Comparative study of Li, Na, and K adsorptions on graphite by using ab initio method

A comprehensive study has been conducted to compare the adsorptions of alkali metals (including Li, Na, and K) on the basal plane of graphite by using molecular orbital theory calculations. All three metal atoms prefer to be adsorbed on the "middle hollow site" above a hexagonal aromatic ring. A novel phenomenon was observed, that is, Na, instead of Li or K, is the weakest among the three types of metal atoms in adsorption. The reason is that the SOMO (single occupied molecular orbital) of the Na atom is exactly at the middle point between the HOMO and the LUMO of the graphite layer in energy level. As a result, the SOMO of Na cannot form a stable interaction with either the HOMO or the LUMO of the graphite. On the other hand, the SOMO of Li and K can form a relatively stable interaction with either the HOMO or the LUMO of graphite. Why Li has a relatively stronger adsorption than K on graphite has also been interpreted on the basis of their molecular-orbital energy levels.     

Model compounds of caged capsaicin: design, synthesis, and photoreactivity

Molecules were prepared with substituted nitrobenzyl groups covalently bonded to N-(4-hydroxy-3-methoxybenzyl)acetamide (2) by ether or carbonate linkages. These compounds decomposed under irradiation at 363 nm. Those with carbonate linkages decomposed at slower rates than those with ether linkages. Molecules with dimethoxy-substituted benzyl groups decomposed more slowly than monomethoxy-substituted benzyl groups due to the electronic characteristics of the benzylic carbon.     

含聚醚间隔链的扩链脲改性环氧树脂/双氰双胺固化体系性能研究

合成了一系列含不同分子量聚环氧丙烷 (PPG)柔性间隔链的扩链脲 ,系统考察了扩链脲改性环氧树脂E 5 1/双氰双胺 (dicy)固化体系的固化反应活性、动态力学行为、冲击性能和断裂面形态结构 ,并对体系的冲击性能、形态结构与动态力学行为之间的关系进行了探讨 .结果表明 ,改性体系固化反应活性明显提高 ,固化反应表观活化能降低 ,固化反应峰顶温度从 190℃降低至 14 0℃ ,固化反应的表观活化能由 14 5 5kJ/mol降至 70～ 80kJ mol;改性体系冲击强度明显提高 ,其中所含PPG柔性链分子量为 10 0 0的扩链脲改性的E 5 1/dicy体系冲击强度较未改性的E 5 1/dicy体系提高了 8倍 ,其冲击试样断裂面的形态具有明显的韧性断裂特征 ,微观两相网络结构的存在导致了改性体系冲击强度显著提高     

Microdialysis sampling coupled to HPLC for transdermal delivery study of ondansetron hydrochloride in rats

The transdermal delivery of ondansetron hydrochloride (ON) solution in propylene glycol (PG) with a widely used penetration enhancer, oleic acid (OA), was studied in rats by a microdialysis sampling technique. Dialysate samples collected from the probe were directly injected into the HPLC system without any pre-treatment and no interference occurred in the blank sample. A good linearity between the standard concentrations and peak areas within the calibration range was achieved. In vivo recovery (32.52 +/- 1.8%) of the probe was assessed with the retrodialysis method, which was used to calculate the ON concentration in the dermis. Oleic acid at the concentrations of 2% and 5% (w/v) increased the steady-state delivery rate from 0.001 to 0.030 and 0.058 microg/h, respectively. OA proved to be an effective enhancer for transdermal delivery of ON in rats.     

Effects of injector geometry and sample matrix on injection and sample loading in integrated capillary electrophoresis devices

The double-T injector design employed in many microchip capillary electrophoresis devices allows for the formation of very small (50-500 pL) sample plugs for subsequent analysis on-chip. In this study, we show that sample plugs formed at the channel junction can be geometrically defined. The channel width and injector symmetry prove to be of great importance to good performance. A unique pushback of solvent into the side channels can be induced when the side channels have a very low resistance to flow, and this helps to better define the injected sample plug. Samples and running buffers of differing ionic strength (e.g., 10 mM KCl buffer and 20 mM KCl sample) can yield widely variable results in terms of plug shape and amount injected (variations of 1.5 to 10x). Applying bias voltages to all the intersecting channels aids in controlling the plug shape. However, when the ionic strengths of buffer and sample are not matched, the actual amount injected (up to 10x variations) can be inconsistent with the appearance of the plug formed in the injector (up to only 30 % variations). Operating at constant pH and ionic strength produced the most consistent results. This report examines the effects of altering the injector geometry and solution ionic strengths, and presents the results of using bias voltages to control plug formation. The observed results should provide a benchmark for modeling of the fluid dynamics in channel intersections.     

硫酸介质中Ti／SnO2／PbO2析氧阳极的研究

由于硫酸溶液具有高的电导、一般条件下性质稳定、价格相对低廉等优点，所以电化学合成大多在硫酸溶液中进行．阳极析氧是电化学合成不可避免的阳极过程．但因硫酸的强腐蚀性，以及从阳极析出的氧的强氧化性，使得能满足工业生产的阳极材料很缺乏．自１９５０年荷兰Ｈｅｎ...     

细胞动力学研究VIII.Na2SeO3对黑根菌作用特征

The Characteristics of the action of Na2SeO3 on Rhizopus nigrocans has been studied by means of microcalorimetry, the relationship between growth rate constants and the concentration of Na2SeO3 is
k=0.03608exp[-0.003608(c+8.60)2]
It was found that Na2SeO3 of low concentration has promoting action on the growth of Rhizopus nigrocans cells, and high concentration of Na2SeO3 has inhibitory action. The study has provided a lot of information on the bioaffect of selenium and the research of toxicology.     

Effect of surface mobility on the particle sliding along a bubble or a solid sphere

The sliding velocity of glass beads on a spherical surface, made either of an air bubble or of a glass sphere held stationary, is measured to investigate the effect of surface mobility on the particle sliding velocity. The sliding process is recorded with a digital camera and analyzed frame by frame. The sliding glass bead was found to accelerate with increasing angular position on the collector's surface. It reaches a maximum velocity at an angular position of about 100 degrees and then, under certain conditions, the glass bead leaves the surface of the collector. The sliding velocity of the glass bead depends strongly on the surface mobility of a bubble, decreasing with decreasing surface mobility. By a mobile surface we mean one which cannot set up resistive forces to an applied stress on the surface. The sliding velocity on a rigid surface, such as a glass sphere, is much lower than that on a mobile bubble surface. The sliding velocity can be described through a modified Stokes equation. A numerical factor in the modified Stokes equation is determined by fitting the experimental data and is found to increase with decreasing surface mobility. Hydrophobic glass beads sliding on a hydrophobic glass sphere were found to stick at the point of impact without sliding if the initial angular position of the impact is less than some specific angle, which is defined as the critical sticking angle. The sticking of the glass beads can be attributed to the capillary contracting force created by the formation of a cavity due to spontaneous receding of the nonwetting liquid from the contact zone. The relationship between the critical sticking angle and the particle size is established based on the Yushchenko [J. Colloid Interface Sci. 96 (1983) 307] analysis.     

与时俱进，不断开创物理化学课程建设新局面

As a necessary basic theory course for undergraduates majoring in chemistry, materials, pharmacy, chemical engineering, and biology, physical chemistry plays an important role in cultivating talents to meet the needs of social and economic development. Over the years, the teaching team of physical chemistry of East China University of Science and Technology has carried out the curriculum reform and innovation persistently based on "Team building as the foundation, resource building as the root, mode innovation as the soul, ability training as the origin". This paper will summarize our thinking and experience in striving for the first-class course from the aspects of first-class team construction, first-class resource construction, teaching connotation innovation, teaching mode exploration, and extract the experience that can be used as reference by teaching peers.     

Untersuchung des Systems Silbertellurid-Silberchlorid

Investigation of the System Silver Telluride—Silver Chloride The system Ag₂Te? AgCl has been investigated by differential-thermal X-ray-phase, and micro-structural analysis within the concentration range from 0 to 100 mole-% silver telluride. Equilibrium samples were obtained by tempering for 480 hours at 330°C. The system silver telluride—silver chloride is of an eutectic type, with an eutectic point corresponding to 80 mole-% AgCl and 377°C. At 510°C and 33 mole-% AgCl, one observes the formation of a compound of a peritectic type with the probable composition Ag₅Te₂Cl.