基于程序升温法保留时间预测的气-质联用系统构建虚拟实验室

在气-质联用技术的理论研究及实验的基础上,采用Flash 8.0和ActionScript 2.0编程技术构建开放式网络气-质联用系统虚拟实验室。以若干有机物为考察对象,根据程序升温色谱法(PTGC)中保留值与温度及流速的关系,构建了不同色谱分析条件下保留参数的预测模型,同时利用Flash组件技术,构建与虚拟实验配套的气-质联用系统虚拟工作站。     

三元硝酸熔盐高温粘度的计算

三元硝酸熔盐是一种重要的传热蓄热介质,粘度物性数据对其在工业中应用非常重要.但是由于硝酸熔盐熔点高,腐蚀性强,测试条件苛刻,粘度测量结果偏差较大,故利用计算方法确定熔盐粘度.本文首先通过大量实验数据拟合了纯物质KNO3,NaNO3和NaNO2的粘度,再利用Arrhenius混合规则确定的经验公式计算三元硝酸熔盐的粘度.与前人实际测量值进行比较.结果发现:利用简单经验公式估算的结果与实际测量值比较接近,表明这种熔盐热物性变化受外界影响较小,可以利用Arrhenius简单混合规则确定熔盐粘度.     

Molecular simulation of phase coexistence: Finite-size effects and determination of critical parameters for two- and three-dimensional Lennard-Jones fluids

Abstact The subject of this paper is the investigation of finite-size effects and the determination of critical parameters for a class of truncated Lennard-Jones potentials. Despite significant recent progress in our ability to model phase equilibria in multicomponent mixtures from direct molecular simulations, the accurate determination of critical parameters remains a difficult problem. Gibbs ensemble Monte Carlo simulations with systems of controlled linear system size are used to obtain the phase behavior in the near-critical region for two- and three dimensional Lennard-Jones fluids with reduced cutoff radii of 3, 3.5, and 5. For the two-dimensional systems, crossover of the effective exponent for the width of the coexistence curve from mean field ( = 1/2 in the immediate vicinity of the critical point to Ising-like (= 1/8) farther away is observed. Critical parameters determined by fitting the data that follow Ising-like behavior are in good agreement with literature values obtained with finite-size scaling methods. For the three-dimensional systems, no crossover to mean field-type behavior was apparent. Extrapolated results for the critical parameters are consistent with literature estimates for similar fluids. For both two- and three-dimensional fluids, system size effects on the coexistence curves away from the critical point are small, normally within simulation statistical uncertainties.Invited paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder. Colorado, U.S.A.     

Shape design of cerium oxide nanoparticles for enhancement of enzyme mimetic activity in therapeutic applications

Cerium oxide nanoparticles (CONPs), widely used in catalytic applications owing to their robust redox reaction, are now being considered in therapeutic applications based on their enzyme mimetic properties such as catalase and super oxide dismutase (SOD) mimetic activities. In therapeutic applications, the emerging demand for CONPs with low cytotoxicity, high cost efficiency, and high enzyme mimetic capability necessitates the exploration of alternative synthesis and effective material design. This study presents a room temperature aqueous synthesis for low-cost production of shape-selective CONPs without potentially harmful organic substances, and additionally, investigates cell viability and catalase and SOD mimetic activities. This synthesis, at room temperature, produced CONPs with particular planes: {111}/{100} nanopolyhedra, {100} nano/submicron cubes, and {111}/{100} nanorods that grew in [110] longitudinal direction. Enzymatic activity assays indicated that nanopolyhedra with a high concentration of Ce⁴⁺ ions promoted catalase mimetic activity, while nanocubes and nanorods with high Ce³⁺ ion concentrations enhanced SOD mimetic activity. This is the first study indicating that shape and facet configuration design of CONPs, coupled with the retention of dominant, specific Ce valence states, potentiates enzyme mimetic activities. These findings may be utilized for CONP design aimed at enhancing enzyme mimetic activities in therapeutic applications.

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液氦温区大型低温制冷系统的可靠性评估

针对改进Claude循环的大型氦低温制冷系统,以制冷量不足为顶事件建立了故障树模型。利用结构法对故障树模型进行定性分析,分析得到系统的最小割集为18个。利用来自不同数据库的部件失效率对故障树模型进行定量计算,得到了不同的结果,并分析其原因。对各部件的关键重要度进行了计算,以衡量各个部件对系统发生故障的贡献程度。并通过增加系统冗余部件和提高关键部件可靠度等措施,为提高系统可靠性找到了有效的解决途径。     

Surface energy-mediated fibronectin adsorption and osteoblast responses on nanostructured diamond

Nanostructured diamond have potential applications in many biomedical related fields and demonstrated extraordinary capacity to influence cellular responses. Studying the surface property of nanodiamond and its influence to protein adsorption and subsequent cellular responses along with the mechanism behind such capacity becomes more important. Here the role of surface energy associated with nanostructured diamond in modulating fibronectin and osteoblast(OB, bone forming cells) responses was investigated. Nanocrystalline diamond(NCD) and submicron crystalline diamond(SMCD) films with controllable surface energy were prepared by microwave-enhanced plasma chemical vapor deposition(MPCVD) techniques. Fibronectin adsorption on the diamond films with varied surface energy values was measured via the enzyme-linked immunosorbent assay(ELISA) and the relationship between the surface energy and fibronectin adsorption was studied. The result indicated that fibronectin adsorption on nanostructured surfaces was closely related to both surface energy and material microstructures. The spreading and migration of OB aggregates(each containing 30–50 cells) on the NCD with varied surface energy values were also studied. The result indicates a correlation between the cell spreading and migration on nanodiamond and the surface energy of nanostructured surface.     

用BASIC单片机实现油品密度的测量

油品的密度与温度有着确定的对应关系,通过测量温度可以间接测量密度。根据这一关系可以利用小巧的ＢＡＳＩＣ单片机设计一个价廉、实用的密度计。经实验对比,其稳定性较好,反应灵敏,测量较准确,较常规方法更方便快捷     

渗碳钢变温渗碳过程分析

以２０ＣｒＭｎＴｉ钢为例,建立了连续冷却渗碳模型;对变温渗碳质量进行了分析计算;对渗碳后的组织情况进行预测,从而对变温渗碳的可行性进行了理论论证．     

浅析40T支架搬运车液压系统油温变化对其效率的影响

介绍了油温变化对40T支架搬运车液压系统油液黏度、液压介质和橡胶类密封件的影响,分析了液压系统的总发热功率、总散热功率,结合动态热平衡的计算,找出了液压系统总效率与油温变化之间的关系,并给出其函数关系式。根据这种关系,通过一种工况的油温实测数据取样,计算出相应的效率值,定量地验证了液压系统油温变化引起效率变化的关系,得出了总效率随着温度变化而变化的结论,即温差增大时,总效率降低;温差减小时,总效率增大。通过该结论可以全面掌握系统的工作状态,通过降低油温有效提高效率。     

Development of high throughput microfluidic cell culture chip for perfusion 3-dimensional cell culture-based chemosensitivity assay

This study reports a microfluidic cell culture chip encompassing 36 microbioreactors for high throughput perfusion 3-dimensional (3D) cell culture-based chemosensitivity assays. Its advantages include the capability for multiplexed medium delivery, and the function for both efficient and high throughput micro-scale 3D culture construct preparation and loading. The results showed that the proposed medium pumping mechanism was able to provide a uniform pumping rates ranging from 1.2 to 3.9 μl h⁻¹. In addition, the simple cell/hydrogel loading scheme has been proven to be able to carry out 3D cell culture construct preparation and loading precisely and efficiently. Furthermore, a chemosensitivity assay was successfully demonstrated using the proposed cell culture chip. The results obtained were also compared with the same evaluation based on a conventional 2D monolayer cell culture. It can be concluded that the choice of cell culture format can result in different chemosensitivity evaluation results. Overall, because of the nature of miniaturized perfusion 3D cell culture, the cell culture chip not only can provide stable, well-defined and more biologically relevant culture environments, but it also features low consumption of research resources. All these traits are found particularly useful for high-precision and high-throughput 3D cell culture-based assays.