Influência da adição no comportamento reológico da pasta autoadensável de alto desempenho

Influence of admixture on the rheological behavior of high performance self-compacting paste. This research proposes to study the influence of the specific area, mould and surface texture of admixtures on the rheological behavior of high performance self-compacting paste (HPSCP). The selected admixtures are calcareous filler and basalt filler, which are industrial residues, thus contributing to sustainable development. The paste is made up of cement, silica fume, calcareous filler or basalt filler, water and superplasticizer additive. For this study, the water/cement ratios are fixed = 0.40 L kg(-1); silica fume/cement = 0.10 kg kg(-1); the filler/cement and superplasticizer/cement ratios are determined through Marsh cone and mini-slump tests. The results show that for same filler/cement ratios, the ratios of superplasticizer to paste with calcareous filler are significantly lower than those of paste with basalt filler. The results show that the specific area, mould and surface texture of these admixtures significantly influence the rheological behavior of HPSCP.

A Comparison of Deep Drawing and Ironing of Metal Alloy Strip Produced conventionally and Non-conventionally via Semi Solid Material Processing

A semi solid thin strip continuous casting process was used to obtain 50%wt Pb/50%wtSn strip by single and twin roll processing at speed of 15 m/min. A 50%wt Pb/50%wtSn plate ingot was also cast for rolling conventionally into strips of 1.4 mm thickness and 45 mm width for comparison with those achieved non-conventionally. This hypoeutectic alloy has a solidification interval and fusion temperature of approximately 31 degrees C and 215 degrees C respectively. The casting alloy temperature was around 280 degrees C as measured by a type K immersion thermocouple prior to pouring into a tundish designed to maintain a constant melt flow on the cooling slope during semi solid material production. A nozzle with a weir ensures that the semi solid material is dragged smoothly by the lower roll, producing strip with minimum contamination of slag/oxide. The temperatures of the cooling slope and the lower roll were also monitored using K type thermocouples. The coiled semi solid strip, which has a thickness of 1.5 mm and 45 mm width, was rolled conventionally in order to obtain 1.2 mm thick strip. The coiled thixorolled strip had a thickness of 1.2 mm and achieved practically the same width as the conventional strips. Blanks of 40 mm diameter were cut from the strips in a mechanical press, ready for deep drawing and ironing for mechanical characterization. All the strips achieved from non-conventional processing had the same mechanical performance as those achieved conventionally. The limiting drawing ratio (LDR) achieved was approximately 2.0 for all strips. Microscopy examination was made in order to observe phase segregation during processing.

Waveshapes of continuing currents and properties of M-components in natural positive cloud-to-ground lightning

This work analyses the waveshapes of continuing currents and parameters of M-components in positive cloud-to-ground (CG) flashes through high-speed GPS synchronized videos. The dataset is composed of only long continuing currents (with duration longer than 40 ms) and was selected from more than 800 flashes recorded in Sao Jose dos Campos (45.864 degrees W, 23.215 degrees S) and Uruguaiana (29.806 degrees W, 57.005 degrees S) in Southeast and South of Brazil, respectively, during 2003 to 2007 summers. The videos are compared with data obtained by the Brazilian Lightning Location System (BrasilDAT) in order to determine the polarity of each flash and select only positive cases. There are only two studies of waveshapes of continuing currents in the literature. One is based on direct current measurements of triggered lightning, in which four different types of waveshapes were observed; and the other is based on measurements of luminosity variations in high-speed videos of CG negative lightning, in which besides the four types above mentioned two additional types were observed. The present work is an extension of the latter, using the same method but now applied to obtain the waveshapes of positive CG lightning. As far as the authors know, this is the first report on M-components in positive continuing currents. We also have used the luminosity-versus-time graphs to observe their occurrence and measure some parameters (duration, elapsed time and time between two successive M-components), whose statistics are presented and compared in detail to the data for negative flashes. We have plotted a histogram of the M-components elapsed time over the total duration of the continuing current for positive flashes, which presented an exponential decay (correlation coefficient: 0.83), similar to what has been observed for negative flashes. (C) 2008 Elsevier B.V. All rights reserved.

Avaliação dos efeitos do biperideno, diazepam e neuropeptídeos S sobre a memória e a ansiedade na tarefa do labirinto em T elevado em camundongos

Anxiety is an emotional phenomenon, and normally it is interpreted as an adaptative behavior front to adversities. In its pathological form, anxiety can severely affect aspects related to the personal and professional life. Studies have shown a close relationship between anxiety disorders and aversive memory processing. Considering that the pharmacotherapy of anxiety disorders is still limited, innovative anxiolytic agents are needed. In this regard, neuropeptides systems are interesting therapeutic targets to the treatment of psychopathologies. Neuropeptide S (NPS), a 20-aminoacid peptide, is the endogenous ligand of a G-protein coupled receptor (NPSR), which has been reported to evoke hyperlocomotion, awakefull states, besides anxiolysis and memory improvements in rodents. This study aimed to investigate the effects of biperiden (BPR; an amnesic drug), diazepam (DZP; an anxiolytic drug) and NPS at three distinct times: pre-training, post-training, and pre-test, in order to assess anxiety and memory process in the same animal model. The elevated Tmaze (ETM) is an apparatus derived from the elevated plus-maze test, which consists of one enclosed and two open arms. The procedure is based on the avoidance of open spaces learned during training session, in which mice were exposed to the enclosed arm as many times as needed to stay 300 s. In the test session, memory is assessed by re-exposing the mouse to the enclosed arm and the latency to enter an open arm was recorded. When injected pre-training, BPR (1 mg/kg) impaired learning and memory processing; DZP (1 and 2 mg/kg) evoked anxiolysis, but only at the dose of 2 mg/kg impaired memory; and NPS 0.1 nmol induced anxiolysis without affecting memory. Post-training injection of DZP (2 mg/kg) or BPR (1 and 3 mg/kg) did not affect memory consolidation, while the post-trainning administration of NPS 1 nmol, but not 0.1 nmol, improved memory in mice. Indeed, pre-trainning administration of NPS 1 nmol did not prevent memory impairment elicited by BPR (2 mg/kg, injected before training). In the open field test, BPR 1 mg/kg and NPS 1 nmol induced hyperlocomotion in mice. In conclusion, the proposed ETM task is practical for the detection of the anxiolytic and amnesic effects of drugs. The anxiolytic and memory enhancement effects of NPS were detected in the ETM task, and reinforce the role of NPS system as an interesting therapeutic target to the treatment of anxiety disorders

Positive leader characteristics from high-speed video observations

Based on analyses of high-speed video recordings of cloud-to-ground lightning in Brazil and the USA, the characteristics of positive cloud-to-ground (+CG) leaders are presented. The high frame rates permitted the average, 2-dimensional speeds of development along the paths of the channels to be resolved with good accuracy. The values range from 0.3 to 6.0 x 10(5) ms(-1) with a mean of 2.7 x 10(5) ms(-1). Contrary to what is usually assumed, downward +CG leader speeds are similar to downward -CG leader speeds. Our observations also show that the speeds tend to increase by a factor of 1.1 to 6.5 as they approach the ground. The presence of short duration, recoil leaders (RLs) during the development of positive leaders reveal a highly branched structure that is not usually recorded when using conventional photographic and video cameras. The existence of the RLs may help to explain observations of UHF-VHF radiation during the development of +CG flashes.

Preparation and characterization of cellulose/hydrous niobium oxide hybrid

A composite of cellulose extracted from bagasse with Nb2O5 center dot nH(2)O in three different proportions (16.67, 37.5 and 50.0 wt%) was prepared using the co-precipitation method. The materials were characterized by X-ray diffractometry (XRD), Fourier transform infra-red spectroscopy (FTIR), thermogravimetric analysis (TG/DTG), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). TG data obtained show that the presence of inorganic material influenced slightly the stability of the hybrid material. The precipitation of 16.67 wt.% of oxide was sufficient to inhibit the combustion peaks present in the DSC curve of cellulose. This work will help find new applications for these materials. Published by Elsevier Ltd.

Seleção de progênies de meios-irmãos do composto Isanão VF-1 de milho na safra e safrinha

O aumento significativo da produção de milho na segunda safra no Brasil, principalmente no centro-sul do país, têm estimulado os programas de melhoramento da cultura a selecionar genótipos que sejam adaptáveis às condições climáticas das diferentes épocas de semeadura. Nesse sentido, o objetivo do presente trabalho foi quantificar a interação progênies x épocas de semeadura e verificar seus reflexos no progresso genético com o uso de índice de seleção multivariado para seleção de progênies do Composto Isanão VF-1 de milho. As semeaduras foram realizadas na segunda safra em 2004 e na primeira safra do ano agrícola 2004/05. Foram utilizadas 71 progênies de meios irmãos avaliadas em blocos ao acaso, com três repetições. Os caracteres avaliados foram: altura de plantas, altura de espigas, tombamento, prolificidade e rendimento de grãos. Realizaram-se a decomposição da interação progênies x épocas e foram estimados os ganhos pelo índice de seleção descrito por Mulamba e Mock. Houve predomínio da interação do tipo simples para maioria dos caracteres, exceto para prolificidade, que revelou 86% de interação do tipo complexa. Pelo índice de Mulamba e Mock, os ganhos proporcionais mais adequados para o conjunto de caracteres avaliados foi obtido pelos pesos econômicos atribuídos por tentativas. Os ganhos preditos foram de 1,41, 0,86, -13,03, 9,54 e 16,12% para altura de planta, altura de espiga, tombamento, prolificidade e rendimento de grãos, respectivamente.

Cinza de casca de arroz (CCA) altamente reativa: método de produção e atividade pozolânica

Este trabalho apresenta um método de produção para a obtenção de cinza de casca de arroz (CCA) de elevada reatividade a partir de um processo de combustão não controlado. São detalhados os processos de obtenção da CCA, assim como sua atividade pozolânica. Pela Análise Termogravimétrica (TGA), foi possível quantificar o consumo de portlandita por parte da CCA, ou seja, a reação pozolânica. Adicionalmente, foram preparadas argamassas com diferentes porcentagens de CCA (5%, 10% e 15%) com o objetivo de comprovar sua influência nas propriedades mecânicas. Os resultados obtidos mostram que a CCA em estudo apresenta elevada reatividade, podendo ser utilizada como uma fonte alternativa da sílica ativa (SA).

Transferência de oxigênio em reatores de leito fluidizado com circulação em tubos concêntricos em meios bifásico e trifásico com variação da relação entre diâmetros

A eficiência do reator de leito fluidizado com circulação em tubos concêntricos depende das condições hidrodinâmicas que influem na transferência de oxigênio ao biofilme. Este trabalho investigou a influência da relação entre diâmetros dos tubos e da concentração de meio suporte (areia), sobre o coeficiente global de transferência de oxigênio (K La). Os ensaios - em reatores de 2,6 m de altura, com diâmetro externo de 250 mm e internos de 100, 125, 150 e 200 mm - empregaram vazões de ar até 2.500 L.h-1 e concentrações de até 150 g.L-1 de areia. O K La aumentou ligeiramente com 30 g.L-1 e diminuiu para concentrações maiores, confirmando relatos da literatura em condições semelhantes. Um modelo para K La em meio bifásico foi ajustado para as diversas relações ensaiadas entre a área externa e a interna, postulando-se uma redução na razão entre a transferência na fase líquida e o diâmetro da bolha com o aumento da vazão de ar.

A novel HPF voltage source rectifier for variable speed refrigeration systems

A novel single-phase voltage source rectifier capable to achieve High-Power-Factor (HPF) for variable speed refrigeration system application, is proposed in this paper. The proposed system is composed by a single-phase high-power-factor boost rectifier, with two cells in interleave connection, operating in critical conduction mode, and employing a soft-switching technique, controlled by a Field Programmable Gate Array (FPGA), associated with a conventional three-phase IGBT bridge inverter (VSI - Voltage Source Inverter), controlled by a Digital Signal Processor (DSP). The soft-switching technique for the input stage is based on zero-current-switching (ZCS) cells. The rectifier's features include the reduction in the input current ripple, the reduction in the output voltage ripple, the use of low stress devices, low volume for the EMI input filter, high input power factor (PF), and low total harmonic distortion (THD) in the input current, in compliance with the EEC61000-3-2 standards. The digital controller for the output stage has been developed using a conventional voltage-frequency control (scalar V/f control), and a simplified stator oriented Vector control, in order to verify the feasibility and performance of the proposed digital controls for continuous temperature control applied at a refrigerator prototype.

Avaliação da relação entre qualidade de sono e uma intervenção com jogos para o desempenho de crianças e adolescentes

The sleep is an active brain process that allows the efficient realization of daily tasks. The changes on sleep patterns may influence the different cognitive processes performance. Many recent studies show the possibility of cognitive performance improvement, through the cognitive training with the use of computer games. The question is if these interventions may be influenced by the sleep quality. Thus, we evaluated the sleep quality effect about the efficacy of an intervention with computers games based on the working memory and attention for a cognitive performance training of elementary school students. The sample was constituted by 42 students with average age of 10,43 years old (SD=1,23), with 22 male participants and 20 female participants. We used to evaluate the sleep with the parents a sleep questionnaire, a sleep diary and the Sleep Behavior Questionnaire. In regard to intervention, the subjectives were distributed in an experimental and in a control group, both with 21 participants. In the first group occurred the intervention that consisted in the working memory and attention training with two cognitive tasks (Safari e Brain Workshop) during 30 daily minutes, for a 6 weeks period. In an equal period, the students from the control group should reproduce an artwork using drawing software. To evaluate the cognitive performance we applied before and after the intervention period the Wechsler Intelligence Scale for Children (WISC-III). The results showed that in both the groups the performance of the intelligence, working memory, attention and visuospatial skills was below of the mean. The cognitive processes evaluated after of intervention in the experimental group had a performance significantly higher in the Perceptual Reasoning Index (t = -6,24; p < 0,01) and in the Full Scale IQ (t = -5,09; p < 0,01) and Performance IQ (t = -6,52; p < 0,01), suggesting a improvement on the visuospatial skills, attention, working memory and processing speed. On the control group, the performance was significantly higher in the Coding subtest (t = -5,38; p< 0,01) and in the Perceptual Reasoning Index (t = -3,66; p = 0,01), suggesting a improvement on the visuospatial skills and attention. The mean obtained with the Sleep Behavior Questionnaire was 53,76 (SD=14,96) for an experimental group and 61,19 (SD=12,82) for a control group, indicating tendency for a bad sleep quality in that last one. Not only during the first days, but also in the last fifteen days of the intervention we verified in the two groups an adequate time to sleep, duration and regularity, in the weekdays and on the weekends. We didn t find significant differences between the two groups in none of the sleep variables. We verified statistically meaningful improvement on the performance of the experimental group with the intervention in the two games. We didn t verify significant correlations between the games performance index and in the sleep variables of the experimental group individuals. We verified significant correlations among the performance on the Brain Workshop and the Cubes subtest, the Perceptual Reasoning Index and the Scale Performance IQ, suggesting that the significant improvement of the visuospatial skills and of the attention was correlated with the performance in the Brain Workshop. Although the absence of correlations with the performance in the Safari, possibly it also has relieved in the improvement of the cognitive performance. The findings support the hypothesis that the computer games might be a satisfactory tool for the improvement of the performance in visuospatial skills and attention. This can be resulted of the insertion of visuospatial stimulations in the task, for example, graphical elements with thematic for children that increase the interest. The IQ below mean the individuals might have influenced the improvement absence on the cognitive processes like the working memory with games. Moreover, it wasn t verified a relation between the sleep quality and the intervention efficacy. It might have been influenced by the n of the sample. Future studies must focalize in the improvement of the effect of the interventions with games

Controlled release system for ametryn using polymer microspheres: Preparation, characterization and release kinetics in water

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Produtividade e qualidade de abacaxizeiro cv. Smooth Cayenne, cultivado comaplicação de doses e parcelamentos do nitrogênio, em Guaraçaí-SP

A adubação é um dos fatores que influem na produção e qualidade dos frutos; portanto, a necessidade de se estudar o efeito do nitrogênio aplicado antes e após a indução floral nestas características dos frutos de abacaxi é fundamental. Os objetivos deste trabalho foram avaliar a produtividade, o estado nutricional e os aspectos quantitativos e qualitativos dos frutos de abacaxizeiro 'Smooth Cayenne' submetidos a doses e parcelamentos do nitrogênio, cultivado em Guaraçaí-SP. O delineamento experimental adotado foi o de blocos ao caso, com quatro repetições e dezesseis tratamentos, num esquema fatorial 4x4, sendo quatro doses de N: 7,5; 15; 22,5 e 30 g planta-1 de N, e quatro parcelamentos: toda a dose aplicada antes da indução floral, metade da dose antes da indução floral e a outra metade após a indução, 2/3 da dose antes da indução e 1/3 da dose após a indução e toda a dose após a indução floral. A aplicação total do N após a indução floral, independentemente da dose, resultou em menores teores foliares de N e dimensões da folha D, apresentando na colheita frutos pequenos, com menor índice de maturação e maior acidez. Para obtenção de frutos de abacaxi cv. Smooth Cayenne, com maior tamanho, massa e maior teor de SST e menor acidez, a adubação nitrogenada pode ser aplicada em dose total, antes da indução floral, ou parcelada 2/3 antes e 1/3 após esta indução. A adubação nitrogenada incrementou os teores foliares de N, entretanto não teve efeito nas dimensões, produtividade e qualidade de frutos de abacaxizeiro cv. Smooth Cayenne.

Tontura em idosos institucionalizados da cidade do NATAL/RN: Um estudo caso-controle em vestibulopatas e não-vestibulopatas

the institutionalized elderly presents for being more fragile a lot of body balance s changes, which can induce falls and health frailty. One of the consequences of it is the appearance of dizziness, vestibular or not. This study aims to identify the risk factors related to dizziness in institutionalized elderly, with and without vestibular disorders, in the city of Natal-RN. Method: a case-control study realized in 12 regulated by Health Surveillance Long Term Care Institutions for the elderly in Natal-RN. Elected seniors with good cognitive level and able to walk, totaling 115 individuals, and of these, 102 were selected according to the presence of dizziness in the last year (n = 51) and their controls (n = 51), paired by sex and age. The 51 elderly patients with dizziness were divided into 3 groups case: case one, for elderly with dizziness and without vestibulopathy (n=38); case two, for elderly with dizziness and vestibulopathy (n=13) and case three, for all the seniors with dizziness, or added to the case 1 case 2 (n=51). The 51 seniors who served as controls were also divided into three groups, according to the number of individuals of each case: control 1, n = 38, control 2, n = 13 control and 3 (sum of 1 control with control 2), n = 51. As possible risk factors were analyzed variables related to characteristics of the institution, to the habits of life of older people and those concerned with the health of the elderly. For statistical analysis, we used the chi-square or Fisher exact test for a significance level of 5% and calculating the association magnitude between variables by measuring the Odds Ratio. Results: as risk factors for dizziness without vestibular disorders were found the presence of hypertension and cardiovascular disease, as well as the presence of three or more disorders for elderly and use of gastric protector drugs. For the elderly group from case two were found no associated risk factor. For elderly patients with dizziness in the case group three, we observed the same risk factors found for the elderly in the case group one, plus the presence of osteoarthritis pathology, which was also significant for this group. Conclusion: dizziness in institutionalized elderly is associated with systemic common diseases in this age group and the vestibulopathy presents itself as pathology on an isolated way, not being possible, with our data, associate it with non-risk factors