Influência da adição de defloculante, ligante e partículas de alumina no comportamento reológico de suspensões a base de frita e caulim

Enamel suspensions were characterized according to their rheological behavior. The suspensions presented a pseudoplastic behavior, yield stress and thixotropy, with or without the presence of deffloculant. Added carboxymethylcellulose increases the apparent viscosity of enamel suspensions and interacts complexly with the deffloculant, here sodium silicate. Addition of crystalline particles of two types of alumina, used to improve the wear resistance of ceramic glazes, also change strongly the rheological behavior of the suspensions. Added high specific area, irregular alumina particles produce a higher increase of the apparent viscosity of enamel suspensions compared to rounded ones.

Influência do material do alambique na composição química das aguardentes de cana-de-açúcar

This paper describes variations in the profile of the main volatile organic compounds present in Brazilian sugar cane spirits distilled in copper and stainless steel distillers. The main organic compounds: aldehydes, ketones, carboxylic acids, alcohols and esters, were determined through High Performance Liquid Chromatography (HPLC) and High Resolution Gas Cromatography (HRGC). The spirits produced in copper distillers exhibit higher contents of aldehydes with respect to the ones produced in stainless steel. The inverse is true with respect to the higher alcohol and ester contents. No significant variation has been observed for the carboxylic acids.

Pares de nadons prematurs: afrontament de la situació i influència dels suports formals i informals

Lʼobjectiu general de la investigació és conèixer com viuen els pares lʼingrés hospitalari dʼun fill prematur en néixer, com afronten aquest fet així com la influència de les xarxes de suport formal i informal dʼaquesta població

Influència de l'educació envers prevenció d'úlceres per pressió en els coneixements dels professionals de l'equip d'infermeria i en la prevalença

Les úlceres per pressió són considerades com una de les cinc causes més comunes de dany al pacient. El 95% de les lesions, són evitables i els membres de l’equip d’infermeria són responsables de la seva prevenció. Varis estudis demostren un dèficit de coneixement dels professionals de l’equip d’infermeria envers prevenció d’UPP.En el següent projecte d’estudi, de disseny experimental longitudinal ambispectiu, es proposa avaluar l’eficàcia d’una intervenció educativa enfocada en la prevenció d’UPP i dirigida a l’equip d’infermeria per la disminució de la incidència d’UPPEl projecte consta de 6 fases. Una primera en la que es determinarà, mitjançant la revisió de les històries clíniques, la prevalença d’UPP. Posteriorment i amb l’aplicació d’un qüestionari, es valoraran els coneixements d’infermeria abans (fase 2) i després (fase 4) de la realització d’un programa educatiu (fase 3). Durant la fase 5 i amb l’ajuda d’una graella d’observació, es determinarà la incidència d’UPP durant un any des de l’aplicació del programa educatiu. A la fase 6 i passat més d’un any, es tornaran a avaluar els coneixements de l’equip d’infermeria

A influência da Química nos saberes médicos acadêmicos e práticos do século XVIII em Portugal e no Brasil

At the dawn of the eighteenth century chemistry was establishing itself as a physical science on its own right, after a long ancillary relationship with medicine and pharmacy, which had began two centuries before. This association, and the many changes that came along the scientific revolution spread into many walks of life. The Luso-Brazilian world, apparently so removed from the new developments, could not help to be touched by them, as this study shows, in which two contemporary medical authors are analysed. Both were Portuguese who had long lived in Brazil; both practised and wrote extensively on Medicine; both felt the influence of the new times, albeit in quite different ways.

Influência da acidez do meio sobre a síntese e o comportamento redox do polipirrol

The influence of acidity on the synthesis and redox behavior of polypyrrole films was studied using galvanostatic and potentiodynamic techniques employing aqueous solutions formed by H2SO4/Na2SO4 , HCl/NaCl and HCl/CsCl. The chemical structure of the films were investigated using the FTIR technique. The polymer behavior as a function of the pH used in the cyclic voltammetric measurements is explained in terms of the mechanism responsible for the charge compensation formed during the polymer chain oxidation. From the FTIR measurements, it is seen that the water nucleophilic attack during the synthesis, does not occur under the experimental conditions employed in this work.

Estudo por espectroscopia no infravermelho da interação metal-suporte em Pt/TiO2. A influência da adsorção de hidrogênio

The influence of the presence of hydrogen on Pt/TiO2 catalysts submitted to reduction treatment has been studied by FT-IR at room temperature. After submitting to LTR treatment, the hydrogen spillover has been detected and the presence of hydrogen at the bulk is shown to produce a strong absorption in the infrared spectral region. After HTR treatment, the hydrogen is strongly chemissorbed.

Estudo da influência da natureza de reticulantes e aditivos orgânicos sobre o comportamento de géis de quitosana

The physical-chemical process of swelling in water-based gel of natural polymers is investigated with the purpose of applying these systems to biomedical materials for controlled release of drugs. In this work we develop a study about the sol-gel transition of solutions of chitosan in the presence of formaldehyde and glutaraldehyde like crosslinking agents and we have determined the effect of many aditives in the time of gelification from the elaborated sistems. The phisical-chemistry process of swelling of the formed gels was evaluated in function of the degree of crosslinking of the incorporated aditives and the pH. Gelling times of chitosan solutions were obtained using viscosimetric measurement, in the pre-gel state, as well as condutivity ones.The results obtained suggest that component concentration modifies the kinetic profile of the transition and the swelling behavior. Regarding H+ content, the gels were highly susceptible to swelling in acidic conditions, which characterize this system as pH - sensitive.

O emprego de lipases como agentes de resolução cinética de enantiômeros em síntese orgânica: aspectos gerais sobre a influência do solvente

In organic synthesis, lipases are the most frequently used biocatalysts. They are efficient stereoselective catalysts in the kinetic resolution of a wide variety of chiral compounds. The discovery that enzymes possess catalytic activity in organic solvents has made it possible to address the question of reaction medium influence on enzymatic specificity. Perhaps the most exciting and significant development in this emerging area is the discovery that enzyme specificity, in particular enantioselectivity, can be affected by changing from one organic solvent to another. This article discusses the scope and possible mechanistic models of this phenomenon in hydrolases, specially lipases, as well as directions of future research in the area.

Ilustração da influência da razão de aquecimento nos resultados de termogravimetria

The effects of the heating rate on a TG curve of a sample have been widely discussed in the literature. This paper shows the influence of heating rate (beta) in thermogravimetry results when stoichiometry determinations are studied. For this purpose the compound Sm(CH3SO3)3.2(3-picNO) was considered beta of 2,5; 5; 10; 20 and 40°C min-1 in dynamic air atmosphere were obtained. The results are in agreement with proposed stoichiometry for beta equal to 2,5 and 5°C min-1. However, using a higher beta the same results were not obtained resulting in false stoichiometry determinations.

Estudo da influência do diluente reativo PGE na cinética de cura de resina epóxi utilizada em compósitos estruturais

Phenil glycidyl ether (PGE), a monofunctional diluent, has been used in epoxy resins formulations in order to increase the toughness of the epoxy molded composite. In a systematic study concerning its influence in the cure kinetics of the epoxy resin, it was used in concentrations of 2,5; 5,0; 10 and 20% in relation to a diglycidyl ether bisphenol-A (DGEBA)/diamino diphenil-sulfone (DDS) base matrix. Dynamic and isothermal scanning analysis were carried out using a differential scanning calorimety (DSC) equipment. For all the concentrations of PGE, a n order kinetics was observed, with n varing between 0,35 -- 0,91 as a function of the increase in the PGE concentration.

Morfologia e cristalinidade de hidroxicarbonato de zinco obtido via precipitação homogênea: influência dos ânions cloreto e nitrato

The effects of chloride and nitrate anions and their respective concentrations, as well as urea presence, on solid phase morphologies were investigated. Zinc hydroxide carbonate was prepared by aging diluted zinc salt solution in presence of urea at 90ºC. Samples were identified by X-ray powder diffractograms showing the characteristic patterns of hydrozincite. The crystallinity was correlated with the concentrations of reagents. Spherulitic-type aggregates and single acicular particles were obtained from diluted chloride and nitrate solutions while porous aggregates of uniform size were formed from solutions with high chloride and urea concentrations.

Caracterização de quitosana por Cromatografia de Permeação em Gel - Influência do método de preparação e do solvente

In this work, samples of chitosan obtained in different conditions were characterized by molecular weight distribution, using Gel Permeation Chromatography (GPC), in two different solvents. It was observed that the increase in the number of deacetylation steps promotes a increase in the degree of deacetylation followed by a decrease in the average of molecular weight and polydispersion. The GPC curves obtained for chitosan samples in the two solvents used (CH3COOH 0.30 mol/dm³ - CH3CONa 0.20 mol/dm³ and CH3COOH 0.10 mol/dm³ - NaCl 0.20 mol/dm³) showed small difference in elution volume, but significant changes in the average molecular weight (Mn and Mw) and polydispersion that, in agree with the values of Huggins constant, present evidences of chitosan aggregates formation in the second solvent.

Influència del nombre d'usuaris en sistemes de localització en interiors basats en Wi-Fi

El present estudi descriu el procés de creació d'un sistema de localització en interiors que permet investigar les possibles diferències de la precisió de les localitzacions en entorns buits i amb presència d'altres persones. Posteriorment es presenten una sèrie de proves realitzades, s'exposen els seus resultats, així com les conclusions sobre com influencia el nombre d'usuaris a la precisió del sistema.

Influència i presència de l’Institut Rousseau de Ginebra en la pedagogia catalana del primer terç del segle XX

Les influències dels corrents pedagògics internacionals i l’impacte de la pedagogia activa en l’impuls de la renovació pedagògica catalana del primer terç del segle XX han estat objecte de molts estudis, que ens permeten traçar una cartografia pedagògica europea per comprendre les claus d’aquest ampli i profund moviment de renovació que va abonar els difícils terrenys de l’educació europea des de les darreres dècades del segle XIX. En aquest mapa, caldria marcar Ginebra amb traç gruixut, unida amb Catalunya i, per extensió, Espanya. L’estudi de les fonts documentals dels arxius de l’emblemàtic Institut Jean-Jacques Rousseau, creat a Ginebra l’any 1912, i la revisió de diverses recerques i publicacions ens possibiliten una nova lectura amb l’objectiu d’aportar més elements per valorar la influència de l’institut ginebrí sobre la pedagogia catalana del primer terç del segle XX.