Low-temperature transport of correlated electrons

Designation:D746–07Standard Test Method forBrittleness Temperature of Plastics and Elastomers by Impact1This standard is issued under thefixed designation D746;the number immediately following the designation indicates the year of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1.Scope*1.1This test method covers the determination of the tem-perature at which plastics and elastomers exhibit brittle failure under specified impact conditions.Two routine inspection and acceptance procedures are also provided.N OTE1—When testing rubbers for impact brittleness use Test Methods D2137.1.2The values stated in SI units are to be regarded as the standard.1.3Due to the potential safety and environmental hazards associated with mercury-filled thermometers,the use of alter-native temperature measuring devices(such as thermocouples and RTDs)is encouraged.1.4This standard does not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.N OTE2—This test method and ISO974(E)are technically equivalent when using the Type Bfixture and the Type III specimen,however,the minimum number of specimens that are required to be tested is signifi-cantly different when using this test method.The ISO method requires thata minimum of100specimens be tested.2.Referenced Documents2.1ASTM Standards:2D618Practice for Conditioning Plastics for TestingD832Practice for Rubber Conditioning For Low Tempera-ture TestingD883Terminology Relating to PlasticsD2137Test Methods for Rubber Property—BrittlenessPoint of Flexible Polymers and Coated FabricsE1Specification for ASTM Liquid-in-Glass Thermometers E77Test Method for Inspection and Verification of Ther-mometersE608/E608M Specification for Mineral-Insulated,Metal-Sheathed Base Metal ThermocouplesE1137/E1137M Specification for Industrial Platinum Re-sistance Thermometers2.2ISO Standard:ISO974(E)Plastics—Determination of the Brittleness Temperature by Impact32.3ASTM Adjuncts:Detailed Drawing of a Typical Clamp43.Terminology3.1General—The definitions of plastics used in this test method are in accordance with Test Method D883unless otherwise specified.3.2brittleness temperature—that temperature,estimated statistically,at which50%of the specimens would probably fail.4.Summary of Test Method4.1To determine the brittleness temperature,specimens are secured to a specimen holder with a torque wrench.The specimen holder is immersed in a bath containing a heat-transfer medium that is cooled.The specimens are struck at a specified linear speed and then examined.The brittleness temperature is defined as the temperature at which50%of the specimens fail.5.Significance and Use5.1This test method establishes the temperature at which 50%of the specimens tested fail when subjected to the conditions specified herein.The test provides for the evaluation1This test method is under the jurisdiction of ASTM Committee D20on Plastics and is the direct responsibility of Subcommittee D20.30on Thermal Proper-ties.30.07).Current edition approved March1,2007.Published March2007.Originallyapproved st previous edition approved in2004as D746-04.2For referenced ASTM standards,visit the ASTM website,,or contact ASTM Customer Service at service@.For Annual Book of ASTM Standards volume information,refer to the standard’s Document Summary page on the ASTM website.3ISO Standards Handbook21,V ol 1.ISO Standards are available from American National Standards Institute(ANSI),25W.43rd St.,4th Floor,New York, NY10036.4A detailed drawing of a typical clamp may be obtained from ASTM Headquar-ters.Order Adjunct:ADJD0746.*A Summary of Changes section appears at the end of this standard. Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959,United States.of long-time effects such as crystallization,or those effects that are introduced by low-temperature incompatibility of plasticiz-ers in the material under test.Plastics and elastomers are used in many applications requiring low-temperature flexing with or without e data obtained by this method to predict the behavior of plastic and elastomeric materials at low tempera-tures only in applications in which the conditions of deforma-tion are similar to those specified in this test method.This test method has been found useful for specification purposes,but does not necessarily measure the lowest temperature at which the material is suitable for use.6.Apparatus 6.1Type A :6.1.1Specimen Clamp and Striking Member —Design the specimen clamp to hold the specimen or specimens as a cantilever beam.Each individual specimen shall be firmly and securely held in a separate clamp.The striking edge shall move relative to the specimens at a linear speed of 20006200mm/s at impact and during at least the following 6.4mm of travel.In order to maintain this speed on some instruments,it is necessary to reduce the number of specimens tested at one time.The distance between the center line of the striking edge and the clamp shall be7.8760.25mm at impact.The striking edge shall have a radius of 1.660.1mm.The striking arm and specimen clamp shall have a clearance of 6.3560.25mm at and immediately following impact.These dimensional require-ments are illustrated in Fig.1.Fig.2shows a typical clamp.4Use free-fitting clamping screws,10-32National Fine Thread.6.2Type B :6.2.1Specimen Clamp and Striking Member —Design the specimen clamp to hold the specimen or specimens as a cantilever beam.Each individual specimen shall be firmly and securely held in a separate clamp.The striking edge shall move relative to the specimens at a linear speed of 20006200mm/s at impact and during at least the following 5.0mm of travel.In order to maintain this speed on some instruments,it is necessary to reduce the number of specimens tested at one time.The radius of the lower jaw of the clamp shall be 4.060.1mm.The striking edge shall have a radius of 1.660.1mm.The striking edge and specimen clamp shall have a clearance of 3.660.1mm at and immediately follow-ing impact.The clearance between the outside of the striking edge and the clamp shall be 2.060.1mm at impact.These dimensional requirements of the striking edge and clamping device are illustrated in Fig.3.Fig.4shows a typical clamp.Details of the specimen clamp are given in Fig.5.6.3Torque Wrench,0to 8.5N ·m.N OTE 3—Because of the difference in geometry of the specimen clamps,test results obtained when using the Type A specimen clamp and striking member may not correlate with those results obtained when using the Type B apparatus.6.4Temperature-Measurement System —The temperature of the heat-transfer medium shall be determined with a tempera-ture measuring device (for example,thermocouple,resistance thermometer,or liquid-in-glass thermometer)having a suitable range for the temperatures at which the determinations are to be made.The temperature-measuring device and the related readout equipment shall be accurate to at least 60.5°C.The temperature-measuring device shall be located as close to the specimens as possible.Thermocouples shall conform to the requirements of Specification E 608/E 608M .Resistance tem-perature devices shall comply with the requirements of Speci-fication E 1137/E 1137M .Liquid-in-glass thermometers,are described in Specification E e the thermometer appropri-ate for the temperature range and accuracy required,and calibrate it for the appropriate immersion depth in accordance with Test Method E 77.6.5Heat-Transfer Medium —Use any liquid heat transfer medium that remains fluid at the test temperature and does not appreciably affect the material being tested.Measurement of selected physical properties prior to and after 15-min exposure at the highest temperature used will provide an indication of the inertness of a plastic to the heat transfer medium.6.5.1Where a flammable or toxic solvent is used as the cooling medium,follow customary precautions when handling such materials.Methanol is the recommended heat transfer medium for rubber.N OTE 4—The following materials have been found suitable for use at the indicated temperatures.When silicone oil is used,moisture from the air will condense on the surface of the oil,causing slush to form.If slush collects on the temperature-measuring device as ice,it will affect temperature measurement.When this occurs,remove the ice from the temperature-measuring device.MaterialTemperature,°C5-mm 2/s viscosity silicone oil −602-mm 2/s viscosity silicone oil −76Methyl alcohol−906.6Temperature Control —Suitable means (automatic or manual)shall be provided for controlling the temperature of the heat-transfer medium to within 60.5°C of the desired value.Powdered solid carbon dioxide (dry ice)and liquid nitrogen are recommended for lowering the temperature,and an electric immersion heater for raising the temperature.6.7Tank,insulated.6.8Stirrer,to provide thorough circulation of the heat transfer medium.N OTE 5—Suitable apparatus is commercially available from several suppliers.The striking member may be motor-driven,solenoid-operated,FIG.1Dimensional Requirements Between Specimen Clamp andStriking Edge (TypeA)gravity-actuated,or spring-loaded.Equip the motor-driven tester with a safety interlock to prevent striker arm motion when the cover is open.7.Test Specimen7.1Type I (for Fixture Type A):7.1.1Geometry —This type of specimen shall be 6.3560.51mm wide by 31.7566.35mm long as illustrated in Fig.6.7.1.2Preparation —Specimens shall be 1.9160.13mm thick.Specimens shall be die-punched,cut by hand using a razor blade or other sharp tool,or cut by an automatic machine from flat sheet,or prepared by injection molding.7.2Type II (for Fixture Type A):7.2.1Geometry (Modified T-50Specimen)—This type of specimen shall be T-shaped,as illustrated in Fig.6.When using this type of specimen,clamp it so that the entire tab is inside the jaws for a minimum distance of 3.18mm.7.2.2Preparation —Specimens shall be 1.9160.13mm thick.Specimens shall be die-punched,cut by hand using a razor blade or other sharp tool,or cut by an automatic machine from flat sheet,or prepared by injection molding.7.3Type III (for Fixture Type B):7.3.1Geometry —This type of specimen shall be 20.060.25mm long by 2.560.05mm wide and 1.660.1mm thick as illustrated in Fig.6.7.3.2Preparation —Specimens shall be die-punched,cut by hand using a razor blade or other sharp tool,or cut by an automatic machine from flat sheet,or prepared by injection molding.7.4Test results will vary according to molding conditions and methods of specimen preparation.It is essential that preparation methods produce uniform specimens.The pre-ferred method of preparation is to use an automatic cutting machine,however specimens that are punched using an arbor press or hydraulically operated press are also acceptable.No matter which preparation method is employed,the specimen edges shall be free of all flash.Specimens that are damaged in any way shall be discarded.If specimens are to be die punched,sharp dies must be used in the preparation of specimens for this test if reliable results are to be achieved.Careful maintenance of die cutting edges is of extreme importance and is obtained by daily lightly honing and touching up the cutting edges with jewelers’hard Arkansas honing stones.The condition of the die is judged by investigating the rupture point on any series of broken specimens.When broken specimens are removed from the clamps of the testing machine it is advantageous to pile these specimens and note if there is any tendency to break atorFIG.2Typical Clamp (TypeA)N OTE —Dimensions are in millimetres.FIG.3Dimensional Details of Striking Edge and Clamping Device,Type B (Positioning of Unnotched TestSpecimen)FIG.4Assembled Clamp with Test Specimens,TypeBnear the same portion of each specimen.Rupture points consistently at the same place are the indication that the die is dull,nicked,or bent at that particular position,or that some other defect ispresent.N OTE —Dimensions are in millimetres.FIG.5Details of One Form of Clamp Meeting the Requirements of6.2FIG.6SpecimenGeometry8.Conditioning8.1Conditioning—Condition the test specimens at 2362°C and5065%relative humidity for not less than40 h prior to the test in accordance with Procedure A of Practice D618for those tests where conditioning is required.In cases of disagreement,the tolerances shall be61°C and62% relative humidity.8.2Where long-time effects such as crystallization,incom-patibility,and so forth,of materials are to be studied,condition the test specimens in accordance with Practice D832.9.Procedure9.1In establishing the brittleness temperature of a material, it is recommended that the test be started at a temperature at which50%failure is expected.Test a minimum of ten specimens at this temperature.If all of the specimens fail, increase the temperature of the bath by10°C and repeat the test using new specimens.If none of the specimens fail,decrease the bath temperature by10°C and repeat the test using new specimens.If the approximate brittleness temperature is not known,select the start temperature arbitrarily.9.2Prior to beginning a test,prepare the bath and bring the apparatus to the desired starting temperature.If the bath is cooled using dry ice,place a suitable amount of powdered dry ice in the insulated tank and slowly add the heat-transfer medium until the tank isfilled to a level30to50mm from the top.If the apparatus is equipped with a liquid nitrogen or CO2 cooling system and automatic temperature control,follow instructions provided by the manufacturer of the instrument for preparing and operating the bath.9.3Mount the test specimensfirmly in the clamping device. Secure the specimens with a torque wrench.To avoid excessive deformation of the specimens,use a torque suitable for the material being tested.N OTE6—It is recommended that a clamping torque of0.5660.01 N·m(560.1lb·in.)be used to mount the samples.If slippage of the specimens in the clamp occurs,increase the torque the minimum amount necessary to eliminate the slippage.9.4Mount the clamping device in the testing apparatus and lower the clamping device into the heat-transfer medium.If dry ice is being used as a coolant,maintain constant temperature by the judicious addition of small quantities of dry ice.If the apparatus is equipped with a liquid nitrogen or CO2cooling system and automatic temperature control,follow the manu-facturer’s instructions for setting and maintaining temperature.9.5After waiting for360.5min,record the temperature and deliver a single impact to the specimens.9.6Remove the clamping device from the testing apparatus and remove the individual specimens from the clamping device.Allow the specimens to warm up prior to being bent for inspection of cracks by leaving the specimens at room tem-perature for1min or by placing them in lukewarm water for10 to15s.Examine each specimen to determine whether or not it has failed.Failure is defined as the division of a specimen into two or more completely separated pieces or as any crack in the specimen which is visible to the unaided eye.Where a specimen has not completely separated,it shall be bent to an angle of90°in the same direction as the bend caused by the impact and examined for cracks at the bend.Record the number of failures and the temperature at which they were tested.9.7Increase or decrease the temperature of the bath in uniform increments of2or5°C and repeat the procedure until the lowest temperature at which none of the specimens fail and the highest temperature at which all of the specimens fail is determined.A minimum of four tests shall be conducted in that temperature range.New specimens are to be used for each test.10.Routine Inspection and Acceptance10.1Procedure A—For routine inspection of materials received from an approved supplier,it shall be satisfactory to accept lots on the basis of testing a minimum of ten specimens at a specified temperature as stated in the relevant material specifications.Not more thanfive shall fail(see Section9).10.2Procedure B—It shall be satisfactory to accept elas-tomeric composition on a basis of testingfive specimens at a specified temperature,as stated in the relevant material speci-fications.None shall fail.11.Calculation11.1Standard Method—Using the number of specimens that failed,calculate the percentage of failures at each tem-perature.Calculate the brittleness temperature of the material as follows:T b5T h1D T[~S/100!2~1/2!#where:T b=brittleness temperature,°C,T h=highest temperature at which failure of all the speci-mens occurs(proper algebraic sign must be used),°C,D T=temperature increment,°C,andS=sum of the percentage of breaks at each temperature (from a temperature corresponding to no breaksdown to and including T h).Derivations of the aboveformula are contained in other references.7,8N OTE7—Example:The following example illustrates application of this formula:Material—Plasticized poly(vinyl chloride)Number of Specimens Tested at Each Temperature—Ten. At−30°C,0failedAt−32°C,2failedAt−34°C,3failedAt−36°C,6failedAt−38°C,8failedAt−40°C,10failedAt−42°C,10failedThen:T h=−40°CD T=2S=0+20+30+60+80+100=290Since:T b=T h+D T[(S/100)−(1/2)]Then:T b=−40+4.8=−35.2°CBrittleness temperature,reported as−35°C.11.2Alternative Graphic Method —The value reported by this graphic method is essentially the same as that calculated by the standard method described in 11.1,but is obtained without determining either the highest temperature at which all speci-mens fail or the lowest at which all pass the test.When testing materials that possess a wide temperature range of brittleness transition,the graphic method also requires the testing of fewer sets of samples to determine the brittleness temperature.Select sets of ten specimens each in which both failures and nonfail-ures occur at four or more temperatures.Choose temperatures above and below the estimated 50%failure point.Plot the data on probability graph paper with temperature on the linear scale and percent failure on the probability scale.Select the tem-perature scale so that it represents a minimum of two divisions for each degree.Draw the best fitting straight line through these points.The temperature indicated at the intersection of the data line with the 50%probability line shall be reported as the brittleness temperature,T b .Where there is a question of conformance to the relevant material specification,the value obtained according to 11.1shall be accepted as the T b value.N OTE 8—The graphic method applied to the data from the example in Note 7is shown in Fig.7.The brittleness temperature,T b ,estimated to the nearest degree is −35°C.12.Report12.1Report the following information:12.1.1Reference to this test method,12.1.2Complete identification of the material tested,includ-ing type,source,manufacturer’s code designation,form in which supplied,and previous history,12.1.3Specimen type,dimensions,and method of prepara-tion,12.1.4Specimen conditioning methods,if any,including time elapsed since molding or annealing,12.1.5Torque used to secure the specimens,12.1.6Brittleness temperature to the nearest 1°C,12.1.7Type of test apparatus and heat-transfer medium used,12.1.8Method of calculation,and 12.1.9Date of test.12.2For routine inspection and acceptance testing only,the following shall be recorded instead of 12.1.6and 12.1.8:12.2.1Number of specimens tested,12.2.2Temperature of test,and 12.2.3Number of failures.13.Precision and Bias513.1Precision —Table 1is based on a round-robin test conducted in 1997involving three materials and nine labora-tories.Each laboratory made two determinations on each material.This study has been submitted to ASTM to be filed as a research report.13.1.1S r is the within-laboratory standard deviation of the average;r =2.8S r .(See 13.1.3for application of r .)13.1.2S R is the between-laboratory standard deviation of the average;R =2.8S R .(See 13.1.4for application of R .)13.1.3Repeatability —In comparing two test results for the same material,obtained by the same operator using the same equipment on the same day,those test results are to be judged not equivalent if they differ by more than the r value for the material and condition.13.1.4Reproducibility —In comparing two test results for the same material,obtained by different operators using differ-ent equipment on different days,those test results are to be judged not equivalent if they differ by more than the R value for the material and condition.(This applies between different laboratories or between different equipment within the same laboratory.)13.1.5Any judgement in accordance with 13.1.3and 13.1.4will have an approximate 95%(0.95)probability of being correct.13.2Bias —There are no recognized standards on which to base an estimate of bias for this test method.14.Keywords14.1brittle failure;brittleness temperature;elastomer;im-pact plastics5Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D20–1228.FIG.7Graphic Method for Determining the T b BrittlenessTemperature TABLE 1Precision and Bias DataMaterialsAverage S r S R r R #1Injection Molded PP −8.50.67 1.90 1.89 5.33#2Injection Molded PP −31.9 1.11 4.33 3.1112.12#3Die Cut PE−35.12.229.036.2225.28APPENDIXES(Nonmandatory Information)X1.STRIKER MECHANISM VELOCITY CALIBRATION FOR THE SOLENOID-ACTUATED BRITTLENESS TESTERX1.1Calibration is accomplished by measuring the height,h ,to which a steel ball,suspended on the striker mechanism of the tester,rises after the striker has had its upward motion halted by contact with a mechanical stop.The ball is acceler-ated in such a manner that the law governing a freely falling body applies.The velocity,v ,of the striker is readily calculated from the following expression:v 5=2ghX1.2Securing Ball Support —Remove either one of the nuts that fasten the striking bar guide rods to the solenoid armature yoke.Place the small hole of the ball support (Fig.X1.1)over the guide rod and replace and secure the nut.X1.3Adjusting Stroke of Striker —Remove the metal guard from around the solenoid.Spread open the rubber bumper (Fig.X1.2)and insert it around the armature.Replace the solenoid guard.Insert a typical rubber or plastic specimen into the specimen holder of the tester.Raise the striking mechanism by hand until the end of the stroke is reached.It is essential that,with the striking mechanism raised to its maximum height,the striker bar of the tester be in contact with the specimen but that the bar not be in the plane of the specimen.If the striker bar is not in contact with the specimen,the rubber bumper must be removed and replaced by a thinner bumper.Conversely,if the striker bar moves into the plane of the specimen,the bumper must be replaced by a thicker one.X1.4Placement of Ball and Measuring Tube —Place a 19-mm diameter steel ball on the ball holder.(In theory,theupward flight of the ball is independent of the mass of the ball.However,if the mass is too large,the motion of the striker bar will be impeded.)Clamp a glass or clear plastic tube with a minimum inside diameter of 25.4mm in a vertical position directly over the ball.The tube contains a scale divided into 5-mm intervals.Align the zero position on the scale with the top of the ball when the ball is at the top of the stroke of the striker mechanism.X1.5Measurement and Calculation —With the tester equipped as described above and devoid of test specimens and immersion medium,fire the solenoid and read the ball height to the closest 5mm.Make at least five measurements.Average all results and convert the average to metres.Determine the striker velocity,v ,from the following equation:v 5=2ghwhere:v =velocity,m/s,g =9.8m/s 2,andh =average ball height,m.N OTE X1.1—Calibration measurements are to be made with the tester supported on a nonresilient surface,such as a laboratory bench or concrete floor.Resilient mountings tend to absorb some of the striker energy causing low ball heightvalues.FIG.X1.1BallSupportFIG.X1.2RubberBumperX2.STRIKER MECHANISM VELOCITY CALIBRATION FOR THE SOLENOID-ACTUATED BRITTLENESS TESTERDURING ACTUAL TESTINGX2.1With the tester equipped with ball support,ball,and measuring tube(see Appendix X1),but without the rubber bumper(tester in normal operating condition)and devoid of test specimens and immersion medium,fire the solenoid and read the ball height to the closest5mm.Make ten measure-ments.From the lowest and highest ball height readings, determine the range in striker velocity,using the equation in X1.5.This range is termed“range of velocity at the top of the stroke.”X2.2With the tester equipped as described in X2.1,but also with test specimen(s)and immersion medium,conduct the brittleness test as outlined in Section9.Read the ball height each time the solenoid isfired.Convert the ball height to velocity as shown in X1.5.If the velocity lies within the predetermined range of velocity at the top of the stroke,the test shall be considered valid.If the speed lies outside of the predetermined range,the test shall be invalid and shall not be reported.If successive tests are found to be invalid,adjust-ments shall be made to bring the velocity at the top of the stroke within the acceptable,predetermined range.This is accomplished by reducing the number of specimens tested per impact or by changing from Type A to Type B specimens.X2.3The following example typifies the entire velocity calibration procedure for solenoid-actuated testers:X2.3.1Using the procedure of Appendix X1,the striker velocity at point of impact of a tester devoid of test specimens and immersion medium was found to be1.9m/s.This velocity is within the specified limits of5.1.1.X2.3.2Using the procedure of X2.1,with the tester devoid of test specimens and immersion medium,the range of striker velocity at the top of the stroke was found to be2.5to2.7m/s. This range becomes the acceptable range for this series of tests. The acceptable ranges shall be established each time the striker velocity at point of impact is determined(see Appendix X1). X2.3.3Using the procedure of X2.2,with the tester con-taining a test specimen(s)and immersion medium,the velocity at the top of the stroke during thefirst solenoidfiring was found to be2.5m/s.This velocity was within the acceptable range and the test was valid.X2.3.4The velocity at the top of the stroke during the second and third solenoidfirings were found to be2.4and2.3 m/s,respectively.These velocities are outside of the acceptable range and both tests are invalid.X2.3.5Adjustments were made to increase the velocity at the top of the stroke,using the procedures given in X2.2.X2.3.6The speeds at the top of the stroke during the fourth and all subsequent solenoidfirings were found to lie between 2.5and2.7m/s.The results of all these tests were valid.SUMMARY OF CHANGESCommittee D20has identified the location of selected changes to this standard since the last issue(D746-04) that may impact the use of this standard.(March1,2007)(1)Added1.3.(2)Revised standard references in2.1and deleted date refer-ences for the ISO standard in2.2.(3)Moved Note5into the Apparatus section.(4)Revised6.4and deleted old Note5.(5)Revised example calculation in11.1.。

Low Temperature Field-Effect in Crystalline Organic MaterialV. Y. Butko*†, J. C. Lashley* and A. P. Ramirez‡,¶*Los Alamos National Laboratory, Los Alamos, New Mexico, USA‡Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, NY, USA¶Columbia University, New York, NYMolecular organic materials offer the promise of novel electronic devices but also present challenges for understanding charge transport in narrow band systems. Low temperature studies elucidate fundamental transport processes. We report the lowest temperature field effect transport results on a crystalline oligomeric organic material, rubrene. We find field effect switching with on-off ratio up to 107 at temperatures down to 10 K. Gated transport shows a factor of ~10 suppression of the thermal activation energy in 10-50 K range and nearly temperature independent resistivity below 10 K.Interest in organic devices stems from their mechanical flexibility, their potential for interfacing to biological systems, and their ease of processing over large areas. [1-4]. Work on single-molecule devices also motivates the need for scalable approaches to integrated molecular electronics [5, 6] Unlike the development of inorganic semiconductor devices, applications for organics are well ahead of fundamental understanding, especially concerning scattering and trapping mechanisms and their chemical and morphological origins.One of the key questions for organic semiconductors is what fraction of charge injected by gate bias in a field effect transistor (FET) configuration is either itinerant or localized, the latter due to deep-level trapping. The most stringent test of localization is to cool such a device to very low temperatures where the mobility edge can be probed without the complication of thermal activation. Low-temperature time-of-flight experiments on high-quality single crystals of naphthalene and anthracene suggest that band transport with mobility values, µ > 100, is attainable [7]. In this work we present the first low-temperature measurements on field effect devices made from a crystalline oligomeric organic material, rubrene.The first organic single crystal FETs made from rubrene, pentacene, and tetracene had carrier mobility (µ) ≤1 cm2/(Vs) [8-11]. All of these devices demonstrated thermally activated resistivity, ρ =ρ0exp(E a/k B T), whereE a is an activation energy, below 270 K. Recent work [12,13] on rubrene single crystal FETs shows µ significantly higher than 1 cm2/Vs in the temperature range 300K - 100K but, below 180 K, charge transport is still semiconducting-like with E a ~ 70 meV. Rubrene (C42H28) is a molecule comprised of tetracene with four additional phenyl rings attached at the center positions. For crystal synthesis, we used a special batch of high-purity rubrene powder obtained from Aldrich. Crystal growth was achieved by successive runs using the horizontal physical vapor transport method of Laudise et. al. [14] using ultra high purity argon, at a flow rate of 0.5 ml/min. The source temperature was ramped slowly over a time period varying between 6 hours to two days, to the melting point 317 C. At the end of each run, the single crystals were visually examined for low mosaic spread by microscopy in cross-polarizers and the best crystals were recycled three times to further improve purity and crystallinity.FETs were fabricated in a manner similar to our previous work using colloidal graphite source-drain contacts, parylene gate barriers, and silver-paste gate electrodes [9, 11]. Measurements were also performed as in our previous work [9, 11]. The leakage current between the gate electrode and ground was ~10-14-10-13A over most of the gate-source voltage (V gs) range, and never exceeded 3×10-12A. Heat sinking of the leads in the cryostat was achieved by either mechanical clamping to a cooled sapphire block in a vacuum of 10-5 Torr or with 10 Torr pressure 4He exchange gas. Additional thermal sinking is achieved by the three Au leads (2 cm by 50 µm). Thermal cooling between the sample and gate is limited by the parylene layer (100µm × 100µm) and is greater than 10-4 W/K, assuming a parylene thermal conductivity similar to other polymers (≥ 0.01 W/(Km) [15]). At the highest power generated in our sample, we estimate temperature measurement error should not exceed ~2 K at the lowest temperatures. We emphasize that the above considerations address the rubrene lattice temperature and can only be used to bound an estimate of possible hot electron effects, to be discussed below.Fig.1 demonstrates hole-injecting FET current-voltage (I-V) characteristics for a representative device (#6) at both 300K and at 10K. We find at 300K, linearbehavior at small drain-source voltage (V ds) followed by saturation at higher V ds, behavior similar to that seen by other workers [12, 13]. (Sample geometries and room temperature mobilities for our devices are listed in Table 1.) We also find FET-like behavior at 10K in most samples. This behavior is qualitatively different in detail from that at 300K. In particular, the low-V ds behavior demonstrates a voltage threshold and does not fit the usual transport models, e.g. I d varying as V (ohmic), V2 (space charge limited current), or exp(V1/2) (Frenkel-Poole emission). We suspect that the strong super-linear dependence of I d on V ds (< V gs) is due to a combination of 1) contact barrier energy distribution, and 2) V ds-stimulated shallow trap emission. It is also important to account for the role of contact potentials [3, 16] in the high-voltage charge transport. Previous work on rubrene FETs demonstrates that four- and two-terminal measurements yield similar results [8]. In the present experiments, both at 300K and 10K (fig. 1), the dependence of I d on V gs is much stronger than on V ds in the high-voltage limit. This behavior, and the effective saturation of I d on V ds at V ds≥V gs implies that contact potentials do not dominate high voltage transport.Activation energy measurements performed at different values of V gs, as shown in fig. 2, probe the density of deep traps as the Fermi level approaches the valence band [9, 11]. For instance, a gate voltage of –50V decreases E a from ~0.15 eV to 25 meV in the temperature range 270-120K. This latter value of E a is almost 3 times less than reported for rubrene in the temperature range 180-100 K [12] and almost 6 times less than in our pentacene FETs [9]. A smaller E a implies a significantly lower density of deep charge traps in these crystals, and subsequent higher channel conductivity at low temperatures, compared to previous published studies. We associate this higher conductivity with higher purity of our starting materials for crystal growth.In Fig.3, we show I d versus temperature for three different rubrene FETs with data extending to lower temperatures than shown in fig. 2. Different values for E a can result from differences in processing and associated differences in trap densities within the first monolayer of rubrene at the interface to the gate barrier. A common feature to all devices, however, is a marked change in activation energy from E a ~ 25-53 meV, to E a ~ 2-5 meV at temperatures below 50K. Such behavior is often seen in small band gap systems, such as SmB6 and FeSi, and arises from shallow states which become observable after the majority conduction band becomes thermally depopulated [17, 18]. In our devices, parametric gate bias control allows us to probe such states by varying charge density while keeping temperature fixed, as we discuss next.Fig. 4 shows the low temperature dependence of the channel resistivity of rubrene FET device #2 calculated from the measured I d under the assumption of 1 nm channel depth [19] at different values of V gs for V ds = -125V. (Similar data were obtained for two other samples). These data clearly demonstrate gate-electric-field-induced crossover from thermally activated to nearly temperature independent transport as the hole Fermi energy moves toward the valence band [9, 11]. As discussed above, the temperature dependence of the channel resistance at the low-V gs observed in fig. 4 (inset) is due to a modificationof the density of trap states available for thermal excitation. Then, for increasing V gs above ~ -80V, E a falls below the thermal energy, and activated behavior is lost. Indeed, for the high voltages, the resistivity between 2K and 30K cannot be fit with a single E a value.The differential number of injected holes per unit area is given by dN = dV gs C/e, where C is the capacitance per unit areaof the gate-insulator and e is the elementary charge. Therefore the effective hole mobility (µeff) is a function ofV gs and can be calculated from the measured I d(V gs) dependence (see inset of the fig.1): µeff = (dI d/dV gs)Ld par/(ZV dsεε0). Here L is drain-source contact separation, d par is parylene thickness, Z is the contact width, ε = 2.65 is the parylene dielectric constant, and ε0 is the permittivity in vacuum. The mobility calculated for device #6 (fig.4, inset) displays three different regimes of the dependence of µeff on V gs: 1) subthreshold behavior below 35V; 2) exponential increase of thermally activated carriers for 35V < V gs < 65V and; 3) , above 65V, with m ~ 6.5. (Two other samples exhibited this behavior). We discuss this third region below.mgseffV∝µWe consider, below, two distinct transport scenarios that might explain the behavior at low temperature and high voltage. In the first scenario, we assume that all holes injected at the highest values of V gs are in the valence band and free. Under this assumption, one can consider the weak temperature dependence in fig.4 as an approach to degeneracy. The density of free holesin the active channel is thus the differential amount injected by the gate electrode between -86 and -126V. We find the areal density of free holes of ~ 5 × 1011 cm-2. Assuming a channel depth of 1 nm [19], the volume density of free holes is thus 5 × 1018 cm-3 (the rubrene molecular density is 1.5 × 1021 cm-3). The behavior of two-dimensional (2D) fermion gases in high-µ Si MOSFETs is known to be metallic-like (dρ/dT > 0) at these areal densities. However, such behavior is only observed for µ> 4 × 104 cm2/Vs [20], whereas for µeff ~ 0.5 (the highest value obtained here - fig. 4 (inset)), metallic behavior has never been observed. Both insulator-metal (Ioffe-Regel)[21, 22] and insulator-superconductor[23] transition 2D criteria also classify our system as non-†On leave from Ioffe Physical Technical Institute, Russian Academy of Science, Russiametallic. Even if our present system were three-dimensional, the observed value of µeff is too small for metallicity. In bulk P-doped silicon, for example, the limiting low temperature mobility is about 100 cm 2/Vs at the density where the system crosses over from a semiconductor to a degenerate gas [24]. Therefore, it is difficult to reconcile an assumption of free holes with the observed low µeff .References[1] P. Peumans, S. Uchida and S. R. Forrest, Nature 425, 158 (2003). [2] A. R. Volkel, R. A. Street and D. Knipp, Physical Review B 66, 195336 (2002). The second scenario incorporates the breakdown of the thermal activation model and a low µeff at low temperatures and invokes V ds -induced trap emission followed by hopping, quantum tunneling, or hot electron transport. In general, trapped holes can hop or tunnel in real space between traps. The high-V ds fields of ~104 V/cm are most likely large enough to generate emission from trap states that are active at the low temperatures, and both hopping and tunneling can be activated by the shift of the Fermi level to the valence band. Both tunneling and hopping in the gap require a small average distance between traps and therefore a high density of trap states, as is typically observed in molecular compounds in proximity to the valence band [2]. An estimate of this distance obtained from the density of trapped injected carriers in our systems is ~10 nm, making such a mechanism unlikely at present carrier densities. On the other hand, trapped holes can be accelerated into the valence band, providing hot carrier transport between trapping events. Assuming again a 10 nm trap separation, one finds final kinetic energies of order 100K before trapping events. The central question that remains concerns the nature of trap states from which emission occurs. These states pin the Fermi level at low temperatures and the presently accessible voltages. The rapid mobility increase with V gs suggests that such pinning is due to a sharp rise in the density of states near a mobility edge [25].[3] I. H. Campbell and D. L. Smith, Solid State Physics 55, 1 (2001). [4] S. F. Nelson, Y. Y. Lin, D. J. Gundlach, et al., Applied physics letters 72, 1854 (1998). [5] C. Joachim, J. K. Gimzewski and A. Aviram, Nature 408, 541 (2000). [6] A. Nitzan and M. A. Ratner, Science 300, 1384 (2003). [7] W. Warta and N. Karl, Physical Review B 32, 1172 (1985). [8] V. Podzorov, V. M. Pudalov and M. E.Gershenson, Applied physics letters 82, 1739 (2003). [9] V. Y. Butko, X. Chi, D. V. Lang, et al., Appl. Phys. Lett. 83, 4773 (2003).[10] R. W. I. d. Boer, T. M. Klapwijk and A. F. Morpurgo, Appl. Phys. Lett. 83, 4345 (2003).[11] V. Y. Butko, X. Chi and A. P. Ramirez, Solid State Communications 128, 431 (2003).[12] V. Podzorov, E. Menard, A. Borissov, et al., cond-mat/0403575 (2004).[13] R. W. I. d. Boer, M. E. Gershenson, A. F. Morpurgo, et al., cond-mat/0404100 (2004).[14] R. A. Laudise, C. Kloc, P. G. Simpkins, et al., Journal of crystal growth 187, 449 (1998).[15] D. T. Morelli, J. Heremans, M. Sakamoto, et al., Phys. Rev. Lett. 57, 869 (1986).In conclusion, we have shown that lowtemperature charge transport in a rubrene FET exhibits temperature dependence that crosses over from activated at high temperature to almost temperature-independent at 10K. The electric field dependence at the lowest temperatures suggests that trapping dominates charge transport within a hot-electron framework. Further work is needed in improving crystal purity to reduce trap density, and in improving the gate dielectric to increase injected charge density.[16] A. Kahn, N. Koch and W. Y. Gao, Journal of Polymer Science, Part B (Polymer Physics) 41, 2529 (2003).[17] J. C. Cooley, M. C. Aronson, Z. Fisk, et al., Physical Review Letters 74, 1629 (1995).[18] S. Paschen, E. Felder, M. A. Chernikov, et al., Phys. Rev. B 56, 12916 (1997).[19] G. Horowitz, Advanced Functional Materials 13, 53 (2003).[20] E. Abrahams, S. V. Kravchenko and M. P. Sarachik, Reviews of modern physics 73, 251 (2001). We are especially grateful to D. Lang for severaluseful discussions. We also acknowledge helpful discussions with C. M. Varma, R. de Picciotto, C. Kloc, X. Chi, X. Gao, S. Trugman and G. Lawes. We acknowledge support from the Laboratory Directed Research and Development Program at Los Alamos National Laboratory and by the DOE Office of Basic Energy Science. [21] A. F. Ioffe and A. R. Regel, Prog. Semicond. 4, 237 (1960).[22] M. R. Graham, C. J. Adkins, H. Behar, et al., Journal of Physics: Condensed Matter 10, 809 (1998). [23] D. B. Haviland, Y. Liu and A. M. Goldman, Physical Review Letters 62, 2180 (1989).[24]G. L. Pearson and J. Bardeen, Phys. Rev. B 75, 865 (1949). [25] D. V. Lang, X. Chi, T. Siegrist, et al., cond-mat/0312722 (2003).Table 1.Sample L(µm) ±20% Z(µm)±20%d par(µm)±25%µ(cm2/Vs)±30%#1 170 200 0.8 5#2 100 110 1.25 6#4 150 160 0.5 12 (285 K) #6 100 150 1.25 5#12 100 100 1 2.5 #18 150 250 0.8 3 Figure 1. The main parts show room temperature characteristics of the same rubrene single crystal FET at 300 K and 10 K. In the inset to fig. 1(a) is plotted I d versus V gs for the sample #4 with V ds = -51 V, # 6 with V ds = -61 V and # 2 with V ds = -61 V. In the inset to fig.1(b) is plotted I d versus V gs for the sample #12 with V ds = -85 V, # 6 with V ds = -130 V and # 18 with V ds = -70 V. Figure 2. Drain current temperature dependence of rubrene single crystal FET at different gate-source voltages. Inset: Dependence of the thermal activation energy onV gs.Figure 3. Drain current temperature dependence in 3 different rubrene single crystal FETs.Figure 4. Resistivity temperature dependence of rubrene single crystal FET #2 at different gate-source voltages in temperaturerange 30K-2K. In the inset dependence of the mobility on V gs in the sample #6 at 10 K is shown.01x10-52x10-501x10-62x10-6- D r a i n c u r r e n t (A )-V (V)- V ds (V)- D r a i n c u r r e n t (A )0.0020.0040.0060.00810-1110-910-710-510-31/Temperature (1/K)- D r a i n c u r r e n t (A )Figure 2.0.000.020.040.060.080.1010-1010-810-61/Temperature (1/K)- D r a i n c u r r e n t (A )Figure 3.5101520253010-710-3101105109Temperature (K)R e s i s t i v i t y (Ωc m )Figure 1.Figure 4.。

低温、紫外胁迫对植物的影响的英语1. The effects of low temperature and UV stress on plants have been extensively studied.2. Researchers have investigated the impact of low temperature and UV stress on different plant species.3. This study aims to analyze the responses of plants to low temperature and UV stress.4. The effects of low temperature and UV stress can be detrimental to plant growth and development.5. Understanding the mechanisms underlying the response of plants to low temperature and UV stress is important for crop breeding.6. Low temperature and UV stress can induce significant changes in physiological and biochemical processes in plants.7. Recent studies have shown that low temperature and UV stress can alter the expression of genes involved in plant defense mechanisms.8. The effects of low temperature and UV stress on plants are mediated by various signaling pathways.9. Plant tolerance to low temperature and UV stress can be enhanced through genetic modification.10. The effects of low temperature and UV stress on plants can vary depending on the duration and intensity of exposure.11. Low temperature and UV stress can lead to the accumulation of reactive oxygen species in plants.12. The production of antioxidants is increased in response to low temperature and UV stress in plants.13. Certain plant species have developed specific mechanisms to cope with low temperature and UV stress.14. The effects of low temperature and UV stress on photosynthesis in plants have been extensively studied.15. Plant growth and development can be hindered by low temperature and UV stress.16. The effects of low temperature and UV stress on plant metabolism have been well-documented.17. Low temperature and UV stress can affect the nutritional composition of plants.18. Plants exposed to low temperature and UV stress may exhibit changes in leaf morphology.19. The effects of low temperature and UV stress on plant reproductive processes have been investigated.20. Stress-responsive genes are upregulated in plants subjected to low temperature and UV stress.21. Low temperature and UV stress can lead to alterations in plant hormone signaling pathways.22. Plant defense mechanisms are activated in response to low temperature and UV stress.23. The effects of low temperature and UV stress on plant water relations have been studied.24. Low temperature and UV stress can induce cell membrane damage in plants.25. The impact of low temperature and UV stress on plant yield and quality has been evaluated.26. Strategies for mitigating the effects of low temperature and UV stress on plants are being explored.。

科 技 前 沿DOI：10.16661/ki.1672-3791.2108-5042-9861屋面防水材料在高原环境下的适用性对比研究王越1 张寿红1 姜海涛1 王天亮2,3 韩英1(1.中国铁路青藏集团有限公司 青海西宁 810000；2.省部共建交通工程结构力学行为与系统安全国家重点实验室(石家庄铁道大学) 河北石家庄 050043；3.道路与铁道工程安全保障省部共建教育部重点实验室(石家庄铁道大学) 河北石家庄 050043)摘 要：目前，为了新型防水材料在高原地区的工程应用提供数据参考和选材建议，该文将冻融循环、太阳辐射等高原环境因素考虑进试验测定了4种不同防水材料的拉伸性能、不透水性能、低温柔性、低温弯折性、耐候性和粘滞性等物理力学性能。

通过综合对比4种防水材料各种指标发现，将喷涂和成型非固化橡胶沥青防水涂料组合后，在各种物理力学性能上优于单一的材料和SBS防水材料，可有效解决搭缝开裂、与基面接触等问题；可应用于异型结构处，对防水薄弱环节有较好的防护作用；可抵御不利条件自身的老化和性能削弱。

因此，可将该组合防水材料作为高原气候条件下的首选材料应用于青藏高原房建工程屋面防水工程中。

关键词：新型防水材料 冻融循环 太阳辐射 物理力学性能中图分类号：O 319.56 文献标识码：A 文章编号：1672-3791(2021)08(b)-0008-09 Comparative Study on the Applicability of Roofing WaterproofMaterials in Plateau EnvironmentWANG Yue1 ZHANG Shouhong1 JIANG Haitao1 WANG Tianliang2,3 HAN Ying1(1.China Railway Qinghai-Tibet Group Co., Ltd., Xining, Qinghai Province, 810000 China; 2.State KeyLaboratory of Mechanical Behavior and System Safety of Traff ic Engineering Structures JointlyBuilt by the Ministry of Transport, Shijiazhuang Tiedao University, Shijiazhuang, Hebei Province,050043 China; 3.Key Laboratory of Roads and Railway Engineering Safety Control of Ministryof Education, Shijiazhuang Tiedao University, Shijiazhuang, Hebei Province, 050043 China) Abstract:At present, in order to provide data reference and material selection suggestions for the engineering application of new waterproof materials in plateau areas, this paper takes the plateau environmental factors such as freeze-thaw cycle and solar radiation into account, and measures the physical and mechanical properties of four different waterproof materials, such as tensile properties, impermeability, low-temperature f lexibility, low-temperature bending, weather resistance and viscosity. Through a comprehensive comparison of the various indicators of the four waterproof materials, by comprehensively comparing the various indicators of the four waterproof materials, it is found that the combination of spraying and forming non-curing rubber asphalt waterproof coating is better than a single material and SBS waterproof material in various physical and mechanical properties. It can effectively solve the problems基金项目：中国国家铁路集团有限公司科技研发计划（项目编号：N2019G015）；中国青藏铁路集团有限公司科技 研发计划（项目编号：QZ2019-Q01）。

__________________________________________________________________________________________________________________________________________ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright © 2015 SAE InternationalAll rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970 (outside USA) Fax: 724-776-0790 Email: CustomerService@ SAE WEB ADDRESS: SAE values your input. To provide feedbackon this Technical Report, please visit /technical/standards/J300_201501 SURFACE VEHICLESTANDARD J300™ JAN2015Issued 1911-06 Revised 2015-01 Superseding J300™ APR2013 Engine Oil Viscosity ClassificationRATIONALEThis revision continues the process of extending the SAE Engine Oil Viscosity Classification system to lower high-temperature high-shear-rate (HTHS) viscosities by adding two new high-temperature viscosity grades – SAE 12 and SAE 8 – to SAE J300 with minimum HTHS viscosities of 2.0 and 1.7 mPa·s respectively. The benefit of establishing new viscosity grades is to provide a framework for formulating lower HTHS engine oils in support of the ongoing quest of Original Equipment Manufacturers (OEMs) to improve fuel economy.The 100°C kinematic viscosity (KV100) ranges of the new viscosity grades overlap to provide adequate formulating space for these grades. How to assign a single high-temperature viscosity grade to an engine oil with KV100 in the overlap regions is covered in Section 6 of this document.1. SCOPEThis SAE Standard defines the limits for a classification of engine lubricating oils in rheological terms only. Other oil characteristics are not considered or included.2. REFERENCES2.1 Applicable DocumentsThe following publications form a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply.2.1.1 SAE PublicationsAvailable from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), .SAE J1510Lubricants for Two-Stroke-Cycle Gasoline Engines SAE J1536 Two-Stroke-Cycle Engine Oil Fluidity/Miscibility Classification2010-01-2286 Covitch, M., Brown, M., May, C., Selby, T. et al., "Extending SAE J300 to Viscosity Grades below SAE 20," SAE Int. J. Fuels Lubr. 3(2):1030-1040, 2010, doi:10.4271/2010-01-2286.2.1.2 ASTM PublicationsAvailable from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, SAE INTERNATIONAL J300™ Revised JAN2015 Page 2 of 9 ASTM D97 Standard Test Method for Pour Point of Petroleum OilsASTM D445 Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and the Calculation of Dynamic Viscosity)ASTM D2500 Standard Test Method for Cloud Point of Petroleum OilsASTM D3244 Standard Practice for Utilization of Test Data to Determine Conformance with SpecificationsASTM D3829 Standard Test Method for Predicting the Borderline Pumping Temperature of Engine OilASTM D4683 Standard Test Method for Measuring Viscosity at High Temperature and High-Shear Rate by Tapered Bearing SimulatorASTM D4684 Standard Test Method for Determination of Yield Stress and Apparent Viscosity of Engine Oils at Low TemperatureASTM D4741 Standard Test Method for Measuring Viscosity at High Temperature and High-Shear Rate by Tapered-Plug ViscometerASTM D5133 Standard Test Method for Low Temperature, Low Shear Rate, Viscosity/Temperature Dependence of Lubricating Oils Using a Temperature-Scanning TechniqueASTM D5293 Standard Test Method for Apparent Viscosity of Engine Oils Between –30 and –5 °C Using the Cold-Cranking SimulatorASTM D5481 Standard Test Method for Measuring Apparent Viscosity at High-Temperature and High-Shear Rate by Multicell Capillary Viscometer2.1.3 Other PublicationsCEC L-36-90 The Measurement of Lubricant Dynamic Viscosity Under Conditions of High ShearCRC Report No. 409 Evaluation of Laboratory Viscometers for Predicting Cranking Characteristics of Engine Oils at0 °F and –20 °F, April 19682.2 Related PublicationsThe following publications are provided for information purposes only and are not a required part of this SAE Technical Report.2.2.1 ASTM PublicationsAvailable from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, ASTM Data Series DS 62 The Relationship Between High-Temperature Oil Rheology and Engine Operation -A Status ReportASTM STP 1068 High-Temperature, High-Shear Oil Viscosity - Measurement and Relationship toEngine OperationASTM STP 1143 Low-Temperature Lubricant Rheology: Measurement and Relevance to EngineOperationASTM Research Report RR-D02-1442Cold Starting and Pumpability Studies in Modern EnginesASTM Research Report D02-1767 Interlaboratory Study to Establish Precision Statements for ASTM D4683-10,D5481-10 and D4741-12SAE INTERNATIONAL J300™ Revised JAN2015 Page 3 of 9 3. SIGNIFICANCE AND USEThe limits specified in Table 1 are intended for use by engine manufacturers in determining the engine oil viscosity grades to be used in their engines, and by oil marketers in formulating, manufacturing, and labeling their products. Oil marketers are expected to distribute only products which are within the relevant specifications in Table 1.The application of ASTM D3244 is used only for dispute resolution and shall not modify the limiting values in Table 1.Two series of viscosity grades are defined in Table 1: (a) those containing the letter W and (b) those without the letter W. Single viscosity-grade oils (“single-grades”) with the letter W are defined by maximum low-temperature cranking and pumping viscosities, and a minimum kinematic viscosity at 100 °C. Single-grade oils without the letter W are based on a set of minimum and maximum kinematic viscosities at 100 °C, and a minimum high-shear-rate viscosity at 150 °C. The shear rate will depend on the test method used. Multiviscosity-grade oils (“multigrades”) are defined by both of the following criteria:a. Maximum low-temperature cranking and pumping viscosities corresponding to one of the W grades, andb. Maximum and minimum kinematic viscosities at 100 °C and a minimum high-shear-rate viscosity at 150 °C corresponding to one of the non-W grades.Table 1 - SAE viscosity grades for engine oils (1)(2)Caution: kinematic viscosity ranges for SAE 8 to SAE 20 viscosity grades partially overlap. How to assign a single viscosity grade to an engine oil satisfying the kinematic viscosity specifications of more than one grade is covered in Section 6 of this document.SAE Viscosity GradeLow-Temperature (°C) Cranking Viscosity (3), mPa·s Max Low-Temperature (°C) Pumping Viscosity (4) mPa·s Max with No Yield Stress (4) Low-Shear-Rate Kinematic Viscosity (5) (mm 2/s) at 100 °C Min Low-Shear-Rate Kinematic Viscosity (5) (mm 2/s) at 100 °C Max High-Shear-Rate Viscosity (6) (mPa·s) at 150 °C Min 0W 6200 at –35 60 000 at –40 3.8 — — 5W 6600 at –30 60 000 at –35 3.8 — — 10W 7000 at –25 60 000 at –30 4.1 — — 15W 7000 at –20 60 000 at –25 5.6 — — 20W 9500 at –15 60 000 at –20 5.6 — — 25W 8 12 13 000 at –10 — — 60 000 at –15 — — 9.3 4.0 5.0 — <6.1 <7.1 1.7 2.0 16 — — 6.1 <8.2 2.3 20 — — 6.9 <9.3 2.6 30 — — 9.3 <12.5 2.9 40 — — 12.5 <16.3 3.5 (0W-40, 5W-40, and 10W-40 grades) 40 — — 12.5 <16.3 3.7 (15W-40, 20W-40, 25W-40, 40 grades) 50 — — 16.3 <21.9 3.7 60 — — 21.9 <26.1 3.71. Notes—1 mPa·s = 1 cP; 1 mm /s = 1 cSt2. All values, with the exception of the low-temperature cranking viscosity, are critical specifications as defined by ASTM D3244 (see text, Section7.)3. ASTM D5293: Cranking viscosity – The non-critical specification protocol in ASTM D3244 shall be applied with a P value of 0.95.4. ASTM D4684: Note that the presence of any yield stress detectable by this method constitutes a failure regardless of viscosity.5. ASTM D4456. ASTM D4683, ASTM D4741, ASTM D5481, or CEC L-36-90. 4. LOW-TEMPERATURE TEST METHODSThe low-temperature cranking viscosity is measured according to the procedure described in ASTM D5293 and is reported in milliPascal·seconds (centipoise). Viscosities measured by this method have been found to correlate with the ability of engines to start at low temperature.SAE INTERNATIONAL J300™ Revised JAN2015 Page 4 of 9 The pumping viscosity is a measure of an oil's ability to flow to the engine oil pump and provide adequate oil pressure during the initial stages of operation. The pumping viscosity is measured in milliPascal·seconds (centipoise) according to the procedure in ASTM D4684. This procedure uses the Mini-Rotary Viscometer to measure either the existence of yield stress or the viscosity in the absence of measured yield stress after the sample has been cooled through a prescribed slow cool (so-called TP1) cycle. This cooling cycle has predicted as failures several SAE 10W-30 and SAE 10W-40 engine oils which are known to have suffered pumping failures in the field after short-term (two days or less) cooling. These field failures are believed to be the result of the oil forming a gel structure that results in excessive yield stress and/or viscosity of the engine oil. The significance of the ASTM D4684 method is projected from the preceding SAE 10W-30 and SAE 10W-40 data.Limited test work has shown that in a few specific instances, borderline pumping temperature (ASTM D3829), and/or Scanning Brookfield method (ASTM D5133) can provide additional information regarding low-temperature performance. It is suggested that these tests be conducted when formulating new engine oils, or when there are significant changes in base oil or additive components of existing products.Because engine pumping, cranking, and starting are all important at low temperatures, the selection of an oil for winter operation should consider both the viscosity required for successful oil flow, as well as that for cranking and starting, at the lowest ambient temperature expected.A manufacturer may not release a product if its low-temperature cranking viscosity as measured by the manufacturer exceeds the maximum limit for its W grade. Similarly, a manufacturer may not release a product if its CCS viscosity as measured by the manufacturer is less than or equal to the stated limit of the next lower W grade. If multiple, operationally-valid CCS measurements are obtained at a given temperature, the average value is to be used to judge suitability for release. Appendix A contains examples of the application of ASTM D3244 in resolving disputes between laboratories as to whether a product conforms to a non-critical cranking viscosity specification.5. HIGH-TEMPERATURE TEST METHODSKinematic viscosity at 100 °C is measured according to ASTM D445, and the results are reported in mm2/s (centistokes). Kinematic viscosities have been related to certain forms of oil consumption and have been traditionally used as a guide in selecting oil viscosity for use under normal engine operating temperatures. Also, kinematic viscosities are widely used in specifying oils for applications other than in automotive engines.High-temperature high-shear-rate (HTHS) viscosity measured at 150 °C and reported in mPa·s (centipoise) is widely accepted as a rheological parameter which is relevant to high-temperature engine performance. In particular, it is generally believed to be indicative of the effective oil viscosity in high-shear components of an internal combustion engine (for example, within the journal bearings and between the rings and cylinder walls) under severe operating conditions. While the specific temperature and shear rate conditions experienced by an oil in a particular application depend on mechanical design and operating parameters, the measurement conditions specified in Table 1 are representative of a wide range of engine operating conditions.Many commercial engine oils contain polymeric additives for a variety of purposes, one of the most important of which is viscosity modification. Specifically, the use of such additives in creating multigrade oils is commonplace. However, oils containing a significant polymeric additive concentration, whether for viscosity modification or another lubricant function, are generally characterized by having a non-Newtonian, “shear thinning” viscosity (i.e., a viscosity which decreases with increasing shear rate).To insure that polymer-containing oils do not create a situation in which the viscosity of the oil decreases to less than a specified limit, minimum values of HTHS viscosity are assigned to each of the non-W viscosity grades in Table 1. A special situation exists regarding the SAE 40 grade. Historically, SAE 0W-40, 5W-40, and 10W-40 oils have been used primarily in light-duty engines. These multigrade SAE 40 oils must meet a minimum HTHS viscosity limit of 3.5 mPa·s.In contrast, SAE 15W-40, 20W-40, 25W-40, and 40 oils have typically been used in heavy-duty engines. The manufacturers of such engines have required HTHS viscosity limits consistent with good engine durability in high-load, severe service applications. Thus, SAE 15W-40, 20W-40, 25W-40, and single-grade 40 oils must meet a minimum HTHS viscosity limit of 3.7 mPa·s.There are three acceptable methods for the measurement of HTHS viscosity. For rotational viscometer methods ASTM D4683 and CEC L-36-90 (ASTM D4741), the shear rate is 1.0 x 106 s–1. For the capillary viscometer method, ASTMSAE INTERNATIONAL J300™ Revised JAN2015 Page 5 of 9 D5481, the shear rate is 1.4 x 106 s–1 at the wall. The latter shear rate has been found to provide HTHS viscosities in the capillary viscometer that are equivalent to those obtained by the rotational viscometer methods.6. LABELINGIn properly describing the viscosity grade of an engine oil according to this document, the letters “SAE” must precede the grade number designation. In addition, for multigrade oil formulations this document requires that the W grade precede the non-W grade, and that the two grades be separated by a hyphen (i.e., SAE 10W-30). Other forms of punctuation or separation are not acceptable.Engine oils not meeting the technical requirements of any viscosity grade in this document shall not bear any SAE viscosity grade on the label.It is possible for an engine oil to meet the kinematic viscosity requirements of more than one high temperature viscosity grade (SAE 8 through SAE 20). In labeling a single-grade or multigrade oil meeting the kinematic viscosity requirements of more than one grade, only the highest viscosity grade satisfied by the HTHS viscosity shall be referred to on the label. Examples for proper labeling are provided in Table 2.Table 2 – Labeling examplesKinematic Viscosity High-Shear-Rate-Viscosity(mm2/s) at 100°C (mPa·s) at 150°C SAE Viscosity Grade7.0 2.6 207.0 2.4 167.0 2.1 125.6 2.1 125.6 1.9 8Most oils will meet the viscosity requirements of at least one of the W grades. Nevertheless, consistent with historic practice, any Newtonian oil may be labeled as a single-grade oil (either with or without a W). Oils which are formulated with polymeric viscosity index improvers for the purpose of making them multiviscosity-grade products are non-Newtonian and must be labeled with the appropriate multiviscosity grade (both W and high-temperature grade). Since each W grade is defined on the basis of maximum cranking and pumping viscosities as well as minimum kinematic viscosities at 100 °C, it is possible for an oil to satisfy the requirements of more than one W grade. In labeling either a W grade or a multiviscosity grade oil, only the lowest W grade satisfied may be referred to on the label. Thus, an oil meeting the requirements for SAE grades 10W, 15W, 20W, 25W, and 30 must be referred to as an SAE 10W-30 grade only.An oil must meet the pumping requirements of the lowest W grade satisfied by the cranking viscosity. If the W grade defined by the pumping viscosity is higher than the lowest grade satisfied by the cranking viscosity, the oil does not meet the requirements of this document.The low temperature limits in Table 1 are those derived by the ASTM Low Temperature Engine Performance task force from engine studies conducted in the 1990’s [ASTM STP 1143]. Individual equipment manufacturers may use these limits as guidelines to recommend the appropriate winter grade of engine oil, or may apply more limiting criteria (cranking viscosity, pumping viscosity or other) to oils that they recommend for use in their engines.If the kinematic viscosity at 100 °C does not meet the requirements of the lowest W grade satisfied by the cranking viscosity, then the oil does not meet the requirements of this document.Some engine oils are prediluted, usually to assist in mixing with fuel when used in certain two-stroke-cycle engines. If any viscosity grade in SAE J300 is used to describe a prediluted engine oil, the grade indicated should relate to the viscosity of the oil in its undiluted state. In displaying SAE J300 viscosity grades of prediluted oils, containers should indicate that the SAE grade applies to the oil in its undiluted state.More accurately, the rheological properties of two-stroke-cycle engine oils should be identified using the terminology and grades described in SAE J1536. Further information on prediluted oils is also provided in SAE J1510.7. NOTES7.1 Marginal IndiciaA change bar (I) located in the left margin is for the convenience of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications, nor in documents that contain editorial changes only.PREPARED BY THE SAE FUELS AND LUBRICANTS TC 1 - ENGINE LUBRICATIONAPPENDIX AThe following examples show the use of ASTM D3244 in resolving disputes between laboratories as to whether a product conforms to a non-critical cranking viscosity specification. Each example starts with a summary statement, with the details of the case shown in the numbered sections.CAUTION: For the purpose of illustration, the reproducibility used in the examples below is that shown in ASTM D5293 for the automated CCS device with a methanol bath (7.3%). The user of this version of SAE J300 is cautionedto refer to the most current version of ASTM D5293 to determine the appropriate reproducibility of the specificlow-temperature cranking viscosity method to use in any dispute.Example 1 -- When CCS result indicates a higher grade, with Assigned Test Value inside Acceptance LimitA user measures CCS of an SAE 5W-X oil and claims it to be an SAE 10W-X grade. The Assigned Test Value is within the Acceptance Limit. Resolution: There is insufficient evidence to conclude that the oil should have been labeled as an SAE 10W-X.1. A manufacturer measures the CCS viscosity per ASTM D5293-04 of oil A as 6550 mPa·s @ –30 °C.2. The manufacturer releases the product, oil A, as an SAE 5W-X oil, since the test result is less than 6600 mPa·smaximum.3. A user measures the CCS viscosity of oil A (that is branded as SAE 5W-X) at –30 °C and obtains a result of6750 mPa·s. CCS Reproducibility is 7.3% in this example.4. Then per ASTM D3244-07 paragraph 7.3.5 (Eq. 2):a. The Acceptance Limit, AL, (based on an average of 2 results) is equal to: 6600 mPa·s + {0.255 x (6600 x 0.073)x 1.645} = 6802, where 0.255 and 1.645 are values from ASTM D3244-07 Figure 1.b. The absolute difference between the manufacturer's result and the user's result = |6550 - 6750| = 200.c. Reproducibility of the test method in this example at 6600 mPa·s is: 6600 x 0.073 = 482.d. Since the difference of 200 is less than 482, both results can be used to calculate the Assigned Test Value, ATV.ATV = (6550 + 6750)/2 = 6650.e. Since the ATV (6650) is less than the AL (6802), there is insufficient evidence to conclude that oil A should havebeen labeled as an SAE 10W-X.Example 2 - CCS result exceeds grade maximum limitA manufacturer measures the CCS above the maximum limit for the targeted grade. Resolution: CCS can be measured again one or more times and the average taken. If the average remains above the maximum limit, the oil can not be released in the target grade.1. A manufacturer measures the CCS viscosity per ASTM D5293-04 of oil B as 6650 mPa·s @ –30 °C.2. The product, oil B, cannot be released as an SAE 5W-X oil without further investigation or rework, since it exceeds the6600 limit. The manufacturer has the option of re-measuring CCS viscosity @ –30 °C as many times as it chooses to determine if the average value is less than the 6600 limit.Example 3 - When CCS result indicates a higher grade, with Assigned Test Value outside Acceptance LimitA user measures the CCS of an SAE 5W-X oil and finds it to be an SAE 10W-X grade. The Assigned Test Value is outside the Acceptance Limit for SAE 5W-X. Resolution: The parties need to conduct further analysis to determine whether the oil meets SAE 5W-X limits.1. A manufacturer measures the CCS viscosity per ASTM D5293-04 of oil C as 6590 mPa·s @ –30 °C.2. The manufacturer releases the product, Oil C, as an SAE 5W-X oil.3. A user measures the CCS viscosity of Oil C (that is branded as SAE 5W-X) at –30 °C and obtains a result of7050 mPa·s; ASTM D5293 reproducibility is 7.3% in this example.4. Then per ASTM D3244-07 paragraph 7.3.5 (Eq. 2):a. The Acceptance Limit is the same as example 1, 6802 mPa·s.b. The absolute difference between the manufacturer's result and the user's result = | 6590 - 7050 | = 460.c. Reproducibility of the test method in this example at 6600 mPa·s is: 6600 x 0.073 = 482.d. Since the difference of 460 is less than 482, both results can be used to calculate the Assigned Test Value, ATV.ATV = (6590 + 7050)/2 = 6820.e. Since the ATV (6820) exceeds the AL (6802), further investigation by the parties involved is necessary to resolvethe discrepancy.Example 4 - When CCS result indicates a higher grade but cannot calculate Assigned Test ValueA user measures the CCS of an SAE 5W-X oil and claims it to be an SAE 10W-X grade. The Assigned Test Value (ATV) can not be calculated. Resolution: The parties need to determine why the CCS results exceed the test reproducibility.1. A manufacturer measures the CCS viscosity per ASTM D5293-04 of oil C as 6450 mPa·s @ –30 °C.2. The manufacturer releases the product oil C as an SAE 5W-X oil.3. A user measures the CCS viscosity of oil C (that is branded as SAE 5W-X) at –30 °C and obtains a result of7150 mPa·s; ASTM D5293 reproducibility is 7.3% in this example.4. Then per D3244-07 paragraph 7.3.5 (Eq. 2):a. The Acceptance Limit is the same as example 1, 6802 mPa·s.b. The absolute difference between the manufacturer's result and the user's result = | 6450 - 7150 | = 660.c. Reproducibility of the test method in this example at 6600 mPa·s is: 6600 x 0.073 = 482.d. Since the difference of 660 is larger than 482, the results can not be used to calculate the Assigned Test Value,ATV.e. Further investigation by the parties involved is necessary to resolve why the measured values exceed theReproducibility stated in ASTM D5293-04.Example 5 - When CCS result indicates a lower grade than labeled, with Assigned Test Value inside Acceptance LimitA user measures the CCS of an SAE 5W-X oil and claims it to be an SAE 0W-X. The Assigned Test Value is within the Acceptance Limit for SAE 5W-X. Resolution: There is insufficient evidence to conclude that the oil should have been labeled as an SAE 0W-X.1. A manufacturer measures the CCS viscosity per ASTM D5293-04 of oil D as 6250 mPa·s @ –35 °C.2. The manufacturer releases the product, oil D, as an SAE 5W-X oil.3. A user measures the CCS viscosity of oil D (that is branded as an SAE 5W-X) at –35 °C and obtains a result of6000 mPa·s. CCS reproducibility is 7.3% in this example.4. Then per ASTM D3244-07 paragraph 7.3.5 (Eq. 2):a. The Acceptance Limit, AL, for a 0W (–35 °C test temperature) is equal to: 6200 mPa·s + {0.255 x (6200 x 0.073)x (-1.645)} = 6010, where 0.255 and -1.645 are values from ASTM D3244-07 Figure 1.b. The absolute difference between the manufacturer's result and the user's result = | 6250 - 6000 | = 250.c. Reproducibility of the test method in this example at is: 6200 x 0.073 = 453.d. Since the difference of 250 is less than 453, both results can be used to calculate the Assigned Test Value, ATV.ATV = (6250 + 6000)/2 = 6125.e. Since the ATV (6125) exceeds the AL (6010), there is insufficient evidence to conclude that this product, oil D,should have been labeled as SAE 0W-X rather than SAE 5W-X.。

第４２卷第２期２０２４年３月贵州师范大学学报（自然科学版）ＪｏｕｒｎａｌｏｆＧｕｉｚｈｏｕＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ（ＮａｔｕｒａｌＳｃｉｅｎｃｅｓ）Ｖｏｌ．４２．Ｎｏ．２Ｍａｒ．２０２４引用格式：吕勇，许学微，陈庆富，等．苦荞种子活力测定方法与其田间成苗率的相关性［Ｊ］．贵州师范大学学报（自然科学版），２０２４，４２（２）：１１２ １１７．［ＬＶＹ，ＸＵＸＷ，ＣＨＥＮＱＦ，ｅｔａｌ．ＲｅｌａｔｉｖｉｔｙａｎａｌｙｓｉｓｂｅｔｗｅｅｎｔｈｅｐｅｒｃｅｎｔａｇｅｏｆｓｅｅｄｌｉｎｇｓｉｎｔｈｅｆｉｅｌｄａｎｄｔｈｅｍｅｔｈｏｄｓｏｆｓｅｅｄｔｅｓｔｉｎｇｏｆＴａｒｔａｒｙｂｕｃｋｗｈｅａｔ［Ｊ］．ＪｏｕｒｎａｌｏｆＧｕｉｚｈｏｕＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ（ＮａｔｕｒａｌＳｃｉｅｎｃｅｓ），２０２４，４２（２）：１１２ １１７．］苦荞种子活力测定方法与其田间成苗率的相关性吕　勇，许学微，陈庆富，黄　娟，朱丽伟（贵州师范大学生命科学学院／贵州省荞麦工程技术研究中心，贵州贵阳　５５００２５）摘要：为确定与田间成苗率相关性较好的室内苦荞种子活力测定方法，以活力水平不同的４个苦荞品种：六苦１号、品苦１号、黑米１５、额曲木耳薏为试验材料。

采用标准发芽试验、低温发芽试验和高温发芽试验３种室内发芽方法测定种子活力，并将其结果与田间成苗率进行相关性分析。

结果表明标准发芽试验中，苗鲜重和活力指数与四月份田间出苗率表现出显著相关性，低温发芽试验中苗鲜重和活力指数与七月份田间出苗率表现出显著相关性，高温发芽试验中苗鲜重活力指数与四月和七月田间出苗率均表现出显著相关性。

高温发芽试验中发芽势、发芽率、苗鲜重、发芽指数、活力指数与七月份田间成苗率均表现出显著相关性，其中发芽势和发芽率与七月份田间成苗率相关系数最高（０ ９９３、０ ９０７）。

研究结论：在使用标准发芽试验检测苦荞种子活力时，苗鲜重和活力指数与田间出苗率表现出显著相关性，可作为预测田间成苗率的有效指标，逆境试验中的高温发芽试验结果与田间出苗率表现出显著相关性，可作为预测田间成苗率的有效方法。

1. alcoholn. 酒精，乙醇2. alertvt. warn (sb.) that there may be danger, trouble, etc. 使警觉，使警惕；使注意e.g. The manager alerted the staff to the crisis facing the company.3. applicationn. the action or an instance of putting a theory, discovery, etc. to practical use 应用；运用e.g. Multimedia applications usually require more computer memory and processing power.4. approximatelyad. more or less exactly; about 近似；大概approximate a. fairly correct or accurate but not completely so 近似的；大概的e.g. Approximately $150 million is to be spent on improvements of school buildings.5. as welltoo 也，又e.g. She wanted to produce the play and to direct it as well.6. automatev. (usu passive) use machines to do work previously done by people 使自动化e.g. This part of the assembly process is now fully automated.7. automobilen. a car 汽车e.g. An automobile usually has four wheels and an internal-combustion engine, used for land transport.8. boonn. a thing that is good or helpful for sb; a benefit; an advantage 特别有用的东西；好处；利益e.g. A bicycle is a real boon when you live in a small town.9. bumpern. （汽车）保险杠；减震器；缓冲器10. bunchv. group together 使成一束（或一捆等）e.g. They bunched together to allow others to squeeze into the crowded elevator.11. capabilityn. the ability or power to do sth. 能力e.g. These tests are beyond the capability of an average 12-year-old.12. computerizevt. equip with computers 使计算机化e.g. The accounts section has been completely computerized.13. convertv. (cause to) change from one form or use to another （使）转变，（使）改变e.g. Solar cooking requires a dark pot to absorb the sun's rays and convert them into heat energy.14. correlatevt. bring (sth.) into a mutual relationship (with another) 使(与…)相互关联e.g. A mother's smoking in pregnancy correlates with low birth weight in her baby.15. dashboardn. （汽车等的）仪表板16. decreasev. become or make sth. smaller or fewer 减少e.g. A single solar cooker can save a ton of firewood per year and decrease carbon dioxide emissions.17. dividern. 分开物；分隔物；分配器18. drasticallyad. 极端地；激烈地，猛力地drastic a. having a strong or violent effect 极端的；激烈的，猛力的e.g. Services have been drastically reduced.19. eliminatevt. remove (sb./sth.) that is not wanted or needed; get rid of 消除；消灭；排除e.g. The Chinese government approved a new plan to eliminate illiteracy nationwide by 2006.20. erratica. (usu derog) not regular or even in movement, quality or behavior; not reliable 不规则的，无常的；不可靠的21. expansionn. 扩大；扩展；发展e.g. Modern cosmologists are continuously calculating the age, density, and rate of expansion of the universe.22. eyelidn. 眼睑，眼皮23. fatalityn. (fml) a death caused by accident or in war, etc. （事故或战争等造成的）死亡e.g. Britain has thousands of road fatalities every year.24. frequencyn. 频率；次数；重复发生率e.g. Fatal road accidents have decreased in frequency over recent years.25. get/be stuck in (sth.)be unable to move or to be moved 停留，被阻塞e.g. I was stuck in the traffic yesterday for about one hour. That's why I missed the plane.26. grosslyad. extremely 十足；严重地gross a. glaringly obvious; whole; total 显而易见的；总的；毛的e.g. Funding of education has been grossly inadequate for years.27. hazardn. a thing that can be dangerous or cause damage; a danger or risk 危害；危险e.g. The research has confirmed that tobacco smoke presents a hazard to health.28. highwayn. 公路；交通干线e.g. Traffic along major highways in some cities is monitored by remote cameras, radar, or sensors in the roadway.29. hikern. 徒步旅行者30. hypnotica. of or producing hypnosis or a similar condition 催眠的；有催眠作用的31. in the air空气中；在空中；悬而未决e.g. There is a peculiar smell in the air.32. incorporatevt. make (sth.) part of a whole 将……包括进去e.g. His newly published book incorporates his earlier essays.33. interstatea. between states, esp. in the USA（美国）州与州之间的，州际的n. a highway between states 州际公路34. lanen. 车道e.g. The newly-built highways have two lanes for each direction of travel.35. lucrativea. producing much money; profitable 生利的，赚钱的e.g. Many ex-army officers have found lucrative jobs in private security firms.36. magnetica. 磁的；有磁性的e.g. Rubber is not magnetic.37. manufacturingn. 制造业a.制造业的，制造的manufacture vt. make (goods) on a large scale using machinery （大量）制造e.g. Britain now manufactures approximately 40 per cent of Europe's desktop computers.38. microchipn. 微芯片，微晶片39. monotonousa. dull and never changing or varying; constant and boring 单调的；一成不变的e.g. Robots are used in repetitive, monotonous tasks in which human performance might degrade over time.40. mountv. fix (sth.) in position for use, display or study; put (sth.) into place on a support 将……固定住；将……置于架上e.g. Some automobiles were designed with a transmission mounted on the rear axle.41. navigationala. 导航的，领航的42. obstructionn. a thing that is in the way of sb./sth. 障碍物obstruct v. be or get in the way of (sb./sth.); block 阻碍；阻塞e.g. John was irritated by drivers parking near his house and causing an obstruction.43. poisev. 使做好准备be poised to (do) be ready to take action at any moment 做好准备随时（做……）e.g. The automobile company is poised to launch its new advertising campaign.44. pollutionn. 污染e.g. One of the greatest challenges caused by air pollution is global warming.45. presentlyad. (esp US) now; in a short time, soon 现在，目前；不久e.g. We presently have no plans to expand our business overseas, but that may well change in the future.46. promotern. supporter of sth. 促进者；助长者e.g. an enthusiastic promoter of good causes47. prototypen. the first model or design of sth. from which other forms are copied or developed 原型；样品e.g. Bell uttered to his assistant the words, "Mr. Watson, come here; I want you," using a prototype telephone.48. quantumn. 量子49. radarn. 雷达，无线电探测器50. revolutionizevt. make (sth.) change completely or in a dramatic way 彻底改革，使发生革命性剧变e.g. Computers have revolutionized banking.51. rotationn. 旋转，转动rotate v. move or make (sth.) move in circles around a central point（使）旋转，（使）转动e.g. The Earth completes 366 rotations about its axis in every leap year.52. satelliten. 卫星e.g. Engineers have developed many kinds of satellites, each designed to serve a specific purpose or mission.53. send outtransmit (a signal, etc.) by radio waves, etc.; send from a central point 用（无线电波等）发送（信号等）；发送e.g. The yacht sent out a distress signal which was picked up by a passing steamer.54. sensorn. 传感器；探测设备e.g. A sensor is a device that converts measurable elements of a physical process into data meaningful to the computer.55. spiken. 大钉；道钉56. start upbegin or begin working, running, etc. 发动，启动；开始e.g. Peter looked in his mirror and started up the engine.57. take control of控制e.g. The new manager didn't know how to take control of his company.58. telematicsn. the branch of information technology which deals with the long-distance transmission of computerized information 远程信息学59. trafficn. movement of people or vehicles along roads or streets, of ships in the sea, planes in the sky, etc. 交通，往来60. transmittern. device or equipment for transmitting radio or other electronic signals 发射机；发报机61. trillionn. (AmE) 万亿，1012；(BrE) 百万兆，101862. turn (sth.) into/become (a) reality(使)成为现实e.g. Her dream of being a college student has turned into a reality.63. vaporn. 汽；雾；蒸汽e.g. The atmosphere always contains some moisture in the form of water vapor.64. vibratev. (cause to) move rapidly and continuously backwards and forwards; shake（使）振动，颤动，摇摆e.g. Microwave ovens operate by agitating the water molecules in the food, causing them to vibrate, which produces heat.Proper NamesMichio Kaku 米基奥·卡库Bill Spreitzer 比尔·斯普雷扎MIT abbr. Massachusetts Institute of Technology （美国）麻省理工学院GPS abbr. Global Positioning System 全球卫星定位系统Randy Hoffman 兰迪·霍夫曼Magellan Systems Corp. 麦哲伦航仪公司San Diego 圣迭戈（美国港市）。

常温超导英语Room-temperature superconductivitySuperconductivity is a phenomenon that occurs when certain materials demonstrate zero electrical resistance and can conduct electricity with 100% efficiency. However, traditional superconducting materials require extremely low temperatures, usually below -100°C, to exhibit this property.In recent years, scientists have been studying the possibility of achieving superconductivity at higher temperatures, specifically at room temperature, which would be a game-changer for a wide range of technological applications. Several research teams around the world have reported detecting superconductivity in certain compounds at temperatures above 25°C. These compounds, including hydrogen sulfide and lanthanum hydride, had previously been thought to only exhibit superconductivity at very high pressures and low temperatures.The discovery of room-temperature superconductivity could have a significant impact on areas such as power transmission, medical imaging, and transportation. For instance, if electrical wires could conduct electricity with zero resistance, a significant amount of energy could be savedduring transmission. Similarly, medical imaging techniques such as MRI would become more efficient with the use of superconducting magnets.While the research is still in its early stages, the potential for room-temperature superconductivity is exciting and could revolutionize the way we use and generate energy.。

低温热诱导相分离的英文## Low-Temperature Heat-Induced Phase Separation.Low-temperature heat-induced phase separation (LTHIPS) is a technique used to separate and purify a target protein from a mixture of other proteins. The technique is based on the principle that proteins will undergo phase separation when heated to a certain temperature. The temperature at which this occurs is known as the cloud point.LTHIPS is typically performed by heating a solution of the target protein to a temperature just below the cloud point. This causes the protein to undergo a phasetransition from a soluble to an insoluble state. The insoluble protein will then form a precipitate that can be removed from the solution by centrifugation.The cloud point of a protein is determined by a number of factors, including the protein's concentration, the pH of the solution, and the presence of other solutes. Thecloud point can also be affected by the rate at which the protein is heated.LTHIPS is a versatile technique that can be used to purify a wide range of proteins. The technique isrelatively simple to perform and can be scaled up to produce large quantities of purified protein.### Applications of LTHIPS.LTHIPS has a number of applications in the field of protein science. The technique can be used to:Purify proteins LTHIPS can be used to purify proteins from a variety of sources, including cells, tissues, and fermentation broths. The technique is particularly useful for purifying proteins that are difficult to purify by other methods.Fractionate proteins LTHIPS can be used to fractionate proteins based on their solubility. This can be useful for separating proteins that have similar properties but differin their solubility.Study protein interactions LTHIPS can be used to study protein interactions by examining the changes in the cloud point of a protein in the presence of other proteins. This can be useful for identifying proteins that interact with each other and for determining the strength of these interactions.Develop new protein-based materials LTHIPS can be used to develop new protein-based materials by exploiting the ability of proteins to undergo phase separation. These materials could have applications in a variety of fields, including medicine, biotechnology, and nanotechnology.### Advantages of LTHIPS.LTHIPS has a number of advantages over other protein purification methods. These advantages include:Simplicity LTHIPS is a relatively simple technique to perform. The technique does not require specializedequipment or reagents.Scalability LTHIPS can be scaled up to produce large quantities of purified protein. This makes the technique suitable for use in industrial applications.Versatility LTHIPS can be used to purify a wide range of proteins. The technique is not limited to specific types of proteins or sources.Low cost LTHIPS is a relatively low-cost technique to perform. The reagents and equipment required for the technique are inexpensive.### Limitations of LTHIPS.LTHIPS also has some limitations. These limitations include:Yield The yield of LTHIPS can be variable. The yieldis often lower than that of other protein purification methods.Purity The purity of LTHIPS can also be variable. The technique can sometimes produce protein that is contaminated with other proteins.Denaturation LTHIPS can sometimes denature proteins. This can be a problem if the protein is required to be active for its intended application.### Conclusion.LTHIPS is a versatile technique that can be used to purify, fractionate, and study proteins. The technique is relatively simple to perform and can be scaled up to produce large quantities of purified protein. LTHIPS has a number of advantages over other protein purification methods, but it also has some limitations.。

5.5An apparatus specially designed for the TR test 3,4isschematically illustrated in Fig.1.The sample rack is shown onthe left,and the over-all assembly on the right.The bathconsists of an unsilvered Dewar flask that is contained in aninsulating wooden frame,0.The frame contains a wide slot infront,through which the test can be observed and the tempera-tures read.Other details of the apparatus are given in Section8.6.Test Specimens6.1The test specimens may be prepared by dieing out witha die of the design shown in Fig.2.The choice of die length isgoverned by the elongation required and the limitations of thespecimen racks.For most work a 38mm (1.50in.)die is suitable.Thickness of the specimens shall be 2.060.2mm (0.0860.01in.).Any other method of obtaining test speci-mens of uniform cross section is satisfactory,provided that a suitable clamp is used on the rack.6.2Three specimens per material shall be tested.7.Initial Specimen Extension 7.1The initial extension (elongation)of specimens to be tested should be chosen with the following considerations:7.1.1To study the effect of crystallization at low tempera-tures use a value of either:(1)250%,(2)half the ultimate elongation if 250%is unobtainable,or (3)350%if the ultimate elongation is greater than 600%.7.1.2To avoid the effect of crystallization,use an elongation of 50%.7.2For long exposures,the 50%elongation may be used in combination with a conditioning procedure,in accordance with Practice D 832.In such studies,crystallization of the long-time conditioned specimen is indicated by the displacement of the TR curve toward the higher temperature.Tests conducted at 50%elongation without previous long-time conditioning have been found to correlate fairly well with stiffness tests.8.Procedure 8.1Fill the bath,N (Fig.1)to within about 50mm (2in.)of the top with methanol.Start the stirrer,P .Cool the methanol by dipping into it,for short intervals,a wire cage filled with chopped dry ice.Care must be employed at the beginning of this operation to prevent excessive frothing.When the tem-perature drops to −70°C (−94°F)chopped dry ice can be added directly to the methanol.8.2Insert one end of the test specimen,B ,in the stationary clamp,C 1,at the bottom of the sample rack,A ,and the other end in the movable clamp,C .Stretch to the length desired,reading the length by means of the indicator,E ,attached to the connecting wire,F ,and moving over the graduated scale,G .Anchor the specimen in the elongated position by tightening the thumb nut,D .Adjust the flexible cord,H ,that is attached to the wire,F ,at one end and to a counterweight at the other end,so that it moves freely over the pulley,I .(The counter-weight should be 3to 5g heavier than the clamp and wire that it counterbalances.)Repeat this operation for the other speci-mens in the rack.Insert the thermometer,K ,in the holder,L .8.3Place the rack,A ,in the bath.This must be done slowly to avoid frothing.Tighten the thumb nuts,that anchor the rack support,M ,to the bath.8.4If the temperature of the batch rises above −70°C (−94°F)when the rack is inserted,add a little dry ice to reduce the temperature to between −70and −73°C.8.5Let stand 10min,then release the thumb nuts,D ,and allow the specimens to retract freely.8.6Turn on the heater,R ,and maintain a temperature rise of 1°C/min (2°F/min)by adjusting the rheostat.3A modified Scott T-50tester has been used by some investigators.See Svetlik,J.F.,and Sperberg,L.R.,“The T-R (Temperature Retraction)Test Characterizingthe Low-Temperature Behavior of Elastomeric Compositions,”India Rubber World ,May,1951,p.182.4See Smith,O.H.,Hermonat,W.A.,Haxo,H.E.,and Meyer,A.W.,“RetractionTest for Serviceability of Elastomers at Low Temperatures,”Analytical Chemistry ,V ol 23,1951,p.322.FIG.1RetractionApparatusFIG.2Die for Preparing TestSpecimens8.7Take thefirst reading at−70°C(−94°F),and continue to read the length at2min intervals until retraction is75% completed.N OTE1—When one standard specimen length and initial elongation are maintained,temperatures at which specific degrees of retraction occur may be read directly.8.8If a methanol-dry ice system does not produce tempera-tures low enough to freeze the specimens to practically a nonelastic state,then other cooling media may be employed.9.Calculations9.1Calculate retraction values at any specific temperature as follows:retraction,%5@~L e2L t!/~L e2L o!#3100(1) where:L o5length of specimen in the unstretched condition,L e5length of specimen in the stretched condition,andL t5length of specimen at the observed temperature.9.2Calculate the temperature at any specific retraction as follows:9.2.1Determine the length of the test specimen at the desired retraction L r,by means of the following formula:L r5L e2~%retraction/100!~L e2L o!(2) 9.2.2Note the nearest temperature corresponding to the length,L r,and determine the exact temperature by interpola-tion.10.Report10.1Report the following information:10.1.1The median values of the following:10.1.1.1Testing elongation,in percent.10.1.1.2Temperatures at which the specimen retracts10, 30,50,and70%.These temperatures shall be designated, respectively,as TR10,TR30,TR50,and TR70.10.1.1.3Difference between TR10and TR70in degrees celsius.10.1.2The method or equipment used to measure tempera-ture(glass thermometer,thermocouple,etc.).10.1.3Length of the test specimens before elongation. 10.1.4Time and temperature of initial conditioning.10.1.5Rate of temperature rise,and10.1.6Coolant used.11.Precision and Bias511.1This precision and bias section has been prepared in accordance with Practice D4483.Refer to this practice for terminology and other statistical calculations details.11.2A Type1(interlaboratory)precision was evaluated in 1985.Both repeatability and reproducibility are short term,a period of a few days separates replicate test results.A test result is the mean value,as specified in this test method,obtained on two determination(s)or measurement(s)of the property or parameter in question.11.3Five different materials or compounds were used in the interlaboratory program,these were tested in two laboratories on two different days.One of the laboratories had two different operators perform the testing so that a total of three different operators were involved.The statements are based on the testing offive compounds by three operators on two days. 11.4Standard vulcanized sheets were prepared by the sup-plying laboratory.Each participant die cut the test specimens.A test result is defined to be the average of two separately prepared specimens.Precision statements were prepared for TR10,30,50,70,and(70-10)where each operator determined test results in accordance with Section9.11.5Within laboratories,S r values of zero were obtained for S r for selected parameters for several of the test compounds. These values are to no variation between the results obtained on two different test days by any of the three operators. 11.6Due to the occurrence of zero values for S r,the values of S r(and S R)were pooled for TR levels(10to70)and for materials.This was done to obtain a better estimate of the true S r(and S R)for the expression of precision.A tabulation of the S r and S R values and the results of the pooling calculations is given in Table1.With the exception of Material1,the values of S r and S R are essentially constant for the other four materials.Based upon this the general precision for TR values (10to70)is given in Table2.11.7The precision for the difference in TR(70-10)is given in Table3.The precision of this test method may be expressed in the format of the following statements that use what is called an appropriate value of r,R,(r),or(R),that is,that value to be used in decisions about test results(obtained with the test method).The appropriate value is that value of r or R associated with a mean level in the precision tables closest to the mean level under consideration at any given time,for any given material in routine testing operations.11.8Repeatability—The repeatability r,of this test method has been established as the appropriate value tabulated in the precision tables.Two single test results,obtained under normal test method procedures,that differ by more than this tabulated r(for any given level)must be considered as derived from different or non-identical sample populations.5Supporting data are available from ASTM Headquarters.Request RR:D11-1037.TABLE1Pooling of Within Laboratory S r and BetweenLaboratory S RMaterial or S r:Compound TR10TR30TR50TR70Pooled,S rMean TR Value,°K(°C)10.00.00.00.200.10264.4(−8.6)20.00.200.820.200.437235.3(−37.8)30.820.00.610.00.511241.0(−32.0)40.200.00.200.820.434235.8(−37.3)40.00.610.610.840.602240.6(−32.8) Pooled S r0.3780.2870.5400.540(0.450)S R:Material TR10TR30TR50TR70Pooled,S RMean TR Value,°K(°C)1 1.010.760.640.180.714264(−8.6)27.30 5.70 1.040.90 4.68235.3(−37.8)30.25 2.38 4.26 6.71 4.15241.0(−32.0)4 2.060.790.88 1.54 1.415235.8(−37.3)50.060.830.73 1.370.881240.6(−32.8) Pooled S R 3.42 2.83 2.05 3.17(2.914)11.9Reproducibility —The reproducibility R ,of this testmethod has been established as the appropriate value tabulatedin the precision tables.Two single test results obtained in twodifferent laboratories,under normal test method procedures,that differ by more than the tabulated R (for any given level)must be considered to have come from different or non-identical sample populations.11.10Repeatability and reproducibility expressed as a per-centage of the mean level,(r )and (R ),have equivalent application statements as above for r and R .For the (r )and (R )statements,the difference in the two single test results is expressed as a percentage of the arithmetic mean of the two test results.(See,however,the caveat statement,a footnote in Table 3on (r )and (R )for TR (70-10).)11.11Bias —In test method terminology,bias is the differ-ence between an average test value and the reference (or true)test property value.Reference values do not exist for this test method since the value (of the test property)is exclusively defined by the test method.Bias,therefore,cannot be deter-mined.12.Keywords12.1crystallization;low temperature retraction;rubber;viscoelastic properties The American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this ers of this standard are expressly advised that determination of the validity of any such patent rights,and the risk of infringement of such rights,are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised,either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM Headquarters.Your comments will receive careful consideration at a meeting of the responsible technical committee,which you may attend.If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards,100Barr Harbor Drive,West Conshohocken,PA 19428.TABLE 2Type 1Precision (TR 10to TR 70)N OTE 1—S r 5within laboratory standard deviation.r 5repeatability (in measurement units).(r)5repeatability (in percent).S R 5between laboratory standard deviation.R 5reproducibility (in measurement units).(R)5reproducibility (in percent).Material(Compound)Mean TR Value Within Laboratories Between Laboratories °K °C S r r r A S r r (R )A 1264.4(−8.6)0.100.280.110.713 2.020.772235.3(−37.8)0.437 1.240.53 4.6813.20.563241.0(−32.0)0.511 1.450.60 4.1511.70.494235.8(−37.3)0.434 1.230.52 1.42 4.02 1.705240.6(−32.8)0.602 1.700.710.881 2.49 1.03Pooled (Mean)Value:243.3(−29.7)0.450 1.270.52 2.9148.25 3.40A Mean TR in °K used.TABLE 3Type 1Precision TR (70-10),°KN OTE 1—S r 5within laboratory standard deviation.r 5repeatability (in measurement units).(r)5repeatability (in percent).S R 5between laboratory standard deviation.R 5reproducibility (in measurement units).(R)5reproducibility (in percent).Material Mean Level,TR(70-10),°KWithin Laboratories Between Laboratories S r r (r )A S R R (R )A 17.90.200.577.10.88 2.4935.1231.30.200.57 1.88.0922.97.33180.82 2.3212.9 6.9219.6109.413.20.61 1.7313.1 3.5810.176.5540.50.85 2.38 5.9 1.41 4.09.9Pooled (Mean)Value:22.20.605 1.7127.7 5.0814.464.9A The relative (%),(r )and (R )are given,but these must be interpreted with caution due to the often near zero temperature difference values of TR(70-10).。