Contributions to the Chemistry of the Binary Compounds of the Transition Elements

Phase and structural relationships of the sulfur, selenium, and tellurium compounds of the 4d and 5d transition elements of groups IV to VII of the periodic system are discussed. Homologous elements behave very similarly with respect to the chalcogens, and this is particularly the case for niobium and tantalum, and for molybdenum and tungsten. However, zirconium, niobium, and molybdenum have a greater tendency towards formation of chalcogen-poor phases than their homologues hafnium, tantalum, and tungsten. Subchalcogenides are known only for zirconium and niobium. The number of phases and the tendency towards formation of solid solutions are considerably smaller among the tellurides than among the sulfides and selenides. The crystal structures of the telluride phases also differ from those of the sulfide and selenide phases of analogous composition. In addition, a review of the phase and structural relationships of the arsenic and antimony compounds of the 4d and 5d transition elements of groups V to VII is given.     

An integrated strategy of secondary metabolomics and glycomics to investigate multi-component variations in wine-processing of medicinal herbs and functional foods: A case study on Fructus Corni

Fructus Corni (FC), as a promising Chinese medicinal herb, has aroused considerable interest. Generally, FC needs to be processed according to the limited standard policy in China before clinical application, while the investigations on the specific processing methods (such as wine steaming or high-pressure wine steaming) are unclear. A comprehensive metabolomics strategy based on integrated non-targeted metabolomics and targeted glycomics in this paper was implemented to investigate the influences of the different processing technologies such as steaming, wine steaming, high-pressure steaming, high-pressure wine steaming, wine immersion, and wine stir-frying on FC, respectively. UHPLC-Q-TOF-MS/MS was employed for identifying and distinguishing the secondary metabolites. A total of 85 components were identified in all groups. The results of PCA score plots showed that the crude and processed samples had a complete separation, and wine steamed and high-pressure wine steamed samples could be a category, indicating that the two processed products had a similar quality. Multiple chromatography including HPLC (C₁₈)-PDA, HPLC (NH₂)-ELSD, and HPGPC-ELSD was used for determining the molecular weight distributions, the monosaccharide compositions of polysaccharides, and the contents of free monosaccharides and oligosaccharides. The results indicated that the content and composition of saccharides were different in crude and different processed FC. The polysaccharides were composed of fucose, arabinose, galactose, glucose, galacturonic acid, mannose and rhamnose, and the free monosaccharides were composed of fucose, arabinose, galactose, glucose, mannose, rhamnose and fructose in all FC samples. The PCA score plots of the glycomics indicated that the crude and high-pressure wine steamed FC could be a category, showing that the two groups had similar chemical compositions. Ultimately, the simulation processing experiments indicated that the transformation of morroniside, polysaccharides, oligosaccharides, fructose, and glucose to 5-HMF through the reactions of dehydration and deglycosylation was the potential mechanism of enhancing the effects by processing. Conclusionly, the saccharides should be investigated as thoroughly as the secondary metabolites, and the high-pressure wine steamed FC could be an alternative to wine steamed FC.     

纳米粒子的精准组装

纳米材料由于其独特的光、电、磁、力学等性质,成为了构建功能材料与器件的理想基元。实现纳米粒子的精确组装,是探究粒子之间的耦合聚集性质和制备宏观功能器件的基础。但是由于纳米粒子的小尺寸以及在溶液中运动的随机性与复杂性,精准控制纳米粒子组装体的形貌以及在空间中的相对位置仍存在巨大挑战。为了将纳米粒子组装成理想的有序结构,许多控制粒子组装的策略与方法得到发展。本文首先概述了纳米粒子自组装的控制方法与典型形貌,着重分析了影响粒子精准排布的因素与控制方法,并对纳米粒子及其组装体的光学性质与器件应用的最新研究进展进行了讨论,最后对目前纳米粒子精准组装所面临的挑战以及未来发展的方向进行了展望。     

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.     

A review on elastic graphene aerogels: Design,preparation, and applications

Graphene aerogels with unique properties, such as ultralow density, super-elasticity, high specific surface area, and excellent thermal stability, have undergone great progress in the past decades. Especially, super-elastic graphene aerogels provide a highly attention-catching platform for developing advanced energy devices, pressure sensors, contaminates adsorbents, and electromagnetic wave shielding and absorption materials, and so forth. In this review, we begin with the introduction and discussion of various fabrication techniques and compare their advantages and disadvantages, focusing on the template-free assembly process and template-assisted assembly process. Then, we summarize the factors influencing the compressibility and elasticity of graphene aerogels, including intrinsic properties of building blocks, constituent materials, and structure design, and their wide applications. At the end, we discuss the current challenges and future prospects of this field.     

纳米粒子与细胞相互作用的力学-化学偶联研究进展

纳米粒子在生物医学和大气环境领域的广泛研究使得其生物安全性越来越受到重视。目前已经有许多研究关注纳米粒子与细胞的相互作用及细胞毒性问题。本综述从细胞力学-化学偶联的角度总结了近五年来有关纳米粒子与细胞相互作用的研究进展。首先介绍了与细胞力学-化学偶联性质相关的分子基础以及目前检测细胞机械性质的纳米技术,然后重点讨论了纳米粒子对细胞粘附、骨架、刚度和迁移性质的影响。在此基础上,进一步指出了纳米生物力学-化学偶联的挑战与展望。     

1,x-elimination reactions: extending the limits of a classical organic reaction

Alpha,omega-dibromo derivatives in which the two terminal carbon atom are separated by an unsaturated spacer unit ("pi spacer") undergo 1,x-elimination reactions (with x=6, 8, 10, and 14), using Mori's reagent (nBu3SnSiMe3/CsF). The resulting cumulenic intermediates cyclodimerize in a subsequent step yielding novel macrocyclic acetylenic and bridged aromatic compounds (cyclophanes). Thus 1,6-eliminations were carried out with dibromide 17 to yield 1,3,7,9-cyclododecatetrayne (20) and with benzylbromide 24 to provide cyclophanes 26 and 27. By 1,8-eliminations the 16-membered macrocycle 33 could be prepared from enediyne 31, the benzannelated 1,5-cyclooctadiyne 41 from dibromide 38, and a mixture of cyclophanes 45 and 46 from the precursor 43. 1,10-Eliminations were carried out successfully with dibromides 47, 50, and 53 yielding the corresponding unsaturated cyclophanes ("cyclophynes") 49, 52, and 55. The influence of the solvent on the cyclodimerization 47-->49 was investigated, with acetonitrile providing the highest yields. The heterophanes 59 a and b were obtained by 1,10-elimination of the precursor dibromides 57 a and b, and in an elimination experiment involving a 1:1 mixture of the dibromides 50 and 57 b the "mixed dimer" 60 was isolated, besides the homodimers 52 and 59 b. The method reached its limits with the 1,14-elimination of 68, 70, and 74 providing the cyclophanes 69, 71, and 75 in varying amounts. Two final debrominations with 76 and 77, which in principle could undergo 1,16- and 1,20-eliminations reactions, respectively, failed. The structures of the new cyclophanes 49, 50, 59 a, and 59 b were established by X-ray structural analysis; all other structure assignments rest on the usual spectroscopic and analytical data.     

多弧离子镀TiN与不同金属基材间的接触界面与表面特性

用多弧离子镀技术在不同金属基材上进行TiN镀膜实验,制备了TiN/Fe、 TiN/Cu和TiN/Cr/Cu复合膜.借助扫描电子显微镜(SEM)、 X射线衍射仪(XRD)和光电子能谱(XPS),研究了TiN与Fe、 Cu和Cr/Cu三种不同衬底接触界面的形貌、结构及其表面特性.SEM观察发现,在一定离子镀膜条件下, TiN涂层可与Fe、 Cu和Cr/Cu金属基材形成均匀平整的接触界面,在铜基上TiN界面清晰,在Fe与Cr/Cu界面有明显的层状晶界微结晶分布.XRD分析显示, Fe、 Cu和Cr/Cu表面生成的薄膜都包含TiN、 Ti2N等多晶相,在Cr/Cu界面还包含Ti-Cr的金属间化合物.XPS结果表明,表面除了TiN膜外,还生成TiO2和TiOxNy等氧化膜.Ar+刻蚀5 min后, TiO2消失, TiOxNy减少, TiN则呈增加趋势.TiN与Cr/Cu界面形成明显的Ti-Cr和Cr-Ni互扩散层,这有助于增强薄膜附着力,形成较牢固的TiN涂层.     

Waterborne Polyurethane Dispersions and Thin Films: Biodegradation and Antimicrobial Behaviors

Biodegradable and antimicrobial waterborne polyurethane dispersions (PUDs) and their casted solid films have recently emerged as important alternatives to their solvent-based and non-biodegradable counterparts for various applications due to their versatility, health, and environmental friendliness. The nanoscale morphology of the PUDs, dispersion stability, and the thermomechanical properties of the solid films obtained from the solvent cast process are strongly dependent on several important parameters, such as the preparation method, polyols, diisocyanates, solid content, chain extension, and temperature. The biodegradability, biocompatibility, antimicrobial properties and biomedical applications can be tailored based on the nature of the polyols, polarity, as well as structure and concentration of the internal surfactants (anionic or cationic). This review article provides an important quantitative experimental basis and structure evolution for the development and synthesis of biodegradable waterborne PUDs and their solid films, with prescribed macromolecular properties and new functions, with the aim of understanding the relationships between polymer structure, properties, and performance. The review article will also summarize the important variables that control the thermomechanical properties and biodegradation kinetics, as well as antimicrobial and biocompatibility behaviors of aqueous PUDs and their films, for certain industrial and biomedical applications.     

STUDIES ON COMBUSTION BEHAVIOR OF NR/MMT NANO-COMPOSITES BY CONE CALORIMETER

The NR/modified montmorillonite(EMT)nano-composites were prepared by mechanical mixing and reacting in situ with glycidyl methacrylate.Under 30 kW.m~(-2)of heat flux,the combustion behavior of the nano-composites was studied with cone calorimetry,and PHRR,THR,EHC,TSR and MLR were tested.The results showed that the nano- composite had improved mechanical properties and flame retardance properties,and to some extent,the nano-composite had smoke suppress effect.Compared with pure NR,the PHRR,EHC and SPR of the nano-composite reduced by 34%,21% and 16.8%,respectively.     

伊敏褐煤中微量元素的地球化学特征及其无机-有机亲和性分析

采用脱矿物质、提取腐殖酸等方法结合ICP-MS对伊敏15_上、16_下煤中的32种微量元素的含量及其赋存特征进行了分析。与地壳克拉克值及中国侏罗-白垩纪煤和世界褐煤中微量元素含量相比,伊敏褐煤中微量元素没有明显富集。脱矿物质处理后,Ni明显富集,As略比原煤高,其他微量元素都低于原煤。原煤提取腐殖酸和脱矿物煤提取腐殖酸中Ni、Mo、Cd、Sn、W明显富集,这表明Ni、Mo、Cd、Sn、W和腐殖酸形成了稳定的有机态化合物。原煤提取腐殖酸残煤和脱矿物煤提取腐殖酸残煤中V、Ni、As富集,表明V、Ni、As与煤的大分子结构形成了稳定的有机态化合物。根据微量元素和灰分的相关性系数,把微量元素分为以下几类:无机富集元素Cr、U;亲无机元素Cu、Cd、In、Sn、Ga、Y、Zr、Hf、Bi、Th;偏无机元素Be、Sc、Rb、Sr、Nb、Cs、Ta、Pb;偏有机元素V、As、Tl、Ba、Se;亲有机元素Li、Co、W;有机富集元素Ni、Zn、Mo、Sb。     

Diffusion of symmetrical and spherical solutes in protic,aprotic, and hydrocarbon solvents

The diffusion coefficients of a series of symmetrical tetraalkyltins (tetramethyltin, tetraethyltin, tetrapropyltin, tetrabutyltin, tetradodecyltin) of the gases argon, krypton, xenon, methane, and tetramethylmethane and of carbon tetrachloride and tetraethylmethane in hexane, decane, and tetradecane at 25°C have been determined using the Taylor dispersion technique. Diffusion coefficients for the gases in acetone, 2-propanol, 1-butanol, and 1-octanol were also determined. Deviations from the predictions of Stokes' law were found to be large, and the magnitude of the deviation can be directly related to solute size. The predictions of the Hubbard-Onsager equation were tested using the diffusion data.     

Self-Assembling Drug Formulations with Tunable Permeability and Biodegradability

This review focuses on key topics in the field of drug delivery related to the design of nanocarriers answering the biomedicine criteria, including biocompatibility, biodegradability, low toxicity, and the ability to overcome biological barriers. For these reasons, much attention is paid to the amphiphile-based carriers composed of natural building blocks, lipids, and their structural analogues and synthetic surfactants that are capable of self-assembly with the formation of a variety of supramolecular aggregates. The latter are dynamic structures that can be used as nanocontainers for hydrophobic drugs to increase their solubility and bioavailability. In this section, biodegradable cationic surfactants bearing cleavable fragments are discussed, with ester- and carbamate-containing analogs, as well as amino acid derivatives received special attention. Drug delivery through the biological barriers is a challenging task, which is highlighted by the example of transdermal method of drug administration. In this paper, nonionic surfactants are primarily discussed, including their application for the fabrication of nanocarriers, their surfactant-skin interactions, the mechanisms of modulating their permeability, and the factors controlling drug encapsulation, release, and targeted delivery. Different types of nanocarriers are covered, including niosomes, transfersomes, invasomes and chitosomes, with their morphological specificity, beneficial characteristics and limitations discussed.     

Biogenic Sulfur-Based Chalcogenide Nanocrystals: Methods of Fabrication,Mechanistic Aspects,and Bio-Applications

Bio-nanotechnology has emerged as an efficient and competitive methodology for the production of added-value nanomaterials (NMs). This review article gathers knowledge gleaned from the literature regarding the biosynthesis of sulfur-based chalcogenide nanoparticles (S-NPs), such as CdS, ZnS and PbS NPs, using various biological resources, namely bacteria, fungi including yeast, algae, plant extracts, single biomolecules, and viruses. In addition, this work sheds light onto the hypothetical mechanistic aspects, and discusses the impact of varying the experimental parameters, such as the employed bio-entity, time, pH, and biomass concentration, on the obtained S-NPs and, consequently, on their properties. Furthermore, various bio-applications of these NMs are described. Finally, key elements regarding the whole process are summed up and some hints are provided to overcome encountered bottlenecks towards the improved and scalable production of biogenic S-NPs.     

醛类标志物的化学衍生化色谱-质谱分析方法进展

人体接触环境中的化学污染物会导致多种疾病,包括癌症、糖尿病、心血管疾病、神经退行性疾病(阿尔茨海默症、帕金森病等)等.作为一类具有高反应活性的亲电化合物,醛类(包括外源性醛类或环境污染物暴露后产生的内源性醛类)可与人体中多种重要生物分子形成共价修饰产物而产生毒害作用.暴露组研究自2005年被首次提出以来一直是一个前沿热...     

表面活性剂与叶酸的相互作用及其对光氧化降解的影响

表面活性剂与有机小分子作用不仅能提高表面活性剂的聚集能力,还能提高小分子的溶解度、稳定性等应用性能,因此研究二者之间的相互作用机理对于促进表面活性剂的发展和实际应用具有重要意义。本工作提出了一种利用功能有机小分子调控表面活性剂聚集行为,进而提高不稳定小分子自身稳定性的新策略。利用表面张力、紫外可见吸收光谱、荧光光谱、动态光散射、等温滴定量热和核磁共振技术研究了在p H为7.0时,叶酸分别与十二烷基硫酸钠(SDS)、十二烷基三甲基溴化铵(DTAB)、季铵盐Gemini 12-6-12和季铵盐线性三聚12-3-12-3-12四种表面活性剂之间的相互作用及其导致的叶酸光氧化降解性能的变化,结果表明,阴离子表面活性剂SDS抑制叶酸光氧化降解的效率较低,而阳离子表面活性剂都能够显著抑制叶酸的光氧化降解,且随着表面活性剂寡聚度的增加,抑制效果增强,所需表面活性剂的浓度显著降低,寡聚表面活性剂12-3-12-3-12的抑制效率高达96%。     

智能响应材料在磷酸化肽和糖肽富集中的应用

蛋白质的磷酸化和糖基化作为研究最广泛的两种翻译后修饰(PTMs),在疾病的早期无创诊断、预后和治疗评估中表现出越来越大的潜力。蛋白质的异常磷酸化和糖基化经常被用于临床蛋白质组学研究和疾病相关生物标志物的发现。目前已有多种材料被开发用于磷酸化肽和糖肽的富集研究,其中,智能响应材料由于具有独特的响应特性,已被陆续报道用于磷酸化肽和糖肽的富集。智能响应材料可对外界刺激做出响应,发生结构和性质上的变化,将光、电、热、机械等信号转化为生物化学信号。响应分子是决定智能响应材料响应特性的先决条件,它们在不同刺激条件下(如温度、pH、光、机械应力、电磁场等)的可逆异构化将导致材料的宏观物理和化学性质的动态变化。与传统材料相比,智能响应材料可以可逆地“打开”和“关闭”,具有更好的可调控性。由于引起智能材料响应的刺激信号对其性能具有重要的影响,综述根据施加的刺激种类对智能响应材料进行分类,具体分为外源性响应材料和内源性响应材料,且分别总结了外源性响应材料、内源性响应材料以及内外源共同响应材料在磷酸化肽和糖肽富集方面的工作。此外,综述对智能响应材料在磷酸化肽和糖肽富集方面的发展前景进行了展望,并且提出了智能响应材料在其他蛋白质翻译后修饰方面的应用中存在的挑战。     

预还原氢化物发生—原子荧光光谱法快速测定化探样品中的As,Sb,Bi,Hg

通过对化探样品进行王水密闭溶解,饱和的硫脲-抗坏血酸预还原,运用氢化物发生-原子荧光光谱法实现了地质样品中As、Sb、Bi、Hg元素的任意配对以及连续快速测定。实验确定了原子化器高度为14mm,最佳溶样时间为1h。在优化条件下,结果显示还原剂(硫脲-抗坏血酸)对Hg、Bi测定结果无影响,且Hg、Bi测定结果在预还原20min至48h内都很稳定,测定结果良好,Cu、Co、Ni、Au、Ag、Cd、As、Sb、Bi、Se、Ge等金属离子对预还原测定汞均无干扰,对比实验表明还原剂体系下汞荧光强度值基本不变。方法的检出限低、精密度好、准确度高、操作简便,有效避免了元素污染问题,可满足大批量地质样品分析测定的需要。     

天然化合物芦丁的治疗潜力

芦丁属于类黄酮化合物,广泛存在于人们日常食用的各种蔬菜、水果和中草药中。 芦丁是天然的抗氧化剂,有清除自由基的特性,可调节众多疾病有关的细胞内和细胞外信号通路,影响细胞的生长,分化及其功能,对人们的健康,防病治病起着重要作用。芦丁具有广泛的药理活性,抗氧化、抗炎、抗病毒、抗癌、预防和治疗心脑血管疾病。以芦丁为原料的药品有多种,使用芦丁毒副作用小,安全,成本低。由于芦丁的生物利用度低,在临床上应用受到一定的限制。克服芦丁溶解性差的问题已经有各种方法,例如使用环糊精的络合,磷脂等,改善水溶性,从而增加生物利用度。本文综述了芦丁的多种潜在用途和治疗作用的信息,与药物输送相关的问题,以及改善药物生物利用度的可能方法。重点介绍了芦丁的抗炎、抗癌、降糖、对心血管的保护作用,为天然化合物的开发和利用奠定基础。