- Coupled heterogeneous photocatalysis using a P-TiO2-αFe2O3 catalyst and K2S2O8 for the efficient degradation of a sulfonamide mixture
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Phosphorous-doped Ti-Fe mixed oxide (P-TiO2-αFe2O3) catalysts were prepared by the microwave-assisted sol-gel route and characterized using XRD, SEM, N2 physisorption, UV–vis diffuse reflectance, FTIR, and XPS. P-TiO2-αFe2O3 was evaluated during the degradation of a sulfonamide mixture (5 mg/L, each) under visible light. The photocatalytic process was optimized with a face-centered central composite design. Under optimal conditions (0.5 wt% of αFe2O3, pH 10, and 0.75 g/L of catalyst loading), the sulfate radical advanced oxidation process was carried out using 5 mM K2S2O8 (PS). P doping shifted the light absorption of P-TiO2-αFe2O3 in the visible light range owing to substitutional doping, while the coupling of P-TiO2 with α-Fe2O3 enhanced the absorption in the visible range, which resulted in an increase in the lifetime of the charge carriers and in a superior photoactivity of the P-TiO2-αFe2O3 catalyst in comparison to that of TiO2. The mineralization yield of the sulfonamides (SNs) mixture was enhanced in the presence of an electron acceptor (SO4 ? [rad]), allowing nearly 69 % within 300 min with the P-TiO2-αFe2O3/PS system, while P-TiO2-αFe2O3 and K2S2O8 oxidation achieved only 27 % and 21 %, respectively. The biodegradability index was 0.48 using the P-TiO2-αFe2O3/PS system, indicating a less toxic effluent than the original compounds. Recycling tests demonstrated that P-TiO2-αFe2O3 exhibits good stability in activating PS for SNs degradation during three cycles. Two main intermediates (pyrimidine and hydroquinone) and their hydroxylated re-arrangements were detected during the degradation of the SNs by the coupled process. Oxalic, oxamic, sulfonic, and acetic acids were also identified as by-products from the degradation of the SNs.
- Guzmán-Mar, Jorge L.,Hernández-Ramírez, Aracely,Hinojosa-Reyes, Laura,Mendiola-Alvarez, Sandra Y.,Palomino-Cabello, Carlos,Turnes-Palomino, Gemma
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- Electrochemical oxidation of amoxicillin on carbon nanotubes and carbon nanotube supported metal modified electrodes
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The electrolysis of amoxicillin (AMX) was carried out on CNT, Pt/CNT and Ru/CNT modified electrodes based on Carbon Toray in 0.1 M NaOH, 0.1 M NaCl and 0.1 M Na2CO3/NaHCO3 buffer (pH 10) media with the aim of studying the significance of two factors, electrode material and pH, on the oxidative degradation and mineralization of AMX. For this purpose, the electrolysis products were identified by HPLC-MS and GC–MS, and quantified by HPLC-UV-RID and IC. The highest carbon mineralization efficiency, corresponding to 30% of the oxidized AMX, was found for Pt/CNT modified electrode in carbonate buffer medium. Regarding to the AMX conversion, the results show that the effect of pH is higher than that of the electrode material. Principal component analysis allowed to determine the experimental parameters vs. product distribution relationship and to elucidate the oxidation pathways for the studied electrodes. The results show that the hydroxylation of the aromatic ring and the nitrogen atom play an important role on the efficient degradation of AMX.
- Ferreira, Marta,Kuzniarska-Biernacka, Iwona,Fonseca, António M.,Neves, Isabel C.,Soares, Olívia S.G.P.,Pereira, Manuel F.R.,Figueiredo, José L.,Parpot, Pier
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p. 322 - 331
(2019/07/10)
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- Metal-, Photocatalyst-, and Light-Free Direct C-H Acylation and Carbamoylation of Heterocycles
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Direct C-H acylations and carbamoylations of heterocycles can now be readily achieved without requiring any conventional metal, photocatalyst, electrocatalysis, or light activation, thus significantly improving on sustainability, costs, toxicity, waste, and simplicity of the operational procedure. These mild conditions are also suitable for gram-scale reactions and late-stage functionalizations of complex molecules, including pharmaceuticals, N,N-ligands, and light-sensitive molecules.
- Westwood, Matthew T.,Lamb, Claire J. C.,Sutherland, Daniel R.,Lee, Ai-Lan
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supporting information
p. 7119 - 7123
(2019/09/03)
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- Application of anodic oxidation, electro-Fenton and UVA photoelectro-Fenton to decolorize and mineralize acidic solutions of Reactive Yellow 160 azo dye
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The degradation of 100 cm3 of a solution with 0.167 mmol dm-3 Reactive Yellow 160 (RY160) azo dye in sulfate medium at pH 3.0 has been comparatively studied by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF). Trials were carried out with a stirred tank reactor equipped with a boron-doped diamond (BDD) anode and an air-diffusion cathode for H2O2 production, upon addition of 0.50 mmol dm-3 Fe2+ as catalyst in EF and PEF. The solution was slowly decolorized by AO-H2O2 because of the low rate of reaction of the azo dye and its colored products with hydroxyl radicals generated at the BDD anode from water oxidation. The color loss was enhanced in EF by the larger oxidation ability of hydroxyl radicals produced in the bulk from Fenton's reaction between added Fe2+ and generated H2O2, whereas the solution was more rapidly decolorized by PEF owing to the additional generation of hydroxyl radicals from the photolysis of Fe(III)-hydroxy complexes by UVA light. The relative mineralization ability of the processes also increased in the sequence AO-H2O2 -2. The influence of current density and RY160 concentration on the performance of all processes was assessed. Final carboxylic acids like maleic, fumaric, tartronic, acetic, oxalic, oxamic and formic were quantified by ion-exclusion HPLC. All these acids were totally removed by PEF, but the formation of small amounts of other highly recalcitrant products impeded the total mineralization. Chloride, sulfate, ammonium and, to a smaller extent, nitrate ions were released to the solution from the heteroatoms of the azo dye in all cases.
- Bedolla-Guzman, Alejandro,Sirés, Ignasi,Thiam, Abdoulaye,Peralta-Hernández, Juan Manuel,Gutiérrez-Granados, Silvia,Brillas, Enric
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p. 307 - 316
(2016/05/11)
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- Degradation of a veterinary pharmaceutical product in water by electro-oxidation using a BDD anode
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The electrochemical oxidation (EO) treatment in water of Fantetra, a veterinary drug widely used in Chile, and its components: oxytetracycline hydrochloride, phtalylsulfathiazole and diphenhydramine, has been carried out at constant current using a BDD/Stainless steel system. First, solutions of each drug were electrolyzed following the decay of the absorbance of each compound and total organic carbon abatement. The mineralization of the Fantetra commercial formulation was also studied. An analysis of the degradation by-products was made by high performance liquid chromatography. Thus, during the degradation of each pharmaceutical by the electrochemical oxidation process, aliphatic carboxylic acids were detected prior to their complete mineralization to CO2 and nitrogen ions, while NO3- and NH4+ remain in the treated solution. This is an essential preliminary step towards the applicability of the EO processes for the treatment of wastewater containing pharmaceutical compounds.
- Espinoza, C.,Contreras, N.,Berros, C.,Salazar, R.
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p. 2507 - 2511
(2015/02/05)
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- STEM-LIKE CELLS AND METHOD FOR REPROGRAMMING ADULT MAMMALIAN SOMATIC CELLS
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A new use is provided for small molecule inhibitors of Oct4 and Sox 2 as a cellular reprogramming agent and a method of reprogramming adult mammalian somatic cells into stem-like cells is provided, using small molecule inhibitors of Oct4 and Sox 2 without the need of any material derived from embryos or fetuses, and without the need of potentially harmful transfecting vectors. Stem-like cells created by the present invention can be induced to differentiate into terminally differentiated adult somatic cells, such as, for example, neuronal cells.
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- Oxidation of aminodinitrotoluenes with ozone: Products and pathways
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An investigation of the products from the reaction of ozone with aminodinitrotoluenes (ADNTs) provides information about the oxidation pathway. Studies conducted at low conversions of 2- and 4-ADNT show 2:1 ozone/ADNT stoichiometries, prompt formation of glyoxylic and pyruvic acids, and NO2- and NO3- (NOx) ions. Reaction schemes to account for these results involve a 1,3-dipolar cycloaddition of ozone to selected double bonds of the aromatic ring, leading to ring cleavage. 15N-Labeling experiments indicate that the amino function is not involved in the initial ozone oxidation and eventually is incorporated into pyruvamide (2-ADNT) and oxamic acid (4-ADNT) before being oxidized to nitrate.
- Spanggord, Ronald J.,Yao, C. David,Mill, Theodore
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p. 497 - 504
(2007/10/03)
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- Ozone and hydroxyl radicals induced oxidation of glycine
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The study of the oxidation of glycine by ozone and hydroxyl radicals has been undertaken. Different experimental procedures involving the H2O2/UV process or ozone in the presence of hydrogen peroxide on one hand, and ozone alone on the other hand allowed to distinguish between the two oxidation pathways. It has been shown that nitrites and nitrates are observed byproducts resulting from molecular ozonation whereas ammonium ions constitute the only inorganic nitrogen species from hydroxyl radicals induced decomposition of glycine. Therefore, the ozonation process promoting radical pathways will favor ammonia production vs. nitrates. Among the organic compounds resulting from oxidation by hydroxyl radicals, oxalic acid was the major byproduct detected in the presence of oxygen. Oxamic acid and formic acid were also observed. In addition, the nitrogen mass balance indicated the formation of unidentified nitrogen byproducts derived from glycine. These nitrogen compounds could result from the interaction of oxygen with nitrogen radical, but, mainly, with α-amino radical of glycine. This reaction is very different from the molecular ozonation which directs the attack on the nitrogen functional group before the C-N bond cleavage of the amino acid molecule. The study of the oxidation of glycine by ozone and hydroxyl radicals has been undertaken. Different experimental procedures involving the H2O2/UV process or ozone in the presence of hydrogen peroxide on one hand, and ozone alone on the other hand allowed to distinguish between the two oxidation pathways. It has been shown that nitrites and nitrates are observed byproducts resulting from molecular ozonation whereas ammonium ions constitute the only inorganic nitrogen species from hydroxyl radicals induced decomposition of glycine. Therefore, the ozonation process promoting radical pathways will favor ammonia production vs. nitrates. Among the organic compounds resulting from oxidation by hydroxyl radicals, oxalic acid was the major byproduct detected in the presence of oxygen. Oxamic acid and formic acid were also observed. In addition, the nitrogen mass balance indicated the formation of unidentified nitrogen byproducts derived from glycine. These nitrogen compounds could result from the interaction of oxygen with nitrogen radical, but, mainly, with α-amino radical of glycine. This reaction is very different from the molecular ozonation which directs the attack on the nitrogen functional group before the C-N bond cleavage of the amino acid molecule.
- Berger,Karpel Vel Leitner,Dore,Legube
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p. 433 - 441
(2007/10/03)
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- Compound containing an oxamic acid group, a process for producing the compound, and a resin composition containing the compound
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The present invention relates to compounds containing an oxamic acid group, which show high reactivity and have stability for water and are used as paints, adhesives, and plastic materials etc. in the form of a reaction material or a resin. Since into these compounds an oxamic acid group is introduced in a part of the molecule and the oxamic acid group is an ionic functional group, the compounds show superior solubility and dispersing character in water and also, since the oxamic acid group is a group of a disappearing type with heating, the compounds do not remain, after hardening, in the hardened product. Accordingly, the hardened products obtained from these compounds are superior in water-resistant and anticorrosion properties and in durability.
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- Reactivities of Oxalamidines (N,N-Oxalins)
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In order to determine the reactivity characteristics of putative oxalamidine metabolites (monoamidines of oxalic acid or N,N-oxalins), a series of cyclic and acyclic derivatives were synthesized and their reactivities examined.The results indicate that around neutral pH at 37 deg C oxalamidines are stable to hydrolysis or attack by nucleophiles typical of those that would be encountered physiologically.Also, under such conditions metal ions do not appreciably catalyze their destruction.The results further indicate that oxalamidines are stable to acid conditions (at least to 1 M HCl) but that they are readily hydrolyzed under basic conditions to oxamate derivatives.Kinetic and product data for the base-catalyzed reaction can be analyzed in terms of a mechanism similar to that proposed earlier for the hydrolysis of other amidines.This involves reversible addition of hydroxide to the protonated amidine followed by rate determining loss of amine.
- Chae, Myeong Yun,Hamilton, Gordon A.
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p. 217 - 226
(2007/10/03)
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- Intramolecular Influence of a Carboxylic Function on Platinium Blue Synthesis. A systematic Study of Complexes Originating from Acid Amides
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The use of acid amide as ligand for obtaining platinium blue has been investigated.While blue compounds are generally obtained by using the hydrolysis product of cis-dichlorodiammineplatinum(II) as platinum surce, with such ligands the reaction occurs very readily using potassium tetrachloroplatinate(II).The role of the carboxylic function which offers here a primary ligating site to platinum is evidenced.The compounds obtained have been characterized by UV-visible spectral measurments, Ce(IV) oxydative titration , ESR spectroscopy, and magnetic properties.Antitumoral activity toward leukemia L1210 and sarcoma 180 is reported for two of thesecompounds.As a first step for this antitumor study, these compounds have been found to be inactive toward Leukemia while they presnt intersting activity toward Sarcoma.
- Arrizabalaga, Philippe,Castan, Paule,Laurent, Jean-Pierre
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p. 4814 - 4818
(2007/10/02)
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- Organic compounds substituted heptadeca-5,9- and 5,10-dienoic acid
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The present invention provides novel substituted heptadeca-5,9- and 5,10-dienoic acid and similar fatty acid compounds which are derivatives of certain prostaglandins and are potent thromboxane A2 inhibitors. By virtue of this pharmacological property, they represent useful pharmacological agents for a wide variety of purposes.
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