Factors affecting electrode-gel-skin interface impedance in electrical impedance tomography
食品中亚硝酸盐检测关键影响因素探究
食品中亚硝酸盐检测关键影响因素探究王强立（厦门市食品药品质量检验研究院，福建厦门 361013）摘 要：目的：运用《食品安全国家标准食品中亚硝酸盐与硝酸盐的测定》（GB 5009.33—2016）第二法分光光度法对食品中亚硝酸盐进行检测，分析影响检测结果的关键因素。
方法：将标准溶液和待测溶液在同等条件下进行测定，扩展标准曲线线性范围，将检测过程分为4个步骤，分别进行加标回收试验，结合氧化还原反应标准电极电势分析影响检测结果的关键因素。
结果：亚铁氰化钾溶液久置后可能分解产生Fe3+，Fe3+可氧化亚硝酸根导致检测结果偏低，其他溶液相对稳定。
结论：GB 5009.33—2016中分光光度法稳定可靠，亚铁氰化钾溶液的稳定性是影响检测结果的关键因素。
关键词：食品；亚硝酸盐；亚铁氰化钾；分光光度法Research on Key Influencing Factors of Determination ofNitrite in FoodsWANG Qiangli(Xiamen Institute for Food and Drug Quality Control, Xiamen 361013, China) Abstract: Objective: To detect nitrite in food by GB 5009.33—2016 second method spectrophotometry, and analyze the key factors affecting the test results. Method: The standard solution and the solution to be tested were measured under the same conditions, and the linear range of the standard curve was expanded. The detection process was divided into four steps, and the standard recovery test was carried out respectively. Combined with the standard electrode potential of the redox reaction, the key factors affecting the detection results were analyzed. Result: The potassium ferrocyanide solution may decompose to produce Fe3+ after a long time. Fe3+ can oxidize nitrite, resulting in low detection results, and other solutions are relatively stable. Conclusion: The spectrophotometric method in GB 5009.33—2016 is stable and reliable, and the stability of potassium ferrocyanide solution is the key factor affecting the test results.Keywords: food; nitrite; potassium ferrocyanide; spectrophotometry亚硝酸盐主要以钠盐和钾盐的形式存在于食品中，食品中的亚硝酸盐主要来源于人工添加和食品本身。
电催化综述
电催化的应用和存在问题1引言电催化法是使电极、电解质界面上的电荷转移加速从而加快电极反应的方法。
电催化技术涉及到的催化剂的选择至关重要，要加速电极反应，必须选用合适的电极材料，所选用的电极材料在通电过程中具有催化剂的作用，从而改变电极反应速率或反应方向，而其本身并不发生质的变化。
现在随着世界各国现代工业的迅猛发展,能源的需求量也随之急剧增加,但二十世纪末以来，我们却面临着燃料煤炭,化石能源日益枯竭，新能源的开发缓慢、能源费用上涨等各种挑战,因而节约有限能源、降低工业生产中的能耗是当务之急。
电化学科学的研究恰好适应了这种要求,电化学科学是以研究如何加速电极上电催化反应速度。
降低电极电位为研究内容,与节能降耗密切相关,特别是在强电流电解过程中的节能,采用电催化电极更是起了巨大的作用。
1电催化技术主要应用于有机污水的电催化处理；含铬废水的电催化降解；烟；二氧化碳的电解还原等。
道气及原料煤的电解脱硫；电催化同时脱除NOx和S02目前对能源利用、燃料电池和某些化学反应（如丙烯腈二聚、分子氧还原）的电催化作用研究得较深入，今后在开拓精细有机合成方面可能会得到较大的进展，特别是对那些与电子得失有关的氧化还原反应。
本文从污水的电催化处理、电催化活化碳的氧化物、电催化法脱硫脱硝、电催化与燃料电池四个大的方面介绍电催化技术的发展及研究应用现状，以及今后研究的发展趋势。
2污水的电催化处理电化学水处理技术2,3因其具有多功能性、高度的灵活性、易于自动化、无二次污染等其它水处理技术无法比拟的优点,正成为国内外水处理技术研究的热点课题,尤其对那些难于生化降解、对人类健康危害极大“三致”致癌、致畸、致突变有机污染物的去除具有很高的效率,并且又能节省大量的能源。
因而，电化学水处理技术近年来已成为世界水处理技术相当活跃的研究领域,受到国内外的广泛关注。
4相比传统的生物废水处理方法，电催化废水处理技术有更潜在的应用前景。
在比如电催化还原技术是现阶段水处理技术领域的研究热点之一，可将废水中高毒性污染物通过选择性电催化还原转化为低毒性的污染物，对含硝基苯5、氯酚6等的废水取得了良好的处理效果，具有药剂用量少、操作简易、污染物降解选择性强等优点。
ASTM D257-99
D1These test methods are under the jurisdiction of ASTM Committee D-9on Electrical and Electronic Insulating Materials and are the direct responsibility of Subcommittee D09.12on Electrical Tests.Current edition approved Oct.10,1999.Published November1999.Originally published as D257–st previous edition D257–93(1998).2Annual Book of ASTM Standards,V ol10.01.3Annual Book of ASTM Standards,V ol08.01.4Annual Book of ASTM Standards,V ol10.03.5Annual Book of ASTM Standards,V ol10.02.6Annual Book of ASTM Standards,V ol11.03. 1Copyright©ASTM,100Barr Harbor Drive,West Conshohocken,PA19428-2959,United States.conductance to that obtained if the electrodes had formed the opposite sides of a square.3.1.4.1Discussion—Surface conductivity is expressed in siemens.It is popularly expressed as siemens/square(the size of the square is immaterial).Surface conductivity is the reciprocal of surface resistivity.3.1.5conductivity,volume,n—the volume conductance multiplied by that ratio of specimen volume dimensions (distance between electrodes divided by the cross-sectional area of the electrodes)which transforms the measured conduc-tance to that conductance obtained if the electrodes had formed the opposite sides of a unit cube.3.1.5.1Discussion—V olume conductivity is usually ex-pressed in siemens/centimetre or in siemens/metre and is the reciprocal of volume resistivity.3.1.6moderately conductive,adj—describes a solid mate-rial having a volume resistivity between1and10000000 V-cm.3.1.7resistance,insulation,(R i),n—the ratio of the dc voltage applied to two electrodes(on or in a specimen)to the total volume and surface current between them.3.1.7.1Discussion—Insulation resistance is the reciprocal of insulation conductance.3.1.8resistance,surface,(R s),n—the ratio of the dc voltage applied to two electrodes(on the surface of a specimen)to the current between them.3.1.8.1Discussion—(Some volume resistance is unavoid-ably included in the actual measurement.)Surface resistance is the reciprocal of surface conductance.3.1.9resistance,volume,(R v),n—the ratio of the dc voltage applied to two electrodes(on or in a specimen)to the current in the volume of the specimen between the electrodes.3.1.9.1Discussion—V olume resistance is the reciprocal of volume conductance.3.1.10resistivity,surface,(r s),n—the surface resistance multiplied by that ratio of specimen surface dimensions(width of electrodes defining the current path divided by the distance between electrodes)which transforms the measured resistance to that obtained if the electrodes had formed the opposite sides of a square.3.1.10.1Discussion—Surface resistivity is expressed in ohms.It is popularly expressed also as ohms/square(the size of the square is immaterial).Surface resistivity is the reciprocal of surface conductivity.3.1.11resistivity,volume,(r v),n—the volume resistance multiplied by that ratio of specimen volume dimensions (cross-sectional area of the specimen between the electrodes divided by the distance between electrodes)which transforms the measured resistance to that resistance obtained if the electrodes had formed the opposite sides of a unit cube.3.1.11.1Discussion—Volume resistivity is usually ex-pressed in ohm-centimetres(preferred)or in ohm-metres. V olume resistivity is the reciprocal of volume conductivity.4.Summary of Test Methods4.1The resistance or conductance of a material specimen or of a capacitor is determined from a measurement of current or of voltage drop under specified conditions.By using the appropriate electrode systems,surface and volume resistance or conductance may be measured separately.The resistivity or conductivity can then be calculated when the required speci-men and electrode dimensions are known.5.Significance and Use5.1Insulating materials are used to isolate components of an electrical system from each other and from ground,as well as to provide mechanical support for the components.For this purpose,it is generally desirable to have the insulation resis-tance as high as possible,consistent with acceptable mechani-cal,chemical,and heat-resisting properties.Since insulation resistance or conductance combines both volume and surface resistance or conductance,its measured value is most useful when the test specimen and electrodes have the same form as is required in actual use.Surface resistance or conductance changes rapidly with humidity,while volume resistance or conductance changes slowly although thefinal change may eventually be greater.5.2Resistivity or conductivity may be used to predict, indirectly,the low-frequency dielectric breakdown and dissi-pation factor properties of some materials.Resistivity or contivity is often used as an indirect measure of moisture content,degree of cure,mechanical continuity,and deteriora-tion of various types.The usefulness of these indirect measure-ments is dependent on the degree of correlation established by supporting theoretical or experimental investigations.A de-crease of surface resistance may result either in an increase of the dielectric breakdown voltage because the electricfield intensity is reduced,or a decrease of the dielectric breakdown voltage because the area under stress is increased.5.3All the dielectric resistances or conductances depend on the length of time of electrification and on the value of applied voltage(in addition to the usual environmental variables). These must be known to make the measured value of resistance or conductance meaningful.5.4V olume resistivity or conductivity can be used as an aid in designing an insulator for a specific application.The change of resistivity or conductivity with temperature and humidity may be great(1,2,3,4),7and must be known when designing for operating conditions.V olume resistivity or conductivity determinations are often used in checking the uniformity of an insulating material,either with regard to processing or to detect conductive impurities that affect the quality of the material and that may not be readily detectable by other methods.5.5V olume resistivities above1021V·cm(1019V·m),ob-tained on specimens under usual laboratory conditions,are of doubtful validity,considering the limitations of commonly used measuring equipment.5.6Surface resistance or conductance cannot be measured accurately,only approximated,because some degree of volume resistance or conductance is always involved in the measure-ment.The measured value is also affected by the surface contamination.Surface contamination,and its rate of accumu-lation,is affected by many factors including electrostatic charging and interfacial tension.These,in turn,may affect the7The boldface numbers in parentheses refer to the list of references appended to these testmethods.surface resistivity.Surface resistivity or conductivity can be considered to be related to material properties when contami-nation is involved but is not a material property in the usual sense.6.Electrode Systems6.1The electrodes for insulating materials should be of a material that is readily applied,allows intimate contact with the specimen surface,and introduces no appreciable error because of electrode resistance or contamination of the specimen (5).The electrode material should be corrosion-resistant under the conditions of test.For tests of fabricated specimens such as feed-through bushings,cables,etc.,the electrodes employed are a part of the specimen or its mounting.Measurements of insulation resistance or conductance,then,include the contami-nating effects of electrode or mounting materials and are generally related to the performance of the specimen in actual use.6.1.1Binding-Post and Taper-Pin Electrodes ,Fig.1and Fig.2,provide a means of applying voltage to rigid insulating materials to permit an evaluation of their resistive or conduc-tive properties.These electrodes simulate to some degree the actual conditions of use,such as binding posts on instrument panels and terminal strips.In the case of laminated insulating materials having high-resin-content surfaces,somewhat lower insulation resistance values may be obtained with taper-pin than with binding posts,due to more intimate contact with the body of the insulating material.Resistance or conductance values obtained are highly influenced by the individual contact between each pin and the dielectric material,the surface roughness of the pins,and the smoothness of the hole in the dielectric material.Reproducibility of results on different specimens is difficult to obtain.6.1.2Metal Bars in the arrangement of Fig.3were prima-rily devised to evaluate the insulation resistance or conduc-tance of flexible tapes and thin,solid specimens as a fairly simple and convenient means of electrical quality control.This arrangement is somewhat more satisfactory for obtaining approximate values of surface resistance or conductance when the width of the insulating material is much greater than its thickness.6.1.3Silver Paint ,Fig.4,Fig.5,and Fig.6,is available commercially with a high conductivity,either air-drying or low-temperature-baking varieties,which are sufficiently po-rous to permit diffusion of moisture through them and thereby allow the test specimen to be conditioned after the application of the electrodes.This is a particularly useful feature in studying resistance-humidity effects,as well as change with temperature.However,before conductive paint is used as an electrode material,it should be established that the solvent in the paint does not attack the material so as to changeitsFIG.1Binding-Post Electrodes for Flat,SolidSpecimensFIG.2Taper-PinElectrodesFIG.3Strip Electrodes for Tapes and Flat,SolidSpecimenselectrical properties.Reasonably smooth edges of guard elec-trodes may be obtained with a fine-bristle brush.However,for circular electrodes,sharper edges can be obtained by the use of a ruling compass and silver paint for drawing the outline circles of the electrodes and filling in the enclosed areas by brush.A narrow strip of masking tape may be used,provided the pressure-sensitive adhesive used does not contaminate thesurface of the specimen.Clamp-on masks also may be used if the electrode paint is sprayed on.6.1.4Sprayed Metal ,Fig.4,Fig.5,and Fig.6,may be used if satisfactory adhesion to the test specimen can be obtained.Thin sprayed electrodes may have certain advantages in that they are ready for use as soon as applied.They may be sufficiently porous to allow the specimen to be conditioned,but this should be verified.Narrow strips of masking tape or clamp-on masks must be used to produce a gap between the guarded and the guard electrodes.The tape shall be such as not to contaminate the gap surface.6.1.5Evaporated Metal may be used under the same con-ditions given in 6.1.4.6.1.6Metal Foil ,Fig.4,may be applied to specimen surfaces as electrodes.The usual thickness of metal foil used for resistance or conductance studies of dielectrics ranges from 6to 80µm.Lead or tin foil is in most common use,and is usually attached to the test specimen by a minimum quantity of petrolatum,silicone grease,oil,or other suitable material,as an adhesive.Such electrodes shall be applied under a smoothing pressure sufficient to eliminate all wrinkles,and to work excess adhesive toward the edge of the foil where it can be wiped off with a cleansing tissue.One very effective method is to use a hard narrow roller (10to 15mm wide),and to roll outward on the surface until no visible imprint can be made on the foil with the roller.This technique can be used satisfactorily only on specimens that have very flat surfaces.With care,the adhesive film can be reduced to 2.5µm.As this film is in series with the specimen,it will always cause the measured resistance to be too high.This error may become excessive for the lower-resistivity specimens of thickness less than 250µm.Also the hard roller can force sharp particles into or through thin films (50µm).Foil electrodes are not porous and will not allow the test specimen to condition after the electrodes have been applied.The adhesive may lose its effectiveness at elevated temperatures necessitating the use of flat metal back-up plates under pressure.It is possible,with the aid of a suitable cutting device,to cut a proper width strip from one electrode to form a guarded and guard electrode.Such a three-terminal specimen normally cannot be used for surface resistance or conductance measurements because of the grease remaining on the gap surface.It may be very difficult to clean the entire gap surface without disturbing the adjacent edges of the electrode.6.1.7Colloidal Graphite ,Fig.4,dispersed in water or other suitable vehicle,may be brushed on nonporous,sheet insulat-ing materials to form an air-drying electrode.Masking tapes or clamp-on masks may be used (6.1.4).This electrode material is recommended only if all of the following conditions are met:6.1.7.1The material to be tested must accept a graphite coating that will not flake before testing,6.1.7.2The material being tested must not absorb water readily,and6.1.7.3Conditioning must be in a dry atmosphere (Proce-dure B,Methods D 618),and measurements made in this same atmosphere.6.1.8Mercury or other liquid metal electrodes give satisfac-tory results.Mercury is not recommended for continuous use or at elevated temperatures due to toxic effects.(Warning—Volume Resistivity g |Ls 2t Surface ResistivityFIG.4Flat Specimen for Measuring Volume and SurfaceResistances orConductancesD 05(D 1+D 2)/2L >4t g |La 2t Volume Resistivity g |Ls 2t Surface ResistivityFIG.5Tubular Specimen for Measuring Volume and SurfaceResistances orConductancesMercury metal vapor poisoning has long been recognized as a hazard in industry.The maximum exposure limits are set by the American Conference of Governmental Industrial Hygienists.8The concentration of mercury vapor over spills from broken thermometers,barometers,or other instruments using mercury can easily exceed these exposure limits.Mercury,being a liquid and quite heavy,will disintegrate into small droplets and seep into cracks and crevices in the floor.The use of a commercially available emergency spill kit is recommended whenever a spill occurs.The increased area of exposure adds significantly to the mercury vapor concentration in air.Mer-cury vapor concentration is easily monitored using commer-cially available sniffers.Spot checks should be made periodi-cally around operations where mercury is exposed to the atmosphere.Thorough checks should be made after spills.)The metal forming the upper electrodes should be confined by stainless steel rings,each of which should have its lower rim reduced to a sharp edge by beveling on the side away from the liquid metal.Fig.7A and Fig.7B show two electrode arrange-ments.6.1.9Flat Metal Plates ,Fig.4,(preferably guarded)may be used for testing flexible and compressible materials,both at room temperature and at elevated temperatures.They may be circular or rectangular (for tapes).To ensure intimate contact with the specimen,considerable pressure is usually required.Pressures of 140to 700kPa have been found satisfactory (see material specifications).6.1.9.1A variation of flat metal plate electrode systems is found in certain cell designs used to measure greases or filling compounds.Such cells are preassembled and the material to betested is either added to the cell between fixed electrodes or the electrodes are forced into the material to a predetermined electrode spacing.Because the configuration of the electrodes in these cells is such that the effective electrode area and the distance between them is difficult to measure,each cell constant,K ,(equivalent to the A/t factor from Table 1)can be derived from the following equation:K 53.6p C 511.3C(1)8American Conference of Governmental and Industrial Hygienists,6500Glen-way Ave.,Building D-7,Cincinnati,OH,45211.FIG.6Conducting-PaintElectrodesN OTE 1—Warning:See 6.1.8FIG.7Mercury Electrodes for Flat,SolidSpecimenswhere:K has units of centimetres,andC has units of picofarads and is the capacitance of the electrode system withair as the dielectric.See Test Methods D 150for methods of measurement for C.6.1.10Conducting Rubber has been used as electrode ma-terial,as in Fig.4,and has the advantage that it can quickly and easily be applied and removed from the specimen.As the electrodes are applied only during the time of measurement,they do not interfere with the conditioning of the specimen.The conductive-rubber material must be backed by proper plates and be soft enough so that effective contact with the specimen is obtained when a reasonable pressure is applied.N OTE 1—There is evidence that values of conductivity obtained using conductive-rubber electrodes are always smaller (20to 70%)than values obtained with tinfoil electrodes (6).When only order-of-magnitude accuracies are required,and these contact errors can be neglected,a properly designed set of conductive-rubber electrodes can provide a rapid means for making conductivity and resistivity determinations.6.1.11Water is widely employed as one electrode in testing insulation on wires and cables.Both ends of the specimen must be out of the water and of such length that leakage along the insulation is negligible.Guard rings may be necessary at each end.It may be desirable to add a small amount of sodium chloride to the water to ensure high conductivity.Measure-ments may be performed at temperatures up to about 100°C.7.Choice of Apparatus and Test Method7.1Power Supply —A source of very steady direct voltage is required (see X1.7.3).Batteries or other stable direct voltage supplies may be used.7.2Guard Circuit —Whether measuring resistance of an insulating material with two electrodes (no guard)or with athree-terminal system (two electrodes plus guard),consider how the electrical connections are made between the test instrument and the test sample.If the test specimen is at some distance from the test instrument,or the test specimen is tested under humid conditions,or if a relatively high (1010to 1015ohms)specimen resistance is expected,spurious resistance paths can easily exist between the test instrument and test specimen.A guard circuit is necessary to minimize interference from these spurious paths (see also X1.9).7.2.1With Guard Electrode —Use coaxial cable,with the core lead to the guarded electrode and the shield to the guard electrode,to make adequate guarded connections between the test equipment and test specimen.Coaxial cable (again with the shield tied back to the guard)for the unguarded lead is not mandatory here (or in 7.2.2),although its use provides some reduction in background noise (see also Fig.8).7.2.2Without Guard Electrode —Use coaxial cable,with the core lead to one electrode and the shield terminated about 1cm from the end of the core lead (see also Fig.9).7.3Direct Measurements —The current through a specimen at a fixed voltage may be measured using any equipment that has the required sensitivity and accuracy (610%is usually adequate).Current-measuring devices available include elec-trometers,d-c amplifiers with indicating meters,and galva-nometers.Typical methods and circuits are given in Appendix X3.When the measuring device scale is calibrated to read ohms directly no calculations are required.7.4Comparison Methods —A Wheatstone-bridge circuit may be used to compare the resistance of the specimen with that of a standard resistor (see Appendix X3).7.5Precision and Bias Considerations :7.5.1General —As a guide in the choice of apparatus,the pertinent considerations are summarized in Table 2,but it is not implied that the examples enumerated are the only ones applicable.This table is not intended to indicate the limits of sensitivity and error of the various methods per se ,but rather is intended to indicate limits that are distinctly possible with modern apparatus.In any case,such limits can be achieved or exceeded only through careful selection and combination of the apparatus employed.It must be emphasized,however,that the errors considered are those of instrumentation only.Errors such as those discussed in Appendix X1are an entirely different matter.In this latter connection,the last column of Table 2lists the resistance that is shunted by the insulation resistance between the guarded electrode and the guard system for the various methods.In general,the lower such resistance,the less probability of error from undue shunting.N OTE 2—No matter what measurement method is employed,the highest precisions are achieved only with careful evaluation of all sources of error.It is possible either to set up any of these methods from the component parts,or to acquire a completely integrated apparatus.In general,the methods using high-sensitivity galvanometers require a more permanent installation than those using indicating meters or recorders.The methods using indicating devices such as voltmeters,galvanometers,d-c amplifiers,and electrometers require the minimum of manual adjustment and are easy to read but the operator is required to make the reading at a particular time.The Wheatstone bridge (Fig.X1.4)and the potentiometer method (Fig.X1.2(b ))require the undivided attention of the operatorinN OTE 1—Warning:See 6.1.8FIG.7Mercury Cell for Thin Sheet Material(continued)keeping a balance,but allow the setting at a particular time to be read at leisure.7.5.2Direct Measurements :7.5.2.1Galvanometer-Voltmeter —The maximum percent-age error in the measurement of resistance by the galvanometer-voltmeter method is the sum of the percentage errors of galvanometer indication,galvanometer readability,and voltmeter indication.As an example:a galvanometer having a sensitivity of 500pA/scale division will be deflected 25divisions with 500V applied to a resistance of 40G V (conductance of 25pS).If the deflection can be read to the nearest 0.5division,and the calibration error (including Ayrton Shunt error)is 62%of the observed value,the resultant galvanometer error will not exceed 64%.If the voltmeter has an error of 62%of full scale,this resistance can be measured with a maximum error of 66%when the voltmeter reads full scale,and 610%when it reads one-third full scale.The desirability of readings near full scale are readily apparent.7.5.2.2Voltmeter-Ammeter —The maximum percentage er-ror in the computed value is the sum of the percentage errors in the voltages,V x and V s ,and the resistance,R s .The errors in V s and R s are generally dependent more on the characteristics of the apparatus used than on the particular method.The most significant factors that determine the errors in V s are indicator errors,amplifier zero drift,and amplifier gain stability.With modern,well-designed amplifiers or electrometers,gain stabil-ity is usually not a matter of concern.With existing techniques,the zero drift of direct voltage amplifiers or electrometers cannot be eliminated but it can be made slow enough to berelatively insignificant for these measurements.The zero driftTABLE 1Calculation of Resistivity or Conductivity AType of Electrodes or SpecimenVolume Resistivity,V -cmVolume Conductivity,S/cm r v 5A t R v g v 5t A G vCircular (Fig.4)A 5p ~D 11g !24Rectangular A 5(a +g)(b +g)SquareA 5(a +g)2Tubes (Fig.5)A 5p D 0(L +g)Cablesr v 52p LR vln D 2D 1g v 5lnD 2D 12p LR vSurface Resistivity,V (per square)Surface Conductivity,S (per square)p s 5P g R sg s 5g PG sCircular (Fig.4)P 5p D 0Rectangular P 52(a +b +2g)SquareP 54(a +g)Tubes (Figs.5and 6)P 52p D 2Nomenclature:A 5the effective area of the measuring electrode forthe particular arrangement employed,P 5the effective perimeter of the guarded electrode for the particular arrangement employed,R v 5measured volume resistance in ohms,G v 5measured volume conductance in siemens,R s 5measured surface resistance in ohms,G s 5measured surface conductance in siemens,t 5average thickness of the specimen,D 0,D 1,D 2,g,L 5dimensions indicated in Figs.4and 6(see Appendix X2for correction to g ),a,b,5lengths of the sides of rectangular electrodes,and ln 5natural logarithm.AAll dimensions are in centimetres.FIG.8Connections to Guarded Electrode for Volume and Surface Resistivity Measurements (Volume Resistance hook-up shown)is virtually nonexistent for carefully designed converter-type amplifiers.Consequently,the null method of Fig.X1.2(b )is theoretically less subject to error than those methods employ-ing an indicating instrument,provided,however,that the potentiometer voltage is accurately known.The error in R s is to some extent dependent on the amplifier sensitivity.For mea-surement of a given current,the higher the amplifier sensitivity,the greater likelihood that lower valued,highly precise wire-wound standard resistors can be used.Such amplifiers can be obtained.Standard resistances of 100G V known to 62%,are available.If 10-mV input to the amplifier or electrometer gives full-scale deflection with an error not greater than 2%of full scale,with 500V applied,a resistance of 5000T V can be measured with a maximum error of 6%when the voltmeter reads full scale,and 10%when it reads 1⁄3scale.7.5.2.3Comparison-Galvanometer —The maximum per-centage error in the computed resistance or conductance is given by the sum of the percentage errors in R s ,the galvanom-eter deflections or amplifier readings,and the assumption that the current sensitivities are independent of the deflections.The latter assumption is correct to well within 62%over the useful range (above 1⁄10full-scale deflection)of a good,modern galvanometer (probably 1⁄3scale deflection for a dc current amplifier).The error in R s depends on the type of resistor used,but resistances of 1M V with a limit of error as low as 0.1%are available.With a galvanometer or d-c current amplifier having a sensitivity of 10nA for full-scale deflection,500V applied to a resistance of 5T V will produce a 1%deflection.At this voltage,with the preceding noted standard resistor,and with F s 5105,d s would be about half of full-scale deflection,with a readability error not more than 61%.If d x is approxi-mately 1⁄4of full-scale deflection,the readability error would not exceed 64%,and a resistance of the order of 200G Vcould be measured with a maximum error of 651⁄2%.7.5.2.4Voltage Rate-of-Change —The accuracy of the mea-surement is directly proportional to the accuracy of the measurement of applied voltage and time rate of change of the electrometer reading.The length of time that the electrometer switch is open and the scale used should be such that the time can be measured accurately and a full-scale reading obtained.Under these conditions,the accuracy will be comparable with that of the other methods of measuring current.7.5.2.5Comparison Bridge —When the detector has ad-equate sensitivity,the maximum percentage error in the com-puter resistance is the sum of the percentage errors in the arms,A,B,and N .With a detector sensitivity of 1mV/scale division,500V applied to the bridge,and R N 51G V ,a resistance of 1000T V will produce a detector deflection of one scale division.Assuming negligible errors in R A and R B ,with R N 51G V known to within 62%and with the bridge balanced to one detector-scale division,a resistance of 100T V can be mea-sured with a maximum error of 66%.8.Sampling8.1Refer to applicable materials specifications for sam-pling instructions.9.Test Specimens9.1Insulation Resistance or Conductance Determination :9.1.1The measurement is of greatest value when the speci-men has the form,electrodes,and mounting required in actual use.Bushings,cables,and capacitors are typical examples for which the test electrodes are a part of the specimen and its normal mounting means.9.1.2For solid materials,the test specimen may be of any practical form.The specimen forms most commonly used are flat plates,tapes,rods,and tubes.The electrode arrangements of Fig.2may be used for flat plates,rods,or rigid tubes whose inner diameter is about 20mm or more.The electrode arrangement of Fig.3may be used for strips of sheet material or for flexible tape.For rigid strip specimens the metal support may not be required.The electrode arrangements of Fig.6may be used for flat plates,rods,or parison of materials when using different electrode arrangements is frequently inconclusive and should be avoided.9.2Volume Resistance or Conductance Determination :9.2.1The test specimen may have any practical form that allows the use of a third electrode,when necessary,to guard against error from surface effects.Test specimens may be in the form of flat plates,tapes,or tubes.Fig.4and Fig.7illustrate the application and arrangement of electrodes for plate or sheet specimens.Fig.5is a diametral cross section of three elec-trodes applied to a tubular specimen,in which electrode No.1is the guarded electrode,electrode No.2is a guard electrode consisting of a ring at each end of electrode No.1,and electrode No.3is the unguarded electrode (7,8).For materials that have negligible surface leakage,the guard rings may be omitted.Convenient and generally suitable dimensions appli-cable to Fig.4in the case of test specimens that are 3mm in thickness are as follows:D 35100mm,D 2588mm,and D 1576mm,or alternatively,D 3550mm,D 2538mm,and D 1525mm.For a given sensitivity,the largerspecimenFIG.9Connections to Unguarded Electrodes for UnguardedSurfaceMeasurements。
化妆行业必备英语专业词汇
P r e s s e d p o w d e r粉饼P u r i f y清洁用Q u i c k d r y快干R e m o v e r去除、卸妆R e p a i r修保R e v i t a l i t e活化S c r u b磨砂式去角质S e n s i t i v e敏感性皮肤S h a d i n g p o w d e r修容饼S o l v e n t溶解S p o t青春痘用S u n b l o c k防晒用T o n i n g l o t i o n化妆水T r e n t m e n t修护W a s h洗W a t e r p r o o f防水-W h i t e-美白用A c n e青春痘用品A c t i v e赋活用A f t e r s u n日晒后用品A l c o h o l-f r e e无酒精A n t i-抗、防A n t i-w r i n k l e抗老防皱B a l a n c i n g平衡酸碱B l u s h e r腮红C l e a n-清洁用C om bi n a tio n混合性皮肤C o r r e c t遮瑕膏C r e a m霜D a y日间用D r y干性皮肤E s s e n c e精华液E x f o l i a t o r去角质E y e g e l眼胶E y e m a s k眼膜E y e s h a d o w眼影E y e l i n e r眼线笔、刷F a c i a l脸部用F a s t d r y快干F i r m紧肤F o a m泡沫F o u n d a t i o n粉底T o n e r化妆水G e l胶状G e n t l e温和的H y d r a-保湿用L i p c a r e护唇用L i p c o a t口红弧膜L i p s t i c k口红L o n g l a s t i n g持久性L o t i o n水、露L o o s e p o w e r蜜粉洗面奶 cleansing milk去黑头洗面奶 biologicalcleanser清洁面霜 clarifying cream眼部御妆水 eye make upremoving按摩霜 massage cream按摩油 massage oil面膜 mask冷膜 freezing mask热膜 hotting mask海藻面膜 seaweed mask颈霜restructuring compound for the neck 特效营养霜 rich nourishing cream 眼袋霜 eyelid cream 眼部嗜喱 eye gel 日霜 day cream 晚霜 night cream 眼霜 eye cream 精华素 Ampoule 中性 normal 油性 oily 干性 dry 敏感性 sensitive 紧肤 refirming 补水 moisturizing 补氧 oxygenating 补充骨胶原 collagen hyalronic 倒膜 pour mask 植物 plant 色素 pigment 酸性 acidity 碱性 alkaline 矿物质 mineral substance 蛋白质 protein 活性细胞素 energetic cell 维生素 vitamin 化妆品 cosmetic 氧化剂 oxidant 胭脂 rouge 口红 lip stick 粉饼 powder 睫毛膏 mascara 粉底霜 foundation 眼线笔eye liner pencil 眉笔eyebrow pencil 唇线笔lip pencil 唇膏lip stick 润唇膏 lip protector 颜色 colour 红色 red 桔红色（橙色） orange 玫瑰红 rose 棕色(咖啡色) brown黄色 yellow蓝色 blue肉色 yellowish pink黑色 black白色 white紫色 purple绿色 green灰色 gray粉红色 pink洗甲水 cleaner指甲油 nail polish擦光剂 polish酒精 alcohol液体 liquid眼 eye耳 ear口 mouth鼻 nose手 hand脚 foot(feet 复数)头部 head发 hair面 face皮肤 skin手碗 wrist胸部 bust唇 lip眉 eyebrow腹部 abdomen大腿 thighs小腿 calves颈部 neck奥桑蒸气机Ao Sang steamengine皮肤测试仪skinanalysisapparatus消毒箱 disinfect box健胸仪breaststrengthening apparatus减肥仪 weight reducingapparatus高震按摩仪high frequencymassage 扫斑机fleck removal apparatus 导电极棒 conduct stick 电极electrode 磨砂刷（磨刷帚）ground brush 文眉机 eyebrow-tattooing apparatus 美容仪器 beauty apparatus 电流 electric current 电压 voltage 高压 high pressure 照射 shine 温度 humidity 力度 dynamics 高温 high temperature 电疗棒 electrotherapy stick 紫外线 ultraviolet ray 手柄 hand handler 握 hold 摘 pick 防敏 anti-anaphylaxis 距离 distance 洞、孔 hole 晚宴装 evening make up for party 文眉 tattoo eyeline 文睫毛线 upper eyeline 文唇线xlip 深层皮肤护理 deep lifting 胸部护理 bust treatment 电眼睫毛 electronic eyelash 修指甲manicure 剪指甲trimx 手部护理 hand care 减肥护理diet care 腹部减肥 reduce abdomen 打耳孔 pierce ears 腿部脱毛remove leg hours 新娘妆 bridal make up 晚妆 evening make up 日妆 day make up 皮肤护理skin care结构 composition摇动、抖动 shake震荡 frequency针 needle金属metal增加increase可触摸 tangible微波 microwave液态 liquid超声波 ultrasonic wave 红外线infrared ray大 max小min开 turn on关 turn of蒸馏 distillation冷冻 freeze热量的 thermal温和的 gentle操作 operate电磁 electromagnetism稳定的 stable调节 regulate去除 removing,get rid of 协调 harmonize选择 choose粗 thick细 thin简单 easy整体 whole尖形 point椭圆形 ellipse抬起 raise部位、位置 position机器 machine冻结 freezing减少 reduce旋转 revolve美容 facial美容室Le salon美容院 beauty salon美容师beautician美容：hairdressing 美容品业者: cosmetician、cosmetologist美容师：beautician、hairdresser美容术：beauty culture/cosmetology美容院: beauty parlor美容专家:beauty-specialist化妆盒: dressing case/powder box化妆墨: kohl化妆师: dresser/ makeupgirl化妆品: cosmetic、 makeup、toiletry化妆室：powder room/ tiringroom/ toilet room化妆水：astringent （止血剂；收敛剂）化妆台：dresser化妆箱：cosmetics case化妆椅：dressing stool化妆纸：facial tissue （面巾纸）面霜，雪花膏：facial cream美容，面部按摩： facial皮肤的：cutaneous/ dermal皮肤学/皮肤病学：dermatology皮肤变白症：albinism皮肤病：dermatosis/ skindisease皮疹：tetter皮肤寄生虫：dermatozoon皮肤干燥症：xeroderma/xerodermia皮肤画纹现象：dermatographia/dermographia皮肤炎: dermatitis皮肤移植：dermatoplasty/skin grafting按摩：knead/ massage/ rubdown/ rubdown按摩师：massagist/ rubber杏仁：almond/apricot杜松子：juniper熏衣草：lavender迷迭香：rosemary百里香：thyme木贼：equisetum西洋蓍草：yarrow啤酒花：hops茴香： fennel樟脑：camphor桉油精： eucalyptol薄荷醇：menthol细胞再生素：cell-renewal蜂窝织炎：cellulitis妊娠纹：stretch mark干性皮肤：dry skin中性皮肤：normal skin油性皮肤：oily skin精油：essential oil蜂胶：propolis芦荟：aloe深层洗擦：deep scrub胶原蛋白：collagen按摩院：massage parlor眼睑：eyelid睫毛：eyelash/eyewinker睫毛膏: eye black眉毛: brow/ eyebrow/ valla眉毛粗的:beetle-browed眉形：camber粉底: foundation make-up粉底霜: foundation cream粉盒: puff box眉笔: eyebrow pencil唇膏: lipstick眼罩: blinder/ eyepatch/patch/ winker下颚: chin过敏性测验: scratch test对…过敏/患过敏症的:allergic过敏症/过敏反应：hypersensitivity 涂抹: daub/ lay on endermic: 通过[直接用于]皮肤而起作用的、(用于)皮下的, 经皮的。
电催化综述(最新整理)
电催化的应用和存在问题1引言电催化法是使电极、电解质界面上的电荷转移加速从而加快电极反应的方法。
电催化技术涉及到的催化剂的选择至关重要，要加速电极反应，必须选用合适的电极材料，所选用的电极材料在通电过程中具有催化剂的作用，从而改变电极反应速率或反应方向，而其本身并不发生质的变化。
现在随着世界各国现代工业的迅猛发展,能源的需求量也随之急剧增加,但二十世纪末以来，我们却面临着燃料煤炭,化石能源日益枯竭，新能源的开发缓慢、能源费用上涨等各种挑战,因而节约有限能源、降低工业生产中的能耗是当务之急。
电化学科学的研究恰好适应了这种要求,电化学科学是以研究如何加速电极上电催化反应速度。
降低电极电位为研究内容,与节能降耗密切相关,特别是在强电流电解过程中的节能,采用电催化电极更是起了巨大的作用。
1电催化技术主要应用于有机污水的电催化处理；含铬废水的电催化降解；烟道气及原料煤的电解脱硫；电催化同时脱除NOx和S02；二氧化碳的电解还原等。
目前对能源利用、燃料电池和某些化学反应（如丙烯腈二聚、分子氧还原）的电催化作用研究得较深入，今后在开拓精细有机合成方面可能会得到较大的进展，特别是对那些与电子得失有关的氧化还原反应。
本文从污水的电催化处理、电催化活化碳的氧化物、电催化法脱硫脱硝、电催化与燃料电池四个大的方面介绍电催化技术的发展及研究应用现状，以及今后研究的发展趋势。
2污水的电催化处理电化学水处理技术2,3因其具有多功能性、高度的灵活性、易于自动化、无二次污染等其它水处理技术无法比拟的优点,正成为国内外水处理技术研究的热点课题,尤其对那些难于生化降解、对人类健康危害极大“三致”致癌、致畸、致突变有机污染物的去除具有很高的效率,并且又能节省大量的能源。
因而，电化学水处理技术近年来已成为世界水处理技术相当活跃的研究领域,受到国内外的广泛关注。
4相比传统的生物废水处理方法，电催化废水处理技术有更潜在的应用前景。
在比如电催化还原技术是现阶段水处理技术领域的研究热点之一，可将废水中高毒性污染物通过选择性电催化还原转化为低毒性的污染物，对含硝基操作简易、苯5、氯酚6等的废水取得了良好的处理效果，具有药剂用量少、污染物降解选择性强等优点。
心肌生理特性
几个概念： 容积导体：人提除皮肤有一定的阻抗外，内部 有电解质溶液相连通，有导电性，可是是立体的。
双极体（有方向、有大小）：心脏电活动在一 次心电周期中每个瞬时有瞬时向量
心电向量环：有大小、有方向的瞬时向量随时 间变化，各瞬时向量的尖端连成心电向量环，是立 体空间的。 其形成与心脏的位置、兴奋细胞的数量、传导 方向和速度有关。 一次心动周期中分为心房向量环和心室向量环
1 . 心脏的起搏点 自律组织自律性的高低 A. 窦房结 pacemaker cell : 100次/min B . 房室交界 A-V junction : 50次/min C. 末梢浦氏纤维网: 25次/ min
Graded autorhythmicity Sinus node : 100 / min A-V junction :50 / min A-V bundle : 40 / min Purkinje fiber terminal : 25 / min
概念 期前收缩：如果在心肌的有效不应期之后。 于下一次窦性兴奋到达之前，受到人工的或来自窦房 结之外的异位兴奋刺激，可产生一次提前出前的期前 兴奋，并引起一次收缩，称为期前收缩。
代偿间歇 Compensatory Pause
Concept : the interval间隔 between the premature contraction and the next succeeding随后的 contraction is slightly稍微的 prolonged
一次兴奋过程中兴奋性的周期性变化的特点是有效 不应期持续的时间长 慢反应电位也存在有效不应期，一直持续到4期，称 为复极化后不应状态
3. 兴奋性的周期性变化与心肌收缩活动的关系
（1）心肌不发生强直性收缩
[资料]美容化妆常用英语词汇
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[资料]美容化妆常用英语词汇34.活性细胞素 energetic 77.手碗 wristcell 78.胸部 bust美容化妆常用英语词汇79.唇 lip 35.维生素 vitamin36.化妆品 cosmetic 80.眉 eyebrow37.氧化剂 oxidant 81.腹部 abdomen 1.洗面奶 cleansing milk 38.胭脂rouge 82.大腿 thighs 2.去黑头洗面奶 biological 39.口红 lip stick 83.小腿calves cleanser 40.粉饼 powder 84.颈部 neck3洁面霜 clarifying cream 41.睫毛膏 mascara 85. 奥桑蒸气机Ao Sang 4.眼部御妆水 eye make 42.粉底霜 foundation steam engine up removing 43.眼线笔eye liner pencil 86.皮肤测试仪5.按摩霜 massage cream 44.眉笔eyebrow pencil skinanalysis apparatus6.按摩油 massage oil 45.唇线笔lip pencil 87.消毒箱 disinfect box 7.面膜mask 46.唇膏lip stick 88.健胸仪breast 8.冷膜 freezing mask 47.润唇膏lip protector strengthening apparatus 9.热膜 hotting mask 48.颜色 colour 89.减肥仪 weight 10.海藻面膜 seaweed 49.红色 red reducing apparatus mask 50.桔红色(橙色) orange 90.高震按摩仪high 11.颈霜restructuring 51.玫瑰红rose frequency massage compound for the neck 52.棕色(咖啡色) brown 91. 扫斑机fleck removal 12.特效营养霜 rich 53.黄色 yellow apparatus nourishing cream 54.蓝色 blue 92.导电极棒 conduct stick 13.眼袋霜 eyelid cream 55.肉色 yellowish pink 93.电极electrode 14.眼部嗜喱 eye gel 56.黑色 black 94.磨砂刷(磨刷帚)ground 15.日霜 day cream 57.白色 white brush16.晚霜 night cream 58.紫色 purple 眉机 eyebrow-tattooing 17.眼霜eye cream 59.绿色 green apparatus 18.精华素 Ampoule 60.灰色 gray 96.美容仪器 beauty 19.中性 normal 61.粉红色 pink apparatus 20.油性 oily 62.洗甲水 cleaner 97.电流 electric current 21.干性 dry 98.电压 voltage 63.指甲油 nail polish22.敏感性 sensitive 99.高压 high pressure 64.擦光剂 polish23.紧肤 refirming 65.酒精 alcohol 100.照射 shine 24.补水moisturizing 66.液体 liquid 101.温度 humidity 25.补氧 oxygenating 67.眼eye 102.力度 dynamics 26.补充骨胶原 collagen 68.耳 ear 103.高温high temperature hyalronic 69.口 mouth 104.电疗棒 electrotherapy 27.倒膜 pour mask stick 70.鼻 nose28.植物 plant 105.紫外线 ultraviolet ray 71.手 hand29.色素 pigment 72.脚 foot(feet 复数) 106.手柄 hand handler 30.酸性acidity 73.头部 head 107.握 hold31.碱性 alkaline 108.摘 pick 74.发 hair32.矿物质 mineral 109.防敏 anti-anaphylaxis 75.面 facesubstance 76.皮肤 skin 110.距离 distance 33.蛋白质 protein111.洞、孔 hole 146.冷冻 freeze 188.适合 fit147.热量的 thermal 189.不适合 unfit 112.晚宴装 evening make148.温和的 gentle 190.可以使can make up for party113.文眉 tattoo eyeline 149.操作 operate 191.请进 come in 114.文睫毛线 upper 15电磁 electromagnetism 192.请坐sit down eyeline 151.稳定的stable 193.关门 close the door 115.文唇线xlip 152.调节 regulate 194.加add 116.深层皮肤护理 deep 153.去除 removing,get rid 195.一会momentlifting of 196.明天tomorrow 117.胸部护bust treatment 154.协调 harmonize 197.希望 hope 118.电眼睫毛 electronic 155.选择 choose 198.小心 Look out eyelash 156.粗 thick 199.左 left 119.修指甲manicure 200.右 right 157.细thin120.剪指甲trimx 201.感觉feeling 158.简单 easy121.手部护理 hand care 159.整体 whole 202.决不no means 122.减肥护理diet care 160.尖形 point 203.满意satisfaction 123.腹部减肥 reduce 204.星期一Monday 161.椭圆形 ellipseabdomen 205.星期二Tuesday 162.抬起 raise124.打耳孔 pierce ears 163.部位、位置 position 206.星期三Wednesday 125.腿部脱毛remove leg 207.星期四Thursday 164.机器 machine hours 208.星期五Friday 165.冻结 freezing126.新娘妆 bridal make 166.减少 reduce 209.星期六Saturday up 167.旋转 revolve 210.星期日Sunday 127.晚妆 evening make 168.美容 facial 211.一月January up 169.美容室Le salon 212.二月February 128.日妆 day make up 170.美容院 beauty salon 213.三月March 129.皮肤护理skin care 171.美容师beautician 214.四月April 130.结构 composition 172.先生sir 215.五月May 131.摇动、抖动 shake 172.小姐 miss 216.六月June 132.震荡 frequency 173.脱下take off 217.七月July 133.针174.外衣 coat 218.八月August needle175.手提箱suitcase 219.九月September 134. 金属metal135.增加increase 176.这边儿this way 220.十月October 136.可触摸tangible 177.各种各样kinds of 221.十一月November178.服务 service 222.十二月December 137.微波 microwave179.项链 necklace 223.周末week 138.液态 liquid139.超声波 ultrasonic 180.耳环earring 224.早安good morning wave 181.穿上put on 225.下午好good 140.红外线infrared ray 182.价钱 price afternoom 141.大 max 183.收费 charge 226.晚上好good night 142.小min 184.费用cost 227.祝你好运good luck 143.开 turn on 185.欢迎welcome 228.当然of course 144.关 turn of 186.几点 what time 229.正是Exactly 145.蒸馏distillation 187.多少How much 230.正正如此Quite so231.的确surely 269.卷发器 rollers/perm bed light/bed lamp 床头灯rollers232.很好 very good fluorescent lamp 日光灯233.真妙Excellent ceiling lamp/pendant lamp234.十分乐意with 吊灯refrigerato冰箱 automatic pleasure desk/table lamp 台灯 rice cooker 电饭锅 235.啊我明白了 oh ,I see wall light 壁灯 steamer 蒸锅 236.是真的That's true floor lamp 落地灯 oven 烤箱 237.或许不是Perhaps chandelier 枝状吊灯 grill 烧烤架 238.从来没有Nevertoaster 烤面包机 239.不要紧Don't worry water gauge 水表 egg beater打蛋器 240.不行that won't do plug 插头ice crusher 刨冰机 241.行了 that will do outlet/receptacle 插座 242.再来一次once morefood processor 食品加工243.再试一次try again paste 浆糊机 paper towel 纸巾 244.请原谅Excuse me glue 胶水apron 围裙 245.停止Stop that adhesive tape 胶条 tableware 餐具 246.为什么,what for? packing paper 包装纸 plate 盘子 247.怎么会的How can? string 绳子 dish 碟子 248.为什么不 Why not? carpenter 木工 bowl 碗 249.一点也不 Not at all electrician 电工 cupboard 碗橱 250.是这样吗,Is it so? utility man 杂务工 dining table 餐桌 251.什么时候?when? plumber 管道工larder 食品柜 252.哪一样 Which? painter 油漆工 drop-leaf table 可以折叠253.怎么样 How? vacuum hose holder 吸尘边缘的桌子 254.描眉卡brow template 器管子的托架 chopping board 案板 255.纸巾facial tissuewatering can 浇水壶 cutlery tray 装餐具的容器 256.吸油纸 oil-Absorbing dish drainer 晾干餐具的容Sheets blanket 毛毯器(类似铁丝筐) 257.化装棉cotton pads cushion 垫子 table cloth 桌布 258.口红刷lip brush quilt被子259.胭脂扫 blush brushlaundry bag 洗衣袋 260.转笔刀pencil cotton terry blanket 毛巾pail洗衣桶 sharpener 被ironing board 烫衣板 261.电动剃毛器 electric feather quilt 羽绒被steam and dry iron 蒸汽电cotton quilt 棉被 shaver-for women 熨斗 bedding 床上用品 262.电动睫毛卷electricelectric iron 电熨斗 lash curler? mosquito net 蚊帐 laundry drier 烘干机 263.粉扑 powder puffs pillow 枕头 spin-drier 旋转式脱水机 264.海绵扑 sponge puffs bolster 长枕 washing machine 洗衣机 265.眉刷brow brush pillow case 枕套 radiator 暖气片 266.睫毛夹 lash curler tick 褥子electric fan 电扇 carpet 地毯 (一般指大的267.染发 hair colorstand fan 落地电扇整块的，铺房间的那种) 268.冷烫水 perm/permingoscillating fan 摇头电扇 formula rug 地毯(一般指小块的，放在沙发等边上的那种) razor 刮胡刀 3. Don"t take it to heart.别toothpaste 牙膏家居英语单词(五 - 卧室) 往心里去，别为此而忧虑伤toothbrush 牙刷bed frame/bed base 床架神。
安美特++电镀基础知识培训
Atotech (China) Chemicals Ltd.SH 安美特上海青浦分公司PRESENTSELECTROPLATINGTRAINING电镀培训OUTLINE 内容提要♌INTRODUCTION介绍♌ELECTROCHEMISTRY 电化学♌CLEANING & PREPLATE 清洗及预镀♌NICKEL 镍♌Copper 铜♌DECORATIVE CHROMIUM 装饰铬♌TESTING测试♌FILTRATION过滤♌TROUBLE SHOOTING 故障处理WHAT IS ELECTROPLATING ?什么是电镀？THE DEPOSITION OF A METALLICCOATING UPON A NEGATIVELYCHARGED CATHODE BY THEPASSING OF AN ELECTRIC CURRENT 在电流通过时，有金属层沉积在带负电荷的阴极表面.WHAT IS THE PURPOSE ?电镀的目的是什么？♌TO OBTAIN A METALLIC COATING HAVING CERTAIN PROPERTIES SUCH AS HARDNESS, BRIGHTNESS, CORROSION RESISTANCE AND TO REPRODUCE IDENTICAL FORMS IN ELECTROFORMING.♌是为了得到具有某种特性的金属层，如：硬度、光亮度、耐腐性及在电铸方面复制同样的形状.REQUIREMENTS要求♌SOURCE OF DIRECT CURRENT直流电源♌A PLATING TANK电镀槽♌A SOLUTION CONTAINING THE DISSOLVED SALTS OF THE METAL TO BE PLATED含有待镀的可溶性金属盐的溶液♌ANODE( POSITIVE ELECTRODE )阳极（正电极）♌A PREPARED OBJECT -CATHODE ( NEGATIVE ELECTRODE )准备好的待镀工件--阴极（负电极）WHAT IS DIRECT CURRENT ?何为直流电？THE FLOW OF ELECTRONS IN THE SAME DIRECTION BETWEEN POSITIVE ANDNEGATIVE ELECTRODES在正负电极之间电子向同样的方向移动.WHAT IS A PLATING SOLUTION ?电镀液是什么？A CONDUCTING MEDIUM FOR THEMOVEMENT OF METAL IONS INSOLUTION BETWEEN AN ANODE ANDA CATHODE溶液中在阳极与阴极间金属离子移动的导电介质.WHAT IS pH ?什么是pH值？♌THE MEASUREMENT OF ACIDITY OR ALKALINITY用来度量酸碱度的♌ON A SCALE FROM 0 TO 14pH值的范围处于0-14之间♌0 TO 6.9 BEING ACIDIC AND7.1 TO 14 ALKALINE AND 7.0 BEING NEUTRAL.小于7的为酸性，大于7且小于等于14的为碱性，7.0为中性HOW ARE PLATING SOLUTION MAINTAINED ?如何维护电镀液？♌CHEMICAL ANALYSIS OF THE CONSTITUENTS持续的化学分析♌HULL CELL PLATING TESTS赫氏槽电镀测试♌ADDITION OF CHEMICALS添加化学品♌ELIMINATION OF CONTAMINANTS去除污染物♌PERIODIC PURIFICATION定期净化♌REGULAR INSPECTION OF PARTS FOR DEFECTS缺陷/次品的常规检查♌PHYSICAL TESTING物理测试WHAT IS A METAL ION ?什么是金属离子？A METAL ION IS AN ATOM OF A METAL HAVING A POSITIVE ELECTRICAL CHARGE金属离子是带正电荷的金属原子(失去电子)WHAT ARE THE SOURCES OF METAL IONS ?金属离子来自何处？♌METAL SALTS IN PLATING SOLUTION电镀液中的金属盐♌SOLUBLE METAL ANODES可溶性的金属阳极WHAT ARE ANODE BAGS ?什么是阳极袋？ANODE BAGS ARE POROUS MEMBRANES PLACED AROUND ANODES TO COLLECT SLUDGE FORMING ON THE DISSOLVING ANODE 阳极袋是包扎在阳极外面,会将电镀过程中产生的阳极泥收集在袋内的多孔的袋。
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November 1996
electrical spectroscopy, and thus increase the effectiveness and versatility of LIT systems. It can therefore be seen that the electrode contact impedance can adversely affect the accuracy of existing mono-frequency LIT systems which are operated in the tens of kHz range and the accuracy of the lower end of the frequency range of the new multi-frequency systems. Theoretically at least, it would be highly desirable to completely surround the body part under study with many closely spaced small electrodes. Decreasing electrode size will, however, increase the electrode-gel-skin impedances and thus can cause problems during LIT measurement. Large contact impedances can give rise to large potential drops at the electrode-skin interface, which may mask voltage changes within the underlying tissues. The presence of reactive contact impedances generates phase shifts which can cause misleading measurements (TAKTAK e t al., 1995b). The mismatch of contact impedances can be responsible for significant errors that result in common mode voltages in impedance imaging systems (SMITH, 1990). Gersing et aL, have shown that even impedance mismatches due to differences in the lengths of current pathways in an electrolyte tank can give rise to the appearance of positive phase angles (GERSINGe t al., 1995) Contact impedance can also be a source of noise (GONDRAN et al., 1995) and drift (BAISCHet al., 1995), and it has been shown that these may cause artefacts in LIT measurements (BOONEand HOLDER,1995a;b). In the two-electrode technique, the contact impedances of both electrodes are measured along with the desired tissue impedance. The two-electrode technique is therefore very susceptible to problems due to the magnitude, mismatch or drift of contact impedances. In a four-electrode technique, the voltmeters do not measure electrode contact impedances, and hence should be insensitive to problems arising from electrode contact. Although the four-electrode technique is less sensitive to contact impedance problems, problems still do arise. Riu et al.; showed theoretically that large mismatches in the resistive and/or capacitive properties of the voltage detection electrodes, in particular, can result in errors in both the real and reactive parts of the measured impedance (RIu et aL, 1995). The contact impedances in the current injection circuit develop a common-mode voltage on the body, while those in the voltage measuring circuit reduce its common-mode rejection ratio (CMRR) and thus prevent the elimination of the common-mode voltage (BOONE and HOLDER, 1995b). It is interesting to note that, as the contact impedances form part of a larger overall circuit which is complicated by the presence of stray capitances etc., the effects due to contact impedance
f
Review
Factors affecting electrode-gel-skin interface impedance in electrical impedance tomography
E. T. M c A d a m s I J. Josher z
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! Importance of electrode-gel-skin contact
~LECTRICALimpedance tomography (EIT) is the production of mages of the distribution of electrical impedance, or more :ommonly resistivity, in a two-dimensional slice through a ~ody segment by means of impedance measurements made on :he surface of the body part under study. The impedance is ?rooed with a series of two- or four-electrode measurements asing an array of electrodes attached to the skin and encircling :he area of interest. A reconstruction algorithm then computes -he electrical conductivity or permittivity distribution within :he body slice using the applied current waveforms and the aaeasured voltages. In a two-electrode measurement, the same electrode pair is ased to applied the current and to measure the resultant voltage. In a four-electrode measurement, current is applied ay a pair of electrodes and the voltage is measured using a .different pair of electrodes located elsewhere on the body mrface. A four-electrode technique is used in most EIT ~ystems. For example, in the Sheffield Mark 1 EIT system, ~r is the most often used for clinical trials, current is applied sequentially to the body segment using a pair of tdjacent electrodes (BARBER et al., 1983). While current is acing applied to a given pair of electrodes, the voltages aetween the adjacent pairs of the remaining non-current "arrying electrodes are measured. This process is repeated for each pair of adjacent electrodes, and a complete set of voltage data is thus obtained.