Search results for "Acetone"
showing 10 items of 350 documents
Secondary brown carbon formation via the dicarbonyl imine pathway: nitrogen heterocycle formation and synergistic effects.
2016
Dicarbonyls are known to be important precursors of so-called atmospheric brown carbon, significantly affecting aerosol optical properties and radiative forcing. In this systematic study we report the formation of light-absorbing nitrogen containing compounds from simple 1,2-, 1,3-, 1,4-, and 1,5-dicarbonyl + amine reactions. A combination of spectrophotometric and mass spectrometric techniques was used to characterize reaction products in solutions mimicking atmospheric particulates. Experiments with individual dicarbonyls and dicarbonyl mixtures in ammonium sulfate and glycine solutions demonstrate that nitrogen heterocycles are common structural motifs of brown carbon chromophores formed…
Influence of Silver Deposits on the Photocatalytic Activity of Titania
1997
The objectives of depositing metals over semiconductor photocatalysts are to improve the electron-hole pair separation and to increase the rate of the reduction process due to the catalytic properties of the metal itself. Most of the deposited (noble) metals that have been studied belonged to group VIII. Very few studies concerned silver deposits. In the present work, the influence of deposited silver over anatase or rutile has been followed in three different types of reactions: (i) metal deposition, (ii) oxidation, and (iii) dehydrogenation. The final solids obtained in the last reaction (Pt/Ag/TiO{sub 2}) were also used as catalysts in two other test reactions to make comparison with TiO…
Cr- and Sb-containing TiO 2 inorganic orange nano-pigments prepared by a relative long hydrocarbon chain polyol
2016
Abstract We report the preparation of a series of orange Cr- and Sb-containing TiO 2 nano-pigments by the polyol via using triethylenglycol (TEG). Poorly crystallized anatase nanopowders with nominal stoichiometric compositions Cr x Sb x Ti 1−2x O 2 , with 0 ≤ x ≤ 0.2, were obtained by heating at 180 °C a solution of antimony acetate, chromium acetylacetone and titanium butoxide in TEG. The transition temperature of the chromium- and antimonium-containing anatase nanoparticles into the rutile crystalline form occurred over the range of temperature between 500 and 650 °C, depending on the dopant amount. After annealing at 800 °C for short time the series of samples displaying the rutile stru…
Antimicrobial and antiproliferative activity of Peucedanum nebrodense (Guss.) Strohl.
2003
Abstract Acetone extract of Peucedanum nebrodense (Guss.) Strohl., a rare endemic species from the Madonie mountains (Sicily), was tested in vitro for its antimicrobial activity against bacterial reference strains and antiproliferative activity against K562 (human chronic myelogenous leukemia), HL-60 (human leukemia) and L1210 (murine leukemia) cell lines. The acetone extract showed antiproliferative IC 50 values in the range of 14–0.27 μg/ml.
Screening and authentication of herbal formulations based on microextraction-assisted voltammetry of microparticles
2015
A simple solid state electrochemical methodology for screening and authentication of herbal formulations is described. The proposed method is based on the recording of the voltammetric response, in contact with aqueous buffers, of microparticulate films of antioxidant compounds resulting from micro-extraction of dried herbal samples with ethanol or acetone. The obtained voltammetric responses led us to differentiate between diverse active components upon application of bivariate and multivariate chemometric techniques. Resolution of herbal preparations containing two or more components is possible when well-separated voltammetric signals are recorded. In favorable cases, such characteristic…
Physicochemical Interactions Between Aroma Compounds and Milk Proteins: Effect of Water and Protein Modification
1998
The physicochemical interactions between aroma compounds and sodium caseinate were studied by complementary techniques involving the protein in aqueous solution at 25 or 75 g/L (exponential dilution and equilibrium dialysis) or in a solid state (sorption and infrared spectroscopy). No retention of acetone, ethyl acetate, and 2-propanol in aqueous solutions was found by exponential dilution and equilibrium dialysis. Diacetyl and benzaldehyde interacted with sodium caseinate through strong and weak bonds, as found by equilibrium dialysis. The results obtained by sorption differ from those obtained in aqueous solutions. The compounds that sorbed best to sodium caseinate were acetone and ethyl …
Fractionation of unsubstituted cellulose from solutions in either Ni-tren or (N,N-dimethylacetamide + LiCl)
2000
Starting from solutions of unsubstituted cellulose (Avicel PH101, M w = 30.1 kg/mol and M w /M n = 3 or Solucell 500, M w = 230 kg/mol, M w /M n = 2.8) in either Nitren (0.8 M aqueous solution of the dihydroxotris(2-aminoethly)amine nickel(II) complex) or in a mixed solvent DMAc+LiCl (consisting of N,N-dimethylacetamide plus lithium chloride) it was investigated whether the segregation of a second phase caused by the addition of suitable precipitants leads to polymer fractionation. With Ni-tren the long chains accumulate in the precipitate formed upon the addition of sulfuric acid; as the pH falls below 9, the solution is free of cellulose. Nevertheless this route option for fractionation m…
Effects of the nature and concentration of substrates in aqueous solutions on the solubility of aroma compounds
2005
The solubility of nine aroma compounds (acetone, 2-butanone, 2-hexanone, 2-octanone, ethyl acetate, ethyl butanoate, ethyl hexanoate, n-hexanal, and n-hexanol) in both water and various aqueous solutions was measured at 25 °C using the mutual solubility method. The aqueous solutions consisted of sucrose, glucose, sorbitol, glycerol, polyethylene glycol 200, or maltodextrins at different concentrations. Aroma solubility in water decreased with increased hydrophobicity. For aroma molecules which have the same number of carbon atoms in their structure, aqueous solubility decreased as follows: aldehyde > methyl ketone > alcohol > ethyl ester. When using a group contribution method, the estimate…
New trials in the consolidation of waterlogged archaeological wood with different acetone-carried products
2011
Some acetone-carried consolidants for waterlogged archaeological wood were tested in order to evaluate treatments able to save time and energy. In details, colophony (rosin), two esterified colophonies (Rosin 100® and Rosin 459®), a mixture of colophony with PEG 3400 and a vinyl acetate - vinyl versate copolymer (Vinavil 8020S®) were tested. The treatments were carried out at temperatures of 20 and 35 °C on waterlogged maritime pine, elm, oak and beech. The materials came from the archaeological Site of the ancient ships of Pisa (Tuscany, Italy) and were dated back to VII cent. BC II cent. AD. To evaluate the processes, equilibrium moisture content and dimensional stability of treated woo…
Organosulfates in atmospheric aerosol: synthesis and quantitative analysis of pm<sub>2.5</sub> from xi'an, northwestern c…
2018
Abstract. The sources, formation mechanism and amount of organosulfates (OS) in atmospheric aerosol are not yet well understood, partly due to the lack of authentic standards for quantification. In this study, we report an improved robust procedure for the synthesis of organosulfates with different functional groups. Nine authentic organosulfate standards were synthesized and four standards (benzyl sulfate, phenyl sulfate, glycolic acid sulfate, and hydroxyacetone sulfate) were used to quantify their ambient concentrations. The authentic standards and ambient aerosol samples were analyzed using an optimized ultra performance liquid chromatography–electrospray ionization-tandem mass spectrom…