Controlled hydrolysis of aryltellurium trichlorides using 2-pyrrolidinones: isolation and structural characterization of monomeric aryltellurium(IV) monohydroxides

RSC Advances ◽  
2011 ◽  
Vol 1 (5) ◽  
pp. 808 ◽  
Author(s):  
Shafalika Misra ◽  
Ashok K. S. Chauhan ◽  
Ramesh C. Srivastava ◽  
Andrew Duthie ◽  
R. J. Butcher
Keyword(s):  
Structural Characterization ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis

scholarly journals Characterization of Glycoside Hydrolase Family 5 Proteins in Schizosaccharomyces pombe

2010 ◽  
Vol 9 (11) ◽  
pp. 1650-1660 ◽  
Author(s):  
Encarnación Dueñas-Santero ◽  
Ana Belén Martín-Cuadrado ◽  
Thierry Fontaine ◽  
Jean-Paul Latgé ◽  
Francisco del Rey ◽  
...  
Keyword(s):  
Cell Wall ◽  
Schizosaccharomyces Pombe ◽  
Protein Characterization ◽  
Wall Material ◽  
Glycoside Hydrolase Family ◽  
Content Type ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis ◽  
Hydrolase Family

ABSTRACT In yeast, enzymes with β-glucanase activity are thought to be necessary in morphogenetic events that require controlled hydrolysis of the cell wall. Comparison of the sequence of the Saccharomyces cerevisiae exo-β(1,3)-glucanase Exg1 with the Schizosaccharomyces pombe genome allowed the identification of three genes that were named exg1 + (locus SPBC1105.05), exg2 + (SPAC12B10.11), and exg3 + (SPBC2D10.05). The three proteins have different localizations: Exg1 is secreted to the periplasmic space, Exg2 is a membrane protein, and Exg3 is a cytoplasmic protein. Characterization of the biochemical activity of the proteins indicated that Exg1 and Exg3 are active only against β(1,6)-glucans while no activity was detected for Exg2. Interestingly, Exg1 cleaves the glucans with an endohydrolytic mode of action. exg1 + showed periodic expression during the cell cycle, with a maximum coinciding with the septation process, and its expression was dependent on the transcription factor Sep1. The Exg1 protein localizes to the septum region in a pattern that was different from that of the endo-β(1,3)-glucanase Eng1. Overexpression of Exg2 resulted in an increase in cell wall material at the poles and in the septum, but the putative catalytic activity of the protein was not required for this effect.

Preparation and Characterization of Y3Al5O12 (YAG) from An Alkoxide-Derived Polymer

1992 ◽  
Vol 286 ◽  
Author(s):  
Zhiping Jiang ◽  
Wendell E. Rhine
Keyword(s):  
Infrared Spectroscopy ◽  
Yttrium Aluminum Garnet ◽  
Polymeric Materials ◽  
Pyrolysis Products ◽  
Elemental Analyses ◽  
Yttrium Aluminum ◽  
Ft Ir ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis

ABSTRACTThe controlled hydrolysis of Al(O-sec-Bu)3 and Y(O-iso-Pr)3 or the reaction of Y(OOCCH)3 with partially hydrolyzed Al(O-sec-Bu)3 [AlO0.75(O-sec-Bu)1.5] resulted in the formation of soluble polymeric materials. Pyrolysis of these materials under a flow of oxygen led to the formation of yttrium aluminum garnet (YAG) at 650-1500°C. YAG was the only crystalline phase observed during pyrolysis, and the Al/Y ratio of the pyrolysis products and the starting material was identical. However, infrared spectroscopy indicated that carbonate groups and entrained CO2 existed in the products at temperatures up to 1250°C. The pyrolysis chemistry of the precursors and the microstructure of the products were studied by FT-IR, TGA, XRD, SEM and elemental analyses.

Synthesis and Structural Characterization of a Terminal Hydroxide Containing Alumoxane via Hydrolysis of Aluminum Hydrides

2004 ◽  
Vol 43 (4) ◽  
pp. 1217-1219 ◽  
Author(s):  
Ying Peng ◽  
Guangcai Bai ◽  
Hongjun Fan ◽  
Denis Vidovic ◽  
Herbert W. Roesky ◽  
...  
Keyword(s):  
Structural Characterization ◽  
Aluminum Hydrides ◽  
Hydrolysis Of

Preparation and Electrophoretic Deposition of an Yttrium Silicate Precursor Sol

2009 ◽  
Vol 412 ◽  
pp. 267-272 ◽  
Author(s):  
Jana Grosse-Brauckmann ◽  
Günter Borchardt ◽  
Christos Argirusis
Keyword(s):  
Electrophoretic Deposition ◽  
Sol Gel ◽  
Constant Current ◽  
Particle Charge ◽  
Yttrium Silicate ◽  
Micro Cracks ◽  
Sol Gel Process ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis

. In the present work we used the sol-gel process to prepare Y2SiO5 precursor sols suitable for electrophoretic deposition (EPD). The sol synthesis was performed through the controlled hydrolysis of alkoxide solutions of tetraethoxysilane and yttriumoxoisopropoxide. During sol development emphasis was put on characterization of particles size and zeta potential of the formed aggregates. We succeeded in synthesizing a clear sol containing polymeric aggregates with acceptable particle charge. The electrophoretic deposition on glassy carbon or C/C-SiC slabs led to homogenous layers. At low sol concentrations micro cracks in the deposited layers were observed whereas higher concentrations led to thin and dense layers. During constant current EPD a constant voltage was recorded indicating that the deposited layer does not lead to an increase in resistivity in this kind of EPD system.

Synthesis and Characterization of Vanadium Oxide Gels from Alkoxy-Vanadate Precursors

1988 ◽  
Vol 121 ◽  
Author(s):  
C. Sanchez ◽  
M. Nabavi ◽  
F. Taulelle
Keyword(s):  
Vanadium Oxide ◽  
Synthesis And Characterization ◽  
Large Excess ◽  
Vanadium Oxide Gels ◽  
Hydrolysis Conditions ◽  
Hydrolysis Of ◽  
Controlled Hydrolysis ◽  
Alkoxide Precursors ◽  
Inorganic Precursors

ABSTRACTVanadium oxide gels are synthesized through vanadium oxo-alkoxide hydrolysis condensation processes. Different precursors and hydrolysis conditions lead to different sorts of gels. V0(0Amt)3 hydrolyzed with a large excess of water results in red jammy gels with a layered structure. They exhibit electronic and ionic behavior comparable to vanadium pentoxide gels from inorganic precursors. Hydrolysis of VO(OPrn)3 in an alcoholic medium, leads to orange transparent monolithic gels. They have a highly branched polymeric structure. Controlled hydrolysis of vanadium oxo-alkoxide precursors has the further advantage of giving good adherent thin films.

scholarly journals Characterization of O-Acetylation of N-Acetylglucosamine

2011 ◽  
Vol 286 (27) ◽  
pp. 23950-23958 ◽  
Author(s):  
Elvis Bernard ◽  
Thomas Rolain ◽  
Pascal Courtin ◽  
Alain Guillot ◽  
Philippe Langella ◽  
...  
Keyword(s):  
Cell Wall ◽  
Structural Characterization ◽  
Bacterial Species ◽  
Muramic Acid ◽  
Gram Positive Bacteria ◽  
Mutant Strains ◽  
Encoding Genes ◽  
Hydrolysis Of ◽  
Cell Wall Hydrolysis

Peptidoglycan (PG) N-acetyl muramic acid (MurNAc) O-acetylation is widely spread in Gram-positive bacteria and is generally associated with resistance against lysozyme and endogenous autolysins. We report here the presence of O-acetylation on N-acetylglucosamine (GlcNAc) in Lactobacillus plantarum PG. This modification of glycan strands was never described in bacteria. Fine structural characterization of acetylated muropeptides released from L. plantarum PG demonstrated that both MurNAc and GlcNAc are O-acetylated in this species. These two PG post-modifications rely on two dedicated O-acetyltransferase encoding genes, named oatA and oatB, respectively. By analyzing the resistance to cell wall hydrolysis of mutant strains, we showed that GlcNAc O-acetylation inhibits N-acetylglucosaminidase Acm2, the major L. plantarum autolysin. In this bacterial species, inactivation of oatA, encoding MurNAc O-acetyltransferase, resulted in marked sensitivity to lysozyme. Moreover, MurNAc over-O-acetylation was shown to activate autolysis through the putative N-acetylmuramoyl-l-alanine amidase LytH enzyme. Our data indicate that in L. plantarum, two different O-acetyltransferases play original and antagonistic roles in the modulation of the activity of endogenous autolysins.

Hydrolysis of tri-tert-butylaluminum: the first structural characterization of alkylalumoxanes [(R2Al)2O]n and (RAlO)n

1993 ◽  
Vol 115 (12) ◽  
pp. 4971-4984 ◽  
Author(s):  
Mark R. Mason ◽  
Janna M. Smith ◽  
Simon G. Bott ◽  
Andrew R. Barron
Keyword(s):  
Structural Characterization ◽  
Hydrolysis Of
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