6 research outputs found
Noninvasive Solution for Electrochemical Impedance Spectroscopy on Metallic Works of Art
Full text linkMetallic works of art of cultural relevance are continuously subjected to corrosion as the environment becomes increasingly polluted. A fast and simple method to in situ assess the conservation conditions is therefore required. This paper describes the development and performance of dry and gel-based electrodes which can be used to assess the surface conservation state without the need to move the artifacts and which do not cause any damage to them. The electrodes can be used with a portable electrochemical impedance spectroscopy system, without employing electrochemical cells. The proposed solution does not provide all the information that one can obtain using an electrochemical cell, but it can discriminate between protective coatings. It can be used to assess the protective capability of corrosion product layers and natural patinas, and it can therefore enable a noninvasive routine surface assessment to be conducted that could be extremely useful for people working in the field of conservation of cultural heritag
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Full text linkMethylation of cytosines (5 me C) is a widespread heritable DNA modification. During mammalian development, two global demethylation events are followed by waves of de novo DNA methylation. In vivo mechanisms of DNA methylation establishment are largely uncharacterized. Here, we use Saccharomyces cerevisiae as a system lacking DNA methylation to define the chromatin features influencing the activity of the murine DNMT3B. Our data demonstrate that DNMT3B and H3K4 methylation are mutually exclusive and that DNMT3B is co-localized with H3K36 methylated regions. In support of this observation, DNA methylation analysis in yeast strains without Set1 and Set2 shows an increase of relative 5 me C levels at the transcription start site and a decrease in the gene-body, respectively. We extend our observation to the murine male germline, where H3K4me3 is strongly anti-correlated while H3K36me3 correlates with accelerated DNA methylation. These results show the importance of H3K36 methylation for gene-body DNA methylation in vivo
Handheld-Impedance-Measurement System with seven-decade capability and potentiostatic function
Full text linkThis paper describes design and test of a new impedance-measurement system for nonlinear devices that exhibits a seven-decade range and works down to a frequency of 0.01 Hz. The system is specifically designed for electrochemical measurements, but the proposed architecture can be employed in many other fields where flexible signal generation and analysis are required. The system employs an unconventional signal generator based on two pulsewidth modulation (PWM) oscillators and an autocalibration system that allows uncertainties of less than 3% to be obtained over a range of 1 kΩ to 100 GΩ. A synchronous demodulation processing allows the noise superimposed to the low-amplitude input signals to be made negligibl
A VOLTA AO MUNDO EM 80 DIAS: UMA APRENDIZAGEM SIGNIFICATIVA DE TERMODINÂMICA
No full textApresenta-se, neste artigo, um produto educacional elaborado na forma de sequência didática para o ensino de Termodinâmica para estudantes do ensino médio. Essa sequência didática, que aborda os conceitos relacionados com a Primeira e a Segunda Leis da Termodinâmica e, também, com máquinas térmicas, está fundamentada nos pressupostos teóricos da Teoria da Aprendizagem Significativa (TAS), de David Ausubel, e estruturada com base na obra A volta ao mundo em 80 dias, de Júlio Verne. A implementação da proposta ocorreu junto a uma turma de segunda série do ensino médio de uma escola pública do Norte do Rio Grande do Sul, e os resultados demonstram que ela pode auxiliar no desenvolvimento da aprendizagem significativa sobre o tema
Sequência didática de Termodinâmica: um material potencialmente significativo
Full text linkApresentam-se, neste artigo, os resultados de uma investigação que buscou identificar se uma sequência didática fundamentada na Teoria da Aprendizagem Significativa (TAS), de David Ausubel, e estruturada a partir da obra A volta ao mundo em 80 dias, de Júlio Verne, pode ser considerada um material potencialmente significativo para o estudo de Termodinâmica. A sequência foi implementada com um grupo de estudantes da segunda série do ensino médio de um município do interior do Rio Grande do Sul. Para a coleta de dados, utilizaram-se o diário de bordo elaborado pela professora, no decorrer da implementação, e entrevistas semiestruturadas realizadas com os estudantes. A análise dos dados guiou-se pela Análise Textual Discursiva (ATD), tendo como categorias a priori: relação dos conteúdos estudados com os conhecimentos anteriores dos estudantes; diferenciação progressiva e reconciliação integradora; materiais utilizados; participação e comprometimento nas atividades propostas; e estrutura e metodologia empregadas nas aulas. Como resultado, percebeu-se que a sequência proposta pode ser considerada um material potencialmente significativo para o estudo de Termodinâmica no ensino médio, visto que as atividades e os textos nela contidos favorecem a relação dos conhecimentos prévios dos estudantes com os assuntos abordados e possibilitam estabelecer ligações entre esses conhecimentos
Addition of either pioglitazone or a sulfonylurea in type 2 diabetic patients inadequately controlled with metformin alone: impact on cardiovascular events. A randomized controlled trial
No full textBACKGROUND AND AIMS:
Metformin is the first-line therapy in type 2 diabetes. In patients inadequately controlled with metformin, the addition of a sulfonylurea or pioglitazone are equally plausible options to improve glycemic control. However, these drugs have profound differences in their mechanism of action, side effects, and impact on cardiovascular risk factors. A formal comparison of these two therapies in terms of cardiovascular morbidity and mortality is lacking. The TOSCA.IT study was designed to explore the effects of adding pioglitazone or a sulfonylurea on cardiovascular events in type 2 diabetic patients inadequately controlled with metformin.
METHODS:
Multicentre, randomized, open label, parallel group trial of 48 month duration. Type 2 diabetic subjects, 50-75 years, BMI 20-45 Kg/m(2), on secondary failure to metformin monotherapy will be randomized to add-on a sulfonylurea or pioglitazone. The primary efficacy outcome is a composite endpoint of all-cause mortality, nonfatal myocardial infarction, nonfatal stroke, and unplanned coronary revascularization. Principal secondary outcome is a composite ischemic endpoint of sudden death, fatal and non-fatal myocardial infarction and stroke, endovascular or surgical intervention on the coronary, leg or carotid arteries, major amputations. Side effects, quality of life and economic costs will also be evaluated. Efficacy, safety, tolerability, and study conduct will be monitored by an independent Data Safety Monitoring Board. End points will be adjudicated by an independent external committee.
CONCLUSIONS:
TOSCA.IT is the first on-going study investigating the head-to-head comparison of adding a sulfonylurea or pioglitazone to existing metformin treatment in terms of hard cardiovascular outcomes. Registration: Clinicaltrials.gov ID NCT00700856
