Determination of traces of fluorine or sulfur by x-ray analysis

New X-ray methods have been developed for the determination of as little as 1 μg of fluorine or as little as 0.1 μg of sulfur. Fluorine as fluoride is precipitated as lanthanum fluoride in 75% ethanol-water mixture and determined by measuring the amount of lanthanum present in the precipitate. Sulfur as sulfate is precipitated as barium sulfate from a barium sulfate saturated 50% ethanol-buffer mixture, using selenate as a coprecipitant, and determined by measuring the amount of sulfur present. Sulfur as sulfide is precipitated as cadmium sulfide and determined by measuring the amount of sulfur or cadmium in the precipitate.     

Macromolecular chemistry and medicine

Macromolecular substances are used in medicine both as materials and as reagents. In the former category polymers serve as replacements for soft tissue, as cardiovascular and orthopedic implants, and as adhesives. When employed as reagents, macromolecules interact with living tissue and play an active part in bodily repair processes.     

咪草烟分子印迹聚合物的制备及其选择性吸附性能的研究

以丙烯酸为聚合单体,TMPTA为交联剂,AIBN为引发剂,咪草烟为模板分子,采用在低温光聚合的方法,制备了对咪草烟分子具有选择性识别能力的分子印迹聚合物．通过IR和HPLC表征,咪草烟分子印迹聚合物对咪草烟分子具有良好的识别作用．     

三明治式双极膜的制备及其光催化性能

以Cr3+交联羧甲基纤维素钠(CMC)作为阳膜层,戊二醛改性壳聚糖(CS)作为阴膜层,纳米TiO2光催化剂作为双极膜的中间层,在TiO2上涂布光敏剂八羟基喹啉（Oxine）以增强其光催化解离水的性能,制备了三明治式的双极膜（mCMC/TiO2-Oxine/mCS BPM)。 该双极膜在紫外光照射下,具有高的水解离效率,优良的亲水性能,双极膜阻抗小,工作电压低,当工作电流密度达0.12 A/cm2时,电槽工作电压小于5.0 V。     

Controlled release of volatiles under mild reaction conditions: from nature to everyday products

Volatile organic compounds serve in nature as semiochemicals for communication between species, and are often used as flavors and fragrances in our everyday life. The quite limited longevity of olfactive perception has led to the development of pro-perfumes or pro-fragrances--ideally nonvolatile and odorless fragrance precursors which release the active volatiles by bond cleavage. Only a limited amount of reaction conditions, such as hydrolysis, temperature changes, as well as the action of light, oxygen, enzymes, or microorganisms, can be used to liberate the many different chemical functionalities. This Review describes the controlled chemical release of fragrances and discusses additional challenges such as precursor stability during product storage as well as some aspects concerning toxicity and biodegradability. As the same systems can be applied in different areas of research, the scope of this Review covers fragrance delivery as well as the controlled release of volatiles in general.     

Enzyme-based biocatalysis for the treatment of organic pollutants and bioenergy production

Enzyme-based biocatalysis is emerging as an advanced technique to develop green processes that help to maintain the sustainability of the environment. The bioremediation of toxic organic pollutants and waste to bioenergy production using enzymes as biocatalysts is rapidly growing due to its eco-friendly and sustainable nature. Additionally, a range of microbial species that typically grow on organic wastes can be used to produce these enzymes in an efficient manner. This is seen as a potential strategy for the development of cost-effective manufacturing for a number of biotechnological applications. The present study discusses biocatalysis as a promising and sustainable method toward the bioremediation of hazardous organic pollutants as well as for bioenergy production, based on the immense potential of enzymes as biocatalysts. Emphasis has been placed on evaluating the critical elements that can enhance the production of enzymes used as biocatalysts, as well as their functional effectiveness and stability.     

Polylactic acid (PLA) synthesis and modifications: a review

This article reviews various methods of synthesizing polycondensation and ring-opening polymerization and modifying properties of polylactic acid (PLA), which may be used as biomaterials, such as a drug carrier in a drug delivery system, as a cell scaffold and suture in tissue engineering, and as packaging materials in packaging engineering field. Copolymerization of lactide with other monomers or polymers such as malic acid, polyethylene glycol (PEG), polyglycolic acid (PGA), or dextran, as well as blending polylactide with natural derivatives and other methods of modification are discussed. Surface modifications of PLA-type copolymers, such as surface coating, chemical modification, and plasma treatment are described.     

Dithiocarbamates as Precursors in Organic Chemistry; Synthesis and Uses

Abstract

Organic dithiocarbamates have received great attention due to their interesting chemistry and wide utility as radical precursors and intermediates in organic synthesis. They also have found many of applications, that is, in agriculture and medicine. They are in use as pesticides, as well as in the rubber industries as vulcanization accelerators; and as antioxidants. Because they exhibit strong metal-binding capacity, they can act as in inhibitors of enzymes and have a profound effect on biological systems. Moreover, they have found application in the treatment of cancer and HIV.     

新型全息用光致聚合物的研究

研制了一种新型全息用光致聚合物材料,其成膜树脂为胺固化环氧体系,全息记录组分为光引发自由基聚合体系.用新合成的高效光敏染料DEAMC做光敏剂,通过配方调整,制备了一系列的样片,以457 nm的蓝光为记录光,632.8 nm的红光为探针光,研究了样片的衍射效率、灵敏度、折射率调制度等全息性能.结果表明,通过调整材料的配方组成、各组分的含量及样片的膜厚等因素,可以优化样片的全息性能.对样片的信噪比损失(LSNR)测试结果表明,在全息存储的曝光量范围内对样片曝光引起的图像信噪比损失仅有0.40 dB,说明样片的光学质量高,在全息存储上将具有很好的应用前景.     

双氧水氧化环己烯催化合成己二酸研究进展

评述了近年来以环己烯为底物,双氧水为氧源,分别采用钨酸盐、钨酸、杂多酸及杂多酸盐、功能化分子筛和负载离子液体等为催化剂催化合成己二酸的研究进展.     

Chemical reaction and Soret effects on MHD convective flow of second grade fluid through an absorbent medium with ramped wall temperature as well as ramped surface concentration

In the present paper, the heat generating and/or absorption as well as thermo-diffusion on the unsteady free convection MHD gyrating flow of radiation and chemical reactive second grade fluid past an unbounded perpendicular plate during absorbent medium have been discussed. Here, it is assumed that, the confining plate has the ramped wall temperature with ramped surface concentration and isothermal temperature with ramped surface concentration. The analytical solutions for the governing equations are found by utilization of Laplace transformation methodology. The velocity, temperature and concentration profiles are analyzed with quite few figures. It is determined that, velocity, temperature and concentration distribution sketches in case of ramped temperature as well as ramped surface concentration are not as much of as those of isothermal temperature as well as ramped surface concentration. In addition to the idioms of skin friction, Nusselt number as well as Sherwood number are achieved and characterized numerically with tabular format.     

Interactions and uses of antisense peptides in affinity technology.

Antisense peptides, amino acid sequences encoded in the antisense strand of DNA, can interact with significant affinity and selectivity with their corresponding sensepeptides. Experimentally, sense-antisense peptide recognition has been observed repeatedly. However, skepticism about the biological relevance of this phenomenon has persisted. This is due in part to the unexpected and somewhat couterintutive nature of the interaction as well as to its non-universality as an empirical observation. Nonetheless, antisense peptides in several cases investigated so far have been used as immobilized ligands for the successful affinity chromatographic separation of native (sense) peptides and proteins. For example, immobilized antisense peptides corresponding to Arg8-vasopressin (AVP) have been used to separate vasopressin from oxytocin chromatographically as well as to affinity capture AVP-receptor complex. These results, together with improved understanding of the general features of amino acid sequence which drive antisense-sense peptide interactions as well as new ideas for making antisense peptides chimeras, are beginning to suggest improved ways to make antisense-related peptides as affinity agents for separation as well as for other biotechnology applications.     

Oxazole and Isoxazole Chemistry in Crop Protection

An overview is given of the significance of the oxazole and isoxazole scaffolds in crop protection chemistry. The main herbicidally, fungicidally, and insecticidally active oxazole and isoxazole classes are presented, together with their synthesis routes, modes of action, and biological efficacies. In addition, the role of oxazoles and isoxazoles as lead structure or as intermediate in the synthesis of other agrochemicals is reported. Also, partially and fully saturated oxazole and isoxazole derivatives such as oxazolines, isoxazolines, oxazolidines, and isoxazolidines, oxygenated derivatives such as oxazolones and isoxazolones as well as annulated derivatives, such as benzoxazoles and benzisoxazoles, are covered.     

Combining enabling techniques in organic synthesis: continuous flow processes with heterogenized catalysts

The concepts article describes enabling techniques (solid-phase assisted synthesis, new reactor design, microwave irradiation and new solvents) in organic chemistry and emphasizes the combination of several of them for creating new synthetic technology platforms. Particular focus is put on the combination of immobilized catalysts as well as biocatalysts with continuous flow processes. In this context, the PASSflow continuous flow technique fulfils both chemical as well as chemical engineering requirements. It combines reactor design with optimized, monolithic solid phases as well as reversible immobilization techniques for performing small as well as large scale synthesis with heterogenized catalysts under continuous flow conditions.     

Size-exclusion chromatographic behavior of bovine serum albumin in uni-uni valent ions solutions

Summary Molecular interaction between uni-uni valent ions and bovine serum albumin was investigated by size-exclusion chromatography. Elution profiles are first presented for salt and protein solutions as samples with water as the mobile phase; then for water and protein as samples with salt solutions as the mobile phase. The results suggest the existence of a dynamic equilibrium between the salt ions and the protein ions as reactants and the ion-pair (salt-protein) complex as a product.     

香豆素-3-羧酸分子印迹聚合物复合膜对底物的结合及渗透选择性质的研究

在光照和引发剂的作用下, 模板分子香豆素-3-羧酸、 功能单体丙烯酰胺和交联剂乙二醇二甲基丙烯酸酯(EDMA)或三甲氧基丙烷三甲基丙烯酸(TRIM)在聚偏氟乙烯(PVDF)微孔滤膜表面聚合形成分子印迹聚合物复合膜. 用高效液相色谱仪测定了分别以TRIM和EDMA为交联剂制备的分子印迹聚合物膜在不同溶剂中对混合底物的结合和渗透选择性. 结果表明, 以TRIM为交联剂的印迹膜对模板分子具有更高的结合和渗透选择性. 另外, 以乙腈或乙腈/水作为溶剂对分子印迹膜所作的实验和讨论有助于为从复杂样品中分离模板分子奠定理论和实验基础.     

Spectroscopy and photophysics of methylphenylsiloxaneand diphenylsiloxane-based molecules and polymers

Spectroscopy and photophysics of various types of methylphenylsiloxane- and diphenylsiloxane-based oligomers and polymers are reviewed. The molecules treated here include homopolymers such as poly(methylphenylsiloxane) and copolymers such as poly(dimethylsiloxane-codiphenylsiloxane) as well as related oligomers or molecules such as diphenyltetramethyldisiloxane. These polymers and oligomers normally exhibit monomer fluorescence in fluid solution at temperatures near room temperature, and the monomer fluorescence and phosphorescence in rigid matrices at 77 K. In addition to these emissions, the excimer fluorescence is often observed depending on the molecular structure of the siloxanes. These emission properties are rationalized based on the molecular structure and kinetics of the excimer formation processes as well as on the flexibility of the Si-O-Si bonds.     

Green Colorants Based on Energetic Azole Borates

The investigation of green‐burning boron‐based compounds as colorants in pyrotechnic formulations as alternative for barium nitrate, which is a hazard to health and to the environment, is reported. Metal‐free and nitrogen‐rich dihydrobis(5‐aminotetrazolyl)borate salts and dihydrobis(1,3,4‐triazolyl)borate salts have been synthesized and characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and vibrational spectroscopy. Their thermal and energetic properties have been determined as well. Several pyrotechnic compositions using selected azolyl borate salts as green colorants were investigated. Formulations with ammonium dinitramide and ammonium nitrate as oxidizers and boron and magnesium as fuels were tested. The burn time, dominant wavelength, spectral purity, luminous intensity, and luminous efficiency as well as the thermal and energetic properties of these compositions were measured.     

Aptamers: molecular tools for analytical applications

Aptamers are artificial nucleic acid ligands, specifically generated against certain targets, such as amino acids, drugs, proteins or other molecules. In nature they exist as a nucleic acid based genetic regulatory element called a riboswitch. For generation of artificial ligands, they are isolated from combinatorial libraries of synthetic nucleic acid by exponential enrichment, via an in vitro iterative process of adsorption, recovery and reamplification known as systematic evolution of ligands by exponential enrichment (SELEX). Thanks to their unique characteristics and chemical structure, aptamers offer themselves as ideal candidates for use in analytical devices and techniques. Recent progress in the aptamer selection and incorporation of aptamers into molecular beacon structures will ensure the application of aptamers for functional and quantitative proteomics and high-throughput screening for drug discovery, as well as in various analytical applications. The properties of aptamers as well as recent developments in improved, time-efficient methods for their selection and stabilization are outlined. The use of these powerful molecular tools for analysis and the advantages they offer over existing affinity biocomponents are discussed. Finally the evolving use of aptamers in specific analytical applications such as chromatography, ELISA-type assays, biosensors and affinity PCR as well as current avenues of research and future perspectives conclude this review.     

Sugar sensing with synthetic multifunctional pores

Recently, synthetic multifunctional pores have been identified as "universal" detectors of chemical reactions. In this report, we show that with the assistance of enzymes as variable co-sensors, synthetic multifunctional pores can serve as similar universal sensors of variable components in mixed analytes. Sugar sensing in soft drinks is used to exemplify this new concept. This is achieved using invertase and hexokinase as co-sensors and a new synthetic multifunctional pore capable of discriminating between ATP and ADP in an "on-off" manner as sensor. The on-off discrimination between ATP as good and ADP as poor pore blocker is shown to be reasonably tolerant of changing experimental conditions. These results identify universal sensing with synthetic multifunctional pores as a robust, sensitive, and noninvasive method with appreciable promise for practical applications.