Showing papers by "Rovira i Virgili University published in 1997"

Aggregation Behavior of a Lattice Model for Amphiphiles

Abstract: We have studied aggregation of a lattice model for amphiphiles due to Larson using Monte Carlo simulations and single-chain mean-field theory Near-spherical micellar aggregates form spontaneously in the simulations In contrast to standard equilibrium theories, our simulations show a decrease in free monomer concentration above the critical micelle concentration This phenomenon is probably due to nonideal mixing effects in solution The structure of micelles of a given aggregation number predicted by the theory is in excellent agreement with simulation results The single-chain mean-field theory also accurately predicts the critical micelle concentration The mean-field prediction for the distribution of micelle size is sharper and is peaked at lower values than simulation results We suggest ways to modify the theory to improve agreement with simulation

Prevalence of DSM‐III‐R and ICD‐10 psychiatric disorders in a Spanish population of 18‐year‐olds

Abstract: The aim of this study was to estimate the current prevalence of DSM-III-R and ICD-10 psychiatric disorders in Spanish 18-year-old members of the general population. Subjects were assessed using the Schedules for Clinical Assessment in Neuropsychiatry (SCAN). Nearly 30% of the study subjects reported at least one current disorder according to ICD-10 criteria, and almost 21% reported at least one current disorder according to DSM-III-R criteria. Women had a significantly higher probability of suffering from any psychiatric disorder than men. The most common disorders were insomnia, dysthymia, major depression and simple phobia. Nearly 40% of the diagnosed subjects had one or more comorbid disorders. Comorbidity was found to be higher among female subjects. Consistent with previous risk factor research, it was found that women had higher rates of mood, anxiety and sleep disorders than men. Good communication between parents and their offspring was found to be a protecting factor for all disorders.

Trace element pollution of soils collected near a municipal solid waste incinerator: human health risk.

Abstract: Incineration is often proposed as the treatment of choice for processing municipalsolid wastes (MSW) and hazardous wastes. In spite of the known advantages ofincineration, this process produces residues, mainly the bottom ash, hazardous filterash, and additional products of flue gas cleaning operations (Jakob et al. 1995). Inrelation to those residues, the filter ash contains high concentrations of heavy metalsand polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs),whereas the bottom ash contains high concentrations of heavy metals andPCDD/PCDFs (Stern et al. 1989: Jakob et al. 1995). Moreover, some metals can bealso found as suspended particulates in air resulting from incineration of MSW (Lisk1988).Heavy metals exert a broad range of toxic effects. Elements such as cadmium orchromium are carcinogenic, other metals such as lead, mercury or thallium possessa wide spectrum of toxicity that includes neurotoxic, hepatotoxic, nephrotoxic,teratogenic or mutagenic effects.MSW incinerators represent a significant source of heavy metals released into theenvironment. Soils can be contaminated by these metals, which can thenbioaccumulate in plants and animals eventually making their way to humans by wayof the food chain or contamination of drinking water (Schuhmacher et al.1991,1993,1994; Frink 1996).Soil ingestion is usually the most significant route of exposure to soil-boundenvironmental contaminants, especially in residential areas (Kimbrough et al. 1984).It is particularly important for pollutants that may be consumed by children in theform of dust and dirt originating from soil. Although metal emissions from MSWincinerators are strictly controlled, data on metal deposition in soil samples collectednear those facilities are very limited. Particularly scarce is the information on thehuman health risks derived from ingestion of metal-polluted soils by individualsliving in the vicinity of those plants. It should be taken into account that humans maybe exposed to soil-borne metals by multiple routes including inhalation, oral and

Fibrinolysis changes in normal pregnancy.

Abstract: The aim of this study was to evaluate the changes in fibrinolysis parameters during pregnancy. Normal pregnant women (n = 60) formed the study population. Blood samples were taken in the first, second and third trimester, during delivery and three days after delivery. Fibrinolysis parameters were estimated using commercial tests. Tissue plasminogen activator, D-dimer and plasminogen activator inhibitors (PAI-1 and PAI-2) were determined. Tissue plasminogen activator and D-dimer increased after the first trimester and reached maximum levels during delivery. Plasminogen activator inhibitors type 1 and type 2 were also higher, in particular PAI-2, and reached maximum levels in the third trimester. On the third day after delivery, fibrinolysis activity recovered, but D-dimer and PAI-2 levels remained above the normal non-pregnant range.

Metal-induced developmental toxicity in mammals

Abstract: Publisher Summary This chapter reviews the developmental toxicity of various elements in mammals. Elements such as arsenic, cadmium, lead, and mercury are environmental pollutants that have profound effects upon the embryonic and fetal development. Other metals such as uranium or vanadium are developmental toxicants. Although several metals like chromium, cobalt, manganese, and zinc are considered essential for mammals, these elements may also represent a serious health hazard as a result of high environmental concentrations derived from a number of industrial activities. The toxic action of chromium (Cr) is due to its hexavalent form, which acts as a strong oxidant. Chromium (VI) crosses the placenta in humans as evidenced by elevated concentrations in the newborns. Even though cobalt (Co) is an essential trace element, excess dietary cobalt produces toxic effects in mammals. Early teratogenesis tests of Co salts were shown to be negative in hamsters, whereas Co (II) chloride caused cleft palate and delayed ossification in mouse embryos. These elements represent a serious health hazard as a result of high environmental concentrations derived from a number of industrial activities. The chapter also discusses metals such as aluminum, gallium, and lithium that are examples of current therapeutic elements but also possess potential embryotoxicity and fetotoxicity.

PCDD/Fs in soil samples collected in the vicinity of a municipal solid waste incinerator: human health risks.

Abstract: The concentrations of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) were determined in soil samples taken from 24 sites in the vicinity of a municipal solid waste incinerator (Montcada, Barcelona, Spain). Samples were collected within a radius of 3 km in each of the three main directions of the wind rose in that area. Hepta- and octa-CDDs were the predominant congeners and contributors to TEQ. PCDD/F levels ranged from 0.30 to 44.26 ng TEQ/kg (dry matter), with median and mean values of 3.52 and 6.91 ng TEQ/kg, respectively. The highest and lowest PCDD/F concentrations were found at 750 m (44.26 ng TEQ/kg) and 3000 m (0.30 ng TEQ/kg) from the stack, while the PCDD/PCDF ratio was 1.78. The health risk analysis of the data shows that the PCDD/F intake from soils is substantially lower than the tolerable daily intake for toxicologic (other than cancer) effects of PCDD/Fs.

Rapid characterization of wild and collection strains of the genus Zygosaccharomyces according to mitochondrial DNA patterns

Abstract: Several wild and collection strains of the genus Zygosaccharomyces were characterized using a rapid and simple method of restriction analysis of mitochondrial DNA. Patterns obtained with three endonucleases (HaeIII, HinfI and RsaI) made it possible to differentiate each species and to identify the wild strains, isolated from the same spoiled concentrated must, as belonging to the species Z. rouxii. The HinfI restriction enzyme produced a strain-specific pattern which allowed us to recognize that the seven wild isolates belonged to only three strains.

Effects of aluminium on the mineral metabolism of rats in relation to age.

Abstract: The present study was conducted to assess in rats the effects of chronic aluminium (Al) exposure on calcium (Ca), magnesium (Mg), manganese (Mn), copper (Cu), zinc (Zn) and iron (Fe) accumulation and urinary excretion in relation to the age of the animals Male young (21 day old), adult (8 months), and old (16 months) rats were orally exposed to 0, 50, or 100 mg Al/kg/day for a period of 65 months Urinary levels of essential elements were determined after 3 and 65 months of exposure, whereas tissue Ca, Mg, Mn, Cu, Zn and Fe concentrations were examined after 65 months of Al administration A number of age-related changes in tissue accumulation and urinary excretion of essential elements following chronic exposure to Al were found Concentrations of essential elements in most tissues of young Al-exposed rats were generally lower than those of adult and old rats The highest levels of essential elements were found in old animals Liver, testes and spleen were the tissues that showed the most remarkable increases in relation to the levels found in those tissues of young rats Adult rats showed a pattern comparable to that of old animals for mineral metabolism in brain, whereas in bone and testes the pattern of accumulation was closer to that of young rats While the urinary levels of Ca were generally reduced in the Al-exposed groups, no Al-associated changes were noted for Mg, Mn, Cu and Zn In turn, after 65 months of Al administration Fe excretion was increased in Al-treated adult and old rats The results of this study suggest that early stages of life cycle should be of special concern for Al-induced changes in the metabolism of essential elements

Quick gas chromatographic method for determining common pesticides in musts and wines

Abstract: A rapid method based on gas chromatography which determines parathion-methyl, fenitrothion, chlorpyrifos, dichlofluanid, vinclozolin, chlozolinate, procymidone and iprodione is described. It involves quantitative extraction with n-hexane and determination by capillary gas chromatography using an electron capture detector. Pesticides were satisfactorily separated in 15 min with a phenylmethylsilicone fused-silica capillary column under isothermal conditions. Quantitation was carried out using dieldrin as internal standard. The method seems appropriate for oenological laboratory work because of its simplicity and rapidity. It was successfully used to identify and quantify pesticides studied in musts and wines.

Function-Described Graphs Applied to 3D Object Representation

Abstract: The aim of this work is the characterization of a new structure called Function-Described Graphs (FDG) which can be used to represent objects in computer vision. The FDGs are useful in synthesizing structural information from a set of objects described through their structure. The FDG nodes and arcs are characterized by the probability distribution of the attributes of the ARGs nodes and arcs from where they have been synthesized. The FDG incorporates information of the family of the synthesized ARG and of the antagonistic node and arcs. In this work we apply this new structure to 3D object labeling.

A new species of Emericella from Indian soil

Abstract: Emericella pluriseminata sp. nov. (Euro- tiales, Ascomycota), isolated from Indian soil, is de- scribed and illustrated. It differs from the other spe- cies of the genus by having ascomata appearing very late, 16-spored asci, large, stellate, violet-brown asco- spores and in lacking an anamorph.

Catalytic Steam Reforming of Biomass-Derived Fractions from Pyrolysis Processes

Abstract: Biomass conversion via hydrolytic, solvolytic, and pyrolytic processes generates liquid streams that, after separation of marketable products, can be used to produce either syngas or hydrogen, a strategy being considered in this work. Catalytic steam reforming of model oxygen-containing compounds, their mixtures, bio-oil, and its fractions has been studied using Ni-based catalysts. Tests performed on a microreactor interfaced with a molecular beam mass spectrometer showed that, by proper selection of the process variables: temperature, steam-to-carbon ratio, gas hourly space velocity, and contact time, almost total conversion of carbon in the feed to CO and CO2 could be obtained. These tests also provided possible reaction mechanisms where thermal cracking competes with catalytic processes. Bench-scale, fixed bed reactor tests demonstrated high hydrogen yields from model compounds and carbohydrate-derived pyrolysis oil fractions. Reforming bio-oil or its fractions required proper dispersion of the liquid to avoid vapor-phase carbonization of the feed in the inlet to the reactor. A special spraying nozzle injector was designed and successfully tested with an aqueous fraction of bio-oil. The techno-economic assessment showed that the process could be economically viable if the lignin-derived oil fraction was sold for adhesives and only carbohydrate-derived fraction was converted to hydrogen.

Application of capillary electrophoresis in the quality control of osmotically treated water

Abstract: This paper discusses the use of capillary zone electrophoresis (CZE) with indirect UV detection for the separation and detection of ions. By use of a 70 cm×75 μm i.d. capillary at −15 kV and an electrophoretic buffer containing sodium chromate, 1-butanol, and cetyltrimethylammonium bromide as electroosmotic-flow modifier (pH 8) nine inorganic and organic anions were separated in less than 10 min. By use of the same type of capillary at 20 kV and an electrophoretic buffer containing imidazole and 18-crown-6 (pH 5) eight cations were separated in less than 5 min. The different variables that affect the separation were studied and optimized; the compounds were detected at low mg L−1 levels after hydrodynamic injection under pressure. The method was tested with osmotically treated waters, and the results compared with those obtained by ion chromatography for anion analysis and by atomic absorption spectroscopy for cation analysis.

On schema and functional architectures for multilevel secure and multiuser model federated DB systems

Abstract: This paper presents an approach for tightly federated database systems with several federated schemas that consists of a schema architecture and a functional architecture. The reference schema architecture has been extended to deal with security aspects not well solved previously. The functional architecture includes the processors needed to build the federation and the main modules of the execution architecture.

Quantitative vapor analysis using the transient response of non-selective thick-film tin oxide gas sensors

Abstract: Discusses a new method of quantitatively analyzing volatile organic compounds (VOCs) using both transient and steady-state responses of a thick-film tin oxide gas sensor array. An array of four TGS-type, non-selective, SnO/sub 2/ gas sensors and pattern recognition techniques are combined to discriminate and quantify single vapors and binary mixtures of ethanol, toluene and o-xylene. Our system recognizes the single vapors studied with a success rate of 100% and quantifies the identified vapor with a success rate of 95%. Concerning the analysis of binary mixtures, the system quantifies the previously identified mixture with a success rate of 83%.