Stable Organic Titanium Catalysts and Reactive Distillation Used for the Transesterification of Dimethyl Carbonate with Phenol

The transesterification of dimethyl carbonate with phenol to methyl phenyl carbonate (MPC) was investigated on novel catalysts such as titanium diisopropoxide bis(ethyl acetoacetate) and titanium dibutoxide bis(ethyl acetoacetate) in a closed batch reactor at 185–206 °C under high pressure. The produced methanol could be removed efficiently by reactive distillation in order to overcome the equilibrium. The prepared catalysts have higher resistance to water than titanium alkoxides. Phenol conversion as high as 86.4 % with an MPC selectivity of 99.4 % was achieved under optimal reaction conditions within 9 h. Most of the catalytic activity was retained after repeated use for ten times.     

荧光试剂N-[对-(2-苯并噁唑基)-苯基]-马来酰亚胺测定半胱氨酸、谷胱甘肽的研究

介绍了一种新的测定半胱氨酸和还原型谷胱甘肽的荧光光度法.N-[对-(2-苯并噁唑基)-苯基]-马来酰亚胺是一种有很弱荧光的活性试剂,可以和硫醇定量反应,其加成产物有强烈荧光.利用加成产物的荧光,可以测定半胱氨酸和还原型谷胱甘肽,检出限量分别是4.0×10-10mol@L-1和3.2×10-10mol@L-1(SNR=3).该方法可以用于蛋白质和胱氨酸水解液中半胱氨酸的测定.     

1-苯基-3-甲基-5-吡唑啉酮的合成工艺研究

在无水乙醇的存在下，乙酰乙酸乙酯和苯肼为原料合成标题化合物、采用单因素实验法，得到最佳配比为乙酰乙酸乙酯：苯肼=1.05(摩尔比)，无水乙醇50m，反应温度70℃，反应2小时，再回流7小时，收率90．9％，产品纯度99.0％以上。     

Facile synthesis and characterization of star‐shaped polystyrene: self‐condensing atom transfer radical copolymerization of N‐[4‐(α‐bromoisobutyryloxy)phenyl]maleimide and styrene

BACKGROUND: Generation of stars around in situ formed cores provides a facile approach to star‐shaped polymers. Therefore the self‐condensing atom transfer radical copolymerization (SCATRCP) of N‐[4‐(α‐bromoisobutyryloxy)phenyl]maleimide (BiBPM) and a large excess of styrene (St) was investigated. RESULTS: BiBPM and St formed a charge transfer complex (CTC), which underwent the SCATRCP, leading to the branched core initiating the atom transfer radical polymerization of St, finally giving star‐shaped polystyrene (PS). Kinetic and structural study showed that a higher dosage of BiBPM resulted in an enhanced polymerization rate, a higher degree of branching and a larger number of short PS arms. Differential scanning calorimetry suggested that the glass transition temperature of the star‐shaped PS decreased with molecular weight. Melt rheometry showed that even a slightly branched architecture of the PS led to a significantly lower viscosity; both the melt flow index and the activation energy increased with the degree of branching. CONCLUSION: Due to the preferential consumption of BiBPM and formation of a CTC, even a very low dosage of BiBPM could lead to star‐shaped PS, which, in comparison with linear analogues, could possess much better melt fluidity. Copyright © 2008 Society of Chemical Industry     

对苯乙炔苯丙二酮类稀土配体的理论研究

采用RHF法就对苯乙炔苯丙二酮类稀土配体进行了理论计算,得到了它们的结构、基态能量、原子电荷、原子间距、轨道能级等。结果表明,1-环戊二烯-3-(p-对苯乙炔苯基)-1,3-丙二酮和1-噻吩基-3-(p-对苯乙炔苯基)-1,3-丙二酮可与稀土离子形成更为稳定的发光配位化合物。     

Conditioning of stimuli with nonzero initial value.

In five experiments, rats received conditioning of either moderately attractive or moderately aversive flavors using either a strongly negative lithium chloride (LiCl) or a strongly positive Polycose as the reinforcer. In each case, testing was done with a compound of the two moderately valued stimuli to determine the amount of associative change produced by the pairing. In both within-subject and between-subjects designs, the amount of associative change was greater for a signal whose moderate value was opposite in valence from that of the reinforcer. This suggests that, like learned stimulus value, inherent stimulus value can modulate further associative learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

抗氧剂三(壬苯基)亚磷酸酯生产工艺改进

介绍了三（壬苯基）亚磷酸酯生产工艺的改进，并对各种工艺因素的影响进行研究，找出最佳工艺条件。     

双酚S型聚酰亚胺二胺单体的合成与表征

以对氯硝基苯和双酚S为原料经缩合和铁粉还原合成了聚酰亚胺二胺单体4,4’-双(4-氨基苯氧基)二苯基砜(P-BAPS);考查了工艺条件对产物收率的影响,并利用红外光谱(IR)、差式扫描量热仪(DSC)对其及聚合物进行表征.结果表明:当n(硝基物)∶n(铁粉)=1∶6.75,80℃下反应6h,产物收率可达87.70％;相...     

大米肽中压离子交换色谱分离及其免疫活性评价

为了建立一种以高效液相色谱检测大米肽中氨基酸含量的方法,以异硫氰酸苯酯（Phenyl isothiocyanate,PITC）为柱前衍生剂,实现大米肽中16种氨基酸（天冬氨酸（Asp）、谷氨酸（Glu）、丝氨酸（Ser）、甘氨酸（Gly）、组氨酸（His）、精氨酸（Arg）、苏氨酸（Thr）、丙氨酸（Ala）、脯氨酸（Pro）、酪氨酸（Tyr）、缬氨酸（Val）、蛋氨酸（Met）、异亮氨酸（Ile）、亮氨酸（Leu）、苯丙氨酸（Phe）、赖氨酸（Lys））能同时、快速、有效地分析检测。采用Athena AAA色谱柱为分析柱,以甲醇:乙腈:水=20:60:20和50 mmol/L乙酸钠（pH6.5）为流动相,进行梯度洗脱,流速为1.0 mL/min,柱温35 ℃,紫外检测器波长为254 nm。结果表明,16种氨基酸在0.125~2.5 μmol/mL范围内具有良好的线性关系,14种氨基酸线性关系的决定系数R²≥0.9999,另外2种氨基酸的决定系数R²分别为0.9998和0.9994,检出限为0.003%~0.018%,定量限为0.010%~0.059%,加标回收率在82.21%~103.59%,RSD均小于5%。该方法使得大米肽中16种氨基酸很好地分离,其中含量最高的氨基酸是谷氨酸（Glu）,含量范围为13.11%±0.39%~21.38%±0.48%,含量最低的氨基酸是组氨酸（His）或蛋氨酸（Met）,含量范围为1.59%±0.05%~2.27%±0.03%或1.26%±0.05%~2.32%±0.06%,其准确度和精密度佳,灵敏度和回收率高,适用于大米肽的氨基酸含量分析。

     

Analysis of Volatile Bread Aroma for Evaluation of Bread Freshness Using an Electronic Nose (E-Nose)

This paper presents the use of a tin-oxide sensor array and self-organized map (SOM)-based E-nose for analysis of volatile bread aroma and explores its ability to cluster bread odor data according to the freshness of bread. A low cost tin-oxide sensor array based electronic nose system has been used for the classification of state of freshness of bread. The sensor data was acquired for a period of 3 weeks, and an unsupervised self-organizing map (SOM) model was trained using this data to correlate the sensor response to classify the bread as fresh and stale. A comparative evaluation of 3 week' of bread data was carried out using the SOM. The results suggest that the system developed is able to predict the state of bread as fresh and stale up to 98% accuracy if the test bread data sets are of the same week. The classification accuracy reduces to 75-85% if test bread data sets are from different weeks. The model is also applied on three different brands of bread and similar classification results are obtained.