HCN laser scattering on the JIPP T-IIU tokamak

A 4-channel HCN laser scattering system has been developed and applied to the JIPP T-IIU tokamak. Main aim of this system is to study microturbulence excited in the plasma, especially in the high power ICRF heating experiment. The observed density fluctuations are in a frequency range of the electron diamagnetic drift wave and have broad frequency spectra. The main part of the wavenumber is found to satisfy the condition of . In the heating experiments, deterioration of the energy confinement time is observed, and the density fluctuation level increases with the increase of the heating power.     

Excitonic detectors of infrared and submillimeter radiation

The theory of new type detectors based on the quenching of secondary emission in direct-gap semiconductors (lines of Raman light scattering due to interaction between free and bound excitons in the crystal, and also bands of edge radiation) caused by IR or submillimeter radiation is proposed. The results obtained are confirmed by the experiment performed for CdS crystal excited by ultraviolet radiation of mercury lamp, at liquid helium temperature.     

Coherent Phonon-Induced Modulation of Charge Transfer in 2D Hybrid Perovskites

Electron–phonon interactions play an essential role in charge transport and transfer processes in semiconductors. For most structures, tailoring electron–phonon interactions for specific functionality remains elusive. Here, it is shown that, in hybrid perovskites, coherent phonon modes can be used to manipulate charge transfer. In the 2D double perovskite, (AE2T)₂AgBiI₈ (AE2T: 5,5“-diylbis(amino-ethyl)-(2,2”-(2)thiophene)), the valence band maximum derived from the [Ag_0.5Bi_0.5I₄]^2– framework lies in close proximity to the AE2T-derived HOMO level, thereby forming a type-II heterostructure. During transient absorption spectroscopy, pulsed excitation creates sustained coherent phonon modes, which periodically modulate the associated electronic levels. Thus, the energy offset at the organic–inorganic interface also oscillates periodically, providing a unique opportunity for modulation of interfacial charge transfer. Density-functional theory corroborates the mechanism and identifies specific phonon modes as likely drivers of the coherent charge transfer. These observations are a striking example of how electron–phonon interactions can be used to manipulate fundamentally important charge and energy transfer processes in hybrid perovskites.     

Neutron scattering study of pentanol solubilization in sodium octanoate micelles

We extend a previous small-angle neutron scattering study of sodium octanoate (NaC₈) micelles to the ternary system sodium octanoate/pentanol/water. The use of contrast variation through selective deuteration of individual components together with explicit computation of interference effects, permits us to deduce the location of pentanol (C₅OH) in the micelles. Our main conclusion is that, although the micelles grow as (C₅OH) is solubilised, there is no concomitant variation in the NaC₈ aggregation number. At low alcohol concentrations, the C₅OH is located near the NaC₈ polar heads, while at higher concentration the -OH groups are distributed throughout the micellar core.     

The initial oxidation of magnesium: an in situ study with XPS,HERDA and ellipsometry

The initial oxidation of magnesium at oxygen partial pressures between 1.3 × 10^?8 and 1.3 × 10^?5 Pa and at temperatures ranging from 273 to 550 K has been investigated in situ with X‐ray photoelectron spectroscopy (XPS), ellipsometry and high resolution elastic recoil detection analysis (HERDA). Quantitative analysis of the XPS spectra showed a clear oxygen deficiency with respect to MgO for the initial oxide. HERDA measurements confirmed this relatively low oxygen content in the thin oxide layers formed. Ellipsometry measurements showed that the electronic structure of the initially formed oxide differs significantly from that of bulk MgO. The band gap values at room temperature for the oxide layers investigated are clearly smaller than the value for bulk MgO. Copyright © 2006 John Wiley & Sons, Ltd.     

Aggregation processes of biomolecules in presence of trehalose

Among disaccharides, trehalose, a naturally-occurring glass-forming disaccharide, is particularly effective in terms of its ability to preserve several organisms under stress conditions. The present work is aimed to investigate the bioprotective action of trehalose on lysozyme as a function of temperature. In order to extract quantitative information about the dimensional changes of the proteins, we performed Small Angle Neutron Scattering measurements on lysozyme/D₂O solutions in absence and in presence of the disaccharide. The findings emphasise the capability of trehalose to stabilise the protein, activating aggregation processes.     

Application of Functionalized Ag Nanoparticles for the Determination of Proteins at Nanogram Levels Using the Resonance Light Scattering Method

A novel method for the determination of proteins in aqueous solutions has been developed based on the enhancement of resonance light scattering (RLS) of Ag nanoparticles in the presence of proteins. Factors including acidity of the media, concentration of Ag hydrosol, reaction time, temperature, and interference of non-protein substances were investigated. Under the optimal conditions, with the enhanced RLS signals at 452nm, the linear ranges of calibration curves were 0–0.8µgmL^–1 for bovine serum albumin (BSA), 0–1.2µgmL^–1 for human serum albumin (HSA), and 0–2.5µgmL^–1 for human -IgG (-IgG), respectively. The detection limits were 1.3ngmL^–1 for BSA, 10ngmL^–1 for HAS, and 5.7ngmL^–1 for -IgG.This method has been applied to the analysis of synthetic samples and real human serum samples, and the results were in good agreement with those reported by the hospital, indicating that the method presented here is not only sensitive and simple, but also reliable and suitable for practical applications.     

Polarization of coherent synchrotron radiation from an electron beam rotating in a plasma

After eliminating reflections from the walls of the plasma container, we observed polarization of the coherent synchrotron radiation from a relativistic electron beam rotating in a plasma. Several features of the polarization agree well with calculations based on the single particle synchrotron radiation theory. A particular polarization ratio (Fig. 3) does not, however. We deduce from this direct diffraction of the radiation by the beam electrons. This is strong evidence for beam-particle bunches of size cm. Also, there must be some absorption of the extraordinary wave to account for the observations. We suggest a way to apply these results to measure the pitch angle of the beam.Work supported by Army Research Office.     

Global Stability to Steady Supersonic Rayleigh Flows in One-Dimensional Duct∗

Heat exchange plays an important role in hydrodynamical systems, which is an interesting topic in theory and application. In this paper, the authors consider the global stability of steady supersonic Rayleigh flows for the one-dimensional compressible Euler equations with heat exchange, under the small perturbations of initial and boundary conditions in a finite rectilinear duct.     

长相关积累STAP处理的星载SAR-GMTI

目前多通道STAP多应用在短相干脉冲积累(CPI)模式的非成像体制雷达地杂波抑制,而对长CPI的SAR成像体制下的讨论较少。文中首先分析两种体制下STAP采用的不同信号模型,研究CPI对回波统计特性的影响和两种体制目标功率谱的差异。然后讨论SAR成像体制下STAP的应用,分析空时去相干性的影响。指出星载非平稳杂波环境中长CPI多普勒后处理的优势:既能有效降低杂波秩,减小样本支持数,同时减弱对空时去相关源的敏感性,又可得到动目标SAR图像。最后给出仿真实例。