Glass open-tubular capillary columns with chemically bonded methyl-phenyl siloxane stationary phases of tailor made polarity

Summary The previously described method yielding apolar, chemically bonded methyl polysiloxane glass capillary columns was extended to the production of capillary systems of controlled polarity. The approach involved prior synthesis of a reactive methyl-phenyl polysiloxane polymer by copolymerisation of a mixture of dimethyl and diphenyl chlorosilanes. The polymer was then chemically bonded to the capillary glass surface to yield remarkably stable, high resolution analytical systems which were shown to be particularly well suited to the separation of biochemical mixtures at the subnanogram level. The principle of copolymerisation of differently substituted silanes confers to the method a considerable flexibility which could be used to devise polar capillary systems tailor made for a given analytical problem.     

A comparative investigation of the fatty acid compositions of the seeds of a number of lines of a genetic collection of Gossypium hirsutum

A comparative analysis has been made of the amounts of lipids and their fatty-acid compositions in the seeds of the lines of agenetic collection of cotton plants of the speciesGossypium hirsutum and their hybrids and the variety Tashkent-1. The results obtained on the fatty-acid compositions of some hybrids make it possible to recommend the use of individual lines of cotton plants as donors for improving the food-value indices of cottonseed oil.Institute of Chemsitry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 173–176, March–April, 1991.     

Synthesis,characterization and biological activity of some 1,2,4‐triazine derivatives

4‐Amino‐6‐methyl‐3‐(2H)‐thioxo‐5‐(4H)‐oxo‐1,2,4‐triazine ( 1 ) was condensed with 2‐methyl (or phenyl)‐4H‐3,1‐benzoxazin‐4‐one ( 5a,b ) in boiling acetic acid to give compounds 8‐11 . Reacting 1 with chloroacetyl chloride afforded the corresponding chloroacetamido and triazinothiadiazine derivatives 12 and 13 . Condensing 2 with succinic anhydride and/or phthalic anhydride yielded compounds 14 and 15 . Benzoylation of 4‐amino‐6‐methyl‐3‐(2H)‐thioxo‐5‐(4H)‐oxo‐2‐(2,3,4,5‐tetra‐O‐acetyl‐α‐D‐glucopyra‐nosyl)‐1,2,4‐triazine ( 19 ) afforded the corresponding 4‐N,N‐dibenzoyl derivative 20 . Deblocking of the N‐2 glycoside 21 and the S‐glycoside 22 by methanolic ammonia gave compounds 23 and 24 . Acetylation of 4‐amino glycoside 25a afforded the corresponding 4‐mono‐ and 4‐diacetyl derivatives 26 and 27 . Deamination of 25a,b yielded compounds 28a,b . Methylation of compound 28b afforded the corresponding N4‐ and S‐methyl derivatives 29 and 30 .     

Offline estimation of 2D crystal lattice parameters by processing the electron diffraction image

Electron diffraction provides useful information about the internal composition of materials and has been in the use of material scientists for more than fifty years. In order to extract useful information from offline diffraction images, they are manually analyzed by using some photometric technique. Manual analysis is however a cumbersome, laborious and difficult task. To reduce the labors of material scientists one can employ image processing techniques to perform automated analysis, due to the well established popularity and clear evidence of widely used image processing techniques. In this work an image processing technique is being proposed for the extraction of 2D unit cell information from diffraction images on one hand and finding the 2D point group contained by the lattices on the other. The technique employs a morphological shrinking operation to find the center of each spot in the underlying preprocessed diffraction image. This is followed by the extraction of eight points with reference to the spot produced by the transmitted electron beam. The resultant nine points, i.e. the extracted eight plus the reference spot generated by the transmitted electron beam, are then subjected to symmetry operations, rotation symmetry and mirror symmetry, in polar coordinate system, to classify the point group of the lattice produced by the electron diffraction. One of the difficult task, even in manual analysis, is to ascertain the exact spot where the transmitted electron beam hit the sample at the time of realization of the image. This has been accurately and intuitively done by employing the notion that the transmitted spot must have greater number of pixels, with the highest gray value, among the diffracted spots. The proposed strategy has been applied to a sample set of various images and the results shows that the technique is efficient in determining the unit cell in 2D and classify the point group with good accuracy.     

Synthesis,Crystal Structure,and Conductivity Investigation of a New Monophosphate: (2-CH3OC6H4CH2NH 3)H2PO4

Chemical preparation, crystal structure, thermogravimetric and differential analysis, solid state ³¹P MAS NMR characterization, and IR spectroscopic investigations are given for a new organic cation dihydrogenmonophosphate, (2-CH₃OC₆H₄CH₂NH₃)H₂PO₄. This compound is monoclinic C2/c, with unit cell parameters a = 27.740(8), b = 4.827(2), c = 16.435(3) Å, β = 93.79(2)°, V = 2196 (1) ų, Z = 8, and ρ = 1.422 g · cm^?3. The crystal structure has been determined and refined to R = 0.046 (Rw = 0.056), using 1,746 independent reflections with I > 3σ (I). Its atomic arrangement can be described by infinite polyanions [H₂PO₄] _n ^{n ?}, organized in ribbons alternating with organic cations. Strong hydrogen bonds connect the different components. Electrical conductivity measurements show that the [2-CH₃OC₆H₄CH₂NH₃]H₂PO₄ has a low ionic conductivity value at 403 K.     

Ultra-lightweight paper foams: processing and properties

A methodology for producing a low density cellulose-based foam has been developed by combining a surfactant with pulp, mixing at high velocity to entrain air, and then drying in a non-restrained fashion. The structure of the foam, characterized through optical microscopy and X-ray computed tomographic microscopy, consists of pulp fibres in random orientations surrounding air bubbles along with large void spaces. Through careful design of experiments, the effect of fibre type, length distribution, surfactant, and air content on the mechanical behavior and permeability of the foam material was investigated. The results indicate that foamed cellulose materials can be produced at a strength of one-half the tensile strength of a standard handsheet, but having a relative density of only one percent. No chemical additives were used to enhance the strength of these samples as the properties of the foam material are enhanced simply through variation of the process parameters. Thus, a strong cellulose-based foam, with a density as low as 10 mg/cm³, can be fabricated using standard papermaking infrastructure and hence at low cost.     

Nickel Supported on Alkaline Earth Metal–Doped γ-Al2O3–La2O3 as Catalysts for Dry Reforming of Methane

Russian Journal of Applied Chemistry - Nickel catalysts supported on γ–Al2O3 doped with La2O3 and alkaline earth oxides (MgO, CaO, and SrO) were investigated in the dry reforming of...     

Microchemical surface analysis of two Numidian coins

This work is a contribution to the microchemical surface analysis of two Numidian coins. Numidia was an ancient kingdom of northern Algeria during 2nd and 1st century BC. Investigations were performed with scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS), energy dispersive X-ray fluorescence spectrometry (EDXRF) and X-ray diffraction (XRD). The identification of the coins was done thanks to the name initials and effigy of King Massinissa. SEM observations of coins showed heterogeneous surfaces. SEM and EDXRF analyses showed an alloy structure with copper (65%), antimony (19%) and lead (16%). The XRD identified a metal structure and corrosion products which were on the coin surfaces: Litharge (PbO), Hydrocerussite (Pb₃(CO₃)₂(OH)₂), Bindheimite (Pb₂Sb₂O₇) and Bystromite (MgSb₂O₆).     

多功能两亲梳状聚合物的合成及包覆荧光量子点

利用溶液聚合和成酰胺反应合成了多功能梳状两亲性共聚物,聚(甲基丙烯酸-co-甲基丙烯酸十八酯)-(乙醇胺-乙二胺叶酸)(PSM-EE-FA).用红外光谱(FTIR),核磁共振(1H-NMR)及凝胶渗透色谱(GPC)表征了该聚合物的结构及分子量分布.实验结果证明合成了该聚合物,其数均分子量(Mn)为28600,多分散性为1.375.用该两亲梳状聚合物包覆油溶性CdSe/ZnS量子点,通过相转移作用,得到水溶性靶向量子点(PSM-EE-FA-QDs).该水溶性量子点溶液具有较好的稳定性.通过紫外-可见(UV-Vis)及荧光发射光谱分析对该量子点的光学性质进行研究.结果表明,PSM-EE-FA-QDs的紫外-可见光谱及荧光发射光谱峰形与原量子点基本一致.由于量子点表面聚合物层的形成,峰位发生少量红移.该量子点水溶液的荧光强度是原量子点氯仿溶液的98%,荧光产率是原量子点氯仿溶液的95%.动态光散射(DLS)及透射电镜(TEM)测试结果表明水溶性量子点分布均匀.合成的水溶性量子点不但光学性能稳定,而且聚合物及水溶性量子点的合成方法较为简便.     

相对论性核碰撞中Φ介子产生和弦碎裂函数

用强子和弦级联模型LUCIAE系统研究从AGS到SPS,到RHIC,再到LHC能量核–核碰撞中Φ介子产生.采用与能量有关弦碎裂函数,并通过与荷电粒子多重数实验数据的比较确定其中的参数后,LUCIAE模型给出的Φ介子产额与实验数据也都相近,得到的事件平均弦碎裂变量随能量之增趋饱和规律,可能是核穿透性能量行为的定性表示.