不对称方酸染料的电子结构与光导性的从头算研究

用量子化学从头算法,在RHF/6-31G(d,p)水平上优化了八种不对称方酸染料的分子构型,并对它们的分子内电荷转移程度与暗衰值,光敏值和最大吸收波长的定量关系进行研究,发现不对称方酸染料的分子内电荷转移性质,是影响不对称方酸染料光导性和最大吸收波长的重要因素。     

常低温相变储热材料的研究和应用

将常低温相变储热材料分类,介绍了常低温相变储热材料的种类及各自特点,对固-液相变、固-固相变储热材料的性能、优缺点和应用进行了讨论,讲述了目前人们针对常低温相变储热材料的缺陷采取的解决方法。     

The development for the synthesis of chiral acyclic nucleosides and their phosphonates

Acyclic nucleosides and their phosphonates possess significantly antiviral and cytostatic activities. For acyclic nucleosides and their phosphonates, the introduction of a chiral group to their side chain or the absolute configuration of the chiral atom could affect their biological activities obviously. Thus, the asymmetric synthesis of chiral acyclic nucleosides and their phosphonates has received continuous attention. The previous reports mainly focus on employing the chiral pool and chiral auxiliary methods for the synthesis of chiral acyclic nucleosides and their phosphonates. In contrast, the asymmetric catalysis methods for the synthesis of acyclic nucleosides and their phosphonates are still in the beginning. This digest paper will serve to highlight the significant progress that has been made in these areas.     

V2O5/高硅分子筛的酸性与甲苯气相选择氧化

用固体离子交换法制备了Ｖ２Ｏ５／ＺＳＭ－５和Ｖ２Ｏ５／丝光沸石两类催化剂。通过ＸＲＤ，ＬＲＳ，ＸＰＳ和Ｓｇ测定表征了Ｖ２Ｏ５在分子筛上的分散状态。用吡啶吸附红外光谱法和正丁胺非水溶液回滴法研究了催化剂的表面酸性。用ＥＳＲ研究了甲苯在催化剂上的吸附。结果表明，催化剂的酸性不同，它们吸附甲苯的能力也不同，对甲苯气相选择氧化的活性和选择性也有较大的差异。同时，甲苯选择氧化成苯甲醛的能力还与Ｖ２Ｏ５在分子     

New strategies to study the chemical nature of wine oligomeric procyanidins

Tannins represent a key element in red wine flavors, so researchers have made a lot of effort to try to understand the role of their structure in wine taste in recent decades. We report some new routes to achieve a true structure–taste relationship for the major tannins found in wine, which are procyanidins in their monomeric or oligomeric state. All these routes use synthetic standards. New advances in their synthesis and their analyses using chromatographic methods, NMR spectroscopy, and mass spectrometry to obtain more precise information about their chemical structure, including their stereochemistry and their precise degree of polymerization and galloylation, are described.     

Polymer Networks: A Challenge to Theorist and Technologist

Polymer networks challenge a theorist to develop methods of their generation, describe their topology, and understand critical phenomena (gelation) during their formation. They challenge a technologist because of their unique properties based on their large-scale three-dimensional connectivity and their easy transformation of relatively low-viscosity liquids into crosslinked solids. Polymer networks challenge both, in that they are structurally very complex for the technologist who needs the theorist for understanding and controlling their structure and properties. Also, the theorist is challenged by problems appearing in technology which may initiate a basic reconsideration of the theories' assumptions. In this contribution, methods for modeling polymer network structures and their recent applications to relatively complex systems of technological importance are briefly discussed.     

食物的色、香、味与食品添加剂

食品添加剂可以改善食品的品质,延长食品的保存期,增加食品的营养成分。本文介绍了生活中常见的食品添加剂：食品色素、食用香料、甜味剂、鲜味剂、防腐剂和抗氧化剂的性能、使用范围和化学结构。以便于在化学教学中开阔学生的知识视野,提高学生的学习兴趣,全面培养学生的科学素质。     

Spectral characterization,antimicrobial and antibiofilm activity of poly(propylene imine) metallodendrimers in solution and applied onto cotton fabric

Abstract

Poly(propylene imine) dendrimers from first and third generation modified with 1,8-naphthalimide units and their Cu(II) complexes have been characterized by fluorescence and EPR spectroscopy. Cotton fabric has been modified with these dendrimers and their color characteristics were determined. The antimicrobial activity of dendrimer ligands and their Cu(II) complexes in solution and after their deposition on a cotton fabric was investigated. Good antibacterial effect of dendrimer ligands has been obtained, which is enhanced at their Cu(II) complexes. After their deposition on cotton fabric metallodendrimers exhibit good antibiofilm activity.     

Fluoroarylphosphines as ligands

This short review concentrates on important aspects of fluoroarylphosphines, in particular their synthesis, ligand properties and chemical and catalytic properties of their complexes. Although the electronic, steric and chemical properties of fluoroarylphosphines have been known for 30 years, their use as ligands for homogeneous catalysis and in the synthesis of elaborate multidentate ligands has occurred more recently. The number of recent reports suggests that their importance is growing.     

Adhesives Based on Formaldehyde Condensation Resins

Formaldehyde based resins are by far the most important adhesives for the production of wood based panels. This paper reviews in compact form the main application near features of these products including their composition, their molar mass distribution as well as their hardening behaviour, which all three parameters have decisive influence on the properties of the resins themselves and their performance as wood adhesives.     

From Prebiotic Chemistry to Supramolecular Biomedical Materials: Exploring the Properties of Self-Assembling Nucleobase-Containing Peptides

Peptides and their synthetic analogs are a class of molecules with enormous relevance as therapeutics for their ability to interact with biomacromolecules like nucleic acids and proteins, potentially interfering with biological pathways often involved in the onset and progression of pathologies of high social impact. Nucleobase-bearing peptides (nucleopeptides) and pseudopeptides (PNAs) offer further interesting possibilities related to their nucleobase-decorated nature for diagnostic and therapeutic applications, thanks to their reported ability to target complementary DNA and RNA strands. In addition, these chimeric compounds are endowed with intriguing self-assembling properties, which are at the heart of their investigation as self-replicating materials in prebiotic chemistry, as well as their application as constituents of innovative drug delivery systems and, more generally, as novel nanomaterials to be employed in biomedicine. Herein we describe the properties of nucleopeptides, PNAs and related supramolecular systems, and summarize some of the most relevant applications of these systems.     

聚乳酸类医用生物降解材料的研究进展

聚乳酸由于其突出的优点如生物相容性好、降解产物对人体无毒而倍受重视,并且在生物医学领域的应用中获得了很好的效果。本文对聚乳酸的合成及在医学方面的应用作了总结和评述,并对其在生物医学领域的应用前景作了进一步展望。     

Measurement of nanoparticles by light-scattering techniques

Nanoparticles (NPs), due to their unique physical and chemical properties, especially their minute particle size (?100 nm), find applications in numerous industrial, commercial and consumer products. After their end-user applications, these NPs find their way into the environment and food products. The NPs so discharged need to be quantified accurately to determine their toxicity and exposure levels.At this time, there is a need to develop a unified method for their determination. There are plenty of techniques available in the market that were initially used for colloidal particles (e.g., microscopy, spectroscopy and the recent addition of magnetic resonance), but each of these techniques has a certain degree of uncertainty.Further, sample homogeneity, sample preparation, instrument-operating procedures, and statistical practices are likely to add to the complexity of the problem. In this context, this review attempts to understand the widely-used light-scattering techniques, including their theory, practice and real-world use in determination of NPs in environmental and food applications.     

Biological applications of carbon dots

Carbon dots (C-dots), since their first discovery in 2004 by Scrivens et al. during purification of single-walled carbon nanotubes, have gradually become a rising star in the fluorescent nanoparticles family, due to their strong fluorescence, resistance to photobleaching, low toxicity, along with their abundant and inexpensive nature. In the past decade, the procedures for preparing C-dots have become increasingly versatile and facile, and their applications are being extended to a growing number of fields. In this review, we focused on introducing the biological applications of C-dots, hoping to expedite their translation to the clinic.     

N-heterocyclic carbenes as organocatalysts

Organocatalyzed reactions represent an attractive alternative to metal-catalyzed processes notably because of their lower cost and benign environmental impact in comparison to organometallic catalysis. In this context, N-heterocyclic carbenes (NHCs) have been studied for their ability to promote primarily the benzoin condensation. Lately, dramatic progress in understanding their intrinsic properties and in their synthesis have made them available to organic chemists. This has resulted in a tremendous increase of their scope and in a true explosion of the number of papers reporting NHC-catalyzed reactions. Here, we highlight the ever-increasing number of reactions that can be promoted by N-heterocyclic carbenes.     

Multi‐Stimuli‐Responsive Polymeric Materials

Stimuli‐responsive materials are of immense importance because of their ability to undergo alteration of their properties in response to their environment. The properties of such materials can be tuned by subtle adjustments in temperature, pH, light, and so forth. Among such smart materials, multi‐stimuli‐responsive polymeric materials are of pronounced significance as they offer a wide range of applications and their properties can be tuned through several mechanisms. Here, we aim to highlight some recent studies showcasing the multi‐stimuli‐responsive character of these polymers, which are still relatively little known compared to their single‐stimuli‐responsive counterpart.     

Polycyclic Aromatic Hydrocarbons in Wooden Railway Beams Impregnated with Coal Tar: Extraction and Quantification by GC-MS

 An analytical technique for the simultaneous determination of PAHs (polycyclic aromatic hydrocarbons) in wooden railway beams, impregnated with coal tar for their protection, has been developed, based on the effective extraction of the PAHs and their determination by GC-MS. Two extraction techniques, the Soxhlet and the ultrasonic one, using two different solvents, hexane and toluene have been compared for their efficiency for PAHs which can be determined in ppb-ppt range after optimised clean up and enrichment. Several parameters, such as the degree of impregnation of the wooden beams, the effect of sun radiation on the degradation of the PAHs and their migration to the soil have been investigated by following the concentration of the PAHs and that of their methylated products found at various sampling positions. The results are useful for the decision about recycling procedure or their further disposal.     

The Application of Chitosan Nanostructures in Stomatology

Chitosan (CS) is a natural polymer with a positive charge, a deacetylated derivative of chitin. Chitosan nanostructures (nano-CS) have received increasing interest due to their potential applications and remarkable properties. They offer advantages in stomatology due to their excellent biocompatibility, their antibacterial properties, and their biodegradability. Nano-CSs can be applied as drug carriers for soft tissue diseases, bone tissue engineering and dental hard tissue remineralization; furthermore, they have been used in endodontics due to their antibacterial properties; and, finally, nano-CS can improve the adhesion and mechanical properties of dental-restorative materials due to their physical blend and chemical combinations. In this review, recent developments in the application of nano-CS for stomatology are summarized, with an emphasis on nano-CS’s performance characteristics in different application fields. Moreover, the challenges posed by and the future trends in its application are assessed.     

One-step synthesis of large-aspect-ratio single-crystalline gold nanorods by using CTPAB and CTBAB surfactants

Gold nanorods were prepared in high yields by using a one-step seed-mediated process in aqueous cetyltripropylammonium bromide (CTPAB) and cetyltributylammonium bromide (CTBAB) solutions in the presence of silver nitrate. The diameters of the nanorods range from 3 to 11 nm, their lengths are in the range of 15 to 350 nm, and their aspect ratios are in the range of 2 to 70. The diameters of the Au nanorods obtained from one growth batch in CTPAB solutions decrease as their lengths increase, and their volumes decrease as the aspect ratios increase. The diameters of the Au nanorods obtained from one growth batch in CTBAB solutions first decrease and then slightly increase as their lengths increase, and their volumes increase as the aspect ratios increase. These Au nanorods are single-crystalline and are seen to be oriented in either the [100] or [110] direction under transmission electron microscopy imaging, irrespective of their sizes. To the best of our knowledge, this is the first report of the preparation by using wet-chemistry methods of single-crystalline Au nanorods with aspect ratios larger than 15.