A new pseudo rubrene analogue with excellent film forming ability

A novel pseudo rubrene analogue,6,11-di(thiophen-2-yl)-tetracene-5,12-dione (DTTDO) was synthesized,in which two thienyl groups and two carbonyl groups replacing four phenyl groups in the rubrene molecule were connected to the backbone of tetracene.This compound was characterized by single crystal X-ray structure analysis,thermogravimetric analysis,absorption spectra and electrochemical measurements.Unlike rubrene,DTTDO exhibited excellent film forming ability by normal vacuum deposition,indicating its prom...     

不确定参数闭环控制系统特征值的区间分析

运用区间理论,讨论了区间参数的结构振动控制问题,给出了求解闭环系统区间特征值的一种方法．基于区间参数导出了区间刚度矩阵和质量矩阵,然后利用矩阵摄动理论和区间扩张理论,推导了复区间特征值上下界估计的算法．这些结果是从二阶系统的左右特征向量出发得到的．将该文方法应用到悬臂梁的控制问题,数值结果表明它是有效的．     

Receptivity to free-stream disturbance waves for hypersonic flow over a blunt cone

A high-order shock-fitting finite difference scheme is studied and used to do direction numerical simulation (DNS) of hypersonic unsteady flow over a blunt cone with fast acoustic waves in the free stream, and the receptivity problem in the blunt cone hypersonic boundary layers is studied. The results show that the acoustic waves are the strongest disturbance in the blunt cone hypersonic boundary layers. The wave modes of disturbance in the blunt cone boundary layers are first, second, and third modes which are generated and propagated downstream along the wall. The results also show that as the frequency decreases, the amplitudes of wave modes of disturbance increase, but there is a critical value. When frequency is over the critial value, the amplitudes decrease. Because of the discontinuity of curvature along the blunt cone body, the maximum amplitudes as a function of frequencies are not monotone. Supported by the National Natural Science Foundation of China (Grant Nos. 10632050 and 10502052)     

Prediction of mucin-type <Emphasis Type="Italic">O</Emphasis>-glycosylation sites by a two-staged strategy

The mucin-type O-glycosylation of a protein is an important type of protein post-translational modification. This process is mediated by a family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases which transfer the N-acetylgalactosamine (GalNAc) to the serine or threonine residues with unknown specificity. In order to determine the glycosylation sites of a given protein, we present a two-staged prediction method here, which first determines whether a protein is a glycoprotein, and then determines the glycosylation sites of a protein that has been predicted to be glycosylated in the first stage. In the first stage, a protein is encoded by the protein families in PFAM, which is a collective annotated database of classified protein families; then it is predicted by a predictor trained by the training set. In the second stage, nonapeptides of the predicted mucin-type glycoproteins, with serine or threonine residues at their fifth sites, are represented by indices in AAIndex. Then, it is predicted whether the nonapeptides are attached by GalNAc by a predictor, which is constructed with features selected by feature selection methods [Maximum Relevance Minimum Redundancy (mRMR) method and Incremental Feature Selection method]. The prediction accuracy of the first stage is 94.9% validated by Leave-One-Out validation method; the prediction accuracy of the second stage is 99.4%. These results show that this method is valuable to study the mucin-type O-glycosylation. The analysis of the features used to construct the predictor of the second stage confirms the previously obtained results from other groups. The residues at position −1 and +3 have great impact on the prediction. Among other amino acid indices, the indices about alpha and turn propensities and indices about hydrophobicity of the residues in nonapeptide also influence the recognition of the GalNAc transferases. A web server is available at .     

An overview of design for CSNS/RCS and beam transport

The China Spallation Neutron Source (CSNS) is the first accelerator-based pulsed neutron source in China. Its accelerators are made up of an 80 MeV H⁻ linac, a Rapid Cycling Synchrotron (RCS) and two beam transport lines. RCS accumulates and accelerates protons to the design energy of 1.6 GeV, and extracts high energy beam to strike the target. The overview of RCS is presented, and the key problems of the physics design are discussed. The two beam transport lines, from linac to RCS and from RCS to the target, are also introduced.

     

石英晶体微天平的新进展

石英晶体微天平（quartz crystal microbalance,QCM）是一种对界面变化敏感的仪器,它已经在物理、化学、生物学、药物学、临床医学、环境科学等学科的界面问题研究中得到了一定的应用.然而,QCM在液相下的应用和推广一直受限于QCM数据定量解释的困难.为此,科研工作者发展了多种高级的QCM,比如带阻抗分析功能的QCM（impedance QCM,i-QCM）或带能量耗散监测功能的QCM（QCM with dissipation,QCM-D）,同时还发展了许多相应的理论模型.但是,对于多数生物、化学工作者来说,这些理论过于复杂.这极大地限制了QCM的推广和潜力发挥.本文以我们小组在QCM方面的研究工作为线索,对已报道的分析方法、模型和方程按5类应用条件进行了整理,给出了明确的界定标准：它们是：1,固-气界面;2,牛顿流体;3,固-液界面的薄膜;4,固-液界面厚膜;5,固-液界面超厚膜.对于每一类情况,我们将用通俗易懂的语言描述如何对QCM数据进行简化却又保证研究精度需要的定量分析.对于液态环境下的QCM数据的分析,我们着重介绍了＂固化水层＂模型,该模型允许QCM在一定的条件下成为一把＂分子尺＂,工作范围从几个纳米到数百纳米.该分子尺在多个创新界面问题研究中得到很好的应用.最后,我们从理论上分析了QCM作为生物传感器的先天缺陷--因基于面均质量检测的原理,QCM技术对溶液中蛋白的检测下限仅在1μg mL-1数量级.进一步,我们探索了QCM的发展方向和潜在应用领域,希望籍此能进一步推广QCM在各个学科界面问题中的研究应用.     

Study of third-order nonlinear susceptibility of polySchiff base containing triphenylamine

PolySchiff base containing triphenylamine has been synthesized by polycondensation and character-ized by FT-IR,NMR,UV-visible spectrometer. Measurements of the third-order optical nonlinear sus-ceptibility χ(3) by Z-scan technique have shown that the large nonlinearity is dominated by the two-photon absorption in PSB. The sign and size of real part Reχ(3) ,nonlinear refractive index n2 have been measured with the condition of 532 nm,8 ns-duration pulses to be -1.23×10-10 esu,-3.06×10-12 esu;nonlinear absorption index β and size of image part Imχ(3) to be 3.63×10-10 m/W,1.15×10-11 esu,respec-tively,so the third-order nonlinear susceptibility χ(3) is 1.19×10-11 esu. The value is larger than other polymers reported. PSB is self-focusing material and has potential application in nonlinear optic field.     

The change in thickness of the solidified liquid layer rather than the immobilized mass determines the frequency response of a quartz crystal microbalance

The "solidified liquid layer" model has been examined using a quartz crystal microbalance(QCM) with a polymeric matrix.The model is shown to give a reasonable explanation for the following experimental observations:(i) The opposite response of the QCM and surface plasmon resonance(SPR) for the activation process;(ii) the marked difference in the responses for IgG/anti-IgG interaction between QCM and SPR.Theoretical analysis and experimental results indicated that QCM is sensitive to the thickness change of the "solidified liquid layer" but not the mass of captured biomolecules(i.e.,the immobilized mass),implying caution must be taken in interpreting QCM results.