Instability of the melt flow in VGF growth with a traveling magnetic field

The linear instability of a thermally stratified melt flow in the VGF configuration driven by a traveling magnetic field (TMF) is considered numerically and experimentally. The dependency of the instability threshold on the governing parameters is found for several cuts through the parameter space covering a wide range of possible applications. In a first approximation the linear instability occurs when the dimensionless TMF forcing parameter reaches the magnitude of the Grashof number. This is particularly true in a medium-sized crucible where the first instability is axisymmetric and sub-critical. As the Grashof number increases the flow develops self-similar boundary layers and the instability becomes three-dimensional. The instability originates in the bottom boundary layer where the convection tends to suppress the imposed temperature gradient in the central part of the melt zone. It is shown that the TMF may serve as a tool to control the phase interface shape without causing flow instationarity when the crucible diameter exceeds a certain value. This value is estimated to be around 6 cm for GaAs. The flow stays stable if the TMF is used for a reversal of the meridional flow with the aim to remove a possible dopant concentration peak on the axis.     

Manipulating Electric Double Layer Adsorption for Stable Solid-Electrolyte Interphase in 2.3 Ah Zn-Pouch Cells

Constructing a reliable solid-electrolyte interphase (SEI) is imperative for enabling highly reversible zinc metal (Zn⁰) electrodes. Contrary to conventional “bulk solvation” mechanism, we found the SEI structure is dominated by electric double layer (EDL) adsorption. We manipulate the EDL adsorption and Zn²⁺ solvation with ether additives (i.e. 15-crown-5, 12-crown-4, and triglyme). The 12-crown-4 with medium adsorption on EDL leads to a layer-structured SEI with inner inorganic ZnF_x/ZnS_x and outer organic C−O−C components. This structure endows SEI with high rigidness and strong toughness enabling the 100 cm² Zn||Zn pouch cell to exhibit a cumulative capacity of 4250 mAh cm⁻² at areal-capacity of 10 mAh cm⁻². More importantly, a 2.3 Ah Zn||Zn_0.25V₂O₅⋅n H₂O pouch cell delivers a recorded energy density of 104 Wh L_cell⁻¹ and runs for >70 days under the harsh conditions of low negative/positive electrode ratio (2.2 : 1), lean electrolyte (8 g Ah⁻¹), and high-areal-capacity (≈13 mAh cm⁻²).     

Gene transfer and protein release of fission yeast by application of a high voltage electric pulse

A high voltage electric pulse can be applied to induce the uptake of DNA into cells and the release of protein from cells. In transformation procedures, electroporation is widely used since the technique is simple, rapid, reproducible, and highly efficient. In extraction of protein, on the other hand, electroextraction has many advantages over other conventional extractions. We have developed a highly efficient method for the electroporation of fission yeast. In particular, application of a high voltage electric pulse to fission yeast improves the cellular uptake and release of macromolecules controlled by both osmotic conditions and electric field strength.

Spectral measurements of inductively coupled and helicon discharge modes of a laboratory argon plasma source

An experimental study was conducted to investigate the effects of several operational parameters in the emission spectra, in the 400-850 nm wavelength region, of a laboratory Argon plasma source. In particular, the emission spectra of the inductively coupled plasma and the Helicon plasma modes of operation were compared. Comparisons of spectra point to a significant increase in the ionization fraction of the plasma for the Helicon mode of operation. The spectral measurements allow one to determine the major trends in the plasma electron density for various parameters such as power delivered to the helical antenna, propellant mass flow rate, and applied external magnetic field intensity.Analysis of a prominent Argon single ion line, at 434.8 nm, points out that the plasma electron density increases linearly with the power delivered to the helical antenna, and that there is an optimum propellant mass flow rate for maximum ionization fraction. Additional analysis of the same line shows that above a minimum applied axial magnetic field intensity, the variation in the magnetic field strength has little effect on the plasma electron density.     

交流阻抗法在细胞分析中应用的研究进展

交流阻抗法作为一种新型的无标记、全程动态、实时分析方法已在细胞研究中得到了广泛应用。本文综述了基于交流阻抗法进行细胞分析的研究新进展,重点对非法拉第阻抗谱法和法拉第阻抗谱法用于细胞分析的原理及应用进行了总结,主要包括交流阻抗法在细胞形态、细胞生长、细胞增殖、细胞凋亡以及作用于细胞的药效和毒性研究中的应用,并对其发展趋势进行了展望。     

两例具有大磁滞的氰根桥联{FeⅢ2NiⅡ}单链磁体

我们利用具有不同对称性的同分异构体,通过改变分子间氢键网络,操控单链磁体行为,成功合成了2例化合物：[Ni^Ⅱ（L1）][Fe^Ⅲ（Tp）（CN）₃]₂·3.5H₂O （1）和[Ni^Ⅱ（L2）][Fe^Ⅲ（Tp）（CN）₃]₂·3H₂O （2）,其中Tp=hydrotris （pyrazolyl） borate,L1=3,4-bis （1H-imid-azol-1-yl） thiophen,L2=1,2-bis （1H-imidazol-1-yl） thiophen）。磁性研究表明,1和2表现为具有不同矫顽场的单链磁体行为。1的矫顽场为8.41 kOe,而2的矫顽场为3.84 kOe。