组合式Si-PIN 14 MeV中子探测器

提出了一种在多片Si-PIN探测器中间用2mm厚的聚乙烯作为灵敏度增强介质,采用加法电路模式进行信号输出的组合式新型DT聚变中子(14MeV)探测技术原理. 这种组合的主要特点有： 1)大幅度提高了Si-PIN探测器的中子灵敏度和测量统计性; 2)提高了探测器的n/γ分辨本领; 3)在实现多个探测器信号相加的同时,组合探测器相对于单片探测器时间响应没有明显改变. 从实验及理论上对组合探测器的14MeV中子及1.25MeV γ灵敏度、n/γ分辨,时间特性和测量统计性进行了研究. 关键词： Si-PIN半导体探测器 灵敏度 n/γ分辨 时间响应     

高蛋白食物—螺旋藻

螺旋藻为原核生物。其所含蛋白质的质量和数量均为植物世界之冠;尚含各种维生素和生长因子;细胞壁易被人体消化;风味可口;无毒性。     

扫描近场光学显微镜对纳米结构的观察

光学显微镜在人们认识微观世界的过程中一直扮演着非常重要的角色．随着认识的深入，对空间分辨率的要求也越来越高．但是众所周知，普通光学显微镜（远场情况下）的分辨率受光的衍射效应所限制，一般可表达为0．61A／N．A．（约等于A／2，A为照射光的波长，N．A．为数值孔径）     

具有多重解的非线性Robin问题的奇摄动[英文]

本文利用边界层法，研究了具有多重解的非线性Robin问题εx″ f(t,x)x′ g(t,x)=0,0≤t≤1,x′(0,ε）-ax(0,ε)=A,x′(1,ε） bx(1,ε）=B其中ε为正的小参数。在适当的假设下，我们通过给出外部解展开式系数的一般表达式，得到了退化问题的边值为某方程的多重根时的渐近解，推广了有关结果。     

One-step separation and purification of 3,4-dihydroxyphenyllactic acid, salvianolic acid B and protocatechualdehyde from Salvia miltiorrhiza Bunge by high-speed counter-current chromatography

Three kinds of polyphenols of Salvia miltiorrhiza Bunge, 3,4-dihydroxyphenyllactic acid, salvianolic acid B and protocatechualdehyde, were separated and purified in one step with solvent system n-hexane-ethyl acetate-methanol-acetic acid-water (1:6:1.5:1.5:8) by high-speed counter-current chromatography. Acetic acid was successfully used to increase the partition of high polar target compounds in organic phase to modify partition coefficient value. 3,4-Dihydroxyphenyllactic acid, salvianolic acid B and protocatechualdehyde were purified from 100mg water extracted crude sample of Salvia miltiorrhiza Bunge at purity of 97.6%, 94.2% and 98.2% and at yield of 98.6%, 73.6% and 90.2%. High-speed counter-current chromatography together with organic/aqueous solvent system supplied an efficient method to purify water-soluble compounds directly from crude samples of traditional Chinese medicines.     

大气环境下氦气等离子体中化学过程数值模拟

建立一个大气化学程序用以模拟大气压下（地面附近）或低压（高空）情况下混合气体（氦气中混入少量空气）中产生等离子体后的化学过程。给出了电子寿命和主要带电粒子的随时间演化图。电子寿命在大气压下要长于大气等离子体，但在低压情况下这个结论不成立。电子数密度在一很长一段时间内不服从指数衰减规律。     

高效液相色谱法同时测定生物质乳酸发酵液中有机酸及糖类化合物

建立了高效液相色谱(HPLC)同时测定生物质乳酸发酵液中有机酸及糖类的分析方法。使用Bio-Rad Aminex HPX-87H色谱柱,以5 mmol/L的H2SO4为流动相,在柱温55 ℃,流速0.6 mL/min条件下,采用示差折光检测器进行检测。结果表明,该方法可在17 min内实现发酵液中各种有机酸和糖类化合物等的完全分离与定量,6种有机酸和3种糖类化合物在0.15～5.19 g/L范围内的线性关系良好,回归方程的线性相关系数在0.9998以上。将该法用于米根霉发酵液的检测,两个水平的加标回收率为96.91%～103.11%,相对标准偏差(n=6)为0.81%～4.61%。该法适用于微生物发酵液中多种有机酸和糖类的快速、高效分离和定量测定。     

Monomodal polyelectrolyte complex nanoparticles of PDADMAC/Poly(styrenesulfonate): preparation and protein interaction

The binding of the model proteins HSA, LYZ and MYO to PEC nanoparticles is reported. PEC particles were prepared by mixing solutions of PDADMAC either with PSS or PMA-MS, followed by consecutive centrifugation. Monomodal anionic (PEC-1.50) and cationic (PEC-0.66) PEC particles were obtained using non-stoichiometric mixing ratios. PEC/protein conjugates were prepared by adding charged protein solutions to dispersions of respective like charged PEC particles, followed by one centrifugation step. Mixing proteins and PEC particles under attractive conditions led to flocculation of the dispersion. From CD, DLS and AFM the following trend for protein binding at PEC particles under repulsive conditions was obtained: HSA/PEC-1.50 > MYO/PEC-1.50 > LYZ/PEC-0.66. Protein uptakes up to 0.33 g x g(-1) (protein/PEC) (CD) and particle diameter enlargements up to 13 nm (AFM) were obtained at c(PROT) = 0.091 mg . mL(-1). Furthermore, novel spin coated films of PEC particles were interacted with proteins under both repulsive and attractive conditions. In-situ ATR FT-IR spectroscopy revealed that the adsorbed amount of HSA and LYZ under attractive conditions was significantly higher than under repulsive ones, which is analogous to protein adsorption at polyelectrolyte multilayers terminated either by polycation or polyanion. Similarly to the dispersed PEC/protein conjugates, under repulsive conditions the uptake of HSA was higher compared to LYZ. The shown protein uptake under repulsive conditions is related to concepts of mild enzyme or protein binding at nonbiogenic substrates.     

Analysis of Biological Samples Using Paper Spray Mass Spectrometry: An Investigation of Impacts by the Substrates, Solvents and Elution Methods

Paper spray has been developed as a fast sampling ionization method for direct analysis of raw biological and chemical samples using mass spectrometry (MS). Quantitation of therapeutic drugs in blood samples at high accuracy has also been achieved using paper spray MS without traditional sample preparation or chromatographic separation. The paper spray ionization is a process integrated with a fast extraction of the analyte from the raw sample by a solvent, the transport of the extracted analytes on the paper, and a spray ionization at the tip of the paper substrate with a high voltage applied. In this study, the influence on the analytical performance by the solvent–substrate systems and the selection of the elution methods was investigated. The protein hemoglobin could be observed from fresh blood samples on silanized paper or from dried blood spots on silica-coated paper. The on-paper separation of the chemicals during the paper spray was characterized through the analysis of a mixture of the methyl violet 2B and methylene blue. The mode of applying the spray solvent was found to have a significant impact on the separation. The results in this study led to a better understanding of the analyte elution, on-paper separation, as well as the ionization processes of the paper spray. This study also helps in establishing a guideline for optimizing the analytical performance of paper spray for direct analysis of target analytes using mass spectrometry.     

Determination of tritium in Li–Pb alloy irradiated by thermal neutrons with quantitatively analyzing the byproduct 4He

The mass of the tritium produced in ⁶Li(n,α)T reaction was obtained by quantitatively analyzing the byproduct ⁴He with mass spectrometer. The self-expending seal method was employed to quantitatively prepare the Li–Pb alloy targets in room temperature. They were irradiated for 2 h in two rabbit irradiation channels in Xi’an pulsed reactor and measured after cooling 15 days. A sample purifying unit was set up to get rid of the hydrogen isotopes to remarkably reduce the interference to helium isotopes when measuring. And the sample disposal platform including purifying unit was testified with simulative gas and nature atmosphere. The targets were melted at 700 °C to release most of the ⁴He atoms which were measured by adding dilution gas ³He. And it was testified that ⁴He had released completely by repetitiously melting the targets. This approach had solved the problem that the tritium couldn’t be accurately determined by directly analyzing it because of non-complete releasing from lithium alloy.