制药工程论文英文文献翻译
醋酐
马克路易斯
（商业化学药品评估部门加拿大 351圣约瑟林荫大道）
[摘要]介绍了醋酐的性质，在北美制造的两个程序及对环境、人类健康的影响。
[关键词]醋酐纤维素分解
1 性质
分子的公式：C4H6O3
结构的公式：（CH3CO）2O
分子的重量：102.09
沸腾的点（760 mmHg）：138.6℃（282℉）
冰点：-73℃（-100℉）
2 在暴露上的一般资讯
2.1 一般的讨论
醋酐在北美被制造二个程序。大部份的生产使用ketene－醋酸技术，包括对 ketene 的热很快的醋酸和那用形成醋的醋酐另外的醋酸的后来反应。甲基醋酸盐是第二条路径。一些醋的酸在甲基中当做一种共同产品被生产醋酸盐处理[1]。
醋酐在制造业的醋酸盐酯中用当做一个试药，醋酐的反应用氢氧基小组产生对应的醋酸盐酯与醋酸。醋酐是二手的使乙醯化对阿斯匹林方面的得自水杨酸的酸。大部份的醋醋酐生产被消耗在制造业的纤维素醋酸盐酯。纤维素醋酸盐酯包括纤维素和混合的酯。在纤维素醋酸盐的产品中，小组从每个醋的醋酐分子与纤维素起化学反应，而且另一个小组被转换到醋的酸哪一个能向后地被使再循环制造更多的醋醋酐或者被用来生产其他的醋酸引出之物。过滤器是从拖和可塑剂的一种混和制造，纤维素醋酸盐细丝纱被用于衣服和回家家具。纤维素被用于照相的电影而且强迫敏感的音带。
2.2 生产释放
这些释放全部是对气氛，浇水的任何释放诉诸于注入，适当的到这会只是礼物的水解和可发觉的当做醋的酸，任何的释放以这一样子是期望是最小的。
2.3 使用的释放
2.3.1 从纤维素醋酸盐生产释放
主要的下游使用在纤维素醋酸盐生产，哪里醋的醋酐是一中间物。释放编号给予的在2.2年，是给 Celanese 加拿大爱德蒙顿设备整体而言，和如此包括生产和使用。虽然没有限定的数字是可得的，但是给性质纤维素醋酸盐程序任何的排放物预期很小的（<10%的总计排放物）和由于水解，以醋酸的形式。
2.3.2 消费者的释放使用
醋酐被当作反动的中间物使用。当反应，举例来说制造纤维素醋酸盐，它不在使用被再产生。因为它是反动的而且不迟疑地加水分解，它的出现在结束使用的产品是不可能的。为较进一步的数据见到第4.1.2节。
2.3.3 广大的释放
一般的广大释放不是醋酐的一个可适用情节。它只被用当做一俘虏，反动的中间物。
2.4 关于安全的处理资讯
如果意外释放，点火来源应该被除去。泄漏容器应该是用溢出包含放在一个通风的良好区域之内。如果火潜能存在，总括性的溢出与酒精－类型水的形成电影的泡沫或使用水喷雾驱散蒸汽。扫除方法可能包括能吸收材料或一个真空卡车的使用。表面流水进入暴风雨下水道和沟渠之内哪一个领引对天然的航路应该因溢出包含而避免。醋醋酐容器的储藏应该与适当的通风和容器当不在使用中的时候，应该被关闭。连络用眼睛、皮肤或衣服，而且呼吸醋的醋酐蒸汽应该被避免。被弄脏的衣服应该以前被彻底地净化关于－使用和受污染的皮革衣服应该被破坏。工人应该彻底地洗藉由肥皂和水在处理醋的醋酐容器之后。醋的醋酐应该从热、火花和火焰来源被储存，而且不应该是以不相容的材料储存。不相容的材料包括水；水的碱如此的当做腐蚀剂苏打解决；酒精；乙二醇；氢、酸、氮的酸，铬三氧化物、和其他的氧代理人；胺；硼酸。醋的醋酐与水起化学反应形成醋的酸和热。
3 环境
3.1 环境的暴露
3.1.1 一般的讨论
在天然的水域中，醋酐对的第一次序反应根据加水分解醋的酸。根据实验式地决定的比率常数[2]，一能计算一半－生命，t1\2，4.4 分钟，在 25℃和8.1 分钟。对醋酸降格也在气氛下发生。根据一实验式地决定了比率常数，为醋酸的完成反应的降格与光化学地形成急进份子在22天的一半－生活已经被计算的气氛下[3]。然而，因为它的高可溶性，醋的酸将会快速地被洗掉那气氛。在生物降解能力的静态测试中，醋酸是被降级的至超过95%
在5天[4]。在再肺活量计测试（在修正的 MITI 测试中的22～24小时）醋的酸中是被降级的到99%[5]。对于醋的醋酐一个水的分割系数，记录 Pow，-0.27 已经被计算，当为醋的酸，记录-0.17 Pow 已经被实验式地决定的时候[6-7]。两者皆不的价值为生物体内蓄积提供潜能的任何指示。
3.1.2 被预测的环境的集中
给每年被释放到气氛定态州的醋酐的体积使用易逃逸模型作为北方亚伯达的区域的
集中能是估计[8]。释放至这一378 000公里2个区域在空气中造成2.4 x 10-15 毫克│m3，2.33 x 10-9 μg│g 在土壤，在水中的 1.8 x 1.11 克│m3，和在沉淀物的 1.9 x 1.14 克│m3在空气中假定住宅时间2.42为这一个区域的在水中的数天和75.1天。全部的反应持续在0.107点被估计hrs。对于水的集中能被当作计算的 PEC 使用（也就是 PEC ＝ 1.7 x 10-11毫克│L）。当做先前注意，醋酐的副产物是醋的酸。它很快地是和不。（伐木 Pow ＝ -0.17）它在类似的水生种方面是比较不有毒超过醋酐和以它的被使中立的形式（醋酸盐）它在新陈代谢方面扮演重要角色所有的种。
3.2 对环境的效果
各种不同实验室的结果以水生的生物测试[9]，在哪一个有毒的门槛对于醋的醋酐集中为醋的酸被发现是有关一半那些，建议一开始的有毒效果，只要不是所有的那都已经加水分解到醋的酸（在第一个期间几分钟）[10]。
3.3 起始评估为环境
要决定 PNEC，18 毫克│L 的慢性最低效果水平被采取而且分开的2到获得从经济合作暨发展组织 SIDS 手册被基于指导的9的被估计的 NOEC 毫克│L（六月1997)[11]。应用一个100安全因素（因为慢性的 NOECs 不是另一个可以使用营养的水平）提供0.09的 PNEC 毫克│L。因为慢性的 NOECs 不是可得对水蚤或鱼一个比较一定在起源于的 PNEC 之间被做最低的敏锐的价值[12]。最低的敏锐效果水平正在给在55毫克│L。的水蚤应用一个500安全因素因为慢性的数据可用来[13]，藻类和物质不是固执给0.11 PNEC些微地比起源于慢性的数据的 PNEC 高的毫克│L。
4 人类的健康
4.1 人类的暴露
4.1.1 职业的暴露
OSHA PEL，MAK 价值和 ACGIH TLV 为醋酐现在是5个百万分之一。内在的和 Celanese 加拿大工作地点暴露水平（WEL）是1个百万分之一。在一典型的醋酸酐生产那里的设备是
少于100工人。基于工业的卫生保健监听数据在 Celanese 加拿大爱德蒙顿获得植物而且在 Hoechst Celanese 美国植物，吸入暴露在下面被公开和内在的工作地点暴露指导方针[14]。这应用两者都对醋的醋酐生产和主要的使用（纤维素醋酸盐生产）。工业的卫生保健监听的特定的数据记录在 Celanese 加拿大爱德蒙顿厂（醋的醋酐和纤维素醋酸盐生产）是提供了下一个。最时常暴露已经被藉由在空气中测量醋的酸集中检测[15]。那方法有少于0.1个百万分之一的一个发现的界限。基于110空气样品测量每一在过去六年上的年，在各种不同的工作种类中以对醋的醋酐暴露，工人是暴露90％时候至少于0.1～0.4个百万分之一。Hoechst Celanese 和 Celanese 加拿大发展了和定相现在在较新的方法学中对于特定的醋醋酐监听以0.07个百万分之一的一个发现的界限。在 Hoechst 的结果Celanese 美国设备是类似的至先前为 Celanese 加拿大被讨论的那些[16]。为例子在去年之上，使用被指出的新的方法 70个空气样品测量醋的醋酐水平在范围中：＜至 0.35个百万分之一的0.07个百万分之一（发现的界限）。水平在大部分方面样品在发现的界限下面。皮肤、口头的暴露不被预期是暴露的重要路径在标准的职业练习，因为给予保护程序和设备用[17]。
4.1.2 其他的暴露情节
作为完全地在被加倍的使用被反应的俘虏中间物的给予醋酐使用藉由它的非常短一
半－生活，消费者或广大的环境暴露情节是不有可能的。两者皆不的 Celanese 加拿大，唯一的加拿大制造业者，也不 Celanese 化学药品区分，最大的美国生产者之一为消费者申请卖醋的醋酐。醋醋酐的欧洲制造业者被质疑了关于对消费者讲的申请售卖，但是没有为消费者申请指出售卖。注意很重要醋的醋酐售卖紧紧地被控制和被记录的结束使用被制造业者在规则之下避免对违法的药物综合的化学转移。那国际的数据摘要为醋的醋酐在SRI 化学的经济学手册中没有为醋的醋酐提到任何的消费者申请或市场。基于这最近者输入，没有指示它的使用大体上在消费者中国际性地是练习工业[18]。
4.2 对人类的健康效果
在有关的文件准备期间被识别的开始的数据缝隙是：次慢性的毒性，生殖的毒性和在活泼的诱变性中。基于醋醋酐的身体的│化学特性，它的新陈代谢产物（醋的酸）加上数据从一次慢性的吸入│生殖的毒性研究，测试计画然后讨论在暹逻1995年二月被呈现在威廉斯堡见面，维吉尼亚而且核准。在男性中的一项90天的次慢性的吸入研究而且有着另外的90天的恢复的女性鼠逐步运行估定被提供的可反转性那为计画的基础。也被包括在内的是广泛又显微镜评估那生殖的器官加骨髓的标准分析。结果被描述在相关的区段中的下一个。
4.2.1 独身者暴露
可接受质量的没有皮肤促进感受性研究是可得的。在一项 1940 的研究中使用注入，
要求的一个回应促进感受性反应是指示的是为在橄榄油中受到25%解决的天竺鼠报告。给腐蚀性质醋的醋酐，与动物福利考量一起加倍，促进测试会是困难的证明[19]。
4.2.2 重复的暴露
一项使用在动物中的吸入路径的早的研究极少被报告和不确定的有效性[20]。不够的细节从这一项报告是可得的拉可靠的对醋的醋酐关于重复吸入暴露的效果的结论。因此，新的吸入研究被引导了。
4.3 起始评估为人类的健康
4.3.1 职业的（工人）
最低的 NOEL，1个百万分之一（4.2 毫克│m3），经由最有关的以一项最近的次慢性的研究为基础暴露路径吸入。在 LOEL 5个百万分之一（21 毫克│m3），最小、可逆的呼吸器官的广阔的地面刺激被观察了，但是没有系统的毒性。在活泼的中和发展上的毒性研究没有揭露在较高的集中（20～25个百万分之一）的特性效果。工作地点暴露监听从植物，数据是可得的产生醋的醋酐而且从植物使用它。暴露水平是低的因为程序和设备加上工人训练计划适当地提供保护。因此，醋的醋酐被考虑低潜能为为危险配备人手的。
4.3.2 另外地
给它的使用式样（俘虏中间物，完全地反应在使用）和迅速的水解。非人类研究的25℃）对正常的身体新陈代谢产物（醋酸盐），消费者或广大的环境暴露是不人类的暴露的重要的情节到醋的醋酐。
5 结论及忠告
5.1 环境
醋酐为它完全地的化学的综合被独自地当做中间物用反应了。在水圈中，醋的醋酐快速地被加水分解一半到醋的不迟疑可自然腐化的酸。在气氛下，它被转换到醋的酸是依照降格。一半－生活 22 天对水生的生物毒性是适度的（18-3400 毫克│L），但是由于它的迅速水解它对醋酸盐│醋的只坚持短时间酸。它为生物体内蓄积事实上没有潜能。（记录 Kow ＝-0.27)PEC│PNEC 比是更较少的超过一（1.9 x 10-10）。因此，醋酐为暴露有低的潜能而且是考虑现在对 SIDS 背景的进一步的环境工作低优先。
5.2 人类的健康
对于醋的醋酐紧要关头的效果连络在现场是刺激[21]。因为它众所周知的腐蚀的而且对眼睛，皮肤和呼吸器官的广阔地面和低的气味门槛的刺激效果，程序、设备（举例来说，护目镜、手套，口罩），训练和工程控制有已经适当地许多年避免暴露。工业的卫生保健
监听数据指出，醋酐的水平在1个百万分之一下面8hr的。时间－重量－平（4.2 毫克│m3）在醋酐被生产的设备和醋酐的主要使用拿的地方中地方。醋酐被独有地当做化学的中间物用，而且没有指示它的使用大体上是在消费者业中的练习。一般建议职业的暴露极限被再访基于在这一 SIAR 中被报告的另外的测试。醋酐被考虑为了SIDS 背景的比较进一步的讲健康的工作现在是低优先。
参考文献
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Acetic Anhydride
Mark Lewis
(Commercial Chemicals Evaluation Branch , Canada , 351 St. Joseph Boulevard)
[Abstract]Introduced the property of acetic anhydride , two procedures for making in North Amer-
ica and to the environment , influence with healthy mankind.
[Keywords] acetic anhydride；the cellulose；resolve
1 IDENTITY
Molecular Formula: C4H6O3
Structural Formula: (CH3CO)2O
Molecular Weight: 102.09
Boiling point (760 mmHg): 138.6°C (282°F)
Freezing point: -73°C (-100°F)
2 GENERAL INFORMATION ON EXPOSURE
2.1 General Discussion
Acetic anhydride is manufactured in North America by two processes . Most of the production uses the ketene - acetic acid technology , Some acetic acid is produced as a co- product in the methyl acetate carbonylation process(1) . Acetic anhydride used as a reagent in manufacturing acetate esters , acetylation of pharmaceuticals, end-capping polyacetal homopolymers , and other reactions is consumed in the reaction step .
Reactions of acetic anhydride with hydroxyl groups yield the corresponding acetate ester with coproduction of acetic acid. Acetylation of amines produce acetamides such as TAED (tetraacetylethylenediamine) , which is used as a perborate bleach activator . Acetic anhydride is used to acetylate salicylic acid to aspirin and p-aminophenol to acetaminophen . In the manufacture of cellulose acetate , one acetyl group from each acetic anhydride molecule reacts with the cellulose and the other acetyl group is converted to acetic acid which can be recycled back to make more acetic anhydride or be used to produce other acetic acid derivatives . Shredded pure alpha cellulose is typically soaked in aqueous acetic acid before the treated pulp is acetylated with a 60-40 mixture of acetic acid and acetic anhydride using a dilute sulfuric acid catalyst . Cellulose acetate fibers are recovered as tow or as filament yarn . Filters are made from a blend of tow and plasticizer. Cellulose acetate filament yarns are used in apparel and home
furnishings . Cellulose triacetate is used in photographic film and pressure sensitive tapes .
2.2 Production releases
These releases are all to the atmosphere . Any release to water goes to deepwell injection. Due to hydrolysis this would only be present and detectable as acetic acid . Any releases in this manner are expected to be minimal .
2.3 Release from use
2.3.1 Release from cellulose acetate production
The major downstream use is in Cellulose Acetate Production , where Acetic Anhydride is an intermediate . The release numbers given in 2.2. are for the Celanese Canada Edmonton facility as a whole , and so include both production and use . Although no definitive numbers are available , given the nature of the Cellulose Acetate Process any emissions are expected to be small (<10% of total emissions) and due to hydrolysis , in the form of acetic acid .
2.3.2 Release from consumer use
Acetic anhydride is used as a reactive intermediate . When reacted, for example to make cellulose acetate , it is not regenerated in use . Because it is reactive and readily hydrolyzed , its presence in end use products is not possible . See Section 4.1.2 for further information .
2.3.3 Widespread release
General widespread release is not an applicable scenario for acetic anhydride . It is used only as a captive , reactive intermediate .
2.4 Information on Safe Handling
In case of accidental release , ignition sources should be eliminated . Leaking containers should be placed in a well-ventilated area with spill containment . If fire potential exists , blanket spill with alcohol-type aqueous film-forming foam or use water spray to disperse vapors . Clean-up methods may include use of absorbent materials or a vacuum truck . Runoff into storm sewers and ditches which lead to natural waterways should be avoided by spill containment . Storage of acetic anhydride containers should be with adequate ventilation and the containers should be closed when not in use . Contact with eyes, skin or clothing , and breathing acetic anhydride vapor should be avoided. Soiled clothing should be decontaminated thoroughly before re-use and contaminated leather clothing should be destroyed . Workers should wash thoroughly with soap and water after handling acetic anhydride containers .
Acetic anhydride should be stored away from heat , sparks , and flame sources , and should not be stored with incompatible materials . Incompatible materials include wate ; aqueous alkalis such as caustic soda solution ; alcohols ; glycols ; hydrogen peroxide , perchloric acid , nitric
acid , chromium trioxide , and other oxidizing agents ; amines ; boric acid . Acetic anhydride reacts with water to form acetic acid and heat .
3 ENVIRONMENT
3.1 Environmental Exposure
3.1.1 General Discussion
In natural bodies of water, acetic anhydride hydrolyses according to a first-order reaction to acetic acid . On the basis of experimentally determined rate constants (2) , one can calculate
half-lives , t1/2 , of 4.4 min. (at 25°C) and 8.1 min . (at 15°C) . This hydrolytic degradation to acetic acid also occurs in the atmosphere . On the basis of an experimentally determined rate constant , for the degradation of acetic acid through reaction with photochemically formed
OH-radicals in the atmosphere a half-life of 22 days has been calculated (3). However , on account of its high solubility , acetic acid will be rapidly washed out of the atmosphere . In the static Zahn-Wellens test of biodegradability , acetic acid is degraded to more than 95% within 5 days (4) . In the respirometer test (22 - 24 hours in modified MITI test) acetic acid is degraded to 99% (5) .
For acetic anhydride an n-octanol/water partition coefficient , log Pow , of -0.27 has been calculated , while for acetic acid a log Pow of -0.17 has been experimentally determined (6,7) . Neither value gives any indication of a potential for bioaccumulation .
3.1.2 Predicted Environmental Concentration
Given the volume of acetic anhydride released to the atmosphere annually the steady state concentrations using Mackay fugacity model ChemCan IV for the region of northern Alberta can be estimated . Releases to this 378 000 km2 area result in 2.4 x 10-15 mg/m3 in air, 2.33 x 10-9 μg/g in soil , 1.8 x 10-11 g/m3 in water , and 1.9 x 10-14 g/m3 in sediment assuming a residence time in air of 2.42 days and 75.1 days in water for this region . Overall reaction persistence is estimated at 0.10 hrs(8) . The concentration for water can be used as a PEC in the calculation (i.e. PEC = 1.7 x 10-11 mg/L) . As previously noted, the by-product of acetic anhydride is acetic acid . It is quickly biodegraded and does not bioaccumulate (log Pow = -0.17). It is less toxic in comparable aquatic species than acetic anhydride and in its neutralized form (acetate) it plays an important role in the metabolism of all species(9) .
3.2 Effects on the Environment
The results of various laboratory tests with aquatic organisms , in which the toxic threshold
concentrations for acetic anhydride were found to be about half those for acetic acid, suggest an initial toxic effect , so long as not all of the substance has hydrolyzed to acetic acid (during the first few minutes) .
3.3 Initial Assessment for the Environment
To determine the PNEC , the chronic lowest effect level of 18 mg/L is taken and divided by 2 to obtain an estimated NOEC of 9 mg/L based on guidance from the OECD SIDS Manual (June 1997) . Applying a safety factor of 100 (because chronic NOECs are not available for the other trophic levels) provides a PNEC of 0.09 mg/L . Because chronic NOECs are not available for Daphnia or fish a comparison must be made between the PNEC derived from the lowest acute value . The lowest acute effect level is for Daphnia at 55 mg/L(10) . Applying a safety factor of 500 because chronic data is available for algae and the substance is not persistent gives
a PNEC of 0.11 mg/L which is slightly higher than the PNEC derived from chronic data(11) .
4 HUMAN HEALTH
4.1 Human Exposure
4.1.1 Occupational Exposure
The OSHA PEL , MAK value and ACGIH TLV for acetic anhydride is currently 5 ppm (8-hr. TWA) . The internal Hoechst Celanese and Celanese Canada Workplace Exposure Level (WEL) is 1 ppm (8-hr. TWA) . In a typical acetic anhydride production facility there are fewer than 100 workers . Based on industrial hygiene monitoring data obtained at the Celanese Canada Edmonton plant and at the Hoechst Celanese U.S . plants , inhalation exposure is below published and internal workplace exposure guidelines(12) . This applies both to acetic anhydride production and the major use (cellulose acetate production) . Specific information from industrial hygiene monitoring records at the Celanese Canada Edmonton Plant (acetic anhydride and cellulose acetate production) is provided next .
Most often exposure has been monitored by measuring acetic acid concentration in the air . The method has a limit of detection of less than 0.1 ppm . Based on 110 air sample measurements per year over the last six years(13) , in various job categories with exposure to acetic anhydride , workers were exposed 90 m% of the time to less than 0.1 to 0.4 ppm . Hoechst Celanese and Celanese Canada developed and are currently phasing in newer methodology for specific acetic anhydride monitoring with a limit of detection of 0.07 ppm . Results at Hoechst Celanese U.S. facilities are comparable to those previously discussed for Celanese Canada(14) .
For example over the last year , using the new method 70 air sample measurements indicated acetic anhydride levels were in the range: < 0.07 ppm (limit of detection) to 0.35 ppm . Levels in most of the samples (15) were below the limit of detection. Dermal and oral exposure would not be anticipated to be significant routes of exposure under standard occupational practice , because of protective procedures and equipment used(16) .
4.1.2 Other Exposure Scenarios
Given acetic anhydride’s use as a captive intermediate which is completely reacted in use coupled with its very short half-life , consumer or widespread environmental exposure scenarios are not likely(17) . Neither Celanese Canada , the sole Canadian manufacturer , nor the Celanese Chemicals Division , one of the largest U.S. producers, sell acetic anhydride for consumer applications . European manufacturers of acetic anhydride (BP , Hoechst and Wacker-Chemie) were queried regarding sales to consumer-related applications , but indicated no sales for consumer applications . It is important to note that acetic anhydride sales are tightly controlled and end uses recorded by manufacturers under regulations to prevent chemical diversion to illegal drug synthesis . The International Data Summary for Acetic Anhydride in the SRI Chemical Economics Handbook did not mention any consumer applications or markets for acetic anhydride(18) . Based on this recent input, there is no indication that its use is in general practice internationally in the consumer industry .
4.2 Effects on Human Health
The initial data gaps identified during dossier preparation were: subchronic toxicity , reproductive toxicity and in vivo mutagenicity . Based on the physical/chemical properties of acetic anhydride , its metabolite (acetic acid) plus data from a subchronic inhalation/reproductive toxicity rangefinding study , the testing program discussed next was presented at the February , 1995 SIAM Meeting in Williamsburg , Virginia and approved . A 90-day subchronic inhalation study in male and female rats with an additional 90-day recovery phase to assess reversibility provided the foundation for the program . Also included was a comprehensive , microscopic assessment of the reproductive organs plus standard cytogenetic analysis of the bone marrow. Results are described next in the pertinent sections .
4.2.1 Single exposure
No skin sensitization studies of acceptable quality are available . In a 1940 study using intracutaneous injection, a response claimed to be indicative of sensitization reaction was reported for guinea pigs receiving a 25% solution in olive oil . Given the corrosive nature of
acetic anhydride , coupled with animal welfare considerations , further testing would be difficult to justify (19) .
4.2.2 Repeated exposure
One early study (20) using the inhalation route in animals was poorly reported and of uncertain validity . Insufficient detail was available from this report to draw reliable conclusions about the effects of repeated inhalation exposure to acetic anhydride . Therefore , new inhalation studies were conducted .
4.3 Initial Assessment for Human Health
4.3.1 Occupational (Workers)
The lowest NOEL , 1 ppm (4.2 mg/m3) , is based on a recent subchronic study via the most relevant exposure route , inhalation . At the LOEL , 5 ppm (21mg/m3), minimal and reversible respiratory tract irritation was observed , but no systemic toxicity . In vivo genotoxicity and developmental toxicity studies did not reveal specific effects at higher concentrations (20-25 ppm) . Workplace exposure monitoring information is available from plants producing acetic anhydride and from plants using it . Exposure levels are low because procedures and equipment plus worker training programs are in place which provide protection. Therefore , acetic anhydride is considered of low potential for risk to man .
4.3.2 Other
Given its use pattern (captive intermediate , completely reacted in use) and rapid hydrolysis (halflife 4.4 min. 25 C in non-human study) to normal body metabolite (acetate) , consumer or widespread environmental exposure are not significant scenarios for human exposure to acetic anhydride .
5 CONCLUSIONS AND RECOMMENDATIONS
5.1 Environment
Acetic Anhydride is used solely as an intermediate for chemical synthesis where it is completely reacted . In the hydrosphere, acetic anhydride is rapidly hydrolyzed (half-life 4.4 min .) to acetic acid which is readily biodegradable. In the atmosphere , it is converted to acetic acid which is subject to photooxidative degradation (half-life 22 days) . Toxicity to aquatic organisms is moderate ( 18 to 3400 mg/l) , but it persists only for a short time due to its rapid hydrolysis to acetate/acetic acid . It has virtually no potential for bioaccumulation (log Kow =
-0.27) . The PEC/PNEC ratio was much less than one (1.9 x 10-10) . Therefore , acetic anhydride has a low potential for exposure and is considered to be currently of low priority for further environmental work in the SIDS context .
5.2 Human Health
The critical effect for acetic anhydride is irritancy at the site of contact . Because of its
well-known corrosive and irritating effects on the eyes , skin and respiratory tract and low odor threshold , procedures , equipment (e.g goggles, gloves, respirators) , training and engineering controls have already been in place for many years to prevent exposure . Industrial hygiene monitoring data indicates that levels of acetic anhydride are below 1 ppm 8-hr . (4.2 mg/m3) in facilities where acetic anhydride is produced and where the major use of acetic anhydride takes place . Acetic anhydride is used exclusively as a chemical intermediate and there is no indication that its use is in general practice in the consumer industry . It is suggested that occupational exposure limits be revisited based on the additional testing reported in this SIAR . Acetic anhydride is considered to be currently of low priority for further health-related work in the SIDS context(21) .
Bibliography
1. CEH-Stanford Research Institute International Data Summary 603.5000 A (1996).
2. Gold (1948) : Trans Faraday Soc . 44 , 506-515.
3. Hoechst AG (1975) : (31.07.1975) cited in IUCLID (1996).
4. Placak, Ruchhoft (1947) : Public Health Reports, XVII. The utilization of organic substrates by activated
sludge , Vol . 62, 697 - 716.
5. IUCLID (1996): International Uniform Chemical Information Database.
6. BUA-Stoffbericht No . 70 (1991).
7. Bringmann et al . (1980): Z. Wasser Abwasser Forsch . 13(5), 170-173.
8. Bringmann (1978) : Z . Wasser Abwasser Forsch. 11(6) , 210-215.
9. Bringmann, Kuehn (1981) : Gas-Wasserfach, Wasser-Abwasser 122(7), 308-313.
10. Hoechst AG (1975) : (13.08.1975) Cited in IUCLID (1996).
11. Bringmann, Kuehn (1976) : Gas-Wasserfach , Wasser-Abwasser 117 (9) , 410-413.
12. Bringmann (1975) : Gesund.-Ing. 96(9), 238-241.
13. Bringmann, Kuehn (1980) : Water Res. 14, 231-241.
14. Gloyna, Thirumurthi (1967) : Water Sewage Works 114(3) , 83-88.
15. Bringmann, Kuehn (1982) : Z . Wasser Abwasser Forsch. 15(1) , 1-6.
16. Juhnke, Luedemann (1978) : Z . Wasser Abwasser Forsch. 11(5) , 161-164.
17. Takhirov, M.T. (1969) : Gig Sanit 34(6): 122-125.
18. Acetic Anhydride : 13-week Inhalation Toxicity Study in Rats . Huntingdon Report HST 411/961219
(August 27, 1996).
19. McMahon et al. (1979) : Cancer Res . 39(3), 682-693.
20. Cameron : Short-term test program sponsored by the Division of Cancer Etiology , National Cancer
Institute , Y85 [CCRIS, 1991].
21. Mortelmans et al . (1986) : Environ. Mutagen. 8 (Suppl.7) , 1-119.
论文外文文献翻译3000字左右
南京航空航天大学金城学院 毕业设计（论文）外文文献翻译 系部经济系 专业国际经济与贸易 学生姓名陈雅琼学号2011051115 指导教师邓晶职称副教授 2015年5月
Economic policy,tourism trade and productive diversification （Excerpt） Iza Lejárraga,Peter Walkenhorst The broad lesson that can be inferred from the analysis is that promoting tourism linkages with the productive capabilities of a host country is a multi-faceted approach influenced by a variety of country conditions.Among these,fixed or semi-fixed factors of production,such as land,labor,or capital,seem to have a relatively minor influence.Within the domain of natural endowments,only agricultural capital emerged as significant.This is a result that corresponds to expectations,given that foods and beverages are the primary source of demand in the tourism economy.Hence,investments in agricultural technology may foment linkages with the tourism market.It is also worth mentioning that for significant backward linkages to emerge with local agriculture,a larger scale of tourism may be important. According to the regression results,a strong tourism–agriculture nexus will not necessarily develop at a small scale of tourism demand. It appears that variables related to the entrepreneurial capital of the host economy are of notable explanatory significance.The human development index(HDI), which is used to measure a country's general level of development,is significantly and positively associated with tourism linkages.One plausible explanation for this is that international tourists,who often originate in high-income countries,may feel more comfortable and thus be inclined to consume more in a host country that has a life-style to which they can relate easily.Moreover,it is important to remember that the HDI also captures the relative achievements of countries in the level of health and education of the population.Therefore,a higher HDI reflects a healthier and more educated workforce,and thus,the quality of local entrepreneurship.Related to this point,it is important to underscore that the level of participation of women in the host economy also has a significantly positive effect on linkages.In sum, enhancing local entrepreneurial capital may expand the linkages between tourism and other sectors of the host country.
土木工程外文文献及翻译
本科毕业设计 外文文献及译文 文献、资料题目：Designing Against Fire Of Building 文献、资料来源：国道数据库 文献、资料发表（出版）日期：2008.3.25 院（部）：土木工程学院 专业：土木工程 班级：土木辅修091 姓名：武建伟 学号：2008121008 指导教师：周学军、李相云 翻译日期： 20012.6.1
外文文献: Designing Against Fire Of Buliding John Lynch ABSTRACT: This paper considers the design of buildings for fire safety. It is found that fire and the associ- ated effects on buildings is significantly different to other forms of loading such as gravity live loads, wind and earthquakes and their respective effects on the building structure. Fire events are derived from the human activities within buildings or from the malfunction of mechanical and electrical equipment provided within buildings to achieve a serviceable environment. It is therefore possible to directly influence the rate of fire starts within buildings by changing human behaviour, improved maintenance and improved design of mechanical and electrical systems. Furthermore, should a fire develops, it is possible to directly influence the resulting fire severity by the incorporation of fire safety systems such as sprinklers and to provide measures within the building to enable safer egress from the building. The ability to influence the rate of fire starts and the resulting fire severity is unique to the consideration of fire within buildings since other loads such as wind and earthquakes are directly a function of nature. The possible approaches for designing a building for fire safety are presented using an example of a multi-storey building constructed over a railway line. The design of both the transfer structure supporting the building over the railway and the levels above the transfer structure are considered in the context of current regulatory requirements. The principles and assumptions associ- ated with various approaches are discussed. 1 INTRODUCTION Other papers presented in this series consider the design of buildings for gravity loads, wind and earthquakes.The design of buildings against such load effects is to a large extent covered by engineering based standards referenced by the building regulations. This is not the case, to nearly the same extent, in the
毕业论文外文翻译模板
农村社会养老保险的现状、问题与对策研究社会保障对国家安定和经济发展具有重要作用，“城乡二元经济”现象日益凸现，农村社会保障问题客观上成为社会保障体系中极为重要的部分。建立和完善农村社会保障制度关系到农村乃至整个社会的经济发展，并且对我国和谐社会的构建至关重要。我国农村社会保障制度尚不完善，因此有必要加强对农村独立社会保障制度的构建，尤其对农村养老制度的改革，建立健全我国社会保障体系。从户籍制度上看，我国居民养老问题可分为城市居民养老和农村居民养老两部分。对于城市居民我国政府已有比较充足的政策与资金投人，使他们在物质和精神方面都能得到较好地照顾，基本实现了社会化养老。而农村居民的养老问题却日益突出，成为摆在我国政府面前的一个紧迫而又棘手的问题。 一、我国农村社会养老保险的现状 关于农村养老，许多地区还没有建立农村社会养老体系，已建立的地区也存在很多缺陷，运行中出现了很多问题，所以完善农村社会养老保险体系的必要性与紧迫性日益体现出来。 （一）人口老龄化加快 随着城市化步伐的加快和农村劳动力的输出，越来越多的农村青壮年人口进入城市，年龄结构出现“两头大，中间小”的局面。中国农村进入老龄社会的步伐日渐加快。第五次人口普查显示：中国65岁以上的人中农村为5938万，占老龄总人口的67.4%.在这种严峻的现实面前，农村社会养老保险的徘徊显得极其不协调。 （二）农村社会养老保险覆盖面太小 中国拥有世界上数量最多的老年人口，且大多在农村。据统计，未纳入社会保障的农村人口还很多，截止2000年底，全国7400多万农村居民参加了保险，占全部农村居民的11.18%，占成年农村居民的11.59%.另外，据国家统计局统计，我国进城务工者已从改革开放之初的不到200万人增加到2003年的1.14亿人。而基本方案中没有体现出对留在农村的农民和进城务工的农民给予区别对待。进城务工的农民既没被纳入到农村养老保险体系中，也没被纳入到城市养老保险体系中，处于法律保护的空白地带。所以很有必要考虑这个特殊群体的养老保险问题。
毕业论文英文参考文献与译文
Inventory management Inventory Control On the so-called "inventory control", many people will interpret it as a "storage management", which is actually a big distortion. The traditional narrow view, mainly for warehouse inventory control of materials for inventory, data processing, storage, distribution, etc., through the implementation of anti-corrosion, temperature and humidity control means, to make the custody of the physical inventory to maintain optimum purposes. This is just a form of inventory control, or can be defined as the physical inventory control. How, then, from a broad perspective to understand inventory control? Inventory control should be related to the company's financial and operational objectives, in particular operating cash flow by optimizing the entire demand and supply chain management processes (DSCM), a reasonable set of ERP control strategy, and supported by appropriate information processing tools, tools to achieved in ensuring the timely delivery of the premise, as far as possible to reduce inventory levels, reducing inventory and obsolescence, the risk of devaluation. In this sense, the physical inventory control to achieve financial goals is just a means to control the entire inventory or just a necessary part; from the perspective of organizational functions, physical inventory control, warehouse management is mainly the responsibility of The broad inventory control is the demand and supply chain management, and the whole company's responsibility. Why until now many people's understanding of inventory control, limited physical inventory control? The following two reasons can not be ignored: First, our enterprises do not attach importance to inventory control. Especially those who benefit relatively good business, as long as there is money on the few people to consider the problem of inventory turnover. Inventory control is simply interpreted as warehouse management, unless the time to spend money, it may have been to see the inventory problem, and see the results are often very simple procurement to buy more, or did not do warehouse departments . Second, ERP misleading. Invoicing software is simple audacity to call it ERP, companies on their so-called ERP can reduce the number of inventory, inventory control, seems to rely on their small software can get. Even as SAP, BAAN ERP world, the field of
毕业论文外文翻译模版
吉林化工学院理学院 毕业论文外文翻译English Title（Times New Roman ，三号） 学生学号：08810219 学生姓名：袁庚文 专业班级：信息与计算科学0802 指导教师：赵瑛 职称副教授 起止日期：2012.2.27～2012.3.14 吉林化工学院 Jilin Institute of Chemical Technology
1 外文翻译的基本内容 应选择与本课题密切相关的外文文献（学术期刊网上的），译成中文，与原文装订在一起并独立成册。在毕业答辩前，同论文一起上交。译文字数不应少于3000个汉字。 2 书写规范 2.1 外文翻译的正文格式 正文版心设置为：上边距：3.5厘米，下边距：2.5厘米，左边距：3.5厘米，右边距：2厘米，页眉：2.5厘米，页脚：2厘米。 中文部分正文选用模板中的样式所定义的“正文”，每段落首行缩进2字；或者手动设置成每段落首行缩进2字，字体：宋体，字号：小四，行距：多倍行距1.3，间距：前段、后段均为0行。 这部分工作模板中已经自动设置为缺省值。 2.2标题格式 特别注意：各级标题的具体形式可参照外文原文确定。 1．第一级标题（如：第1章绪论）选用模板中的样式所定义的“标题1”，居左；或者手动设置成字体：黑体，居左，字号：三号，1.5倍行距，段后11磅，段前为11磅。 2．第二级标题（如：1.2 摘要与关键词）选用模板中的样式所定义的“标题2”，居左；或者手动设置成字体：黑体，居左，字号：四号，1.5倍行距，段后为0，段前0.5行。 3．第三级标题（如：1.2.1 摘要）选用模板中的样式所定义的“标题3”，居左；或者手动设置成字体：黑体，居左，字号：小四，1.5倍行距，段后为0，段前0.5行。 标题和后面文字之间空一格（半角）。 3 图表及公式等的格式说明 图表、公式、参考文献等的格式详见《吉林化工学院本科学生毕业设计说明书（论文）撰写规范及标准模版》中相关的说明。
java毕业论文外文文献翻译
Advantages of Managed Code Microsoft intermediate language shares with Java byte code the idea that it is a low-level language witha simple syntax , which can be very quickly translated intonative machine code. Having this well-defined universal syntax for code has significant advantages. Platform independence First, it means that the same file containing byte code instructions can be placed on any platform; atruntime the final stage of compilation can then be easily accomplished so that the code will run on thatparticular platform. In other words, by compiling to IL we obtain platform independence for .NET, inmuch the same way as compiling to Java byte code gives Java platform independence. Performance improvement IL is actually a bit more ambitious than Java bytecode. IL is always Just-In-Time compiled (known as JIT), whereas Java byte code was ofteninterpreted. One of the disadvantages of Java was that, on execution, the process of translating from Javabyte code to native executable resulted in a loss of performance. Instead of compiling the entire application in one go (which could lead to a slow start-up time), the JITcompiler simply compiles each portion of code as it is called (just-in-time). When code has been compiled.once, the resultant native executable is stored until the application exits, so that it does not need to berecompiled the next time that portion of code is run. Microsoft argues that this process is more efficientthan compiling the entire application code at the start, because of the likelihood that large portions of anyapplication code will not actually be executed in any given run. Using the JIT compiler, such code willnever be compiled.
土木工程外文文献翻译
专业资料 学院： 专业：土木工程 姓名： 学号： 外文出处：Structural Systems to resist (用外文写) Lateral loads 附件：1.外文资料翻译译文；2.外文原文。
附件1：外文资料翻译译文 抗侧向荷载的结构体系 常用的结构体系 若已测出荷载量达数千万磅重，那么在高层建筑设计中就没有多少可以进行极其复杂的构思余地了。确实，较好的高层建筑普遍具有构思简单、表现明晰的特点。 这并不是说没有进行宏观构思的余地。实际上，正是因为有了这种宏观的构思，新奇的高层建筑体系才得以发展，可能更重要的是：几年以前才出现的一些新概念在今天的技术中已经变得平常了。 如果忽略一些与建筑材料密切相关的概念不谈，高层建筑里最为常用的结构体系便可分为如下几类： 1.抗弯矩框架。 2.支撑框架，包括偏心支撑框架。 3.剪力墙，包括钢板剪力墙。 4.筒中框架。 5.筒中筒结构。 6.核心交互结构。 7. 框格体系或束筒体系。 特别是由于最近趋向于更复杂的建筑形式，同时也需要增加刚度以抵抗几力和地震力，大多数高层建筑都具有由框架、支撑构架、剪力墙和相关体系相结合而构成的体系。而且，就较高的建筑物而言，大多数都是由交互式构件组成三维陈列。 将这些构件结合起来的方法正是高层建筑设计方法的本质。其结合方式需要在考虑环境、功能和费用后再发展，以便提供促使建筑发展达到新高度的有效结构。这并
不是说富于想象力的结构设计就能够创造出伟大建筑。正相反，有许多例优美的建筑仅得到结构工程师适当的支持就被创造出来了，然而，如果没有天赋甚厚的建筑师的创造力的指导，那么，得以发展的就只能是好的结构，并非是伟大的建筑。无论如何，要想创造出高层建筑真正非凡的设计，两者都需要最好的。 虽然在文献中通常可以见到有关这七种体系的全面性讨论，但是在这里还值得进一步讨论。设计方法的本质贯穿于整个讨论。设计方法的本质贯穿于整个讨论中。 抗弯矩框架 抗弯矩框架也许是低，中高度的建筑中常用的体系，它具有线性水平构件和垂直构件在接头处基本刚接之特点。这种框架用作独立的体系，或者和其他体系结合起来使用，以便提供所需要水平荷载抵抗力。对于较高的高层建筑，可能会发现该本系不宜作为独立体系，这是因为在侧向力的作用下难以调动足够的刚度。 我们可以利用STRESS，STRUDL 或者其他大量合适的计算机程序进行结构分析。所谓的门架法分析或悬臂法分析在当今的技术中无一席之地，由于柱梁节点固有柔性，并且由于初步设计应该力求突出体系的弱点，所以在初析中使用框架的中心距尺寸设计是司空惯的。当然，在设计的后期阶段，实际地评价结点的变形很有必要。 支撑框架 支撑框架实际上刚度比抗弯矩框架强，在高层建筑中也得到更广泛的应用。这种体系以其结点处铰接或则接的线性水平构件、垂直构件和斜撑构件而具特色，它通常与其他体系共同用于较高的建筑，并且作为一种独立的体系用在低、中高度的建筑中。
毕业论文(英文翻译)排版格式
英文翻译说明 1. 英文翻译文章输成word，5号新罗马（New Times Roman）字体，1.5倍行间距，将来方便打印和一起装订；英文中的图表要重新画，禁止截图。 2. 整篇论文1.5倍行间距，打印时，用B5纸，版面上空2.5cm，下空2cm，左空2.5cm，右空2cm（左装订）。 3. 论文翻译后的摘要用五号宋体，正文小四号宋体、英文和数字用新罗马（New Times Roman）12、参考文献的内容用五号字体。图和表头用五号字体加粗并居中，图和表中的内容用五号字体。论文翻译的作者用五号字体加粗。 论文大标题………小三号黑体、加黑、居中 第二层次的题序和标题………小四号黑体、加黑、居中 第三层次的题序和标题………小四号宋体、加黑、居中 正文……………………………小四号宋体、英文用新罗马12 页码……………………………小五号居中，页码两边不加修饰符 4. 论文中参考文献严格按照下述排版。 专著格式：序号.编著者.书名[M].出版地: 出版社, 年代, 起止页码 期刊论文格式：序号.作者.论文名称[J]. 期刊名称, 年度, 卷(期): 起止页码 学位论文格式：序号.作者.学位论文名称[D]. 发表地: 学位授予单位, 年度 例子: (1).胡千庭, 邹银辉, 文光才等. 瓦斯含量法预测突出危险新技术[J]. 煤炭学报, 2007.32(3): 276-280. (2). 胡千庭. 煤与瓦斯突出的力学作用机理及应用研究[D]. 北京: 中国矿业大学(北京), 2007. (3). 程伟. 煤与瓦斯突出危险性预测及防治技术[M]. 徐州: 中国矿业大学出版社, 2003.
大学毕业论文---软件专业外文文献中英文翻译
软件专业毕业论文外文文献中英文翻译 Object landscapes and lifetimes Tech nically, OOP is just about abstract data typing, in herita nee, and polymorphism, but other issues can be at least as importa nt. The rema in der of this sect ion will cover these issues. One of the most importa nt factors is the way objects are created and destroyed. Where is the data for an object and how is the lifetime of the object con trolled? There are differe nt philosophies at work here. C++ takes the approach that con trol of efficie ncy is the most importa nt issue, so it gives the programmer a choice. For maximum run-time speed, the storage and lifetime can be determined while the program is being written, by placing the objects on the stack (these are sometimes called automatic or scoped variables) or in the static storage area. This places a priority on the speed of storage allocatio n and release, and con trol of these can be very valuable in some situati ons. However, you sacrifice flexibility because you must know the exact qua ntity, lifetime, and type of objects while you're writing the program. If you are trying to solve a more general problem such as computer-aided desig n, warehouse man ageme nt, or air-traffic con trol, this is too restrictive. The sec ond approach is to create objects dyn amically in a pool of memory called the heap. In this approach, you don't know un til run-time how many objects you n eed, what their lifetime is, or what their exact type is. Those are determined at the spur of the moment while the program is runnin g. If you n eed a new object, you simply make it on the heap at the point that you n eed it. Because the storage is man aged dyn amically, at run-time, the amount of time required to allocate storage on the heap is sig ni fica ntly Ion ger tha n the time to create storage on the stack. (Creat ing storage on the stack is ofte n a si ngle assembly in structio n to move the stack poin ter dow n, and ano ther to move it back up.) The dyn amic approach makes the gen erally logical assumpti on that objects tend to be complicated, so the extra overhead of finding storage and releas ing that storage will not have an importa nt impact on the creati on of an object .In additi on, the greater flexibility is esse ntial to solve the gen eral program ming problem. Java uses the sec ond approach, exclusive". Every time you want to create an object, you use the new keyword to build a dyn amic in sta nee of that object. There's ano ther issue, however, and that's the lifetime of an object. With Ian guages that allow objects to be created on the stack, the compiler determines how long the object lasts and can automatically destroy it. However, if you create it on the heap the compiler has no kno wledge of its lifetime. In a Ianguage like C++, you must determine programmatically when to destroy the
毕业论文5000字英文文献翻译
英文翻译 英语原文： . Introducing Classes The only remaining feature we need to understand before solving our bookstore problem is how to write a data structure to represent our transaction data. In C++ we define our own data structure by defining a class. The class mechanism is one of the most important features in C++. In fact, a primary focus of the design of C++ is to make it possible to define class types that behave as naturally as the built-in types themselves. The library types that we've seen already, such as istream and ostream, are all defined as classesthat is,they are not strictly speaking part of the language. Complete understanding of the class mechanism requires mastering a lot of information. Fortunately, it is possible to use a class that someone else has written without knowing how to define a class ourselves. In this section, we'll describe a simple class that we canuse in solving our bookstore problem. We'll implement this class in the subsequent chapters as we learn more about types,expressions, statements, and functionsall of which are used in defining classes. To use a class we need to know three things: What is its name? Where is it defined? What operations does it support? For our bookstore problem, we'll assume that the class is named Sales_item and that it is defined in a header named Sales_item.h. The Sales_item Class The purpose of the Sales_item class is to store an ISBN and keep track of the number of copies sold, the revenue, and average sales price for that book. How these data are stored or computed is not our concern. To use a class, we need not know anything about how it is implemented. Instead, what we need to know is what operations the class provides. As we've seen, when we use library facilities such as IO, we must include the associated headers. Similarly, for our own classes, we must make the definitions associated with the class available to the compiler. We do so in much the same way. Typically, we put the class definition into a file. Any program that wants to use our class must include that file. Conventionally, class types are stored in a file with a name that, like the name of a program source file, has two parts: a file name and a file suffix. Usually the file name is the same as the class defined in the header. The suffix usually is .h, but some programmers use .H, .hpp, or .hxx. Compilers usually aren't picky about header file names, but IDEs sometimes are. We'll assume that our class is defined in a file named Sales_item.h. Operations on Sales_item Objects
土木工程类专业英文文献及翻译
PA VEMENT PROBLEMS CAUSED BY COLLAPSIBLE SUBGRADES By Sandra L. Houston,1 Associate Member, ASCE (Reviewed by the Highway Division) ABSTRACT: Problem subgrade materials consisting of collapsible soils are com- mon in arid environments, which have climatic conditions and depositional and weathering processes favorable to their formation. Included herein is a discussion of predictive techniques that use commonly available laboratory equipment and testing methods for obtaining reliable estimates of the volume change for these problem soils. A method for predicting relevant stresses and corresponding collapse strains for typical pavement subgrades is presented. Relatively simple methods of evaluating potential volume change, based on results of familiar laboratory tests, are used. INTRODUCTION When a soil is given free access to water, it may decrease in volume, increase in volume, or do nothing. A soil that increases in volume is called a swelling or expansive soil, and a soil that decreases in volume is called a collapsible soil. The amount of volume change that occurs depends on the soil type and structure, the initial soil density, the imposed stress state, and the degree and extent of wetting. Subgrade materials comprised of soils that change volume upon wetting have caused distress to highways since the be- ginning of the professional practice and have cost many millions of dollars in roadway repairs. The prediction of the volume changes that may occur in the field is the first step in making an economic decision for dealing with these problem subgrade materials. Each project will have different design considerations, economic con- straints, and risk factors that will have to be taken into account. However, with a reliable method for making volume change predictions, the best design relative to the subgrade soils becomes a matter of economic comparison, and a much more rational design approach may be made. For example, typical techniques for dealing with expansive clays include: (1) In situ treatments with substances such as lime, cement, or fly-ash; (2) seepage barriers and/ or drainage systems; or (3) a computing of the serviceability loss and a mod- ification of the design to "accept" the anticipated expansion. In order to make the most economical decision, the amount of volume change (especially non- uniform volume change) must be accurately estimated, and the degree of road roughness evaluated from these data. Similarly, alternative design techniques are available for any roadway problem. The emphasis here will be placed on presenting economical and simple methods for: (1) Determining whether the subgrade materials are collapsible; and (2) estimating the amount of volume change that is likely to occur in the 'Asst. Prof., Ctr. for Advanced Res. in Transp., Arizona State Univ., Tempe, AZ 85287. Note. Discussion open until April 1, 1989. To extend the closing date one month,