Clathrate formation in water-cyclic ether systems at high pressures

Experimental data on the investigation of the water-trimethyleneoxide system,P, t, x phase diagram (up to 6 kbar) are presented. The results are compared with those on water systems with ethyleneoxide, 1,3- and 1,4-dioxane, 1,3-dioxolane and tetrahydrofuran, on the basis of which a summarizedP, t, x diagram is plotted for water-cyclic ether systems. It is shown that in all the systems in which a cubic structure II hydrate forms at 1 bar, it eventually turns to cubic structure I under pressure. The nature of high pressure hydrates is discussed.Dedicated to the memory of D. W. Davidson.     

WS2 超细粉体的固相法合成

WS2 超细粉体的固相法合成;WS2;固相反应;过硫系数;高能球磨;粒度     

Characterization of some essential oils and their key components: Thermoanalytical techniques

The present study was aimed at determining the kinetics of evaporation and establishing vapor pressure curves for both single and multi-component systems by thermogravimetry (TG) and differential scanning calorimetry (DSC). Essential oils (e.g. lavender oil, orange oil, clove oil and eucalyptus oil, etc.) are typically multi-component systems consisting of various volatile pure components (e.g. linalyl acetate, limonene, cinnamaldehyde, etc.) which resemble single component systems. In this study linalyl acetate was taken as the calibration compound for TG. The vapor pressure curves for the pure substances were plotted using TG and vapor pressure plots for clove oil and eucalyptus oil were constructed using DSC. The thermodynamic and kinetic parameters of the pure compounds were compared to that of the multi-component systems to quantitatively and qualitatively measure the influence of different compounds on each other. The k-value from the vapor pressure data for linalyl acetate was calculated as 112006 Pa kg^0.5mol^0.5s^-1 m^-2 K^-0.5. The vapor pressure values were used to determine the Antoine constants using the SPSS 10.0 software.This revised version was published online in November 2005 with corrections to the Cover Date.     

群青颜料呈色机理的电子顺磁共振研究

研究了阿富汗青金石矿石、敦煌石窟青金石颜料、合成群青的呈色机理。实验表明三者均有ｇ＝２．０２９峰，前两者多一个ｇ＝２．０４７峰，４００℃时，ｇ＝２．０４７峰变平，６００℃时消失。ｇ＝２．０２９峰随温度升高而增强，８００℃时增强放慢，颜色也随温度变深。在Ｍ０Ｏ３／ＳｉＯ２和Ｍ０Ｏ３／Ａｌ２Ｏ３表面上，Ｓ２＾－的ＥＰＲ有ｇ１＝２．０４７，ｇ２＝２．２０８，ｇ３＝１．９９８三个分量。因此，群青、青金石和     

XPS,AFM, ATR and TPD evidence for terraced,dihydrogen terminated, 1×1 (100) silicon

Heating (100) silicon at high temperature (say, higher than 850 °C) in H₂, cooling to 670–700 °C in the same ambient, and quenching to room temperature in N₂ results in environmentally robust, terraced 1 × 1 (100) SiH₂. Evidence for this conclusion is based on angle‐resolved x‐ray photoelectron spectroscopy, atomic force microscopy, infrared absorption spectroscopy in the attenuated total reflection mode, thermal programmed desorption, and reflection high‐energy electron diffraction. Copyright © 2005 John Wiley & Sons, Ltd.     

Development of a new analytical method for the evaluation of hazards from slow decomposition of waste streams and process solutions

A wide variety of liquid streams are generated as part of the process research and development effort. Frequently these streams are drummed off, either as intermediates that must be held for processing or as wastes that must be sent off-site for disposal. Because of the long times and low concentrations often involved, current thermoanalytical techniques were inadequate to detect the potential of streams to generate gas. A custom-made apparatus, the gas evolution test cell (GETC), was developed in the Merck Research Laboratories to measure the gas generation potential of various streams under precisely defined conditions, is the key innovation for the development of a quantitative gas-generation test method.     

Thermal decomposition of struvite

Struvite (NH₄MgPO₄·6H₂O) is a mineral often found in urinary tracts and kidneys. Thermal decomposition using slow low heating shows that the 'kidney' stone can be decomposed at temperatures below 40°C. At this temperature both ammonia and water are evolved. If more rapid heating is employed the decomposition occurs at around 80°C. The implication of this work rests with the use of low slow heat for the decomposition of the kidney stones. This revised version was published online in July 2006 with corrections to the Cover Date.     

pH,Definition and measurement at high temperatures

In this review paper, the NBS scale and its limitations are briefly discussed. The magnitude of liquid junction potentials and some calculated values are presented. The use of a molality scale for hydrogen electrode concentration cells at high temperatures is described, and results from measurements on ionization equilibria are summarized. Use of this scale is also recommended for certain circumstances with cells without liquid junction. As an alternative activity scale, use of the Pitzer ion-interaction treatment for ions is recommended for special cases. Finally, reference data are presented for _±HCl in HCl(aq) to 350°C and (HCl+NaCl)(aq) to 200°C that were derived by use of the Pitzer ion-interaction treatment.Presented at the Second International Symposium on Chemistry in High Temperature Water, Provo, UT, August 1991.     

Magnetic phase transitions in nanostructures induced by shear stress under high pressure

Magnetic phase transitions of the first and second order were revealed by Mössbauer spectroscopy in nanosystems of - and -ferric oxides and metallic europium subjected to shear stress (240°) under high pressure (20 kbar). For - and -ferric oxide nanoclusters, the Curie (Neel) points decreased to 300 K, whereas for nanostructured europium the Neel point increased from 90 to 100 K. The thermodynamic model of magnetic phase transitions predicting a change in the character of magnetic phase transitions and a decrease (increase) in the critical Neel (Curie) points in nanoclusters was developed. The type of magnetic phase transitions and the change in the critical points were caused by defects in nanoclusters, whose maximum concentration was observed for the clusters with the 20—50 nm size range.     

人血清中地尔硫高效液相色谱法测定及药代动力学参数

建立了反相高效液相色谱法监测人口服地尔硫艹卓缓释片后血药浓度。血样用正己烷－氯仿－异丙醇混合溶剂（６０４０５）提取后，以Ｃ１８化学键合硅胶为固定相，甲醇－水－三乙胺为流动相，安定为内标，在２３９ｎｍ波长处定量检测。血药浓度在１５～３００μｇ／Ｌ范围内线性关系良好，最低检测浓度为３μｇ／Ｌ。批内（ｎ＝７）及批间（ｎ＝５）测定相对标准偏差分别小于６．８％和８．４％，回收率为９１％～１０４％。监测了８名健康人口服盐酸地尔硫艹卓缓释片后的不同时间的血药浓度变化，计算了有关的药代动力学参数。