Critical current degradation behaviors of ReBCO coated conductor tapes under pressurized liquid nitrogen

In the case of 2G coated conductor (CC) tapes, it has been reported that thin–thick CC tapes with IBAD substrate showed a superior electromechanical property even at smaller bending radius compared with the cases of 1G BSCCO tapes. Considering the application of CC tapes it is significant to evaluate the transport property under operating environment, because CC tapes might experience a change in operating pressure that can affect its current carrying capacity due to temperature variation and deformation. This study was focused on the I_c degradation behavior in bent CC tapes under pressurized liquid nitrogen. Differently processed YBCO and SmBCO CC tapes with IBAD substrate are used as samples. The bending strain characteristics at elevated pressure levels were evaluated by using the ρ-shaped sample holder which can induce different bending strain values at pressured state. Depressurization and thermal cycling were performed to check the reversibility of I_c in CC tapes. Vacuuming tests were also carried out to investigate the characteristics of I_c at different LN₂ temperature levels.     

Learning Electricity with NIELS: Thinking with Electrons and Thinking in Levels

Electricity is regarded as one of the most challenging topics for students of all ages. Several researchers have suggested that na?ve misconceptions about electricity stem from a deep incommensurability (Slotta and Chi 2006; Chi 2005) or incompatibility (Chi et al. 1994) between na?ve and expert knowledge structures. In this paper we argue that adopting an emergent levels-based perspective as proposed by Wilensky and Resnick (1999), allows us to reconceive commonly noted misconceptions in electricity as behavioral evidences of “slippage between levels,” i.e., these misconceptions appear when otherwise productive knowledge elements are sometimes activated inappropriately due to certain macro-level phenomenological cues only. We then introduce NIELS (NetLogo Investigations In Electromagnetism), a curriculum of emergent multi-agent-based computational models. NIELS models represent phenomena such as electric current and resistance as emergent from simple, body-syntonic interactions between electrons and other charges in a circuit. We discuss results from a pilot implementation of NIELS in an undergraduate physics course, that highlight the ability of an emergent levels-based approach to provide students with a deep, expert-like understanding of the relevant phenomena by bootstrapping, rather than discarding their existing repertoire of intuitive knowledge.

Preparative isolation of hydrolysable tannins chebulagic acid and chebulinic acid from Terminalia chebula by high-speed counter-current chromatography

As a chromatographic column, the high-speed counter-current chromatography system was equipped with a preparative HPLC series, enabling the successful isolation of hydrolysable tannins from the fruits of Terminalia chebula, a traditional Chinese medicine. The two-phase solvent system was composed of n-hexane-ethyl acetate-methanol-water (1:20:1:20 v/v). As a result, 33.2 mg chebulagic and 15.8 mg chebulinic acids were obtained in one step from 300 mg of crude extract. Their purities were determined by HPLC to be 95.3 and 96.1%, respectively. The chemical structures were identified by their MS and 1H NMR spectra.     

A four-electrode microconstant direct current resistance detector for ion chromatography applying ion-exchange membrane and porous electrode

A four-electrode microconstant direct current resistance detector for ion chromatography not sensitive to the effects of electrode polarization, capacitance, and electrolysis by-products is proposed. A constant current of microampere magnitude is applied across the current electrodes of the four-electrode device, and the voltage responses between the detection probes are directly picked up by a high input impedance instrumentation amplifier. The ion-exchange membranes, which separate the detection chamber from the electrolysis chambers, enable the measurement of solution resistance free of the interference of electrolysis by-products. Two resin beds in the detection chamber serve as ion conductors while reduce the dead volume of the detector. Recycled detection effluent supplies water for the electrolysis reactions at the current electrodes to sustain constant current in solution. The porous detection probes provide microchannel for the flowing solution while indicating signals. Owing to the constant current excitation, the electronics setup becomes simple. The cell configuration, operating principle, electronics, and error analysis of this detection mode are discussed along with their use for suppressed anion chromatography. Experimental data show that this four-electrode direct current detection mode is comparable to conventional two-electrode alternating current method.     

Josephson tunneling in bilayer quantum Hall system

A Bose–Einstein condensation is formed by composite bosons in the quantum Hall state. A composite boson carries the fundamental charge (−e  ). We investigate Josephson tunneling of such charges in the bilayer quantum Hall system at the total filling ν=1$\nu =1$. We show the existence of the critical current for the tunneling current to be coherent and dissipationless. Our results explain recent experiments due to [L. Tiemann, Y. Yoon, W. Dietsche, K. von Klitzing, W. Wegscheider, Phys. Rev. B 80 (2009) 165120] and due to [Y. Yoon, L. Tiemann, S. Schmult, W. Dietsche, K. von Klitzing, Phys. Rev. Lett. 104 (2010) 116802]. We predict also how the critical current changes as the sample is tilted in the magnetic field.     

存在自旋轨道耦合的介观小环中的持续自旋流

文章作者研究了存在自旋轨道耦合的介观小环的平衡态性质.此前人们已经知道,在有磁通穿过的介观小环中,绕环运动的电子会产生一附加的Berry相位而导致持续电流;同样地,在仅有自旋轨道耦合的体系中,电子绕环运动也应当会产生附加的自旋Berry相位,进而驱动持续自旋流.文章作者通过对一个有正常区和自旋轨道耦合区的复合小环的计算,结果表明,无电流伴随的纯持续自旋流的确存在.文章作者指出,这持续自旋流描述真实的自旋运动,并且它能被实验观测.     

钨酸盐/过钨酸盐体系阴极间接电氧化合成红曲黄色素

以自制SBS-g-(AA/StSO3Na)/SBS-g-DMAEMA双极膜作电解槽阴阳两极室的隔膜,借助正交试验确定阴极电还原氧气产生过氧化氢的最优条件,进而利用钨酸钠/过钨酸钠体系由阴极间接电氧化红曲红制备红曲黄色素.实验表明:以石墨作电极,阳极液为10%硫酸溶液,阴极液为0.5g·L-1红曲红丙酮水溶液,添加钨酸钠(浓度15mmol/L),调节pH至3,在通氧速率65cm3/min,电流密度5.78mA.cm-2下电解2h,阴极平均电流效率可达72.39%.电解产物经红外表征和紫外跟踪分析,证实了红曲红烯键环氧化反应的发生.     

Anomalous currents in dense matter under a magnetic field

We consider fermionic dense matter under a magnetic field, where fermions couple minimally to gauge fields, and calculate anomalous currents at one loop. We find anomalous currents are spontaneously generated along the magnetic field but fermions only in the lowest Landau level contribute to anomalous currents. We then show that there are no more corrections to the anomalous currents from two or higher loops.