离子色谱法测定饮用水中的5种卤代乙酸

利用IonPac AS19大容量阴离子交换色谱柱对水中的一氯乙酸、二氯乙酸、三氯乙酸、一溴乙酸、二溴乙酸5种卤代乙酸(HAAs)进行了分离,优化了分离条件.通过控制分离温度实现了二氯乙酸(DCAA)与NO2-的分离;通过梯度洗脱使三氯乙酸(TCAA)与SO42-得到较好、较快的分离;通过中和脱气法解决了在大量CO32-(HCO3-)存在时对实验的干扰.DCAA、TCAA的检出限(以3倍信噪比计)分别达到了2.50 μg/L和3.75 μg/L.5种HAAs在10.0～2 000.0 μg/L线性范围内线性相关系数在0.999以上.     

高钙镁铅锌矿中锌的交流示波极谱滴定

本文阐述了用交流示波极谱滴定法测定高钙镁铅锌矿中的锌。在NH_4Cl—NH_3H_2O(pH=10)支持电解质中采用微银汞膜电极进行实验。分别用NH_4F和铜试剂掩蔽钙、镁、铜、铅、镉及其它竽金属元素。铁和铝不干扰测定。用EDTA滴定锌获得令人满意的结果,对两种矿样分析,准标偏差为0.05%和0.07%。该法快速准确,适用于测定高钙镁的铅锌矿中锌。     

Numerical simulation of liquid crystalline polymer flow into two‐dimensional thin cavity moulds

In this paper, flows of liquid crystalline polymers into two‐dimensional thin cavity moulds are simulated. The flows are modelled by Ericksen–Leslie equations of motion in the high viscosity limit. An elliptic pressure equation is derived under Hele–Shaw approximations, and the non‐isothermal natures of the flow are modelled. The equations are solved using the finite‐difference technique. A new boundary‐mapping technique is developed in this study to solve the difficulty in the finite‐difference treatment of arbitrarily shaped boundaries, which possess no natural coordinate system. This new method avoids the difficult mesh control in the body‐fitted mapping process and makes the mapping process easy to implement. It can also solve the problems caused by the uneven distribution of grid nodes in the traditional body‐fitted mapping technique. Copyright © 2008 John Wiley & Sons, Ltd.     

Enhancing consensus in weighted networks with coupling time-delay

We study the consensus problem in a weighted and directed network composed of self-propelled agents. The weight which quantifies the relationship between the agents is adjusted according to their state incoherence to suppress the heterogeneity in state. The proposed consensus protocol enhances the convergence efficiency of consensus greatly and has better performance than that of two other protocols. The convergence efficiency can be further improved by adjusting the parameter of this protocol. Furthermore, the robustness of the system against coupling time-delay is significantly increased. Unlike most consensus acceleration methods, no topological information is needed in our model. Networks with different stuctures are investigated to demonstrate the generality of the method.     

磷酸铁锂正极材料的缺陷机理与改性技术路径

磷酸铁锂(LiFePO₄,简称LFP)因其良好的安全性、稳定的充放电平台和原料来源广泛等优点,成为当前应用最广泛的正极材料之一。然而,LFP倍率性能较差,且在低温环境下容量大幅衰减,限制了其在动力电池和特殊环境下的应用。本文从多角度分析了LFP存在缺陷的机理,并总结了几种主要的改性技术路径及作用原理。最后,对LFP未来的发展方向提出了相应的展望。     

Quantitative analysis of multicomponents by single marker combined with HPLC fingerprint qualitative analyses for comprehensive evaluation of Aurantii Fructus

The present study aimed to develop a strategy involving quantitative analysis of multicomponents by single marker in combination with high‐performance liquid chromatography fingerprint qualitative analysis for performing the quality control of Aurantii Fructus. The content of 12 components (eriocitrin, neoeriocitrin, narirutin, naringin, hesperidin, neohesperidin, meranzin, poncirin, naringenin, nobiletin, tangeretin, and auraptene) in samples was determined using reliable relative correction factors that were obtained using naringin as an internal reference standard. The new method demonstrated good applicability, and no significant differences were observed between the external standard method and the new method as determined by calculating standard method difference. Qualitative evaluation of samples was conducted using similarity analysis, hierarchical cluster analysis, and quality fluctuation analysis. Chromatographic fingerprint data were divided into three groups by similarity and hierarchical cluster analyses, and seven components may have a more significant impact on the quality of Aurantii Fructus in quality fluctuation analysis. Overall, the study suggests that the qualitative and quantitative analyses of multicomponents using quantitative analysis of multicomponents by single marker combined with chromatographic fingerprinting can be considered good quality criteria for performing quality control and providing technical support for the further pharmacological and pharmaceutical research of Aurantii Fructus.     

Openwork@Dendritic Mesoporous Silica Nanoparticles for Lactate Depletion and Tumor Microenvironment Regulation

The direct depletion of lactate accumulated in the tumor microenvironment holds promise for cancer therapy but remains challenging. Herein, we report a one-pot synthesis of openwork@ dendritic mesoporous silica nanoparticles (ODMSNs) to address this problem. ODMSNs self-assembled through a time-resolved lamellar growth mechanism feature an openworked core and a dendritic shell, both constructed by silica nanosheets of ≈3 nm. With a large pore size, high surface area and pore volume, ODMSNs exhibited a high loading capacity (>0.7 g g⁻¹) of lactate oxidase (LOX) and enabled intratumoral lactate depletion by >99.9 %, leading to anti-angiogenesis, down-regulation of vascular endothelial growth factor, and increased tumor hypoxia. The latter event facilitates the activation of a co-delivered prodrug for enhancing anti-tumor and anti-metastasis efficacy. This study provides an innovative nano-delivery system and demonstrates the first example of direct lactate-depletion-enabled chemotherapy.     

人才招聘的优化模型

人力资源是企业最重要的资源,一个企业如果能适时、适质、适量的获得所需要的人才,并使其在合适的岗位上创造良好绩效,就能在竞争激烈的环境中立于不败之地.本文通过建立人才招聘优化模型来为企业更合理、更科学招聘人才提供服务.