1,720,995 research outputs found
Il degrado in edilizia (cap.1 pp 1-10); Analisi fenomenologica del degrado (cap.2 pp. 11-14)
No full textRivestimento in laterizio faccia a vista (cap.5 pp.49-66), Rivestimento il laterizio appeso (cap.6 pp.67-76)
No full textRivestimento continuo (cap.3 pp.15-36), Rivestimento continuo con coibente esterno (cap.4 pp.37-48)
No full textPulsed Positive/Negative Chemical Ionization Mass Spectrometry of Pyrazines
No full textThe mass spectrometric behavior of thirteen pyrazines under PPINICI conditions was investigated using methane as reagent gas. Differences in the mass spectra were observed depending on analyte concentration. Structural informations can be obtained, but data are highly influenced by experimental conditions
Homolytic reductive alkylation of methylvinyl ketone with ethers by Ti(III) decomposition of t-butyl hydroperoxide
No full textReductive alkylatin of methylvinylketone has been accomplished by hydrogen abstraction from cyclic ethers with the redox couple: t-butyl hydroperoxide-titanous chloride. A redox radical mechanism is proposed and the selectivity of the hydrogen abstraction by t-butoxy radicals and reduction of α-ketoalkyl radical by titanous ions is discussed
Strecker degradation of leucine and valine in a lipidic model system
No full textLeucine and valine were reacted with fructose in a mixture of cocoa butter and water at different temperatures. The rate of the Strecker reaction is higher in cocoa butter-water than in water. In the presence of cocoa butter the two amino acids give some aldehyde also without sugar. The participation of cocoa butter in the production of flavor during the roasting of cocoa beans is therefore proposed
Flavor components in the Maillard reaction of different amino acids with fructose in cocoa butter-water. Qualitative and quantitative analysis of pyrazines
No full textEight amino acids were reacted with fructose in deodorized cocoa butter-water as a model of the Maillard reaction in cocoa beans. Detailed GC/MS analysis of the volatile compounds obtained is reported with particular reference to similarities and differences in the patterns obtained with the amino acids. A quantitative analysis of pyrazines is described. Among the 22 pyrazines detected, 15 had been already reported in roasted cocoa beans. 2-(3-Methylbutyl)-3,6-dimethylpyrazine was formed in the reaction of leucine, while lysine gave three 2-methoxy-3-alkylpyrazines not reported in cocoa
EVALUATION OF AN AUTOMATIC GAS-CHROMATOGRAPHIC SYSTEM FOR THE IDENTIFICATION OF BACTERIAL INFECTIVE AGENTS
No full textThe potential clinical application of gas chromatography to
microbial identifcation was evaluated. A completely automated
system, the MIS (Microbial Identification System; Hewlett-
Packard) can analyse and identify pure strains by comparison of
their cellular fatty acids patterns (C9-C2o) with the reference
parameters stored in a library. Three hundred and sixty-seven
strains were tested, comparing the gas chromatographic results
with those obtained by the traditional microbiological methods in
the bacteriology laboratory of our Institute. A standardized
extractive procedure was followed to obtain the fatty acid methyl
esters (FAMEs), but some modifications to the recommended
procedure were introduced in the bacterial growth procedures:
colonies harvested not onlyfrom the recommended growth media but
also from selective media routinely used in the bacteriology
laboratory were successfully examined. These modifications did not
influence the results but improved the ease for the user; good
agreement with the comparison method was observed as far as
identications ofgenus and species are concernedfor 238 cases.
The major advantages of this computerized system are a reduction
in the time required to obtain thejnal results, the elimination of
human errors by using the autosampler and a better inter-laboratory
comparability ofresults owing to a higher degree ofobjectivity. On
the other hand, the limited throughput ofMIS (only 40 samples in
24 h) prevents its use in a large routine laboratory; this technology
is appropriate in emergency cases, in taxonomic studies and as a
confirmatory method
Formation in aqueous solution of N-nitroso curzate and the catalytic effect of some anions
No full text
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