Efeito da velocidade de aquecimento nas propriedades de produtos da cerâmica estrutural

Heating rate is one of the main variables that determine a fire cycle. In industrial processes that use high temperatures, greater fire great can reduce the cost of production and increase productivity. The use of faster and more efficient fire cycles has been little investigated by the structural ceramic industry in Brazil. However, one of the possibilities that aims at modernizing the sector is the use of roller kilns and the inclusion of natural gas as fuel. Thus, the purpose of this study is to investigate the effect of heating rate on the technological properties of structural ceramic products. Clay raw materials from the main ceramic industries in the state of Rio Grande do Norte were characterized. Some of the raw materials characterized were formulated to obtain the best physical and mechanical properties. Next, raw materials and formulations were selected to study the influence of heating rate on the final properties of the ceramic materials. The samples were shaped by pressing and extrusion and submitted to rates of 1 °C/min, 10 °C/min and 20 °C/min, with final temperatures of 850 °C, 950 °C and 1050 °C. Discontinuous cycles with rates of 10 °C/min or 15 °C/min up to 600 °C and a rate of 20 °C/min up to final temperature were also investigated. Technological properties were determined for all the samples and microstructural analysis was carried out under a number of fire conditions. Results indicate that faster and more efficient fire cycles than those currently in practice could be used, limiting only some clay doughs to certain fire conditions. The best results were obtained for the samples submitted to slow cycles up to 600 °C and fast fire sinterization up to 950 °C. This paper presents for the first time the use of a fast fire rate for raw materials and clay formulations and seeks to determine ideal dough and processing conditions for using shorter fire times, thus enabling the use of roller kilns and natural gas in structural ceramic industries

Prevalência de excesso de peso em pré-escolares na cidade do Natal

Obesity is currently considered a public health problem and there has been growing interest in the study of various aspects related to this infirmity such as: epidemiology, diagnosis, treatment, prevention and others. Thus, the purpose of this study was to determine the prevalence of weight excess and overweight in preschoolers in Natal, Brazil and relate them to variables such as gender, age, type of school (public or private) and zones of the city (east/south and north/west). This is a transversal study, carried out in Natal, Brazil between August and September 2004, in 20 public and 20 private schools/day care centers selected by the systematic sampling method. We measured the weight and height of 3721 students between the ages of 2 and 6 years. The children were stratified, according to age, into age group 1 (2 to 4 years) and age group 2 (5 and 6 years) and according to the region of the school, into north/west and east/south zones, the regions with the smallest and highest quality of life indices in the city, respectively. Children were considered to have weight excess when BMI ≥ 85th percentile, including those with BMI ≥ 95th percentile and overweight when BMI ≥ 95th percentile. The prevalence of weight excess was 26.5%, and of overweight 12.4%. There was greater prevalence of weight excess in the private schools and in the east/south zones. Overweight displayed the same epidemiologic profile, with a greater prevalence in private schools and in the east/south zones. The prevalence of weight excess in preschoolers in Natal, Brazil is high and is related, above all, to private schools and to those located in the highest quality of life areas. Therefore, prevention programs should be implanted in elementary schools in order to decrease weight excess and possible associated co-morbidities. This research project met the norms established by PPGCSa/UFRN and aimed at promoting the interrelation between different researchers and between different fields of knowledge, using multi and interdisciplinary concepts. This study was enriched by the interaction between the following professionals: pediatrician, pediatric gastroenterologist and physician nutrition specialist, pediatric endocrinologist, epidemiologist and biostatistician

Excesso de peso em região do nordeste brasileiro: contraste entre escolares de rede pública e privada de ensino

The prevalence of obesity has been increased in the last three decades. It is already considered as epidemic by the World Health Organization and reaches around 300 million people worldwide. The weight gain in all ages is related to a sedentary way of life and hyper caloric food ingestion at the modern society. Obesity is a chronic disease and leads to high blood pressure, diabetes, cardiovascular diseases and cancer. The aim of this study was to evaluate the prevalence of weight excess among student in Natal schools and to analyze its association with age, gender, school category and geographic localization in city zones. This was a transversal study which enrolled 1927 children. 1084 of these were between 6 and 8 years-old (group 1) and 843 were 9 to 10 years-old (group 2). 895 of the total children studied in private schools and 1032 studied in public schools. 33,6% of the students had body mass index equal or above the 85th percentile and were considered as having weight excess. There was no statistical difference in this prevalence considering neither gender nor age. The weight excess prevalence in private schools was 54,5% and in public ones was 15,6% (p<0,01; OR=6,49). Weight excess was also more prevalent in the south and east city zones (41,3%) which have better quality of life index than in the north and west zones (28,4%) (p<0,01). In conclusion, the weight excess prevalence among students is found to be high in Natal and programs of intervention and prevention of obesity are necessary. The higher prevalence in private schools as in the wealthier city zones reflects the link between obesity and high socioeconomic level found in countries in developing. This was an interdisciplinary work with participation of epidemiology, child nutrition and pediatric endocrinology following the recommendations and principles of the Post graduation Program in Health Sciences of the Federal University of Rio Grande do Norte

Síndrome metabólica e fatores de risco relacionados em crianças e adolescentes com excesso de peso na cidade do Natal

Nas últimas décadas, houve grande aumento da prevalência de obesidade, inclusive na faixa etária pediátrica. Com isso, aumentou o número de crianças e adolescentes afetados por síndrome metabólica (SM), diabetes tipo 2 (DM2) e doenças cardiovasculares (DCV), doenças anteriormente consideradas quase exclusivas de adultos. Os objetivos do estudo foram identificar e correlacionar marcadores antropométricos (IMC- índice de massa corpórea, CA- circunferência abdominal, RCQ- razão cintura/quadril, RCArazão cintura altura e PSE- prega subescapular), PAS e PAD- pressão arterial sistólica e diastólica, respectivamente, e laboratoriais (CT- colesterol total, HDL, LDL, TGL- triglicérides, I/G- razão insulina glicose, HOMA- homeostatic model assessment for insulin resistance) de risco para o desenvolvimento de SM e observar a sua prevalência em crianças e adolescentes com excesso de peso. Foi conduzido estudo transversal, em amostra aleatória, de conveniência, onde foram avaliadas 60 crianças e adolescentes com excesso de peso, atendidas no ambulatório de endocrinologia pediátrica do Hospital de Pediatria da Universidade Federal do Rio Grande do Norte (UFRN) com idade mínima e máxima de 7 e 15 anos, de maio de 2009 a abril de 2010. Foram admitidos os indivíduos que apresentavam sobrepeso (IMC P > 85 e < 95) ou obesidade (IMC P > 95) (CDC, 2000) e história familiar positiva para DM2 em parentes de primeiro ou segundo grau ou algum dos sinais de resistência insulínica (acantose, hipertensão arterial, dislipidemia, síndrome de ovários policísticos). 2 O componente individual para SM mais prevalente foi o percentil da CA ≥ 90 (58,3%), seguido de HDL ≤ 40 mg/dl (36,6%). Na regressão linear simples, observaram-se as variações para mais nos parâmetros laboratoriais e de PA para cada unidade de aumento de IMC, CA, RCA, RCQ e PSE, sendo significantes as seguintes correlações: CA com TGL, HOMA IR, I/G, PAS e PAD; RCQ com TGL, HOMA, I/G, LDL e glicemia; RCA com TGL; PSE com TGL, HOMA-IR, I/G e PAS; e IMC com HOMA IR, I/G, PAS e PAD. De acordo com os critérios da IDF (Federação Internacional de Diabetes International Diabetes Federation) 2007, o diagnóstico de SM foi encontrado em seis indivíduos (10%). Do total, oito (13,3%), estavam em situação de sobrepeso e 52 (86,6%), obesos. As evidências de correlação CA e RCQ, medidas de obesidade centrípeta, com vários marcadores como TGL e HOMA, já sabidamente relacionados à SM, chamam atenção para a necessidade de utilização dessas medidas de forma mais rotineira na prática pediátrica, por serem de fácil obtenção, baixo custo e método não invasivo. Os valores de CA, RCQ, RCA e PSE, quando elevados devem justificar maior detalhamento na avaliação laboratorial de possível resistência insulínica. É importante a identificação de crianças e adolescentes que preencham os requisitos para o diagnóstico da SM, pois são indivíduos de maior risco metabólico e devem ser adequadamente acompanhados.

Estilo de vida individual de universitários jovens com excesso de peso da Universidade Católica de Murcia-Espanha

Individual lifestyle includes health and risk behaviors that can altar health status. Excess weight is a public health problem of modern civilization and there is an estimated mean prevalence of 45% in European countries. In Spain, the Murcia Region is an area of high morbidity and mortality from cardiovascular disorders. In this study we assess the differences in health and risk behaviors in ove/weight and normal weight undergraduates at the Universidad Católica San Antonio de Murcia (UCAM). Methods: Transversal design of parallel groups (overweight - cases and normal weight - control) , formed using the anthropometric technique. A questionnaire applied to a sample of 471 undergraduates of either sex, between the ages of 18 and 29 years, enrolled in 4 bachelor degree courses (ADE, CA, PER, PUB) at UCAM. We performed a standardized measurement of body mass (weight in kg), height (in meters) using a Seca® scale with calibrated stadiometer, waist and hip circumferences (in cm) with an inelastic tape and skinfolds thickness (triceps and subscapular in mm) with a Holtain® caliper, to calculate body mass index (BMI), waist-to-hip ratio (WHR) and the sum of skinfolds (SSF). We applied a lifestyle questionnaire about alcohol and tobacco consumption, knowledge and behaviors related to health indicators (arterial pressure and cholesterol), diet and physical activity. The information was collected in April and May, 2001 at the UCAM laboratory of Applied Nutrition. Statistical analysis: analysis of independent groups, contingency tables that reveal which qualitativa variables show differences and associations between the groups, Pearson's chi-square,and a significance levei of p < 0.05 followed by a residual analysis (1.96). Descriptive statistics (mean and standard deviation) were used to establish the two groups: case and contrai with 65 men and 26 women each who had BMI < 25 kg/m2. Results: A total of 65 of the men assessed (14%) and 26 (6%) of the women were overweight. Mean body mass index of the case group was 27. 78 ±: 2.83 kg/m2 in the men and 26.26 ± 1.37 kg/m2 in the women, while contrai group men had mean BMI of 22.36 ± 1.72 kg/m2, while for the women it was 20.76 ±: 2.13 kg/m2. The self-declared values of weight and height were underestimated, but with high accuracy, sensitivity and specificity. Thus, these can be used to calculate the BMI of overweight Spanish undergraduates. Regular vigorous physical activity was observed only in normal weight men. The analysis showed the following significant differences for the qualitativa variables of the two groups. The contrai group was interested in arterial hypertension, believed that they were not overweight, that they had no abdominal fat, and had not considered controlling 'fatty food consumption. Those who thought of controlling it sometimes, did so without professional help. However, part of the overweight group believed that they were overweight and had abdominal fat between average and considerable, had often or always considered controlling fatty foods and had often or always tried to control consumption with the help of professionals. They had always thought of engaging in physical activities, unlike the normal weight individuals. Nearly all (95%) of the overweight undergraduates and most (75%) of the normal weight group reported that they sometimes or always controlled fatty food ingestion. Mean physical activity was nearly twice as high in the summer than in the winter. Conclusions: The overweight undergraduates in this sample displayed a lifestyle with a greater number of healthy behaviors when compared to normal weight individuals

A produção biopolítica do corpo saudável: mídia e subjetividade na cultura do excesso e da moderação

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

A Produção biopolítica do corpo saudável: mídia e subjetividade na cultura do excesso e da moderação

Recognizing the plans left by Foucault as legitimate, for those that the struggle to fight against all forms of way of life subjection takes an important role on human being existence, this thesis questions the impacts of body planning on health specialized media on the production of the contemporary subjectivity. Having the Saúde! magazine as this thesis empirical field, it discusses the subjectivity processes centered on the realization of many bodily practices destined to a perfect body self-construction, finding suitable conditions for a narcissistic development of the new ways of social regulation on hypermodern societies. Our central argument, refering to a specific reflection about the body, media and subjectivity, is that the body promoting over the health specialized media makes possible the creation of new existential territories, configuring the healthy body bio-political production by a subjectivity process open to experimenting and to self-invention. Bodily subjectivity process centered on body self-construction, simultaneously generating human subjectivity singularization and massification, evidencing escape routes to build a body health existential perspective. In this thesis we seek to point not only the historically hegemonic forms of being healthy, but mainly the forces that nowadays question these forms, making possible the thought of other ways to live the health of the body, starting from the subjectivity singularization

Enfermagem na atenção primária em saúde no screening de adolescentes com excesso de peso

One of the Primary Health Care strategies for adolescent health is the growth and development follow-up and the early detection of overweight adolescents. Even though the School Health Program in Brazil proposes to evaluate the nutritional state of the school population in the corresponding community health units, not all cities have adhered to the Program and many nurses do not recognize overweight as a problem in their territory. The objective of the study was to identify the nurse´s participation in the screening of overweight adolescent students in their work territory. Cross sectional study conducted in eight state supported schools of the municipality of Natal/RN and in four Primary Health Units. The total student population was 27.277. A stratified sample was statistically calculated based on the student population of the four city geographical zones: 112 North , 74 West; 108 East; and 78 South, totalizing 372 adolescents. The students were selected by a probability process where eight schools were first selected, two per district, until the number per subsample in each district was reached. Four primary health nurses, responsible for the health units were included. Two instruments were used for data collection, a screening questionnaire and a semi-structured interview form for questioning of the nurses. The content of both instruments was validated. Anthropometric and health data were collected from the students and analyzed with descriptive and analytical statistics. Interview data were transcribed and submitted to content analysis. The nursing diagnosis of overweight was identified in 50 (13,5%) of the adolescents and its association with consumption of foods that have cardiovascular risk (canned foods, pasta and fried food). An association of the nursing diagnosis was identified with family history (diabetes, hypertension, obesity, and kidney disease). The nurses judged that care of overweight adolescents was important but noted difficulties because of the absence of this population in the health units, because of their work overload, and the lack of school articulation. The nurses do not have impacting actions with this population and delegate the responsibility to other professionals. It is concluded that overweight is a nutritional problem relevant to the adolescent school population in Natal/RN, with a 13,5% prevalence and that it is related to food consumption with cardiovascular risk and family health history. The nurses consider overweight as an important public health problem but do not envision ways to maintain linkage with adolescents and with the school to promote the needed care

Controle vetorial de velocidade de uma máquina de indução sem mancais trifásica com bobinado dividido utilizando estimação neural de fluxo

This work describes the study and the implementation of the vector speed control for a three-phase Bearingless induction machine with divided winding of 4 poles and 1,1 kW using the neural rotor flux estimation. The vector speed control operates together with the radial positioning controllers and with the winding currents controllers of the stator phases. For the radial positioning, the forces controlled by the internal machine magnetic fields are used. For the radial forces optimization , a special rotor winding with independent circuits which allows a low rotational torque influence was used. The neural flux estimation applied to the vector speed controls has the objective of compensating the parameter dependences of the conventional estimators in relation to the parameter machine s variations due to the temperature increases or due to the rotor magnetic saturation. The implemented control system allows a direct comparison between the respective responses of the speed and radial positioning controllers to the machine oriented by the neural rotor flux estimator in relation to the conventional flux estimator. All the system control is executed by a program developed in the ANSI C language. The DSP resources used by the system are: the Analog/Digital channels converters, the PWM outputs and the parallel and RS-232 serial interfaces, which are responsible, respectively, by the DSP programming and the data capture through the supervisory system

Controle vetorial de velocidade de um motor de indução trifásico com estimação neural de fluxo

This work describes the study and the implementation of the speed control for a three-phase induction motor of 1,1 kW and 4 poles using the neural rotor flux estimation. The vector speed control operates together with the winding currents controller of the stator phasis. The neural flux estimation applied to the vector speed controls has the objective of compensating the parameter dependences of the conventional estimators in relation to the parameter machine s variations due to the temperature increases or due to the rotor magnetic saturation. The implemented control system allows a direct comparison between the respective responses of the speed controls to the machine oriented by the neural rotor flux estimator in relation to the conventional flux estimator. All the system control is executed by a program developed in the ANSI C language. The main DSP recources used by the system are, respectively, the Analog/Digital channels converters, the PWM outputs and the parallel and RS-232 serial interfaces, which are responsible, respectively, by the DSP programming and the data capture through the supervisory system

Controle vetorial para velocidade de um motor de indução trifásico utilizando estimador filtro de Kalman

This paper describes the study, computer simulation and feasibility of implementation of vector control speed of an induction motor using for this purpose the Extended Kalman Filter as an estimator of rotor flux. The motivation for such work is the use of a control system that requires no sensors on the machine shaft, thus providing a considerable cost reduction of drives and their maintenance, increased reliability, robustness and noise immunity as compared to control systems with conventional sensors

Otimização do processo de recuperação do cromo de efluentes de curtumes por microemulsões no extrator Morris

The tanning industries are those which transform animal hide or skin into leather. Due to the complexity of the transformation process, greater quantities of chemicals are being used which results in the generation of effluents with residual solids. The chromium in the residual waters generated by tanning tend to be a serious problem to the environment, therefore the recovery of this metal could result in the reduction of manufacturing costs. This metal is usually found in a trivalent form which can be converted into a hexavalent compound under acidic conditions and in the presence of organic matter. The present study was carried out with the objective to recover chromium through an extraction/re-extraction process using micro emulsions. Micro emulsions are transparent and thermodynamically stable system composed of two immiscible liquids, one forming the continuous phase and the other dispersed into micro bubbles, established by an interfacial membrane formed by surface active and co-surface active molecules. The process of recovering the chromium was carried out in two stages. The first, an extraction process, where the chromium was extracted in the micro emulsion phase and the aqueous phase in excess was separated. In the second stage, a concentrated acid was added to the micro emulsion phase rich in chromium in order to obtain a Winsor II system, where the water that formed in the micro emulsion phase separates into a new micro emulsion phase with a higher concentration of chromium, due to the lowering of the hydrophiles as well as the ionisation of the system. During the experimental procedure, a study was initiated with a synthetic solution of chromium sulphate passing onto the effluent. A Morris extractor was used in the extraction process. Tests were carried out according to the plan and the results were analysed by statistical methods in order to optimise the main parameters that influence the process: the total rate of flow (Q), stirring speed (w) and solvent rate (r). The results, after optimization, demonstrated that the best percentuals in relation to the chromium extraction (99 %) were obtained in the following operational conditions: Q= 2,0 l/h, w= 425 rpm and r= 0,375. The re-extraction was carried out at room temperature (28 °C), 40 °C and 50°C using hydrochloric acid (8 and 10 M) and sulphuric acid (8 M) as re-extracting agents. The results obtained demonstrate that the process was efficient enough in relation to the chromium extraction, reaching to re-extraction percentage higher than 95 %.

Função de distribuição generalizada aplicada à velocidade de rotação estelar

In the present work we use a Tsallis maximum entropy distribution law to fit the observations of projected rotational velocity measurements of stars in the Pleiades open cluster. This new distribution funtion which generalizes the Ma.xwel1-Boltzmann one is derived from the non-extensivity of the Boltzmann-Gibbs entropy. We also present a oomparison between results from the generalized distribution and the Ma.xwellia.n law, and show that the generalized distribution fits more closely the observational data. In addition, we present a oomparison between the q values of the generalized distribution determined for the V sin i distribution of the main sequence stars (Pleiades) and ones found for the observed distribution of evolved stars (subgiants). We then observe a correlation between the q values and the star evolution stage for a certain range of stel1ar mass

Criação da matéria em cosmologias com velocidade da luz variável e eletrônico não-linear

In this work we obtain the cosmological solutions and investigate the thermodynamics of matter creation in two diferent contexts. In the first we propose a cosmological model with a time varying speed of light c. We consider two diferent time dependence of c for a at Friedmann-Robertson- Walker (FRW) universe. We write the energy conservation law arising from Einstein equations and study how particles are created as c decreases with cosmic epoch. The variation of c is coupled to a cosmological Λ term and both singular and non-singular solutions are possible. We calculate the "adiabatic" particle creation rate and the total number of particles as a function of time and find the constrains imposed by the second law of thermodynamics upon the models. In the second scenario, we study the nonlinearity of the electrodynamics as a source of matter creation in the cosmological models with at FRW geometry. We write the energy conservation law arising from Einstein field equations with cosmological term Λ, solve the field equations and study how particles are created as the magnetic field B changes with cosmic epoch. We obtain solutions for the adiabatic particle creation rate, the total number of particles and the scale factor as a function of time in three cases: Λ = 0, Λ = constant and Λ α H2 (cosmological term proportional to the Hubble parameter). In all cases, the second law of thermodynamics demands that the universe is not contracting (H ≥ 0). The first two solutions are non-singular and exhibit in ationary periods. The third case studied allows an always in ationary universe for a suficiently large cosmological term

Modelos cosmológicos com velocidade da luz variável

Conselho Nacional de Desenvolvimento Científico e Tecnológico