应用于汽车修补的水性双组分聚氨酯涂料

回顾了汽车修补漆的历史,重点对应用于汽车修补漆的水性双组分聚氨酯涂料进行了综述,介绍了各种含羟基组分和异氰酸酯组分的组成、合成方法及其性能指标,指出该类涂料是一种非常具有发展前景的汽车修补漆。     

Preparation of Polymer Microparticles through Nonaqueous Suspension Polycondensations: Part V—Modeling and Parameter Estimation for Poly(butylene succinate) Polycondensations

Polycondensation polymers are normally produced through bulk and solution polymerization processes, which are characterized by significant mass and heat transfer constraints and difficult polymer purification (when prepared in solution). Therefore, it is desirable to develop industrial processes that can circumvent some of these limitations. Recently, a suspension polycondensation process has been developed, rendering the industrial process simpler and enabling the manufacture of polycondensation polymer microparticles. For this reason, the present work builds a phenomenological model to describe the analyzed suspension polycondensation reactions and estimate the model parameters required to simulate poly(butylene succinate) suspension polycondensations. It is shown that both the suspending medium and the reaction conditions can affect the mass transfer resistance for removal of water and that mass transfer rate coefficients are controlled mainly by reaction temperature and solubility of water in the suspending medium, leading to higher mass transfer rates when polymerizations are carried out in soybean oil (when compared to paraffin) at higher temperatures.     

DFT和热力学研究氢键协同效应及对关联1H NMR的影响

用DFT方法在B3LYP／6—311 G(d,p)水平下研究了甲醇线性和环状分子簇．对于不同大小的分子簇之间定义了协同因子,计算得到的协同因子可以验证氢键的强协同效应,环状分子簇之间的协同效应远远大于线性分子簇,做为理论验证和比较,热力学模型分别采用含氢键缔合的格子流体状态方程(LFHB),以及含氢键协同效应的LFHB,关联醇一惰性体系的^1H核磁共振化学位移．考虑协同效应的关联结果优于原始的LFHB,比较量子化学计算的和热力学模型中采用的协同因子,认为甲醇和乙醇在溶液中更可能大部分以线性缔合形式存在。     

人工神经网络预测非环状亚硝胺急性毒性的QSAR研究

在DFT-B3LYP/6-311+G(d,p)水平对60种非环状亚硝胺分子结构进行几何全优化,通过多元逐步线性回归(MSR)分析筛选出9个量子化学描述符作为自变量,log LD50(lethal dose 50％,LD50:大鼠口服急性毒性)作为因变量,采用人工神经网络(ANN)方法构建QSAR模型.经Levenber...     

保健食品中违禁药物检验技术研究进展

保健食品是适用于特定人群、具有调节作用、不以治疗疾病为目的的食品。随着人们生活水平的提高和对健康的追求，保健食品市场日益增大。目前，制售假冒伪劣保健产品、虚假宣传保健食品功效和欺诈式销售产品是制约保健食品产业可持续发展的主要因素。尤其是保健食品中违禁药物的非法添加，使保健食品的食用安全存在较大隐患，严重降低消费者的信心。对保健食品违禁添加的药物进行有效监管，对保护消费者权益具有十分重要的意义。该综述以与保健功能声称相关的药物药理作用为溯源基础，系统梳理了保健食品中可能非法添加的违禁药物种类，重点介绍常见的8类保健食品违禁药物检测技术进展，包括液相色谱法、液相色谱-质谱法、直接实时分析质谱法、气相色谱-质谱法、核磁共振波谱法、红外光谱法、高分辨质谱法等，以期为保健食品违禁药物检测标准的研制和日常监测提供参考，同时对保健食品中违禁药物添加的趋势和检验技术发展进行了简单展望。     

Immunoassay by detecting enhanced resonance light scattering signals of immunocomplex using a common spectrofluorometer

A sensitive, highly specific immunoassay method has been developed by measuring the enhanced resonance light scattering (RLS) signals of immunoreactions with simultaneously scanning both the excitation and the emission monochromators of a common spectrofluorometer. For a given content of antibody (Ab), the RLS signals of an immunoreaction follow Gaussian distribution with antigen (Ag) concentration. The central position of the Gaussian curve represents the concentration of given Ab, and the half bandwidth has proved to be a characteristic constant of a given Ab-Ag immunoreaction. With the RLS signals, the limit of detection for human immunoglobulin G (HIgG) in serum samples could reach 10 ng ml⁻¹, and the concentration of HIgG in blood serum samples could be detected with the recovery of 90.2-107.7% and R.S.D. of 0.8-2.7%. The results of determination for three human serum samples are identical to those obtained by immunoturbidimetry.     

微流控芯片系统在循环肿瘤细胞分离检测中的应用进展

循环肿瘤细胞(CTCs)的分离分析一直是肿瘤相关研究中的热点方向,作为液体活检的重要标志物之一,其在外周血中的含量与癌症病发状况密切相关.然而人体血液中CTCs的含量非常低,通常来说仅有0～10个/mL,因此在开展临床血液样本中CTCs的检测前,往往需要对样本进行前处理,以实现CTCs的分离和富集.微流控芯片技术凭借样...     

Determination of lipid content and stability in lipid nanoparticles using ultra high-performance liquid chromatography in combination with a Corona Charged Aerosol Detector

For many years, lipid nanoparticles (LNPs) have been used as delivery vehicles for various payloads (especially various oligonucleotides and mRNA), finding numerous applications in drug and vaccine development. LNP stability and bilayer fluidity are determined by the identities and the amounts of the various lipids employed in the formulation and LNP efficacy is determined in large part by the lipid composition which usually contains a cationic lipid, a PEG-lipid conjugate, cholesterol, and a zwitterionic helper phospholipid. Analytical methods developed for LNP characterization must be able to determine not only the identity and content of each individual lipid component (i.e., the parent lipids), but also the associated impurities and degradants. In this work, we describe an efficient and sensitive reversed-phase chromatographic method with charged aerosol detection (CAD) suitable for this purpose. Sample preparation diluent and mobile phase pH conditions are critical and have been optimized for the lipids of interest. This method was validated for its linearity, accuracy, precision, and specificity for lipid analysis to support process and formulation development for new drugs and vaccines.     

Biomimetic polymer/apatite composite scaffolds for mineralized tissue engineering

The material surface must be considered in the design of scaffolds for bone tissue engineering so that it supports bone cells adhesion, proliferation and differentiation. A biomimetic approach has been developed as a 3D surface modification technique to grow partially carbonated hydroxyapatite (the bonelike mineral) in prefabricated, porous, polymer scaffolds using a simulated body fluid in our lab. For the rational design of scaffolding materials and optimization of the biomimetic process, this work focused on various materials and processing parameters in relation to apatite formation on 3D polymer scaffolds. The apatite nucleation and growth in the internal pores of poly(L-lactide) and poly(D,L-lactide) scaffolds were significantly faster than in those of poly(lactide-co-glycolide) scaffolds in simulated body fluids. The apatite distribution was significantly more uniform in the poly(L-lactide) scaffolds than in the poly(lactide-co-glycolide) scaffolds. After incubation in a simulated body fluid for 30 d, the mass of poly(L-lactide) scaffolds increased approximately 40%, whereas the mass of the poly(lactide-co-glycolide) scaffolds increased by about 15% (see Figure). A higher ionic concentration and higher pH value of the simulated body fluid enhanced apatite formation. The effects of surface functional groups on apatite nucleation and growth were found to be more complex in 3D scaffolds than on 2D films. Surprisingly enough, it was found that carboxyl groups significantly reduced the apatite formation, especially on the internal pore surfaces of 3D scaffolds. These findings are critically important in the rational selection of materials and surface design of 3D scaffolds for mineralized tissue engineering and may contribute to the understanding of biomineralization as well.SEM micrograph of a poly(L-lactide) scaffold.     

A GROUND HYDROLOGIC MODEL WITH INCLUSION OF A LAYER OF VEGETATION CANOPY THAT CAN INTERACT WITH GENERAL CIRCULATION MODEL

In this paper, a ground hydrologic model(GHM) is presented in which the vapor, heat and momentum exchanges between ground surface covers (including vegetation canopy) and atmosphere is described more realistically. The model is used to simulate three sets of field data and results from the numerical simulation agree with the field data well. GHM has been tested using input data generated by general circulation model (GCM) runs for both the North American regions and the Chinese regions, The results from GHM are quite different from those of GHMs in GCMs. It shows that a more active concerted effort on the land surface process study to provide a physically realistic GHM for predicting the exchange between land and atmosphere is important and necessary.     

Recent progress in analytical instrumentation for glycemic control in diabetic and critically ill patients

Implementing strict glycemic control can reduce the risk of serious complications in both diabetic and critically ill patients. For this reason, many different analytical, mainly electrochemical and optical sensor approaches for glucose measurements have been developed. Self-monitoring of blood glucose (SMBG) has been recognised as being an indispensable tool for intensive diabetes therapy. Recent progress in analytical instrumentation, allowing submicroliter samples of blood, alternative site testing, reduced test time, autocalibration, and improved precision, is comprehensively described in this review. Continuous blood glucose monitoring techniques and insulin infusion strategies, developmental steps towards the realization of the dream of an artificial pancreas under closed loop control, are presented. Progress in glucose sensing and glycemic control for both patient groups is discussed by assessing recent published literature (up to 2006). The state-of-the-art and trends in analytical techniques (either episodic, intermittent or continuous, minimal-invasive, or noninvasive) detailed in this review will provide researchers, health professionals and the diabetic community with a comprehensive overview of the potential of next-generation instrumentation suited to either short- and long-term implantation or ex vivo measurement in combination with appropriate body interfaces such as microdialysis catheters.     

Development of a liquid chromatography-based screening methodology for proteolytic enzyme activity

A new methodology for the detection and isolation of serine proteases in complex mixtures has been developed. It combines the characterization of crude samples by electrospray tandem mass spectrometry (ESI-MS/MS) in a multi-substrate assay and the differentiated sensitive detection of the responsible enzymes by means of liquid chromatography hyphenated online to biochemical detection (BCD). First, active samples are identified in the multi-substrate assay monitoring the conversion of eight substrates in multiple reaction monitoring in parallel within 60 s. Hereby, the product patterns are investigated and the suitable peptide as substrate for BCD analysis is selected. Subsequently, the active proteases are identified online in the continuous-flow reactor serving as BCD after non-denaturing separation by size-exclusion chromatography and ion-exchange chromatography. For BCD, the selected para-nitroaniline (pNA) labeled peptide is added post-column and is cleaved by eluting proteases under release of the coloured pNA in a reaction coil (reaction time 5 min). The method was optimized and the figures of merit were characterized with trypsin and chymotrypsin serving as the model proteases. For trypsin, a limit of detection in LC–BCD of 0.1 U/mL corresponding to an injected amount of 0.4 ng protein (∼18 fmol) was observed. The BCD signal remained linear for an injected enzyme concentration of 0.3–10 U/mL (1.3–42 ng enzyme). The method was applied to the characterization of the crude venom of the pit viper Bothrops moojeni and the extracellular protease of the pathogenic amoeba Acanthamoeba castellanii. In the two samples, fractions with proteolytic activity potentially interfering with the blood coagulation cascade were identified. The described methodology represents a tool for serine protease screening in complex mixtures by a fast ESI-MS/MS identification of active samples followed by the separation and isolation of active sample constituents in LC–BCD.     

Adsorption of Pentafluorophenol onto Powdered,Granular, and Cloth Activated Carbons

In the present study, the adsorption of pentafluorophenol from aqueous solution onto granular activated carbon, powdered activated carbon, and activated carbon cloth has been investigated from the equilibrium and kinetic points of view. To the best of our knowledge, the removal of pentafluorophenol from aqueous solution onto activated carbon have not been reported in the literature. The experimental equilibrium data, suitably fitted by the Toth, Langmuir-Freundlich, and Redlich-Peterson isotherms, have shown that the cloth and powdered carbons exhibit the highest adsorption capacity. For all the investigated samples, the experimental kinetic data have been satisfactorily interpreted by a pseudo-second-order model. From the fitting results it has been observed that the highest rate constant and initial rate of adsorption is shown by powdered activated carbon.     

Technology of electrochemical impedance spectroscopy for an energy-sustainable society

Electrochemical impedance spectroscopy has been widely used to understand the chemistry and physics of battery systems. This review covers electrochemical impedance spectroscopy used for the interpretation of impedance data of lithium-ion batteries (LIBs) from advanced equivalent circuit models to the mathematical model, which is developed by John Newman. In addition, as a method to realize an energy-sustainable society using diagnostics based on the combination of LIBs and electrochemical impedance spectroscopy, on-board diagnostics of battery packs are achieved based on an input signal generated by a power controller in a battery management system instead of the conventionally used frequency response analyzer. The diagnostic system is applicable to energy management systems which are installed in homes, buildings, and communities, accumulating the impedance data on state of health of LIBs. Finally, a future possibility regarding the diagnostics of battery packs coupled with the machine learning of impedance data is introduced.     

A categorical structure–activity relationship analysis of GPR119 ligands

The categorical structure–activity relationship (cat-SAR) expert system has been successfully used in the analysis of chemical compounds that cause toxicity. Herein we describe the use of this fragment-based approach to model ligands for the G protein-coupled receptor 119 (GPR119). Using compounds that are known GPR119 agonists and compounds that we have confirmed experimentally that are not GPR119 agonists, four distinct cat-SAR models were developed. Using a leave-one-out validation routine, the best GPR119 model had an overall concordance of 99%, a sensitivity of 99%, and a specificity of 100%. Our findings from the in-depth fragment analysis of several known GPR119 agonists were consistent with previously reported GPR119 structure–activity relationship (SAR) analyses. Overall, while our results indicate that we have developed a highly predictive cat-SAR model that can be potentially used to rapidly screen for prospective GPR119 ligands, the applicability domain must be taken into consideration. Moreover, our study demonstrates for the first time that the cat-SAR expert system can be used to model G protein-coupled receptor ligands, many of which are important therapeutic agents.     

A comparison of the pseudo-steady-state and shrinking-core model for the reduction of titanium dioxide to titanium

A multistage shrinking-core model is proposed for the electrodeoxidation of titanium dioxide to titanium. This takes place through a series of steps from TiO₂ to Ti₃O₅ to Ti₂O₃ to TiO to Ti. Ideally, the model would incorporate a number of shells of the above lower oxide phases with the shrinking core of TiO₂ in the center but this would be mathematically intractable. A simpler method would be to use the shrinking-core model for each of the individual reductions. Taking the experimental parameters and diffusion coefficient of oxygen in the different phases into account, an analytical solution is developed for the transient differential equation. The first ten eigenvalues are taken into account for the computation of the series solution. This is then compared with a solution based on a pseudo-steady-state approximation to the transient equations. Based on the results, for higher values (>0.01) of dimensionless applied current density, I _d , both the solutions disagree in terms of the time it takes for the core to shrink completely. The difference appears to be decreasing with lower values of I _d but for larger values of I _d the pseudo-steady-state approximation fails to yield results close to the analytical solution.     

Micellar and microemulsion electrokinetic chromatography of hop bitter acids

The elution order of the hop α- and β-acids has been studied under different modes of electrokinetic separation. A model is advanced to explain the shorter migration times of the more hydrophobic β-acids compared to the α-acids in micellar electrokinetic chromatography (MEKC). For quality control of the bitter principles in hops, the ruggedness of electrokinetic separation could be improved by replacing MEKC by microemulsion electrokinetic chromatography (MEEKC).     

DFT和热力学研究氢键协同效应及对关联1H NMR的影响

用DFT方法在B3LYP/6-311＋＋G (d,p)水平下研究了甲醇线性和环状分子簇. 对于不同大小的分子簇之间定义了协同因子. 计算得到的协同因子可以验证氢键的强协同效应, 环状分子簇之间的协同效应远远大于线性分子簇. 做为理论验证和比较, 热力学模型分别采用含氢键缔合的格子流体状态方程(LFHB), 以及含氢键协同效应的LFHB, 关联醇-惰性体系的¹H核磁共振化学位移. 考虑协同效应的关联结果优于原始的LFHB. 比较量子化学计算的和热力学模型中采用的协同因子, 认为甲醇和乙醇在溶液中更可能大部分以线性缔合形式存在.     

Recent advancement on chromo-fluorogenic sensing of aluminum(III) with Schiff bases

The consumption of non-essential aluminum ion (Al³⁺) at higher concentration from biotic and abiotic sources can cause serious adverse effects to the human body. Therefore, there is bourgeoning need of developing facile analytical methods for the on-site and real-time monitoring of Al³⁺ concentration in various environmental and biological samples. The chromo-fluorogenic based sensors have been widely developed in the recent years to detect and monitor Al³⁺ ion. Among the various types of developed chemical sensors, the Schiff bases proved to have several advantages due to their facile synthesis with high yield, fascinating coordination behavior and easy structural modification. This review was narrated to compile the Schiff bases introduced recently for the sensing of Al³⁺ in various environmental and biological samples. The designing of sensor, sensing mechanisms and other analytical novelties of the developed sensors are discussed.     

基于液相色谱-高分辨质谱的代谢组学技术用于麦卢卡蜂蜜的甄别

采用基于液相色谱-高分辨质谱的代谢组学技术对麦卢卡蜂蜜以及国内主要蜂蜜品种的代谢谱进行全面分析，实现了麦卢卡蜂蜜与其他蜂蜜的区分，建立了偏最小二乘法判别模型，对测试样品能够取得很好的鉴定效果。实验从麦卢卡蜂蜜中筛选出高度表达的3-苯乳酸、甲氧基苯乙酮、二氢麻醉椒苦素、芹菜素等黄酮和肉桂酸类等34种代谢标志物，所构建的标志物组合模型的受试者工作特征曲线下的面积达到了0.99。该文建立的代谢组学方法为麦卢卡蜂蜜的质量控制提供了新的思路。