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Synthesis Route (synthesis + route)
Selected AbstractsAn Anhydrous High-Pressure Synthesis Route to Rutile Type RhO2.CHEMINFORM, Issue 11 2007Gerard Demazeau Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] New Synthesis Route to and Physical Properties of Lanthanum Monoiodide.CHEMINFORM, Issue 22 2006Mikhail Ryazanov Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis and Characterization of , -Cyclodextrin Based Functional Monomers and its Copolymers with N -isopropylacrylamideMACROMOLECULAR BIOSCIENCE, Issue 12 2003Yu-Yang Liu Abstract Two novel monovinyl , -cyclodextrin (, -CD) monomers are synthesized. Their chemical compositions are characterized by means of element analysis, NMR and FT-IR spectroscopy. The results show that the synthesis techniques used are convenient and efficient. Using N -isopropylacrylamide as a comonomer, two novel linear copolymers can also be synthesized. Synthesis route of monovinyl , -CD monomers. [source] Synthesis and Characterization of Single-Crystalline Lanthanum Fluoride with a Ring-Like NanostructureEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2009Yang Tian Abstract LaF3 ring-like nanostructures with a diameter of less than 2 ,m have been fabricated by a facile, effective, and environmentally friendly molten salt synthesis route in which NaNO3 and KNO3 (2:1 molar ratio) act as reaction media and the rare-earth nitrate and NaF as precursor. X-ray diffraction, TEM, HR-TEM, energy dispersive X-ray spectroscopy, and photoluminescence spectroscopy are all used to characterize the as-prepared samples. Experiments peformed with different reaction times indicate that a central-etching of the plates from the inner part towards the edge during nanocrystal growth plays a key role in the formation of LaF3 nanorings since no other templates/surfactants are present in our system. Additionally, the luminescence properties of LaF3 nanorings doped with Eu3+ cation have been investigated andcompared with those of bulk materials and nanoparticles with a size of approximately 50 nm. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] 2,3,6,7,10,11-Hexamethoxytribenzotriquinacene: Synthesis, Solid-State Structure, and Functionalization of a Rigid Analogue of CyclotriveratryleneEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2004Marco Harig Abstract The syntheses of several tribenzotriquinacenes bearing six methoxy groups at the outer peripheral positions of the aromatic rings are reported. The centro -methyl derivative is accessible in surprisingly good yield through two-fold cyclodehydration in the final step of a synthesis route which requires special care in the preparation of some electron-rich key intermediates, such as 5,6-dimethoxy-2-methylindane-1,3-dione and bis(3,4-dimethoxyphenyl)methanol. X-ray single-crystal structure analysis of the centro -methyl derivative confirms its C3v -symmetrical molecular structure but, at variance from the parent centro -methyltribenzotriquinacene and the similarly shaped cyclotriveratrylene, the hexamethoxytribenzotriquinacene analog does not form columnar stacks in the solid state. Functionalization of the three benzhydrylic bridgehead positions leads to the tetramethyl analog and the bridgehead triol in good yields. In contrast, attempts to functionalize the ortho positions by nitration or bromination mainly give rise to ring cleavage through electrophilic ipso attack, which parallels the behavior of cyclotribenzylenes and cyclotriveratrylenes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Self-Assembled In-Plane Growth of Mg2SiO4 Nanowires on Si Substrates Catalyzed by Au NanoparticlesADVANCED FUNCTIONAL MATERIALS, Issue 15 2010Zhou Zhang Abstract In-plane growth of Mg2SiO4 nanowires on Si substrates is achieved by using a vapor transport method with Au nanoparticles as catalyst. The self-assembly of the as-grown nanowires shows dependence on the substrate orientation, i.e., they are along one, two, and three particular directions on Si (110), (100), and (111) substrates, respectively. Detailed electron microscopy studies suggest that the Si substrates participate in the formation of Mg2SiO4, and the epitaxial growth of the nanowires is confined along the Si <110> directions. This synthesis route is quite reliable, and the dimensions of the Mg2SiO4 nanowires can be well controlled by the experiment parameters. Furthermore, using these nanowires, a lithography-free method is demonstrated to fabricate nanowalls on Si substrates by controlled chemical etching. The Au nanoparticle catalyzed in-plane epitaxial growth of the Mg2SiO4 nanowires hinges on the intimate interactions between substrates, nanoparticles, and nanowires, and our study may help to advance the developments of novel nanomaterials and functional nanodevices. [source] Synthesis of 2,3-dihydro-1,3,4-thiadiazole, thiazole, and triazolo[4,3- a]pyrimidine derivatives from ethyl benzoylacetateHETEROATOM CHEMISTRY, Issue 2 2004Nora M. Rateb Thiophene and thiazole derivatives can be obtained from potassium salt of ethyl 3-oxo-3-phenyl-2-[(phenylamino)thioxomethyl]propanoate and ethyl chloroacetate in N,N -dimethylformamide solution under different conditions. 2,3-Dihydro-1,3,4-thiadiazoles and triazolo[4,3- a]pyrimidine were obtained from reaction of hydrazonoyl halides with each of thioanilide and pyrimidine-2-thione, respectively. Structures of the newly synthesized compounds were elucidated on the basis of elemental analysis, spectral data, and alternative synthesis route whenever possible. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:107,113, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10222 [source] Promiscuous Zinc-Dependent Acylase-Mediated One-Pot Synthesis of Monosaccharide-Containing Pyrimidine Derivatives in Organic MediumADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Qi Wu Abstract A facile one-pot synthesis route to monosaccharide-containing pyrimidine derivatives was developed by combining the two types of catalytic activities of one enzyme in an organic medium, i.e., the Michael addition/acylation activities of zinc-dependent D -aminoacylase (DA) from Escherichia coli. First, the stepwise approach was investigated. DA showed higher activity towards the Michael addition than acylation in this reaction system. The enzymatic Michael additions of pyrimidines to vinyl acrylate proceeded very rapidly and the initial reaction rates for the Michael addition of pyrimidines to vinyl acrylate were 7.2,16.5,mM,min,1. The catalytic specificity of aminoacylases toward Michael addition was demonstrated by the combination of different control experiments. Then, the two steps could be performed in one pot and a single aminoacylase catalyzed one-pot biotransformation was constructed. Using this strategy, a series of saccharide-pyrimidine complexes with potentially biological and pharmacological applications was prepared efficiently. This high Michael addition activity of zinc-dependent aminoacylases and the novel single aminoacylase-catalyzed one-pot synthesis combining two catalytic activities in vitro is of practical significance in expanding the application of enzymes and in the evolution of new biocatalysts. [source] Synthesis and in vitro degradation of poly(N -vinyl-2-pyrrolidone)-based graft copolymers for biomedical applicationsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2002Carl F. Brunius Abstract This work is devoted to the design of a novel family of hydrosoluble biomaterials: poly(N -vinyl-2-pyrrolidone) (PVP)-based graft copolymers. A synthesis route has been elaborated in which ,-functionalized PVP is prepared via chain-transfer radical polymerization, end-group modified, and subsequently grafted onto a polyhydroxylated backbone, typically dextran or poly(vinyl alcohol). The resulting graft copolymer biomaterials are designed for use in various biomedical applications, particularly as materials with a stronger potential for plasma expansion than already existing products have. The graft copolymers are potentially degradable because the PVP grafts are connected to the polyol backbone via a hydrolytically labile carbonate or ester linkage. The degradation of the graft copolymers was performed in vitro over a period of 6 weeks. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3652,3661, 2002 [source] Synthesis of a Li- and Ta-Modified (K,Na)NbO3 Solid Solution by Mechanochemical ActivationJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2008Tadej Rojac The synthesis of (K0.485Na0.485Li0.03)(Nb0.8Ta0.2)O3 from a mechanochemically activated powder is presented for the first time. Mechanochemical activation, followed by a single calcination step was found to be a powerful technique for synthesizing a homogeneous solid solution with a low amount of contaminant, coming from the milling equipment, and good electrical properties without the need for a multiple calcination procedure involving intermediate wet-milling steps, which are typically required in the conventional solid-state synthesis route. [source] Synthesis and Characterization of Mixed-Metal Oxide Nanopowders Along the CoOx,Al2O3 Tie Line Using Liquid-Feed Flame Spray PyrolysisJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2006Jose Azurdia We report here the use of liquid-feed flame spray pyrolysis (LF-FSP) to produce a series of nanopowders along the CoOx,Al2O3 tie line. The process is a general aerosol combustion synthesis route to a wide range of lightly agglomerated oxide nanopowders. The materials reported here were produced by aerosolizing ethanol solutions of alumatrane [Al(OCH2CH2)3N] and a cobalt precursor, made by reacting Co(NO3)2·6H2O crystals with propionic acid. The compositions of the as-produced nanopowders were controlled by selecting the appropriate ratios of the precursors. Nine samples with compositions (CoO)y(Al2O3)1,y, y=0,1 along the CoOx,Al2O3 tie line were prepared and studied. The resulting nanopowders were characterized by X-ray fluorescence, BET, scanning electron microscopy, high-resolution transmission electron micrographs, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and FTIR. The powders typically consist of single-crystal particles <40 nm diameter and specific surface areas (SSAs) of 20,60 m2/g. XRD studies show a gradual change in powder patterns from ,-Al2O3 to Co3O4. The cobalt aluminate spinel phase is observed at stoichiometries (21 and 37 mol%) not seen in published phase diagrams, likely because LF-FSP processing involves a quench of >1000°C in microseconds frequently leading to kinetic rather than thermodynamic products. Likewise, the appearance of Co3O4 rather than CoO as the end member in the tie line is thought to be a consequence of the process conditions. TGA studies combined with diffuse reflectance FTIR spectroscopic studies indicate that both physi- and chemi-sorbed H2O are the principal surface species present in the as-processed nanopowders. The only sample that differs is Co3O4, which has some carbonate species present that are detected and confirmed by a sharp mass loss event at ,250°C. The thermal behavior of the high cobalt content samples differs greatly from the low cobalt content samples. The latter behave like most LF-FSP-derived nanopowders exhibiting typical 1%,4% mass losses over the 1400°C range due mostly to loss of water and some CO2. The high cobalt content samples exhibit a sharp mass loss event that can be attributed to the decomposition of Co3O4 to CoO. [source] Mechanical Activation-Assisted Synthesis of Pb(Fe2/3W1/3)O3JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2000Seok Khim Ang Perovskite Pb(Fe2/3W1/3)O3 (PFW) was prepared via a mechanical activation-assisted synthesis route from mixed oxides of PbO, Fe2O3, and WO3. The mechanically activated oxide mixture, which exhibited a specific area of >10 m2/g, underwent phase conversion from nanocrystalline lead tungstate (PbWO4) and pyrochlore (Pb2FeWO6.5) phases on sintering to yield perovskite PFW, although the formation of perovskite phase was not triggered by mechanical activation. When heated to 700°C, >98% perovskite phase was formed in the mechanically activated oxide mixture. The perovskite phase was sintered to a density of ,99% of theoretical density at 870°C for 2 h. The sintered PFW exhibited a dielectric constant of 9800 at 10 kHz, which was ,30% higher than that of the PFW derived from the oxide mixture that was not subjected to mechanical activation. [source] Scaleable synthesis route for silicon nanocrystal assembliesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2007S. Limaye Abstract We report on a scaleable synthesis route for highly luminescent silicon nanocrystal assemblies and demonstrate that their emission properties are identical to those known for other systems containing silicon nanocrystals. Structural investigations confirmed that chemically porosified metallurgical grade silicon powder consists of silicon nanocrystal assemblies having nanometer sizes characterized by very high total internal surface area. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Filling of carbon nanotubes for bio-applicationsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007S. Costa Abstract Carbon nanotubes (CNT) provide a smart carrier system on the nanometer scale. The system can be used as a template for ferromagnetic fillers. Such a molecular hybrid is a promising potential candidate for the controlled heating of tumour tissue at the cellular level. This is a key reason why it is important to optimize the synthesis route of metal filled carbon nanotubes with regards bulk scale synthesis and purity. In the current study we present multiwalled carbon nanotubes filled with ,-iron phase (Fe-MWCNT). The influence of acid treatment on the stability of the filling and the sample purity is also presented. High resolution transmission microscopy, its Energy dispersive X-Ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) modes have been applied for the analysis of the morphology and chemical composition of the samples. The phase of iron nanowires encapsulated into the carbon nanotubes was determined with selected area electron diffraction (SAED) on a local scale. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Polymerizability, copolymerizability, and properties of cyanoacrylate-telechelic polyisobutylenes I: three-arm star cyanoacrylate-telechelic polyisobutylenePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10 2007Yongmoon Kwon Abstract This series of papers concern new materials for possible biological applications created by combining the chemistry of highly reactive cyanoacrylates (CAs) with polyisobutylene (PIB) rubbers. First, a new strategy for the synthesis of CA,telechelic PIBs is described. Subsequently, the strategy is employed for the synthesis of low viscosity (syringible) CA,telechelic three-arm star PIB [Ø(PIB,CA)3]. The intermediates of the synthesis route are characterized by 1H NMR spectroscopy. Injecting liquid Ø(PIB,CA)3 into living tissue (fresh chicken egg) produces a bolus of crosslinked PIB rubber. The spectacular oxidative resistance of this rubber is documented by its resistance to concentrated HNO3. A structural model of the crosslinked rubber obtained upon contacting Ø(PIB,CA)3 with proteinaceous tissue is proposed. Copyright © 2007 John Wiley & Sons, Ltd. [source] Synthesis of Anatase TiO2 Nanoparticles with ,-Cyclodextrin as a Supramolecular ShellCHEMISTRY - AN ASIAN JOURNAL, Issue 5 2006Landong Li Abstract We report a novel, green hydrothermal-synthesis route to well-dispersed anatase TiO2 nanoparticles with particle sizes of 9,16,nm in the presence of ,-CD (,-cyclodextrin). During the synthesis process, the CD-containing synthesis mixture assembled in both longitudinal and latitudinal directions. Driven by the interaction between molecules, the ,-CDs assembled in the longitudinal direction to form long-chain compounds, whereas in the latitudinal direction, they tended to form regular aggregates through coordination with the Ti species from the hydrolysis of tetrabutyl titanate. In view of the effect of the coordination and the steric hindrance of ,-CDs as a supramolecular shell, homogeneous nuclei and slow growth of TiO2 crystals during the synthesis process was observed, which was responsible for the formation of uniform TiO2 nanoparticles. The low ,-CD dosage and the high product yield (>90,%) demonstrated well the potential of this synthesis route in the large-scale industrial production of anatase nanoparticles. [source] Antimony-Doped Tin Oxide Nanocrystals: Synthesis and Solubility Behavior in Organic SolventsCHEMPHYSCHEM, Issue 5 2009Rafael O. da Silva Abstract The right mix: SnO2:Sb nanocrystals (NCs) can be solubilized into organic solvents with a suitable solvent/surfactant combination to achieve a stable colloid (see picture). A single synthesis route and different solvent/amphiphilic molecule pairs are used to obtain soluble NC colloids, instead of requiring several syntheses to obtain soluble NCs in different solvents. This work focuses on the nonaqueous synthesis of antimony-doped tin oxide nanocrystals in the size range of 2,6 nm and the investigation of their solubility in organic solvents (CHCl3 and THF) in the presence of amphiphilic molecules (oleic acid and oleylamine). To unravel the underlying processes, a set of molecular dynamics simulations is performed involving the compatibility of oleic acid and oleylamine in mixtures with both CHCl3 and THF. The results show that the method is useful for obtaining the desired oxide, and that the interaction between amphiphilic molecules and solvents can be predicted by molecular dynamics simulations with very good qualitative agreement. [source] Novel Nanoparticle-Reinforced Metal Matrix Composites with Enhanced Mechanical PropertiesADVANCED ENGINEERING MATERIALS, Issue 8 2007C. Tjong Abstract This paper summarizes and reviews the state-of-the-art processing methods, structures and mechanical properties of the metal matrix composites reinforced with ceramic nanoparticles. The metal matrices of nanocomposites involved include aluminum and magnesium. The processing approaches for nanocomposites can be classified into ex-situ and in-situ synthesis routes. The ex-situ ceramic nanoparticles are prone to cluster during composite processing and the properties of materials are lower than the theoretical values. Despite the fact of clustering, ex-situ nanocomposites reinforced with very low loading levels of nanoparticles exhibit higher yield strength and creep resistance than their microcomposite counterparts filled with much higher particulate content. Better dispersion of ceramic nanoparticles in metal matrix can be achieved by using appropriate processing techniques. Consequently, improvements in both the mechanical strength and ductility can be obtained readily in aluminum or magnesium by adding ceramic nanoparticles. Similar beneficial enhancements in mechanical properties are observed for the nanocomposites reinforced with in-situ nanoparticles. [source] Comparison between Nafion® and a Nafion® Zirconium Phosphate Nano-Composite in Fuel Cell ApplicationsFUEL CELLS, Issue 3-4 2006F. Bauer Abstract A comparative investigation of the electrical, mechanical, and chemical behaviour of zirconium phosphate-Nafion® composite membranes and Nafion® by means of ex-situ measurements, as well as with fuel cell operation, reveals a slight reduction of ionic conductivity, a significant improvement of mechanical stability, and increased water retention for the composite materials. The overall efficiency at 130,°C is increased during direct methanol fuel cell (DMFC) operation because the reduction in the ionic conductivity is overcompensated for by the decrease in methanol crossover. With H2 as the fuel, the slight reduction in overall efficiency corresponds to the decrease in ionic conductivity. The dimensional stability of the membrane and the membrane electrode assembly (MEA) is significantly improved for operating temperatures above 100,°C. A model for the microstructure-property relation for PFSA-Zr(HPO4)2,·,n,H2O composite membranes is presented, based on the experimental results from membranes with varying filler contents and distributions, obtained through different synthesis routes. It is aimed at the improvement of water distribution in the membrane upon fuel cell operation. [source] A review of catalytic approaches to waste minimization: case study,liquid-phase catalytic treatment of chlorophenolsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2005Mark A Keane Abstract Effective waste management must address waste reduction, reuse, recovery/recycle and, as the least progressive option, waste treatment. Catalysis can serve as an integral green processing tool, ensuring lower operating pressures/temperatures with a reduction in energy requirements while providing alternative cleaner synthesis routes and facilitating waste conversion to reusable material. The case study chosen to illustrate the role that catalysis has to play in waste minimization deals with the conversion of toxic chlorophenols in wastewater. The presence of chloro-organic emissions is of increasing concern with mounting evidence of adverse ecological and public health impacts. A critical overview of the existing treatment technologies is provided with an analysis of the available literature on catalytic dechlorination. The efficacy of Pd/Al2O3 to promote the hydrogen-mediated dechlorination of mono- and dichlorophenols is demonstrated, taking account of both the physical and chemical contributions in this three-phase (solid catalyst and liquid/gaseous reactants) system. Hydrodechlorination activity and selectivity trends are discussed in terms of chloro-isomer structure, the influence of temperature is discussed, the role of base (NaOH) addition is examined and the feasibility of catalyst reuse is addressed. Copyright © 2005 Society of Chemical Industry [source] Preparation and Properties of Porous Aluminum Nitride,Silicon Carbide Composite CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2004Eirik Hagen Microporous two-phase AlN,SiC composites were prepared using Al4C3 and either Si (N2 atmosphere) or Si3N4 (Ar atmosphere) as precursors. The reaction mechanisms of the two synthesis routes and the effect of processing conditions on reaction rate and the material microstructures were demonstrated. The exothermic reaction between Si and Al4C3 under N2 atmosphere was shown to be a simple processing route for the preparation of porous two-phase AlN,SiC materials. The homogeneous two-phase AlN,SiC composites had a grain size in the range of 1,5 ,m, and the porosity varied in the range of 36%,45%. The bending strength was 50,60 MPa, in accordance with the high porosity. [source] Simple enzymatic procedure for l -carnosine synthesis: whole-cell biocatalysis and efficient biocatalyst recyclingMICROBIAL BIOTECHNOLOGY, Issue 1 2010Jan Heyland Summary , -Peptides and their derivates are usually stable to proteolysis and have an increased half-life compared with , -peptides. Recently, , -aminopeptidases were described as a new enzyme class that enabled the enzymatic degradation and formation of , -peptides. As an alternative to the existing chemical synthesis routes, the aim of the present work was to develop a whole-cell biocatalyst for the synthesis and production of , -peptides using this enzymatic activity. For the optimization of the reaction system we chose the commercially relevant ,,, -dipeptide l -carnosine (, -alanine- l -histidine) as model product. We were able to show that different recombinant yeast and bacteria strains, which overexpress a , -peptidase, could be used directly as whole-cell biocatalysts for the synthesis of l -carnosine. By optimizing relevant reaction conditions for the best-performing recombinant Escherichia coli strain, such as pH and substrate concentrations, we obtained high l -carnosine yields of up to 71%. Long-time as well as biocatalyst recycling experiments indicated a high stability of the developed biocatalyst for at least five repeated batches. Application of the recombinant E. coli in a fed-batch process enabled the accumulation of l -carnosine to a concentration of 3.7 g l,1. [source] Addressing chemical diversity by employing the energy landscape conceptACTA CRYSTALLOGRAPHICA SECTION A, Issue 5 2010Martin Jansen Exploring the structural diversity of a chemical system rests on three pillars. First, there is the global exploration of its energy landscape that allows one to predict which crystalline modifications can exist in a chemical system at a given temperature and pressure. Next, there is the development of new synthesis methods in solid-state chemistry, which require only very low activation energies such that even metastable modifications corresponding, for example, to minima on the landscape surrounded by low barriers can be realized. Finally, there is the theoretical design of optimal synthesis routes, again based on the study of the system's energy landscape. In this paper the energy landscape approach to the prediction of stable and metastable compounds as a function of temperature and pressure is presented, with a particular focus on possible phase transitions. Furthermore, several examples are presented, where such predicted compounds were subsequently successfully synthesized, often employing a newly developed synthesis method, low-temperature atom-beam deposition. [source] Two synthesis routes of organometallic precursors for the elaboration of SiCNYO pre-alloyed nanopowdersAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2010Sirine Chehaidi Abstract Two routes were simultaneously investigated to prepare organometallic precursors. They were characterized by NMR and FTIR techniques. In the first route, yttrium acetate was silylated by trimethylchlorosilane before its dissolution in hexamethydisilazane. That leads to a liquid precursor containing SiCNYOH elements. In the second route, a precursor with the same elements was elaborated by dissolution of an amminolysed yttrium compound in tetramethyldisiloxane. The amminolysed yttrium compound was obtained through the amminolysis of the yttrium trichloride by triethylamine [N(C2H5)3]. Copyright © 2010 John Wiley & Sons, Ltd. [source] Nanoparticles by chemical synthesis, processing to materials and innovative applications,APPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2001Helmut Schmidt Abstract Nanoparticles have been fabricated by using chemical synthesis routes under specific conditions. During a precipitation process from liquid phases, surface controlling agents (SCAs) have been added during or shortly after the formation of precipitates. These interfere with the nucleating and growing particle to avoid agglomeration and to control size. Nanoparticles from many systems have been fabricated. If the SCAs are bifunctional, the surfaces chemistry could be tailored and the zeta potential of these particles was tailored also. SiO2 particles have been used for gene targeting using this approach. In other investigations, FeOx nanoparticles have been surface modified by amino groupings together with a sonochemical route to obtain very stable coatings. These particles have been used for in vitro tumor cell penetration and hyperthermal treatment. Boehmite nanoparticles were used to serve as condensation catalysts to prepare very hard transparent coatings for polycarbonate and an overcoat with polymerizable nanoparticles was used to produce anti-reflective and ultrahard coatings. In systems with incorporated fluoro silanes, leading to low surface free energy coatings, nanoparticles were used to tailor the fluorine depth profile in self-aligning transparent easy-to-clean coatings by influencing the critical micelle concentration. The examples show the usefulness of the chemical nanoparticle approach for nanocomposite fabrication and the high potential of these materials for medical and industrial application. Copyright © 2001 John Wiley & Sons, Ltd. [source] Efficient phase separation and product recovery in organic-aqueous bioprocessing using supercritical carbon dioxideBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2010Christoph Brandenbusch Abstract Biphasic hydrocarbon functionalizations catalyzed by recombinant microorganisms have been shown to be one of the most promising approaches for replacing common chemical synthesis routes on an industrial scale. However, the formation of stable emulsions complicates downstream processing, especially phase separation. This fact has turned out to be a major hurdle for industrial implementation. To overcome this limitation, we used supercritical carbon dioxide (scCO2) for both phase separation and product purification. The stable emulsion, originating from a stereospecific epoxidation of styrene to (S)-styrene oxide, a reaction catalyzed by recombinant Escherichia coli, could be destabilized efficiently and irreversibly, enabling complete phase separation within minutes. By further use of scCO2 as extraction agent, the product (S)-styrene oxide could be obtained with a purity of 81% (w/w) in one single extraction step. By combining phase separation and product purification using scCO2, the number of necessary workup steps can be reduced to one. This efficient and easy to use technique is generally applicable for the workup of biphasic biocatalytic hydrocarbon functionalizations and enables a cost effective downstream processing even on a large scale. Biotechnol. Bioeng. 2010;107:642,651. © 2010 Wiley Periodicals, Inc. [source] | |||||||||||||||||||