Supercritical fluid chromatography reduction of hydrogen/deuterium back exchange in solution-phase hydrogen/deuterium exchange with mass spectrometric analysis

The single biggest problem with solution-phase H/D exchange as a mass spectrometric probe of surface exposure in a protein (or protein complex) is back-exchange of H for D after the initial H/D exchange has been quenched. Back-exchange results in loss of pertinent data and also greatly hampers data analysis. Previously, very fast, cold (0-4 degrees C) HPLC was performed to help reduce back-exchange, but calculated back-exchange still averages approximately 30%. In this report, supercritical fluid chromatography replaces HPLC as the desalting/separation technique prior to mass analysis, providing a dramatic reduction in back-exchange compared to the fast, cold HPLC methods.     

中国制造业产品质量:基于技术含量视角的实证分析

利用WIOD数据库2000-2014年世界投入产出表,结合生产工序方法测算中国制造业的整体技术含量、国内技术含量和国内技术贡献率,基于技术含量视角分析中国制造业出口产品质量的动态变迁及其影响因素。研究发现:(1)中国制造业及其细分行业技术含量增速较快,但绝对量低于世界其他主要国家(地区),国内生产环节的技术含量有待进一步提升。(2)引进国外技术对制造业产品质量的影响具有“U”形特征,成本效应占优时,表现为负向作用;技术溢出效应占优时,表现为促进作用。随着国内技术含量的增加,国外技术引进的抑制作用开始显现,在技术密集型行业中,技术引进总体表现为抑制作用。(3)行业自主研发是出口产品质量升级的重要推动力,分别与国内技术以及行业开放具有互补效应,即自主研发可以增加行业对技术的消化吸收能力,提高技术溢出效应,且互补效应在资本密集型行业和技术密集型行业中更为显著。     

通控设备一体化测试诊断平台设计与实现

针对指挥系统通信控制设备种类多,测试指标繁杂,测试资源难以集成的问题研发一体化测试诊断平台。首先进行通控设备测试诊断平台的系统总体设计;其次对其关键技术进行研究,主要:包括基于自环与模拟的通控机混合测试技术,基于"软件无线电"的电台综合检测技术,基于指挥系统拓扑结构的网络测试技术等;最后对该检测平台的系统软硬件实现方法进行简要介绍。部队应用表明,该测试诊断平台可实现多种通控设备的一体化综合测试与诊断,满足部队野战条件下指挥系统通控设备的测试诊断需求。     

Preparation and analytical electron microscopy of a SiC continuous-fiber ceramic composite

Continuous-fiber-reinforced SiC/SiC-based matrix composite materials, to be used in the first-wall blanket of a fusion reactor, were prepared by the infiltration of SiC cloth with SiC-based suspensions of various chemical compositions. The compositions were tailored with respect to the calculated activation in a fast-neutron flux. Liquid-phase sintering was used for material densification, using different sintering aids, such as Al₂O₃, Y₂O₃, P₂O₅, AlN, etc. The microstructures of the differently prepared materials were studied with scanning and transmission electron microscopy and microanalysis. This paper was presented at the International Symposium on Manufacturing, Properties, and Applications of Nanocrystalline Materials sponsored by the ASM International Nanotechnology Task Force and TMS Powder Materials Committee on October 18–20, 2004 in Columbus, OH.     

First results of target preparation by the HIVIPP method in pressures higher than one bar

We recently developed a new variation for the deposition method named HIVIPP (HIgh energy VIbrational Powder Plating), which is based on the high-energy vibrational motion of powder in the high electric field between parallel electrodes at room temperature and in vacuum. The HIVIPP method is very simple and does not require any complicated mechanisms to prepare both supported (backed) and self-supporting targets. The motivation for the present work was a desire to explore whether it could be done successfully with pressures higher than one bar, with reactive gases or inert gases, and without a vacuum-pumping system. The first successful results are reported for depositions of metallic chromium and non-metallic silicon powders in nitrogen, oxygen, and air at >1 bar.     

The limitations of associated alpha particle technique for contraband container inspections

Inspection of a shipping container for the presence of the threat materials has been investigated in the laboratory by using a 14 MeV neutron beam, a BaF₂ gamma detector and the associated alpha particle technique. The associated alpha particle technique is proposed as a part of a two sensor system for contraband container inspections. This method is effective in the reduction of background radiation with the possibility of collimating electronically the neutron beam.The intrinsic time resolution has been experimentally estimated to be 1.3 ns (FWHM), which allows inspection of a minimum voxel having 7 cm depth along the neutron flight path. The neutron beam intensity plays a crucial role as a limiting factor for the acquisition time reduction. Single counting rates of the gamma and alpha detector were investigated as a function of the neutron intensity, distance between the gamma detector and the neutron source and the type of shielding. The time and the energy spectra for different neutron intensities were evaluated.     

Hydrogen analysis of mineral samples at University of Tsukuba

This study reports the present status of our work on the hydrogen analysis of mineral and rock samples. The preparation of a standard material by means of ion implantation, a method of its calibration and the application of the method are described. The number of hydrogen atoms per unit volume in the standard material can be determined from the simultaneous observation of -particles, γ rays and –γ coincidence events for the ¹H(¹⁹F,γ) reaction at the 16.44 MeV resonance energy. The hydrogen content in a natural obsidian determined with the method mentioned above is in agreement with that obtained by FTIR. A heavy-ion microbeam system under construction, which consists of a Russian-type quadrupole magnet for beam focusing, a beam defining slit system and a γ-ray detector, is also described.     

Design and performance of capping layers for extreme-ultraviolet multilayer mirrors

Multilayer lifetime has emerged as one of the major issues for the commercialization of extreme-ultraviolet lithography (EUVL). We describe the performance of an oxidation-resistant capping layer of Ru atop multilayers that results in a reflectivity above 69% at 13.2 nm, which is suitable for EUVL projection optics and has been tested with accelerated electron-beam and extreme-ultraviolet (EUV) light in a water-vapor environment. Based on accelerated exposure results, we calculated multilayer lifetimes for all reflective mirrors in a typical commercial EUVL tool and concluded that Ru-capped multilayers have approximately 40x longer lifetimes than Si-capped multilayers, which translates to 3 months to many years, depending on the mirror dose.     

High-temperature stability multilayers for extreme-ultraviolet condenser optics

We investigate the thermal stability of Mo/SiC multilayer coatings at elevated temperatures. Transmission electron microscopy and x-ray diffraction studies show that, upon annealing, a thermally induced structural relaxation occurs that transforms the polycrystalline Mo and amorphous SiC layers in as-deposited multilayers into an amorphous Mo-Si-C alloy and crystalline SiC, respectively. After this relaxation process is complete, the multilayer is stable at temperatures up to 400 degrees C.