Results 1 - 10 of 9493
Results 1 - 10 of 9493. Search took: 0.036 seconds
|Sort by: date | relevance|
[en] 1. Gamma-initiated Polymerization of Vinyl Acetate in an Aqueous Solution of Uranyl Acetate. From a consideration of the rate and degree of polymerization of the gamma- initiated polymerization of vinyl-acetate in three systems (vinyl acetate-acetic acid, vinyl acetate-acetic acid, water, and vinyl acetate-acetic acid-water-uranyl acetate), the G-values of each component for the initiation of polymerization are estimated as follows G vinylacetateinitiation = 10,6; G aceticacidinitiation = 52; G waterinitiation = 480; G uranylacetateinitiation = 23,000. 2. Gamma-initiated Polymerization of Vinyl Acetate in Aqueous Solutions of Detergents. The emulsion polymerization of vinyl acetate in the presence of anionic, cationic and non ionic detergents is discussed. The rate is found to be greatest for the anionic detergent lauryl benzene sulphonate. The rate and degree of polymerization increase with detergent concentration. It is found that the rate of polymerization is ∝ (Intensity)0.25.
[fr]1. Polymerisation, provoquee par les rayons gamma, de l'acetate de vinyle en solution aqueuse d'acetate d'uranyle. En se fondant sur le rythme et le degre de la polymerisation de l'acetate de vinyle, provoquee par les rayons gamma, dans trois groupes differents (acetate de vinyle-acide acetique; acetate de vinyle-acide acetique-eau; acetate de vinyle-acide acetique-eau-acetate d'uranyle), on a estime comme suit les valeurs G correspondant a chaque element constitutif pour l'amorcage de la polymerisation provoquee par les rayons gamma: G acetatedevinyleamorcage = 10,6; G acideacetiqueamorcage = 52; G eauamorcage = 480; G acetated'uranyleamorcage = 23 000. 2. Polymerisation de l'acetate de vinyle, provoquee par les rayons gamma, dans des solutions aqueuses de detergents. Les auteurs examinent la polymerisation de l'emulsion d'acetate de vinyle en presence de detergents anioniques, cathioniques et non-ioniques. Ils constatent que le rythme est plus rapide pour le detergent anionique lauryle-benzene-sulfonate. Le rythme et le degre de polymerisation augmentent avec la concentration du detergent. On constate que le rythme de polymerisation est proportionnel a I0,25 (I = intensite). (author)
[es]1. Polimerizacion del acetato de vinilo en solucion acuosa de acetato de uranilo iniciada por los rayos gamma. Utilizando los resultados de un estudio de la velocidad y del grado de polimerizacion del acetato de vinilo iniciada por los rayos gamma, realizado con tres sistemas distintos (acetato de vinilo-acido acetico, acetato de vinilo-acido acetico-agua, y acetato de vinilo-acido acetico-agua-acetato de uranilo), los autores han calculado los siguientes valores de G correspondientes a cada componente para la polimerizacion iniciada mediante rayos gamma: G acetatodeviniloiniciacion = 10.6; G acidoaceticoiniciacion = 52; G aguainiciacion = 480; G acetatodeuraniloiniciacion = 23 000. 2. Polimerizacion del acetato de vinilo en soluciones acuosas de detergentes iniciada por los rayos gamma Los autores estudiaron la polimerizacion en emulsion del acetato de vinilo en presencia de detergentes anionicos, cationicos y no ionicos. Han comprobado que la velocidad de polimerizacion es maxima cuando se utiliza bencenosulfonato de laurilo como detergente anionico. La velocidad y el grado de polimerizacion aumentan con la concentracion del detergente. Los estudios revelaron ademas que la velocidad de polimerizacion es porporcional a la raiz cuarta de la intensidad de irradiacion. (author)
[ru]I. Polimerizatsiya vinil-atsetata v vodnykh rastvorakh atsetata uranila pod vliyaniem gamma-izluchenij . Na osnovanii izucheniya skorosti i stepeni polimerizatsi i vinil- atsetata pod vliyaniem gamma-izluchenij v trekh kombinatsiyakh (vinil- atsetat - atsetatnaya kislota; vinil-atsetat - vodnyj rastvor atsetatnoj kisloty ; vinil-atsetat - atsetatnaya kislota - voda - uksusno-kislyj uranil), znachenie ,,G'' kazhdoj iz sostavnykh chastej ehtikh kombinatsij pri vozbuzhdenii polimerizatsii otsenivaetsya sleduyushchim poryadkom: G vinil-atsetatavozbuzhdenie = 10,6; G atsetatnojkislotyvozbuzhdenie = 52; G vodyvozbuzhdenie = 480; G uksusnokislogouranilavozbuzhdenie = 23 000. 2. Vozbuzhdaemaya gamma-izlucheniyami polimerizatsiya vinil-atsetata v vodnykh rastvorakh moyushchikh veshchestv. V doklade obsuzhdaetsya polimerizatsiya ehmul'sii vinil-atsetata pri nalichii anionnykh, kationnykh i ne-ionnykh moyushchikh veshchestv. Ustanovleno, chto naibol'shaya skorost' dejstviya prinadlezhit anionnomu moyushchemu veshchestvu-sul'fatu laurinovogo benzola. Bystrota i stepen' polimerizatsii vozrastayut po mere nasyshchennosti rastvora. Ustanovleno, chto skorost' polimerizatsii ravna ∝ (1 intensivnost') 0,25. (author)
[en] ACH1 encodes a mitochondrial enzyme of Saccharomyces cerevisiae endowed with CoA-transferase activity. It catalyzes the CoASH transfer from succinyl-CoA to acetate generating acetyl-CoA. It is known that ACH1 inactivation results in growth defects on media containing acetate as a sole carbon and energy source which are particularly severe at low pH. Here, we show that chronological aging ach1Δ cells which accumulate a high amount of extracellular acetic acid display a reduced chronological lifespan. The faster drop of cell survival is completely abrogated by alleviating the acid stress either by a calorie restricted regimen that prevents acetic acid production or by transferring chronologically aging mutant cells to water. Moreover, the short-lived phenotype of ach1Δ cells is accompanied by reactive oxygen species accumulation, severe mitochondrial damage, and an early insurgence of apoptosis. A similar pattern of endogenous severe oxidative stress is observed when ach1Δ cells are cultured using acetic acid as a carbon source under acidic conditions. On the whole, our data provide further evidence of the role of acetic acid as cell-extrinsic mediator of cell death during chronological aging and highlight a primary role of Ach1 enzymatic activity in acetic acid detoxification which is important for mitochondrial functionality.
[en] Highlights: • VLE data for methanol + 2-butyl alcohol were determined. • VLE data for methyl acetate + methanol + 2-butyl alcohol + SBAC were determined. • The binary interaction parameters were obtained based on the binary VLE data. • The data of quaternary system have been predicted. • Both Wilson and NRTL models are suitable to describe the VLE of quaternary system. - Abstract: In this paper, isobaric (vapor + liquid) equilibrium (VLE) data for the binary system methanol + 2-butyl alcohol and the quaternary system methyl acetate + methanol + 2-butyl alcohol + 2-butyl acetate were determined at P = 101.33 kPa in a modified Rose still. The binary VLE data were found to be thermodynamic consistency by the Herrington method. The VLE data for the binary system were correlated by the Wilson and NRTL equations respectively, which were used to predict the VLE data of the quaternary system. The results showed that the Wilson and NRTL models matched well with the (vapor + liquid) phase equilibrium data. The deviations for the vapor-phase compositions and the equilibrium temperatures are reasonably small and the models are both suitable for these systems
[en] Densities and viscosities of the binary mixtures of 2,4,6-trimethyl-1,3,5-trioxane with methyl acetate, ethyl acetate, and 1-butyl acetate were measured over the entire mole fractions at (298.15, 303.15, and 308.15) K. Using the experimental values of densities ρ and viscosities η, excess molar volumes V E, viscosity deviations δη were calculated. The values of excess molar volumes V E and viscosity deviations δη were fitted to the Redlich-Kister polynomial
[en] Recently, the electrospinning technique has been explored as a natural and synthetic polymer processing tool due to its versatility and potential to generate complex structures at a nanoscale. In this work, non-woven nanofibrous mats were electrospun, with a structure resembling the extracellular matrix, for prospective biomedical uses. Poly (vinyl alcohol) (PVA) and cellulose acetate (CA) based electrospun nanofibrous meshes were prepared at different ratios 100/0, 90/10, 80/20 and 70/30 and characterized in terms of fiber diameter. The process was kept as green as possible by resorting to a combination of acetic acid and distilled water as solvents. Optimal conditions for PVA/CA processing were established at 29 kV, feeding rate of 0.8 mL/h and distance between needle and collector of 17 cm. These allowed for the most uniform fibers with the smallest diameters to be produced. (paper)
[en] An efficient and simple protocol for the synthesis of a new class of diversely functionalized novel indole and coumarin containing pyridine-3-carbonitrile derivatives has been described through one-pot four-component condensation reaction of 3-(1H-indol-3-yl)-3-oxopropanenitrile, various aldehydes, 3-acetyl-2H-chromenones, and ammonium acetate in acetic acid conditions. The present new methodology offers several advantages such as short reaction time, easy experimental work-up, and good product yield, and endures the substrate diversity and operational simplicity under metal-free reaction conditions for the formation of C–C/C–N bonds. Graphical abstract: .
[en] The furan-2-ylidene acetates (3a-d), obtained from the furan-2,3-diones (1a-b) and methyl/ethyl (triphenyl phosphoranylidene)- acetates (2a-b), were converted via the Michael type reactions with 2,3-diaminopyridine and its derivatives (4a-c) into the corresponding pyrrol-2-ylidene-acetates (5a-j) in moderate yields (45-94%). Structures of these compounds were determined by the IR, NMR, elemental analysis, and X-ray diffraction method
[en] A few sorts of spirit were irradiated with a dose of 1 or 5 Mrad of 60Co gamma-rays. Then the chemical composition of spirits was investigated. It was found that as a result of irradiation the content of acids, esters, acetal aldehydes and methanol increases, while the strength of higher alcohols decreases slightly. The changes of compounds content in particular spirits are dependent on radiation doses and chemical composition before irradiation. It was also discovered that spirit irradiation causes decrease or even disappearance of characteristic - for given spirits - maxima of UV absorption. (Z.M.)
[en] The corrosion behavior of carbon steel (N80) in carbon dioxide saturated 1%NaCl solution with and without acetic acid or acetate was investigated by weight-loss test, electrochemical methods (polarization curve, Electrochemical impedance spectroscopy). The major objective is to make clear that the effect of acetic acid and acetate on the corrosion of carbon steel in CO2 environments. The results indicate that either acetic acid or acetate accelerates cathodic reducing reaction, facilitates dissolution of corrosion products on carbon steel, and so promotes the corrosion rate of carbon steel in carbon dioxide saturated NaCl solution. All Nyquist Plots are consisting of a capacitive loop in high frequency region, an inductive loop in medial frequency region and a capacitive arc in low frequency region. The high frequency capacitive loop, medial frequency inductive loop and low frequency capacitive arc are corresponding to the electron transfer reaction, the formation/adsorption of intermediates and dissolution of corrosion products respectively. All arc of the measured impedance reduced with the increase of the concentration of Ac-, especially HAc. However, the same phenomenon is not notable after reducing pH value by adding HCI. HAc is a stronger proton donor and can be reduced directly by electrochemical reaction firstly. Ac- can't participate in electrochemistry reaction directly, but Ac- an hydrate easily to create HAc in carbon dioxide saturated environments. HAc is as catalyst in CO2 corrosion. As a result, the corrosion rate was accelerated in the presence of acetate ion even pH value of solution increased
[en] Two methods for the synthesis of new axially chiral bipyridine N,N′-dioxides based on catalytic [2+2+2] cyclotrimerization of diynes with nitriles were developed. The N,N′-dioxides were used as catalysts in enantioselective allylation of benzaldehyde with allyltrichlorosilane and aldol reaction of trichlorosilyl ketene acetal of methyl acetate with acetophenone. Graphical abstract: .