Home About us Contact
|
Home About us Contact | ||
|
|
||
Thioglycolic Acid (thioglycolic + acid)
Selected AbstractsSmall Molecule-Controlled Spontaneous Growth of Rose-Like Se Crystals at Room TemperatureEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2008Da-Wei Deng Abstract The spontaneous growth of rose-like Se crystals in aqueous solutions at room temperature is reported. The formation of rose-like Se crystals is based on the oxidation of Na2Se in the presence of thioglycerol solution at pH = 11 in a dark ambient atmosphere. In alkaline solutions, the growth evolution of rose-like Se crystals with aging time was followed by scanning electron microscopy (SEM), and an interesting formation process from initial Se monomers to amorphous Se (a-Se) spheres, and to the final rose-like complex structures of Se crystals was observed. Seven kinds of small molecules with different structures, including 1-thioglycerol (TG), mercaptamine (MA), L -cysteine (L -cys), 3-mercaptopropionic acid (MPA), thioglycolic acid (TGA), glycerol (GLY), and L -serine (L -ser), were used to manipulate the growth of Se crystals. The experimental results show that the structures of the small molecules play a key role in the growth of the Se crystals. The presence of thiols in the structure of the small molecules is favorable for the formation of the aggregates of Se crystals, and other termini, such as ,NH2, ,OH, or ,COO,, will determine whether the aggregates of Se crystals are made up of Se slices or Se prisms. These observations suggest that the ligand molecules have a crucial effect on the nucleation, monomers, and growth of nanocrystals. The selection of ligands can be extended to other important materials for further preparation of nanocrystals with desired shapes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Morphology- and Color-Tunable Bright Fibers with High Concentration of CdTe Nanocrystals Assembled through Sol,Gel ReactionADVANCED MATERIALS, Issue 40 2009Ping Yang Intensely luminescent fibers are prepared by the self-assembly of hybrid SiO2 -coated CdTe nanocrystals (NCs), SiO2 monomers, and a complex of Cd2+ and thioglycolic acid. These fibers exhibit tunable photoluminescent colors (yellow to red) and morphologies (tubal, solid, and belt-like) with an extremely high concentration of CdTe NCs by controlling the preparation parameters. [source] Phosphonic acid functionalized polyethylene glycol and derivativesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Mohamed Essahli Abstract This article describes the functionalization of polyethylene glycol, mono or bifunctional, and a nonionic surfactant by phosphonic acids without the need for protection of the functional group. The functionalization is performed in two steps, first an esterification by thioglycolic acid, secondly a radical addition of vinyl phosphonic acid on the thiol group. All products were obtained quantitatively and characterized by 1H-, 13C-, 31P-NMR spectroscopy techniques, MALDI, and step-by-step chemical titrations. Enhanced thermal properties were found while phosphonylating polyethylene glycol, particularly when the sulfur atom was oxidized into a sulfone group. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis of some novel methylene-bis-pyrimidinyl-spiro-4-thiazolidinones as biologically potent agentsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2008A. Srinivas A series of novel methylene-bis-pyrimidinyl-spiro-4-thiazolidinones 6a-h have been synthesized by cyclocondensation of thioglycolic acid with methylene-bis-(N -cyclohexylidene- N -pyrimidine) 5a-h, which in turn have been prepared by the reaction of cyclohexanone with methylene-bis-2-aminopyrimidines 4a-h, which are prepared by the reaction of guanidine hydrochloride with methylene-bis-chalcones 3a-h. The compounds 3a-h have been synthesized by the reaction of 5-(3-formyl-4-hydroxybenzyl)-2-hydroxybenzaldehyde 2 with various acetophenones in presence of KOH. The compound 2 is prepared by the reported method. The structures of the compounds synthesized have been confirmed by their elemental analysis and spectral data. Their antibacterial and antifungal activities have also been evaluated. [source] Synthesis of some thiazolyl and thiadiazolyl derivatives of substituted furan and pyrroleJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2007Seham Y. Hassan Four series of substituted furan and pyrrole have been synthesized. The first series was prepared by cyclization of the key intermediates ethyl 5-[(4-substituted thiosemicarbazido)methyl]-2-methylfuran-3-carboxylates 2a-2d and 1-[(4-acetyl-5-methyl-1H -pyrrol-2-yl)methylene]-4-substituted thiosemicarbazides 8a-8d with chloroacetic acid or (ethyl bromoacetate) to afford the corresponding 4-oxo-3-substituted thiazolidin-2-ylidene 3a-3d or 3-substituted thiazolidin-4-one 9a-9d. On the other hand, heating of the intermediates 2a-2d or 8a-8d with acetic anhydride afforded the corresponding (N -substituted acetylamino)-2,3-dihydro-[1,3,4]thiadiazol-2-yl derivatives 4a-4d and [1,3,4]thiadiazol-2-yl- N -substituted acetamide 10a-10d respectively, while cyclization with p -bromophenacyl bromide gave rise to the corresponding 3-substituted thiazol-2-yl-ylidene 5a-5d and 11a-11d respectively. Furthermore, 4-oxo-3-substituted thioureido-thiazolidin-2-yl 6a-6d or 4-oxo-thiazolidin-3-yl-3-substituted thiourea 12a-12d were obtained by reaction of the intermediates 2a-2d or 8a-8d with thioglycolic acid. Some of the synthesized compounds showed promising antimicrobial activities. [source] Detection of metallo-,-lactamases-encoding genes in environmental isolates of Aeromonas hydrophila and Aeromonas jandaeiLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2009L.C. Balsalobre Abstract Aims:, To determine the prevalence and expression of metallo-,-lactamases (MBL)-encoding genes in Aeromonas species recovered from natural water reservoirs in southeastern Brazil. Methods and Results:, Eighty - seven Aeromonas isolates belonging to Aeromonas hydrophila (n = 41) and Aer. jandaei (n = 46) species were tested for MBL production by the combined disk test using imipenem and meropenem disks as substrates and EDTA or thioglycolic acid as inhibitors. The presence of MBL genes was investigated by PCR and sequencing using new consensus primer pairs designed in this study. The cphA gene was found in 97·6% and 100% of Aer. hydrophila and Aer. jandaei isolates, respectively, whereas the acquired MBL genes blaIMP, blaVIM and blaSPM-1 were not detected. On the other hand, production of MBL activity was detectable in 87·8% and 10·9% of the cphA -positive Aer. hydrophila and Aer. jandaei isolates respectively. Conclusions:, Our results indicate that cphA seems to be intrinsic in the environmental isolates of Aer. hydrophila and Aer. jandaei in southeastern Brazil, although, based on the combined disk test, not all of them are apparently able to express the enzymatic activity. Significance and Impact of the Study:, These data confirm the presence of MBL-producing Aeromonas species in natural water reservoirs. Risk of waterborne diseases owing to domestic and industrial uses of freshwater should be re-examined from the increase of bacterial resistance point of view. [source] Preparation of highly H+ permeable sulfonated poly(ether ether ketone) cation exchange membranes and their applications in electro-generation of thioglycolic acidPOLYMER INTERNATIONAL, Issue 7 2009Xuehong Huang Abstract BACKGROUND: Sulfonated poly(ether ether ketone) (SPEEK) was successfully synthesized from sulfonated 4,4,-difluorobenzophenone, 4,4,-difluorobenzophenone and bisphenol A. SPEEK cation exchange membranes were prepared by the casting method. The composition and morphology of SPEEK were characterized using Fourier transform infrared and 1H NMR spectroscopies, respectively. The ion exchange capacity (IEC), water uptake and degree of swelling of the membranes were also investigated. SPEEK120 was used as a separator in an electrolysis cell to produce thioglycolic acid (TGA). RESULTS: SPEEK polymerization was carried out at 145 and 175 °C for 10 h. The IEC of the SPEEK membranes was measured as 0.24,2.02 meq g,1 and the water uptake as 2.26,26.45%. The degree of swelling of the membranes was 1.71,15.28%. TGA was effectively prepared by electro-reduction of dithioglycolic acid. The current efficiency peaked at 58.31% at room temperature with a current density of 15 mA cm,2. CONCLUSION: SPEEK120 membrane shows good dimensional stability and H+ permeability. Compared to the traditional metal-reduction method, the current electro-reduction technique avoids the use of zinc powder and so reduces environmental pollution. Copyright © 2009 Society of Chemical Industry [source] Soil bacterium Pseudomonas sp.: destroyer of mustard gas hydrolysis productsBIOTECHNOLOGY JOURNAL, Issue 8 2007Nadezda Medvedeva Professor Abstract A bacterial culture capable of utilizing products of mustard gas hydrolysis as a source of carbon was isolated from soil. This culture was tolerant to organochlorine substances in the hydrolysate. The bacterium was identified as Pseudomonas sp. The bacterium utilizes the major product of mustard gas hydrolysis, thiodiglycol, through two pathways. One involves the oxidation of the primary alcoholic groups in thiodiglycol, yielding thiodiglycolic and thioglycolic acids. The cleavage of the C-S bonds in these acids gives rise to acetate, which is then used further in the cell metabolism. The other pathway involves the cleavage of the C-S bond in the thiodiglycol molecule, yielding ,-mercaptoethanol, which is transformed by Pseudomonas sp. into thioglycolic acid. The results show the promise of this bacterium for the bioremediation of mustard gas-contaminated soils. [source] Size-Tunable Highly Luminescent SiO2 Particles Impregnated with Number-Adjusted CdTe NanocrystalsCHEMPHYSCHEM, Issue 4 2010Ping Yang Dr. Abstract Highly luminescent SiO2 particles impregnated with CdTe nanocrystals (NCs) are prepared by a sol,gel procedure. Partial ligand exchange from thioglycolic acid to 3-mercaptopropyltrimethoxysilane (MPS) on the NCs enables retention of the initial photoluminescence (PL) efficiency of the NCs in water, while the simultaneous addition of a poor solvent (ethanol) results in regulated assembly of the NCs through condensation of hydrolyzed MPS. The SiO2 particles thus prepared have, for example, a diameter of 16 nm and contain three NCs each. The PL efficiency of these particles is 40,%, while the initial efficiency is 46,% in a colloidal solution. The redshift and narrowed spectral width in PL observed after impregnation indicate that the concentration of NCs in these nearly reaches the ultimate value (on the order of 1021 particles per liter). The porosity of these particles is investigated by means of N2 adsorption,desorption isotherms. Due to the SiO2 shell, these particles have higher stability in phosphate-buffered saline buffer solution than the initial NCs. Their potential use for labeling in bio-applications is investigated by conjugating biotinylated immunoglobulin G to them by using streptavidin maleimide as linker. Successful conjugation is confirmed by electrophoresis in agarose gel. This preparation method is an important step towards fabricating intensely emitting biocompatible SiO2 particles impregnated with semiconductor NCs. [source] Soil bacterium Pseudomonas sp.: destroyer of mustard gas hydrolysis productsBIOTECHNOLOGY JOURNAL, Issue 8 2007Nadezda Medvedeva Professor Abstract A bacterial culture capable of utilizing products of mustard gas hydrolysis as a source of carbon was isolated from soil. This culture was tolerant to organochlorine substances in the hydrolysate. The bacterium was identified as Pseudomonas sp. The bacterium utilizes the major product of mustard gas hydrolysis, thiodiglycol, through two pathways. One involves the oxidation of the primary alcoholic groups in thiodiglycol, yielding thiodiglycolic and thioglycolic acids. The cleavage of the C-S bonds in these acids gives rise to acetate, which is then used further in the cell metabolism. The other pathway involves the cleavage of the C-S bond in the thiodiglycol molecule, yielding ,-mercaptoethanol, which is transformed by Pseudomonas sp. into thioglycolic acid. The results show the promise of this bacterium for the bioremediation of mustard gas-contaminated soils. [source] | ||||||||||||||||