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Search Results: 1 - 10 of 543395 matches for " C.M. Rangel "
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Semiconductor Electrochemistry and Localised Corrosion
Rangel,C.M.; Belo,M. da Cunha;
Portugaliae Electrochimica Acta , 2004,
Abstract: in the present work, the electronic structure of the passive film formed on austenitic stainless steel of the 304 type and its implications on the initiation of localised corrosion are investigated taking into account concepts developed in semiconductor physics and semiconductor electrochemistry. capacitance measurements (mott-schottky approach), show that the susceptibility of aisi 304 stainless steel to stress corrosion cracking (scc) in boiling chloride containing aqueous solutions is closely linked to the formation of a chromium rich passive oxide film with p-type semiconductivity. a small polarisation is required to drastically change the electric field at the film-electrolyte interface, as a consequence of the high doping level of the passive film. initiation of the scc phenomenon is described as the consequence of localised changes in the semiconductive properties of the passive film.
Semiconductor Electrochemistry and Localised Corrosion
C.M. Rangel,M. da Cunha Belo
Portugaliae Electrochimica Acta , 2004,
Abstract: In the present work, the electronic structure of the passive film formed on austenitic stainless steel of the 304 type and its implications on the initiation of localised corrosion are investigated taking into account concepts developed in semiconductor physics and semiconductor electrochemistry. Capacitance measurements (Mott-Schottky approach), show that the susceptibility of AISI 304 stainless steel to stress corrosion cracking (SCC) in boiling chloride containing aqueous solutions is closely linked to the formation of a chromium rich passive oxide film with p-type semiconductivity. A small polarisation is required to drastically change the electric field at the film-electrolyte interface, as a consequence of the high doping level of the passive film. Initiation of the SCC phenomenon is described as the consequence of localised changes in the semiconductive properties of the passive film.
Usando o ATSP na modelagem do problema integrado de produ??o de bebidas
Defalque, C.M.;Rangel, S.;Ferreira, D.;
TEMA (S?o Carlos) , 2011, DOI: 10.5540/tema.2011.012.03.0195
Abstract: in this paper we propose a mono-machine lot-scheduling model for a small-scale soft drink plant. the lot sizing decisions and constraints are the usual and the scheduling constraints are based on the asymmetric traveling salesman problem. to validate the model, a computational experiment was conducted using instances generated with random data and with real data taken from the literature. the instances were solved by the branch-and-cut method included in the cplex 10.0 package. the results show that the proposed model captures the main features of the production planning of a mono-machine small-scale soft drink plant. moreover, under certain circumstances, provides a better production planning than atsp na modelagem do problema de produ??o de bebidas 207 a model from the literature.
Semiconductive properties of anodic niobium oxides
,A.I. de; Rangel,C.M.; Skeldon,P.; Thompson,G.E.;
Portugaliae Electrochimica Acta , 2006,
Abstract: the semiconductive properties of anodic niobium oxides formed at constant potential and constant current density to different final voltages have been examined by mott-schottky analysis. thin anodic oxides were formed on sputtered niobium specimens at constant potential in the range of 2.5 to 10 vag/agcl in a borate buffer solution. thicker oxides were formed, also on sputtered niobium specimens, at a constant current density of 5 ma cm-2 in 0.1 m ammonium pentaborate solution to final voltages of 10, 50 and 100 v. capacitance measurements were performed in a borate buffer solution of ph 8.8, at a frequency range of 200 to 2000 hz, at a sweep rate of 5 mv s-1 from +2.5 to -1 vag/agcl. the results obtained show n-type semiconductor behaviour with a carrier density in the range of 8 ′ 1018 - 6 ′ 1019 cm-3 on films formed to 10 v. thicker films showed lower carrier densities in the range of 1 ′ 1018 - 2 ′ 1018 cm-3 with a calculated charge depletion layer of 33-36 nm.
Semiconductive properties of anodic niobium oxides
A.I. de Sá,C.M. Rangel,P. Skeldon,G.E. Thompson
Portugaliae Electrochimica Acta , 2006,
Abstract: The semiconductive properties of anodic niobium oxides formed at constant potential and constant current density to different final voltages have been examined by Mott-Schottky analysis. Thin anodic oxides were formed on sputtered niobium specimens at constant potential in the range of 2.5 to 10 V Ag/AgCl in a borate buffer solution. Thicker oxides were formed, also on sputtered niobium specimens, at a constant current density of 5 mA cm-2 in 0.1 M ammonium pentaborate solution to final voltages of 10, 50 and 100 V. Capacitance measurements were performed in a borate buffer solution of pH 8.8, at a frequency range of 200 to 2000 Hz, at a sweep rate of 5 mV s-1 from +2.5 to -1 V Ag/AgCl. The results obtained show n-type semiconductor behaviour with a carrier density in the range of 8 ′ 10(18) - 6 ′ 10(19) cm-3 on films formed to 10 V. Thicker films showed lower carrier densities in the range of 1 ′ 10(18) - 2 ′ 10(18) cm-3 with a calculated charge depletion layer of 33-36 nm.
Seguridad y Calidad en Medicina Intensiva
Romero,C.M.;
Medicina Intensiva , 2009,
Abstract: the safety and quality care are two attributes of the health care that are closely intertwined. quality is a feature of the system that delivers health care, thereby improving it, we need a proper reorganization teamwork. measurements of quality are intended to assess whether the process of health care reaches the desired objectives, while avoiding the processes that predispose to harm the patient. the critically ill patients are vulnerable to medical errors, and may experience side effects preventable, often associated with: medications, mechanical ventilation, and intravascular devices. the evidence currently available suggest that the safety and quality of care can be improved. in this article presents some of the strategies and interventions developed to optimize the processes of care in critically ill patients, and improve the safety culture in the icu.
Reimmunization after bone marrow transplantation: current recommendations and perspectives
Machado, C.M.;
Brazilian Journal of Medical and Biological Research , 2004, DOI: 10.1590/S0100-879X2004000100021
Abstract: autologous and allogeneic bone marrow transplantation (bmt) recipients lose immune memory of exposure to infectious agents and vaccines accumulated through a lifetime and therefore need to be revaccinated. diphtheria toxoid, tetanus toxoid, pertussis vaccine (children <7 years old), haemophilus influenzae type b conjugate, 23-valent pneumococcal polysaccharide, inactivated influenza vaccine, inactivated polio vaccine and live-attenuated measles-mumps-rubella vaccine are the currently recommended vaccines to be included in a vaccination program after bmt. for most of them, the best time to vaccinate, the number of vaccine doses and/or the duration of immunity after vaccination have not been established. vaccination protocols vary greatly among bmt centers, suggesting that the lack of sufficient data has not permitted the formulation of reliable recommendations. the use of other vaccines and the perspectives for different vaccination protocols are analyzed in this review.
A física de Aristóteles: uma constru??o ingênua?
Porto, C.M;
Revista Brasileira de Ensino de Física , 2009, DOI: 10.1590/S1806-11172009000400019
Abstract: in this work we make a brief exposition on aristotle's physics. we show how aristotelic science constitutes a complex export towards a rational understanding of material reality, completely integrated to an organic and comprehensive thought. we intended to show, above all, how physical and cosmological aristotelic elements come from philosophical tenets as much as from empirical observations characteristic of human experience belonging to that historic-cultural moment.
The Extent to Which Incentives Influence Primary School Teachers Job Satisfaction in Botswana
C.M. Mhozya
The Social Sciences , 2013,
Abstract: A descriptive survey using questionnaires, individual interviews and career histories of primary school teachers was conducted to investigate job satisfaction of teachers as regard to teacher incentives. The study also went further to find out whether there is any link between incentives and gender. Stratified sample from the population of primary school teachers from urban as well as rural areas in Botswana was used. Qualitative data analyses were presented through the use of frequency tables, calculation of percentages and cross tabulations. Information from all sources was triangulated. The study reveals that statistically significant number of teachers were of the view that their salaries were not enough as compared to their workloads. They clearly showed that there were no well set promotion procedures as all progressions depended solely on the school heads recommendation which were confidential and corrupt. The results also showed that teachers did not link, incentives with gender matters instead they ascribed their disadvantages to their poor qualification and hierarchical structures that limits their progression. Three recommendations were made on the basis of the findings.
Effects of Organic Manure Types on Root-Gall Nematode Disease and African Yam Bean Yield
C.M. Agu
Plant Sciences Research , 2013,
Abstract: Evaluation of the effects of different organic manures on root-gall nematode disease on African yam bean was conducted in a sandy loam soil naturally infested with a root-gall nematode, Meloidogyne incognita. The experiment was conducted in a randomized complete block design with four replications. African yam bean plant were treated with sawdust, municipal garbage, swine, compost, poultry and farmyard manures at 2.5 ton ha 1. Results showed that severe root galls occurred on plants treated with sawdust and rare galls on those treated with poultry and farmyard manures. Growth and yield characteristics of the plant were also affected by root-gall damage at the various organic manure treatments.
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