基于NMR的代谢组学方法最新进展及应用

代谢组学的定义“对病理/生理刺激以及基因改变时生物体系动态的代谢响应进行多参数的定量测量”已被广泛接受. 本文对代谢组学研究的最新进展及其在系统生物学中所发挥的作用进行了综述. 在代谢组学方法研究方面,着重讨论了现代NMR技术的进展及其对代谢组学所产生的影响,同时也包括用于分离的HPLC及其与质谱的连用技术. 对代谢组学广泛应用的概述,主要包括：对正常生理变化的新认识;药物和其他外源性化学物质的副作用;外源性物质对环境污染的影响以及逐渐增多的代谢组学方法在疾病检测中应用.     

Three-Dimensional Numerical Analysis for Millimeter Wave TWTs

Based on Macro–particle model, the electron beam can be subdivided into 3D Macro–particles to calculate space–charge forces and 3D large–signal working equations are obtained. Finally, the numerical results for a uniform magnetic focusing field are given.     

Investigation of the effect of larger monolayer coverage in the active layer of bilayer InAs/GaAs quantum-dot structure and effects of post-growth annealing

Morphological and optical properties of MBE-grown single and bilayer InAs/GaAs quantum-dot heterostructure with comparatively larger monolayer coverage (∼3.3 ML) are investigated. As compared to the similar single-layer quantum-dot (SQD) structure, the bilayer quantum-dot (BQD) structure showed a more uniform spatial distribution and increased size homogeneity of the dots. It also exhibited longer wavelength photoluminescence (PL) emission at room temperature, with the peak at a wavelength (1.34 μm) in the infrared communication window. The shift seen in the low temperature PL emission peak, even after annealing the BQD samples at temperatures up to 700°C, is negligible. However, the BQD samples showed an activation energy lower than that of the SQD sample, attributed to the In/Ga interdiffusion with the thin (8.5 nm thick) GaAs spacer layer during the growth process. Despite that, the higher thermal stability demonstrated by the BQD structure, along with a lower linewidth, makes the bilayer quantum dots a desirable proposition for efficient lasing devices requiring strict tolerances on operating wavelength.     

基于LabVIEW的LED三维特性检测的研制

为了解决传统配光曲线只能反映LED发光二维特性、立体感太差及不便于人为观察比较的难题,提出一种新的基于高级图像编程语言(LabVIEW)的LED三维特性(光强空间分布)快速检测方法。在传统光强空间分布检测方法的基础上,采用多路光度探测单元同步测试,可在0.2s内一次性由31个探测单元同步测得LED光源的二维光强空间分布（配光曲线）。通过增加旋转机构转动待测LED样品,依次测得i(i=180°/α)条配光曲线。最后由自研软件将i条配光曲线进行数据汇总处理,便可得到LED光源的光强空间分布的三维立体图。该检测方法具有速度快、精度高、信息量大等优点,并且具有实时性和直观性。     

Renormalization group for network models of quantum Hall transitions

We analyze in detail the renormalization group flows which follow from the recently proposed all orders β functions for the Chalker–Coddington network model. The flows in the physical regime reach a true singularity after a finite scale transformation. Other flows are regular and we identify the asymptotic directions. One direction is in the same universality class as the disordered XY model. The all orders β function is computed for the network model of the spin quantum Hall transition and the flows are shown to have similar properties. It is argued that fixed points of general current–current interactions in 2d should correspond to solutions of the Virasoro master equation. Based on this we identify two coset conformal field theories osp(2N|2N)₁/u(1)₀ and osp(4N|4N)₁/su(2)₀ as possible fixed points and study the resulting multifractal properties. We also obtain a scaling relation between the typical amplitude exponent α₀ and the typical point contact conductance exponent X_t which is expected to hold when the density of states is constant.     

Electronic structure effects on B K‐edge XANES of minerals

In order to assess the usability of X‐ray absorption near‐edge structure (XANES) for studying the structure of BO_n‐containing materials, the dependence of theoretical XANES at the B K‐edge on the way the scattering potential is constructed is investigated. Real‐space multiple‐scattering calculations are performed for self‐consistent and non‐self‐consistent potentials and for different ways of dealing with the core hole. It is found that in order to reproduce the principal XANES features it is sufficient to use a non‐self‐consistent potential with a relaxed and screened core hole. Employing theoretical modelling of XANES for studying the structure of boron‐containing glasses is thus possible. The core hole affects the spectrum significantly, especially in the pre‐edge region. In contrast to minerals, B K‐edge XANES of BPO₄ can be reproduced only if a self‐consistent potential is employed.     

Phase Covariant Channel: Quantum Speed Limit of Evolution

The quantum speed of evolution for the phase covariant map is investigated. This involves absorption, emission, and dephasing processes. The maps under various combinations of the above processes are considered to investigate the effect of phase covariant maps on quantum speed limit time. For absorption-free phase covariant maps, combinations of dissipative and CP-(in)divisible (non)-Markovian dephasing noises are considered. The role of coherence-mixedness balance on the speed limit time is checked in the presence of both vacuum and finite temperature effects. The rate at which Holevo's information changes and the action quantum speed of evolution for specific cases of the phase covariant map are also investigated.     

Effects of PEDOT:PSS and crystal violet interface layers on current-voltage performance of Schottky barrier diodes as a function of temperature and variation of diode capacitance with frequency

In this study, diode applications of Crystal Violet (CV) and PEDOT materials were studied. The Ni/p-Si/Al, Ni/CV/p-Si/Al and Ni/PEDOT:PSS/CV/p-Si/Al diodes were fabricated. The I–V (current-voltage) characteristics of all diodes were analyzed at room temperature, it was determined that the PEDOT:PSS and CV materials improved the basic diode parameters. Also, I–V characteristics of Ni/PEDOT:PSS/CV/p-Si/Al of diode were investigated for different temperature values. It has been determined that the basic diode parameters are strongly dependent on temperature. It was determined that while the barrier height (Φ_b) increased with increasing temperature, the ideality factor (n) and the series resistance (R_s) values decreased. Using temperature-dependent measurements, it was determined that the potential barrier and ideality factor values at the contact interface has a double Gaussian distribution. In addition, C–V (capacitance-voltage) measurements of these diodes were analyzed depending on the frequency. It was found that the diode capacitance decreased with increasing frequency.     

Three-Dimensional FDTD Analysis of Chiral Discontinuities in the Waveguide

A simple finite difference time domain (FDTD) scheme for chiral media is developed for modeling the chiral discontinuities in the waveguide with the aid of the second-order backward finite difference. The accuracy of the FDTD scheme is demonstrated by the comparison between our calculated results and those in the literature for achiral and chiral media. Comparisons of characteristics between chiral and achiral discontinuities in the waveguide are presented at last.     

伸缩窗口傅里叶变换在三维形貌测量中的应用

为了克服窗口傅里叶变换在分析非平稳信号所存在的缺陷,基于窗口傅里叶变换技术提出了伸缩傅里叶变换法并应用于三维形貌测量中。通过对窗函数在空间尺度上引入伸缩变换,得到一个可调宽度的空间一频率窗,实现空间频率分辨率随光栅图像条纹频率变化自动可调的实时快速测量。该方法克服了窗口傅里叶变换分析中所有频率窗口的大小形状固定不变的缺点,适合复杂物体形貌的测量。给出了理论分析、计算机模拟以及实验研究结果。     

Characterization of spatial coherence of synchrotron radiation with non‐redundant arrays of apertures

A method to characterize the spatial coherence of soft X‐ray radiation from a single diffraction pattern is presented. The technique is based on scattering from non‐redundant arrays (NRAs) of slits and records the degree of spatial coherence at several relative separations from 1 to 15 µm, simultaneously. Using NRAs the spatial coherence of the X‐ray beam at the XUV X‐ray beamline P04 of the PETRA III synchrotron storage ring was measured as a function of different beam parameters. To verify the results obtained with the NRAs, additional Young's double‐pinhole experiments were conducted and showed good agreement.     

Synchrotron scanning photoemission microscopy of homogeneous and heterogeneous metal sulfide minerals

Scanning photoemission microscopy (SPEM) has been applied to the investigation of homogeneous and heterogeneous metal sulfide mineral surfaces. Three mineral samples were investigated: homogeneous chalcopyrite, heterogeneous chalcopyrite with bornite, and heterogeneous chalcopyrite with pyrite. Sulfur, copper and iron SPEM images, i.e. surface‐selective elemental maps with high spatial resolution acquired using the signal from the S 2p and Cu and Fe 3p photoemission peaks, were obtained for the surfaces after exposure to different oxidation conditions (either exposed to air or oxidized in pH 9 solution), in addition to high‐resolution photoemission spectra from individual pixel areas of the images. Investigation of the homogeneous chalcopyrite sample allowed for the identification of step edges using the topography SPEM image, and high‐resolution S 2p spectra acquired from the different parts of the sample image revealed a similar rate of surface oxidation from solution exposure for both step edge and a nearby terrace site. SPEM was able to successfully distinguish between chalcopyrite and bornite on the heterogeneous sample containing both minerals, based upon sulfur imaging. The high‐resolution S 2p spectra acquired from the two regions highlighted the faster air oxidation of the bornite relative to the chalcopyrite. Differentiation between chalcopyrite and pyrite based upon contrast in SPEM images was not successful, owing to either the poor photoionization cross section of the Cu and Fe 3p electrons or issues with rough fracture of the composite surface. In spite of this, high‐resolution S 2p spectra from each mineral phase were successfully obtained using a step‐scan approach.     

Multiplesite structure and photoluminescence properties of Eu3+ doped MgO nanocrystals

MgO:Eu³⁺ nanocrystals with average diameter around 15 nm were prepared via a facile combustion method under a weak reductive atmosphere at temperature as low as 300°C. The photoluminescence spectra showed that the MgO:Eu³⁺ nanocrystals emit white light, the hypersensitive transition (⁵ D ₀→⁷ F _j of Eu³⁺) emission was prominent in the emission spectra resulting from the noinversion symmetry local site at which Eu³⁺ ions were located. Two kinds of luminescence sites of Eu³⁺ are identified by means of the fluorescence decay and site-selective spectroscopy. The excitation and absorption spectra indicated that the absorption of surface state decreased with the increase of Eu³⁺ concentration, meaning that the surface defect decreased through Eu³⁺ doping for some of them located at the disordered sites near the surface or absorbed at the surface of MgO host. Meanwhile, absorptivity and CIE chromaticity coordinates of all samples were measured; the results were in accordance with the excitation and absorption spectra and photoluminescence spectra, respectively.     

Impact of ketone and amino on the inner shell of guanine

Removal of the functional groups of guanine, i.e. ketone and amino, one by one produces model molecules of hypoxanthine, 2‐aminopurine and unsubstituted purine. The impact of the ketone and amino moieties on guanine is revealed using their atomic‐site‐based inner‐shell electronic properties and spectra. A density functional theory based model has been employed to study the model molecules. Electronic properties, such as Hirshfeld charges and inner‐shell chemical shift, are found to be both site‐dependent and moiety‐dependent. The site‐based inner‐shell chemical shift of the species exhibits a simple linear correlation, although certain similarities among the model molecules regroup the species into two pairs of purine and 2‐aminopurine, as well as hypoxanthine and guanine.     

Almost product manifolds as the low energy geometry of Dirichlet branes

The European Physical Journal C - Any candidate theory of quantum gravity must address the breakdown of the classical smooth manifold picture of space-time at distances comparable to the Planck...