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Direct Formation (direct + formation)
Selected AbstractsDirect Formation of Crystalline Gadolinium-Doped Ceria Powder via Polymerized Precursor SolutionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2002Shuqiang Wang Synthesis of Ce0.9Gd0.1O1.95 (CGO) powder from a polymeric precursor solution containing a mixture of nitrates, nitric acid, and ethylene glycol was investigated with emphasis on the effect of polymerization of the precursor solution on the crystallization and morphology of the derived solid intermediate and the final oxide powder. It is shown for the first time in this work that the solid intermediate derived from the polymerized solution is present in the form of well-crystallized cerium-gadolinium formate solid solution, Ce1,xGdx(HCOO)3, exhibiting anisotropic growth. Further polymerization of the precursor solution resulted in the direct formation of loosely agglomerated nanoscaled CGO oxide powder from the polymerized solution at temperatures as low as 130°C. [source] Photooxidation of Nanopatterned Poly(chloromethylstyrene): Direct Formation of Crosslinked Aldehyde-Functionalized Films for Chemical Functionalization and BioconjugationMACROMOLECULAR RAPID COMMUNICATIONS, Issue 9-10 2010Xi Yu Abstract UV irradiation of chloromethyl styrene simultaneously crosslinks the polymer and generates aldehyde groups that can be employed for polymer surface functionalization through aldehyde-imine/hydrazone chemistry. Using this method, we successfully have functionalized nanoimprinted polymer patterns with dyes, nanoparticles, and enzymes. These surfaces were characterized by infrared (ATR-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), fluorescence microscopy, and enzymatic activity assays. [source] Direct Formation of Mesoporous Coesite Single Crystals from Periodic Mesoporous Silica at Extreme Pressure,ANGEWANDTE CHEMIE, Issue 25 2010Paritosh Mohanty Dr. Unter extremem Druck, bei 12,GPa, gelingt die Titelreaktion ohne Templatzusatz. Aus SBA-16 entstehen so einkristalline Coesit-Partikel mit Porengrößen um 4,nm und ungefähr 50,% Porosität. Diese Reaktion lässt sich mit der kinetisch gesteuerten Kristallisation eines nichtporösen, elastisch verformten und glasartigen Siliciumdioxid-Intermediat erklären (siehe Schema). [source] ChemInform Abstract: Direct Formation of Cyclobutenylphosphonates from 1-Alkynylphosphonates and Cp2ZrCl2/2EtMgCl/2CuCl.CHEMINFORM, Issue 21 2009Yulia Sinelnikove 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Stereo- and Regiospecific Four-Molecule Reaction of Aroyl Chlorides with iso-Pentylene: Direct Formation of (E)-,,,-Unsaturated Carbonyl Compounds Promoted by Samarium Metal in DMF.CHEMINFORM, Issue 19 2004Yongjun Liu Abstract For Abstract see ChemInform Abstract in Full Text. [source] Application of New Organic Fuels in the Direct MgAl2O4 Combustion SynthesisEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2008Robert Iano Abstract The paper presents a new version of MgAl2O4 solution-combustion synthesis, based on the individual reactivity of Mg(NO3)2 and Al(NO3)3 with respect to various fuels. Beside the traditionally used fuels (urea, glycine, ,-alanine), new organic reducing agents [monoethanolamine, triethanolamine, tris(hydroxymethyl)aminomethane and triethylenetetramine] have also been used. The study of the individual reactivities of Mg(NO3)2 and Al(NO3)3 with respect to each of the previously mentioned fuels suggested that there is a predilection of the two metal nitrates for certain fuels: urea is the optimum fuel for Al(NO3)3, whereas monoethanolamine represents the most suitable fuel for Mg(NO3)2. It has been shown by X-ray diffraction and thermal analysis that the use of a single fuel in the MgAl2O4 low-temperature combustion synthesis leads to the formation of an amorphous powder. In this case, the formation of pure crystalline MgAl2O4 requires a subsequent thermal treatment at 900 °C with 1 h soaking time. On the other hand, the use of fuel mixtures containing urea and monoethanolamine or urea and ,-alanine proved to be the rational solution for the direct formation of MgAl2O4. It has been shown that, by using the above-mentioned fuel mixtures, one can obtain pure nanocrystalline MgAl2O4 straight from the combustion reaction, no additional calcination being necessary. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Formation of Nanoislands on Conducting Poly(3,4-ethylenedioxythiophene) Films by High-Energy - Ion Irradiation: Applications as Field Emitters and Capacitor Electrodes,ADVANCED FUNCTIONAL MATERIALS, Issue 9 2005J. Joo Abstract Nanoislands have been fabricated on the surface of conducting poly(3,4-ethylenedioxythiophene) (PEDOT) films doped with poly(4-styrenesulfonate) (PSS) using high-energy (,,1,3,MeV) Cl2+ ion irradiation. Scanning electron microscopy and atomic force microscopy confirm the direct formation of nanoislands with diameters ranging from 50,to 300,nm and heights ranging from 40,to 120,nm. From our analysis, we propose that the formation of nanoislands might be due to micelle formation of the polymeric stabilizer poly(sodium 4-styrenesulfonate) (PSS-Na) surrounding the nuclei in the PEDOT/PSS via the high-energy-ion irradiation. We observe similar results for high-energy-ion irradiated polyaniline doped with PSS-Na. On using the nanoislands as nanotip emitters of a field-emission display, an increase in the current density of about five orders of magnitude is observed. Cyclic voltammetry of the PEDOT/PSS electrode with the nanoislands as the electrode shows enhanced capacitance compared with that of the PEDOT/PSS film that contains no nanostructure. [source] The effect of Emdogain® on the growth and differentiation of rat bone marrow cellsJOURNAL OF PERIODONTAL RESEARCH, Issue 5 2006J. Van Den Dolder Background and Objective:, The major extracellular matrix (ECM) proteins in developing enamel can induce and maintain the formation and mineralization of other skeletal hard tissue, such as bone. Therefore, dental matrix proteins are ideal therapeutic agents when direct formation of functional bone is required for a successful clinical outcome. Emdogain® (EMD) consists of enamel matrix proteins which are known to stimulate bone formation. However, only a few studies in the literature have reported the effect of EMD on osteoblast-like cells in vitro. Material and Methods:, In this study, rat bone marrow cells, obtained from the femora of Wistar rats, were precultured for 7 d in osteogenic medium. Then, the cells were harvested and seeded in 24-well plates at a concentration of 20,000 cells/well. The wells were either precoated with 100 µg/ml EMD, or left uncoated. The seeded cells were cultured in osteogenic medium for 32 d and analysed for cell attachment (by using the Live and Dead assay), cell growth (by determining DNA content) and cell differentiation (by measuring alkaline phosphatase activity and calcium content, and by using scanning electron microscopy and the reverse transcription,polymerase chain reaction). Results:, The results showed that at the 4-h time point of the experiment, more cells were attached to EMD-negative wells, but this effect was no longer apparent at 24 h. DNA analysis revealed that both groups showed a similar linear trend of cell growth. No differences in alkaline phosphatase activity or calcium content were observed, and no differences in gene expression (osteocalcin, alkaline phosphatase and collagen type I) were found between the groups. Conclusion:, Based on our results, we conclude that EMD had no significant effect on the cell growth and differentiation of rat bone marrow cells. [source] Direct Formation of Crystalline Gadolinium-Doped Ceria Powder via Polymerized Precursor SolutionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2002Shuqiang Wang Synthesis of Ce0.9Gd0.1O1.95 (CGO) powder from a polymeric precursor solution containing a mixture of nitrates, nitric acid, and ethylene glycol was investigated with emphasis on the effect of polymerization of the precursor solution on the crystallization and morphology of the derived solid intermediate and the final oxide powder. It is shown for the first time in this work that the solid intermediate derived from the polymerized solution is present in the form of well-crystallized cerium-gadolinium formate solid solution, Ce1,xGdx(HCOO)3, exhibiting anisotropic growth. Further polymerization of the precursor solution resulted in the direct formation of loosely agglomerated nanoscaled CGO oxide powder from the polymerized solution at temperatures as low as 130°C. [source] Alteration of the disulfide-coupled folding pathway of BPTI by circular permutationPROTEIN SCIENCE, Issue 5 2004Grzegorz Bulaj BPTI, bovine pancreatic trypsin inhibitor; cBPTI, a circular form of BPTI generated by forming a peptide bond between the natural termini; cpBPTI, circularly permuted BPTI. Abstract The kinetics of disulfide-coupled folding and unfolding of four circularly permuted forms of bovine pancreatic trypsin inhibitor (BPTI) were studied and compared with previously published results for both wild-type BPTI and a cyclized form. Each of the permuted proteins was found to be less stable than either the wild-type or circular proteins, by 3,8 kcal/mole. These stability differences were used to estimate effective concentrations of the chain termini in the native proteins, which were 1 mM for the wild-type protein and 2.5 to 4000 M for the permuted forms. The circular permutations increased the rates of unfolding and caused a variety of effects on the kinetics of refolding. For two of the proteins, the rates of a direct disulfide-formation pathway were dramatically increased, making this process as fast or faster than the competing disulfide rearrangement mechanism that predominates in the folding of the wild-type protein. These two permutations break the covalent connectivity among the ,-strands of the native protein, and removal of these constraints appears to facilitate direct formation and reduction of nearby disulfides that are buried in the folded structure. The effects on folding kinetics and mechanism do not appear to be correlated with relative contact order, a measure of overall topological complexity. These observations are consistent with the results of other recent experimental and computational studies suggesting that circular permutation may generally influence folding mechanisms by favoring or disfavoring specific interactions that promote alternative pathways, rather than through effects on the overall topology of the native protein. [source] Noncovalent Assembly of Picket-Fence Porphyrins on Nitrogen-Doped Carbon Nanotubes for Highly Efficient Catalysis and BiosensingCHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2010Wenwen Tu Abstract A water-insoluble picket-fence porphyrin was first assembled on nitrogen-doped multiwalled carbon nanotubes (CNx MWNTs) through FeN coordination for highly efficient catalysis and biosensing. Scanning electron micrographs, Raman spectra, X-ray photoelectron spectra, UV/Vis absorption spectra, and electrochemical impedance spectra were employed to characterize this novel nanocomposite. By using electrochemical methods on the porphyrin at low potential in neutral aqueous solution, the presence of CNx MWNTs led to the direct formation of a high-valent iron(IV),porphyrin unit, which produced excellent catalytic activity toward the oxidation of sulfite ions. By using sulfite ions, a widely used versatile additive and preservative in the food and beverage industries, as a model, a highly sensitive amperometric biosensor was proposed. The biosensor showed a linear range of four orders of magnitude from 8.0×10,7 to 4.9×10,3,mol,L,1 and a detection limit of 3.5×10,7,mol,L,1 due to the highly efficient catalysis of the nanocomposite. The designed platform and method had good analytical performance and could be successfully applied in the determination of sulfite ions in beverages. The direct noncovalent assembly of porphyrin on CNx MWNTs provided a facile way to design novel biofunctional materials for biosensing and photovoltaic devices. [source] | |||||||||||||