专业英语文献翻译
Quantifying the Cluster of Differentiation 4 Receptor Density on Human T Lymphocytes Using Multiple Reaction Monitoring Mass Spectrometry. ABSTRACT: Cluster of differentiation 4 (CD4) is an important glycoprotein containing four extracellular domains, a transmembrane portion and a short intracellular tail. It locates on the surface of various types of immune cells and performs a critical role in multiple cellular functions such as signal amplification and activation of T cells. It is well-known as a clinical cell surface protein marker for study of HIV progression and for defining the T helper cell population in immunological applications. Moreover, CD4 protein has been used as a biological calibrator for quantification of other surface and intracellular proteins. However, flow cytometry, the conventional method of quantification of the CD4 density on the T cell surface depends on antibodies and has suffered from variables such as antibody clones, the ommatophore and conjugation chemistries, the fixation conditions, and the flow cytometric quantification methods used. In this study, we report the development of a highly reproducible na no liquid chromatography?multiple reaction monitoring mass spectrometry-based quantitative method to quantify the CD4 receptor density in units of copy number per cell on human CD4+ T cells. The method utilizes stable isotope-labeled full-length standard CD4 as an internal standard to measure endogenous CD4 directly, without the use of antibodies. The development of the mass spectrometry-based approach of CD4 protein quantification is important as a complementary strategy to validate the analysis from the cytometry-based conventional method. It also provides new support for quantitative understanding and advanced characterization of CD4 on CD4+ T cells.
Cluster of differentiation 4 (CD4) is a glycoprotein that locates on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells. As a co receptor, CD4 amplifies the signal generated by the T cell receptor, which is essential for activation of many molecules involved in the signaling cascade of an activated T cell. In human T lymphocytes, CD4 receptor protein is encoded by the CD4 gene1and has four distinct extracellular domains (D1 to D4), a transmembrane portion, and a short intracellular tail.2The use of antihuman CD4 monoclonal antibodies generated against the four extracellular domains has been widely used to define T helper cells in phenotypical. Although the number of CD4+ T cells decreases in the progression of HIV-1 viral infection deriving from the gp120 viral protein binding to the CD4 receptor, Ponce let et al. reported that the surface CD4 density still
remained constant on T helper cells of HIV-1 infected individuals.3Since then, multiyear research has supported the theory that CD4 expression/density can be used as a biological calibrator for quantification of other surface
and intracellular proteins.4
Quantitative multicolor flow cytometry incorporating anti- bodies and a fluorescence detection method has played a critical role in clinical diagnostics and immunotherapies. Though the ultimate objective of quantitative flow cytometry is to measure the number of antigens or ligand binding sites associated with a cell, the task is carried out by measuring the number of antibodies bound per cell (ABC). It is critically important to produce biological cell reference materials that bear well-characterized protein markers such as CD4 for the trans-formation of a calibrated linear fluorescence intensity scale of a flow cytometer channel to a biologically meaningful ABC scale.7The quality of the cytometric measurements is affected by variables such as antibody clones, the ommatophore and conjugation chemistries, the fixation conditions, and the flow cytometric quantification methods used.4,8?11Hence, in addition to characterizing candidate reference cell preparations that use antibody-based cytometric methods,12it is necessary to develop a complementary approach to validate the absolute quantification of reference marker proteins such as CD4 without the use of antibodies.
Liquid chromatography coupled mass spectrometry has emerged as a versatile platform for quantitative protein/proteges analysis due to its high specificity and sensitivity. Relative quantification of proteins can be achieved without the use of any internal standard for comparative analysis under the same catalytical conditions. However, in many analyses such as clinical biomarker tests, absolute quantification of protein(s) in terms of molecule copy number per cell or per unit weight/volume of biological samples is required.Absolute quantitative data enable valuable comparisons across different studies and conclusive interpretations of the disease states or treatment efficacy as well as the understanding of the whole body system biology probed from different angles in different studies. Multiple reaction monitoring mass spectrometry (MRM MS) combining proper separation and/or fractionation techniques has been proven to be an effective platform for protein quantification in biological samples.16?18In the present study, we report the development of an MRM MS-based approach that combines scalepan liquid chromatography and a stable isotope-labeled full-length protein as the internal standard, enabling the quantification
of the CD4 receptor density in units of copy number per cell on human CD4+ T cells without the use of antibodies.
EXPERIMENTAL SECTION
Materials. All chemicals and reagents, unless indicated specifically, were from Sigma-Ald rich Inc.
Determination of the Human CD4+ T Cell Count.Cryopreserved, negatively selected human CD4+ T cells with a purity of 98.5% were purchased from Astarte Biologics (Redmond, WA), confirmed internally, and used without further purification. The thawed cryopreserved CD4+ T cells were slowly added to 9 L of RPMI-1640 containing 10% fetal bovine serum (FBS) in a 15 L conical tube. After the tube was inverted three times, the cells were centrifuged at 400gnfor 10 min, and the supernatant was discarded. The resulting cells were washed once and re suspended in phosphate-buffered saline (PBS) with 1% FBS. The number of CD4+ T cells was counted by using both a hemocytometer and a flow cytometry with which Count beads from BD Bioscience (San Jose,CA) were used as the internal counting standard. Mouse antihuman CD4 fluorescein isocyanate (FITC; clone SK3,catalog number 340133, BD Biosciences) was used for cell staining, and CD4+ cells were counted using an Aria II flow sorter from BD Biosciences. Gating of CD4+ and Count beads was performed on a FITC histogram. The ratio of the respectively gated events of CD4+ cells and Count beads was used for obtaining the CD4+ cell number according to the manufacturer’s procedure. The CD4+ cell numbers measured by the hemocytometer and flow cytometry were fairly consistent with a difference of no more than 6%, and therefore, the averaged cell count from both methods was used to derive the CD4 receptor density/copy number per cell.
Characterization of Isotope-Labeled Standard CD4.Isotope label (13C and15N) was introduced on arginine and lysine residues in a standard CD4 protein from Orig ene Technologies (Rockville, MD). The amino acid sequence of this standard CD4 protein is provided in the Supporting Information, Table S1. Since the isotope incorporation of the standard protein is not 100%, the percentage of isotope labeling
was evaluated using MRM MS by comparing the chroma to-graphic peak intensities of transitions from the isotope-labeled peptides to the peak intensities of the corresponding transitions from the unlabeled peptides. The concentration of the isotope-labeled internal standard CD4 was then determined using a recombinant CD4 protein (rCD4) (obtained from the NIH AIDS Research & Reference Reagent
Program) with a known concentration. The rCD4 purity was determined to be above 96% using sodium dodecastyle sulfate?polyacrylamide gel electro-phoresis
(SDS?PAGE), and the concentration was calculated t o be 31.84 μmol/L by amino acid analysis determined from averaging the concentrations of seven amino acid residuals,Spartacist acid, glutamine acid, glycine, alanine, leucine, lysine, and arginine, using Standard Reference Material (SRM) 2389 of the National Institute of Standards and Technology (NIST)(amino acids in 0.1 mol/L Cl) as the amino acid calibration standard on an amino acid analyzer from Hitachi Instruments(Dallas, TX). Sample Preparation for MRM MS. A preparation procedure of human CD4+ T cells for MRM MS measure- aments is illustrated in Figure 1. The isotope-labeled
full-length standard CD4 of known concentration was mixed with a known number of human T cells in 150 μL of 25 Mold/L ammonium bicarbonate buffer (Abb), pH 7.9, with 2% SDS. The cell and protein mixture was lysed by sonication on ice at 20 W using three 10 s continuous cycles (Diatonically 3000 from Miso,Farmingdale, NY). The mixture was treated with 20 Mold/LDTT and incubated at room temperature for 60 min to allow reduction of cysteines and was then treated with 50 Mold/L acetamid for another 60 min for alkylation. The cell lysate was centrifuged at 175000gnfor 30 min to remove insoluble fragments. Proteins in the supernatant were precipitated using chloroform/methanol19,20to remove salts and lipids. Briefly, 1volume of sample solution was combined with 4 volumes of methanol, 1 volume of chloroform, and 3 volumes of water. The solution was mixed by vortex and centrifuged at
20000gnat room temperature for 10 min. The upper phase was removed carefully, and 4 volumes of methanol was added to the lower phase and interphase, which contained precipitated proteins. The mixed solution was centrifuged again at 20000gn for 10 min to pellet the protein. The precipitated protein mixture was then reconstituted in 100 μL of 25 Mold/L Abb followed by protease digestion using trypsin (sequence grade modified, Pr omega, 1:50 w/w trypsin/protein) overnight at 37°C. After enzymatic digestion, the sample was treated with 0.5%fluorometric acid and centrifuged at 175000gnfor 30 min. The supernatant, which contained soluble peptides, was transferred to a fresh centrifuge's tube and dried by vacuum centrifugation (Elmendorf AG, Hamburg, Germany) for subsequent mass spectrometry analysis.
Fano-LC?MRM MS Analys is. The digested peptides were reconstituted in Dilli-Q
H2O with 3% acetonitrile (ACN) containing 0.1% formic acid followed by
Kano-LC?MRM MS analysis. Peptide separation and mass spectrometry analysis were performed on a hybrid triple-quadrupole/linear ion trap mass spectrometer (4000 QTRAP, ABI/MDS-SCIEX) coupled to an Intransigent canola-2D system (Dublin, CA). Peptides were separated and eluted at a flow rate of 300 nL/min over 30 min with a gradient of acetonitrile from 15% to 35% in H2O containing 0.1% formic acid using an Intransigent Chipley-flexional system equipped with a Kano Chipley column, 15cm × 75 μm, packed with Reposal-Pur C18-AQ, 3 μm (Dr.Ischuria, Germany). The eluted peptides were directed into the mass spectrometer with a pranayama source. The subsequent MRM detection of CD4 signature peptides was performed in the positive ion mode with the following key parameters: ion spray voltage of 2200 V, curtain gas pressure of 15 psi, source gas pressure of 20 psi, interface heating temperature of 170 °C,
blustering potentials of 76 V for +2 precursor ions and 65 V for +3 precursor ions, collision cell exit potentials of 16 V for +2 precursor ions and 13 V for +3 precursor ions, and dwell time of 40 ms for each transition pair. The collision energy of each target transition was optimized empirically using peptides from unlabeled rCD4 and isotope-labeled standard CD4. The peptides detected and optimized collision energy (CE) values are listed in the Supporting Information, Table S2. The mass spectrometer was operated using Analyst 1.5.1 (AB SCIEN).Since the detectable ions of different peptides from a single protein can be different in different mass spectrometers, we selected and optimized the target CD4 peptides from human T cells and working MS parameters using our MRM analysis for the standard proteins based on favorable transition peak intensities, stable retention times, and minimum biological matrix effects. Considering the complexity of the cell lysate, the similarity of the intensity ratios of multiple transitions from the selected peptides from standard CD4 and the counterpart in the cell lysate confirmed minimal interference from the biological matrix. Each selected peptide was further confirmed as a unique CD4 peptide by sequence blast against the human nonredundant genome database (NCBI).
Data Analysis. Calibration curves showed linearity and low scatter over the range of 0.1?5 mol/μL tested for the internal standard. The concentration of the stable
isotope-labeled standard CD4, Miso, was calculated according to the following equation:
Isopodan Ir refer to the intensity of the isotope-labeled peptide peak and intensity of the rCD4 peptide peak, respectively. In?ISO corresponds to the intensity of the total
non-isotope-labeled peptide peak detected, and the constant 0.23 is the ratio of the non labeled to the labeled peptide obtained from the internal standard CD4. Aris the concentration (mol/L) of rCD4 derived from the amino acid analysis. The endogenous CD4 protein concentration, Bend, was derived in the same fashion from the ratio of the non labeled and labeled MRM transition peak intensities multiplied by the known amount of standard spiked into the sample on the basis of the following equation: Bedstands for the intensity of the endogenous CD4 peptide peak.The identities of the selected peptides were confirmed on the basis of the two parameters of the internal standard run under the same conditions, the retention time of the given peptide,and the proportional ratio among the MRM transitions. Each pair of transitions from a given peptide was treated as an independent measure for the peptide, resulting in a concentration value expressed as the copy number of the
quantified peptide per cell. Analysis of each selected signature peptide was based on the mean value of multiple transitions from the peptide. Three signature peptides were employed to evaluate the endogenous CD4 concentration. Each sample was measured in triplicate, and a total of three cell lysate replicates were prepared and measured independently.
RESULTS AND DISCUSSION
Concentration and Isotope Incorporation Efficiency of Stable Isotope-Labeled Standard CD4. With the Kano-LC?MRM MS approach, we applied the stable isotope-labeled internal standard CD4 for quantification of the endogenous CD4 receptor protein from human CD4+ T cells. Therefore,the isotope incorporation and the concentration of the internal standard CD4 protein are key factors for accurate quantification of endogenous CD4 on T cells in the MRM MS-based quantification scheme and were carefully investigated in the present study using mass spectrometry. We measured the isotope incorporation efficiency in the standard CD4 using MRM MS based on the intensity ratio of the natural isotope abundance peptide to the stable isotope-labeled peptide within the standard protein sample. The selected peptides and the isotope incorporation percentage are listed in Table 1. Each individual peptide was analyzed by at least three transitions, and the isotope incorporation percentage of each peptide was the average value of multiple transitions.The average isotope incorporation of the standard CD4 is 81.6±0.7% based on four peptides per multiple-replicate experiment. The ratio of non labeled to labeled protein was
calculated to be 0.23 and used for calculations of the endogenous CD4 density.
By comparing the peak intensity ratio of the targeted peptides of the stable isotope-labeled standard CD4 and rCD4 with a known concentration, the concentration of the heavily labeled standard CD4 is calculated to be 0.22 ±0.03 μmol/L according to eq 1 (Table 2). Six peptides and at least three transitions per peptide were employed to determine the concentration of the isotope-labeled standard protein. These 6 peptides contain 61 amino acids and cover 13.3% of the full-length CD4, ranging across the extracellular portion of the protein (Supporting Information, Table S1). This experiment was repeated three times. The mean value of all the peptides measured was taken as the concentration of the isotope-labeled internal standard CD4.
Quantification of Endogenous CD4 Receptor on the Surface of Human T Cells. The target peptides employed for CD4 quantification were selected on the basis of favorable transition intensities and minimum matrix effects from our empirical data. Representative ion chromatograms of selected transitions from the signature peptides are shown in Figure 2.Each peptide was evaluated using no less than three pairs of transitions. The comparable intensity ratios of the transition pairs from the different peptides indicated that the unique target CD4 protein was measured. The CD4 quantification in our study was performed with a total of three replications from different cell lysates for statistical purposes. The protein density per copy number on the surface of the CD4+ T cell was derived from the mean values of all selected signature peptides according to eq 2. The results of endogenous CD4 quantification are summarized in Table 3. On the basis of our data, the copy number of CD4 protein receptors on a human CD4+ T cell varies from 1.43 × 10^5to 1.50 × 10^5with a mean of 1.46 ×105. The results are larger than those obtained using the conventional flow-cytometry-based method (～(0.90?1.10) × 105measured), which relies on the affinity binding between CD4 receptors and anti-CD4 antibodies.
In normal resting human helper T cells, CD4 glycoproteins controlled by the encoding gene are exclusively distributed on the cell surface.1,2Down-modulated CD4 cell surface expression and subcellular localization21and depletion of the surface CD4 protein22have been reported in the literature in the case of HIV infection. For the present study, purified CD4+helper T cells were obtained from a normal blood donor tested for blood-borne pathogens HIV-1 and -2, hepatitis B, Hepatica, and HTLV-1. Hence, endoplasmic CD4 proteins are expected to be negligible. With the method
described, we avoided using an antibody-based affinity assay as it is used in the conventional cytometry approach. Thus, the variations resulting from the antibody clone and binding specificity and fluorescent label specific issues do not interfere with our CD4 measurement. Moreover, the antibody-based approach only measures protein quantity through recognition of a single protein epitope. The association of CD4 receptor with lipid rafts23could affect the affinity binding by the anti-CD4 antibody, resulting in a lower detectable CD4 density. The quantification by the MRM MS approach was based on multiple unique peptides of CD4, providing more quantitative information on the full length of the protein. It would be of particular interest for CD4 analysis in cells in different biological conditions since various protein functions are usually associated with unknown cleavages and modifications. We did not detect any membrane-associated and cytoplasmic CD4 peptides in this study due to the limitation of the peptide length and detection sensitivity. Additional effort will be taken to resolve both the intracellular portion and membrane-associated portion of CD4 in a future study.
CONCLUSIONS
We reported the development of a Kano-LC?MRM MS-based quantitative method to quantify the CD4 density on a human CD4+ T cell. The full-length stable isotope-labeled CD4 served
as the internal standard for the quantification of the CD4 receptor density on a human CD4+ T cell based on the MRM transition intensity ratio of selected peptides. Application of isotope-labeled full-length proteins as internal standards overcomes potential quantitative errors from protein hydrolysis and variations associated with complex biological sample processing such as sample fractionation. This MRM MS-based method is relatively simple to implement with less variation compared to other available approaches. The quantification method in our study showed great reproducibility with low standard deviations. The method can be applied for quantification of other cell marker proteins.It would be of great interest to examine the limit of detection of this method on Proterozoic biomarkers with diverse expression levels. As demonstrated in this study, MRM MS is a powerful tool for biomolecule quantification and can potentially assist the biomolecular analysis in clinical laboratories.
摘要：集群分化4(CD4)是一种重要的糖蛋白，它包含四个胞外区域,横跨膜的部分和短的细胞内尾巴。它位于各种类型免疫细胞的表面，在多种细胞功能中扮演重要角色，像细胞信号放大和激活的T细胞。众所周知的是作为研究艾滋病病程的临床细胞表面蛋白标记和在免疫学应用程序中定义辅助T细胞数量。除此之外，CD4细胞蛋白质也已被用作其他表面和胞内蛋白量化的生物校准器。但是，流式细胞，传统量化CD4 T细胞表面密度的方法取决于抗体和并且会受到像抗体克隆、荧光团和结合化学、固定条件以及以前流式细胞定量方法等变量带来的改变。在这项研究中，我们报道一种人类CD4 + T细胞中量化CD4受体密度在每个细胞的拷贝数的高度可再生的纳米液相色谱- 多反应监测质谱为基础的定量方法的发展。该方法利用稳定同位素标记的全长标准CD4作为内部标准来直接衡量内源性CD4，而不需要使用抗体。以CD4质谱为基础的蛋白定量方法的发展，作为一个重要的补充战略来验证分析以流式细胞仪为基础的传统方法。它还提供了定量的理解和CD4在CD4 + T细胞上高级鉴定的新支持。
Heavy Oil Development Technology of Liaohe Oilfield Han Yun (Scientific Research Information Department Exploration&Development Research Institute，Liaohe Oilfield Company) Liaohe Oilfield，the largest heavy oil production base in China，features in various reservoir types，deep burial，and wide range of crude oil viscosity．For many years，a series of technologies have been developed for different oil products and reservoir types of the oilfield，of which water flooding，foam slug drive，steam stimulation，steam drive,and SAGD are the main technologies. After continuous improvement，they have been further developed and played an important role in the development of heavy oil in the oilfield． Liaohe Oilfield is abundant in heavy oil resources，46％of the total proved reserves of Liaohe Oilfield Company. Horizontally the resources concentrates in the West Depression and the southern plunging belt of the Central Uplift in Liaohe Rift. Vertically,it is mainly distributed in Paleocene Shahejie Formation(ES). The distinctive geological feature of Liaohe 0ilfield is manifested in three aspects：first，the heavy oil reservoirs are deeply buried and 80％of them are buried more than 900m deep；second，the heavy oil viscosity ranges widely．For most of the reservoirs．the dead oil viscosity ranges in 100～100000mPa·s with the maximum 650000mPa·s.Third the reservoir types are various with complicated oil—water relationship，most of the reservoirs are edge water and bosom water reservoirs and there are also edge water reservoirs，top water reservoirs and bosom water reservoirs．For more than 20 years of development，Liaohe Oilfield has developed series of heavy oil development technologies for different oil products and different types of reservoirs，such as water flooding, foam slug drive,steam stimulation steam drive and SAGD．The most difficult issues have been overcome in the development of the super
01 THE ELEMENTS AND THE PERIODIC TABLE 01 元素和元素周期表 The number of protons in the nucleus of an atom is referred to as the atomic number, or proton number, Z. The number of electrons in an electrically neutral atom is also equal to the atomic number, Z. The total mass of an atom is determined very nearly by the total number of protons and neutrons in its nucleus. This total is called the mass number, A. The number of neutrons in an atom, the neutron number, is given by the quantity A-Z. 质子的数量在一个原子的核被称为原子序数,或质子数、周淑金、电子的数量在一个电中性原子也等于原子序数松山机场的总质量的原子做出很近的总数的质子和中子在它的核心。这个总数被称为大量胡逸舟、中子的数量在一个原子,中子数,给出了a - z的数量。 The term element refers to, a pure substance with atoms all of a single kind. T o the chemist the "kind" of atom is specified by its atomic number, since this is the property that determines its chemical behavior. At present all the atoms from Z = 1 to Z = 107 are known; there are 107 chemical elements. Each chemical element has been given a name and a distinctive symbol. For most elements the symbol is simply the abbreviated form of the English name consisting of one or two letters, for example: 这个术语是指元素,一个纯物质与原子组成一个单一的善良。在药房“客气”原子的原子数来确定它,因为它的性质是决定其化学行为。目前所有原子和Z = 1 a到Z = 107是知道的;有107种化学元素。每一种化学元素起了一个名字和独特的象征。对于大多数元素都仅仅是一个象征的英文名称缩写形式,一个或两个字母组成,例如: oxygen==O nitrogen == N neon==Ne magnesium == Mg
Lesson 1 力学的基本概念 1、词汇： statics [st?tiks] 静力学；dynamics动力学；constraint约束；magnetic [m?ɡ＇netik]有磁性的；external [eks＇t?:nl] 外面的, 外部的；meshing啮合；follower从动件；magnitude [＇m?ɡnitju:d] 大小；intensity强度，应力；non-coincident [k?u＇insid?nt]不重合；parallel [＇p?r?lel]平行；intuitive 直观的；substance物质；proportional [pr?＇p?:??n?l]比例的；resist抵抗，对抗；celestial [si＇lestj?l]天空的；product乘积；particle质点；elastic [i＇l?stik]弹性；deformed变形的；strain拉力；uniform全都相同的；velocity[vi＇l?siti]速度；scalar[＇skeil?]标量；vector[＇vekt?]矢量；displacement代替；momentum [m?u＇ment?m]动量； 2、词组 make up of由……组成；if not要不，不然；even through即使，纵然； Lesson 2 力和力的作用效果 1、词汇： machine 机器；mechanism机构；movable活动的；given 规定的，给定的，已知的；perform执行；application 施用；produce引起，导致；stress压力；applied施加的；individual单独的；muscular [＇m?skjul?]]力臂；gravity[ɡr?vti]重力；stretch伸展，拉紧，延伸；tensile[tensail]拉力；tension张力，拉力；squeeze挤；compressive 有压力的，压缩的；torsional扭转的；torque转矩；twist扭，转动；molecule [m likju:l]分子的；slide滑动; 滑行；slip滑，溜；one another 互相；shear剪切；independently独立地，自立地；beam梁；compress压；revolve (使)旋转；exert [iɡ＇z?:t]用力，尽力，运用，发挥，施加；principle原则, 原理，准则，规范；spin使…旋转；screw螺丝钉；thread螺纹； 2、词组 a number of 许多；deal with 涉及，处理；result from由什么引起；prevent from阻止，防止；tends to 朝某个方向；in combination结合；fly apart飞散； 3、译文： 任何机器或机构的研究表明每一种机构都是由许多可动的零件组成。这些零件从规定的运动转变到期望的运动。另一方面，这些机器完成工作。当由施力引起的运动时，机器就开始工作了。所以，力和机器的研究涉及在一个物体上的力和力的作用效果。 力是推力或者拉力。力的作用效果要么是改变物体的形状或者运动，要么阻止其他的力发生改变。每一种
Unit 1 Chemical Industry 化学工业 1.Origins of the Chemical Industry Although the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolution, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860s with the exploitation of William Henry Perkin‘s discovery if the first synthetic dyestuff—mauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75% of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under conditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world warⅠin 1914. This initiated profound changes which continued during the inter-war years (1918-1939). 1．化学工业的起源 尽管化学品的使用可以追溯到古代文明时代，我们所谓的现代化学工业的发展却是非常近代（才开始的）。可以认为它起源于工业革命其间，大约在1800年，并发展成为为其它工业部门提供化学原料的产业。比如制肥皂所用的碱，棉布生产所用的漂白粉，玻璃制造业所用的硅及Na2CO3. 我们会注意到所有这些都是无机物。有机化学工业的开始是在十九世纪六十年代以William Henry Perkin 发现第一种合成染料—苯胺紫并加以开发利用为标志的。20世纪初，德国花费大量资金用于实用化学方面的重点研究，到1914年，德国的化学工业在世界化学产品市场上占有75%的份额。这要归因于新染料的发现以及硫酸的接触法生产和氨的哈伯生产工艺的发展。而后者需要较大的技术突破使得化学反应第一次可以在非常高的压力条件下进行。这方面所取得的成绩对德国很有帮助。特别是由于1914年第一次世界大仗的爆发，对以氮为基础的化合物的需求飞速增长。这种深刻的改变一直持续到战后（1918-1939）。 date bake to/from: 回溯到 dated: 过时的，陈旧的 stand sb. in good stead: 对。。。很有帮助
第二章科技英语构词法 词是构成句子的要素，对词意理解的好坏直接关系到翻译的质量。 所谓构词法即词的构成方法，即词在结构上的规律。科技英语构词特点是外来语多（很多来自希腊语和拉丁语）；第二个特点是构词方法多，除了非科技英语中常用的三种构词法—转化、派生及合成法外，还普遍采用压缩法、混成法、符号法和字母象形法。 2.1转化法（Conversion） 由一种词类转化成另一种词类，叫转化法。例如： water(n.水)→water(v.浇水) charge(n.电荷) →charge(v.充电) yield(n.产率) →yield(v.生成) dry(a.干的) →dry（v.烘干） slow(a.慢的) →slow(v.减慢) back(ad.在后、向后) →back（v.使后退、倒车） square(n.正方形) →square(a.正方形的) 2.2派生法（Derivation） 通过加前、后缀构成一新词。派生法是化工类科技英语中最常用的构词法。 例如“烷烃”就是用前缀（如拉丁或希腊前缀）表示分子中碳原子数再加上“-ane”作词尾构成的。若将词尾变成“-ane”、“-yne”、“-ol”、“-al”、“-yl”，则分别表示“烯”、“炔”、“醇”、“醛”、“基”、等。依此类推，从而构成千成种化学物质名词。常遇到这样的情况，许多化学化工名词在字典上查不到，全若掌握这种构词法，能过其前、后缀分别代表的意思，合在一起即是该词的意义。下面通过表1举例说明。需要注意的是，表中物质的数目词头除前四个另有名称外，其它均为表上的数目词头。 本书附录为化学化工专业常用词根及前后缀。此外还可参阅《英汉化学化工词汇》（第三版）附录中的“英汉对照有机基名表”、“西文化学名词中常用的数止词头”及“英汉对照有机词尾表”。 据估计，知道一个前缀可帮助人们认识450个英语单词。一名科技工作者至少要知道近50个前缀和30个后缀。这对扩大科技词汇量，增强自由阅读能力，提高翻译质量和加快翻译速度都是大有裨益的。 2．3合成法（Composition） 由两个或更多的词合成一个词，叫合成法。有时需加连字符。 如副词+过去分词well-known 著名的 名词+名词carbon steel 碳钢 rust-resistance 防锈 名词+过去分词computer-oriented 研制计算机的 介词+名词by-product 副产物 动词+副词makeup 化妆品 check-up 检查 形容词+名词atomic weight 原子量 periodic table 周期表 动词+代词+副词pick-me-up 兴奋剂 副词+介词+名词out-of-door 户外 2．4压缩法（Shortening） (1)只取词头字母 这种方法在科技英语中较常用。
Foreign material： Chemical Industry 1.Origins of the Chemical Industry Although the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolution, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860s with the exploitation of William Henry Perkin’s discovery if the first synthetic dyestuff—mauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75% of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under conditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world warⅠin 1914. This initiated profound changes which continued during the inter-war years (1918-1939). Since 1940 the chemical industry has grown at a remarkable rate, although this has slowed significantly in recent years. The lion’s share of this growth has been in the organic chemicals sector due to the development and growth of the petrochemicals area since 1950s. The explosives growth in petrochemicals in the 1960s and 1970s was largely due to the enormous increase in demand for synthetic polymers such as polyethylene, polypropylene, nylon, polyesters and epoxy resins. The chemical industry today is a very diverse sector of manufacturing industry, within which it plays a central role. It makes thousands of different chemicals which
1.2 总线互连 总线是连接两个或多个设备的通信通路。总线的关键特征是，它是一条共享传输介质。多个设备连接到总线上，任一个设备发出的信号可以为其他所有连接到总线上的设备所接收。如果两个设备同时传送，它们的信号将会重叠，引起混淆。因此，一次只能有一个设备成功地（利用总线）发送数据。 典型的情况是，总线由多条通信通路或线路组成，每条线(路)能够传送代表二进制1和0的信号。一段时间里，一条线能传送一串二进制数字。总线的几条线放在一起能同时并行传送二进制数字。例如, 一个8位的数据能在8条总线线上传送。 计算机系统包含有多种不同的总线，它们在计算机系统层次结构的各个层次提供部件之间的通路。连接主要计算机部件(处理机, 存储器, I/O)的总线称为系统总线。系统总线通常由50~100条分立的(导)线组成。每条线被赋予一个特定的含义或功能。虽然有许多不同的总线设计，但任何总线上的线都可以分成三个功能组：数据线、地址线和控制线。此外可能还有为连接的模块提供电源的电源线。 数据线提供系统模块间传送数据的路径，这些线组合在一起称为数据总线。典型的数据总线包含8、16或32根线，线的数量称为数据总线的宽度。因为每条线每次传送1位，所以线的数目决定了每次能同时传送多少位。数据总线的宽度是决定系统总体性能的关键因素。 地址线用于指定数据总线上数据的来源和去向。例如，如果处理机希望从存储器中读一个字的数据，它将所需要字的地址放在地址线上。显然，地址总线的宽度决定了系统最大可能的存储器容量。 控制线用来控制对数据线和地址线的访问和使用。由于数据线和地址线被所有部件共享，因此必须用一种方法来控制它们的使用。控制信号在系统模块之间传送命令和定时信息。定时信息指定了数据和地址信息的有效性，命令信号指定了要执行的操作。 大多数计算机系统使用多总线，这些总线通常设计成层次结构。图1.3显示了一个典型的高性能体系结构。一条局部总线把处理机连接到高速缓存控制器，而高速缓存控制器又连接到支持主存储器的系统总线上。高速缓存控制器集成到连接高速总线的桥中。这一总线支持连接到：高速LAN、视频和图形工作站控制器，以及包括SCSI 和FireWire的局部外设总线的接口控制器。低速设备仍然由分开的扩充总线支持，用一个接口来缓冲该扩充总线和高速总线之间的通信流量。 PCI 外部设备互连是流行的高带宽的、独立于处理机的总线，它能够作为中间层或外围设备总线。当前的标准允许在66MHz频率下使用多达64根数据线，其原始传输速率为528MB/s, 或4.224Gbps。PCI被设计成支持各种各样基于微处理机的配置，包括单处理机和多处理机的系统。因此，它提供了一组通用的功能。PCI使用同步时序以及集中式仲裁方案。 在多处理机系统中，一个或多个PCI配置可通过桥接器连接到处理机的系统总线上。系统总线只支持处理机/高速缓存单元、主存储器以及PCI桥接器。使用桥接器使得PCI独立于处理机速度，又提供快速接收和传送数据的能力。 2.1 光存储介质：高密度存储器 2.1.1 光盘 光盘技术最终可能使磁盘和磁带存储淘汰。用这种技术，磁存储器所用的读/写头被两束激光代替。一束激光通过在光盘上刻制微小的凹点，对记录表面进行写；而另一束激光用来从光敏感的记录表面读取数据。由于光束容易被偏转到光盘上所需要的位置，所以不需要存取臂。 对用户而言，光盘正成为最有吸引力的选择。它们(光盘)对环境变化不太敏感，并且它们以每兆字节比磁盘低得多的存储器价格提供更多的直接存取存储器。光盘技术仍在出现，并且还需要稳定；然而，目前有三种主要类型的光盘。它们是CD-ROM、WORM盘和磁光盘。 CD-ROM 1980年引入的，非常成功的CD，或紧密盘是设计来提高音乐的录音重放质量的光盘。为了制作一张CD，把音乐的模拟声音转换成等价的数字声音，并且存储在一张4.72英寸的光盘上。在每张光盘上可以用数字格式（用20亿数字位）记录74分钟的音乐。因为它的巨大存储容量，计算机工业的企业家们立刻认
实验方法 辐射黑色体理论（Chao et al., 1961）和切削表面理论（Friedman and Lenz, 1970）。随着敏感的红外感光胶片的发展，在一个可被记录切削侧面温度场的工具（Boothroyd, 1961）和电视型红外线敏感的视频设备已被哈里斯等人使用（1980年），以热传感和半导体量子吸收的原则为基础的红外线传感器的不断发展，使得这些传感器的第二敏感性大于第一次，其时间常数很小太- 在微秒到毫秒的范围之内。图5.21显示了最新使用的第二类的例子。有两个传感器以及开始投入使用，一个是在1毫米至5毫米的波长范围的敏感型锑化铟，另外一个是从6毫米至13毫米的敏感型碲镉汞类型，通过与两个不同的探测器信号比较可以使用温度测量更敏感的方法。大部分金属切削温度已进行了调查和了解使得更好地了解这个过程。原则上，温度测量可能用于条件监测，例如，警告说如果是天气太热导致切割刀具后刀面磨损，然而，尤其是辐射能尺寸，在生产条件，校准问题以及确保辐射能量途径从伤口区到探测器不被打断的困难，使得以温度测量为目的方法不够可靠切削的另一种方式是监测声发射，这虽然是一个间接的方法，但研究过程的状态是一个值得考虑未来。 5.4 声发射 材料的活跃形变—例如裂缝的增长，变形夹杂物，快速塑性剪切，甚至晶界，位错运动都是伴随着弹性应力波的排放而产生。这就是声发射（AE）。排放的发
生在一个很宽的频率范围内，但通常是从10万赫到1兆赫。虽然波幅度很小，但是他们可以被检测到，通过强烈的压电材料如钛酸钡或压电陶瓷传感器制造从，（Pb（Zr x Ti1–x）O3; x = 0.5 to 0.6）。图5.22显示了传感器的结构。声波传送到压力传感器造成直接的压力E（△L/L），其中E是传感器的杨氏模量，L 是它的长度，△L是它的长度变化。应力产生电场 T = g33E(△L/L)（5.7a） g33是传感器材料的压电应力系数。传感器两端的电压是TL，然后 V= g33E△L（5.7b） g33和E的典型值分别是24.4 × 10-3Vm/ N和58.5GPa，以检测电压高达0.01毫伏，这是可能的。将这些值代入方程（5.7b）导致了检测△L的长度变化的可以小到7 × 10-15米：对于一个L = 10毫米的传感器来说，即相当于拥有7 ×10-13 图5.22显示的是声发射传感器的结构 实验理论方法
1 Unit5元素周期表 As our picture of the atom becomes more detailed 随着我们对原子的描述越来越详尽，我们发现我们陷入了进退两难之境。有超过100多中元素要处理，我们怎么能记的住所有的信息？有一种方法就是使用元素周期表。这个周期表包含元素的所有信息。它记录了元素中所含的质子数和电子数，它能让我们算出大多数元素的同位素的中子数。它甚至有各个元素原子的电子怎么排列。最神奇的是，周期表是在人们不知道原子中存在质子、中子和电子的情况下发明的。Not long after Dalton presented his model for atom( )在道尔顿提出他的原子模型（原子是是一个不可分割的粒子，其质量决定了它的身份）不久，化学家门开始根据原子的质量将原子列表。在制定像这些元素表时候，他们观察到在元素中的格局分布。例如，人们可以清楚的看到在具体间隔的元素有着相似的性质。在当时知道的大约60种元素中，第二个和第九个表现出相似的性质，第三个和第十个，第四个和第十一个等都具有相似的性质。 In 1869,Dmitri Ivanovich Mendeleev,a Russian chemist, 在1869年，Dmitri Ivanovich Mendeleev ,一个俄罗斯的化学家，发表了他的元素周期表。Mendeleev通过考虑原子重量和元素的某些特性的周期性准备了他的周期表。这些元素的排列顺序先是按原子质量的增加,,一些情况中, Mendeleev把稍微重写的元素放在轻的那个前面.他这样做只是为了同一列中的元素能具有相似的性质.例如,他把碲(原子质量为128)防在碘(原子质量为127)前面因为碲性质上和硫磺和硒相似, 而碘和氯和溴相似. Mendeleev left a number of gaps in his table.Instead of Mendeleev在他的周期表中留下了一些空白。他非但没有将那些空白看成是缺憾，反而大胆的预测还存在着仍未被发现的元素。更进一步，他甚至预测出那些一些缺失元素的性质出来。在接下来的几年里，随着新元素的发现，里面的许多空格都被填满。这些性质也和Mendeleev所预测的极为接近。这巨大创新的预计值导致了Mendeleev的周期表为人们所接受。 It is known that properties of an element depend mainly on the number of electrons in the outermost energy level of the atoms of the element. 我们现在所知道的元素的性质主要取决于元素原子最外层能量能级的电子数。钠原子最外层能量能级（第三层）有一个电子，锂原子最外层能量能级（第二层）有一个电子。钠和锂的化学性质相似。氦原子和氖原子外层能级上是满的，这两种都是惰性气体，也就是他们不容易进行化学反应。很明显，有着相同电子结构（电子分布）的元素的不仅有着相似的化学性质，而且某些结构也表现比其他元素稳定（不那么活泼） In Mendeleev’s table,the elements were arranged by atomic weights for 在Mendeleev的表中，元素大部分是按照原子数来排列的，这个排列揭示了化学性质的周期性。因为电子数决定元素的化学性质，电子数也应该（现在也确实）决定周期表的顺序。在现代的周期表中，元素是根据原子质量来排列的。记住，这个数字表示了在元素的中性原子中的质子数和电子数。现在的周期表是按照原子数的递增排列，Mendeleev的周期表是按照原子质量的递增排列，彼此平行是由于原子量的增加。只有在一些情况下（Mendeleev注释的那样）重量和顺序不符合。因为原子质量是质子和中子质量的加和，故原子量并不完全随原子序数的增加而增加。原子序数低的原子的中子数有可能比原子序数高的原
Unit 21 Chemical Industry and Environment 化学工业与环境 How can we reduce the amount of waste that is produced? And how we close the loop by redirecting spent materials and products into programs of recycling? All of these questions must be answered through careful research in the coming years as we strive to keep civilization in balance with nature. 我们怎样才能减少产生废物的数量？我们怎样才能使废弃物质和商品纳入循环使用的程序？所有这些问题必须要在未来的几年里通过仔细的研究得到解决，这样我们才能保持文明与自然的平衡。 1.Atmospheric Chemistry Coal-burning power plants, as well as some natural processes, deliver sulfur compounds to the stratosphere, where oxidation produces sulfuric acid particles that reflect away some of the incoming visible solar radiation. In the troposphere, nitrogen oxides produced by the combustion of fossil fuels combine with many organic molecules under the influence of sunlight to produce urban smog. The volatile hydrocarbon isoprene, well known as a building block of synthetic rubber, is also produced naturally in forests. And the chlorofluorocarbons, better known as CFCs, are inert in automobile air conditioners and home refrigerators but come apart under ultraviolet bombardment in the mid-stratosphere with devastating effect on the earth’s stratospheric ozone layer. The globally averaged atmospheric concentration of stratospheric ozone itself is only 3 parts in 10 million, but it has played a crucial protective role in the development of all biological life through its absorption of potentially harmful shout-wavelength solar ultraviolet radiation. 1．大气化学 燃煤发电厂像一些自然过程一样，也会释放硫化合物到大气层中，在那里氧化作用产生硫酸颗粒能反射入射进来的可见太阳辐射。在对流层，化石燃料燃烧所产生的氮氧化物在阳光的影响下与许多有机物分子结合产生都市烟雾。挥发的碳氢化合物异戊二烯，也就是众所周知的合成橡胶的结构单元，可以在森林中天然产生含氯氟烃。我们所熟悉的CFCs，在汽车空调和家用冰箱里是惰性的，但在中平流层内在紫外线的照射下回发生分解从而对地球大气臭氧层造成破坏，全球大气层中臭氧的平均浓度只有3ppm，但它对所有生命体的生长发育都起了关键的保护作用，因为是它吸收了太阳光线中有害的短波紫外辐射。 During the past 20 years, public attention has been focused on ways that mankind has caused changes in the atmosphere: acid rain, stratospheric zone depletion, greenhouse warming, and the increased oxidizing capacity of the atmosphere. We have known for generations that human activity has affected the nearby surroundings, but only gradually have we noticed such effects as acid rain on a regional then on an intercontinental scale. With the problem of ozone depletion and concerns about global warming, we have now truly entered an era of global change, but the underlying scientific facts have not yet been fully established. 在过去的二十年中，公众的注意力集中在人类对大气层的改变：酸雨、平流层臭氧空洞、温室现象，以及大气的氧化能力增强，前几代人已经知道，人类的活动会对邻近的环境造成影响，但意识到像酸雨这样的效应将由局部扩展到洲际范围则是慢慢发现的。随着臭氧空洞问题的出现，考虑到对全球的威胁，我们已真正进入到全球话改变的时代，但是基本的
第一课现代数字设计及数字信号处理 课文 A: 数字信号处理简介 1.什么是数字信号处理？ 数字信号处理，或DSP，如其名称所示，是采用数字方式对信号进行处理。在这种情况下一个信号可以代表各种不同的东西。从历史的角度来讲，信号处理起源于电子工程，信号在这里意味着在电缆或电话线或者也有可能是在无线电波中传输的电子信号。然而，更通用地说，一个信号是一个可代表任何东西--从股票价格到来自于远程传感卫星的数据的信息流。术语“digital”来源于“digit”，意思是数字（代可以用你的手指计数），因此“digital”的字面意思是“数字的，用数字表示的”，其法语是“numerique”。一个数字信号由一串数字流组成，通常（但并非一定）是二进制形式。对数字信号的处理通过数字运算来完成。 数字信号处理是一个非常有用的技术，将会形成21世纪的新的科学技术。数字信号处理已在通信、医学图像、雷达和声纳、高保真音乐产生、石油开采等很广泛的领域内引起了革命性的变革。这些领域中的每一个都使得DSP技术得到深入发展，有该领域自己的算法、数学基础，以及特殊的技术。DSP发展的广度和深度的结合使得任何个人都不可能掌握已发展出的所有的DSP技术。DSP教育包括两个任务：学习应用数字信号处理的通用原则及学习你所感兴趣的特定领域的数字信号处理技术。 2.模拟和数字信号 在很多情况下，所感兴趣的信号的初始形式是模拟电压或电流，例如由麦克风或其它转换器产生的信号。在有些情况下，例如从一个CD播放机的可读系统中输出的信号，信号本身就是数字的。在应用DSP技术之前，一个模拟信号必须转换成数字信号。例如，一个模拟电压信号，可被一个称为模数转换器或ADC 的电路变换成数字信号。该转换器产生一系列二进制数字作为数字输出，其值代表每个采样时刻的输入模数转换设备的电压值。 3.信号处理 通常信号需要以各种方式处理。例如，来自于传感器的信号可能被一些没用的电子“噪声”污染。测心电图时放在病人胸部的电极能测量到当心脏及其它肌肉活动时微小的电压变化。信号也常会被来自于电源的电磁干扰所影响。采用滤波电路处理信号至少可以去掉不需要的信号部分。如今，对信号滤波以增加信号的质量或抽取重要信息的任务越来越多地由DSP技术完成而不是采用模拟电路完成。 4.DSP的发展和应用 数字信号处理的发展起源于60年代大型数字计算机进行数字处理的应用，如使用快速傅立叶变换（FFT）可以快速计算信号的频谱。这些技术在当时并没有被广泛应用，因为通常只有在大学或者其它的科研机构才有合适的计算机。 由于当时计算机很贵，DSP仅仅局限于少量的非常重要的应用。先驱们的探索工作主要集中在4个关键领域：雷达和声纳，用于保卫国家安全；石油开采，可以赚大量的钱；空间探索，其中的数据是不能重复产生的；及医学图像，可以救治生命。 20世纪80年代到90年代个人电脑的普及使得DSP产生了很多新的应用。与以往由军方或政府的需求驱动不同，DSP突然间由商业市场的需求驱动了。任何