精馏一结晶联合分离法分离挥发度相近物系

研究了精馏－结晶联合法的分离工艺，介绍了精馏－结晶联合分离法的传质机理，数学模型，操作线方程，用对二氯苯－邻二氯苯物质，对精馏－结晶联合分离法与纯精馏方法进行了对比，结果表明，前者设备投资比后者节省60％，能耗节省57％，冷却水消耗减少57％，表明它是一种很有开发前景的工业分离方法。     

用精馏-降膜结晶耦合技术提纯对二氯苯

用精馏-降膜结晶耦合工艺分离对二氯苯。考察了降膜结晶操作中冷却剂温度、发汗升温速率对产品的影响,结果表明,冷却剂的温度为38℃,发汗速率为0. 5℃/min,可使w(对二氯苯)≥99 7%,单程收率>58%。与使用精馏工艺相比,总能耗下降71 7%。     

结晶精馏耦合流程分离MDI同分异构体的新工艺

提出了一套关于结晶精馏耦合分离MDI同分异构体的工艺流程,该新工艺采用先结晶后精馏,精馏产物再返回结晶器的方法.分别对结晶和精馏流程进行了模拟分析,并从能耗角度对新工艺与原有工艺进行比较.结果表明,该结晶精馏耦合分离MDI同分异构体工艺所得结晶产品中4,4′-MDI纯度达到99%以上时,其能耗仅是真空精馏工艺能耗的1/2～2/7.新工艺工业化后将产生良好的经济效益.     

煤焦油中蒽、菲、咔唑的精制技术

主要介绍了煤焦油中蒽、菲和咔唑的精制方法,系统地总结了溶剂洗涤法、精馏-溶剂法、结晶-精馏法、乳化液膜法、区域熔融法、溶剂萃取-恒沸蒸馏-升华法和化学分离法、新型分离法等精制蒽、菲及咔唑的工艺原理,对各种方法所具有的优势及不足之处进行了评述。     

十二烷二酸二甲酯粗品的精馏-结晶纯化

采用精馏-结晶法分离以环己酮为原料合成十二烷二酸二甲酯的粗品,探讨了各种工艺条件对结晶分离的影响.结果表明:结晶分离最佳工艺条件为:m(精馏双酯)∶m(甲醇)=1∶0.8～1.5,结晶溶液始温30℃左右,终温5～8 ℃,降温速率2～3 ℃/min,搅拌速度5～25 r/min;结晶母液中甲醇可通过蒸馏回收循环使用,残留双酯返回精馏系统.所得十二烷二酸二甲酯的纯度可达99.5%以上,符合医药中间体、香料等行业的使用要求.     

萃取法分离乙腈、乙酸乙酯和水混合物的研究

为了从制药废料中回收乙腈和乙酸乙酯,研究了反萃取精馏分离法在分离乙腈-乙酸乙酯中的应用,确定了首先进行预处理,然后进行萃取精馏的工艺过程及工艺条件。采用以上技术从废液中回收乙酸乙酯,乙酸乙酯含量达到98.5%以上。     

新型精馏集成技术用于混合硝基氯化苯分离的研究

介绍了硝基氯苯3种同分异构体的性质、用途及生产现状,分析了混合硝基氯苯分离的难点,对目前已有的分离方法进行了综述,指出了各种分离方法的优点和不足。提出了侧线精馏-萃取精馏-结晶相结合的新型精馏集成技术用于混合硝基氯苯的分离,与传统工艺相比,该过程工艺简单,分离效率高,分离的能耗大大降低。     

3,5-二甲酚的研制

介绍了对化工新产品3,5-二甲酚的研制、开发。以焦油中低附加值产品工业二甲酚后馏分为原料,用精馏的方法可以得到质量分数>95%的3,5-二甲酚高附加值产品。试验表明,通过一次精馏生产质量分数>95%的产品,在精馏分离3,5-二甲酚的同时,经结晶、抽滤还可得到质量分数>95%的3,4-二甲酚产品。     

变压精馏和萃取精馏分离四氢呋喃-水模拟及节能

基于四氢呋喃/水共沸体系的特性,研究了变压精馏和萃取精馏2种工艺分离四氢呋喃和水的方法,进一步考察了2种工艺的可行性及节能情况。物性计算方法采用NRTL活度系数方程,其二元相互作用参数通过汽液相平衡实验数据回归获得,采用Aspen Plus对上述2种工艺进行模拟及优化,获得了2种工艺较优的工艺参数,并对比能耗。结果表明:采用双塔热集成变压精馏工艺或双塔萃取精馏工艺均可有效地分离四氢呋喃-水二元共沸体系,四氢呋喃产品符合《GB/T 24772—2009工业用四氢呋喃》优等品规格,但热集成变压精馏工艺更为节能,节省循环水11. 0%、节省蒸汽20. 3%,且不引入第三组分,更适合四氢呋喃-水体系的分离,为该共沸体系分离的设计与节能提供依据。     

基于机械蒸汽再压缩和有机朗肯循环技术的双溶剂协同萃取精馏分离乙酸甲酯-甲醇-水节能工艺

针对双溶剂协同萃取精馏分离乙酸甲酯-甲醇-水三塔分离工艺特性及高能耗特点,把机械蒸汽再压缩(MVR)和有机朗肯循环(ORC)余热发电技术应用于该三塔的优化,提出了带中间再沸器的MVR热泵和ORC耦合MVR热泵两种节能精馏工艺。以年总费用(TAC)为精馏工艺评价指标,净输出功为ORC系统评价指标,采用Aspen Plus软件对提出的节能工艺进行模拟与优化。研究结果表明,就乙酸甲酯回收塔和甲醇回收塔而言,带中间再沸器的MVR热泵精馏工艺较常规双溶剂协同萃取精馏工艺能耗分别减少了57.38%和9.66%;TAC分别节省了31.34%和11.69%。而对于溶剂回收塔,带中间预分塔的ORC耦合MVR热泵精馏工艺较常规双溶剂协同萃取精馏工艺能耗减少了50.16%,TAC节省了36.13%。就整个萃取精馏系统而言,优化后的精馏工艺比原有双溶剂协同萃取精馏工艺能耗减少了45.48%,TAC节省了31.33%。     

魔芋葡甘露聚糖提纯及性能研究

分析了近年来各种魔芋葡甘露聚糖 (KGM )的分离纯化方法 ,讨论了它们的优缺点。通过实验 ,得出了一种简单、易操作的精制KGM的方法 ,产率为 5 7% ,产品无色、无味 ,其溶胶保存84h仍均一、透明、无异味 ,显示产品有较高质量分数。傅立叶红外光谱进一步证实上述结论。热性能测试显示该法制得的魔芋葡甘露聚糖有很好的热稳定性 ,其分解温度为 2 90℃。     

Synthesis and characterization of a stable analog of the phosphorylated form of the chemotaxis protein CheY

The bacterial chemotaxis protein CheY is activated in vivo by the covalent phosphorylation of a single aspartate residue at position 57. However, this phosphate linkage is unstable (t1/2 approximately 20 s at room temperature), thereby precluding many biochemical analyses. Here we present a synthetic scheme to prepare an analog of CheY-phosphate (Che Y-P) with chemical stability of the phosphate linkage enhanced by several orders of magnitude relative to the native protein. Starting with CheY D57C, a site-specific mutant of CheY with a unique cysteine residue in place of the aspartate at position 57, two sequential disulfide exchange reactions were performed to form the final product 'CheY D57C-SPO3' with a thiophosphate moiety covalently bonded to the protein in a disulfide linkage. Mass spectral analysis showed that the desired analog was present at 70-80% of the total protein. The disulfide linkage had a t1/2 of 8 days at 4 degrees C. Biochemical characterization of CheY D57C-SPO3 included assessment of conformational properties using tryptophan fluorescence, evaluation of metal binding properties and measurement of binding interactions with the chemotaxis proteins CheZ and FliM. Despite possessing a phosphoryl group at a nearly identical location as native CheY-phosphate, the analog was unable to emulate CheY-phosphate function, thereby supporting the idea that there are very precise geometric requirements for successful CheY activation.      

Variablity of the intestinal uptake of lipids is genetically determined in mice

The response of the plasma cholesterol concentration to changes in dietary lipids varies widely in humans and animals. There are variations in the in vivo absorption of cholesterol between different strains of mice. This study was undertaken in three strains of inbred mice to test the hypotheses that: (i) there are strain differences in the in vitro uptake of fatty acids and cholesterol and (ii) the adaptability of the intestine to respond to variations in dietary lipids is genetically determined. An in vitro intestinal ring technique was used to assess the uptake of medium- and long-chain fatty acids and cholesterol into jejunum and ileum of adult DBA/2, C57BL6, and C57L/J mice. The jejunal uptake of cholesterol was similar in C57L/J, DBA/2, or C57BL6 fed ad libitum a low-fat (5.7% fat, no cholesterol) chow diet. This is in contrast to a previous demonstration that in vivo cholesterol absorption was lower in C57L/J than in the other murine strains. The jejunal uptake of several long-chain fatty acids was greater in DBA/2 fed for 4 wk the high-fat (15.8% fat and 1.25% cholesterol) as compared with the low-fat diet. Furthermore, on the high-fat diet, the uptake of many long-chain fatty acids was higher in DBA/2 than in C57BL6 or C57L/J. The differences in cholesterol and fatty acid uptake were not explained by variations in food uptake, body weight gain, or the weight of the intestine. In summary: (i) there are strain differences in the in vitro intestinal uptake of fatty acids but not of cholesterol; (ii) a high-fat diet enhances the uptake of long-chain fatty acids in only one of the three strains examined in this study; and (iii) the pattern of strain- and diet-associated alterations in the in vivo absorption of cholesterol differs from the pattern of changes observed in vitro. We speculate that genetic differences in cholesterol and fatty acid uptake are explained by variations in the expression of protein-mediated components of lipid uptake.     

异丁酸-3-羟基-2，2，4-三甲基戊酯的制备

本文介绍了利用羰基合成的副产物异丁醛制备化工原料异丁酸－3－羟基－2，2，4－三甲基戊酯的方法。通过对其条件的探索和选择，可获得57．18％的收率。本方法有较好的实用价值。     

地笋中挥发油化学成分的气相色谱-质谱分析

为了分析地笋(Rhezoma Lycopi)挥发油的化学成分,用药典方法提取地笋挥发油,用毛细管气相色谱-质谱(GC-MS)获得其总离子流图,对各个色谱峰进行了定性,并用面积归一化法获得各化合物的相对质量分数,共鉴定了57个化合物,占总挥发油质量的87.12%。酯类为地笋挥发油的主要成分,占总挥发油质量的49.82%,其中邻苯二甲酸二丁酯质量分数最高,为20.19%。该文较系统地分析鉴定了地笋挥发油成分,为其化学成分的研究提供了参数。     

食用菌制全降解包装材料的研究

为了解决不可降解的废弃塑料类包装材料对环境的污染,以秸秆和木屑为主要原料,利用食用菌栽培技术制备了一种新型的、可完全降解的包装材料。采用对比实验的方法,研究了不同原料配比对菌丝生长情况的影响,结果表明,在秸秆57%、木屑30%、麸皮10%、石膏1%、石灰2%的配比下,选用平菇菌种栽培的培养基菌丝体含量最多,紧实度最好。通过材料的防水性能测试和缓冲性能比较,表明该生物质材料完全可以替代EPS(发泡聚苯乙烯)和EPE(发泡聚乙烯)等包装材料。同时,该生物质材料在土壤中可实现完全降解,为土壤提供有机肥料。     

Determination of the oxidative stability of fats and oils: Comparison between the active oxygen method (AOCS Cd 12-57) and the rancimat method

Oxidative stability is an important parameter in the characterization of fats and oils. The determination of this parameter with the Active Oxygen Method (AOM; AOCS Method Cd 12-57) is both very costly and labor intensive, owing to the repeated peroxide value determinations involved. The alternative rancimat method is based on the conductometric determination of volatile degradation products and features automatic plotting of the conductivity against time. The evaluation is performed graphically after completion of the experiment. The labor required for this method is considerably less as it is not necessary to perform titrations at regular intervals. In the determination of the peroxide values of six samples at three temperatures, ca 151 mixed solvent and chemicals valued at SFr. 400 (ca $180 US) were consumed. The induction times (t _I ) determined with both methods using six different fats and oils show a good correlation (slope 1.005, correlation coefficient 0.987). The rancimat method thus yields results equivalent to the AOCS Method Cd 12–57, but offers a real alternative for the determination of oxidative stabilities owing to the appreciable saving in labor.     

Production of porous polylactic acid monoliths via nonsolvent induced phase separation

Polylactic acid (PLA) is one of the most promising polymers for use as the matrix of a bone scaffold. In this work, porous PLA monoliths are fabricated via nonsolvent induced phase separation using dichloromethane as a solvent and hexane as a nonsolvent. The PLA-dichloromethane-hexane compositions which undergo liquid–liquid phase separation followed by gelation are shown to allow for the production of high quality foams. Solvent exchange with methanol after aging the gel is found to substantially reduce shrinkage during drying. Using this simple, versatile and template-free method we produced PLA foams with porosities as high as ∼90.8%, specific surface area up to 54.14 m²/g, crystallinity up to 62.6% and compressive modulus ranging from 1.8 to 57 MPa. Depending on ternary mixture concentration and standing temperature a range of mesoporous and combined meso/macroporous morphologies suitable for use as a bone scaffold are produced.     

Numerical determination of fluid-to-particle mass and heat transfer coefficients in packed bed reactors

A method based on particle-resolved CFD is built and validated, to calculate the fluid-to-particle mass and heat transfer coefficients in packed beds of spheres with different tube-to-particle diameter ratios (N) and of various particle shapes with N = 5.23. This method is characterized by considering axial dispersion. The mass and heat transfer coefficients increase by 5%–57% and 9%–63% after considering axial dispersion, indicating axial dispersion should be included in the method. The mass and heat transfer coefficients are reduced as N decreases. The catalyst particles without inner holes show higher mass and heat transfer coefficients than the ones with inner holes, because of unfavorable fluid flow in inner holes. The bed of trilobes has the highest mass and heat transfer coefficients, being 85% and 95% higher than the one of spheres. This work provides a versatile method and some useful guidance for the design of packed bed reactors.     

A micromethod for the estimation of blood dolichol

A micromethod for the estimation of dolichol in blood was developed using high performance liquid chromatography. This method can be applied to whole blood or plasma. With detector sensitivity set at 0.005 Absorbance Unit Full Scale, samples as little as 50 μl are sufficient to carry out the determination. Blood samples from the tail vein of inbred strains of C57 BL/6 NNia-1 mice 3,6, 12 and 24 mo of age were examined. Blood dolichol levels decreased with age from 163.3 ng/ml at 6 mo to 110.1 ng/ml at 24 mo. The major dolichol homologs were C-85 (10.4%), C-90 (41.6%), C-95 (38.0%) and C-100 (8.1%).