算术数列中弱合数的分布

把弱合数的分布推广到算术数列中，给出了两个渐近公式。     

The influence of electrodes on the performance of light-emitting electrochemical cells

We demonstrate that the electrochemical properties of the electrode material can have a dramatic impact on the performance of light-emitting electrochemical cells (LECs). Specifically, we report results from planar wide-gap LECs containing a blend of poly(2-methoxy,5-(2′-ethylhexyloxy)-p-phenylene vinylene) (MEH-PPV), poly(ethylene oxide) and LiCF₃SO₃ as the active material. We find that Au electrodes are preferable over Al electrodes, since Au-electrode devices exhibit fast turn-on (i.e., p-n junction formation time) and clearly visible light emission during operation at 5 V and 360 K, while Al-electrode devices exhibit slow turn-on (due to a delayed onset of p-doping progression) and no visible light emission. These results are rationalized with a cyclic voltammetry study, which demonstrates that Al is oxidized at a lower potential than the p-doping (oxidation) potential of MEH-PPV, while Au is electrochemically inert over the entire voltage range spanned by the p- and n-doping potentials of MEH-PPV. Consequently, the oxidation charge injected into Al-electrode devices results in a combination of p-doping of MEH-PPV and formation of Al ions. The latter process is undesired since it results in a slow turn-on time and quenched light emission. Finally, we find that planar LECs in a bottom-electrode configuration exhibit a faster turn-on time than identical devices with the electrodes on top of the active material.     

河道堤防模拟决口水利计算简化法

本文分析了堤防决口泛区水流机理,提出了决口水利计算简化算法的公式及列表试算求解的方法,说明了决口泛区图绘制应注意的问题。     

建筑物密集城区溃堤水流二维数值模拟

通过考虑社区和楼房内部的容水性,引入侵入水量的概念,建立了能够模拟建筑物密集城区溃堤水流运动的数学模型。该模型采用有限体积法对浅水方程进行非结构离散,通过Roe格式计算界面数值通量,给出了侵入水量的合理估算方法。通过物理模型的试验结果验证了本文模型的准确性和稳定性。最后应用该模型对哈尔滨市可能发生的溃堤洪水进行模拟,计算结果表明,该模型能较好地模拟溃堤洪水在城区内的运动过程,侵入系数的变化对计算结果有比较明显的影响。     

电动势测量误差的Taylor级数推导

电位分析法是电化学分析法的一个重要组成部分,在各行各业的应用日趋广泛,因而对它的测量准确度的要求就显得极为重要。本文用Taylor级数对电动势测量误差进行了推导,得出了更精确的计算公式,同时对原计算式的误差问题进行了讨论,加深了学生对电位分析误差的理解。     

促进宋代印刷技术进步的主要因素

在深入研究文献的基础上,探讨了促进宋代印刷技术进步的主要因素:纸业兴盛品质优良,为印刷业提供了优质的承印材料;制墨技艺突飞猛进,为印刷业提供了上乘的转印介质;专业写版群体出现,提高了写版速度与印刷文字的艺术性;刻工家族已然形成,使雕刻技艺得以提高;刷印技术专人承担,进一步提高了印刷质量。     

Progression of the stacked Golgi compartments in the yeast Saccharomyces cerevisiae by overproduction of GDP-mannose transporter

The Golgi compartments of the yeast Saccharomyces cerevisiaeare dispersed within the cytoplasm, in contrast to the stacked cisternae in the mammalian cell, and consequently are observed as a punctate pattern by immunofluorescent staining of Golgi-marker proteins. The VIG4/VRG4 gene encodes the essential yeast GDP-mannose transporter, which is a polytopic membrane protein in the early and medial Golgi compartments. Upon overexpression of this gene by the aid of a strong promoter and multicopy vector, we found that stacked multivesicular structures, which resembled the cisternae of mammalian Golgi apparatus, had developed in S. cerevisiae. Immuno-electron microscopy showed that the GDP-mannose transporter was located on the stacked cisternae. Immuno-isolation and immunoblotting analyses of the vesicles showed that the overproduced GDP-mannose transporter also co-localized with the Golgi glycosyltransferases, but not with the ER- or late Golgi-marker proteins as in the control cell. We propose that the localization mechanism of the GDP-mannose transporter in the Golgi compartment would be efficient and hardly saturable, and therefore the overproduced protein induced a progression of Golgi-like compartments rather than being mislocalized in other compartments, such as the ER or a vacuole.     

Applying a Behavioral Economic Framework to Understanding Adolescent Smoking.

Adolescents' choice to smoke may depend on substitute reinforcers for smoking, complementary activities to smoking, and individual differences in reinforcer value. The influence of these variables on smoking was determined among 983 adolescents. Substitutes were school involvement, academic performance, physical activity, and sports team participation: complements were peer smoking and substance use; delay discounting assessed individual differences in reinforcer value. Latent growth modeling indicated that substitute reinforcers reduced the odds of smoking progression almost two-fold, complementary reinforcers increased the odds by 1.14. and delay discounting indirectly influenced the odds of smoking progression through complementary reinforcers. Adolescents who smoke may have fewer reinforcers that protect against smoking and more reinforcers that promote smoking. Discounting of future rewards affects smoking through reinforcer type. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Failure of nickel-aluminum-bronze hydraulic couplings,with comments on general procedures for failure analysis

Failures of various types of hydraulic couplings used to connect pipes in a naval vessel are described and used to illustrate some of the general procedures for failure analysis. Cracking of couplings, which were manufactured from nickel-aluminum-bronze extruded bar, occurred in both seawater and air environments. Cracks initiated at an unusually wide variety of sites and propagated in either longitudinal or circumferential directions with respect to the axis of the couplings. Fracture surfaces were intergranular and exhibited little or no sign of corrosion (for couplings cracked in air), and there was very limited plasticity. Macroscopic progression markings were observed on fracture surfaces of several couplings but were not generally evident. At very high magnifications, numerous slip lines, progression markings, and striations were observed. In a few cases, where complete separation had occurred in service, small areas of dimpled overload fracture were observed. It was concluded from these observations, and from comparisons of cracks produced in service with cracks produced by laboratory testing under various conditions, that cracking had occurred by fatigue. The primary cause of failure was probably the unanticipated presence of high-frequency stress cycles with very low amplitudes, possibly due to vibration, resonance, or acoustic waves transmitted through the hydraulic fluid. Secondary causes of failure included the presence of high tensile residual stresses in one type of coupling, undue stress concentrations at some of the crack-initiation sites, and overtorquing of some couplings during installation. Recommendations on ways to prevent further failures based on these causes are discussed.