程序升温大体积进样和解卷积气相色谱-质谱法测定蔬菜水果中32种农药残留量

建立了蔬菜、水果中有机磷、有机氯、拟除虫菊酯和氨基甲酸酯等32种农药的气相色谱-质谱(GC-MS)检测方法。样品经乙腈提取,石墨碳黑串联丙氨基固相萃取柱净化,采用程序升温大体积进样,GC-MS全扫描模式采集,结合解卷积技术定性分析,内标法定量。分别对程序升温和大体积进样等条件进行了研究,并考察了方法选择性和耐用性。在最优条件下,32种农药的响应值与浓度呈良好的线性关系(r>0.995),各农药的方法检出限为2.0~5.0 μg/kg,以菠菜、四季豆和黄瓜为代表基质,进行3个水平(0.010~0.50 mg/kg)的加标回收试验(n=6),回收率为65.2%~120.3%,相对标准偏差(RSD)为4.1%~22.3%。该方法快速、灵敏、可靠、耐用,能满足蔬菜、水果中多类多残留痕量分析的要求。     

悬浮液进样FAAS测定松口蘑中的锰

悬浮液进样-次灵敏线火焰原子吸收光谱法(FAAS)测定松口蘑中锰的方法。以琼脂为悬浮剂将松口蘑样品均匀、稳定地悬浮于琼脂溶胶中,直接喷入空气-乙炔火焰中,采用锰280.1nm次灵敏线,校准曲线或标准加入法测定,省去了以往繁琐的样品化学前处理过程,解决了高锰样品测定中由于称样量小、稀释倍数过大所引起的分析误差。方法简便、快速。用本法测定松口蘑标准样品,获得满意结果。     

Stochastic Four-State Mechanochemical Model of F1-ATPase

F1-ATPase, a part of ATP synthase, can synthesize and hydrolyze ATP moleculars in which the central γ-subunit rotates inside the α3β3 cylinder. A stochastic four-state mechanochemical coupling model of F1-ATPase is studied with the aid of the master equation. In this model, the ATP hydrolysis and synthesis are dependent on ATP, ADP, and Pi concentrations. The effects of ATP concentration, ADP concentration, and the external torque on the occupation probability of binding-state, the rotation rate and the diffusion coefficient of F1-ATPase are investigated. Moreover, the results from this model are compared with experiments. The mechanochemical mechanism F1-ATPase is qualitatively explained by the model.     

Metallic Contaminant Detection using a High-Temperature Superconducting Quantum Interference Devices Gradiometer

We develop magnetic metallic contaminant detectors using high-temperature superconducting quantum interference devices （HTS-SQUIDs） for industrial products. Finding ultra-small metallic contaminants is an important issue for manufacturers producing commercial products such as lithium ion batteries. If such contaminants cause damages, the manufacturer of the product suffers a big financial loss due to having to recall the faulty products. Previously, we described a system for finding such ultra-smafi particles in food. In this study, we describe further developments of the system, for the reduction of the effect of the remnant field of the products, and we test the parallel magnetization of the products to generate the remnant field only at both ends of the products. In addition, we use an SQUID gradiometer in place of the magnetometer to reduce the edge effect by measuring the magnetic field gradient. We test the performances of the system and find that tiny iron particles as small as 50 × 50 μm^2 on the electrode of a lithium ion battery could be clearly detected. This detection level is difficult to achieve when using other methods.     

Theoretical Design of a 104MHz Ladder Type IH-RFQ Accelerator

Beam dynamics and rf designs of a 104 MHz ladder type IH-RFQ （L-IH-RFQ） accelerator are finished at Peking University for the acceleration of 14C＋ from 40 keV to 500 keV. As a specific feature, the output beam energy spread is as low as 0.6% achieved with the internal discrete bunching method, which makes potential applications of RFQ feasible, such as accelerator mass spectrometry and ion implantation. Tolerances of the beam dynamics design are studied by means of changing the input beam parameters, and the results are quite satisfying. On the other hand, the L-IH-RFQ structure is employed, taking advantage of its mechanical stability and the absence of inter-electrode voltage asymmetry. Radio-frequency properties are studied and optimized for reducing power loss with Microwave Studio （MWS）. Tuning of the field flatness and frequency is investigated in principle.     

机械产品基于变更影响和升级复杂度的升级潜力评估

基于信息熵理论和产品结构关联性研究, 提出了一个机械产品升级潜力评估模型, 从升级变更影响程度(前端)和升级复杂度(后端)两方面进行综合分析, 得出机械产品的升级潜力量化值, 并用实例验证了所提出模型的有效性.     

高性能电解水电极催化材料的设计及产品工程

随着市场竞争的加剧,以产品需求为导向精确定制符合需求的化学品成为化学工程研究发展的探索新方向。电解水制氢是生产高纯氢气并转换储存大规模可再生能源的一种有效方法。为实现高效的电-氢气转换效率,高性能的电解水析氢析氧电极是必不可少的。电解水电极材料具有复杂的化学组成及多层次的结构,其中电极表面催化材料的物理化学性质和形貌结构是决定电解水性能的最主要因素。本文结合本课题组在电解水催化方面的研究工作,综述了近几年国内外电解水电极催化材料的最新研究进展,阐述了电解水电极催化材料以反应机理为导向的催化剂设计理论、以产品性能为导向的催化剂设计方法学（包括纳米结构构筑、晶面调控、载体复合、晶相调节、杂原子掺杂、合金化和聚合物表面修饰）及应用,针对化学产品工程的发展与需要,介绍了电解水电极催化材料跨越分子尺度、微纳结构及合成应用的产品设计和产品工程研究的关键科学问题和发展方向。     

全帧型CCD数码相机曝光时间的精确控制

提出一种全帧型CCD数码相机曝光控制方案.在测量机械快门机械延时的基础上,控制CCD触发脉冲TRG和机械快门的控制时序,使得带电子快门的CCD相机,在机械快门的配合下,CCD的感光区都能按各种设计要求的曝光时间精确曝光,从而有效的提高了照片的分辨率.该方法设计简单,不需要额外的硬件电路,可以广泛应用于带机械快门的CCD数码相机曝光时间的精确控制中.     

产品追溯中基于多企业合作模式的制造过程编码研究

通过对多企业合作模式下制造过程编码的需求和信息要素分析, 以产品制造信息追溯为目的, 基于层级分类思路, 提出了类—级—层的编码结构模型, 制定了编码规则及编码属性, 并以QR Code二维码的形式进行表达, 支持产品的信息追溯.     

Al2TiO5/Al2O3陶瓷复合材料的晶粒异向生长

通过机械激活法制备了Al2TiO5/Al2O3(nAl2TiO5: nAl2O3=1: 4)的陶瓷复合材料.利用X射线衍射(XRD)、扫描电镜(SEM)以及能谱(EDS)分析了不同的温度制度下Al2TiO5/Al2O3陶瓷复合材料的晶粒生长特性.X射线衍射谱图(XRD)显示烧结样品的主晶相为α-Al2O3和Al2TiO5.SEM和EDS分析显示,较低温度下烧结(1350 ℃)时Al2TiO5晶粒为等轴状.当温度升高到1450 ℃时,Al2TiO5开始异向长大,形成棒状晶粒.随着温度的升高(1500 ℃),棒状Al2TiO5的长径比继续增加.而Al2O3则始终为片状和等轴晶粒,且异向生长的Al2TiO5晶粒填充于Al2O3三角晶界处.研究表明,烧结温度的升高会促进晶体异向生长并增加其体积分数.Al2TiO5会阻碍Al2O3基体颗粒进一步生长,所以当Al2TiO5颗粒平均尺寸随着烧结温度增加而增大,Al2O3基体晶粒生长几乎停滞.