Phonon Dispersion in Equiatomic Li-Based Binary Alloys

The computations of the phonon dispersion curves （PDC） of four equiatomic Li-based binary alloys, namely Li0.5Na0.5, Li0.5K0.5, Li0.5Rb0.5 and Li0.5Cs0.5, to second order in the local model potential is discussed in terms of the real-space sum of Born von Karman central force constants. Instead of the concentration average of the force constants of metallic Li, Na, K, Rb and Cs, the pseudo-alloy atom （PAA） is adopted to compute directly the force constants of four equiatomic Li-based binary alloys. The exchange and correlation functions due to Hartree （H） and Ichimaru-Utsumi （IU） are used to investigate the influence of screening effects. The phonon frequencies of four equiatomic Li-based binary alloys in the longitudinal branch are more sensitive to the exchange and correlation effects in comparison with the transverse branches. However, the frequencies in the longitudinal branch are suppressed due to IU-screening function than the frequencies due to static H-screening function.     

Plain and ion-pair thin-layer chromatography of synthetic dyes on an admixture of silica gel G and barium sulfate in an aqueous ethanol system

An easy, inexpensive, and accurate method for the analysis of synthetic dyes by means of ion-pair thin-layer chromatography (IPTLC) on mixed sorbent phases containing silica gel G and barium sulfate in an aqueous ethanol system is studied. The effect of the composition of the sorbent phases has a major effect on the hundred-fold relative migration rate, as also does the effect of the ion-pairing reagent as the impregnant. Compact and sharp spot application yields very good binary and ternary separations and enables their clear identification. IPTLC has better separations on mixed sorbent phases, which are not possible on plain mixed phases in thin-layer chromatography. The method can be applied for the trace analysis of synthetic dyes in various natural and synthetic samples.     

Neoclassical tearing physics in the spherical tokamak MAST

Results from MAST provide a first test of neoclassical tearing mode physics in the spherical tokamak (ST). The mode accounts for the main performance limit in conventional tokamaks. Its behavior in the ST is remarkably well described by existing theoretical models, although it is more readily seeded by sawtooth events in these scenarios. Modeling confirms the significance of stabilizing field-curvature effects. This provides good grounds for optimism that with suitable control of profiles, it may be possible to avoid these modes in the ST.     

柱芯电极光谱法测定西藏斑岩铜矿中的铜,钼,银,铅,锌,砷,钨和铋

本文研究了柱芯电极测定西藏斑岩铜矿中8个主次要元素,并与用其他电极测定的结果进行了对比实验。本文还讨论了组分影响及消除方法。对铜矿区样品测定,其RSD(n=15)为Cu±3.3%,Mo±4.1%,Ag±3.7%,Pb±6.5%。Zn±6.5%,As±7.3%,W±6.9%以及Bi±6.9%。用化学分析,外检和标样验证了方法的可靠性。     

Thermodynamics of 1,10-phenanthrolium ion in ethanol—water

Dissociation constants of the 1,10-phenanthrolium ion in different aqueous ethanolic solutions have been determined spectrophotometrically and pH-metrically. Some aspects of the role of the solvent have been discussed.     

Rapid and localized electron internal-transport-barrier formation during shear inversion in fully noninductive TCV discharges

Clear evidence is reported for the first time of a rapid localized reduction of core electron energy diffusivity during the formation of an electron internal-transport barrier. The transition occurs rapidly (approximately = 3 ms), during a slow (approximately = 200 ms) self-inductive evolution of the magnetic shear. This crucial observation, and the correlation of the transition with the time and location of the magnetic shear reversal, lend support to models attributing the reduced transport to the local properties of a zero-shear region, in contrast to models predicting a gradual reduction due to a weak or negative shear.     

Experimental study of trapped-electron-mode properties in tokamaks: threshold and stabilization by collisions

Trapped electron modes are one of the candidates to explain turbulence driven electron heat transport observed in tokamaks. This instability has two characteristics: a threshold in normalized gradient and stabilization by collisions. Experiments using modulated electron cyclotron heating in the ASDEX Upgrade tokamak demonstrate explicitly the existence of the threshold. The stabilization with increasing collisionality is evidenced by a strong decrease of the propagation of heat pulses, explained by a transition to ion temperature gradient driven transport. These results are supported by linear gyrokinetic calculations.     

Particle pinch with fully noninductive lower hybrid current drive in Tore Supra

Recently, plasmas exceeding 4 min have been obtained with lower hybrid current drive (LHCD) in Tore Supra. These LHCD plasmas extend for over 80 times the resistive current diffusion time with zero loop voltage. Under such unique conditions the neoclassical particle pinch driven by the toroidal electric field vanishes. Nevertheless, the density profile remains peaked for more than 4 min. For the first time, the existence of an inward particle pinch in steady-state plasma without toroidal electric field, much larger than the value predicted by the collisional neoclassical theory, is experimentally demonstrated.     

Superconducting state parameters of Cu C Zr100−C metallic glasses

The theoretical investigation of the superconducting state parameters (SSP) viz. electron-phonon coupling strength λ, Coulomb pseudopotential μ*, transition temperature T _c, isotope effect exponent α and effective interaction strength N ₀ V of ten Cu _C Zr_100?C metallic glasses have been reported using Ashcroft’s empty core (EMC) model potential. Three local field correction functions proposed by Hartree (H), Taylor (T) and Ichimaru-Utsumi (IU) are used in the current investigation to study the screening influence on the aforesaid properties. It is observed that the electron-phonon coupling strength λ and the transition temperature T _C are quite sensitive to the selection of the local field correction functions, whereas the Coulomb pseudopotential μ*, isotope effect exponent α and effective interaction strength N ₀ V show weak dependences on local field correction functions. The T _c obtained from IU-local field correction function are found an excellent agreement with available theoretical or experimental data. Also, the present results are found in qualitative agreement with other such earlier reported data, which confirms the superconducting phase in metallic glasses.