Non‐destructive analysis using PXRF: methodology and application to archaeological ceramics

Uncritical application of portable X‐ray fluorescence (PXRF) to non‐destructive analysis of archaeological ceramics has been received with scepticism. In this article, we present a methodological evaluation of the parameters and constraints for PXRF analysis of archaeological ceramics. We use experimental matrices that simulate characteristics of archaeological artefacts to demonstrate the impact of (1) surface morphology, (2) organic surface coatings and (3) grain size and mineralogy on non‐destructive PXRF analysis. We then apply these parameters to PXRF analysis of heterogeneous handmade ceramics from central Turkey. We conclude that with appropriate methodology, non‐destructive PXRF analysis can be demonstrated to provide a high level of accurate and precise geochemical discrimination for archaeological ceramics. Copyright © 2011 John Wiley & Sons, Ltd.     

Copolymerization of Metal Nanoparticles: A Route to Colloidal Plasmonic Copolymers

The resemblance between colloidal and molecular polymerization reactions is very useful in fundamental studies of polymerization reactions, as well as in the development of new nanoscale systems with desired properties. Future applications of colloidal polymers will require nanoparticle ensembles with a high degree of complexity that can be realized by hetero‐assembly of NPs with different dimensions, shapes, and compositions. A method has been developed to apply strategies from molecular copolymerization to the co‐assembly of gold nanorods with different dimensions into random and block copolymer structures (plasmonic copolymers). The approach was extended to the co‐assembly of random copolymers of gold and palladium nanorods. A kinetic model validated and further expanded the kinetic theories developed for molecular copolymerization reactions.     

Explorations of catalytic domains in non-ribosomal peptide synthetase enzymology

Covering up to the end of 2011Many pharmaceuticals on the market today belong to a large class of natural products called nonribosomal peptides (NRPs). Originating from bacteria and fungi, these peptide-based natural products consist not only of the 20 canonical l-amino acids, but also non-proteinogenic amino acids, heterocyclic rings, sugars, and fatty acids, generating tremendous chemical diversity. As a result, these secondary metabolites exhibit a broad array of bioactivity, ranging from antimicrobial to anticancer. The biosynthesis of these complex compounds is carried out by large multimodular megaenzymes called nonribosomal peptide synthetases (NRPSs). Each module is responsible for incorporation of a monomeric unit into the natural product peptide and is composed of individual domains that perform different catalytic reactions. Biochemical and bioinformatic investigations of these enzymes have uncovered the key principles of NRP synthesis, expanding the pharmaceutical potential of their enzymatic processes. Progress has been made in the manipulation of this biosynthetic machinery to develop new chemoenzymatic approaches for synthesizing novel pharmaceutical agents with increased potency. This review focuses on the recent discoveries and breakthroughs in the structural elucidation, molecular mechanism, and chemical biology underlying the discrete domains within NRPSs.     

用ZEMAX软件辅助迈克耳孙干涉仪实验教学

利用ZEMAX软件设计了迈克耳孙干涉仪实验光路.软件绘制的不同显示方式的实验光路外形图,使学生对实验光路建立起了清晰的图像.通过编写ZPL程序实现了对实验现象的动态模拟,使学生对理想情况下的实验现象有一个准确的把握.通过在软件中改变光路主要参数分析了不同方面和不同程度的误差对干涉条纹的影响,其结论对学生在实验中进行有效而准确的调节起到了指导作用.     

以香豆素为基用以识别氟离子的新型比色化学传感器

以香豆素作为发色团,胺基为氢键供体,以—C=N键桥连设计合成了可裸眼识别氟离子的化学传感器1,吸收光谱结果表明在乙腈中它可以高选择性识别氟离子,光谱红移70 nm,溶液颜色由橙色变为蓝紫色,而其它离子如Cl~-、Br~-、I~-、H_2PO_4~-、NO_3~-、HSO_4~-、AcO~-等均不影响其对氟离子的识别.通过核磁共振氢谱考察其识别机制,表明传感分子通过与F~-间的质子转移反应,使整个体系电子离域,分子内电荷转移更加显著,从而导致吸收光谱大幅红移.     

Holz, Cellulose und Cellulosederivate

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