A spectroscopic study of the self-association and inter-molecular aggregation behaviour of pH-responsive poly(l-lysine iso-phthalamide)

The pH mediated intra-molecular association and inter-molecular aggregation of a range of amphiphilic poly(l-lysine iso-phthalamide) polymers have been investigated in aqueous solution over a range of pH values and concentrations. The desired functionality of these novel bioresponsive amphiphilic polymers was achieved by incorporating pendant hydrophilic carboxyl groups along the polymer backbone, via the l-lysine moiety, balanced by a degree of hydrophobicity introduced via the iso-phthaloyl moiety. Incorporation of low levels of bis-functional Cy3 (poly-Cy3) and/or Cy5 dye (poly-Cy3/5 or poly-Cy5) co-monomers in the responsive polymer backbone allowed detailed probing of the pH mediated hydrophobic association using a combination of optical spectroscopic techniques. Both steady-state fluorescence spectroscopy and fluorescence lifetime measurements of poly-Cy3 revealed a conformational transition at pH 4.5. Thus, below a critical pH the polymer collapsed into a compact globular structure (hypercoil) bringing the fluorophore molecules into close proximity with one another. This resulted in a dramatic reduction in fluorescence intensity and fluorescent lifetime in the single fluorophore systems (poly-Cy3) accompanied by a red shift in the maximum emission wavelength. Observed redshifts in the emission maxima and enhancements of fluorescent lifetimes with increasing polymer concentration suggested the formation of polymer aggregates. Fluorescence resonance energy transfer (FRET) was measured in mixtures of single fluorophore containing poly-Cy3 (donor) and poly-Cy5 (acceptor) and dual fluorophore containing poly-Cy3 (donor)/Cy5 (acceptor) in an effort to distinguish between intra-molecular versus inter-molecular association. The relevance of the results with respect to potential in vivo applications (drug delivery and biodiagnostics) is discussed.     

使用毛细管电泳定量分析黑白显影液衰退反应中的对苯二酚和对苯二酚单磺酸盐

使用毛细管电泳分离并定量分析了对苯二酚——— 1种黑白显影液中的显影剂和它的衰退反应产物对苯二酚单磺酸盐。优化了的毛细管电泳分离。     

Synthesis and characterization of cleavable surfactants derived from poly(ethylene glycol) monomethyl ether

A series of noncyclic acetal-linked cleavable surfactants were simply prepared by condensation of aldehydes with poly(ethylene glycol) monomethyl ethers. All of the products were characterized by¹H nuclear magnetic resonance. Their hydrophile-lipophile balance, surface tension, cloud point, critical micelle concentration, and foam height were determined. Hydrolysis kinetic studies, followed by gas chromatography, showed that they had higher hydrolytic reactivity in acidic solution than cyclic acetal-linked cleavable surfactants.     

UCC项目靠的是天时地利人和——访中国建材装备有限公司总经理方芳

装备公司是我国最早走向国际市场的水泥设备供应商,上世纪90年代初,由装备公司出口马来西亚的日产2000吨水泥成套设备项目,是我国当时出口的单线规模最大的生产线;1993年到1996年,出口巴基斯坦两条日产2000吨的幸运水泥厂,又是当时我国出口最大规模的水泥厂。     

Catalytic activities and properties of mesoporous sulfated Al2O3–ZrO2

Mesoporous sulfated Al₂O₃–ZrO₂ (MSAZ) catalysts with large surface areas and pore volumes after calcination at high temperature (650 °C) and with higher Al₂O₃ content than 20wt% were successfully prepared from a template of block copolymer (P84). The MSAZ catalysts were characterized by X-ray diffraction (XRD), N₂ adsorption, transmission electron microscopy (TEM), ²⁷Al magic-angle spinning nuclear magnetic resonance (MAS NMR), thermogravimetric analysis (TG–DTG), temperature-programmed desorption of ammonia (NH₃-TPD) and infrared spectra (IR) of adsorbed pyridine. It is shown that the resulting mesostructured sulfated Al₂O₃–ZrO₂ samples have a well-developed textural mesoporosity. The number of acid sites present on MSAZ catalysts is higher than that on conventional sulfated zirconia, and the former catalysts are more active than the latter one for various acid-catalyzed reactions.     

利用高铝矾土研制低温耐磨氧化铝瓷

着重介绍了以高铝矾土为主要原料的85瓷的合理配方和所采用的生产工艺，并对吸水率、体积密度、耐磨性、显微硬度、抗折强度和断裂韧性等物理性能进行了测试。还探讨了低温烧成机理、提高耐磨性的途径。结合显微结构分析了生产工艺对产品性能的影响。     

去酸水用于钠离子交换树脂再生试验

根据离子交换原理，利用纺丝去酸水代替食盐、芒硝再生钠离子交换树脂，可以去除硬水中的钙离子和镁离子。再生阴床排出碱性废水加入去酸水中，可降低去酸水酸度，提高出水pH，出水水质达到软化水水质标推。用去酸水再生，可减少污染，降低纺丝工艺排水酸度，具有明显的社会效益和经济效益。     

PVC-U异型材塑化度的评价

比较了4种评价PVC-U塑化度的方法:目测法简单;溶剂法迅速,容易操作;拉伸法可定量判断,但需要大量样品;DSC法准确、方便。     

时间Petri网与CAGA算法相结合的并行测试研究

在并行测试的研究中对于任务的测试次序一直是个研究重点及难题。用时间Petri网建立关于并行测试系统的模型,并首次用元胞遗传算法(CAGA)对模型中的变迁序列进行搜索,快速得到最好的测试序列。通过仿真结果表明,该算法展示了很好的收敛效果,并且与已有的研究成果相比更具优势。     

压痕法确定纤维复合材料界面影响区蠕变特性的数值模拟法

研究由平头压痕蠕变试验来确定纤维复合材料界面影响区蠕变性能参数的可行性。利用有限元蠕变分析确定在定压痕应力下的压痕蠕变率，重点放在稳定压痕蠕变率和复合材料材料界面影响区的蠕变性能参数的关系上。计算结果表明，界面影响区的剪应力沿纤维轴向在蠕变的主要过程中均匀分布，并且保持不变；详细地研究了压头大小对压痕蠕变响应的影响：提出两种方法由压痕蠕变试验来确定界面影响区蠕变性能参数，并给出了算例。这些结果也有利于准确认识平头压痕蠕变试验从而拓宽其应用范围。