Xe偶－偶同位素低激发态性质的IBM2描述

通过考虑同类核子相干对Ｓρ、Ｄρ间的四极相互作用，在ＩＢＭＺ中对Ｘｅ偶一偶同位素１１６Ｘｅ—１３２Ｘｅ的低激发态能谱和Ｅ２跃过几率进行了理论分析．计算结果有效地改善了ＩＢＭ中这些核的准γ带能谱的Ｓｔａａｓｅｒｉｎｇ现象，较精确地描述了实验观察到的低激发态的性质．     

The overload phenomenon in gas chromatography

The usual concepts of the dynamics of an overloaded solute band fail to explain several phenomena such as the typical “leading-tail” shape and retention deviations exhibited by overloaded peaks, and why these defects are more commonly observed in short columns. These and other related deviations from theory can be rationalized by a non-classical approach to the overloading phenomenon.     

The Dirichlet-Jordan test and multidimensional extensions

If is a foliation of an open set by smooth -dimensional surfaces, we define a class of functions , supported in , that are, roughly speaking, smooth along and of bounded variation transverse to . We investigate geometrical conditions on that imply results on pointwise Fourier inversion for these functions. We also note similar results for functions on spheres, on compact 2-dimensional manifolds, and on the 3-dimensional torus. These results are multidimensional analogues of the classical Dirichlet-Jordan test of pointwise convergence of Fourier series in one variable.

     

(2+1)维非对称 Nizhnik-Novikov-Veselov系统的新映射解及其局域结构

映射法是一种非常经典、有效和成熟的求解非线性演化方程的方法，其最大的特点是可以有多种不同形式的设解，使得最终求得的解丰富多彩. 利用改进的 Riccati 方程映射法和变量分离法，得到了(2+1)维非对称 Nizhnik-Novikov-Veselov 系统的新显式精确解.根据得到的孤波解，构造出该系统的峰孤子和分形孤子等局域结构，研究了两个孤立波的“追碰”现象. 关键词： 改进的映射法 (2+1)维非对称 Nizhnik-Novikov-Veselov 系统 局域结构 “追碰”现象     

Direct analysis of anabolic steroids in urine using Leidenfrost phenomenon assisted thermal desorption-dielectric barrier discharge ionization mass spectrometry

Rapid detection of trace level anabolic steroids in urine is highly desirable to monitor the consumption of performance enhancing anabolic steroids by athletes. The present article describes a novel strategy for identifying the trace anabolic steroids in urine using Leidenfrost phenomenon assisted thermal desorption (LPTD) coupled to dielectric barrier discharge (DBD) ionization mass spectrometry. Using this method the steroid molecules are enriched within a liquid droplet during the thermal desorption process and desorbed all-together at the last moment of droplet evaporation in a short time domain. The desorbed molecules were ionized using a dielectric barrier discharge ion-source in front of the mass spectrometer inlet at open atmosphere. This process facilitates the sensitivity enhancement with several orders of magnitude compared to the thermal desorption at a lower temperature. The limits of detection (LODs) of various steroid molecules were found to be in the range of 0.05–0.1 ng mL⁻¹ for standard solutions and around two orders of magnitude higher for synthetic urine samples. The detection limits of urinary anabolic steroids could be lowered by using a simple and rapid dichloromethane extraction technique. The analytical figures of merit of this technique were evaluated at open atmosphere using suitable internal standards. The technique is simple and rapid for high sensitivity and high throughput screening of anabolic steroids in urine.     

酸性AlCl3-BMIC离子液体中的铝阳极溶解

采用线性扫描伏安法研究了Lewis 酸性AlCl₃-BMIC (BMIC: 1-butyl-3-methylimidazolium chloride)离子液体中铝电极的溶解. 铝电极在阳极极化时出现了钝化现象, 钝化是由于在铝电极表面形成了固体AlCl₃钝化膜造成的. 铝的电化学溶解过程可以依次分为三个区: 电化学控制区、过渡区和钝化区. 在电化学控制区, 铝的电化学溶解速率随着电位的正移而逐渐增加; 在过渡区, 由于电极表面AlCl₄^-和Al₂Cl₇^-浓度发生改变而析出固体AlCl₃使得铝电化学溶解速率随着电位的正移而逐渐减小; 当钝化膜形成之后, 铝的电化学溶解速率不再随着电位的正移而发生改变, 铝溶解进入钝化区. 增加搅拌、升高温度、降低离子液体AlCl₃摩尔分数都可以增加铝溶解阳极极限电流密度.     

聚丙烯酰胺水溶液的流变性质

粘性指进现象;聚丙烯酰胺水溶液的流变性质     

Phenomenological and neural-network modeling of cephalosporin C production bioprocess

Cephalosporin C production process withCephalosporium acremonium ATCC 48272 in synthetic medium was investigated and the experimental results allowed the development of a mathematical model describing the process behavior. The model was able to explain fairly well the diauxic phenomenon, higher growth rate during the glucose-consumption phase, and the production occurring only in the sucrose-consumption phase. Moreover, the process was simulated utilizing the neural-networks technique. Two feed-forward neural-networks with one hidden layer were employed. Both models, phenomenological and neural-networks based, satisfactorily describe the bioprocess. The difficulties in determining kinetic parameters are avoided when neural networks are utilized.     

电化学刻蚀法制备LaB6场发射微尖锥阵列

采用电化学刻蚀方法,成功制备出单尖的六硼化镧、钼、钨及钨铼合金场发射冷阴极尖锥,并对这几种场发射单尖锥阴极的电子发射性能进行了测试比较.结果表明,LaB₆作为场发射阴极,具有良好的发射性能和稳定性.在〈111〉面单晶LaB₆基片上,用PECVD法沉积非晶硅作掩膜,制备出具有一定高度的LaB₆微尖锥场发射阵列,结果发现,LaB₆基底较为平整,尖锥阵列呈现出各向异性.该结论对LaB₆材料在场发射阴极方面的进一步研究具有重要的指导意义.     

Swelling of poly(N-isopropylacrylamide) gels in water-aprotic solvent mixtures

The swelling volume of poly(N-isopropylacrylamide) (PIPAAm) gel in aprotic solvents (acetonitrile (AcN)-, tetrahydrofuran (THF)-, 1,4-dioxane (DO)- and dimethylsulfoxide (DMSO))-water mixtures was measured at 25°C. The gel swollen in water shrank first and then reswelled with addition of the aprotic solvents. At an intermediate mole fraction (XDMSO) range of DMSO-water mixtures, the gel demonstrated a reentrant swelling phenomenon the hydrated gel shrank first on addition of a small amount of solvent, showed a typical wide reentrant transition, and gradually reswelled in the range near pure solvent. On the other hand, the gels in AcN-, THF-, and DO-water mixtures demonstrated a reentrant-convex swelling phenomenon: the gels reswelled after a reentrant phase transition in low Xorg (XAcN, XTHF and XDO), showed a maximum swelling in the intermediate Xorg region, and shrank again gradually in the high Xorg region. Such a swelling behavior of the gel was interpreted by correlating with solution properties of the aqueous aprotic solvent mixtures.The strength of hydrogen bonding around amide groups of the homopolymer was examined in pure solvents (water, THF, and DMSO) and in all proportion of aqueous THF to observe the relation with swelling behavior of gel by spectrum analysis of the amide I and II bands of Fourier Transform Infrared Spectroscopy (FT-IR). The swelling properties of gels in solvents and the aqueous mixtures were well correlated with the peak shifts of amide groups of the homopolymer.