EDTA and pH‐sensitive crosslinking polymerization of acrylic acid, 2‐acrylamidoglycolic acid,and 2‐acrylamide‐2‐methyl‐1‐propanesulfonic acid

Network formation was monitored by shear storage modulus (G′) during free radical crosslinking polymerization to investigate the effects of pH and ethylenediaminetetraacetic acid (EDTA; a complex agent). Three types of acrylic monomers, acrylic acid (AAc), 2‐acrylamidoglycolic acid (AmGc), and 2‐acrylamido‐2‐methyl propanesulfonic acid (AmPS), were polymerized in the presence of a crosslinking agent. The ratio of crosslinking agent (methylene bis‐acrylamide; MBAAm) to monomer was varied as: 0.583 × 10^?3, 1.169 × 10^?3, 1.753 × 10^?3, and 2.338 × 10^?3. G′ of the hydrogel in crosslinking polymerizations of AAc and AmPS was effectively increased by addition of EDTA, which was not the case for the crosslinking polymerization of AmGc. The order of magnitude of G′ differed based on the acidity of monomer. The maximum values of G′ in crosslinking polymerizations of AAc, AmGc, and AmPS were ～20,000 Pa, 6000 Pa, and 400 Pa, respectively. G′ varied linearly with the molecular weight between crosslinks (M_wc). pH and EDTA‐complex affected the rate of intramolecular propagation during crosslinking polymerization. Our results indicated that G′ was primarily affected by the following factors in the order: (1) acidity of monomer, (2) M_wc, and (3) physical interactions induced by pH and EDTA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41026.     

浅谈无机化学中原子结构对化合物性质影响

原子结构及分子结构是无机化学教学中的重难点。文章通过碳、硅原子结构的对比,讨论了原子结构对分子结构的影响,并决定分子性质。这不但有利于提高学生的学习兴趣,而且有益学生系统掌握原子和分子结构。     

化学教学中电子课件的字体图片编辑实用技巧

青年教师在刚开课时需要制作多媒体课件,其素材来源很多,导致在制作课件时经常遇到字体不统一和图片不美观等问题,文章提供了几个修改字体和美观图片的小技巧,如利用宏可以一次性修改好课件中绝大多数文字字体。     

基于余热回收的燃气热泵系统高温制热特性

燃气热泵（GHP）是一种先进的低碳节能清洁供暖技术。针对当前GHP技术研究中普遍使用的R134a冷媒制热环境温度下限偏高及活塞式压缩机能效偏低等局限,本文创新性地搭建了基于使用R410A冷媒涡旋式压缩机的高能效GHP实验平台,在实验台上进行了不同出水温度（t_w,out）、发动机转速（N_eng）、进水流量（G_w）及是否余热回收下的高温制热特性研究,得到了制热量（Q_h）、耗气功率（P_gas）、压机功率（P_comp）、一次能源利用率（PER）及性能系数（COP）的变化规律,并对关键性能参数进行了误差分析。结果表明,t_w,out由41℃增至50℃时,Q_h、PER和COP分别减小了3.12%、13.17%和18.92%,PER下降的幅度明显小于COP;N_eng从1200r/min增至1800r/min时,在50℃出水下Q_h、P_gas与P_comp分别增加了51.03%、43.98%和55.37%,PER因受到发动机有效热效率升高的影响而增加了4.90%;G_w从5.8m³/h增至11.5m³/h时,系统各性能参数随G_w变化不敏感;系统考虑余热回收后,Q_h、PER与COP均显著增加,在N_eng为1200r/min且41℃出水下分别增加了31.18%、36.06%与31.54%,系统余热回收量占总制热量和发动机总余热量的比例分别为17.48%~24.54%和44.16%~63.39%。由误差分析可得Q_h、P_gas和PER的误差分别为3.29%、1.00%和3.44%,表明了系统测试结果具有较高的准确度。     

新型数码电子雷管及其起爆系统的开发与应用

针对现有数码电子雷管及其起爆系统在爆破作业现场使用中存在操作不便、输入延期时间繁琐和易错的问题,通过炮孔定位和数据采集技术,研发了新型数码电子雷管及其起爆系统。在使用过程中,可识别炮孔位置,自动匹配炮孔和雷管编号,自动写入延期时间,快速建立炮孔位-雷管ID码-延期时间三者的关系,各功能独立分开,但又相互配合,减少了误操作,提高了爆破作业现场自动化水平,增强了新型数码电子雷管起爆系统的安全性和可操作性。     

不同pH对焦磷酸铵水解的影响

以主成分为焦磷酸铵的水溶性聚磷酸铵为实验原料，设置8.2、6.0、4.0、3.5、3.0、2.5、2.0等7组pH梯度，系统研究了酸度对焦磷酸铵水解的影响。结合一级反应动力学方程与阿累尼乌斯方程进行焦磷酸铵的水解动力学计算，结果表明：经过310 d（第二批260 d）的放置，pH从8.2降低到2.0时焦磷酸铵质量分数从初始态的92.6%依次减少为85.4%、51.2%、50.6%、50.2%、24.3%、12.9%和6.0%。焦磷酸铵在自然温度下的水解速率随着pH的降低而不同程度地加快，服从一级反应机理。pH从8.2降低到2.0时焦磷酸铵的水解速率常数从2.92×10-4~3.43×10-4增加至3.41×10-3~1.47×10-2，二者相差10~40余倍，对应半衰期为50~2 000 d。秋冬与春夏两时段的水解速率差异很大，二者水解速率常数相差1.17~4.32倍，焦磷酸铵的水解活化能为7.5~68.5 kJ/mol。     

“一带一路”国家黑色金属、有色金属冶炼加工产业合作优选评价

"一带一路"倡议为我国企业走出去合作提供了良好契机。为了我国企业与"一带一路"国家更好地开展黑色金属、有色金属的产能合作,本文从投资环境、冶炼加工产业合作基础、市场需求前景以及地缘战略意义四个方面建立了三层冶炼加工产能合作优选评价指标。通过对各国各项指标对比赋值,利用特征值分析法,得到了"一带一路"沿线中的62个国家的评价结果,并将其分为最适宜投资国、较适宜投资国、一般投资国和谨慎投资国四类,以期为我国企业展开有利的产能合作提供指导。     

A novel application of electrospinning technique in sublingual membrane: characterization,permeation and in vivo study

Isosorbide dinitrate–polyvinylpyrrolidone (ISDN–PVP) electrospinning fibers were formulated and explored as potentially sublingual membrane. The addition of polyethylene glycol (PEG) to the formulation improved flexibility and reduced fluffiness of the fiber mat. The scanning electron microscopy (SEM) demonstrated that the fibers tended to be cross-linking, and the crosslinking degree increased with the increase of PEG amount. The differential scanning calorimetry (DSC) indicated that ISDN existed in non-crystalline state in the fibers (except at the highest drug content). The infrared spectroscopy suggested that ISDN had better compatibility with the ingredients owing to the hydrogen bonding (or hydrophobic interactions). The fibers were highly favorable for the fabrication of sublingual membrane due to neutral pH, large folding endurance and rapid drug release (complete dissolution within 120 s). The permeation study of ISDN through both dialysis membrane (DM) and porcine sublingual mucosa (SM) were carried out. A significant relationship of drug permeation rate through DM and SM was built up, which indicated that DM could be used to partly simulate SM and assess formulation. The pharmacokinetic study in rats demonstrated that the electrospinning fiber membrane had a higher C_max and lower T_max compared to the reference preparation, and the relative bioavailability of the fiber membrane was 151.6%.     

改性大豆蛋白胶黏剂的酸化效应

以浓硫酸为酸化剂，探讨改性大豆蛋白胶黏剂的酸化处理效应。结果表明：随pH值的降低，改性大豆蛋白胶黏剂的颜色逐渐变浅，黏度先逐渐上升再急速下降，胶合强度则先下降后上升。采用酸化处理可明显改善改性大豆蛋白胶黏剂的颜色和流变性能，且不影响其胶合性能。     

毛细管气相色谱法分析液化石油气中二甲醚含量

通过恒温水浴完全气化样品,建立了用毛细管气相色谱法测定液化石油气中二甲醚含量的方法。采用PLOT/Q（30 m×0.53 mm×40μm）毛细管柱,以热导池检测器检测,氦气为载气,以面积校正归一化法计算二甲醚含量。结果表明,该方法操作简单,实用性强,重复性好,可以用于液化石油气中二甲醚含量的分析。