基于GPU的可视化测量仪器软件设计

提出利用显卡图形处理单元(Graphics Processing Units, GPU)的并行信息处理能力解决仪器软件在执行海量数据处理、建模、渲染以及交互所面临的开销过大的难题,基于DirectX 11的计算着色器(Compute Shader,CS)实现海量测量数据的处理和建模以及高速推送渲染,建立在GPU内实现海量数据模型上点的拾取模块,以提高仪器可视化测量中的交互执行。实验比对证实了基于GPU的可视化测量仪器软件的高执行效率。研究为挖掘可视化测量仪器硬件能力、合理配置仪器CPU与GPU开销、在整体上提高仪器运行效率提供了一条有价值的技术路径。     

Origin of intrinsic 3(10)-helix versus strand stability in homopolypeptides and its implications for the accuracy of the Amber force field

Current all-atom force fields often fail to recognize the native structure of a protein as the lowest free energy minimum. One possible cause could be the mathematical form of the potential based on the assumption that the conformation of a residue is independent of its neighbors. Here, using quantum mechanical (QM) methods (MP2/6-31g**//HF/6-31g** and MP2/cc-pVDZ//cc-pVDZ//HF/cc-pVDZ), the intrinsic correctness of the gas phase terms (without solvation) of the Amber ff03 and ff99 potentials are examined by testing their ability to reproduce the relative 3(10)-helix versus extended structure stabilities in the gas phase for 1-7-residue alanine, valine, leucine, and isoleucine homopolypeptides. The 3(10)-helix versus extended state stability strongly depends on chain length and less on the amino acid identity. The helical conformation becomes lower in energy than the extended conformation for all tested peptides longer than two residues, and its stability increases with the increase of chain length. The ff03 potential better describes the 3(10)-helix versus extended state energy than ff99 and also reproduces the curvature of the relative helix-extended state energies. Therefore, the mathematical form of the Amber potential is sufficient to describe the local effect of 3(10)-helix versus extended structure stabilization in the gas phase. However, the energy curves are shifted and the backbone geometries differ compared with the QM results. This may cause significant geometric discrepancies between native and predicted structures. Therefore, extant molecular mechanics force fields, such as Amber, need refinement of their parameters to correctly describe helix-extended state energetics and geometry of major conformations.     

Monitoring the traceability of the pH of a primary tetraborate buffer: comparison of results from primary and secondary apparatus

This paper reports evaluation of the behaviour of different combined glass electrodes applied to measurement of the pH of a primary, 0.01 mol kg⁻¹, tetraborate buffer. Measurements were first performed by use of a primary Harned cell (at 15, 25, and 37 °C); these results were then compared with those obtained for the same solution by use of three combined glass electrodes (25 °C) with different membranes and liquid-junction designs, calibrated by use of commercial pH-metric buffers. The pH of the same solution was also measured in terms of the molal concentration of hydrogen ions, using acid–base titration to evaluate the formal potential difference K of each cell at fixed ionic strength, I, adjusted by addition of KCl or Et₄NI (tetraethylammonium iodide). The reference value from primary measurement, paH = 9.171, was slightly closer to the mean value obtained by determination of concentration, rather than that obtained by direct measurement of activity; the differences were smaller than the extended uncertainty characteristics of the secondary measurements. The importance of evaluation of the ionic strength of the solution under study is emphasised. We verified that for tetraborate buffer slight modification of the value of I used to calculate γ _i (the activity coefficient of a single ion) in the calculation of paH from the acidity function at zero molality of chloride can significantly affect the reference value of the calibrator tool. This is true, in general, for low values of the ionic strength, such as those considered in this work; an approximate value of I can then cause distortions along the pH traceability chain. Application of the concepts of thermodynamics to this traceability chain is discussed.     

A Bayesian approach to assess data from radionuclide activity analyses in environmental samples

A Bayesian statistical approach is introduced to assess experimental data from the analyses of radionuclide activity concentration in environmental samples (low activities). A theoretical model has been developed that allows the use of known prior information about the value of the measurand (activity), together with the experimental value determined through the measurement. The model has been applied to data of the Inter-laboratory Proficiency Test organised periodically among Spanish environmental radioactivity laboratories that are producing the radiochemical results for the Spanish radioactive monitoring network. A global improvement of laboratories performance is produced when this prior information is taken into account. The prior information used in this methodology is an interval within which the activity is known to be contained, but it could be extended to any other experimental quantity with a different type of prior information available.     

A chemiluminescence biochemical oxygen demand measuring method

A new chemiluminescence biochemical oxygen demand (BOD_CL) determining method was studied by employing redox reaction between quinone and Baker's yeast. The measurement was carried out by utilizing luminol chemiluminescence (CL) reaction catalyzed by ferricyanide with oxidized quinone of menadione, and Saccharomyces cerevisiae using a batch-type luminometer. In this study, dimethyl sulfoxide was used as a solvent for menadione. After optimization of the measuring conditions, the CL response to hydrogen peroxide in the incubation mixture had a linear response between 0.1 and 100 μM H₂O₂ (r² = 0.9999, 8 points, n = 3, average of relative standard deviation; R.S.D._av = 4.22%). Next, a practical relationship between the BOD_CL response and the glucose glutamic acid concentration was obtained over a range of 11-220 mg O₂ L⁻¹ (6 points, n = 3, R.S.D._av 3.71%) with a detection limit of 5.5 mg O₂ L⁻¹ when using a reaction mixture and incubating for only 5 min. Subsequently, the characterization of this method was studied. First, the BOD_CL responses to 16 pure organic substances were examined. Second, the influences of chloride ions, artificial seawater, and heavy metal ions on the BOD_CL response were investigated. Real sample measurements using river water were performed. Finally, BOD_CL responses were obtained for at least 8 days when the S. cerevisiae suspension was stored at 4 °C (response reduction, 69.9%; R.S.D. for 5 testing days, 18.7%). BOD_CL responses after 8 days and 24 days were decreased to 69.9% and 35.8%, respectively, from their original values (R.S.D. for 8 days involving 5 testing days, 18.7%).     

n-Hg_(0.80)Mg_(0.20)Te界面积累层中二维电子气的输运特性研究

通过变磁场霍耳测量研究了MBE生长的Hg0 .80 Mg0 .2 0 Te薄膜在 1 5— 2 5 0K温度范围内的输运特性 .采用迁移率谱 (MS)和多载流子拟合过程 (MCF)相结合的方法对实验数据进行了分析 ,由该方法获得的结果和ShubnikovdeHass(SdH)振荡测量的结果都证明材料中存在二维 (2D)电子和三维 (3D)电子 .其中 2D电子主要来自于Hg1-xMgxTe CdTe的界面积累层或Hg1-xMgxTe与真空界面附近的积累层 .3D电子迁移率随温度的变化关系表明了Hg1-xMgxTe中的电子散射机理与Hg1-xCdxTe中的非常相似 :在低温下电离杂质散射 (考虑了屏蔽效应 )起主导地位 ,而温度在 10 0K以上时 ,晶格散射占主导地位 .     

等离子体电极电光开关特性参数测量

 建造一套电光开关参数测量系统,具备时间分辨、空间分辨及全口径平均测量能力。介绍了240mm×240mm等离子体电极普克尔盒电光开关特性参数及测量光路,并给出了实验测量结果。     

合肥电子储存环基本参数的测量

 为了给改造后的合肥储存环留下参考数据,同时为了找到储存环存在的物理问题,储存环特性参数首次被系统测量,它们是动量扩张因子、色散函数、自然色品、校正色品和中心频率。     

利用激光并采用热释电探测器实时测量比辐射率及温度的系统

设计了一种利用半导体激光器InGaAs/I作为光源 ,采用钽酸锂热释电探测器作为光接收元件 ,以 80 31单片机为核心的中、高温物体比辐射率及温度的实时测量系统。该系统主要由光学发射与接收系统、信号放大与处理系统和显示系统三部分组成。文中还介绍了该系统的基本原理及结构 ,分析了其中的技术难点及其解决方法 ,讨论了系统的灵敏度、比辐射率与温度的测量精度。分析表明 :对 42 7℃的抛光钢铸件而言 ,系统的最小鉴别温差为 0 32K ,比辐射率的测量精度σελ=6 5× 10 -3 ,|σελ/ελ|=1 2 0 % ;温度的测量精度σT =1 0 6K ,|σT/T|=0 15 2 %。     

真空腔测量空气折射率的方法及精度分析

空气折射率的测量及补偿效果在高精度激光干涉测量中起着“瓶颈”作用。分析了空气折射率的补偿原理 ,研究了用预抽气真空腔测量和补偿空气折射率的测量原理、方法及装置 ,分析了该方法对测量误差产生的原因。最后对测量精度作出了估计。