非均相羰基氧化合成碳酸二苯酯反应液组分的分析

通过色质联用仪对非均相催化一步合成碳酸二苯酯(DPC)过程中的反应液的主要产物及副产物进行了定性分析，其结果发现该反应的主要副产物为苯氧基丙酸和4-苯氧基苯酚以及四丁基铵盐；用气相色谱外标法对反应液中的DPC进行了定量分析，并通过回归法得到了定量分析：DPC的计算方程式，实验证明该方程在DPC的浓度小于10％范围内比较可靠。     

Synthesis and Mesogenic Properties of Liquid Crystals Containing Terminal Cyclohexylmethanol,Cyclopentylmethanol, Cyclobutylmethanol and Cyclopropylmethanol Moiety

Four series of compounds 11?50 containing terminal alicyclic rings such as cyclohexylmethyl, cyclopentylmethyl, cyclobutylmethyl, and cyclopropylmethyl rings were synthesized and their liquid crystal behavior studied. The ring size and the length of flexible alkoxy chain influence the phase formation in different ways. While the smaller ring and the shorter alkoxy chain tend to favor the formation of the N phase, the larger ring and the longer alkoxy chain tend to favor the formation of the SmC phase. All the compounds except 11 and 21 exhibit SmA phases. The widest temperature range of the N, SmA, and SmC phases are found in the compounds 41 , 46 , and 20 , respectively, which are 75 °C for 41 , 115 °C for 46 , and 100 °C for 20 .     

带功能基的全氟烷基乙烯基醚的研究——3、四氟乙烯与-7,7-二氯-3-氧杂全氟庚烯-1的共聚反应及共聚物的转化

 研究了二个新的全氟烷基乙烯基醚7,7-二氯-3-氧杂全氟庚烯-1(M_0)和10,10-二氯-3,6-二氧杂全氟5-甲基癸烯-1(M₁)-与四氟乙烯(TFE)的共聚反应,聚合物的性质,并测定了TFE-M₀竞聚率。竞聚率的测定证明M₀较其它已报道的全氟烷基乙烯基醚的聚合活性都大。TFE-M₀共聚物通过化学反应可转化成相应的全氟羧酸甲酯树脂。     

Thermodynamic molecular switch in sequence‐specific hydrophobic interactions

This communication will demonstrate the existence of a thermodynamic molecular switch in the pairwise, sequence‐specific hydrophobic interaction of Ile–Ile, Leu–Ile, Val–Leu, or Ala–Leu over the temperature range of 273–333 K reported by Nemethy and Scheraga in 1962. Based on Chun's development of the Planck–Benzinger methodology, the change in inherent chemical bond energy at 0 K, ΔH°(T₀), is 3.0 kcal mol^?1 for Ile–Ile, 2.4 for Leu–Ile, 1.8 for Val–Leu, and 1.2 kcal mol^?1 for Ala–Leu. The value of ΔH°(T₀) decreases as the length of the hydrophobic side chain decreases. It is clear that the strength and stability of the hydrophobic interaction is determined by the packing density of the side chains, with Ala–Leu being the most stable. At 〈T_m〉, the thermal agitation energy, $\int^{T}_{0}\Delta Cp^{\circ}(T)\,dT$, is about five times greater than ΔH°(T₀) in each case. Additionally, the thermal agitation energy for the same series, evaluated at 〈T_m〉, decreases in the same order, that is, as the length of the side chain decreases. This pairwise, sequence‐specific hydrophobic interaction is highly similar in its thermodynamic behavior to that of other biological systems, except that the negative Gibbs free energy change minimum at 〈T_s〉 occurs at a considerably higher temperature, 355 K compared to about 300 K. The melting temperature, 〈T_m〉, is also high, 470 K compared to 343 K in a biological system. The implication is that the negative Gibbs free energy minimum at a well‐defined 〈T_s〉 has it origin in the hydrophobic interactions, which are highly dependent on details of molecular structure. In addition to the four specific dipeptide interactions described, we have shown in our unpublished work the existence of a thermodynamic molecular switch in the interactions of 32 dipeptides wherein a change of sign in ΔCp°(T)_reaction leads to a true negative minimum in the Gibbs free energy of reaction, and hence, a maximum in the related K_eq. Indeed, all interacting biological systems that we have thus far examined using the Planck–Benzinger approach point to the universality of thermodynamic molecular switches. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001     

Kinetic investigation of the textile bleaching process

Volumetric H₂-uptake measurements on an Mo₂N (79 m²g^–1) sample reduced at 673 K have been carried out and the uptake isotherms in the temperature range of 308–623 K have been determined. Both the total and reversible hydrogen uptake increased with the uptake temperature. The irreversible hydrogen uptake increased abruptly when the uptake temperature was raised up to 423 K. The maximum of irreversible hydrogen uptake was measured at 473 K. The H_IR/Mo ratio calculated from the uptakes obtained in the temperature range of 308–623 K varies in the range of 0.0010–0.0202. One possible mechanism for hydrogen adsorption is proposed to be heterolytic dissociation on Mo-N paris, in which the molybdenum atoms are in unsaturated coordination.     

水中矿物元素的ICP-MS分析

用ICP－MS对地下水、地表水和饮用水中的矿物元素进行了分析测定，实验证明用ICP－MS可以同时测定地下水，地表水和饮用水中矿物元素；该法灵敏度、精密度和准确度都能满足有关标准的要求，具有多元素同时分析，样品前处理简单，干扰少，测定快速，省事省力等优点。     

γ－芳基取代烯丙醇菊酯的合成及杀虫活性

γ－芳基取代烯丙醇菊酯的合成及杀虫活性陈亚娟，黄润秋，马军安（南开大学元素有机化学研究所，天津，３０００７１）关键词γ－芳基取代烯丙醇，拟除虫菊酯，杀虫活性第一个人工合成除虫菊酯烯丙菊酯保留了天然除虫菊酯醇部分的环戊烯醇酮结构，至今仍广泛用作卫生杀虫...     

MAA存在下VAc/BA核壳乳液聚合过程中的胶粒形态研究

用ＴＥＭ和电位滴定法对不同配方和工艺条件得到的胶粒形态结构和羧基分别进行了表征。结果表明：加入甲基丙烯酸有利于胶粒的稳定和形成规则的核壳胶粒。半连续加料不会形成完全反转的核壳结构,但是,核层在反应过程中由于聚合物簇的迁移会造成形变。由于胶粒中聚合物浓度高,粘度大,因而胶粒形态变化受动力学影响甚大,羧基分布主要是由动力学确定的。     

QuEChERS/超高效液相色谱-串联质谱法同时测定水产品中四溴双酚A与六溴环十二烷

建立了同时测定水产品中四溴双酚A(TBBPA)和六溴环十二烷(HBCD)的超高效液相色谱-串联质谱方法。样品前处理采用QuEChERS方法,均质生物样品用水分散后加乙腈提取,经C_(18)分散固相萃取净化。采用CORTECS~?C_(18)色谱柱(4.6 mm×100 mm×2.7μm)分离,以甲醇-水为流动相进行梯度洗脱,流速为0.7 mL/min。采用电喷雾离子源,在负离子模式下以多反应监测(MRM)方式检测。结果表明,TBBPA和3种HBCD单体在0.5～500μg/L范围内线性良好,相关系数(r)大于0.998,检出限(LOD,S/N=3)和定量下限(LOQ,S/N=10)分别为0.04～0.16μg/kg和0.12～0.55μg/kg。在5、20、50μg/kg加标水平下的平均回收率为74.0%～121%,相对标准偏差(RSD)为0.20%～23%。该方法操作简单、快速、重现性好,适用于水产品中TBBPA和HBCD的快速检测。     

La0.8Ca0.2MnO3纳米线的制备及表征

利用Sol-gel法结合氧化铝模板技术制备了La0.8Ca0.2MnO3纳米线, 并研究了两种热处理方法对 La0.8Ca0.2MnO3纳米线结构和形貌的影响. 快速升温到800 ℃得到的La0.8Ca0.2MnO3纳米线较粗, 其直径大于氧化铝模板的孔径, 而经过缓慢升温到400 ℃预处理再升温到800 ℃得到的La0.8Ca0.2MnO3纳米线, 其直径和氧化铝模板的孔径相当, 都约为35 nm. X射线衍射和透射电镜分析结果表明, 两种方法得到的 La0.8Ca0.2MnO3纳米线都是具有钙钛矿结构的属于单斜晶系的多晶材料.