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Clostridium perfringens is a widely distributed foodborne pathogen. Its ability to survive cold encounters could contribute to its persistence in foods and the potential to cause disease. In this work five cold-shock proteins (101, 82, 70, 45 and 10 kDa) were induced by cold-shocking C. perfringens FD-1041 from 43 °C to 28 °C, as revealed by labeling with L-[35S]methionine and cysteine followed by gel electrophoresis. Cold shock also increased the cold tolerance of the cells at least fifteen fold. The acquired tolerance was maintained for 2 h after the cold treatment. This ability of C. perfringens could improve the survival in foods and present a significant hazard.

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Abstract  

Solid bisphenol-A epoxy resin (DGEBA) of medium molecular mass was cured using o-tolylbiguanide (TBG) as cross-linking agent. In order to improve the kinetics of the reactive system, two Lewis acid catalysts (erbium(III) and ytterbium(III) trifluoromethanesulfonates) were added in proportions of 1 phr. The kinetic study was performed by dynamic scanning calorimetry (DSC) and the complete kinetic triplet (E, A and g(α)) determined. The kinetic analysis was performed with an integral isoconversional procedure (model-free), and the kinetic model was determined by the Coats-Redfern method and through the compensation effect (IKR). All the systems followed the m=1.5/n=0.5 isothermal curing model simulated from non-isothermal experiments. The addition of a little proportion of ytterbium or erbium triflates accelerated the curing process. In order to extract further information about the role of the lanthanide triflates added to epoxy/TBG systems, the kinetic results were compared with our previous kinetic studies made on DGEBA/lanthanide triflates initiated systems.

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Results of99Tc measurements between radiation and non-radiation counting methods were compared using four radiation sources for which99Tc has been previously determined with a gas-flow proportional counter or a GM counter. Each99Tc source consisted of a stainless steel planchet bound by mylar films. Seaweeds collected from the Irish Sea were analyzed and99Tc was electroplated on the planchet. The99Tc in each sample was separated and measured again by inductively coupled plasma mass spectrometry (ICP-MS). Tc was continuously removed from each sample with 2M HNO3 and 2M NaOH. After the solution containing Tc was adjusted to 0.1M HNO3, Tc was extracted on a novel extraction chromatographic resin to separate it from Ru. The total recoveries for Tc on the planchet samples were almost the same with an average of 91%. The results of99Tc measurements by both radiation and non-radiation counting methods agreed well with each other.

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An automated delayed neutron counting and instrumental neutron activation analysis system has been developed at Los Alamos National Laboratory's Omega West Reactor (OWR) to analyze samples for uranium and 31 additional elements with a maximum throughput of 400 samples per day. The system and its mode of operation for a large reconnaissance survey will be described.

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An analytical procedure for rapidly screening large numbers of oils for polychlorinated biphenyl (PCB) content has been developed and is now in routine use. Pontential levels of PCBs are inferred from chlorine concentrations as determined using the automated neutron activation analysis (NAA) facility at the Los Alamos National Laboratory Omega West Reactor. The technique is designed to screen up to 200 oil samples per eight hour working day, using a sample volume of approximately 1 milliliter. Because of the automated nature of the analysis, elements in addition to chlorine are determined, when present. These include fluorine, bromine, iodine and sulfur. U.S. National Bureau of Standards (NBS) and U. S. Environmental Protection Agency (EPA) Standard Reference Materials are routinely analyzed for quality assurance purposes. The results of our analyses of these materials for certified elements is discussed as well as results for other non-certified elements observed in the standard materials.

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Bibliometric analysis of publications of Spanish pharmacologists in the SCI (1984–89)

I. Contribution to the “Pharmacology & Pharmacy” subfield (ISI)

Scientometrics
Authors:
M. Bordons
,
F. García-Jover
, and
S. Barrigon

Abstract  

The present study is a bibliometric analysis, of publications of Spanish pharmacologists, referenced in the journals of the Pharmacology & Pharmacy subfield of the Science Citation Index- CD Edition from 1984 to 1989. During this time the scientific output of Spanish pharmacologists has been growing at an impressive rate being almost doubled. This rate being notably greater than that corresponding to publications of Spain in all science fields. This increase in scientific output was accompanied by a time-dependent decrease on year by year step basis in the expected impact factor (EIF) of publications (Articles plus Notes), from 1.71 in 1984 to 1.28 in 1989, in close correlation with an increase of mean number of authors per paper, from 3.67 to 4.16 authors/paper, respectively. Moreover, the larger the number of authors/paper, the smaller the EIF. Only 8 journals cumulated more than 50% of the papers. The scientific production was geographically localized at a high extent (Barcelona, Madrid, Valencia accounted for the 63.7% of all the papers) in governmental institutions (University, 75.2%, Hospitals, 14.1%; CSIC, 10.5%) with one large geographical area lacking any productivity.

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Journal of Thermal Analysis and Calorimetry
Authors:
R. Artiaga
,
A. Garcia
,
L. Garcia
,
A. Varela
,
J. Mier
,
S. Naya
, and
M. Grana

Abstract  

The nickel-titanium alloys are usually known as Shape Memory alloys because of their ability to return to some previously defined shape or size when subjected to the appropriate thermal procedure. Mechanical properties of a nickel titanium wire were investigated by DMTA using cylindrical tension mode. The Young"s modulus, the maximum strain and residual deformation have been calculated. Recovery of previously deformed samples was observed in constant stress temperature ramp tests. Relaxation stress behaviour at temperatures above the austenitic transformation has been studied. The strain and frequency ranges of linear response have been determined by dynamic experiments. Strain amplitude of 0.1% and frequency of 1 Hz have been chosen for the temperature ramp dynamic experiments. A big change between 65 and 95C is observed in the storage modulus. The values of E' at temperatures below and above the transition are essentially constant. Finally, the effects of the frequency at different temperatures have been examined.

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In this work a method used conventionally for ICP-MS measurements have been modified and readapted for the determination of actinides (U and Th isotopes) in refractory samples by alpha-spectrometry. The method is based in a total dissolution of the sample by alkali fusion. In the first stages of our studies, we try to digest refractory samples by leaching with aqua regia followed by the application of a liquid–liquid solvent extraction process for the sequential isolation of the uranium and thorium isotopes from the dissolved fraction. These actinides were finally electroplated in stainless steel discs and measured in an alpha-spectrometer using PIPS detectors. On the other hand, gamma measurements were carried out in aliquots of the same samples in order to check the results produced by alpha spectrometry. Clear disagreements were found between the results obtained by both techniques. This problem was solved by the application of an alkali fusion technique where a total dissolution of the sample is performed. It was found in addition that the alkali fusion is easily applicable, less time-consuming, needs less reagents than leaching and it does not require sophisticated apparatus to be executed. In this paper the whole procedure for U and Th determination in refractory samples by alpha-spectrometry with alkali fusion is presented and validated.

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Abstract  

A discussion on the influence of grafted polar groups (succinic anhydride and succinil-fluorescein) in glass transition behaviour of atactic polypropylene is shown in this work, on the basis of the reaction conditions used to obtain the modified polymers, kind and amount of grafted groups, and the degradation processes which may take place. The Box-Wilson experimental design methodology for two independent variables (reactant concentration to obtain the modified polymer) has been used to follow variations in glass transition temperatures. The existence of undesired degradation processes is considered as independent of the grafting reactions, and the model predictions seem to agree with this latter.

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