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amphiphilicsodiumalginatevinylacetatemicroparticlesfordrugdelivery
No full textTo overcome the fast or burst release of hydrophilic drugs from hydrophilic alginate-based carriers,hydrophobic molecule(vinyl acetate,VAc)was grafted on alginate(Alg),which was further used to prepare drug carriers.Amphiphilic Alg-g-PVAc hydrogel beads were firstly prepared by emulsification/internal gelation technique for the loading of bovine serum albumin(BSA).Then,chitosan was coated on the surface of beads to form novel amphiphilic Alg-g-PVAc/chitosan(Alg-g-PVAc/CS)microcapsules.The BSA-loading amphiphilic Alg-g-PVAc/chitosan(Alg-g-PVAc/CS)microcapsules display similar morphology and size to the hydrophilic alginate/chitosan(AC)microcapsules.However,the drug loading and loading efficiency of BSA in Alg-g-PVAc/CS microcapsules are higher,and the release rate of BSA from Alg-g-PVAc/CS microcapsules is slower.The results demonstrate that the introduction of hydrophobic PVAc on alginate can effectively help retard the release of BSA,and the higher degree of substitution is,the slower the release rate is.In addition,the complex membrane can also be adjusted to delay the release of BSA.As a whole,amphiphilic sodium alginate-vinyl acetate/CS microparticles could be developed for macromolecular drug delivery
synthesisesstructuresandantibacterialactivitiesofaseriesofrareearthnitrogenheterocycliccomplexes
No full textA series of rare earth metal complexes, Ln( IAA )(2)( phen )(2) center dot ( NO3) Ln=Ce(1), Gd( 2), Tb (3), Dy( 4 ), Ho (5). HIAA = indole acetic acid, phen = 1, 10-phenanthrolin
ecofriendlysynthesisofhighsilicazeoliteywithcholineasgreenandinnocentstructuredirectingagent
No full text分子筛作为一类重要的无机多孔晶体材料,由于其规整的孔道结构以及优异的酸性质等特点,在催化剂、吸附剂和离子交换床等许多领域有着重要而广泛的应用.而现代分子筛制备方法的发展主要得益于有机结构导向剂(OSDA)在分子筛合成中的广泛使用.但是,大部分OSDA都具有剧毒、价格昂贵、制备方法繁琐等缺点,因而限制了其大规模应用.高硅Y型分子筛的合成研究也面临同样的问题.Y型分子筛具有十二元环孔口和三维孔道结构,是目前催化裂化催化剂中的主要活性组分.目前,通过常规合成方法无法获得硅铝比大于6.0的Y型分子筛,无法满足石油化工对其酸性的要求.目前工业上主要通过后处理法得到高硅Y沸石,但该方法繁杂的后处理过程、不均匀的化学分布、大量损失的结晶度以及严重的环境污染促使人们开发直接合成高硅Y型分子筛的新方法以替代后处理过程.此外,使用OSDA一步法合成的高硅铝比Y型分子筛具有优异的热和水热稳定性.因此,使用OSDA一步直接合成高硅Y型分子筛在材料合成和催化领域一直备受关注.然而,目前尚未见关于绿色OSDA用于高硅Y型分子筛合成的报道.本研究首次将氢氧化胆碱或氯化胆碱作为一种新型、绿色、廉价的OSDA引入到高硅Y分子筛的合成凝胶体系,成功合成了高结晶度且硅铝比大于6.0的高硅Y型分子筛.实验详细考察了合成条件对硅铝比的影响,并采用XRD,XRF,NMR,TG以及N2物理吸附等表征手段研究了合成样品的物理化学性质.表征结果证明,胆碱阳离子作为一个稳定的OSDA存在于分子筛的孔结构中,并且取代了部分Na+以平衡分子筛骨架的负电荷,因此胆碱的使用可使样品的硅铝比提高并具有更加优异的热稳定性和水热稳定性.实验确定了Na^+和OSDA^+在高硅Y分子筛合成中的竞争关系.大量的实验证据表明,Na^+进料比例对FAU骨架硅铝比有决定性的影响.首次提出采用氢氧根离子型OSDA是一种直接有效提高骨架硅铝比的方法
structuralanalysisofhighdegreepolymerizationisomersofhumanmilkoligosaccharidesbasedonelectrosprayionizationquadrupoletimeofflightmassspectrometry
No full textHuman milk oligosaccharides are a kind of natural prebiotics that exist in human milk. They play an irreplaceable role in the growth of infantile intestinal flora, the improvement of immune system and the resistance to pathogen infection. The function of human milk oligosaccharides is closely related to their structures which are complex with various linkages. Besides , the oligosaccharides have a large number of isomers , the number and complexity of which increase dramatically with the degrees of their polymerization. Therefore , the structural analysis of oligosaccharide isomers with a high degree of polymerization is one of the difficulties in the study of human milk oligosaccharides , and is of great significance for the study of the biological function of oligosaccharides. In this study , electrospray ionization-quadrupole-time of flight mass spectrometry ( ESI-Q/TOF-MS ) was used to analyze the structures of eighteen high-degree polymerized human milk oligosaccharides in a negative ion mode , and three of them were firstly reported. Differences of fragment ions between the isomers were discussed, and the cleavage rules of oligosaccharide isomers were summarized. This study provided a scientific basis for the structural analysis of the complex isomers of highly polymerized human milk oligosaccharides and the discovery of novel sugar structures
Activation and Spillover of Hydrogen on Sub-1nm Palladium Nanoclusters Confined within Sodalite Zeolite for the Semi-Hydrogenation of Alkynes
No full textThe search for efficient nontoxic catalysts able to perform industrial hydrogenations is a topic of interest, with relevance to many catalytic processes. Herein, we describe a mechanistic phenomenon for the activation and spillover of hydrogen for remarkable selectivity in the semi-hydrogenation of acetylene over sub-1nm Pd nanoclusters confined within sodalite (SOD) zeolite (Pd@SOD). Specifically, hydrogen is dissociated on the Pd nanoclusters to form hydrogen species (i.e., hydrogen atoms and hydroxyl groups) that spill over the SOD surfaces. The design and utilization of the small-pore zeolite SOD (six-membered rings with 0.28x0.28nm channels) is crucial as it only allows H-2 diffusion into the channels to reach the encapsulated Pd nanoclusters and thus avoids over-hydrogenation to form ethane. Pd@SOD exhibits an ethylene selectivity of over 94.5%, while that of conventional Pd/SOD is approximately 21.5%
Open Foundation of State Key Laboratory of Environmental Chemistry and Ecotoxicology[KF2018-19]
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Visible-light-driven coproduction of diesel precursors and hydrogen from lignocellulose-derived methylfurans
No full textPhotocatalytic hydrogen production from biomass is a promising alternative to water splitting thanks to the oxidation half-reaction being more facile and its ability to simultaneously produce solar fuels and value-added chemicals. Here, we demonstrate the coproduction of H-2 and diesel fuel precursors from lignocellulose-derived methylfurans via acceptorless dehydrogenative C-C coupling, using a Ru-doped ZnIn2S4 catalyst and driven by visible light. With this chemistry, up to 1.04 g g(catalyst)(-1)h(-1) of diesel fuel precursors (similar to 41% of which are precursors of branched-chain alkanes) are produced with selectivity higher than 96%, together with 6.0 mmol g(catalyst)(-1) h(-1) of H-2. Subsequent hydrodeoxygenation reactions yield the desired diesel fuels comprising straight- and branched-chain alkanes. We suggest that Ru dopants, substituted in the position of indium ions in the ZnIn2S4 matrix, improve charge separation efficiency, thereby accelerating C-H activation for the coproduction of H-2 and diesel fuel precursors
