A new method is presented for the calculation of octanol/water partition coefficients. On the basis of summation of atomic contributions, our algorithm, namely; XLOGP, also incorporate correction factors into the calculation. Multivariate regression analysis was performed on a training database of 1831 organic compounds with diverse structures to give the final model. The correlation coefficients for the whole set fitting is 0.968 and the standard deviation is 0.37. The result shows that our model is accurate enough for logP estimation in QSAR studies. Compared to other similar approaches, our method gives better results and is more convenient to use.
塑性有机固体的1H MAS NMR谱通常由一高分辨谱与一宽城谱组成，其中高分辨谱分量对应于塑性相，而宽线谱分量对应于刚性相.长延迟回波-MAS NMR实验可测得塑性相的高分辨谱，CRAMPS方法可测得整个固体1H体系的高分辨谱，常温下它往往以刚性相的贡献为主要成分.实验结果表明，结合1H MAS、回波-MAS与CRAMPS等三种固态高分辨1H NMR技术可望成为深入研究塑性有机固体中塑性相与刚性相的比例，分子结构及运动状态的有效方法.
考察了多体效应（用Stutton－Chen势，SC）对胶体聚团的影响并与双体（Lennard－Jones，LJ）势下的结果作了比较. 研究表明，SC和LJ势下簇团的性质有其相似的一面，如: 随着剪应力的增加，系统里颗粒的平均势能增加，而每个簇团的颗粒数减少；在较强的剪应力场里，簇团沿剪应力方向（X轴）被明显拉长且其主轴偏离X轴等. 但它们间的差异也是明显的，在剪应力下SC系统内颗粒排列得更合理，从而使得平均位能比LJ系统低约1－3个对比能量单位，因而簇团较致密，分形维数较高；颗粒的平均位能，平均簇团大小和分形维数对剪应力的依赖均比LJ系统减弱.在某些条件下簇团的形貌特征也发生了一定程度的改变.
A chemical kinetic method based on the kinetic expression of the second-order reaction on fractals is used to determine the spectral dimension of fractal surfaces. The method can conveniently give the spectral dimension by analyzing the relation between reactant concentration and reaction time (ct～t). The spectral dimension of the Diffusion-Limited Aggregate (DLA) is obtained by Monte Carlo simulation of the desorption process of chemisorbed hydrogen from DLA, and it is in agreement, with that in literature. Also, the spectral dimension of a real catalyst 12% Ni/Al2O3 is obtained by the method.
The colloids of Eu(DBM)3 and ultrafine particles Eu(DBM)3 were perpared. The particle sizes determined by X-ray and by TEM measurements were in 7-30nm range. Their UV absorption and fluorescence spectra were compared with each other and with those of the solid sample. It was shown that the 5D1→7 F1,2 transition was observed in the colloids of Eu(DBM)3 at room temperature. The increase of the excited-state S1 and T1 energy, the peak positions of UV absorption shifted to shorter wavelength, the changes of the absoprtion coefficient with decreasing size were observed.
It was found that the catalyst aged under microwave radiation is much more active for H2O2 decomposition than that aged under conventional heating. Characterization of the catalysts showed that the above result could be interpreted by a hypothesis that orientation of ions (Co2+, Fe3+) in the solution was restricted by microwave electromagnetic field so that the surface of the catalyst is irregular.
A thermometric method in which the heat of reaction is used as a quantitative measure of terminal OH groups in polymers has been in routine use. We use DDIE to determine the terminal OH groups in polyglycol and telechelic polybutadienes by the acetylation reaction of perchloric acid with acetic anhydride. The result is in good agreement with that of chemical titration, thus showing high reliability of DDIE in polymer end-group determination. The method takes less than 5 minutes to carry out. The advantages of DDIE are simplicity, speed and also a repeatability is good.
The heat output of the plant cells-Chlorella vulgaris has been determined using the LKB-2277 bioactivity monitor. The metabolic thermokinetic equation is dP/t = k0, k0 = 0 The experimental results indicate that there is a linear relationship between the meatbolic power and the cell concentration and that the heat output produced by a single cell's metabolism depends on the cell concentration and is inhibited by the increase of the cell density. It presents a special kind of space effect.
The heat production of Wistar rat polymorphonuclear leukocytes (PMN) was measured by an LKB 2277 Thermal Activity Monitor. When PMN were activited with phorbol-12-myristate13-acetate (PMA), the respiratory burst was recorded by greatly incr eased heat production. Experiment was also carred out in the present of the inhibitor, Total Flavonoids of Lycium Barbarum L. (TFL). The respiratory burst heat production peak was disappeared, but the heat production curve was higher than that of PMA because TFL increased the metabolic activities of PMN.
Uniform colloidal particles of BaCO3 are produced in the system of n-octanol, BaCl2 and Na2CO3 aqueous solutions under the action of hexadecyltrimethyammonium bromide(CTAB) by the methods of single-emulsion, double-emulsion, solution and gas-blasting. The key factors, which determine the size, shape and uniformity of the particles, as well as the suitable methods to prepare uniform colloidal particles are figured out by comparing different (water-oil) phase ratios, kinetics of particles' growth and different methods of preparing hydrophobic sols.
The catalyst for dehydrogenation of diethylbenzene(DEB) to divinylbenzene(DVB) was studied. Potassium-promoted iron oxide catalyst was mainly used for ethylbenzene dehydrogenation. If potassium alkli or salt was used directly as promoter, it was noted that the loss of potassium component from the surface of the catalysts pellet result in deactivation. When potassium promoter was added as kaliophilite(KAlSiO4). It was shown that the latter way of adding potassium promoter not only keeps the depression of carbonaceous deposits but also controls the loss of potassium component(the value of loss of potassium component has been reduced three times) , thus making the catalyst having a higher dehydrogention activity.
p-dimethylaminobenzonitrile (DMABN), a typical dual fluorescent flurophore (TICT flurophore), was used as fluorescent probe. The microenviromental property of twelve methyl modified β-cyclodextrin(methyl β-CD) was compared with that of β-cyclodextrin (β-CD). Results showed that the polarity of the cavity of methyl β-CD is lower than that of β- CD, and the capacity of methyl β-CD inclusion with DMABN is stronger than that of β-CD inclusion with DMABN.
Fe2(MoO4)3 ultrafine particle catalyst has been prepared successfully by the sol-gel process at lower temperature. The influences of preparation conditions and thermal treatment conditions on the morphology and structure of the ultrafine particle catalyst has been studied by using TEM, DTA-TG, FT-IR, XRD and BET surface area measurement methods. It is shown that the BET surface area of Fe2(MoO4)3 ultrafine particle prepared by sol-gel method is much larger than that of Fe2(MoO4)3 prepared by coprecipitation method. For the preparation of the well-distribuated Fe2(MoO4)3 ultrafine particles with the size in the range of 40-80nm, the optimum conditions are : treatment temperature <=673K, L/M (Citric acid/Metallic ions)=0.3 and pH<1.0.
The pendent drop or standing bubble method is applied to measure the interfacial tensions between water and nonpolar fluids (n-hexane, n-heptane, nitrogen, oxygen and methane) up to 473K and 220MPa. The high pressure autoclave with t wo visual windows and the auxiliary equipment are described. The sizes(ca 2mm) and shapes of drops or bubbles are recorded with microscope and video camera. The use of digital image permits fast, precise determination of the contour parameters. The densit y values of the liquids or gases have been chosen from literature. A special program is proposed to calculate the interfacial tensions automatically from drop shape at given temperature and pressure. The interfacial tensions σ12 increase with pr essure for the two liquid-liquid systems, but decrease with pressure for the three gas-liquid systems.
In this paper, a set of ATP sensitive K+ channel openers (KCO), whose structure are different, were investigated with the aim to develope our previously defined KCO's pharmacophore model. To validate the effectiveness of the pharmacophore model, A comparative molecule field analysis (CoMFA) was proceeded, aligning the molecules according to the requirernent of the model, and good results were obtained. This pharmacophore model may be a start point to design new KCO compounds.
通过77－298K范围内氢在AX-21活性炭上的吸附数据，探讨如何用普通I-型等温线模型处理超临界条件下的吸附等温线，以获取关于超临界吸附系统的正确信息. 结果表明，Langmuir方程虽然可用来表达实验数据，但不能提供关于该吸附系统的任何可靠信息；Virial方程虽不是整组数据的最好模型，但却能够可靠地确定Henry定律常数，然后可从vant Hoff标绘决定等量吸附热. 通过将实验数据拟合到Dubinin－Astakhov方程，讨论了某些吸附机理.虽然该方程可以最好地表达实验数据，但由于其中的四个参数在回归过程中存在不同程度的相互作用，以及方程中某些物理量在超临界领域定义的不严密性，从D-A方程求出的任何物理量的真实性仍需做进一步探讨.
利用角分辨的飞行时间法研究了355nm脉冲激光烧蚀Ta2O5的反应.由四极质谱测得的烧蚀产物除了O,Ta，Tao和TaO2中性碎片外，在较高激光能量密度时还有O+，Ta+，TaO+，TaO2+离子碎片. 它们的飞行时间（TOF）谱可以用多组分带质心速度的Maxwell-Bolztmann分布函数较好地拟合，原生离子碎片的平均动能与激光能量密度无关.烧蚀产物中原生离子和中性粒子的角分布可以分别用αcosnθ（n≈26）和αcosθ＋bcosnθ（n≈27）函数拟合. 此外，对紫外脉冲激光烧触Ta2O5的机理进行了讨论.
Based on the diffusion action of gallium in silicon and SiO2 ,a diffusion model of gallium doping in bare silicon system and SiO_2/Si system is first presented in this paper ,the gallium doping effect in the two systems is analyzed theoretically. Experiments and applications have proved that the use of the open-tube gallium deffusion in SiO2/Si system can substantially improve diffusion quality and device characteristics .
The copolymerization of CO with ethylene was studied with high pressure in situ IR technique using (DPPPr)Pd(p-CH3PhSO3)2 as the catalyst precursor. Two IR absorptions of carbonyl groups were observed at 1900cm-1 and 1810cm-1 under pure CO ambience, which proved that CO was coordinated with Pd(Ⅱ) under pure CO ambience. Three IR absorptions were observed at 1638, 1616, 1970cm -1 under real reaction conditions, which could be assigned to three intermediates (1,2,3) respectively, indicating that the insertion of CO into Pd-OR bond was probabaly one of the main initation path ways in alcohol solvent.
Nickel-palladium film on p-Si prepared by potential -controlled electrodeposition has much better adherence than that deposited by other methods .To reveal the reasons of this effect, X-ray photoelectron spectroscopy (XPS) combined with Ar+ sputtering was used to investigate the interface of NiPd /Si. The results showed that dramatic interdiffusion of Ni, Pd and Si had occurred at atmospheric temperature. On the XPS spectra of nickel and palladium , there are two kinds of binding energy , contributed by pure metals and metal silicide respectively. NiSi, PdSi and Pd2Si were formed at the interface. Both of the electric field on the surface and the H atoms in the metal lattice have the possibility to promote reactions between nickel or palladium and silicon .
Study of the phase chemistry relation of quaternary system CsBr-SmBr3-(13%)HBr-H2O at 25 ℃ is carried out in order to investigate the reaction of CsBr and SmBr3 in hydrobromic acid. A new compound 5CsBr.2SmBr3.22H2O is discovered and obtained in the system. X-ray powder diffraction, thermal analysis (TG and DTA) and polarization character of the new compound obtained from the system are investigated. Meanwhile, the synthetic mechanisms of compounds (CsSm2Br7, Cs3Sm2Br9, Cs3SmBr6 and Cs2SmBr5) are suggested on the basis of phase chemical relation of the system.
Fluorescein ethyl ester as a model and four dyads of Fluorescein and Anthroic acid linked with different length spacer were synthesized and characterized. They were put in bilayer membrane and on SnO2 coated substrate, The photoinduced voltaic responses were observed and compared when fluorescein was excited using visible light. It was found that the dyads have higher responses than the model, and the dyad with a butylene spacer (n=4) has the highest response. The results and related mechanisms were discussed.
The stability of different crude oil emulsions from ASP flooding production well is studied by the method of a stirred tank. The demulsifying of crude-oil emulsion by different demulsifying agents is discussed. The breakage of the crude oil emulsions from the well PO11 by the different types and concentrations of the emulsifying agents is also discussed. The breaking mechanism of the demulsifying agent is described microscopically.
The influence of adsorbed CO diffusion on the first order phase transition point (y2)of CO oxidation based on Langmuir-Hinshelwood mechanism was studied in detail by Monte Carlo simulation. It was found that CO diffusion increased the value of the first order phase transition point(y2) and when the ratio(k) of diffusion probability of adsorbed CO to adsorption probability of CO is 100, y2 is equal to 0.642. The correlated y2 value is in good agreement with the theoretical result(0.65) obtained by Mai when k approaches to infinity large.
The kinetic processes of the photoionization and dissociation of 4H-furan have been investigated by using synchrontron radiation. The IP of 4H-furan and APs of other ions are gotten from the spectra, the possible channels of dissociative photoionization have been annalyzed. A serices of stable clusters composed of (THF)n. (H2O)n-2H+ (n=2,3,4,5) are present in the MS and the possible structures of the clusters are given.
A photoacoustic detection system consisted of a piezoelectric cylindrical tube transducer is applied to measure the photolysis of Coenzyme B12 (5'-deoxyadenosylcobalamin, AdoCbl) in methanol to obtain the quantum yield, Ф. The value of 0.20±0.05 is in agreement with that obtained in aqueous solution by other authors with an optical method.
A Series of LiCl/γ-Al2O3 samples were prepared by mixing and then heating at 400℃ for 30 hours. 7Li MAS NMR was used to investigated their structures. The 7Li MAS NMR signal of LiCl in the dispersion phase was observed for the first time, and its chemical shift was at 0.25ppm. After the dispersion threshold of LiCl on γ-Al2O3 was achieved, the 7Li signal in the crystalline phase LiCl appears at -1.01ppm and its intensity increases with the increasing in LiCl loading. From the 2D nutation NMR spectra, it can be seen that the electric field gradient surrounding the lithium nuclei in the dispersion state is larger and so the quadrupole interaction is stonger than that in the crystalline state. The dispersion threshold indicated by NMR is in agreement with that deduced from XRD, which is about 0.136gLiCl/gγ-Al2O3.