Prevalence of alcohol and tobacco use among Brazilian adolescents: a systematic review

OBJECTIVE: To analyze alcohol and tobacco use among Brazilian adolescents and identify higher-risk subgroups. METHODS: A systematic review of the literature was conducted. Searches were performed using four databases (LILACS, MEDLINE /PubMed, Web of Science, and Google Scholar), specialized websites and the references cited in retrieved articles. The search was done in English and Portuguese and there was no limit on the year of publication (up to June 2011). From the search, 59 studies met all the inclusion criteria: to involve Brazilian adolescents aged 10-19 years; to assess the prevalence of alcohol and/or tobacco use; to use questionnaires or structured interviews to measure the variables of interest; and to be a school or population-based study that used methodological procedures to ensure representativeness of the target population (i.e. random sampling). RESULTS: The prevalence of current alcohol use (at the time of the investigation or in the previous month) ranged from 23.0% to 67.7%. The mean prevalence was 34.9% (reflecting the central trend of the estimates found in the studies). The prevalence of current tobacco use ranged from 2.4% to 22.0%, and the mean prevalence was 9.3%. A large proportion of the studies estimated prevalences of frequent alcohol use (66.7%) and heavy alcohol use (36.8%) of more than 10%. However, most studies found prevalences of frequent and heavy tobacco use of less than 10%. The Brazilian literature has highlighted that environmental factors (religiosity, working conditions, and substance use among family and friends) and psychosocial factors (such as conflicts with parents and feelings of negativeness and loneliness) are associated with the tobacco and alcohol use among adolescents. CONCLUSIONS: The results suggest that consumption of alcohol and tobacco among adolescents has reached alarming prevalences in various localities in Brazil. Since unhealthy behavior tends to continue from adolescence into adulthood, public policies aimed towards reducing alcohol and tobacco use among Brazilians over the medium and long terms may direct young people and the subgroups at higher risk towards such behavior

Phase equilibrium and protein partitioning in aqueous mixtures of maltodextrin with polypropylene glycol

Equilibrium data were obtained for polypropylene glycol, PPG (400 and 3500)/maltodextrin, MD (1000 and 2000) aqueous two-phase systems at 25 degreesC. Four tie lines were measured for each system. The MD concentration in top phase is very small, and in some cases MD is almost excluded from this phase. The non random two-liquid (NRTL) model was used to correlate the equilibrium data. The partitioning behaviour of bovine serum albumin (BSA), alpha -lactoalbumin (alpha -La) and beta -lactoglobulin (beta -Lg) was studied in PPG 400/MD systems at 25 degreesC. For most cases the proteins partition preferentially to the top phase. (C) 2001 Elsevier Science Ltd. All fights reserved.46326727

Phase equilibrium in polyethylene glycol/maltodextrin aqueous two-phase systems

The polysaccharide maltodextrin (MD) can provide a low cost alternative to the fractionated dextran for the use with polyethylene glycol (PEG) in aqueous two-phase. two-polymer systems. The physical characteristics of these MD/PEG systems are similar in many respects to dextran/PEG systems. These systems' behaviour was studied at 25 degrees C and local atmospheric pressure (727 mmHg) under several concentration ratios and molecular weights of MD/PEG. Molecular weight of PEG was 1450, 8000 and 10 000; and MD's molecular weight was 2000 and 4000. This paper establishes phase diagram data, subsequently adjusting the NRTL model for the calculation of activity coefficients. The results are satisfactory and show the good descriptive quality of the model. (C) 2000 Elsevier Science Ltd. All rights reserved.42327327

PEG plus potassium phosphate plus urea aqueous two-phase systems: Phase equilibrium and protein partitioning

Liquid-liquid equilibria of poly(ethylene glycol) (PEG) + potassium phosphate + urea + water aqueous two-phase-systems were studied for different PEG molecular weights and pHs. Experimental techniques and analytical methods are described. Equilibrium data were obtained for PEG 1450, 3350, 10000) + potassium phosphate (pH 7 and 9) + urea (6 mass%) + water aqueous two-phase systems at 25 degreesC. Four tie lines were measured for each system. The partitioning behaviors of lysozyme, catalase, and beta -galactosidase were studied in these systems at 25 degreesC, at pH 7 and 9, and at the urea. concentrations 3 and 6 mass %.46225125

Polymer induced multiphase generation in water/organic solvent mixtures. Strategies towards the design of triphasic and tetraphasic liquid systems

The addition of polyethylene oxide to mixtures of CH2Cl2 and heptane caused the formation of a biphase liquid system, allowing the attainment of triphase and tetraphase liquid systems upon addition of aqueous salt solutions.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.778778