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Inorganic Compounds (inorganic + compound)
Selected AbstractsPeter Comba, Trevor W Hambley and Bodo Martin Molecular Modeling of Inorganic Compounds (3rd Edition) Wiley-VCH, 2009, 344 pp. (hardback) ISBN 978-3-527-31799-8APPLIED ORGANOMETALLIC CHEMISTRY, Issue 7 2010Alan Hinchliffe No abstract is available for this article. [source] Theoretical Studies of Inorganic Compounds.CHEMINFORM, Issue 4 2004Part 32. Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Theoretical Studies of Inorganic Compounds.CHEMINFORM, Issue 36 2002Part 19. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] The Solid State Electrochemistry of Dysprosium(III) Hexacyanoferrate(II)ELECTROANALYSIS, Issue 17 2005Ping Wu Abstract A new electroactive polynuclear inorganic compound of rare earth metal hexacyanoferrate, dysprosium hexacyanoferrate (DyHCF), was prepared chemically and characterized using techniques of FTIR spectroscopy, thermogravimetric analysis (TGA), UV-vis spectrometry and X-ray photoelectron spectroscopy (XPS) etc. The cyclic voltammetric behavior of DyHCF mechanically attached to the surface of graphite electrode was well defined and exhibited a pair of redox peaks with the formal potential of 217,mV (vs. SCE) at a scan rate of 100,mV/s in 0.2,M NaCl solution and the redox peak currents increased linearly with the square root of the scan rates. [source] Stable Blue Emission from a Polyfluorene/Layered-Compound Guest/Host Nanocomposite,ADVANCED FUNCTIONAL MATERIALS, Issue 7 2006E. Aharon Abstract In this study a blue-light-emitting conjugated polymer, poly(9,9-dioctylfluorene), is confined to the interlayer space of inorganic, layered metal dichalcogenide materials, metallic MoS2, and semiconducting SnS2. The nanocomposites are prepared through Li intercalation into the inorganic compound, exfoliation, and restacking in the presence of the polymer. X-ray diffraction and optical absorption measurements indicate that a single conjugated polymer monolayer, with an overall extended planar morphology conformation, is isolated between the inorganic sheets, so that polymer aggregation or ,,, interchain interactions are significantly reduced. Photoluminescence (PL) measurements show that the appearance of the undesirable green emission observed in pristine polymer films is suppressed by incorporating the polymer into the inorganic matrix. The blue emission of the intercalated polymer is stable for extended periods of time, over two years, under ambient conditions. Furthermore, the green emission is absent in the PL spectra of nanocomposite films heated at 100,°C for 7,h in air with direct excitation of the keto defect. Finally, no green emission was observed in the electroluminescence spectrum of light-emitting devices fabricated with a polymer-intercalated SnS2 nanocomposite film. These results support the proposed hypothesis that fluorenone defects alone are insufficient to generate the green emission and that interchain interactions are also required. [source] Electrochemical Preparation and Characterization of Lanthanum Hexacyanoferrate Modified ElectrodeCHINESE JOURNAL OF CHEMISTRY, Issue 2 2005Wu Ping Abstract An electroactive polynuclear inorganic compound of rare earth metal hexacyanoferrate, lanthanum hexacyanoferrate (LaHCF), was prepared by electrochemical deposition on the surface of a glassy carbon electrode with a potential cycling procedure. The cyclic voltammogram of LaHCF exhibits a pair of well-defined redox peaks with the formal potential of 208 mV (vs. SCE) at a scan rate of 100 mV/s in 0.2 mol/L NaCl solution and the redox peak currents increase linearly with the square root of the scan rate up to 1000 mV/s. The effects of the concentration of supporting electrolyte on the electrochemical characteristics of LaHCF were studied by voltammetry. LaHCF was also characterizated by scanning electron microscope (SEM), FTIR and XPS techniques. [source] Structural and spectroscopic study of Mg13.4(OH)6(HVO4)2(H0.2VO4)6CRYSTAL RESEARCH AND TECHNOLOGY, Issue 11 2008Abstract Single-crystals of the polar compound magnesium hydrogen vanadate(V), Mg13.4(OH)6(HVO4)2(H0.2VO4)6, were synthesized hydrothermally. It represents the first hydrogen vanadate(V) among inorganic compounds. Its structure was determined by single-crystal X-ray diffraction [space group P 63mc, a = 12.9096(2), c = 5.0755(1) Å, V = 732.55(2) ų, Z = 1]. The crystal structure of Mg13.4(OH)6(HVO4)2(H0.2VO4)6 consists of well separated, vacancy-interrupted chains of face sharing Mg2O6 octahedra, with short Mg2,Mg2 distances of 2.537(1) Å, embedded in a porous magnesium vanadate 3D framework having the topology of the zeolite cancrinite. All three hydrogen positions in the structure were confirmed by FTIR spectroscopy. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A study of primary nucleation of calcium oxalate monohydrate: II.CRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2004Effect of urinary species Abstract Kidney stones consist of various organic and inorganic compounds. Calcium oxalate monohydrate (COM) is the main inorganic constituent of kidney stones. However, the mechanisms for the formation of calcium oxalate kidney stones are not well understood. In this regard, there are several hypotheses including nucleation, crystal growth and/or aggregation of formed COM crystals. The effect of some urinary species such as oxalate, calcium, citrate, and protein on nucleation and crystallization characteristics of COM is determined by measuring the weight of formed crystals and their size distributions under different chemical conditions, which simulate the urinary environment. Statistical experimental designs are used to determine the interaction effects among various factors. The data clearly show that oxalate and calcium promote nucleation and crystallization of COM. This is attributed to formation of a thermodynamically stable calcium oxalate monohydrate resulting from supersaturation. Citrate, however, inhibits nucleation and further crystal growth. These results are explained on the basis of the high affinity of citrate to combine with calcium to form soluble calcium citrate complexes. Thus, citrate competes with oxalate ion for binding to calcium cations. These conditions decrease the amount of free calcium ions available to form calcium oxalate crystals. In case of protein (mucin), however, the results suggest that no significant effect could be measured of mucin on nucleation and crystal growth. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nutrient limitations during the biofiltration of methyl isoamyl ketoneENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2005Hyun-Keun Son With biofiltration, both organic and inorganic compounds that are toxic to humans and volatile organic compounds from a variety of industrial and public sector sources have been effectively removed. During the initial stage of the acclimation period, the removal capacity of the biofilter is primarily attributed to the adsorption capacity of the media. The adsorption capacity of different types of biofilter media was studied. MIAK (methyl isoamyl ketone), which is one of the major air pollutants in painting operations, was used as the target air pollutant for the biofiltration experiments. All the materials tested exhibited very poor adsorption capacity for MIAK. The effect of nutrient limitation was also evaluated. A gradual decrease of removal capacity was observed under the nutrient-limited environment. When nutrient was provided to the biofilter, the removal capacity increased from 55 to 93% in 3 days. A nutrient ratio of chemical oxygen demand (COD):N:P = 200:4:1 was sufficient for the removal of volatile organic compounds from the polluted air stream. © 2004 American Institute of Chemical Engineers Environ Prog, 2004 [source] Synthesis and Characterisation of a New Cu(O2CNAllyl2)2 Carbamato Complex and an Unusual Polymeric CuI Complex [CuI4Cl4(NHAllyl2)4]n: New Insights into Metal Carbamato ChemistryEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 35 2009Alberto Albinati Abstract Transition-metal N,N -dialkylcarbamato complexes represent an interesting class of compounds that can be conveniently used as precursors for the controlled formation of inorganic compounds, typically oxides. They can also be used as convenient precursors for chemical grafting of metal oxides on oxide surfaces as well as for the synthesis of inorganic,organic hybrid materials. In this last case, the presence of double bonds on the complex would enable its covalent embedding into a polymer matrix through reaction with suitable monomers. To this aim, we addressed the synthesis of an allyl-functionalised copper carbamato complex. During the synthesis of the N,N -diallylcarbamato complex Cu(O2CNAllyl2)2 (Cu1), the formation of the crystalline and unusual polymeric CuI complex [CuI4Cl4(NHAllyl2)4]n (Cu2) was observed. The new compound was characterised by X-ray single crystal diffraction and FTIR, 1H and 13C NMR spectroscopic analysis. In an attempt to investigate the redox mechanism and the equilibria leading to the formation of the observed unusual CuI polymeric complex, gas chromatography coupled with mass spectrometry (GC,MS) experiments were carried out, which allowed us to identify 3,4-dimethylpyrrole as the oxidation product of the reaction, leading to the reduction of CuII to CuI.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Comparative Sol,Hydro(Solvo)thermal Synthesis of TiO2 NanocrystalsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2006Xianfeng Yang Abstract Three small inorganic compounds [acetic acid (CH3COOH), nitric acid (HNO3), and hydrochloric acid (HCl)] andfive small organic compounds [n -butyl alcohol (CH3CH2CH2CH2OH), 1,2-propanediol (CH2OHCHOHCH3), propane-1,3-dicarboxylic acid (HOOCCH2COOH), butane-1,4-dicarboxylic acid (HOOCCH2CH2COOH), and ethylenediamine (H2NCH2CH2NH2)] with different donors (Cl,, NO3,, OH, COO,, and NH2) are used respectively and comparatively in different reaction media for tailoring the sol,hydrothermal synthesis of TiO2 nanocrystals at a specific reaction temperature and/or for different reaction times. Both anatase and rutile with a variety of nanostructures such as nanocubes, nanorods, nanoneedles, and their self-assembled nanospheres are selectively grown. Well-defined and crystalline anatase nanocrystals with a narrow size distribution are prepared in the presence of n -butyl alcohol. With the use of HCl, nanoneedles and their assembled nanospheres of phase-pure rutile are obtained under much less drastic conditions, even at 100 °C and for only two hours. The effects of the reaction media, synthesis temperatures, and aging times on the structures and shapes of the products are investigated in detail by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Bacterial community analysis of shallow groundwater undergoing sequential anaerobic and aerobic chloroethene biotransformationFEMS MICROBIOLOGY ECOLOGY, Issue 2 2007Todd R. Miller Abstract At Department of Energy Site 300, beneficial hydrocarbon cocontaminants and favorable subsurface conditions facilitate sequential reductive dechlorination of trichloroethene (TCE) and rapid oxidation of the resultant cis- dichloroethene (cis -DCE) upon periodic oxygen influx. We assessed the geochemistry and microbial community of groundwater from across the site. Removal of cis -DCE was shown to coincide with oxygen influx in hydrocarbon-containing groundwater near the source area. Principal component analysis of contaminants and inorganic compounds showed that monitoring wells could be differentiated based upon concentrations of TCE, cis -DCE, and nitrate. Structurally similar communities were detected in groundwater from wells containing cis -DCE, high TCE, and low nitrate levels. Bacteria identified by sequencing 16S rRNA genes belonged to seven phylogenetic groups, including Alpha -, Beta -, Gamma - and Deltaproteobacteria, Nitrospira, Firmicutes and Cytophaga,Flexibacter,Bacteroidetes (CFB). Whereas members of the Burkholderiales and CFB group were abundant in all wells (104,109 16S rRNA gene copies L,1), quantitative PCR showed that Alphaproteobacteria were elevated (>106 L,1) only in wells containing hydrocarbon cocontaminants. The study shows that bacterial community structure is related to groundwater geochemistry and that Alphaproteobacteria are enriched in locales where cis -DCE removal occurs. [source] Research on Advanced Materials for Li-ion BatteriesADVANCED MATERIALS, Issue 45 2009Hong Li Abstract In order to address power and energy demands of mobile electronics and electric cars, Li-ion technology is urgently being optimized by using alternative materials. This article presents a review of our recent progress dedicated to the anode and cathode materials that have the potential to fulfil the crucial factors of cost, safety, lifetime, durability, power density, and energy density. Nanostructured inorganic compounds have been extensively investigated. Size effects revealed in the storage of lithium through micropores (hard carbon spheres), alloys (Si, SnSb), and conversion reactions (Cr2O3, MnO) are studied. The formation of nano/micro core,shell, dispersed composite, and surface pinning structures can improve their cycling performance. Surface coating on LiCoO2 and LiMn2O4 was found to be an effective way to enhance their thermal and chemical stability and the mechanisms are discussed. Theoretical simulations and experiments on LiFePO4 reveal that alkali metal ions and nitrogen doping into the LiFePO4 lattice are possible approaches to increase its electronic conductivity and does not block transport of lithium ion along the 1D channel. [source] Solution Processing of Chalcogenide Semiconductors via Dimensional ReductionADVANCED MATERIALS, Issue 31 2009David B. Mitzi Abstract The quest to develop thin-film solution processing approaches that offer low-cost and preferably low-temperature deposition, while simultaneously providing quality semiconductor characteristics, has become an important thrust within the materials community. While inorganic compounds offer the potential for outstanding electronic properties relative to organic systems, the very nature of these materials rendering them good electronic materials,namely strong covalent bonding,also leads to poor solubility. This review presents a "dimensional reduction" approach to improving the solubility of metal chalcogenide semiconductors, which generally involves breaking the extended framework up into discrete metal chalcogenide anions separated by small and volatile cationic species. The resulting soluble precursor may be solution-processed into thin-film form and thermally decomposed to yield the desired semiconductor. Several applications of this principle to the solution deposition of high-performance active layers for transistors (channel mobility >10,cm2 V,1 s,1), solar cells (power conversion efficiency of as high as 12%), and fundamental materials study will be presented using hydrazine as the deposition solvent. [source] CLARIFICATION AND PURIFICATION OF AQUEOUS STEVIA EXTRACT USING MEMBRANE SEPARATION PROCESSJOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2009M.H.M. REIS ABSTRACT Stevia rebaudiana Bertoni is a native plant from South America and its active constituents have been considered the "sweeteners of the future."Stevia is a natural diet-sweetening source, safe to health and without calories. However, the obtained raw extract is foul smelling, bitter tasting, dark brown colored, and presents suspension matter due to organic and inorganic compounds. Therefore, further purification/clarification is essential in order to get a product of commercial quality. In this work ceramic membranes were applied in the stevia extract clarification process. The process was carried out under different membrane pore sizes and at different pressure values. The best clarification result was obtained with the membrane of 0.1 µm at 4 bar. On the other hand, the best condition for the flux was obtained with the membrane of 0.2 µm at 6 bar. The process with all the tested membranes and conditions achieved recovery of sweeteners higher than 90%. Finally, a filtration mathematical model was applied to describe the flux behavior, showing that the main fouling phenomenon during the process occurred because of the complete blocking of pores. PRACTICAL APPLICATION Stevia is the world's only all-natural sweetener with zero calories, zero carbohydrates and a zero glycemic index. However, the obtained stevia extract has a dark brown appearance, mainly because of the presence of impurities. In this work the membrane separation process was studied for stevia extract clarification and purification in order to get a product with higher commercial acceptability. The obtained results showed that total clarification and recuperation of sweeteners was almost achieved. Nonetheless, membrane fouling is an inevitable problem during membrane filtration. The mathematical analysis of the fouling occurrences showed that the complete blocking of pores is the main cause for the membrane permeability decrease. [source] SUPERCRITICAL CARBON DIOXIDE TREATMENT TO INACTIVATE AEROBIC MICROORGANISMS ON ALFALFA SEEDSJOURNAL OF FOOD SAFETY, Issue 4 2001ANGELA M. MAZZONI ABSTRACT The supercritical carbon dioxide (SC-CO2) process involves pressurizing CO2 in a chamber which generates liquid phase of carbon dioxide. Pressurized liquid CO2 has a strong extraction capability of organic and inorganic compounds. The recent studies have also demonstrated that antimicrobial effect of SC-CO2 due extraction some cellular components of microorganisms. The efficacy of a supercritical carbon dioxide treatment on alfalfa seeds contaminated with Escherichia coli K12 was tested at 2000, 3000, and 4000 psi at 50C. Samples were treated for 15, 30, and 60 min at each pressure. After pummeling the seed samples in 0.1% peptone water, the initial and final Escherichia coli and total aerobic bacteria on the seeds were determined by plating on 3M Petri Films. After 48 h of incubation at 37 C, the colonies were enumerated. Treated seeds were evaluated in terms of germination characteristics. For aerobic plate count, the effect of pressure in the range of 2000,4000 psi was not statistically significant (p > 0.05) even though 85.6% inactivation was achieved at 4000 psi for 60 min. For E. coli, the reductions for 2000, 3000, and 4000 psi treatments for 15 min were 26.6, 68.1, and 81.3%, respectively. As the time was increased from 15 to 60 min at 4000 psi, the percent E. coli reduction increased from 81.3% to 92.8%. The percent germination for all treatments was over 90%. There was no significant difference (p > 0.05) in the germination rate of treated and untreated seeds. Supercritical carbon dioxide treatments demonstrated a reduction of E. coli K12 and total aerobic counts without affecting the germination characteristics of alfalfa seeds (p < 0.05). This study was a step in the direction of improving safety of alfalfa seeds used to produce fresh sprouts, which have been the cause of several outbreaks. [source] Thermodynamic modeling of hydrotrope solutionsAICHE JOURNAL, Issue 1 2006Mandana Akia Abstract A new model for the excess Gibbs energy of hydrotrope solutions is presented. This model is based on the local composition model by Chen et al. Hydrotropes are usually organic salts that can increase the solubility of organic and inorganic compounds in water. The proposed model has five adjustable parameters; one of them is related to long-range forces, and four of them are related to short-range forces. Long-range forces are modeled by the Pitzer-Debye-Huckel equation. However, in our model, the effect of the molecular solute on the dielectric constant of water has also been considered. Modeling of short-range forces is based on local composition concepts. The model parameters are obtained using experimental data for six hydrotropes with four solutes at different temperatures. The water solubility of molecular solutes in the presence of hydrotropes has been calculated for different systems. Accurate results are obtained. © 2005 American Institute of Chemical Engineers AIChE J, 2006 [source] A data base for partition of volatile organic compounds and drugs from blood/plasma/serum to brain, and an LFER analysis of the dataJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2006Michael H. Abraham Abstract Literature values of the in vivo distribution (BB) of drugs from blood, plasma, or serum to rat brain have been assembled for 207 compounds (233 data points). We find that data on in vivo distribution from blood, plasma, and serum to rat brain can all be combined. Application of our general linear free energy relationship (LFER) to the 207 compounds yields an equation in log BB, with R2,=,0.75 and a standard deviation, SD, of 0.33 log units. An equation for a training set predicts the test set of data with a standard deviation of 0.31 log units. We further find that the invivo data cannot simply be combined with in vitro data on volatile organic and inorganic compounds, because there is a systematic difference between the two sets of data. Use of an indicator variable allows the two sets to be combined, leading to a LFER equation for 302 compounds (328 data points) with R2,=,0.75 and SD,=,0.30 log units. A training equation was then used to predict a test set with SD,=,0.25 log units. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:2091,2100, 2006 [source] Plate-out in PVC extrusion.JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 1 2008Samples of extruder plate-out from industrial rigid PVC production lines were investigated by using a number of analytical techniques. The combined use of SEM-EDX (scanning electron microscopy , energy dispersive X-ray analysis), thermal analysis, FTIR (Fourier transform infrared spectrophotometry), and LIMA (laser-induced mass analysis) enabled most plate-out components to be identified and linked to likely formulation ingredients. The FTIR and thermal analyses were used to identify organic components. The FTIR analysis was also useful for identifying some inorganic compounds present in sufficient quantities, while EDX detected the elements present. The LIMA was the most sensitive technique, detecting trace quantities of both cations and anions. Calcium carbonate, titanium dioxide, and lead stabilizers were found in all die plate-out samples studied, together with small amounts of lubricants. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers. [source] Nanostructured polyolefins/clay composites: role of the molecular interaction at the interfacePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2008Elisa Passaglia Abstract The extent of interphase interactions between polymer phase and inorganic particles is the driving force addressing the preparation/properties design in the field of the corresponding micro- and nanocomposites. In the case of preparation of nanocomposites based on polyolefins (POs) and inorganic compounds as potentially nanodispersed phase, the use of a PO with proper functional groups is necessary for the interface adhesion and stabilization of the nanostructured morphology. According to this approach, ethylene/propylene copolymers with a different propylene content were used for the preparation of nanocomposites through melt mixing with organophilic montmorillonites (OMMT). By taking into account the important role of functionalities grafted onto POs, two different synthetic approaches were compared here: (1) the dispersion of the inorganic filler was obtained by using previously functionalized POs bearing carboxylate groups as matrices; (2) the nanocomposites were prepared by performing contemporaneously the functionalization of POs (by using maleic anhydride (MAH) and/or diethyl maleate (DEM)) and the dispersion of the filler in a one-step process. The morphology of the nanocomposites as well as the variation of solubility and glass transition temperature (Tg) of the PO matrix were evaluated and tentatively discussed with reference to functionalization degrees, structure of PO, and preparation procedure. Copyright © 2008 John Wiley & Sons, Ltd. [source] BaY2Si3O10: a new flux-grown trisilicateACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2006Uwe Kolitsch BaY2Si3O10, barium diyttrium trisilicate, is a new silicate grown from a molybdate-based flux. The structure is based on zigzag chains, parallel to [010], of edge-sharing distorted YO6 octahedra, linked by horseshoe-shaped trisilicate groups and Ba atoms in irregular eight-coordination. The layered character of the structure is caused by a succession of zigzag chains and trisilicate groups in planes parallel to (01). The Ba atoms occupy narrow channels extending parallel to [100]. The mean Y,O, Si,O and Ba,O bond lengths are 2.268, 1.626 and 1.633, and 2.872,Å, respectively. The two symmetry-equivalent terminal SiO4 tetrahedra in the Si3O10 unit adopt an eclipsed conformation with respect to the central SiO4 tetrahedron; the Si,O,Si and Si,Si,Si angles are 136.35,(9) and 96.12,(4)°, respectively. One Ba, one Si and two O atoms are located on mirror planes; all remaining atoms are in general positions. The geometry of isolated trisilicate groups in inorganic compounds is briefly discussed. [source] Study of factors affecting binding of zinc with albumin at physiological zinc concentrationsBIOFACTORS, Issue 3 2004V.V. Agte Abstract Albumin has very high affinity for many organic and inorganic compounds that may influence albumin bound Zn (ABZn). To get insight of these molecular interactions, the effect of riboflavin, nicotinic acid, thiamine, folic acid, pyruvic acid and glucose on ABZn were studied. The ABZn was separated from the unbound zinc using equilibrium dialysis and estimated using atomic absorption spectrometer. At therapeutic zinc concentrations, folic acid and thiamine significantly enhanced the ABZn (p < 0.010), while nicotinic acid inhibited zinc binding to albumin. Folic acid was found to enhance the ABZn also at lower zinc concentrations representing physiological levels of plasma zinc (138,150 micromoles) (p < 0.05). [source] Progress technology in microencapsulation methods for cell therapyBIOTECHNOLOGY PROGRESS, Issue 4 2009Jean-Michel Rabanel Abstract Cell encapsulation in microcapsules allows the in situ delivery of secreted proteins to treat different pathological conditions. Spherical microcapsules offer optimal surface-to-volume ratio for protein and nutrient diffusion, and thus, cell viability. This technology permits cell survival along with protein secretion activity upon appropriate host stimuli without the deleterious effects of immunosuppressant drugs. Microcapsules can be classified in 3 categories: matrix-core/shell microcapsules, liquid-core/shell microcapsules, and cells-core/shell microcapsules (or conformal coating). Many preparation techniques using natural or synthetic polymers as well as inorganic compounds have been reported. Matrix-core/shell microcapsules in which cells are hydrogel-embedded, exemplified by alginates capsule, is by far the most studied method. Numerous refinement of the technique have been proposed over the years such as better material characterization and purification, improvements in microbead generation methods, and new microbeads coating techniques. Other approaches, based on liquid-core capsules showed improved protein production and increased cell survival. But aside those more traditional techniques, new techniques are emerging in response to shortcomings of existing methods. More recently, direct cell aggregate coating have been proposed to minimize membrane thickness and implants size. Microcapsule performances are largely dictated by the physicochemical properties of the materials and the preparation techniques employed. Despite numerous promising pre-clinical results, at the present time each methods proposed need further improvements before reaching the clinical phase. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] Quantum Dots Arrangement and Energy Transfer Control via Charge-Transfer Complex Achieved on Poly(Phenylene Ethynylene)/Schizophyllan NanowiresCHEMISTRY - AN ASIAN JOURNAL, Issue 9 2009Tomohiro Shiraki Abstract Assemblies of organic and inorganic compounds in the nanoscale region have contributed to the development of novel functional materials toward future applications, including sensors and opto-electronics. We succeed in fabricating hybrid nanowires composed of a conjugated polymer and semiconductor quantum dots (QDs) by a supramolecular assembly technique. The 1-D fashion of the nanowire structure is obtained by the polymer wrapping of cationic poly(phenylene ethynylene) (PPE) with helix-forming polysaccharide schizophyllan (SPG). The electrostatic interaction between cationic PPE and anionic QDs affords the nanowires decorated with QDs. Upon addition of an acceptor molecule, tetranitrofluorenone (TNF), the charge-transfer (CT) complex between PPE and TNF is formed, resulting in energy transfer from the QDs to PPE arising from the induced spectral overlap. Furthermore, the employment of the conjugated polymer allows highly sensitive quenching of the QD's emission by raising the transmission efficiency to the CT complexed electron deficient sites along the polymer backbone. [source] Structural determinations by circular dichroism spectra analysis using coupled oscillator methods: An update of the applications of the DeVoe polarizability model,CHIRALITY, Issue 7 2004Stefano Superchi Abstract The exciton (coupled oscillator) model for optical activity is a very useful and powerful method which allows to analyze a circular dichroism (CD) spectrum in a nonempirical way, arriving at a safe assignment of the absolute configuration of organic and inorganic compounds. Usually in this model only the exciton coupling of two electrically allowed transitions (oscillators) is taken into account. This approach has the important advantage of an easy application but, sometimes, it may lead to wrong results. Thus, in this review article a more general treatment, which allows considering the simultaneous coupling of several oscillators, i.e., the DeVoe model, is presented and critically analyzed, discussing in detail the latest applications reported in the literature. In the authors opinion, since the DeVoe model joins generality and reliability requiring an almost negligible computational effort, it represents the method of choice for stereochemical assignments, even by nonspecialists. Chirality 16:422,451, 2004. © 2004 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||