皂甙类药材的显微化学鉴别法

用显微化学方法对十八种皂甙类药材进行鉴别,观察到了明显的显色反应和沉淀反应。说明在排除有类似反应的预处理条件下,用显微化学方法来鉴别皂甙类药材是可行的。这种办法简单易行,可用于野外药材调查。

偏光显微粉末法在秦俑、汉阳陵颜料鉴定中的应用

为探索偏光显微粉末法在颜料鉴定中的应用 ,利用该方法并辅以显微化学法 ,对采自秦俑和汉阳陵等地颜料的晶体颗粒的大小、形状、颜色、表面形态、折射率、双折射率和消光性等光学性质分别进行了测定。结果表明 ,鉴定出秦俑样品中有 10种颜料 ,汉阳陵中有 5种颜料 ,且秦俑的紫色颜料中加入的朱砂与汉阳陵相比颗料较大数量也较多。说明了该方法可鉴别古代无机和有机颜料 ,并可望用于岩石、陶瓷、锈蚀物等方面的分析。

Expression of COX-2, PCNA, Ki-67 and p53 in gastrointestinal stromal tumors and its relationship with histopathological parameters

AIM: To investigate the expression of Cyclooxygenase-2 (COX-2), proliferating cell nuclear antigen (PCNA), Ki-67 and p53 in gastrointestinal stromal tumors (GISTs) and its relationship with histopathological parameters. METHODS: Twenty-five GISTs were examined by light microscopy and immunohistochemistry. c-kit, CD34, SMA, S-100 protein, COX-2, PCNA, Ki-67 and p53 were detected immunohistochemically and the relationship was evaluated among histopathologic parameters such as mitotic index (MI), tumor grade, tumor size, COX-2, PCNA, Ki-67 and p53. RESULTS: COX-2 protein expression was found in 19 of 25 (76%) of the tumors, and expression was noted in the cytoplasm of the tumor cells. p53 was significantly related to MI and tumor grade but no relationship was found between COX-2, proliferation markers and MI, tumor grade and tumor size. CONCLUSION: COX-2 is expressed in most GISTs and it may play an important role in the proliferation and progression of these tumors or a useful marker to identify GIST. Although immunohistochemical assessment of p53 can be used for distinguishing the risk groups of GISTs, tumor size and mitotic rate should be considered at the same time.

Separation of chalcopyrite and pyrite from a copper tailing by ammonium humate

Copper tailings constitute a large proportion of mine wastes. Some of the copper tailings can be recycled to recover valuable minerals. In this paper, a copper tailing was studied through the chemical analysis method, Xray diffraction and scanning electron microscope-energy dispersive spectrum. It turned out that chalcopyrite(Cu) and pyrite(S) were the main recoverable minerals in the tailing. In order to separate chalcopyrite from pyrite in low pulp pH, ammonium humate(AH) was singled out as the effective regulator. The depression mechanism of AH on the flotation of pyrite was proved by FTIR spectrum and XPS spectrum, demonstrating that there was a chemical adsorption between AH and pyrite. By Response Surface Methodology(RSM), the interaction between AH, pulp pH and iso-butyl ethionine(Z200) was discussed. It was illustrated that the optimal dosage of AH was 1678 g·t^(-1) involving both the recovery of Cu and S. The point prediction by RSM and the closed-circuit flotation displayed that the qualified Cu concentrate and S concentrate could be obtained from the copper tailing.The study indicated that AH was a promising pyrite depressor in the low pulp pH from copper tailings.

Layer by layer synthesis of Sn-Co-C microcomposites and their application in lithium ion batteries

Alloy anodes were studied for pursuing Sn-based microcomposite synthesis, assembly and performance for lithium ion batteries. The self-assembled Sn-Co-C composites with nano-scaled microstructures were prepared via solution method and carbothermal technology. The morphology and physical structure were investigated with scanning electron microscope (SEM) and X-ray diffraction (XRD). The as-prepared materials were assembled to half cell coin for the purpose of discussing the galvanostatic cycling, cyclic voltammetry and rate-capability performance. Results reveal that nanoscaled CoSn 2 alloys covered with Sn and C layer by layer are wrapped by cross-linked porous carbon network to form spherical microstructure. This distinguishing feature of Sn-Co-C composites provides a possible solution to the problems of Sn particle aggregation and poor electron transport, and has strong effect on improving electrochemical performance.

Growth process and corrosion resistance of micro-arc oxidation coating on Mg-Zn-Gd magnesium alloys

A Mg-6Zn-3Gd(mass fraction,%) alloy,noted as ZG63,was coated by different micro-arc oxidation(MAO) processes,and the coating structure and corrosion resistance of the alloy were studied using scanning electron microscopy(SEM),glancing angle X-ray diffractometry(GAXRD) and various electrochemical methods.The micro-arc oxidation process consists of three stages and corresponds with different coating structures.In the initial stage,the coating thickness is linearly increased and is controlled by electrochemical polarization.In the second stage,the coating grows mainly inward and accords with parabolic regularity.In the third stage,the loose coating forms and is controlled by local arc light.The looser coating is mainly composed of MgSiO3 and the compact coating is mainly composed of MgO.From micro-arc oxidation stage to local arc light stage,the corrosion resistance of the coated alloy firstly increases and then decreases.The satisfied corrosion resistance corresponds to the coating time ranging from 6 to10 min.

Characteristic evaluation of Al_2O_3/CNTs hybrid materials for micro-electrical discharge machining

The characteristic evaluation of aluminum oxide （A1203）/carbon nanotubes （CNTs） hybrid composites for micro-electrical discharge machining （EDM） was described. Alumina matrix composites reinforced with CNTs were fabricated by a catalytic chemical vapor deposition method. A1203 composites with different CNT concentrations were synthesized. The electrical characteristic of A1203/CNTs composites was examined. These composites were machined by the EDM process according to the various EDM parameters, and the characteristics of machining were analyzed using field emission scanning electron microscope （FESEM）. The electrical conductivity has a increasing tendency as the CNTs content is increased and has a critical point at 5% A1203 （volume fraction）. In the machining accuracy, many tangles of CNT in A1203/CNTs composites cause violent spark. Thus, it causes the poor dimensional accuracy and circularity. The results show that conductivity of the materials and homogeneous distribution of CNTs in the matrix are important factors for micro-EDM of A1203/CNTs hybrid composites.

Preparation of calcium phosphate coatings on Mg-1.0Ca alloy

The calcium phosphate coatings were prepared by virtue of electrochemical deposition in order to improve the corrosion resistance of Mg-1.0Ca alloys in simulated body fluids.The chemical compositions,structures and morphologies of the coatings were investigated by energy dispersive spectroscopy(EDS),X-ray diffractometry(XRD)and scanning electron microscopy(SEM), respectively.The potentiodynamic electrochemical technique was employed to investigate the bio-degradation behavior of Mg-1.0Ca alloys with Ca-P coatings in Hank's solutions.The experimental results show that the deposited coatings predominately consist of flake-shape brushite(DCPD,CaHPO4·2H2O)crystallites.The corrosion resistance of the substrates with coatings is improved in Hank's solutions significantly.

Characterization and Desulfurization Possibilities of High Sulfur Gediz-Turkey Coal

Coal is one of the important energy sources, but it causes serious environmental problems such as air pollution, acid rain and greenhouse effects. Sulfur in coal is one of the responsibilities of these negative effects. Coal includes two types of sulfur： organic and inorganic. While inorganic sulfur can be completely removed with physical desulfurization methods, organic sulfur can be removed only by chemical desulfurization methods. But chemical methods are not only expensive but also difficult processes. Firstly in desulfurization, types of the sulfur content in coal should be well characterized. High sulfur Gediz-Turkey coal has been chosen to this study. This coal basin is located in the centre of the Turkey. In this study, characterization and desulfurization possibilities of high sulfur Gediz coal were investigated. For this purpose, several physical and chemical characterization methods such as proximate and ultimate coal analysis （ash, calorific value, volatile matter, moisture and sulfur analysis）, mineralogical and petrographic analysis, fourier transform infrared spectroscopy, scanning electron microscope were used. Results of these analysis are shown that Gediz coals include 3.15% pyritic sulfur and 2.89% organic sulfur. Removing pyritic sulfur from Gediz-Turkey coal with physical methods such as gravity and sink-float separation is not possible because pyrite particle has 1-2 micron liberation size in coal.

Interaction between Spermatozoa and the Different Epithelia along the Female Reproductive Tract of Mustelus schmitti

The presence of sperm was observed in different organs of the reproductive tract of M. schmitti. These were the club, baffle and terminal zone of the oviducal gland, posterior portion of the uterus and in the cervix. This fact allowed for consideration not only its storage but its interaction with the female reproductive tract epithelia as well. SEM （microscopic observation studies） detected loose and sole spermatozoa in the club and baffle zones in a pregnant female. On the other hand, histochemical techniques showed sperm storage tubules of the terminal zone, which contain bundles of sperm, do not stain AB （alcian blue） or PAS （periodic acid schiff）. Disintegration of some of the male gametes was observed in the posterior part of the uterus with TEM （transmission electron microscopy） studies which would indicate a first uterine sperm selection. The uterine epithelial cells involved in this process showed an important level of secretion vacuoles suggesting an interaction with sperm cells. Sperm in the cervix was found without the matrix that constitutes the spermatozeugmata formed in the male tract. Some heads of the sperm were uncurled while they were interacting with the cervical cells.

Stabilization of Magnetite Nanoparticles by Encapsulation into the Silica Matrix

Different methods have been investigated for the synthesis of magnetic nanoparticles. Control of the particle size, dispersion, purity and stability have been always regarded an issue. In this study magnetite （Fe304） superparamagnetic nanoparticles with a size range about 20 nm have been successfully synthesized using chemical co-precipitation method from the solution of ferrous/ferric mixed salt-solution in alkaline media in oxygen-free environment. The sol-gel method has been chose to encapsulate magnetic nanoparticles into silica matrix. The phase structures, morphologies, surface area, functional classes and magnetic properties have been characterized by X-ray diffraction, SEM and AFM, BET, FT-IR and VSM. The results showed that the resultant films, consisting of encapsulated magnetite have crack free and smooth surface with a roughness value 1.5 rim.

Electrocatalytic Activity of Tungsten Carbide and Natural Zeolite Composite in Aqueous Solution

Tungsten carbide and zeolite nanocomposite was prepared by combining a mechanochemical approach with a reduction and carbonization approach,using natural zeolite and ammonia metatungstate as precursors.The sample was characterized by X-ray diffraction and scanning electron microscope.The results showed that the crystal phase of the sample is composed of zeolite,monotungsten carbide and bitungsten carbide.The mass percentage and the crystallite diameter of tungsten carbide change along with the reacted time.Its electrocatalytic activity was measured with a microelectrode system with three electrodes.The results show that its electrocatalytic property is related to its crystal phase and the mass percentage of tungsten carbide,and its electrocatalytic activity is connected with the property of electrolyte,in which it is measured.Synergistic effect between tungsten carbide and zeolite is found during electrocatalysis.

Stablility and Size Control of Silver Nanoparticles by Electrochemical Method

Silver nanoparticles （Ag-NPs） were prepared using an electrochemical technique. The optical properties were measured by absorption spectroscopy. The dimension of the prepared nanoparticles as estimated by the Atomic Force Microscope （AFM）, was 91.57 nm. This reaserch effort proposes a mechanism for reducing the size of silver nanoparticles by adding the hydrogen peroxide （H202）, and protecting the silver nanoparticle to inhibit agglomeration by adding PVP polymer.

In-situ interaction of nano-PbS with gelatin

Water-soluble gelatin-PbS bionanocomposites （BNCs） were synthesized via a facile one-pot chemical reaction method at pH 7.40. The samples were characterized by transmission electron microscopy （TEM）, X-ray diffraction （XRD）, UV-vis absorption spectra （UV-vis）, Fourier transform infrared spectra （FT-IR） and circular dichroism （CD）. FT-IR data were used to envis- age the binding of PbS particles with oxygen atoms of carbonyl groups of gelatin molecule. The possible integration mechanism between gelatin and PbS was discussed in detail. The effect of Pb2＋ and PbS on the conformations of gelatin has also been analyzed by means of UV-vis, CD and FT-IR spectra, resulting in less c^-helix content and more open structures （[3-sheet, r-turn, or expanded）. A new formula to calculate the association constant was proposed according to the relationship between the absorbance of gelatin-PbS BNCs and the free concentration of PbS, and apparent association constants K （298/303/308 K： 3.11/2.00/1.60 × 10^6 tool/L） at three different temperatures were calculated based on this formula. Thermodynamic parameters such as AG^θ, △Hθ and △S^θ were also determined. The results of the thermodynamic investigations indicated that the reaction was spontaneous （AG^θ 〈 0）, and enthalpy-driven （△H^8 〈 0）.

Nanoelectrochemical architectures for high-spatial-resolution single cell analysis

The analysis of single cells instead of cell populations is important for characterizing cellular heterogeneity and elucidating the cellular signalling pathways. Nanoelectrodes have emerged as an increasingly important tool for biomolecule analyses at the single-cell level with high spatial or temporal resolution. Various electrochemical methods, such as amperometry and scanning electrochemical microscopy(SECM), have been applied. Research to date has focused on the development of new nanoelectrochemical architectures, such as arrays, to achieve higher spatial resolution and faster analysis rates for single-cell analysis. In this review, the fabrication of these new nanoelectrochemical architectures and their applications in high spatial resolution single-cell analyses are discussed. The recent progress of Chinese researchers is highlighted.