Synthesis and characterization of an amphiphilic chitosan bearing octyl and methoxy polyethylene

An amphiphilic N-octyl-O-methoxy poly (ethylene glycol) chitosan was successfully prepared by grafting successively octyl groups onto amino groups at chitosan’s C-2 position as hydrophobic moieties and methoxy polyethylene glycol (MPEG) groups onto hydroxyl groups at C-6, C-3 as hy-drophilic ones. A certain amount of -NH2 was retained in the structure of chitosan derivatives through protection by phthalic anhydride. The chemical structures and degree of N-and O-substitution of chitosan derivatives were characterized by FTIR, 1H NMR, GPC and elemental analysis, respectively. The amphiphilic property for convenient self-assembly and the preserved -NH2 groups for progressive chemical cross-linking make the resultant Nocyl-O-MPEG chitosan soluble in water and potentially applicable in preparing stable chitosan hollow microspheres, a demanding drug-carrier in medical and pharmaceutical sciences.

气敏新材料MXenes在呼出气体传感器中的应用

电子鼻结合人工智能对呼出气进行检测、分析和识别已成为非侵入性医疗检测领域的研究热点。然而,目前已报道的气体传感材料尚不能同时满足高灵敏度、高选择性和稳定的室温检测,阻碍了气体传感器在医疗健康领域的应用及发展,寻找合适的传感材料具有重要的意义和挑战。新型二维层状纳米材料MXenes具有种类多、比表面积大、导电性能强、表面含有丰富的官能团以及能带宽度可调等优异性能,是高灵敏、低能耗气体传感器的明星候选材料。本综述针对MXenes基材料的特殊结构,总结梳理了MXenes基材料在气体传感中的最新研究成果,聚焦于MXenes材料的气体传感机理和改性方法,对MXenes材料用于气体传感依然存在的问题和挑战进行深入探讨。

Cationic content effects of biodegradable amphoteric chitosan-based flocculants on the flocculation properties

A series of biodegradable amphoteric chitosan-based flocculants （3-chloro-2-hydroxypropyl trimethyl ammonium chloride （CTA） modified carboxymethyl chitosan, denoted as CMC-CTA） with different substitution degrees of CTA were prepared successfully. The content of carboxymethyl groups in each CMC-CTA sample was kept almost constant. The solubility of the various flocculants showed that, higher cationic content of flocculants caused a better solubility. The flocculation experiments using kaolin suspension as synthetic water at the laboratory scale indicated that the substitution degree of CTA was one of the key factors for the flocculation properties. With the increase of cationic content, the flocculants were demonstrated better flocculation performance and lower dosage requirement. Flocculation kinetics model of particles collisions combining zeta potential and turbidity measurements was employed to investigate the effects of the cationic content of the flocculants on the flocculation properties from the viewpoint of flocculation mechanism in detail. Furthermore, flocculation performance using raw water from Zhenjiang part of Yangtze River at the pilot scale showed the similar effects to those at the laboratory scale.

MtROP8 is involved in root hair development and the establishment of symbiotic interaction between Medicago truncatula and Sinorhizobium meliloti

Emerging evidence has demonstrated that ROP GTPases play important roles in symbiosis,but the molecular mechanisms on their regulation in symbiosis are largely unknown.In this study,we showed that MtROP8 is involved in the symbiotic interaction between Medicago truncatula and Sinorhizobium meliloti.Expression analyses showed that MtROP8 was down-regulated in the early infected roots,but significantly up-regulated in nodules compared to the roots.Phenotypic analysis of RNA interference(RNAi)-mediated silencing of MtROP8 revealed that knock-down of MtROP8 expression resulted in various developmental defects of root hairs,including branched hairs,short bulbous root hairs,and even root hairs with apparent swollen bases,which were caused by the modification of the distribution and the levels of reactive oxygen species(ROS).Moreover,infection events were increased in transgenic roots harboring the MtROP8 RNAi construct in response to S.meliloti inoculation,concomitant with enhanced nodulation.These results indicate that MtROP8participates in root hair development and the establishmentof the symbiotic interaction by regulating ROS production and distribution.

妊娠期内分泌干扰物暴露与4、5岁儿童的社会交往、重复性和刻板性行为:HOME研究

[背景]内分泌干扰物(EDCs)可能是泛自闭症障碍症候群的病因,但是要在内分泌干扰物的混合物中确定相关的化学物颇为困难。[目的]确定与自闭症行为相关的妊娠期EDC暴露。[方法]测定俄亥俄州辛辛那提市进行的健康结局与环境措施(Health Outcomes and Measures of the Environment,HOME)研究中175名孕妇的血液或尿液样本中8种邻苯二甲酸酯代谢物、双酚A、25种多氯联苯(PCBs)、6种有机氯杀虫剂、8种溴化阻燃剂、以及4种全氟烷基物质的浓度。在其儿童4岁和5岁时,由母亲完成社会反应量表(SRS)——这是一个针对自闭症行为的测量量表。采用两阶段分层分析,探讨调整混杂因素后,52种内分泌干扰物与SRS得分之间的相关性,以解释相互关联的EDCs的重复测量以及混杂影响。[结果]大部分EDCs与可忽略不计的SRS得分绝对差(≤1.5)呈现相关性。多溴联苯醚-28(PBDE-28)(β=2.5;95%CI:-0.6~5.6)或反式九氯(β=4.1;95%CI:0.8~7.3)的血清浓度每增加一个2-SD,则与更多的自闭症行为相关。相对未检测到者而言,在那些检测到有PCB-178(β=-3.0;95%CI:-6.3~0.2)、β-六氯环己烷(β=-3.3;95%CI:-6.1^-0.5)和PBDE-85(β=-3.2;95%CI:-5.9^-0.5)的妇女所生的儿童中,自闭症行为较少。全氟辛酸(PFOA)浓度增加也与自闭症行为较少相关(β=-2.0;95%CI:-4.4~0.4)。[结论]在这个队列研究中,某些EDCs与自闭症行为,但研究样本量有限,从而无法排除那些无相关性的化学物。PFOA、β-六氯环己烷、PCB-178、PBDE-28、PBDE-85和反式九氯作为与儿童自闭症行为相关的因素,值得进行更仔细研究。