The influence of chemical structure on the antimicrobial activities of thiosemicarbazone-chitosan

We have previously reported the preparation of acetyl and benzoyl phenyl-thiosemicarbazone derivatives of chitosan and their antimicrobial activities. The purpose of this study was to further assess the relationship between chemical structure and antimicrobial activity of chloracetyl phenyl-thiosemicarbazone-chitosan. Ten new chloracetyl phenyl-thiosemicarbazone-chitosans were prepared, and their structures were characterized using FT-IR and elemental analysis. The synthesized compounds were tested against four species of bacteria and four crop-threatening pathogenic fungi. Different molecular weights and concentrations were evaluated. The antifungal activities of the synthesized compounds were related to the positive polarity of the N₄ atom and the distribution of the electron atmosphere in the C=S group. All chitosan compounds had inhibitory effects when tested with bacteria. The minimum MIC and MBC with Escherichia coli were 7.03 and 56.25 μg mL^?1, respectively.     

Tough nanocomposite hydrogels from cellulose nanocrystals/poly(acrylamide) clusters: influence of the charge density,aspect ratio and surface coating with PEG

Cellulose-derived materials are usually characterized by sophisticated structures, leading to unique and multiple functions, which have been a source of inspiration for the fabrication of a wide variety of nanocomposites. Cellulose nanocrystals/poly(acrylamide) (CNCs/PAM) nanocomposite hydrogels were synthesized via in situ polymerization in the CNC suspension. The cellulose from pulp fiber under different sulfuric acid hydrolysis conditions, examined by conductometric titration and transmission electron microscopy, was applied to study how the effects of the surface charge and aspect ratio affect CNCs’ mechanical reinforcement in nanocomposites. The results indicated that the higher surface charge concentration resulted in better dispersibility in aqueous suspension, leading to a more efficient energy dissipation process. The CNC reinforcement behavior followed the percolation model where the greater aspect ratio of CNC contributed to higher mechanical properties. The preferential adsorption of poly(ethylene glycol) (PEG) on the CNC surface was characterized by zeta potential measurements where the fracture strength and fracture elongation of nanocomposites decreased with increasing PEG concentration. The adsorption of PEG on the CNC surface occupied the active sites for polymer chain propagation, which hindered the PAM cross-linking effect on the CNC surface and decreased the cross-linking density of the network.     

Novel hydrothermal carbonization of cellulose catalyzed by montmorillonite to produce kerogen-like hydrochar

The conversion of cellulose to petroleum-like fuel is a very challenging yet attractive route to developing biomass-to-fuel technology. Many attempts have been made in liquefaction, pyrolysis and gasification of cellulose to produce fuels or intermediate chemicals. Previous studies indicate that these processes are tough. Hence, the present work is concerned with the development of new technologies for the conversion of cellulose into materials which are analogies to the precursor of petroleum. Montmorillonite-catalyzed hydrothermal carbonization of microcrystalline cellulose for the production of kerogen-like hydrochar under mild conditions was investigated. It was revealed that the hydrothermal carbonization of microcrystalline cellulose alone resulted in hydrochar with type III kerogen-like structure, whereas in the presence of montmorillonite, the hydrothermal carbonization of microcrystalline cellulose yielded a hydrochar-mineral complex, of which the isolated organic fraction was oil-prone type II kerogen-like structure. Results suggested that further improved montmorillonite-aided biomass conversion to more oil-prone kerogen-like solid products could be an alternative efficient route to obtain biofuel and chemicals.     

超高效液相色谱-串联质谱法测定辣椒制品中酸性橙Ⅱ

建立了辣椒制品中酸性橙Ⅱ的超高效液相色谱-串联质谱分析方法。样品用乙腈提取,WAX弱阴离子固相萃取柱净化浓缩,经超高效液相色谱分离,三重四极杆质谱电喷雾电离(ESI),负离子多反应监测模式检测。结果表明,在1~200ng/mL质量浓度范围内,线性相关系数大于0.998;加标回收率为83.2%~113.2%,相对标准偏差为0.7%~7.2%。检出限分别为1.0μg/kg(辣椒油及辣椒酱)和2.0μg/kg(辣椒粉)。方法适用于辣椒制品中酸性橙Ⅱ的测定。     

GC-NCI/MS法分析海水中得克隆类物质

建立了固相萃取-气相色谱-负化学源质谱联用法(SPE-GC-NCI/MS)同时测定海水中5种得克隆类物质的方法。采用二氯甲烷进行液液萃取(LLE),萃取液经过硅胶固相萃取小柱净化后,在15 m长的DB-5HT高温毛细管气相色谱柱上分离,NCI/MS以选择离子监测模式检测目标化合物。方法中5种得克隆类物质Dec 602,Dec 603,Syn DP和Anti DP的检出限分别为0.01,0.01,0.08,0.02和0.01 ng/L,平均加标回收率分别为61%,75%,75%,87%和91%,RSD均小于5.1%。采用该法对河北近岸海域16个采样站位海水样品进行分析,所有采样站位均有得克隆类物质检出。     

分子动力学模拟研究[Bmim][PF_6]+水+醇三元体系的微观结构和分子间相互作用(英文)

研究离子液体体系的微观结构和分子间相互作用具有重要意义.本文对1-丁基-3-甲基咪唑六氟磷酸盐([Bmim][PF6])+水+乙醇和[Bmim][PF6]+水+异丙醇三元体系进行了分子模拟研究,计算了径向分布函数和不同组成的水-醇混合溶剂与离子液体阴阳离子间的相互作用能,并将其分解为库仑相互作用能和Lennard-Jones(LJ)势能.在此基础上,研究了溶液体系的微观结构、分子间相互作用和相行为.结果表明,水倾向于与离子液体阴离子和阳离子极性部分作用,醇倾向于与阴离子和阳离子非极性部分作用;库仑力主导阴离子-溶剂相互作用,色散力主导阳离子-溶剂相互作用,阴阳离子的缔合状态对色散力影响较小,对库仑力的影响非常显著.     

高活性硫化铅电极的制备及在量子点敏化太阳能电池中的应用

为了提高量子点敏化纳晶薄膜太阳能电池的光电转换效率,我们通过连续在酸和多硫溶液中处理铅片制备了对多硫电解液具有高电催化活性的硫化铅电极.通过电化学阻抗谱测试评价所制备硫化铅电极的催化活性,从而确定制备高效硫化铅电极的最佳条件.以在最佳条件下制备的硫化铅为对电极、CdSe量子点敏化TiO2纳晶薄膜为工作电极和多硫电解液组装成量子点敏化太阳能电池.光电性能测试结果表明所制备的电极具有良好的催化活性和光电转换性能.与已报导的方法相比,新方法大幅度地减少制备过程所需的时间,但却提高了所制备的硫化铅对电极的催化活性.通过X射线衍射和扫描电镜测试表征了硫化铅的生成过程,探讨了催化活性提高的原因.     

Exceedingly Fast Copper(II)‐Promoted ortho CH Trifluoromethylation of Arenes using TMSCF3

The direct ortho‐trifluoromethylation of arenes, including heteroarenes, with TMSCF₃ has been accomplished by a copper(II)‐promoted C? H activation reaction which completes within 30 minutes. Mechanistic investigations are consistent with the involvement of C? H activation, rather than a simple electrophilic aromatic substitution (S_EAr), as the key step.     

Immuno‐Chemotherapeutic Platinum(IV) Prodrugs of Cisplatin as Multimodal Anticancer Agents

There is growing consensus that the clinical therapeutic efficacy of some chemotherapeutic agents depends on their off‐target immune‐modulating effects. Pt anticancer drugs have previously been identified to be potent immunomodulators of both the innate and the adaptive immune system. Nevertheless, there has been little development in the rational design of Pt‐based chemotherapeutic agents to exploit their immune‐activating capabilities. The FPR1/2 formyl peptide receptors are highly expressed in immune cells, as well as in many metastatic cancers. Herein, we report a rationally designed multimodal Pt^IV prodrug containing a FPR1/2‐targeting peptide that combines chemotherapy with immunotherapy to achieve therapeutic synergy and demonstrate the feasibility of this approach.     

Gold‐Catalyzed 1,2‐Acyloxy Migration/Intramolecular [3+2] 1,3‐Dipolar Cycloaddtion Cascade Reaction: An Efficient Strategy for Syntheses of Medium‐Sized‐Ring Ethers and Amines

A highly efficient strategy for the formation of medium‐sized‐ring ethers and amines based on a gold‐catalyzed cascade reaction, involving enynyl ester isomerization and intramolecular [3+2] cyclization, has been developed. Various multisubstituted medium‐sized‐ring unsaturated ethers and amines were obtained through this transformation. This method represents one of the relatively few transition metal catalyzed intramolecular cycloaddition reactions for medium‐sized ring synthesis.