical differences in protonation energy(∆E p) of mono-,bi-,and triprotonated hexaamine ligands,for the (28)Urban,J.J.;Cronin,C.W.;Roberts,R.R.;Famini,G.R.J.Am.Chem.Soc.1997,119,12292-12299.(29)Hobza,P.;Kabelac,M.;Sponer,J.;Mejzlik,P.;Vondrasek,put.Chem.1997,18,1136-1150.(30)Cornell,W.D.;Cieplak,P.;Bayly,C.I.;Gould,I.R.;Merz,K.M.,Jr.;Ferguson,D.M.;Spelmeyer,D.C.;Fox,T.;Caldwell,J.W.;Kollman,P.A.J.Am.Chem.Soc.1995,117,5179-5197.(31)Hyperchem6.0(Hypercube Inc.).(32)(a)Fox,T.;Scanlan,T.S.;Kollman,P.A.J.Am.Chem.Soc.1997,119,11571-11577.(b)Grootenhuis,P.D.;Kollman,P.A.J.Am.Chem.Soc.1989,111,2152-2158.(c)Moyna,G.;Hernandez,G.;Williams,H.J.;Nachman,R.J.;Scott,put.Sci.1997,37,951-956.(d)Boden,C.D.J.;Patenden,put.-Aided Mol.Des.1999, 13,153-166.(33)/amber.(34)Hopfinger,A.J.;Pearlstein,put.Chem.1984,5,486-499.(35)Glennon,T.M.;Zheng,Y.-J.;Le Grand,S.M.;Shutzberg,B.A.;Merz,K.M.,put.Chem.1994,15,1019-1040.(36)Wang,J.;Kollman,P.A.J.Am.Chem.Soc.1998,120,11106-11114.Table4.Percentages of the Different Protonated Adducts[HGlu‚H j L](j-1)+,Overall Percentages of Complexation,andConditional Constants(K Cond)at pH7.4for the Interaction ofGlutamate(HGlu-)with Receptors L1-L6at Physiological pH[H n L‚HGlu]an)1n)2n)3n)4∑{[H n L‚HGlu]}K cond(M-1)L13272353 2.44×103L2947763 4.12×103L31101324 3.99×102L423737581 2.04×104L51010222 3.51×102L6121224 3.64×102a Charges omitted for clarity.A R T I C L E S Miranda et al. 828J.AM.CHEM.SOC.9VOL.126,NO.3,2004。

CHAPTER1INTRODUCTION1.1What is thermodynamics?Thermodynamics is the science which has evolved from the original investiga-tions in the19th century into the nature of“heat.”At the time,the leading theory of heat was that it was a type offluid,which couldflow from a hot body to a colder one when they were brought into contact.We now know that what was then called“heat”is not afluid,but is actually a form of energy–it is the energy associated with the continual,random motion of the atoms which compose macroscopic matter,which we can’t see directly.This type of energy,which we will call thermal energy,can be converted (at least in part)to other forms which we can perceive directly(for example, kinetic,gravitational,or electrical energy),and which can be used to do useful things such as propel an automobile or a747.The principles of thermodynamics govern the conversion of thermal energy to other,more useful forms.For example,an automobile engine can be though of as a device whichfirst converts chemical energy stored in fuel and oxygen molecules into thermal en-ergy by combustion,and then extracts part of that thermal energy to perform the work necessary to propel the car forward,overcoming friction.Thermody-namics is critical to all steps in this process(including determining the level of pollutants emitted),and a careful thermodynamic analysis is required for the design of fuel-efficient,low-polluting automobile engines.In general,thermody-namics plays a vital role in the design of any engine or power-generating plant, and therefore a good grounding in thermodynamics is required for much work in engineering.If thermodynamics only governed the behavior of engines,it would probably be the most economically important of all sciences,but it is much more than that.Since the chemical and physical state of matter depends strongly on how much thermal energy it contains,thermodynamic principles play a central role in any description of the properties of matter.For example,thermodynamics allows us to understand why matter appears in different phases(solid,liquid, or gaseous),and under what conditions one phase will transform to another.1CHAPTER1.INTRODUCTION2The composition of a chemically-reacting mixture which is given enough time to come to“equilibrium”is also fully determined by thermodynamic principles (even though thermodynamics alone can’t tell us how fast it will get there).For these reasons,thermodynamics lies at the heart of materials science,chemistry, and biology.Thermodynamics in its original form(now known as classical thermodynam-ics)is a theory which is based on a set of postulates about how macroscopic matter behaves.This theory was developed in the19th century,before the atomic nature of matter was accepted,and it makes no reference to atoms.The postulates(the most important of which are energy conservation and the impos-sibility of complete conversion of heat to useful work)can’t be derived within the context of classical,macroscopic physics,but if one accepts them,a very powerful theory results,with predictions fully in agreement with experiment.When at the end of the19th century itfinally became clear that matter was composed of atoms,the physicist Ludwig Boltzmann showed that the postu-lates of classical thermodynamics emerged naturally from consideration of the microscopic atomic motion.The key was to give up trying to track the atoms in-dividually and instead take a statistical,probabilistic approach,averaging over the behavior of a large number of atoms.Thus,the very successful postulates of classical thermodynamics were given afirm physical foundation.The science of statistical mechanics begun by Boltzmann encompasses everything in classical thermodynamics,but can do more also.When combined with quantum me-chanics in the20th century,it became possible to explain essentially all observed properties of macroscopic matter in terms of atomic-level physics,including es-oteric states of matter found in neutron stars,superfluids,superconductors,etc. Statistical physics is also currently making important contributions in biology, for example helping to unravel some of the complexities of how proteins fold.Even though statistical mechanics(or statistical thermodynamics)is in a sense“more fundamental”than classical thermodynamics,to analyze practical problems we usually take the macroscopic approach.For example,to carry out a thermodynamic analysis of an aircraft engine,its more convenient to think of the gas passing through the engine as a continuumfluid with some specified properties rather than to consider it to be a collection of molecules.But we do use statistical thermodynamics even here to calculate what the appropriate property values(such as the heat capacity)of the gas should be.CHAPTER1.INTRODUCTION3 1.2Energy and EntropyThe two central concepts of thermodynamics are energy and entropy.Most other concepts we use in thermodynamics,for example temperature and pres-sure,may actually be defined in terms of energy and entropy.Both energy and entropy are properties of physical systems,but they have very different characteristics.Energy is conserved:it can neither be produced nor destroyed, although it is possible to change its form or move it around.Entropy has a different character:it can’t be destroyed,but it’s easy to produce more entropy (and almost everything that happens actually does).Like energy,entropy too can appear in different forms and be moved around.A clear understanding of these two properties and the transformations they undergo in physical processes is the key to mastering thermodynamics and learn-ing to use it confidently to solve practical problems.Much of this book is focused on developing a clear picture of energy and entropy,explaining their origins in the microscopic behavior of matter,and developing effective methods to analyze complicated practical processes1by carefully tracking what happens to energy and entropy.1.3Some TerminologyMostfields have their own specialized terminology,and thermodynamics is cer-tainly no exception.A few important terms are introduced here,so we can begin using them in the next chapter.1.3.1System and EnvironmentIn thermodynamics,like in most other areas of physics,we focus attention on only a small part of the world at a time.We call whatever object(s)or region(s) of space we are studying the system.Everything else surrounding the system (in principle including the entire universe)is the environment.The boundary between the system and the environment is,logically,the system boundary. The starting point of any thermodynamic analysis is a careful definition of the system.EnvironmentSystemBoundarySystemCHAPTER 1.INTRODUCTION4Figure 1.1:Control masses and control volumes.1.3.2Open,closed,and isolated systemsAny system can be classified as one of three types:open,closed,or isolated.They are defined as follows:open system:Both energy and matter can be exchanged with the environ-ment.Example:an open cup of coffee.closed system:energy,but not matter,can be exchanged with the environ-ment.Examples:a tightly capped cup of coffee.isolated system:Neither energy nor matter can be exchanged with the envi-ronment –in fact,no interactions with the environment are possible at all.Example (approximate):coffee in a closed,well-insulated thermos bottle.Note that no system can truly be isolated from the environment,since no thermal insulation is perfect and there are always physical phenomena which can’t be perfectly excluded (gravitational fields,cosmic rays,neutrinos,etc.).But good approximations of isolated systems can be constructed.In any case,isolated systems are a useful conceptual device,since the energy and mass con-tained inside them stay constant.1.3.3Control masses and control volumesAnother way to classify systems is as either a control mass or a control volume .This terminology is particularly common in engineering thermodynamics.A control mass is a system which is defined to consist of a specified piece or pieces of matter.By definition,no matter can enter or leave a control mass.If the matter of the control mass is moving,then the system boundary moves with it to keep it inside (and matter in the environment outside).A control volume is a system which is defined to be a particular region of space.Matter and energy may freely enter or leave a control volume,and thus it is an open system.CHAPTER1.INTRODUCTION5 1.4A Note on UnitsIn this book,the SI system of units will be used exclusively.If you grew up anywhere but the United States,you are undoubtedly very familiar with this system.Even if you grew up in the US,you have undoubtedly used the SI system in your courses in physics and chemistry,and probably in many of your courses in engineering.One reason the SI system is convenient is its simplicity.Energy,no matter what its form,is measured in Joules(1J=1kg-m2/s2).In some other systems, different units are used for thermal and mechanical energy:in the English sys-tem a BTU(“British Thermal Unit”)is the unit of thermal energy and a ft-lbf is the unit of mechanical energy.In the cgs system,thermal energy is measured in calories,all other energy in ergs.The reason for this is that these units were chosen before it was understood that thermal energy was like mechanical energy, only on a much smaller scale.2Another advantage of SI is that the unit of force is indentical to the unit of(mass x acceleration).This is only an obvious choice if one knows about Newton’s second law,and allows it to be written asF=m a.(1.1)In the SI system,force is measured in kg-m/s2,a unit derived from the3primary SI quantities for mass,length,and time(kg,m,s),but given the shorthand name of a“Newton.”The name itself reveals the basis for this choice of force units.The units of the English system werefixed long before Newton appeared on the scene(and indeed were the units Newton himself would have used).The unit of force is the“pound force”(lbf),the unit of mass is the“pound mass”(lbm)and of course acceleration is measured in ft/s2.So Newton’s second law must include a dimensional constant which converts from Ma units(lbm ft/s2) to force units(lbf).It is usually written1F=2Mixed unit systems are sometimes used too.American power plant engineers speak of the “heat rate”of a power plant,which is defined as the thermal energy which must be absorbed from the furnace to produce a unit of electrical energy.The heat rate is usually expressed in BTU/kw-hr.CHAPTER1.INTRODUCTION6In practice,the units in the English system are now defined in terms of their SI equivalents(e.g.one foot is defined as a certain fraction of a meter,and one lbf is defined in terms of a Newton.)If given data in Engineering units,it is often easiest to simply convert to SI,solve the problem,and then if necessary convert the answer back at the end.For this reason,we will implicitly assume SI units in this book,and will not include the g c factor in Newton’s2nd law.。