Mechanochemical Coupling of Kinesin Studied with a Neck-Linker Swing Model

A neck-linker swing model has been proposed in this work to investigate the mechanochemical coupling of kinesin. The difference between force-velocity curves given by force clamp and fixed trap respectively has been satisfactorily interpreted by this model. The study implies that ADP releasing and ATP hydrolysis are much less forcedependent in force clamp experiments than that in fixed trap experiments in the regime of moderate loading force, which might be a consequence of the delayed response of servo system in force clamp experiments.     

一维链状氢键型甘氨酸超分子化合物[(Gly)2+ (18-crown-6)2(MnCl4)2‒]的合成、 结构及介电性质

以甘氨酸(Gly)、 18-冠醚-6、 二氯化锰(MnCl₂)和盐酸为原料, 通过蒸发法获得一种新型相变一维链状氢键型甘氨酸超分子化合物[(Gly)₂⁺ (18-crown-6)₂(MnCl₄)^2?](1). 通过元素分析、 变温X射线单晶衍射和介电测试等手段对其进行了表征和解析. 实验结果表明, 该晶体属于单斜晶系, 空间群从P2₁/c(100 K)转化为C2/c(293 K). 随着温度升高, [MnCl₄]^2?呈现无序状态的共棱双四面体结构. 质子化甘氨酸分子和分子内羟基(—OH)发生动态摆动, 引起O—H…Cl型一维氢键链产生明显伸缩运动, 导致化合物1在一定温度范围内出现结构相变及介电异常.     

Parametric Study of a Pressure Swing Adsorption Process

The performance of a pressure swing adsorption (PSA) process for production of high purity hydrogen from a binary methane-hydrogen mixture is simulated using a detailed, adiabatic PSA model. An activated carbon is used for selective adsorption of methane over hydrogen. The effects of various independent process variables (feed gas pressure and composition, purge gas pressure and quantity, configuration of process steps) on the key dependent process variables (hydrogen recovery at high purity, hydrogen production capacity) are evaluated. It is demonstrated that many different combinations of PSA process steps, their operating conditions, and the feed gas conditions can be chosen to produce an identical product gas with different hydrogen recovery and productivity.     

Kinetic Separation of Oxygen and Argon Using Molecular Sieve Carbon

A pressure-swing adsorption (PSA) simulation study was performed for the separation of a mixture of 95% O₂ and 5% Ar using a molecular sieve carbon (MSC) as the adsorbent. Two PSA cycles have been outlined to maximize the recovery of either argon or oxygen as a high purity product. The effect of cycle parameters such as cocurrent depressurization pressure, purge/feed ratio, pressure ratio and adsorption pressure on the separation of O₂/Ar has been studied. It was found that it is feasible to obtain an argon product of purity in excess of 80% with reasonably high recovery using one of the cycles. The other cycle is capable of producing high purity oxygen (>99%) at high recovery (>50%) with reasonably high product throughputs. The PSA process can be conducted at room temperature and hence has an advantage over conventional processes like cryogenic distillation and cryogenic adsorption.     

Effect of acoustic field on CO2 desorption in a fluidized bed of fine activated carbon

Adsorption using solid sorbents has the potential to complement or replace current absorption technology, because of its low energy requirements. Among the commercially available adsorbent materials, attention is focused on activated carbons because they are easily regenerable by reason of their low heat of adsorption. These sorbents are generally available in the form of fine powders. Sound-assisted fluidization can process large amounts of fine powders, promoting and enhancing CO₂ capture on fine sorbents, because it maximizes gas–solid contact. Temperature swing adsorption (TSA), consisting of inducing sorbent regeneration and CO₂ recovery by appropriate temperature increase and gas purge, is one of the most promising techniques. This study investigates the CO₂ desorption process by TSA in a sound-assisted fluidized bed of fine activated carbon. Desorption tests were performed under ordinary and sound-assisted fluidization conditions to assess the capability of sound to promote and enhance the desorption efficiency in terms of CO₂ recovery, CO₂ purity, and desorption time. The results show that the application of sound results in higher desorption rates, CO₂ recovery and purity. Regular and stable desorption profiles can be obtained under sound-assisted fluidization conditions. This stability makes it possible to successfully realize a cyclic adsorption/desorption process.     

关于传统扭摆法测物体转动惯量实验的改进

本文针对传统扭摆法测物体转动惯量系统误差较大的缺点,在扭摆的改进和实验数据的处理方面提出了行之有效的方法,从而达到减小系统误差的目的。     

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为充分利用SUNIST球形托卡马克欧姆场的双向磁通,延长等离子体电流平顶时间,对欧姆场的电源系统进行了改造。提出了一种基于多个IGBT并联大电流低频开关的H桥双向放电电路,研发了该双向放电电路的核心元件——3kV/10kA级的IGBT并联大电流开关。对单相电容准恒流充电电路与三相桥式电容换流充电回路进行了研究,合理地确定了双向放电主回路中两组储能电容器C1和C2的充电系统。经过安装、调试以及初步试验,在欧姆场线圈中得到了从正10kA到负6kA的双向放电电流,等离子体电流波形也有明显改善。     

The effects of source/drain and gate overlap on the performance of carbon nanotube field effect transistors

At nanometer regime, fabricating the structures with non-overlapped channel and abrupt doping profile is very complicated and sometimes impossible. So, the resultant device experiences some non-ideal effects which have to be predicted and well addressed by simulation before fabrication. In this paper the effects of overlap between gate and source/drain regions on the performance of carbon nanotube field effect transistors have been investigated. The overlapped structure has been simulated with various doping profiles at drain/source and gate region junction tip. The device performance has been investigated in terms of ON current, Off current, ON/Off current ratio, subthreshold swing, delay, and power delay product (PDP). Simulations show that depending on the variations in the effective channel length, the overlap deteriorates some device characteristics and enhances the others. Where the effective channel length decreases (increases), the overlap deteriorates (enhances) the current ratio and subthreshold swing but enhances (deteriorates) the delay and PDP compared to non-overlapped structure. Furthermore, the overlapped structure with graded profile results in lower current ratio and higher subthreshold swing compared to overlapped structure with abrupt profile. At a fixed current ratio, the delay and PDP of overlapped structure with graded profile are more than overlapped structure with abrupt profile but at a fixed channel length, both profiles have approximately equal delay and PDP.     

Vergleich bekannter Verfahren zur logarithmischen Impulsdichtemessung

Nach Erläuterung des Begriffes logarithmische Impulsdichtemessung werden die Kenngroβen der Integrierschaltungen mit logarithmischer Charakteristik wie logarithmischer Fehler, Bereich, Auflösungszeil und statistischer Fehler beschrieben. Der Hauptteil der Ausführungen befaβt sich mit der Beschreibung der Realisierungsmöglichkeiten für die logarithmische Impulsdichtemessung unter Berücksichtigung wesentlicher Besonderheiten und ökonomischer Gesichtspunkte der einzelnen Varianten. Tabellarisch zusammengestellte Meβwerte gestatten einen Vergleich der verschiedenen Verfahren.     

High CO2‐Capture Ability of a Porous Organic Polymer Bifunctionalized with Carboxy and Triazole Groups

A new porous organic polymer, SNU‐C1 , incorporating two different CO₂‐attracting groups, namely, carboxy and triazole groups, has been synthesized. By activating SNU‐C1 with two different methods, vacuum drying and supercritical‐CO₂ treatment, the guest‐free phases, SNU‐C1‐va and SNU‐C1‐sca , respectively, were obtained. Brunauer–Emmett–Teller (BET) surface areas of SNU‐C1‐va and SNU‐C1‐sca are 595 and 830 m²g^?1, respectively, as estimated by the N₂‐adsorption isotherms at 77 K. At 298 K and 1 atm, SNU‐C1‐va and SNU‐C1‐sca show high CO₂ uptakes, 2.31 mmol g^?1 and 3.14 mmol g^?1, respectively, the high level being due to the presence of abundant polar groups (carboxy and triazole) exposed on the pore surfaces. Five separation parameters for flue gas and landfill gas in vacuum‐swing adsorption were calculated from single‐component gas‐sorption isotherms by using the ideal adsorbed solution theory (IAST). The data reveal excellent CO₂‐separation abilities of SNU‐C1‐va and SNU‐C1‐sca , namely high CO₂‐uptake capacity, high selectivity, and high regenerability. The gas‐cycling experiments for the materials and the water‐treated samples, experiments that involved treating the samples with a CO₂‐N₂ gas mixture (15:85, v/v) followed by a pure N₂ purge, further verified the high regenerability and water stability. The results suggest that these materials have great potential applications in CO₂ separation.