SwRI - LUBRICANT EFFECTS ON LUBRICANT EFFECTS ON AFTERTREATMENT CATALYSTS

2020年12月Dec.2020润滑油LUBRICATING OIL第35卷第6期V ol.35,N o.6D O I：10.19532/j. cnki. cn21 -1265/tq. 2020.06.009 文章编号:1002-3119(2020)06-0043-09碳纳米材料在润滑油脂中的应用开发彭春明，张玉娟，张晟卯，杨广彬，宋宁宁,张平余(河南大学纳米材料T程研究中心，河南开封475001 )摘要:纳米材料因在润滑油脂中展现出优越的摩擦学性能引起人们极大的兴趣。

碳纳米材料因其多样且独特的形态和微观结 构，具有物理化学性能独特、热稳定性强和剪切强度低等特点，作为润滑油脂添加剂在高温、长效、环保要求高的润滑环境中具 有不可替代的优势。

文章从碳纳米材料的结构、表面改性、与其他润滑材料复合等方面综述了碳纳米材料作为添加剂在润滑 油脂领域中的性能和机制研究及其应用开发。

关键词:碳纳米材料;添加剂;综述中图分类号:TE624.82 文献标识码:AApplication and Development of Carbon Nanomaterials in Lubricating Oil and GreasePENG Chun - ming, ZHANG Yu - juan, ZHANG Sheng - mao, YANG Guang - bin,SONG Ning-ning，ZHANG Ping-yu(Engineering Research Center for Nanomaterials of He^nan University, Kaifeng 475001, China)Abstract ：Nanomaterials are of great interest because of their excellent tribological properties in lubricating oil and grease. Carbon nanomaterials have unique physical and chemical properties, strong thermal stability and low shear strength due to their diverse and unique morphology and microstructure. As lubricant additives, they have irreplaceable advantages in high temperature, long - term and high environmental protection requirements. In this paper, the properties, mechanism and ap­plication of carbon nanomaterials as additives in the field of lubricating oil and grease are reviewed from the aspects of struc­ture, surface modification and composite with other lubricating materials.Key words：carbon nanomaterials；additive；review〇引言摩擦磨损是机械运转过程中能量和材料损耗的 主要原因。

Journal of Chromatography A,1081(2005)145–155Residue determination of glyphosate,glufosinate and aminomethylphosphonic acid in water and soil samples by liquidchromatography coupled to electrospray tandem mass spectrometryMar´ıa Ib´a˜n ez,´Oscar J.Pozo,Juan V.Sancho,Francisco J.L´o pez,F´e lix Hern´a ndez∗Research Institute for Pesticides and Water,University Jaume I,E-12071Castell´o n,SpainReceived11February2005;received in revised form3May2005;accepted17May2005AbstractThis paper describes a method for the sensitive and selective determination of glyphosate,glufosinate and aminomethylphosphonic acid (AMPA)residues in water and soil samples.The method involves a derivatization step with9-fluorenylmethylchloroformate(FMOC)in borate buffer and detection based on liquid chromatography coupled to electrospray tandem mass spectrometry(LC–ESI-MS/MS).In the case of water samples a volume of10mL was derivatized and then4.3mL of the derivatized mixture was directly injected in an on-line solid phase extraction(SPE)–LC–MS/MS system using an OASIS HLB cartridge column and a Discovery chromatographic column.Soil samples were firstly extracted with potassium hydroxide.After that,the aqueous extract was10-fold diluted with water and2mL were derivatized.Then, 50␮L of the derivatized10-fold diluted extract were injected into the LC–MS/MS system without pre-concentration into the SPE cartridge. The method has been validated in both ground and surface water by recovery studies with samples spiked at50and500ng/L,and also in soil samples,spiked at0.05and0.5mg/kg.In water samples,the mean recovery values ranged from89to106%for glyphosate(RSD<9%),from 97to116%for AMPA(RSD<10%),and from72to88%in the case of glufosinate(RSD<12%).Regarding soil samples,the mean recovery values ranged from90to92%for glyphosate(RSD<7%),from88to89%for AMPA(RSD<5%)and from83to86%for glufosinate (RSD<6%).Limits of quantification for all the three compounds were50ng/L and0.05mg/kg in water and soil,respectively,with limits of detection as low as5ng/L,in water,and5␮g/kg,in soil.The use of labelled glyphosate as internal standard allowed improving the recovery and precision for glyphosate and AMPA,while it was not efficient for glufosinate,that was quantified by external standards calibration.The method developed has been applied to the determination of these compounds in real water and soil samples from different areas.All the detections were confirmed by acquiring two transitions for each compound.©2005Elsevier B.V.All rights reserved.Keywords:Glyphosate;Glufosinate;AMPA;Water;Soil;Liquid chromatography;Electrospray interface;Tandem mass spectrometry;Derivatization1.IntroductionGlyphosate[N-(phosphonomethyl)glycine]and glufos-inate[ammonium dl-homoalanin-4-(methyl)phosphinate] are broad spectrum,nonselective,post-emergence herbicides extensively used in various applications for weed control in aquatic systems and vegetation control in non-crop areas. Aminomethylphosphonic acid(AMPA)is the major degra-dation product of glyphosate found in plants,water and soil ∗Corresponding author.Tel.:+34964728100;fax:+34964728066.E-mail address:hernandf@exp.uji.es(F.Hern´a ndez).[1].Chemical structures of these phosphorus-containing her-bicides are given in Fig.1.Due to the extensive worldwide use of these compounds and the restrictive regulations for water in the European Union,very sensitive methods for the determination of pes-ticide residues are required.However,the determination of these two herbicides at the sub␮g/L level is difficult due to their ionic character,low volatility,low mass and lack of chemical groups that could facilitate their detection.Even more difficult can result the residue determination in soil at low concentration levels(e.g.below0.1mg/kg),due to the complexity of this matrix sample.Most methods developed0021-9673/$–see front matter©2005Elsevier B.V.All rights reserved. doi:10.1016/j.chroma.2005.05.041146M.Ib´a ˜n ez et al./J.Chromatogr.A 1081(2005)145–155Fig.1.Chemical structures of glyphosate,AMPA and glufosinate,and derivatization reaction with FMOC.R:H or alkyl group.until now require derivatization procedures to enable analy-sis by gas chromatography (GC)or high-performance liquidchromatography (HPLC).GC/MS methods involved deriva-tization with different reagents [2–8]to confer volatility to the analytes.Normally,there is quite a lot of sample manip-ulation,and the methods are time-consuming and tedious.Physicochemical characteristics of these compounds fit better with LC analysis,although the lack of adequate chem-ical groups (e.g.chromophores,UV absorption,fluorogenics)hamper their measurement by conventional detectors.For these reasons,both pre-column and post-column derivatiza-tion procedures have been employed.Pre-column procedures are based mainly on derivatization with 9-fluorenylmethyl chloroformate (FMOC)[9–15]to form fluorescent deriva-tives (improve detection)and/or to reduce the polar character of the analytes facilitating the chromatographic retention.In post-column procedures,the most common reaction is with o-phthalaldehyde (OPA)and mercaptoethanol [16]or with OPA and N ,N -dimethyl-2-mercaptoethylamine [17].Nor-mally,HPLC has been used in combination with fluorescence detection after derivatization [11–17],although in a few cases glyphosate has been determined directly by ion chromatogra-phy (IC)with UV detection [18]or suppressed conductivity detection [19],but with limited sensitivity.The potential of capillary electrophoresis combined with mass spectrometry [20]and with indirect fluorescence detection [21]has also been explored,although the lack of sensitivity and/or selec-tivity of these techniques together with the difficulty for preconcentrating the analytes,limited their application in the field of residues.In our research group,we have developed efficient and selective methods based on the use of coupled-column liquid chromatography (LC–LC),which was proved to be an excel-lent way of minimizing sample treatment and improving sen-sitivity in a variety of sample matrices,as water,soil,fruit and vegetables [11,13–15,22].However,the use of conventional fluorescent detection limited the sensitivity required in pesti-cide residue analysis,and also hampered the unequivocal con-firmation of the residues detected,which nowadays is widely accepted that has to be reached by MS techniques.Searching a method that could satisfy the requirements of sensitivity and selectivity,and unequivocal confirmation of glyphosate in water,the use of MS spectrometric techniques in combina-tion with LC has been investigated by several groups.Thus,IC has been applied,due the ionic character of this analyte,coupled to MS with electrospray interface [23],while RPLC has been used in combination with ICP-MS with P detection [24].However,the sensitivity reached with these techniques was not sufficient.Lee et al [9]obtained better results with the combination LC–MS.In this case,the molecular ions of the derivatized glyphosate,AMPA and glufosinate,as well as a fragment ion of each compound,were monitored in negative ionisation mode obtaining detection limits around 0.1␮g/L.The use of isotope-labelled glyphosate as inter-nal standard minimised derivatization variations and matrix effects.However,although MS based methods could be con-sidered as highly selective methods,the occurrence of false positives might be still possible mainly in the analysis of rel-atively dirty samples,as some interferences can share the same MS properties as the analyte.This may also occur in water sample analysis as it has been reported in some papers,producing constructive discussions on this subject [25].The improved sensitivity and selectivity of tandem MS make this technique ideal for the trace level determination of polar and/or ionic pesticides in water by LC–MS/MS meth-ods,as it has been proved in our laboratory [26–27].This tech-nique was also applied several years ago to the determination of glyphosate and AMPA in water [10],although considerable variation was observed caused by irreproducibility in deriva-tization and fragmentation.4-mL volume was passed through the SPE cartridge,claiming detection limits for glyphosate and AMPA around 0.03␮g/L.When dealing with more complex matrices,such as soil samples,an important loss in the sensitivity can occur a con-sequence of the ionisation suppression from the co-extracted components of the matrix,hampering correct quantification.This matrix-effect depends on the analyte-sample combina-tion.Different approaches have been used either to minimize or to correct the matrix effect,such as increasing the sample pretreatment,performing matrix-matched calibration,using an isotope labelled standard or simply diluting the sample [28].Thus,the labeled glyphosate has been used as internal standard for the LC–MS determination of this herbicide [9].Confirmation of the identity of residues in unknown sam-ples is of utmost importance in order to avoid reporting falseM.Ib´a˜n ez et al./J.Chromatogr.A1081(2005)145–155147positives.Recently,the European Union has adopted the con-cept of identification points(IPs)as quality criterium for the confirmation of contaminant residues[29].For compounds with an established MRL,a minimum of three IPs is required for satisfactory confirmation of the compound identity.When LC–MS/MS technique is used,the monitoring of two MS/MS transitions,ing one precursor ion and two product ions, allows to earn four IPs,fulfilling the requirements of this cri-terium[25].The aim of this paper is to develop a rapid and robust method for the determination of low concentrations of glyphosate,its principal degradation product,AMPA,and glufosinate in water and soil by SPE–LC–ESI-MS/MS,that fulfil the requirements of excellent sensitivity and unequiv-ocal confirmation of the residues detected according to the European Union guidelines.Following the most widely accepted criteria,four IPs will be achieved,thus avoiding the possibility of reporting false positives.2.Experimental2.1.ChemicalsGlyphosate(98%),glufosinate(99%)and AMPA(99%) reference standards were purchased from Dr Ehrenstorfer (Augsburg,Germany),Riedel-de-H¨a en(Seelze,Germany) and Sigma(St Louis,MO,USA),respectively.Isotope-labeled glyphosate(1,2-13C,15N),used as surrogate inter-nal standard(IS),was purchased from Dr Ehrenstorfer. Analytical reagent-grade disodium tetraborate decahydrate was obtained from Scharlab(Barcelona,Spain)and9-fluorenylmethylchloroformate(FMOC-Cl)was purchased from Sigma.Reagent-grade hydrochloric acid,formic acid, potassium hydroxide(KOH),acetic acid(HAc)and ammo-nium acetate(NH4Ac)as well as LC-grade acetonitrile were purchased from Scharlab.LC-grade water was obtained by purifying demineralised water in a Nanopure II system(Barn-stead Newton,MA,USA).Standard stock solutions were prepared dissolving approx-imately50mg powder,accurately weighted,in100mL of water obtaining afinal concentration of approximately 500mg/L.A50-mg/L composite standard was prepared in water by mixing and diluting the individual standard stock solutions.Standard working solutions for the LC–MS/MS analysis and for fortification of samples were prepared by dilution of the50-mg/L composite standard with water.All standard solutions were stored in nonsilanized glass.The isotope-labeled glyphosate was purchased as1.1mL of100-␮g/mL stock solution in water.A11-␮g/mL stan-dard solution was prepared by dissolving1.1mL of the stock solution in10mL of water.Standard working solutions were prepared by diluting the intermediate standard solution with water.Solutions of5%borate buffer(pH approximately9)in HPLC-grade water and solutions containing12,000mg/L of FMOC-Cl in acetonitrile were used for the derivatization step prior to the analysis.2.2.InstrumentationFor the analysis of water samples,the mass spectrometer was interfaced to a LC system based on a233XL autosam-pler with a loop of4.3mL(Gilson,Villiers-le-Bel,France) and2pumps:an Agilent1100(Agilent,Waldbron,Germany) binary pump used to condition and wash the cartridge(P-1) and a Waters Alliance2695(Waters,Milford,MA,USA)qua-ternary pump used for the chomatographic separation(P-2), as can be seen elsewhere[24].The SPE preconcentration was performed using an Oasis HLB cartridge,20mm×2.1mm i.d.(Waters),as C-1.For the LC separation,a Discovery col-umn C18,5␮m50×2.0mm i.d.(Supelco,Bellefonte,PA, USA),was used as C-2.Mobile phase consisted of water pH 2.5(adjusted with formic acid)in P-1,and mixtures of aque-ous5mM acetic acid/ammonium acetate(pH4.8)water and acetonitrile in P-2.For the analysis of soil samples,the mass spectrometer was directly interfaced to the Waters Alliance2695(Waters) quaternary pump.The mobile phases and the column used were the same as in the case of water samples.A Quattro LC(quadrupole-hexapole-quadrupole)mass spectrometer(Micromass,Manchester,UK)with an orthog-onal Z-spray-electrospray interface was used.Drying gas as well as nebulising gas was nitrogen,generated from pressur-ized air in a NG-7nitrogen generator(Aquilo,Etten-Leur, NL).The nebuliser gasflow was set to approximately80L/h and the desolvation gasflow to800–900L/h.Datastation operating software was MassLynx v4.0.For operation in MS/MS mode,collision gas was Argon 99.995%(Carburos Metalicos,Valencia,Spain)with a pres-sure of approximately1×10−3mbar in the collision cell. Capillary voltage of3.5kV was used in positive ionization mode.The interface temperature was set to350◦C and the source temperature to120◦C.Dwell times of0.17s/scan were chosen.2.3.SPE procedureThe conditioning of the Oasis cartridge was performed with LC-grade water at pH2.5at aflow-rate of1mL/min for7min.An aliquot of4.3mL of water sample was pre-concentrated(1mL/min)into the cartridge and washed with acidified LC-grade water during4min.After washing,the sample was transferred in backflush mode to the C-2column and a gradient in P-2started.2.4.LC procedureTo perform the chromatographic separation,the gra-dient used in P-2was water5mM HAc/NH4Ac(pH 4.8)–acetonitrile,where the percentage of organic modifier was changed as follows:0min,10%;5min,10%;5.1min,148M.Ib´a˜n ez et al./J.Chromatogr.A1081(2005)145–15590%;9min,90%;9.1min,10%;14min,10%.The chro-matographic separations were completed within20min. 2.5.Sample procedureThe derivatization procedure was based on Sancho et al. [14,15](see Fig.1),with slight modifications.2.5.1.Water samplesGround and surface water samples were collected in plas-tic bottles from different sites of the Valencian Mediterranean region and stored in a freezer at−18◦C until analysis.Ten millilitre of water sample was introduced into a glass tube together with100␮L of isotope-labeled glyphosate standard (110␮g/L).Samples were derivatised by adding0.6mL of 5%borate buffer(pH9)followed by0.6mL of FMOC-Cl reagent(12000mg/L),and allowing the reaction to take place overnight at room temperature.After that,samples werefiltered through a0.45␮m syringefilter and acidified with hydrochloric acid until pH1.5.Finally,4.3mL of the acidified derivatized samples were directly injected into the SPE–LC–ESI-MS/MS system.Fortification of surface or ground waters for recovery experiments was performed by adding1mL of5or50ng/mL mixture solutions to100mL of blank water sample in order to yield fortification levels of50or500ng/L,respec-tively.2.5.2.Soil samplesSoil samples was collected from a public garden,sus-pected to have been contaminated by glyphosate.Air-dried soil samples were homogenized and5.0g subsamples were transferred to centrifuge tubes(50mL).Samples were extracted by shaking with0.6M KOH(10mL)on a mechan-ical shaker for30min,and then centrifuged at3500rpm for 30min.The alkaline sample extracted was separated and neu-tralized by adding drops of HCl6M and0.6M until pH7, approximately.After that,the neutralized supernatant was 10-fold diluted with HPLC-grade water.The derivatization step was performed as follows:2-mL of the10-fold diluted supernatant was pipetted into a glass tube together with 120␮L of the labelled internal standard(1.10mg/L),120␮L of5%borate buffer(pH9)and120␮L of FMOC-Cl reagent (12000mg/L).The tube was swirled and left overnight at room temperature.After that,samples werefiltered through a0.45␮m syringefilter and acidified with hydrochloric acid until pH1.5.Finally,50␮L of the acidified deriva-tized extract was directly injected into the LC–ESI-MS/MS system.Fortification of soil samples for recovery experiments was performed by adding1mL of250ng/mL or2500ng/mL mix-ture solutions to5.0g of blank soil sample in order to yield fortification levels of0.05mg/kg or0.5mg/kg,respectively. Samples were equilibrated for1h prior to extraction.AMPA and glyphosate were quantified using isotope labelled glyphosate as internal standard,in both water and soil samples.In the case of glufosinate,quantification was performed with external calibration.2.6.Validation studyLinearity of the method was evaluated analysing eight standard solutions by duplicate,in the range25–5000ng/L for water samples,and in the range1–500␮g/L for soil extracts.Precision(repeatability,expressed as relative standard deviation,in%)and recoveries were determined within day by analysing fortified blank samples in quintupli-cate.This experiment was performed at two spiking lev-els:50and500ng/L in water,and0.05and0.5mg/kg in soil.The limits of detection(LOD),defined as the lowest concentration that the analytical process can reliably dif-ferentiate from background levels,were obtained when the signal was three times the average of background noise in the chromatogram at the lowest analyte concentration assayed.The limits of quantification(LOQ)were estab-lished as the lowest concentration assayed and validated, which gave satisfactory recovery(70–120%)and precision (<15%RSD).The specificity of the method was evaluated by analysing a blank procedure,a processed blank sample,and a blank sam-ple spiked at the lowest fortification level assayed(LOQ),i.e. 50ng/L in water and0.05mg/kg in soil.Under these condi-tions,the response obtained for both the blank procedure and the blank samples should not exceed30%of the response corresponding to the LOQ.2.7.Data evaluationTo ensure the quality of the analysis when processing real-world samples,blank samples fortified at the LOQ and10×LOQ concentration levels(50and500ng/L for waters,and 0.05and0.5mg/kg for soils)were used as quality controls (QC)distributed along the batch of samples every three-four injections.The quantification of the sample batch was con-sidered satisfactory if the QC recoveries were in the range of 70–120%.The values found in real samples were confirmed by means of the two transitions selected for each compound. In this way,quantification was carried out independently with each transition(see MS Optimisation),accepting a deviation of±20%in the concentrations obtained with both transi-tions.3.Results and discussion3.1.MS optimisationFull-scan MS spectra and product-ion MS/MS spectra of the FMOC derivatives of glyphosate,glufosinate and AMPA were recorded in both positive and negative ionisation modes.M.Ib´a ˜n ez et al./J.Chromatogr.A 1081(2005)145–155149Fig.2.The positive ion electrospray full scan mass spectrum (top)and product ion spectra (bottom)of (a)AMPA-FMOC,(b)glyphosate-FMOC and (c)glufosinate-FMOC,obtained from the chromatographic peak of 10mg/L standard solution of each compound,previously derivatizated.Spectra were obtained from the chromatographic peak of 10mg/L standard solution of each compound,previously derivatized.Although these compounds have been traditionally recorded in negative ion mode [9,10],in our work the sensi-tivity in positive ion mode was found to be approximately two times higher.Moreover,the product ions observed in negative ion mode were due to neutral unspecific losses of FMOC,or FMOC plus water.Thus,any isobaric compound that could have been derivatized with FMOC and also presented a water loss,would show the same product ions in its MS/MS spec-tra,being therefore not very selective.For all these reasons,positive ion mode was selected.The positive-ion electrospray full scan spectrum of AMPA-FMOC at a cone of 30V showed a base peak at m /z 334corresponding to the protonated derivatized molecule [M +H]+.The MS/MS spectra showed three abundant frag-ments at m /z 179,156and 112(Fig.2a).As can be seen in Fig.3a,fragments at m /z 179,m /z 156(M-178)and m /z 112(M-222)would appear in any isobaric amine that could have been derivatized with FMOC.As there were not significant differences in the selectivity of these transitions,the criterium applied for their selection was the sensitivity,choosing the two most sensitive ones.The positive-ion electrospray full scan spectrum of glyphosate-FMOC at a cone of 30V showed a peak at m /z 392corresponding to the protonated derivatized molecule [M +H]+.The MS/MS spectra showed abundant fragments at m /z 214,179,170and 88(Fig.2b).The fragments at m /z 179and the fragments at m /z 214(M-178)and m /z 170(M-222)would appear in any isobaric amine that could have been derivatized with FMOC (Fig.3a).Thus,the selected reac-tion monitoring (SRM)transitions chosen were 392→88for quantification as the most selective (see Fig.3b)andTable 1Optimised MS/MS parameters for the FMOC derivatives of glyphosate,AMPA,glufosinate and internal standard,selected for the residue analysis of water and soil Compound Cone voltage (V)Precursor ion (m /z )Product ion (m /z )a Collision energy (eV)Glyphosate-FMOC 30392.0Q 88.120q 214.110Glufosinate-FMOC 30404.0Q 136.125q 208.210AMPA-FMOC30334.0Q 179.120q 112.115Isotope-labeled glyphosate-FMOC30395.0Q 91.120q 217.110aQ ,Transition used for quantification;q :transition used for confirmation.150M.Ib´a ˜n ez et al./J.Chromatogr.A 1081(2005)145–155Fig.3.(a)Common fragmentation pathway for the three derivatised compounds;(b)specific fragmentation pathway for glyphosate and glufosinate.392→214for confirmation as it was the most sensitiveamong the less selective.In the case of glufosinate,the positive-ion electrospray full scan spectrum showed a peak at m /z 404corresponding to the protonated molecule of glufosinate-FMOC.The MS/MS spectrum showed four abundant fragments at m /z 208,182(M-222),179and m /z 136(Fig.2c).We choose the most selective transitions:404→208and 404→136(see Fig.3b)despite their lower sensitivity.The selected reaction monitoring (SRM)transitions cho-sen for the residue determination of the three compounds,as well as the optimised MS/MS parameters,are shown in Table 1.3.2.Method optimisationFirstly,several attempts were carried out in order to deter-mine these compounds directly,i.e.without any previousM.Ib´a˜n ez et al./J.Chromatogr.A1081(2005)145–155151derivatization.For this purpose we checked Hydrophilic Interaction Chromatography using an Atlantis TM HILIC 5␮m Silica Column(100mm×2.1mm i.d.,Waters).This column offers superior retention for very polar compounds that are not well retained under reversed-phase conditions. Although the retention obtained with this column at acidic pH was satisfactory,we observed poor sensitivity,making necessary a preconcentration step.We did not try to perform such a preconcentration because this step is difficult for sub-ppb levels of glyphosate and forces one to a higher sample manipulation.Additionally,the conditions to obtain satisfac-tory retention and peak shape were very specific and changed drastically when changing either pH of the sample or modifier concentration in the mobile phase,decreasing the robustness of the method.For these reasons,a derivatisation procedure was carried out in order to increase the retention of analytes in the most common RPLC cartridges and to work under no so strict conditions.Derivatization procedures with FMOC-Cl have already been reported in the literature[9–15].Due to the low sol-ubility and stability of FMOC-Cl in water,this reagent is usually prepared in acetonitrile.Normally the high con-centration of FMOC required for the derivatization,makes that the derivatized sample presents a high percentage of acetonitrile.Thus,a dilution step with water is necessary to reduce the organic percentage[14],with the subse-quent loss of sensitivity,to retain glyphosate,glufosinate and AMPA in the cartridge due to the high polar charac-ter of these compounds,even derivatized.In this paper,we decreased the volume of the FMOC solution used but increas-ing its concentration and also the volume of water sample derivatized with the aim of minimizing the dilution factor. The effect of adding different FMOC concentrations with different reaction times was studied.The best results for both,water and soil samples,were obtained after perform-ing the reaction overnight with a FMOC concentration of 12,000mg/L.On the other hand,as the borate solution could not buffer properly the alkaline sample extract,a neutralizing step was necessary before the derivatization.Any attempt offixing the volume of HCl necessary to neutralize the KOH excess failed due to the different nature of the soils.Therefore,this step was done manually adding drops of HCl6M and0.6M until pH around7.Once the derivatization reaction took place overnight, hydrochloric acid was added to stop the reaction,by low-ering the pH.In soil samples,after direct injection of50␮L of the derivatized acidified extract,recoveries around25%with RSD up to80%were obtained for the three analytes,showing a severe matrix effect in both the MS instrument and/or the derivatization procedure.Among the solutions described to solve this problem(see Section1),the increase of the sample treatment was not considered as the best strategy for monitor-ing programs where rapid methods are preferred.Moreover, the use of matrix-matched standards calibration is not a robust approach when environmental samples are analysed,due to their different origin and composition,making the selection of a blank matrix difficult.Thus,the use of internal stan-dards(IS)was tested,but only isotope-labelled glyphosate was commercially available.As expected,the use of this IS improved accuracy and pre-cision for glyphosate as it compensated the matrix effects,due to the similar chemical behaviour of analyte and IS.However, still ionization inhibition occurred lowering the sensitivity of the overall analytical procedure.In the case of AMPA and glufosinate,although better recoveries were obtained(around 116–127%),the RSDs were still unacceptable(higher than 15%).Therefore,the dilution of soil extracts with LC grade water was assayed as a fast and simple way to minimize matrix interferences.Thus,five soil samples of different origins were fortified at the0.5mg/kg and their extracts derivatized and,10-fold and20-fold diluted with water.According to our results(see Table2),10-and20-fold dilution would be adequate for accurate quantification,even without internal standard.However,the use of internal standard improved the RSDs,especially for glyphosate.In the case of glufosinate, quantification with labelled glyphosate IS did not improve the results.A similar situation has been previously reported in literature,when using analogues IS,demonstrating the dif-ficulty of selecting an adequate IS when the labelled analyte is not available[28].Finally,glyphosate and AMPA were quantified using internal standard meanwhile glufosinate was quantified with external standard calibration.A10-fold dilu-tion of the extract was chosen as it led to the best LODs.In regard to water samples,after injection of4.3mL of the derivatized sample into the SPE–LC–MS/MS,recoveriesTable2Effect of dilution of soil extracts previously to the derivatization step on the recovery and reproducibility of the method(n=5)a Compound Without dilution10-Fold dilution20-Fold dilution%Recovery b (%RSD)%Recovery c(%RSD)%Recovery b(%RSD)%Recovery c(%RSD)%Recovery b(%RSD)%Recovery c(%RSD)Glyphosate25(79)97(6)83(24)98(3)83(23)91(11) AMPA28(46)127(27)87(9)98(11)89(8)98(10) Glufosinate27(56)116(18)94(8)118(19)92(8)107(9)a Five different soil samples,spiked at0.5mg/kg each.b Quantification without internal standard.c Quantification with internal standard.。

55第19卷 第1期 2017 年 1 月辽宁中医药大学学报JOURNAL OF LIAONING UNIVERSITY OF TCMVol. 19 No. 1 Jan .，2017细胞衰老是指正常的细胞在通路的调控下能够不可逆的进入生长停滞期的一种状态[1]。

细胞衰老涉及DNA 的损伤与修复、线粒体的能量代谢以及相关基因的调控等方面[2]。

随着我国人口老龄化进程的加快，细胞衰老问题不仅是一个生物问题，更成为了一个重大的社会问题，所以对于延缓细胞衰老的研究更有现实意义。

五味子为木兰科植物五味子[Schisandra chinensis （Turcz.）Baill]的干燥成熟果实，其果实入药，味酸甘性温，入肺、心、肾经，有敛肺固涩、益气生津及补肾宁心的功效[3]。

现代药理学研究表明，五味子具有保肝[4]、抗缺氧、抗疲劳[5]和抗肿瘤[6]等作用。

高文荣等[7]证实五味子水提取液能够对D-半乳糖所致的衰老神经细胞具有保护作用，但是五味子水提取液对t-BHP 所造成的神经元衰老笔者还未见相关报道。

所以本研究在成功培养小鼠原代皮层神经元基础上，观察五味子水提取液对t-BHP 导致的神经元衰老的作用。

1 材料与方法1.1 动物昆明种小鼠，购自辽宁长生生物技术有限公司，合格证号：SCXK（辽）2010-001，光明∶黑暗=1∶1，室温（22±2）℃，相对湿度55%~65%。

将怀孕的母鼠单独放置在一个鼠笼中，待自然分娩后取新生小鼠用于实验。

1.2 试剂五味子水提取液（由辽宁中医药大学制剂实验室提供），用含有10% FBS（fetal calf serum，胎牛血清，Gibco 公司）和1% P/S（penicillin-strepotomycin，青-链霉素，Thermo 公司）的DMEM（Dulbecco's五味子水提取液对叔丁基过氧化氢诱导神经元衰老保护作用赵坚毅，田立东（辽宁中医药大学附属医院，辽宁 沈阳 110032）摘 要：目的：探讨五味子水提取液（SWE）对叔丁基过氧化氢诱导的神经元衰老的保护作用并探讨其机制。

装备环境工程第20卷第12期·70·EQUIPMENT ENVIRONMENTAL ENGINEERING2023年12月氟醚橡胶在不同介质下的热老化行为与机理研究刘俊邦1，张少锋1，李璞2，张洪彬1，陈荻云1，唐庆云1*（1.工业和信息化部电子第五研究所，广州 510610；2.中国航发湖南动力机械研究所，湖南 株洲 412000）摘要：目的对氟醚橡胶FM-2D在空气与飞马Ⅱ号润滑油中的热老化行为与机理进行研究。

方法开展氟醚橡胶高温贮存试验，在热氧、热油的介质环境下，研究氟醚橡胶的力学性能退化规律。

试验后对样品的拉伸性能、压缩性能以及硬度进行检测，并且利用傅里叶红外光谱仪、扫描电子显微镜以及X射线电子能谱对试验后样品进行检测。

结果通过热老化试验，发现氟醚橡胶在200 ℃以下能够长期维持较好的力学性能。

试验温度在200 ℃以上，氟醚橡胶的力学性能出现明显退化趋势，并且在热空气与热油中的老化趋势不同。

在220 ℃的热空气老化31 d后，氟醚橡胶的拉伸强度下降27.0%，断裂伸长率增大89.8%，压缩应力松弛率为34.6%，硬度下降8.7%。

在220 ℃的热油老化31 d后，氟醚橡胶的拉伸强度下降85.9%，断裂伸长率下降83.9%，压缩应力松弛率为‒17.5%，硬度上升4.2%。

结论在热空气老化过程中，橡胶分子链受热氧影响发生断裂，使其强度下降；在热油老化过程中，油介质和高温的耦合作用使橡胶的交联网络失效，橡胶发硬变脆。

关键词：氟醚橡胶；热老化；力学性能；X射线光电子能谱中图分类号：TN06 文献标识码：A 文章编号：1672-9242(2023)12-0070-08DOI：10.7643/ issn.1672-9242.2023.12.009Thermal Aging Behavior and Mechanism of Fluoroether Rubber under Different Media LIU Jun-bang1, ZHANG Shao-feng1, LI Pu2, ZHANG Hong-bin1, CHEN Di-yun1, TANG Qing-yun1*(1. Electronic Fifth Institute of the Ministry of Industry and Information Technology, Guangzhou 510610, China;2. China Aerospace Hunan Power Machinery Research Institute, Hunan Zhuzhou 412000, China)ABSTRACT: The work aims to study the thermal aging behavior and mechanism of fluoroether rubber FM-2D in air and Pegasus II lubricating oil. The storage test of fluoroether rubber at high temperature was carried out, and the degradation law of mechanical properties of fluoroether rubber was investigated in air and oil. The tensile properties, compressive properties and hardness of the samples were tested after the aging test. A Fourier infrared spectrometer, a scanning electron microscope and an X-ray electron spectroscopy were used to detect and analyze the samples after the test to explore the aging mechanism. The re-sult showed that fluoroether rubber could maintain good mechanical properties for a long time at 200 ℃. While when the tem-perature was above 200 ℃, the mechanical properties of fluoroether rubber degraded obviously. After 31 days of aging in hot air收稿日期：2023-10-31；修订日期：2023-12-11Received：2023-10-31；Revised：2023-12-11引文格式：刘俊邦, 张少锋, 李璞, 等. 氟醚橡胶在不同介质下的热老化行为与机理研究[J]. 装备环境工程, 2023, 20(12): 70-77.LIU Jun-bang, ZHANG Shao-feng, LI Pu, et al. Thermal Aging Behavior and Mechanism of Fluoroether Rubber under Different Media[J]. Equipment Environmental Engineering, 2023, 20(12): 70-77.第20卷第12期刘俊邦，等：氟醚橡胶在不同介质下的热老化行为与机理研究·71·at 220 ℃, the tensile strength of fluoroether rubber decreased by 27.0%, the elongation at break increased by 89.8%, the relaxa-tion rate of compressive stress was 34.6%, and the hardness decreased by 8.7%. After 31 days of hot oil aging at 220 ℃, the tensile strength of fluoroether rubber decreased by 85.9%, the elongation at break decreased by 83.9%, the relaxation rate of compressive stress was ‒17.5%, and the hardness increased by 4.2%. Through analysis and characterization, it is founded that the molecular chain of rubber is broken under the influence of hot oxygen during the aging process of hot air, and the strength of rubber decreases. In hot oil aging, the coupling effect of oil medium and high temperature makes the crosslinking network of rubber fail, and the rubber becomes hard and brittle.KEY WORDS: fluoroether rubber; FM-2D; thermal aging; mechanical properties; X-ray photoelectron spectroscopy橡胶以O形圈、垫片的形式被应用于液体和气体的密封，广泛应用在机械、化工、航空航天、汽车等领域[1-4]。

机电工程专业英语答案【篇一：机电工程专业英语】r (rotating member) in an electric motor has rotational inertia,and a torque is required to bring it up to speed when the motoris started. if the motor shaft is rigidly connected to a load witha large rotational inertia, and the motor is started suddenly by closing a switch, the motor may not have sufficient torquecapacity to bring the motor shaft up to speed before thewindings in the motor are burned out by the excessive current demands . a clutch between the motor and the load shafts will restrict the starting torque on the motor to that required to accelerate the rotor and parts of the clutch only.电机的转子（转动元件之一）是有惯性的。

当电机启动时，需要一个力矩使转子提升速度。

如果电机轴与负荷是刚性连接，就会有更大的惯性。

这样启动，电机在还没有足够的力矩使转子提升到一定速度，可能就被过电流烧毁了线圈。

在电机和负荷之间的离合器，会限制启动转矩来保证有足够的力矩只加速转子和离合器。

有些机床，可以非常方便的在电机连续运转时，通过操作离合器来启动或停止机器的。

LUBRICATIONAND LUBRICANTS1.IntroductionLubrication is a process in which afilm of lubricant is inserted between rubbing surfaces for the purpose of controlling friction and/or to reduce wear of the sur-faces.Thesefilms are designed to minimize contact between the rubbing surfaces and to shear easily so that the frictional force opposing the rubbing motion is low. Lubricants may be liquids,solids,gases,or greases.Lubricating oils and greases contain refined or synthesized base oils from animal,vegetable or mineral (petroleum)origin,and a variety of additives to improve their lubricating and other characteristics.Lubrication is a major component of tribology,defined as the science and technology concerned with interacting surfaces in relative motion,including fric-tion,lubrication,wear and erosion(1).Tribology and lubrication are ancient arts.In his splendid History of Tribo-logy(2),Professor Dowson traces the development of these arts and sciences,and describes the outstanding artists and scientists responsible,from the paleolithic age to the end of the twentieth century.He reports archeological evidence that bitumen was used to lubricate potters wheels5000years ago.Water-lubricated sliding bearings were used in Egypt$2400BC to transport large objects.A char-iot wheel from$1400BC was found with traces of tallow as lubricant,and the Chinese had lubricated metal wheel bearings with leather seals to hold the lubri-cant in place in the fourth century BC(2).The word‘‘tribology’’first appeared in Lubrication(Tribology)Education and Research—A Report on the Present Position and Industries Needs,Depart-ment of Education and Science(UK),1966.This is often called The Jost Report, after H.Peter Jost,the chairman of the British Lubrication Engineering Work-ing Group,which prepared the report.The word is derived from the Greek tribein,meaning‘‘to rub’’,and logos,meaning‘‘reading’’or‘‘study’’.Tribology is literally the study of rubbing.The Working Group defined it more precisely as‘‘the science and technology of interacting surfaces in relative motion and the practices related thereto’’(3).The Jost Report was part of an effort to focus attention on the‘‘scientific, technological,economic and environmental issues’’(2)involved in the study and practice of tribology.Another purpose was to bring together the many, and often splintered engineering and scientific disciplines that deal with this technology.Dowson speculates that the dramatic progress in thisfield in the final third of the twentieth century may have been significantly influenced by these efforts in the1960s(2).The1966report by the British Lubrication Engineering Working Group demonstrated to industry and government the impact of friction,wear,and lubri-cation on the nation’s economy,and the value of further research in tribology. That report showed,eg,that the most significant value of better lubrication (91%)comes from increased productivity,lower maintenance and replacement costs,and lower investment cost.Direct energy savings(5%),and savings in the cost of lubrication,in manpower and material(4%),account for the remainder.1Kirk-Othmer Encyclopedia of Chemical Technology.Copyright John Wiley&Sons,Inc.All rights reserved.2LUBRICATION AND LUBRICANTS Vol.15 Tribology is a multidisciplinary science that embraces lubrication,friction, wear,properties of lubricants,surface characterization,bearing materials,and the selection and design of lubricating systems.The lubrication engineer would add to this list lubricant and coolant selection,plant lubrication and maintenance programs,and machine condition monitoring.2.Fundamentals of LubricationTribology,by definition,is concerned with interacting surfaces in relative motion.It is appropriate,therefore,to begin the discussion of lubrication funda-mentals by describing the characteristics of tribological surfaces.2.1.The Nature of Interacting Surfaces in Relative Motion.Tribo-logical surfaces are the load-bearing surfaces on the moving parts of machines. They include surfaces on crankshaft rod and main bearings,radial and thrust bearings on steam and gas turbines,cams and valve lifters,pistons and cylin-ders,natural and artificial hip joints,ball and roller bearings,machine tool slideways,cutting tools,magnetic information storage devices,and microelectro-mechanical systems(MEMS).Despite their appearance andfinishing efforts, these surfaces are not perfectly smooth.There are microscopic irregularities; gently sloping hills and valleys called asperities on them.If an imaginary surface is drawn through a real surface,such that the volume of all of the material above the imaginary surface is equal to the volume of voids below that surface,the roughness of the real surface,R a,can be defined asR a¼ðj y1jþj y2jþÁÁÁþj y n jÞ=nð1ÞWhere R a is the center line or arithmetic average of the absolute distances,y i, from the imaginary surface(mean line)for a given sampling length(usually 0.80mm).Roughness(R a)values of machined surfaces range from0.025m m for ball bearing surfaces to25m m clearance surfaces on rough machine parts(4–6). The roughness of computer hard disk surfaces is measured in angstroms(A˚)or nanometers(nm)(7).The total profile of a surface consists of a‘‘waviness’’and a roughness com-ponent.The parameter R a,although it is the most common measure of surface roughness,is insensitive to the shape or waviness of the profile.A more useful parameter is the root-mean-square(rms)roughness,R q.R q¼½ðy21þy22þÁÁÁþy2nÞ=n 1=2ð2ÞWhere R q is the rms deviation of y i from the mean line for a given sampling length(4).The rms roughness of computer hard disk surfaces is<2nm(7).The most repeatable of the roughness parameters is the10points height, R z.Vol.15LUBRICATION AND LUBRICANTS3 R z¼½ðP1þP2þÁÁÁþP5ÞÀðV1þV2þÁÁÁþV5Þ =5ð3ÞWhere R z is the average distance between thefive highest peaks(P i)and thefive deepest valleys(V i)within the sampling length.It is also linked with the machin-ing parameter S2/8r,where S is the feed rate and r is the tool radius(4).Another index of roughness is R t,the maximum peak-to-valley height.R t¼R pþR vð4ÞWhere R p is the maximum peak height and R v is the maximum valley depth within the sampling length(4).The description of the test disk used in the ASTM D6425-02test method for measuring friction and wear illustrates the impact of surface texture on these quantities(8)and is shown below and used with ASTM’s permission.Test Disk,AISI52100Steel,62Æ1HRC Hardness.The surfaces of the disk are lapped and free of lapping raw materials.The topography of the disk will be determined by four values:0.005m m<R z>0.65m m;0.035m m<R a>0.050m m;0.020m m<R p>0.035m m;0.050m m<R v>0.075m mFour different measures of surface topography are specified for the disk in order to get acceptable reproducibility of the test method(9).Approximate roughness indexes obtained with various metal-working processes areProduction process R t,m m R a,m mturning 4.00–25.00.500–3.0grinding 2.00–6.00.400–0.8milling 1.50–20.00.200–2.0boring0.50–20.00.050–1.6honing0.03–1.00.015–0.2lapping0.03–0.60.015–0.1Engineering surfaces also differ in composition from the underlying bulk material.A metal bearing,eg,will have a work hardened layer at the surface, over which an oxide layer forms,on top of which is an adsorbed layer of moisture and gases.When two such surfaces come in moving contact,their surface struc-tures,compositions,and the interaction between opposing asperities accounts for a major portion of the friction between them and much of the wear that inevita-bly occurs(10–12).For example,without the oxide and adsorbed layers,coefficients of friction>4have been measured in a vacuum of0.133mPa on surfaces cleaned by abrasive cloth and heated.The coefficient decreased considerably when oxy-gen was admitted to a pressure of0.133Pa(13).The oxide and adsorbed layers on metal surfaces can,therefore,be considered as lubricatingfilms.2.2.Friction.When two of these surfaces are brought together,they initially touch at the highest asperities.The load,N,normal to the surfaces at4LUBRICATION AND LUBRICANTS Vol.15the contact points causes the asperities to deform until the pressure in the result-ing contact areas just equals the yield pressure,p,of the asperities.The sum of these contact areas is the real contact area,A r.The yield pressure is equivalent to the Brinell Hardness Number(BHN),in consistent units,measured at the surface of the material(4).A r¼N=p¼N=BHNð5ÞThe real area of contact is a minute fraction of the total surface area.For example,with a typical bearing contact stress of3MPa and a bronze bearing asperity yield pressure of500MPa,<1.0%of the nominal area would involve asperity contact(14).As the load on the surfaces increases,the asperities continue to deform,the softer surface more than the other.More of the asperities come in contact and the real area of contact grows.The opposing surfaces also tend to adhere or bond to each other in the contact area.The shear strength of these bonds depends on the time of contact and the difference in composition of the two surfaces.Sliding of one of these nonlubricated surfaces across the other requires a friction force,F,to displace the contacting asperities.This force includes several components,among them:a shear or adhesion component arising from bonding of the contacting asperities;a plowing or deformation component,arising from the interlocking of asperities;a lifting component to raise asperities over the roughness of the mating surfaces.The shearing component,F s,may account for90%or more of the total fric-tion force(14).This component is proportional to the shear strength,s,of the asperity junctions:F s¼A r sð6ÞMore detailed descriptions of surface texture,surface structure,and compo-sition and the real area of contact will be found in Refs.(4–6,12,13,15,16).2.3.Coefficient of Friction.The coefficient of friction,f,of a pair of con-tacting surfaces is defined as the ratio of the total frictional force to the normal force or load.It can also be expressed as the ratio of shear strength,s,to the yield pressure,p,at the asperity junctions.f¼F=N¼s=pð7ÞIf there is a lubricatingfilm on the surfaces,the coefficient of friction is the ratio of the shear strength of the surfacefilm,s f,to the yield pressure,p m of the substrate or backing material.f¼s f=p mð8ÞIf a shear force is gradually applied to one of two dry,unlubricated surfaces in contact,the surface will not move until the force is great enough to overcomeVol.15LUBRICATION AND LUBRICANTS5 the shear strength of the asperity contacts.The ratio of the shear force required to start motion to the normal force on the surfaces is the static coefficient of friction.Once motion starts,less force is needed to keep the surface moving at a constant velocity.The coefficient of friction during sliding is the kinetic or dynamic coefficient.The static coefficient measured for a hard steel surface on another hard steel surface is0.78.The dynamic coefficient measured for hard steel on hard steel is0.42.When a thinfilm of light mineral oil is applied to these surfaces, the static coefficient drops to0.23.The dynamic coefficient with a light oilfilm drops to$0.1.Adding a friction modifier to the oil can reduce or reverse the dif-ference between the two coefficients.Adding stearic acid to the lubricant,eg,for hard steel on hard steel,reduces the static coefficient to0.0052,which is lower than the dynamic coefficient,0.029(17).An extensive Friction and Wear Databank is found in Ref.18.Tables of the coefficient of friction values for a wide variety of material combinations are also available in Refs.19and20and many other sources.These data,however, should be used with caution.The coefficient of friction varies with changes in humidity,gas pressure,time,temperature,sliding speed,surface quality, the shape of the contact region,the method of testing,and other variables. Where high reliability is needed,the friction should be measured using a proto-type device under design conditions(20).2.4.Wear.The principal types of wear in sliding contacts are adhesive, abrasive,and corrosive wear.Fatigue wear occurs in concentrated contacts(ball and roller bearings,gears,cams,and automotive valve lifters)under the combi-nation of sliding and rolling(21).The Archard equation reported by Rabinowicz(21)gives a simple,quanti-tative relationship for predicting the adhesive wear rate:V¼kNx=pð9Þwhere V¼wear volume,k¼wear coefficient,N¼normal load,x¼sliding dis-tance,p¼yield stress or indentation hardness.Values of k for several unlubricated material combinations are shown in Table1(14).Others will be found in Ref.18and in Refs.(21–24).Adhesive wear is material separated or transferred during the shearing of asperity contacts.These wear particles,and other particulate surface contami-nants that are hard enough to damage the surface,cause abrasive wear.Abra-sive wear is the removal of material by ploughing,cutting,or scratching.Its rate generally obeys equation9and the wear coefficients tend to be higher than the adhesive coefficients(21).Corrosive wear is the wearing away of the products of galvanic or chemical corrosion of the surface.There is no simple equation that characterizes this type of wear.Current broader discussions of the friction and wear phenomena are found in Refs.13,25,and26.2.5.Viscosity.Viscosity,or resistance toflow is the most important property of a lubricating oil.It was defined by Newton(27)as the ratio of the6LUBRICATION AND LUBRICANTS Vol.15 shear stress,T,divided by the shear rate,dU/dh,in afluid duringflow. Newton’s law of viscosity is given in equation10(28).T¼F s=A s¼ ÁdU=dhð10ÞThefluid in contact with the surface of the moving plate has the same velo-city,U,as the plate.Thefluid in contact with the stationary plate has zero velo-city.There is,therefore,a shear stress,T,on thefluid equal to the force,F s, required to keep the plate moving divided by the area,A s,of the moving plate, and is proportional to the velocity gradient,dU/dh,of thefluid.The parameterF s is a frictional force and the coefficient,m,is the dynamic viscosity of thefluid(29).The unit of dynamic viscosity in the System International(SI)is pascal-second(PaÁs).The customary unit is centipoise(cP),which is PaÁsÂ10À3.Schoff and Kamarchik(30)describe methods of measuring the viscosity of a wide variety of materials.Standard methods for measuring the dynamic viscos-ity of lubricating oil can be found in Refs.31–34.Generally,however,it is easier to measure the kinematic viscosity,v,of a lubricating oil using a capillary viscometer.Kinematic viscosity is the dynamic viscosity divided by the density,d,of thefluid at the same temperature.v¼ =dð11ÞThe customary unit for kinematic viscosity is centistoke(cSt),which is equivalent to millimeters squared per second(mm2/s).The most common method for accurate measurement of kinematic viscosity over a wide temperature range is ASTM D445(35).Older literature may report kinematic viscosities of lubricat-ing oils in Saybolt Universal Seconds(SUS).ASTM D2161-04,has been retained for the purpose of calculating kinematic viscosity in centistokes from SUS or SFS data(36).Viscosity–Temperature Relationship.The MacCoull equation,also called the Walther equation,relates the kinematic viscosity,v,of a liquid to its temperature.log log Z¼AÀBðlog TÞð12ÞWhere Z¼(vþ0.7)for2.00cSt v2Â107cSt;A and B¼constants,and T¼absolute temperature,8K¼temperature,8Cþ273.2.It is applicable to homogeneous liquid lubricants with conventionally refined hydrocarbon base oils and is valid between the cloud point at low tem-perature and the initial boiling point($3408C)at higher temperatures.(The cloud point is the temperature at which a cloud of wax crystalsfirst appears when it is cooled under conditions prescribed in ASTM D2500.)This equation is the basis of the viscosity–temperature charts described in ASTM D341(37).Oils with ester,phosphate,silicone,and synthesized hydrocarbon base oils follow the MacCoull(Walther)relationship over the range ofÀ18to1758C to within5%.Many esters,synthesized hydrocarbons,and low pour point mineral oils exhibit low temperature(À40toÀ548C)viscosities substantially below MacCoull equation predictions(38).Vol.15LUBRICATION AND LUBRICANTS7 Viscosity Index.Another widely used and accepted measure of the varia-tion of viscosity with temperature is the viscosity index(VI).The higher the VI, the lower is the variation of viscosity with temperature.The VIs for oils having values<100are calculated byVI¼100½ðLÀUÞ=ðLÀHÞ ð13Þwhere U¼kinematic viscosity at408C of the oil whose viscosity index is to be calculated;L¼kinematic viscosity at408C of a‘‘0’’VI oil with the same viscosity at1008C as the unknown;H¼kinematic viscosity at408C of a‘‘100’’VI oil with the same viscosity at1008C as the unknown.Values of H and L for viscosities of2cSt and above are given in ASTM D 2270(39).Equation13gives confusing results for VI values>100.Viscosity indexes of 100or greater are calculated by the empirical formula(39):VI¼½ððantilog NÞÀ1Þ=0:00715þ100 ð14Þwhere Y N¼H/U and Y¼kinematic viscosity at1008C of the oil whose viscosity index is to be calculated.Viscosity index is sometimes used as a measure of the quality of lubricating oil,especially for selecting base stocks for automotive engine oils and automatic transmissionfluids.This is not always applicable,however.The role of viscosity index in base stock selection is described later.Several aromatic typefluids,polyphenyl ethers,aryl phosphate esters,and halogenated aromatic hydrocarbons have negative VIs.Effect of Pressure on Viscosity.The lubricantfilm pressure in the con-centrated contact areas of rolling element bearings,gears,cams,etc,can be as high as2000–3000MPa.The viscosity of thefilm at these pressures could be a million times higher than that of the lubricating oil at atmospheric pressure, as illustrated in Fig.1,or the lubricant may have solidified(38,40).The rate of viscosity increase with pressure of a liquid lubricant varies with its composition and chemical structure and with temperature and pressure.Traction drives,found in some industrial machinery and the toroidal drives in some continuously variable transmissions(CVTs)depend on this property of tractionfluids to transfer power.Generalized pressure–temperature–viscosity relationships from extensive data on petroleum and synthetic oils are described in Refs.(14,41,42).Newtonian Versus Non-Newtonian Behavior.If the viscosity of afluid subjected to shear is independent of the rate of shear or magnitude of the shear stress,it is a Newtonianfluid.Most industrial lubricating and hydraulic oils are Newtonianfluids.If the viscosity changes with shear stress or shear rate,thefluid is non-Newtonian.This behavior is typical of multigrade engine oils and other oils con-taining polymeric viscosity improvers.The rate of decline in viscosity in a non-Newtonian lubricating oil is initially slow,then reaches a maximum,andfinally slows again.At very high shear rates, the viscosity tends to level out and approach that of the base oil.8LUBRICATION AND LUBRICANTS Vol.15 Grease also behaves in a non-Newtonian manner.At low shear rate,it acts like a high viscosity semisolid and‘‘stays in place’’.In a bearing,under high shear rate,it acts more like its base oil and supports fullfluid lubricatingfilms.2.6.Lubrication Regimes.In the fullfluidfilm regimes,the moving, load-bearing surfaces are completely separated.There is no contact between them.Resistance to motion arises solely from the internal friction of thefluid, a function of its viscosity.Adhesive wear is absent.Wear may occur from surface fatigue or from contamination of thefluid with corrosive or abrasive substances.The coefficient of friction in a liquid lubricated system is dependent on, among other things,the lubricant viscosity,the relative speed of the surfaces, and the load on the surfaces.In a journal bearing,eg,the lubricantfilm thick-ness and the coefficient of friction are functions of the dimensionless Sommerfeld bearing characteristic number S.S¼ðR2=C2ÞZN=Pð15Þwhere P is the average pressure on the bearing surface,W/2RL;Z is the dynamic viscosity, ,of thefluid;and N¼is the rotational speed of the journal,U/2p R.The relationship between the kinetic coefficient of friction and the dimen-sionless quantity,ZN/P,is illustrated in Fig.2(10).This is known as a Stribeck curve.At values of ZN/P greater than$30,lubrication is in the fullfluidfilm regime.Friction increases with increasing ZN/P because of increasing resis-tance toflow.As ZN/P is reduced,by reductions in the speed or viscosity,or by increases in load,the coefficient will reach a minimum value.Further reduc-tion in ZN/P leads to partial breakdown in thefluidfilm and lubrication is in the mixed-film regime.Friction increases as ZN/P decreases in this regime,as more and more of the load is carried by asperity contact and less byfluid-film pressure. Finally,a point is reached,as ZN/P gets smaller,where there is nofluid pres-sure,the rate of increase in the coefficient of friction starts to level out,and lubri-cation is in the thin-film boundary regime(43).Ideally,a bearing is designed to operate where the coefficient of friction is at its minimum.Hydrodynamic Lubrication Regime.Rohde(44)and Dowson(45)remind us that the basic mechanism offluid-film lubrication was explained by Reynolds (46)in1886,based on the earlier work of Petrov(47),and Tower(48).The fundamental requirements of lubrication in the hydrodynamic regime are the formation of a wedge-shapedfilm;and generation of pressure in thefilm, sufficient to keep the surfaces apart,by the motion of the surfaces themselves.The pressure distribution in the lubricatingfilm of the sliding bearing illu-strated in Fig.3(29),moving with velocity U relative to a slanted stationary pad in afluid with viscosity ,and assuming noflow out of the sides of the bearing, is(49)p¼6 UxðhÀh2Þ=h2ðh1þh2Þð16ÞVol.15LUBRICATION AND LUBRICANTS9 The total force P that the bearing will support per unit width isp¼½6 UB2=ðh1Àh2Þ2 ½lnððh1=h2Þ À2½ðh1Àh2Þ=ðh1þh2Þ ð17Þand the frictional force F required to move the slider at speed U isF¼½2 UB=ðh1Àh2Þ ½2lnðh1=h2ÞÀ3ðh1Àh2Þ=ðh1þh2Þ ð18ÞThe analysis of hydrodynamicfluidfilms assumes laminarflow in thefilm,ie,a Reynolds number,R e,<1000.R e¼U p h= ¼Uh= ð19Þwhere U¼velocity,r¼density,h¼averagefilm thickness,m¼dynamic visco-sity,n¼kinematic viscosity.Transition from laminarflow to turbulentflow starts when the Re is$1000 and theflow is completely turbulent at a Re of1600(50).In a journal bearing,the wedge is formed because the diameter of the jour-nal is smaller than that of the bearing.As the journal starts to rotate,its center-line moves away from that of the bearing.The rotating journal drags,or pumps the lubricant through the wedge,against the resistance toflow,and increases the pressure in thefluid until the journal is lifted off the bearing surface.The load carrying capacity W of a journal bearing is(51)W¼ð UR2L=C2Þ12 "=ð2þ"2Þð1À"2Þ1=2ð20Þwhere m¼lubricant viscosity,U¼journal peripheral speed,R¼journal radius, C¼clearance¼bearing radiusÀjournal radius,L¼axial length of the bearing, e¼eccentricity¼center offset distance e/clearance C.Bearings designed for hydrodynamic lubrication include journal and thrust bearings in steam and gas turbines,and main and rod bearings for automotive engine crankshafts.Elastohydrodynamic(EHD)Lubrication Regime.The shapes of sliding surface bearings designed for hydrodynamic lubrication have a high degree of conformity,a relatively large contact area,and low unit loading,such that the effect of pressure on viscosity can be neglected.In contrast,the surfaces in a roll-ing element bearing and on gear teeth are nonconforming.Surface contact is con-centrated at a point in ball bearings or along a line in roller bearings and gears. Contact pressure,therefore,is high enough to cause elastic deformation of the contacting surfaces,forming a small area of contact.The viscosity of liquid lubri-cants entering the contact area increases exponentially and may solidify.Since the viscosity of the lubricant is affected by the elastic deformation of the surfaces, as well as otherfluid properties,this lubrication regime is called elastohydrody-namic or EHD.The hydrodynamic pressure developed in the lubricant is sufficient to sepa-rate the surfaces at the leading edge of the contact area.As the lubricant is10LUBRICATION AND LUBRICANTS Vol.15 drawn into the contact,its pressure and viscosity increase further,keeping the surfaces apart.During contact,thefluid acts like an elastic solid,so that it cannot escape the contact except in the direction of rolling(52).As the lubricant comes out of the contact area,there is a sharp pressure spike,followed by a sudden pressure drop so extreme that it causes a bulge in the rolling surfaces.The minimumfilm thickness is at the location of this bulge.The pressure spike and suddenfilm restriction directly affect the rolling element fatigue life(53).The Dowson-Higginson equation for minimumfilm thickness(54,55)ish min=R¼1:6ð E0Þ0:6ð U=E0RÞ0:7ðP=E0ÞÀ0:13ð21Þwhere R is the effective radius of the contacting surfaces,a is the viscosity–pressure coefficient,E0is the effective Young’s modulus of the contacting surfaces,m is the dynamic viscosity at the inlet temperature and atmospheric pressure, U is the effective velocity,and P is the Hertz pressure at the line contact.Similar equations forfilm thickness in point contact are given by Dowson (2)and by Khonsari and Hua(53).The life of rolling element bearings is related to afilm thickness parameter,l.¼h= ð22Þwhere h is the calculated EHDfilm thickness,and s is the composite surface roughness.In the absence of chemically active additives in the lubricating oil,damage to the bearing surface occurs,and reduces the life of the bearing,if thefilm thick-ness becomes less than the height of the surface asperities(l1).The life of the bearing increases significantly at values of l>1.5(56).Hydrostatic Lubrication.In hydrostatic lubrication,fluid is pumped under pressure to the load-carrying bearing.Almost anyfluid may be used, including gases(nitrogen,helium,air),water,and liquid metals.The principle applications of hydrostatic lubrication are gas bearings,mov-ing large masses on relatively small bearing areas and for startup of heavily loaded hydrodynamic bearings.Squeeze Films.Viscous lubricantfilms do not immediately collapse when sliding stops.During the time it takes for thesefilms to be squeezed out of the contact area,they can support peak loads higher than those supported in steady-state operation.This time delay also provides damping for shock loads and shaft vibration.These squeezefilms are important in rod bearings of reciprocating automotive engines,damping in turbomachinery and in the lubri-cation of skeletal joints(hips etc).Ludema(55)estimates the time delay for a vis-cousfluid squeezed out of an elliptical contact area as1=h2¼1=h20þf½2Wða2þb2Þt =3 a3b3 gð23Þ。

lubricant翻译Lubricant：润滑剂用法：润滑剂通常用于润滑磨损或潮湿零部件，以防止运动部件之间的重叠摩擦。

1. 内燃机润滑剂是为了保护发动机部件和提高运转平稳性而所用的。

The lubricant for internal combustion engine is used to protect engine components and improve the running smoothness.2. 橡胶产品在制作过程中，常常需要润滑剂来保护它们免受磨损。

Lubricants are often needed in the manufacture of rubber products to protect them from wear.3. 润滑剂可以被喷射在这些零件上，以保持表面的光滑性和防止摩擦的发生。

Lubricants can be sprayed on these parts to maintain the smoothness of the surface and prevent friction from occurring.4. 润滑剂能够提高部件的耐久性，并降低磨损和损坏。

Lubricants can increase the durability of components and reduce wear and damage.5. 密封剂和润滑剂一起可以有效的防止水的渗入。

Sealants and lubricants can be used together toeffectively prevent water infiltration.6. 润滑剂可以有效的降低摩擦，从而减少部件之间的磨损。

Lubricants can effectively reduce friction, thus reducing wear between components.7. 我们也可以使用润滑剂来减少冲击，并均匀地扩散热量。

第44卷 第2期2024 年4月辽宁石油化工大学学报JOURNAL OF LIAONING PETROCHEMICAL UNIVERSITYVol.44 No.2Apr. 2024引用格式：黎小辉,张泽,杨露露,等.添加剂对聚脲润滑脂性能的影响[J].辽宁石油化工大学学报,2024,44(2):7-13.LI Xiaohui,ZHANG Ze,YANG Lulu,et al.Effect of Additives on the Performance of Polyurea Lubricating Grease[J].Journal of Liaoning Petrochemical University,2024,44(2):7-13.添加剂对聚脲润滑脂性能的影响黎小辉1,2，张泽1，杨露露1,3，吴韦岐4，任晓辰4，马伟华5，李广涛5（1.西安石油大学化学化工学院，陕西西安 710065； 2.陕西省绿色低碳能源材料与过程工程技术研究中心，陕西西安710065； 3.西安市高碳资源低碳化利用重点实验室，陕西西安 710065； 4.西安玛珂特新材料科技股份有限公司，陕西西安710399； 5.西安石油大佳润实业（集团）有限公司，陕西西安 710003）摘要：　采用直接法制备聚脲润滑脂，考察了五种添加剂对聚脲润滑脂极压抗磨性能的影响。

结果表明，五种添加剂均与聚脲润滑脂具有良好的相容性，且对聚脲润滑脂的胶体安定性等基本无影响，并可增强其热稳定性；添加剂可显著强化聚脲润滑脂的极压抗磨性，含硫磷的复合多效添加剂对聚脲润滑脂极压抗磨性能的提升作用相对较好。

研究结果可为聚脲润滑脂极压抗磨性能的改善提供可参考的基础，使其综合性能达到相对最优，从而增强聚脲润滑脂在高负荷、高速机械设备等苛刻工况下的实际使用性能。

关键词：　添加剂；　聚脲润滑脂；　性能指标；　极压抗磨性中图分类号： TQ626.4 文献标志码：A doi：10.12422/j.issn.1672⁃6952.2024.02.002Effect of Additives on the Performance of Polyurea Lubricating GreaseLI Xiaohui1,2，ZHANG Ze1，YANG Lulu1,3，WU Weiqi4，REN Xiaochen4，MA Weihua5，LI Guangtao5（1.College of Chemistry and Chemical Engineering， Xi'an Shiyou University， Xi'an Shaanxi 710065， China；2.Shaanxi Engineering Research Center of Green Low⁃Carbon Energy Materials and Processes， Xi'an Shaanxi 710065， China；3.Xi'an Key Laboratory of Low⁃Carbon Utilization for High⁃Carbon Resources， Xi'an Shaanxi 710065， China；4.Xi'an Market New Materials Technology Co. Ltd.， Xi'an Shaanxi 710399， China；5.Xi'an Petroleum Dajiarun Industry （Group） Co. Ltd.， Xi'an Shaanxi 710003， China）Abstract:　The direct method was used to prepare polyurea lubricating grease, and the effects of several different types of additives on the extreme pressure and anti⁃wear performance for polyurea lubricating grease were investigated and studied. The results demonstrate that several types of additives have good compatibility with polyurea grease, and they have little undesirable influence on colloidal stability of polyurea grease, and they can also enhance thermal stability of polyurea grease. Moreover, the addition of additives can significantly improve the performance of extreme pressure and wear resistance for polyurea lubricating grease. And in the experiments, it was found that the composite multifunctional additive containing sulfur and phosphorus has a relatively better effect on improving the extreme pressure and wear resistance of polyurea lubricating grease. The research results can provide a reference basis for the improvement of extreme pressure and anti⁃wear property for polyurea lubricating grease, achieving a relatively optimized comprehensive performance, thereby enhancing its practical utilization performance under the harsh working conditions for high load and high speed mechanical equipment.Keywords:　Additives； Polyurea lubricating grease； Performance indicators； Extreme pressure and wear resistance自1954年聚脲润滑脂被首次开发成功以来，就以高滴点、高稳定性迅速成为高性能润滑脂的典型代表，被广泛应用于冶金、汽车轴承、航空航天等领域[1⁃4]。

第37卷第1期农业工程学报V ol.37 No.1 2021年1月Transactions of the Chinese Society of Agricultural Engineering Jan. 2021 251分层接种对猪粪厌氧干发酵产气性能及微生物群落结构的影响李丹妮1，高文萱1，张克强1，孔德望2，王思淇1，杜连柱1※（1. 农业农村部环境保护科研监测所，天津300191；2.杭州能源环境工程有限公司，杭州310020）摘要：为避免厌氧干发酵酸抑制，提高产气效率，以猪粪和玉米秸秆为发酵原料，采用中温批式试验，在总固体（Total Solid, TS）为20%、接种比为25%的条件下研究分层接种和混合接种对猪粪干发酵厌氧消化性能的影响。

结果表明：2种接种方式下的发酵体系内挥发性脂肪酸（V olatile Fatty Acids,VFAs）均发生明显积累，其中，分层接种在第15天的TVFAs 质量浓度达到33.0 mg/g，之后明显降低，至发酵结束时VFAs消耗殆尽。

混合接种从第15天至发酵结束，TVFAs质量浓度维持在29.2～38.5 mg/g高水平范围内。

分层接种的累积挥发性固体甲烷产率为211.5 mL/g。

高通量测序结果显示，氢营养型产甲烷途径在2种接种方式下均占主导，但分层接种增加了发酵体系中微生物的丰富度和多样性，且群落结构更加稳定。

进一步分析表明，乙酸和pH值是影响厌氧干发酵中微生态结构的主要环境因子。

该研究结果为解除畜禽养殖废弃物酸抑制、提高产气效率提供理论依据与有益借鉴。

关键词：发酵；粪；微生物群落；分层接种；混合接种doi：10.11975/j.issn.1002-6819.2021.01.030中图分类号：X705 文献标志码：A 文章编号：1002-6819(2021)-01-0251-08李丹妮，高文萱，张克强，等. 分层接种对猪粪厌氧干发酵产气性能及微生物群落结构的影响[J]. 农业工程学报，2021，37(1)：251-258. doi：10.11975/j.issn.1002-6819.2021.01.030 Li Danni, Gao Wenxuan, Zhang Keqiang, et al. Influences of layer inoculation on biogas production and microbial community in solid-state anaerobic fermentation of pig manure[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2021, 37(1): 251-258. (in Chinese with English abstract) doi：10.11975/j.issn.1002-6819.2021.01.030 0 引 言近年来，中国的沼气产业发展迅速，已经成为最大的生物质能源产业之一[1]，随着畜禽养殖向集约化、规模化发展方式转变，沼气发酵成为消纳养殖废弃物应用最广泛的有效措施之一[2]。

专利名称：Lubricants, lubricant additives, and methods for lubricating sump- lubricated fuel-injected alcohol-powered internalcombustion engines发明人：William B. Chamberlin, III申请号：US08/156047申请日：19931123公开号：US05422022A公开日：19950606专利内容由知识产权出版社提供摘要：Lubricant compositions are disclosed which comprise (A) at least one neutral or basic metal salt of at least one acidic organic compound, wherein the metal in the salt is magnesium, barium or a mixture thereof, and (B) optionally at least one hydrocarbyl-substituted ashless dispersant in which each hydrocarbyl substituent has a number average molecular weight up to about 1500, provided that the compositions contain no more than 0.06 weight percent calcium, not more than 0.5 weight- percent hydrocarbyl-substituted ashless dispersant in which a hydrocarbyl substituent has a number average molecular weight greater than about 1, 500, and optionally not more than 0.5 weight-percent of polymeric viscosity improvers such as olefin copolymer, styrene-diene, and/or polymethacrylate viscosity improvers. Additive concentrate formulations for making such lubricant formulations are also disclosed. Methods for lubricating sump-lubricated fuel-injected alcohol-powered internal combustion engines are described which utilize these lubricant compositions to help prevent the formation of deposits in fuel injectors and provide advantageous rust and corrosion inhibition properties. These formulations canalso be useful for lubricating combustion engines powered by petroleum- and coal-derived fuels.申请人：THE LUBRIZOL CORPORATION代理人：David M. Shold,Frederick D. Hunter更多信息请下载全文后查看。