中国纤维素乙醇技术的研究进展

中国面临着严重的能源短缺和环境污染问题,中国政府正在局部几个省份内政策性鼓励燃料乙醇生产和使用.尽管当前主要是用玉米和谷物作为生产乙醇的原料,然而中国具有大量潜在的低成本的纤维素生物质原料,可以极大地扩大乙醇的产量,降低原料成本.近20年来,由于技术的革命性进步,已使得纤维素乙醇的生产成本从4美元/加仑以上,降低至约1.2-1.5美元/加仑.其中,每吨生物质约44美元.因此,目前乙醇掺汽油具有十分强的市场竞争力.已有几个公司正在建造首批商业纤维素乙醇工厂,虽然这些刚起步的小型设施在合理利用和管理上风险较小,但规模经济需要较大型工厂.尽管配送生物质原料的成本会随需求的增加而增加,但在乙醇生产基础上的生物精炼技术的发展,尤其是化工产品和动力的协同生产,将会使全过程的经济可行性大大提高.进一步深入的基础研究,将解决低成本下实现纤维素的完全利用,以确保在无政策性补贴的前提下,真正使纤维素乙醇成为具有市场竞争力的低成本纯液体燃料.     

常温常湿条件下Au/MeO~x催化剂上CO氧化性能

利用共沉淀法制备了Au/MeO~x催化剂(Me=Al,Co,Cr,Cu,Fe,Mn,Ni,Zn)。在常温常湿条件下,考察了不同氧化物负载的金基催化剂的CO氧化性能。结果表明,氧化物种类对催化剂的活性和稳定性均有较大的影响。Cu,Mn,Cr等氧化物负载的金基催化剂的活性较差,而Zn,Fe,Co,Ni,Al等金属氧化物负载的金基催化剂可将CO完全氧化,又具有一定的稳定性,在相同反应条件下,CO完全转化时的稳定性顺序为Au/ZnO>Au/α-Fe~2O~3>Au/Co~3O~4>Au/γ-Al~2O~3≈Au/NiO。还发现水对Au/MnO~x催化剂的活性和稳定性有负作用,而对180℃焙烧制备的Au/ZnO-180催化剂的活性和稳定性均有明显的湿度增强作用。     

引言

中药在中国有着几千年的临床使用经验。随着民众对药品有效性和安全性认识的加深,中药质量受到越来越多的重视,中药质量控制也随之成为保障中药产业发展的重要因素之一和中药现代化研究的重要内容之一。由于中药的复杂性、多样性和物质基础研究的局限性,中药质量控制技术的发展成为中药质量控制的关键。随着中药物质基础、药理活性研究的深入和现代分离分析技术对复杂体系分析能力的提高,中药质量控制水平有了明显的提高;在认识到中药药效是多靶点、多成分的协同作用特点后,多指标成分定量成为中药含量测定的发展趋势。近年来,着重于从整体上进行质量控制的指纹图谱技术得到了广泛的关注和应用,并已被国外认可,成为建立国际性中药质量标准的技术纽带。各种色谱、光谱技术在指纹图谱中的运用及利用现代分离和检测技术获取海量数据,使人们对于中药的认识达到了一个新的高度。海量数据的化学计量学分析更成为鉴别中药真伪、优劣的科学依据。
中药质量控制是一个不断认识和深入的过程,新问题、新理念和新技术的层出不穷为我们提出了一个又一个的新课题。随着研究的深入,各方面的研究成果将为中药质量控制提供更为丰富的科学依据,中药质量控制技术也必然随着中药整体研究水平的提高而发展,并为中药的现代化和国际化做出巨大贡献。由于色谱技术在中药质量控制中发挥了巨大作用,本刊特别邀请了部分具有突出贡献的色谱专家、学者撰写了相关学术论文,在本期编辑出版了“中药质量控制”专栏。希望通过这些专栏文章所介绍的工作及思想,广集思路,不断创新,为进一步提高中药质量控制的研究水平作出贡献。     

食品标准体系的"漏洞"

食品安全关系着人民群众的身体健康和生命安全。自《标准化法》颁布以来,我国标准化工作为确保食品安全做出了较大的贡献。然而,随着经济发展和社会进步,现行的食品标准体系暴露出了许多问题和不足,近年来频频发生的食品质量安全事件,大都与食品标准存在的问题有关。标准化的宗     

镧对Mg-Si合金中Mg2Si相变质的影响

研究了Mg-5Si合金中La的添加对初生Mg2Si相变质的影响。结果表明,适量的La能够有效地变质初生Mg2Si相。基于本文的研究,在添加约0.5%La时,获得了最佳的变质效果,此时,初生Mg2Si相的尺寸减小到25μm以下,其形态从粗大的树枝形状变为多面体形状。然而,当La增加到0.8%或者更高时,初生Mg2Si相又生长为粗大的树枝形态。而且,在凝固过程中发现形成了一些LaSi2化合物,这些化合物的数量随着La的增加而呈现逐渐增加的趋势。     

Na-W-Mn/SiO~2催化剂中Na-Mn协同作用的分子轨道研究

对于甲烷氧化偶联Na-W-Mn/SiO~2催化剂中组分效应的研究表明,单独担载Mn的催化剂非常活泼,具有很强的烃类氧化能力并导致深度氧化产物CO~x的形成;而Na的加入能抑制其活性并对提高催化剂的C~2选择性起了关键作用,对催化剂电子结构及不同金属中心分子轨道的研究揭示了Na-Mn协同作用的机制。催化剂中Na的存在将产生自由电子,处于体相的Mn将在-3eV附近产生空的能带。处于催化剂表面的Mn,无论以分散形式存在或是以氧化物团簇存在,其LUMO能级都很低,具有很强的氧化能力。加入Na以后,由Na产生的自由电子将处在体相Mn产生的空带或占据表面Mn-O中心的低LUMO轨道,其结果,一方面使Na的加入并不使催化剂呈现强的碱性而居致CO~2中毒;另一方面Mn-O中心接受电子后将抑制其强氧化能力保证了催化剂的高选择性。     

CXN天然沸石的研究2: 吸附性质

采用N~2,NH~3,CO~2,乙烯,丙烯,水,甲醇,乙醇,丙醇等作为吸附剂,研究了由我国CXN天然沸石改性制得的H-STI和Na-STI沸石的吸附性质,H-STI和Na-STI沸石的BET表面积及微孔孔体积约为420m^2/g和0.20m^3/g。根据NH~3和CO~2在H-STI沸石上的吸附等温线计算得到它们的吸附热分别为44.8和26.5kJ/mol。乙烯,丙烯,甲醇,乙醇,丙醇等在Na-STI沸石上的吸附等温线表明该沸石对有机分子的吸附具有链长选择性。在低分压下水相对于甲醇的吸附量表明沸石具有一定的疏水性质。     

"开发海水中的化学资源"教学设计

1教材分析上海科学技术出版社出版的高一化学新教材的第二章以“开发海水中的化学资源”为题,分“以食盐为原料的化工产品”、“海水中的氯”、“从海水中提取的重要元素”3节介绍卤素及其化合物的知识。本章知识安排强调化学与生活、化学与化工生产的联系。从学生身边的、熟悉     

纤维素制取乙醇技术

以纤维素为原料生产燃料乙醇由于其原料来源广泛及环保效益良好而被认为是最有前景的生产燃料乙醇的方法之一.以纤维素为原料生产乙醇主要包括水解和发酵两个转化过程.本文介绍了纤维素生产燃料乙醇的原理及工艺过程,同时讨论了各工艺过程需要解决的关键技术问题,分析了过程的经济性,最后介绍了国内外的应用现状,展望了纤维素生产燃料乙醇的产业化前景.     

鉴定用于细胞附着的配体的高通量方法

提供了用于鉴定能够在完整的细胞中产生想要的生物学反应的物质的高通量方法。所述方法包括步骤：提供具有培养表面的容器，将不同的包含单一物质的不同混合物放人选择的容器中，将所述单一物质混合物固定在所述培养表面上。所述方法还包括将被固定的物质与完整的细胞接触，以及获取表示被接触细胞中想要的生物学反应的数据。所述方法也包括使用获得数据的统计模建来确定哪种单一物质的混合物和／或这些混合物中的哪种单一物质对在被接触的细胞中产生想要的生物学反应有效。     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

THE EFFECT OF CLAY DISPERSION ON THE CRYSTALLIZATION AND MORPHOLOGY OF POLYPROPYLENE／CLAY COMPOSITES

PP/clay composites with different dispersions, namely, exfoliated dispersion, intercalated dispersion and agglomerates and particle-like dispersion, were prepared by direct melt intercalation or compounding. The effect of clay dispersion on the crystallization and morphology of PP was investigated via PLM, SAXS and DSC. Experimental results show that exfoliated clay layers are much more efficient than intercalated clay and agglomerates of clay in serving as nucleation agent due to the nano-scale dispersion of clay, resulting in a dramatic decrease in crystal size (lamellar thickness and spherulites) and an increase of crystallization temperature and crystallization rate. On the other hand, a decrease of melting temperature and crystallinity was also observed in PP/clay composites with exfoliated dispersion, due to the strong interaction between PP and clay. Compared with exfoliated clay layers, the intercalated clay layers have a less important effect on the crystallization and crystal morphology. No effect is seen for samples with agglomerates and particle-like dispersion, in regard to melting temperature, crystallization temperature, crystal thickness and crystallinity.     

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.     

Residue‐centric modeling and design of saccharide and glycoconjugate structures

The RosettaCarbohydrate framework is a new tool for modeling a wide variety of saccharide and glycoconjugate structures. This report describes the development of the framework and highlights its applications. The framework integrates with established protocols within the Rosetta modeling and design suite, and it handles the vast complexity and variety of carbohydrate molecules, including branching and sugar modifications. To address challenges of sampling and scoring, RosettaCarbohydrate can sample glycosidic bonds, side‐chain conformations, and ring forms, and it utilizes a glycan‐specific term within its scoring function. Rosetta can work with standard PDB, GLYCAM, and GlycoWorkbench (.gws ) file formats. Saccharide residue‐specific chemical information is stored internally, permitting glycoengineering and design. Carbohydrate‐specific applications described herein include virtual glycosylation, loop‐modeling of carbohydrates, and docking of glyco‐ligands to antibodies. Benchmarking data are presented and compared to other studies, demonstrating Rosetta's ability to predict glyco‐ligand binding. The framework expands the tools available to glycoscientists and engineers. © 2016 Wiley Periodicals, Inc.     

Semiconductor quantum dots and metal nanoparticles: syntheses,optical properties,and biological applications

We review the syntheses, optical properties, and biological applications of cadmium selenide (CdSe) and cadmium selenide–zinc sulfide (CdSe–ZnS) quantum dots (QDs) and gold (Au) and silver (Ag) nanoparticles (NPs). Specifically, we selected the syntheses of QDs and Au and Ag NPs in aqueous and organic phases, size- and shape-dependent photoluminescence (PL) of QDs and plasmon of metal NPs, and their bioimaging applications. The PL properties of QDs are discussed with reference to their band gap structure and various electronic transitions, relations of PL and photoactivated PL with surface defects, and blinking of single QDs. Optical properties of Ag and Au NPs are discussed with reference to their size- and shape-dependent surface plasmon bands, electron dynamics and relaxation, and surface-enhanced Raman scattering (SERS). The bioimaging applications are discussed with reference to in vitro and in vivo imaging of live cells, and in vivo imaging of cancers, tumor vasculature, and lymph nodes. Other aspects of the review are in vivo deep tissue imaging, multiphoton excitation, NIR fluorescence and SERS imaging, and toxic effects of NPs and their clearance from the body. Figure Semiconductor quantum dots and metal nanoparticles have extensive applications, e.g., in vitro and in vivo bioimaging Tamitake Itoh and Abdulaziz Anas contributed equally to this article.     

Tautomeric and conformational isomerism of natural hydroxyanthraquinones

Natural 1,5-di-, 1,4,5-tri-, and 1,4,5,8-tetrahydroxyanthraquinones and their anions and metal complexes were shown to be equilibrium mixtures of tautomers and conformers using quantum-chemical and correlation analysis of elecronic absorption spectra. Solvent effects, ionization, complexation, and the introduction and substitution of substituents were accompanied by shifts of tautomeric and conformational equilibria that determine the color of the compounds. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 224–229, May–June, 2006.     

Selecting polymers for medical devices based on thermal analytical methods

This biomaterials overview for selecting polymers for medical devices focuses on polymer materials, properties and performance. An improved understanding of thermoplastics and thermoset properties is accomplished by thermal analysis for device applications. The medical applications and requirements as well as the oxidative and mechanical stability of currently used polymers in devices are discussed. The tools used to aid the ranking of the thermoplastics and thermosets are differential scanning calorimetry (DSC), thermogravimetry (TG), thermal mechanical analysis (TMA) and dynamic mechanical analysis (DMA) as well as a number of key ASTM polymer tests. This paper will spotlight the thermal and mechanical characterization of the bio-compatible polymers e.g., olefins, nylon, polyacetals, polyvinyl chloride and polyesters.     

乙烷部分氧化制C2氧化物用Fe－Al－P－O催化剂的研究Ⅰ．超细Fe－Al－P－O催化剂的制备与表征

 用溶胶－凝胶法制备了超细Fe－Al－P－O催化剂，并用DTA－TG，BET，TEM，XRD，TPR和IR等技术研究了催化剂的微观组成和结构及其晶格氧活性，探讨了催化剂的制备工艺，考察了溶胶－凝胶的形成机理、凝胶干燥及焙烧条件对催化剂微观组成和结构的影响规律．结果表明，Fe－Al－P－O催化剂呈非晶态，是具有均匀分布的超细粒子（10nm），其比表面积大（238m2／g），晶格氧活性高．FePO4和AlPO4间隔分布在催化剂表面，形成Lewis碱位（P＝O，P－O－Fe）和Lewis酸位（Fe3＋，Al3＋）．     

Recent progress in MXene and graphene based nanocomposites for microwave absorption and electromagnetic interference shielding

There is widespread use of telecommunication and microwave technology in modern society, and raised the electromagnetic interference (EMI) issue to alarming situation due to apprehensive demand and growth of 5G technology undesirably disturbing the human health. The two dimensional (2D) materials including graphene and MXenes are already been used for variety of electronic devices due to their exceptional electrical, mechanical, optical, chemical, and thermal properties. MXene is composed of metal carbides, in which mainly metals are the building blocks for dielectrics, semiconductors, or semimetals. However, the strong interfaces with electromagnetic waves (EM) are variable from terahertz (THz) to gigahertz (GHz) frequency levels and are widely used in EMI and Microwave absorption (MA) for mobile networks and communication technologies. The use of different organic materials with metal, organic, inorganic fillers, polymers nanocomposite and MXene as a novel material has been studied to address the recent advancement and challenges in the microwave absorption mechanism of 2D materials and their nanocomposites. In this concern, various techniques and materials has been reported for the improvement of shielding effectiveness (SE), and theoretical aspects of EMI shielding performance, as well stability of 2D materials particularly MXene, graphene and its nanocomposites. Consequently, various materials including polymers, conducting polymers, and metal–organic frameworks (MOF) have also been discussed by introducing various strategies for improved MA and control of EMI shieling. Here in this comprehensive review, we summarized the recent developments on material synthesis and fabrication of MXene based nanocomposites for EMI shielding and MA. This research work is a comprehensive review majorly focuses on the fundamentals of EMI/MA.  The recent developments and challenges of the MXene and graphene based various structures with different polymeric composites are described in a broader perspective.     

Determination and study on residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg^?1, the maximum residue level of European Union for quizalofop-p-ethyl).