基于无基底扣除的数据趋势累积谱峰检测算法

谱峰的检测分析在色谱技术研究中具有十分重要的作用,但在色谱数据采集、传输的过程中,不同程度的噪声干扰给谱峰检测带来了极大的困难.目前传统的谱峰检测算法普遍通过基底扣除的方式对谱峰的形态进行预定义,将谱峰分为单峰、重叠峰等多个种类.针对不同种类的谱峰采用不同的检测方法,这就导致了传统的谱峰检测算法具有高复杂度、低自动化程...     

Polymer-surfactant and protein-surfactant interactions

The phase behavior and some physicochemical properties of homopolymers (HP) and hydrophobically modified (HMP) polymers, as well as of polyelectrolytes (PE) and proteins (PR), in the presence of aqueous surfactants, or their mixtures, are discussed. Mixing the above components gives rise to the formation of organized phases, whose properties are controlled by polymer and/or surfactant content, temperature, pH, and ionic strength. Depending on the nature, concentration, and net charge of both solutes, molecular solutions, polymer-surfactant complexes, adsorption onto micelles and vesicles, gels, liquid crystalline phases, and precipitates are observed. Such rich polymorphic behavior is the result of a complex balance between electrostatic, excluded volume, van der Waals, and other contributions to overall system stability. It is also modulated by the molecular details and architecture of both the polymer and the surfactant. Different experimental methods allow investigation of the above systems and getting information on the nature of polymer-surfactant interactions (PSI). Surface adsorption and thermodynamic methods, together with investigation of the phase diagrams, give information on the forces controlling PSI and on the existence of different phases. Conductivity, QELS and viscosity allow estimating the size and shape of polymer-surfactant (protein-surfactant) complexes. Optical microscopy, cryo-TEM, AFM, NMR, fluorescence, and relaxation methods give more information on the above systems. Use of the above mixtures in controlling gelation, surface covering, preparing dielectric layers, and drug release is suggested.     

环境样品中双酚类化合物的固相萃取研究进展

双酚类化合物作为一类内分泌干扰物广泛存在于环境介质中,经过多种途径迁移至人体后,可对人体产生内分泌毒性、细胞毒性、基因毒性、生殖毒性、二噁英毒性和神经毒性,已被加拿大政府风险评估识别为进一步优先控制名录。随着环境领域对双酚类化合物的广泛关注,相关研究工作逐渐向水、沉积物、灰尘和生物样品等多介质开拓。但是,由于不同环境样品在基质复杂性和污染物浓度水平等方面存在显著差异,开发提取效率高、净化选择性好、普适性强、操作简单、高通量的提取和净化方法,有助于实现环境介质中双酚类化合物的高灵敏、批量检测。近年来,新型前处理技术发展迅速,尤其是固相萃取技术,在双酚类化合物提取与净化方面取得了长足的发展,不仅在一定程度上克服了传统提取净化方法存在的耗时、耗力和耗溶剂等不足,而且为新型污染物分析提供了更多的技术支持。该文简述了典型双酚类化合物的理化性质、用途用量和环境危害,重点围绕新型固相萃取吸附剂开发和固相萃取模式转变两个方面,总结了固相萃取在双酚类化合物提取净化方法方面取得的进展。商品化固相萃取产品普适性强,在环境监测领域应用范围较广,适用于双酚类化合物的产品种类有限;新型吸附剂研发聚焦吸附容量(如介孔硅材料、碳纳米材料、金属-有机框架材料、环糊精)和选择性(如分子印迹聚合物和混合模式离子交换聚合物)两个方面,种类多样化可满足不同检测需求;越来越多的高灵敏分析仪器不断推向市场,为适应新的发展形势,固相萃取模式正逐渐向微型化、自动化、简易化等方向发展,如QuEChERS、固相微萃取、磁固相萃取等。     

超声提取-高温燃烧吸收-离子色谱法测定纺织品中可吸附有机卤化物北大核心CSCD

建立了一种对纺织品中可吸附有机卤化物(AOX)的超声提取-高温燃烧吸收-离子色谱定量检测分析新方法。该方法采用超声方式提取纺织品中的AOX,提取液加入活性炭进行振荡吸附,并用酸性硝酸钠溶液对无机卤化物进行去除。采用程序升温的氧化燃烧方式对吸附AOX的活性炭进行裂解、燃烧及气化,其产生的卤化氢等气体随载气进入吸收液并完全转化为无机卤素阴离子,采用离子色谱分离测定,外标法定量。实验优化了超声提取时间、活性炭用量、燃烧气及其流量、燃烧升温程序、吸收液和吸收方式等前处理条件,并对离子色谱的仪器分析条件如色谱柱、柱温及淋洗液流速等进行优化。结果表明,氟、氯、溴、碘4种卤素离子的标准溶液在0.02~10 mg/L范围内呈线性关系,线性相关系数(R^(2))均在0.999以上;AOX测定的方法定量限为0.10~0.50 mg/kg。以棉、毛和涤纶3种不同种类的阴性纺织样品作为样品基质,选取典型的有机卤化物进行加标,在低、中、高3个加标水平下测得AOX的平均回收率为82.3%~98.7%,相对标准偏差(RSD,n=7)为2.0%~5.7%,表明方法具有良好的回收率和精密度。将该方法应用于实际纺织样品的测定,检出了不同含量的AOX,且重复性好。研究建立的方法通过采用活性炭的振荡吸附、程序升温的高温氧化燃烧方式和多孔吸收瓶的二级吸收方法,提高了AOX转化为无机卤素的回收率;同时利用离子色谱仪器选择性好、灵敏度高的特点成功地一次性分离检测4种AOX,且无杂质离子的干扰。该方法简单、准确、可靠,满足国内外法规和标准对纺织品中AOX的限量要求,适用于纺织品中AOX的分析测定。     

基于低共熔溶剂的萃取分离技术及其应用研究进展

随着绿色化学的发展,开发和应用符合绿色化学要求的溶剂和方法备受关注。作为离子液体类似物,低共熔溶剂(deep eutectic solvent, DES)是通过氢键受体(hydrogen bond acceptor, HBA)和氢键供体(hydrogen bond donator, HBD)的氢键作用而形成的一种混合物,具有环境友好、制备简单、成本低、可生物降解等优点,在很多领域均有越来越广泛的应用。DES可以从不同样品中萃取和分离不同的目标化合物,其作为萃取溶剂具有独特的优势,可以获得较高的萃取效率且样品基质对分析过程的影响较小。在分散液液微萃取(dispersive liquid-liquid micro-extraction, DLLME)程序中,DES可以萃取复杂基质中的残留药物、金属离子和生物活性成分;与传统的萃取方法相比,该方法具有对有机试剂需求少,萃取效率更高等明显优势。而且,在DLLME中加入DES作为分散剂,能够加速萃取剂在样品溶液中的扩散,具有小型化、成本低等优点。相比于传统分散剂甲醇、乙腈的高挥发性、易燃性,DES的高稳定性、低毒性使其在绿色化学领域中更具有优势,应用更广。因此,DES与DLLME的结合近年来发展迅速。不仅如此,DES与固相萃取联合应用也具有广泛的应用前景,在与固相萃取小柱和搅拌棒联合应用时,DES可以作为洗脱剂,氢键供体及氢键给体的用量之比是洗脱效率的重要考察因素之一。在与磁性材料联用时,DES能与磁性多壁碳纳米管、磁性氧化石墨烯等纳米复合材料结合,通过氢键、π-π作用力和静电作用力等特异性吸附目标分析物。并且能够参与磁性凝胶和分子印迹聚合物的合成,推动磁性材料向绿色化学的方向发展,进一步拓展DES的应用。作为一类新兴的绿色溶剂,DES在化合物的萃取分离技术方面受到广泛关注,在不同的萃取技术中扮演了不同的角色,并表现出良好的性能,因此逐渐成为绿色化学领域的研究重点。该文整合了DES在萃取分离技术中的研究进展,介绍了DES的制备、性质和分类,对DES在DLLME和固相萃取中的应用进行了总结和归类,并展望了DES在萃取分离技术中的应用前景,为DES未来的应用提供参考。     

低温等离子体在锂离子电池材料中的应用

综合评述了低温等离子体技术的基本原理、 常用方法及其在锂离子电池材料领域中的研究进展, 重点评述了等离子体技术在锂离子电池正极、 负极、 隔膜及固态电解质等重要组分中的材料制备与表面改性方面的主要研究结果和应用优势, 并对其所面临的挑战和未来的应用方向进行了展望.     

History of Adhesives

Adhesives are the diplomats of the polymer world. They exist for the purpose of bringing other materials together; their success is measured by the production cost, properties, and permanence of the assembly. Historically, the starches, protein glues, and natural rubber were supplemented or replaced by phenolics and amino resins for plywood and particleboard; synthetic rubbers for construction, textile bonding, and pressure-sensitives; poly-vinyl acetate for packaging, gypsum board, and the home handy-person's “white glue”; hot melts for bookbinding. Three of the newer families of adhesives are outstanding in performance: the epoxies; the isocyanates and polyurethanes; and the versatile acrylics, including the spectacularly growing cyanoacrylates and anaerobics. They are especially useful for the bonding of metals, synthetic fibers, plastic film, and other “difficult” substrates in product assembly, aerospace, textiles, construction, furniture, film laminates, and pressure-sensitives. Synergism and hybrid functionality are hallmarks of many of the new adhesives. Controlled cross-linking, improved adhesion, and other characteristics are attained through adroit blending of functional groups: vinyl unsaturation, carboxyl, glycidyl, hydroxyl, isocyanate, and methylol amide.     

丝素蛋白纤维及功能化材料的设计与构筑

随着环境污染、资源枯竭和医疗健康等问题的加剧,研发同时满足特定使用性能、安全性及可再生性的新型材料成为当前的发展趋势.而丝素蛋白材料正是以天然蚕丝为基本原材料,经一定的加工和功能化而形成的具有特殊结构、独特性能和广泛应用的生物质材料,近年来在生物医药、生物电子、智能传感等领域展现出巨大的应用潜力.本专论总结了丝素蛋白纤维及功能化材料的最新成果,结合本课题组相关工作,重点阐述了再生丝素蛋白纤维的仿生制备、生物医用支架的构筑与功能化、智能电子材料的设计以及天然多功能蚕丝及其构筑基元制备的研究进展,以期为高性能丝素蛋白材料的设计与构筑提供指导和借鉴.     

我国胶体与界面化学的发展

胶体与界面化学在能源、材料、生物、化学制造和环境科学等领域具有广泛的应用,并渗透到国民经济的各个主要领域中。所涉及到其中的一些重大科学问题,如土壤改良、功能与复合材料、三次采油、人造血浆、药物缓释与定向、润滑和油漆涂料等,与国家安全、能源开发、环境保护和人民生活等方面密切相关,发展胶体与界面化学学科对社会与经济的可持续发展具有重要的意义。本文综述了我国胶体与界面化学学科30年来的研究进展,尤其是近10年所取得的成就,主要包括新型两亲分子有序组合体的设计与构建、界面化学与有序分子膜、胶体与界面化学在微纳米功能材料合成中的应用新进展、胶体与界面化学在生物医药中的研究新进展,以及胶体与界面化学的研究新方法,并对该学科的发展前景与趋势进行了分析。     

Atmospheric aerosols: composition, transformation, climate and health effects

Aerosols are of central importance for atmospheric chemistry and physics, the biosphere, climate, and public health. The airborne solid and liquid particles in the nanometer to micrometer size range influence the energy balance of the Earth, the hydrological cycle, atmospheric circulation, and the abundance of greenhouse and reactive trace gases. Moreover, they play important roles in the reproduction of biological organisms and can cause or enhance diseases. The primary parameters that determine the environmental and health effects of aerosol particles are their concentration, size, structure, and chemical composition. These parameters, however, are spatially and temporally highly variable. The quantification and identification of biological particles and carbonaceous components of fine particulate matter in the air (organic compounds and black or elemental carbon, respectively) represent demanding analytical challenges. This Review outlines the current state of knowledge, major open questions, and research perspectives on the properties and interactions of atmospheric aerosols and their effects on climate and human health.     

Fabrication of open‐porous PCL/PLA tissue engineering scaffolds and the relationship of foaming process,morphology, and mechanical behavior

Tissue engineering scaffolds should provide a suitable porous structure and proper mechanical strength, which is beneficial for the delivery of growth factor and regulation of cells. In this study, the open‐porous polycaprolactone (PCL)/poly (lactic acid) (PLA) tissue engineering scaffolds with suitable porous scale were fabricated using different ratios of PCL/PLA blends. At the same time, the relationship of foaming process, morphology, and mechanical behavior in the optimized batch microcellular foaming process were studied based on the single‐factor experiment method. The porous structures and mechanical strength of the scaffolds were optimized by adjusting foaming parameters, including the temperature, pressure, and CO₂ dissolution time. The results indicated that the foaming parameters influence the cell morphology, further determine the mechanical behavior of PCL/PLA blends. When the PCL content is high, with the increase of temperature and time, the cell diameter and the elastic modulus increased, and the tensile strength and elastic modulus increased with the increase of the average cell size, and decreased as the increase of the cell density. While when the PLA content was high, the cell diameter showed the same trend, and the tensile strength and elastic modulus were higher, and the elongation at break was lower, and tensile strength and elastic modulus decreased with the increase of the average cell size and increased with the increase of cell density. This work successfully fabricated optimized porous PCL/PLA scaffolds with excellent suitable mechanical properties, pore sizes, and high interconnectivity, indicating the effectiveness of modulating the batch foaming process parameters.     

Poly(lactide) stereocomplexes: formation, structure, properties, degradation, and applications

Poly(lactide)s [i.e. poly(lactic acid) (PLA)] and lactide copolymers are biodegradable, compostable, producible from renewable resources, and nontoxic to the human body and the environment. They have been used as biomedical materials for tissue regeneration, matrices for drug delivery systems, and alternatives for commercial polymeric materials to reduce the impact on the environment. Since stereocomplexation or stereocomplex formation between enantiomeric PLA, poly(L-lactide) [i.e. poly(L-lactic acid) (PLLA)] and poly(D-lactide) [i.e. poly(D-lactic acid) (PDLA)] was reported in 1987, numerous studies have been carried out with respect to the formation, structure, properties, degradation, and applications of the PLA stereocomplexes. Stereocomplexation enhances the mechanical properties, the thermal-resistance, and the hydrolysis-resistance of PLA-based materials. These improvements arise from a peculiarly strong interaction between L-lactyl unit sequences and D-lactyl unit sequences, and stereocomplexation opens a new way for the preparation of biomaterials such as hydrogels and particles for drug delivery systems. It was revealed that the crucial parameters affecting stereocomplexation are the mixing ratio and the molecular weight of L-lactyl and D-lactyl unit sequences. On the other hand, PDLA was found to form a stereocomplex with L-configured polypeptides in 2001. This kind of stereocomplexation is called "hetero-stereocomplexation" and differentiated from "homo-stereocomplexation" between L-lactyl and D-lactyl unit sequences. This paper reviews the methods for tracing PLA stereocomplexation, the methods for inducing PLA stereocompelxation, the parameters affecting PLA stereocomplexation, and the structure, properties, degradation, and applications of a variety of stereocomplexed PLA materials.     

Optimization of throughput and desorbent consumption in simulated moving-bed chromatography for paclitaxel purification.

In simulated moving-bed (SMB) applications, throughput and desorbent consumption are two key factors that control process cost. For a given adsorbent volume and product purity requirements, throughput and desorbent consumption depend on desorbent composition, column configuration, column length to diameter ratio, and adsorbent particle size. In this study, these design parameters are systematically examined for paclitaxel purification. The results show that if adsorbent particle size, column dimensions and column configuration are fixed, the higher the product purity required, the lower the throughput. If product purity and yield are fixed, the larger the solute migration speed ratio, the higher the throughput, and the lower the desorbent consumption. If total bed volume and product purities are fixed, the longer the separation zones, the higher the throughput, but the higher the desorbent flow-rate. An intermediate configuration gives the minimum desorbent consumption. If there are no limits on pressure drop or zone flow-rate, the larger the column length to diameter ratio, the smaller the adsorbent particle size, the higher the throughput, and the lower the desorbent consumption. If the maximum zone flow-rate is controlled by the pressure drop limit and not by the standing waves requirement, the longer the columns, the lower the zone flow-rates and the lower the throughput. For 150 microns adsorbent particles and a maximum zone flow-rate of 300 ml/min, a design with optimal throughput and desorbent consumption is found for paclitaxel purification.     

Advances in the chemistry of tetrazoles (review)

The review is devoted to the newest advances in the chemistry of tetrazoles. New data on the electronic structures, crystal structures, and dipole moments are presented successively. The electronic, vibrational, NMR, and mass spectra are discussed. Data on the acid-base properties and tautomerism of tetrazoles are presented. Numerous methods for the preparation of tetrazole and mono- and disubstituted tetrazoles are reported. The chemical properties of tetrazoles, viz., electrophilic substitution at the ring carbon atom, nucleophilic substitution, alkylation, electrophilic and nucleophilic substitution in the side chain, and the effect of oxidizing and reducing agents, are discussed. Reactions that lead to cleavage of the tetrazole ring, viz., acylation and thermolysis, are examined separately. New data on the use of tetrazoles in medicine, biology, agriculture, the manufacture of polymeric materials, etc. are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1326, October, 1981.     

Density functional theory study of the hydrogen bond interaction between lactones, lactams, and methanol

The structure and relative stability of methanol complexes with various cyclic ketones, lactones, lactams, and N-methyl lactams from three- to seven-membered rings have been investigated using the density functional theory method. The geometries, harmonic frequencies, and energies were calculated at the B3LYP/6-311+G(d,p) level. Three stable structures, cis-a, cis-b, and trans, with respect to the ring oxygen (nitrogen) atom, were found to be local minima of the potential energy surface. For lactones and N-methyl lactams, the most stable structure is trans; it is stabilized, as in cyclic ketones, through the conventional hydrogen bond (HB) interaction between the basic carbonyl oxygen and the acidic methanolic hydrogen and an unconventional HB interaction between the methanolic oxygen and the CH hydrogen, in the alpha position of the carbonyl group. For unsubstituted lactams, the cis-a structure, stabilized through a HB interaction between the NH group and the methanol oxygen in addition to the conventional HB interaction, is the most stable. The topological properties of the electron density ratify the existence of conventional (N,O-H. . .O) and unconventional (C-H. . .O) hydrogen bonding. A good correlation was found between the HB distances and the electron density at the HB critical point. The unsubstituted lactams yield more stable complexes with methanol than N-methyl lactams, lactones, and cyclic ketones. In the most stable complexes, both components behave simultaneously as a HB donor and as a HB acceptor.     

外泌体生物分析及其临床应用研究进展

外泌体是具有各种关键生物活性分子(如脂质、 蛋白质和核酸)的细胞外囊泡. 它们可以由所有类型的细胞分泌, 并分布在所有生物流体中, 如血液、 唾液、 汗水和尿液等. 更重要的是, 外泌体可以参与多种生理活动, 包括细胞间通讯、 哺乳动物的繁殖和免疫反应, 并在新陈代谢以及心血管疾病、 神经变性和癌症等疾病的病理进展中起重要作用, 这使其成为备受关注的天然非侵入性生物标记物, 并且被认为是可用于临床诊断和治疗的潜在工具。本文综述了用于检测外泌体的生物传感器的最新发展, 包括荧光、 电化学、 电化学发光、 表面增强拉曼光谱、 比色法和微流控技术等分析方法; 总结了在临床诊断和疾病治疗中外泌体的临床应用; 还讨论了外泌体检测所面临的挑战以及外泌体在临床诊断和疾病治疗等方面的应用潜力.     

Effect of Cr(VI) anions on adsorption and desorption behavior of Cu(II) in the colloidal systems of two authentic variable charge soils

Heavy metals in wastes exist as multiple pollutants. The study of the interactions between multiple pollutants and soils should be of significance in practice. In the present study, the effect of chromate on adsorption and desorption behavior of Cu(II) in two variable charge soils was investigated, with the emphasis on the adsorption and desorption equilibria of Cu(II). The results showed that chromate can affect adsorption and desorption of Cu(II) in the colloidal systems of two variable charge soils. The extent of the effect was related to the initial concentrations of chromate and Cu(II), the system pH, and the nature of the soils. The presence of chromate led to an increase in the adsorption of Cu(II). For example, in the presence of 0.5, 0.8, 1.0, and 1.5 mmol L(-1) of chromate, for the rhodic ferralsol the adsorption of Cu(II) increased by 15.3, 18.0, 19.0, and 20.2%, respectively. For the hyperrhodic ferrasol, the corresponding figures were 11.9, 17.0, 20.3, and 26.1%, respectively. The presence of chromate also caused an increase in the desorption of Cu(II). For instance, in the presence of 0.5, 1.0, and 1.5 mmol L(-1) of chromate, the desorption for the rhodic ferralsol increased by 16.9, 27.5, and 34.1%, respectively. For the hyperrhodic ferralsol, the corresponding figures were 18.1, 35.6, and 51.4%, respectively. The increments of the adsorption and desorption increased with the increase in equilibrium concentration of Cu(II) in the solution. For instance, when the equilibrium concentrations were 0.5, 1.0, 1.5, and 2.0 mmol L(-1), the increments for the rhodic ferralsol were 2.5, 3.2, 3.3, and 3.0 mmol kg(-1), respectively. For the hyperrhodic ferralsol, the corresponding figures were 2.9, 3.5, 4.0, and 4.2 mmol kg(-1), respectively. The effect of chromate for the hyperrhodic ferralsol was greater than that for the rhodic ferralsol. This is caused by the difference in the content of iron oxides for the two soils. The increments of the adsorption and the desorption of Cu(II) increased with the rise in pH, reaching a maximum value, and then decreased. It can be assumed that the increment of the adsorption was caused by the change in surface charge of the soils induced by the adsorption of chromate and the cooperative adsorption of chromate adsorbed and Cu(II). The increase of electrostatically adsorbed Cu(II) was responsible for the increase in the desorption of Cu(II).     

A database of lipid phase transition temperatures and enthalpy changes

The systematic study of the mesomorphic phase properties of synthetic and biologically derived lipids began some 30 years ago. In the past decade, interest in this area has grown enormously. As a result, there exists a wealth of information on lipid phase behavior, but unfortunately, these data have, until now, been scattered throughout the literature in a variety of books, proceedings, and journals. The data have recently been compiled in a centralized database with a view to providing ready access to the same and to the appropriate literature. The compilation facilitates review of what has thus far been accomplished and highlights what remains to be done in this active research area. As such, it represents a convenient summary of the existing data which, when evaluated, will enable us to identify where deficits exist in the data, to reveal the fundamental physicochemical principles upon which lipid phase behavior is based, and to understand more completely lipid phase relations in biological, reconstituted, and formulated systems. The compilation consists of a tabulation of all known mesomorphic and polymorphic phase transition temperatures and enthalpy changes for synthetic and biologically derived lipids in the dry and in the partially and fully hydrated states. Also included is the effect on these thermodynamic values of pH, and of salt and metal ion concentration and other additives such as proteins, drugs, etc. The methods used in making the measurements and the experimental conditions are reported. Bibliographic information includes complete literature referencing and list of authors. As of this writing, the database is current through June 1990 and contains 9500 records. Each record contains 28 fields. Here, we describe how the database originated, its scope and contents, data abstraction procedures, and issues relating to mesophase and lipid nomenclature, data analysis, and evaluation, and database maintenance and distribution.