CdTe量子点与罗丹明B水溶液体系下的双光子激发荧光共振能量转移

采用时间分辨荧光光谱技术研究了在双光子激发下不同尺寸的量子点与罗丹明B 之间的荧光共振能量转移. 研究结果表明, 在800 nm的双光子激发条件下, 体系间能量转移效率随着供体吸收光谱与受体荧光光谱的光谱重叠程度增加而增加; 理论分析表明, 供体和受体间的Förster半径增加是导致其双光子能量转移效率增大的物理原因. 同时, 研究了罗丹明B浓度对荧光共振能量转移效率的影响. 研究结果表明, 量子点的荧光寿命随着罗丹明B浓度的增加而减小; 量子点与罗丹明B之间的荧光共振能量转移效率随着罗丹明B浓度的增加而增加; 当罗丹明B浓度为3.0×10^-5 mol·L^-1时, 双光子荧光共振能量转移效率为40.1%.     

Back contact–absorber interface modification by inserting carbon intermediate layer and conversion efficiency improvement in Cu2ZnSn(S,Se)4 solar cell

Carbon layers have been employed as intermediate layers between Mo back contact and Cu₂ZnSn(S_1–xSe_x)₄(CZTSSe) absorber film prepared by sol–gel and post‐selenization method. Carbon layers with appropriate thickness can significantly inhibit the formation of MoSe₂ and voids at bottom region of the absorber, and therefore reduce the series resistance remarkably. The conversion efficiency can be boosted by the introducing of the carbon layer from 6.20% to 7.24% by enhancement in short current density, fill factor and open voltage in comparison to the reference sample without carbon layer. However, excess thickness of carbon layer will worse device performance due to the deteriorated absorber crystallinity. In addition, the time‐resolved photoluminescence analysis shows that inserting the carbon layer with suitable thickness does not introduce recombination and lower minority lifetime. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

NFZ-10工业辐照电子直线加速器

研制的电子直线加速器ＮＦＺ－１０的辐照加工能力相当于３０ＰＢｑ的６０Ｃｏ源，电子束能量为４～１２ＭｅＶ，平均束功率为３ｋＷ，扫描宽度为１ｍ，能量不稳定度≤±０．５％，束流不稳定度≤±０．６％，扫描不均匀度≤±２．５％。ＮＦＺ－１０加速器已被用于辐照各种电力半导体器件，一年多来运行稳定可靠并获得较好的经济效益。     

Processes limiting the rate of response in photorefractive composites

The processes limiting the rate of response of highly diffractive, reorientationally enhanced photorefractive polymer composite materials are identified from a series of degenerate four wave mixing and Mach–Zehnder interferometric measurements. In the regime of low intensity writing beams charge generation limits the rate of holographic grating formation, but at higher intensities charge transport or reorientation of dye molecules can restrict the rate of grating formation more strongly. A grating risetime of 540 ms is observed in a composite of high dye content with high reorientational mobility of the dye molecules. In this case it is proposed that the charge carrier mobility of the doped poly(N-vinylcarbazole):2,4,7-trinitro-9-fluorenone (PVK:TNF) matrix is the principal limiting factor in grating response rates.     

Two-Dimensional Potts Model and Annular Partitions

Using the random cluster expansion, correlations of the Potts model on a graph can be expressed as sums over partitions of the vertices where the spins are fixed. For a planar graph, only certain partitions can occur in these sums. For example, when all fixed spins lie on the boundary of one face, only noncrossing partitions contribute. In this paper we examine the partitions which occur when fixed spins lie on the boundaries of two disjoint faces. We call these the annular partitions, and we establish some of their basic properties. In particular we demonstrate a partial duality for these partitions, and show some implications for correlations of the Potts model.     

Triaxial superdeformation in Lu

High-spin states in ¹⁶³Lu have been investigated using the Euroball spectrometer array. The previously known superdeformed band has been extended at low and high energies, and its connection to the normal-deformed states has been established. From its decay the mixing amplitude and interaction strength between superdeformed and normal states are derived. In addition, a new band with a similar dynamic moment of inertia has been found. The experimental results are compared to cranking calculations which suggest that the superdeformed bands in this mass region correspond to shapes with a pronounced triaxiality (γ≈±20°).     

A novel local PCA-based method for detecting activation signals in fMRI.

A novel local principal component analysis (LPCA) technique is presented for activation signal detection in functional magnetic resonance imaging (fMRI) without explicit knowledge about the shape of the model activation signal. Unlike the traditional PCA methods, our LPCA algorithm is based on a measure of separation between two clusters formed by the signal segments in active periods and inactive periods, which is computed in an eigen-subspace. In addition, we only applied PCA to the temporal sequence of each individual voxel instead of applying PCA to the fMRI data set. In our algorithm, we first applied a linear regression procedure to alleviate the baseline drift artifact. Then, the baseline-corrected temporal signals were partitioned into active and inactive segments according to the paradigm used for the fMRI data acquisition. Principal components were computed from all these segments for each voxel by PCA. By projecting the segments of each voxel onto a linear subspace formed by the corresponding most dominant principal components, two separate clusters were formed from active and inactive segments. An activation measure was defined based on the degree of separation between these two clusters in the projection space. We show experimental results on the activation signal detection from various sets of fMRI data with different types of stimulation by using the proposed LPCA algorithm and the standard t-test method for comparison. Our experiments indicate that the LPCA algorithm in general provides substantial signal-to-noise ratio improvement over the t-test method.     

Observability of lag synchronization of coupled chaotic oscillators

Lag synchronization is a recently discovered theoretical phenomenon where the dynamical variables of two coupled, nonidentical chaotic oscillators are synchronized with a time delay relative to each other. We investigate experimentally and numerically to what extent lag synchronization can be observed in physical systems where noise is inevitable. Our measurements and numerical computation suggest that lag synchronization is typically destroyed when the noise level is comparable to the amount of average system mismatch. At small noise levels, lag synchronization occurs in an intermittent fashion.     

Decoding information by following parameter modulation with parameter adaptive control

It has been proposed to realize secure communication using chaotic synchronization via transmission of a binary message encoded by parameter modulation in the chaotic system. This paper considers the use of parameter adaptive control techniques to extract the message, based on the assumptions that we know the equation form of the chaotic system in the transmitter but do not have access to the precise values of the parameters which are kept secret as a secure set. In the case in which a synchronizing system can be constructed using parameter adaptive control by the transmitted signal and the synchronization is robust to parameter mismatches, the parameter modulation can be revealed and the message decoded without resorting to exact parameter values in the secure set. A practical local Lyapunov function method for designing parameter adaptive control rules based on originally synchronized systems is presented.     

基于FPGA的储存环束流轨道联锁系统设计

上海光源储存环束流轨道联锁系统是加速器机器联锁保护系统(MPS)的重要组成部分,针对日常供光和机器研究的需求,需要对束流位置测量系统前各Libera电子学输出的联锁信号进行标记,以区分联锁信号的先后顺序和误报的联锁信号,同时触发所有Libera电子学前锁存逐圈（TBT）数据。新的联锁系统将所有联锁信号通过光纤传输汇总至FPGA数据采集板卡进行甄别,并将该系统集成储存环EPICS控制系统中。实验室测试显示该系统能够能够分辨数十ns范围内模拟的联锁信号,同时输出特定的触发信号至对应的Libera电子学,表明该系统达到设计要求。