Estudo experimental do movimento de partículas carregadas em campos elétricos e magnéticos: seletor de velocidades

Neste trabalho é apresentado um experimento incluído no contexto de experimentos longos adotado nas disciplinas experimentais de eletricidade, magnetismo e óptica, e consiste na caracterização de um seletor de velocidades que funciona com campos elétricos e magnéticos cruzados. Utiliza-se um tubo de raios catódicos para gerar um feixe de elétrons. As placas de deflexão vertical do tubo geram o campo elétrico e um par de bobinas, com os eixos perpendiculares ao eixo do tubo, gera o campo magnético. São realizados estudos de trajetória dos elétrons com auxílio de um programa de simulação de elétrons.

The optical analysis of the abdominal wall using the biospeckle after implants of polypropylene mesh in rats

PURPOSE: To evaluate an experimental animal model to study the abdominal tissue activity considering its interaction with a polypropylene mesh, through the use of one of the optical phenomena of light Laser, the biospeckle. METHODS: Fifty Wistar male rats were divided into four groups: Group 1: ten animals not submitted to surgery; Group 2: ten animals submitted to surgery without polypropylene mesh; Group 3: 20 animals submitted to surgery followed by the mesh placement; Group 4: (sham) with ten animals. None of the animals presented post surgical complications being submitted to the optical tests at the 20th postoperative day. RESULTS: The analysis from the biospeckle tests, comparing the medians and standard deviations with T Student test, indicated that no significative difference was observed on the abdominal wall tissue activity in the four groups considered, with and without polypropylene mesh prosthesis implantation. CONCLUSION: The animal model is viable and the biospeckle open ways for a great number of experiments to be developed in evaluating tissue activity.

Steviol effect, a glycoside of Stevia rebaudiana, on glucose clearances in rats

Stevia rebaudiana, a South American plant normally used as a natural herbal sweetener, has been suggested as exerting beneficial effects on human health, including as an antihypertensive and antihyperglycemic. The present experiment was undertaken to evaluate the renal excretion of steviol, the aglycone of several natural products extracted from the leaves of S. rebaudiana, and to clarify the actual participation of this compound on the renal excretion of glucose in rats, which has been previously suggested as the preferential action of steviol on the Na+-glucose renal tubular transport system. Steviol was obtained by enzymatic hydrolysis of stevioside with pectinase. Thirty normal male Wistar rats weighing 345 g were used. After a control period, steviol was infused iv at three doses (0.5, 1.0 and 3.0 mg.kg-1/h), according to classical clearance techniques. During all the experiments no significant changes in inulin clearance (Cin) and p-aminohipuric acid clearance (C PAH) were observed. Administration of steviol resulted in a statistically significant increase in the fractional sodium excretion (FeNa+), fractional potassium excretion (FeK+), urinary flow as percent of glomerular filtration rate (V/GFR) and glucose clearance (C G) when compared to controls, but these effects were absent with the dose of 0.5 mg.kg-1/h. The steviol clearance (C S) was higher than the Cin and lower than the C PAH at all the doses employed in this study. The data suggest that steviol is secreted by renal tubular epithelium, causing diuresis, natriuresis, kaliuresis and a fall in renal tubular reabsorption of glucose.

Determination and fractionation of barium in Brazil nuts

Several sample preparation strategies were employed for determination and fractionation of barium in Brazil nuts using measurements by graphite furnace atomic absorption spectrometry (GF AAS) and inductively coupled plasma optical emission spectrometry with axial view (ICP OES). This food is widely consumed because of its nutritional value and good taste. The chemical analysis of Brazil nuts is not trivial due to their complex matrix. The fractionation of barium in Brazil nuts was studied owing to the toxicity of this element and the strong correlation between chemical form and absorption. Total concentrations of barium varied from 860 to 2084 mg kg-1. Sequential extractions were performed based on solubility in different media and also according to lipids, proteins and low molecular weight fractions (LMW). The greatest contents of barium were determined in the LMW and in the water insoluble fractions with concentrations in the range 778 to 1606 and 551 to 1520 mg kg-1, respectively. Based on these results it can be inferred that Ba is not absorbed when Brazil nuts are ingested. Considering both the contents of barium and sulfur in different fractions and stoichiometric calculations it was also possible to assume that barium occurs mainly in the BaSO4 form. The presence of this chemical form was also confirmed by thermogravimetric measurements.

Production of DNA microarray and expression analysis of genes from Xylella fastidiosa in different culture media

DNA Microarray was developed to monitor the expression of many genes from Xylella fastidiosa, allowing the side by-side comparison of two situations in a single experiment. The experiments were performed using X. fastidiosa cells grown in two culture media: BCYE and XDM2. The primers were synthesized, spotted onto glass slides and the array was hybridized against fluorescently labeled cDNAs. The emitted signals were quantified, normalized and the data were statistically analyzed to verify the differentially expressed genes. According to the data, 104 genes were differentially expressed in XDM2 and 30 genes in BCYE media. The present study showed that DNA microarray technique efficiently differentiate the expressed genes under different conditions.

Non-coding RNAs in schistosomes: an unexplored world

Non-coding RNAs (ncRNAs) were recently given much higher attention due to technical advances in sequencing which expanded the characterization of transcriptomes in different organisms. ncRNAs have different lengths (22 nt to >1, 000 nt) and mechanisms of action that essentially comprise a sophisticated gene expression regulation network. Recent publication of schistosome genomes and transcriptomes has increased the description and characterization of a large number of parasite genes. Here we review the number of predicted genes and the coverage of genomic bases in face of the public ESTs dataset available, including a critical appraisal of the evidence and characterization of ncRNAs in schistosomes. We show expression data for ncRNAs in Schistosoma mansoni. We analyze three different microarray experiment datasets: (1) adult worms' large-scale expression measurements; (2) differentially expressed S. mansoni genes regulated by a human cytokine (TNF-α) in a parasite culture; and (3) a stage-specific expression of ncRNAs. All these data point to ncRNAs involved in different biological processes and physiological responses that suggest functionality of these new players in the parasite's biology. Exploring this world is a challenge for the scientists under a new molecular perspective of host-parasite interactions and parasite development.

Oxidative DNA damage induced by S(IV) in the presence of Cu(II) and Cu(I) complexes

The DNA damage induced by S(IV) in the presence of some Cu(II) complexes in air saturated solution was investigated. The addition of S(IV) to an air saturated solution containing CuII GGA (GGA = glycylglycyl-L-alanine), CuII G3 (G3 = triglycine) or CuII G4 (G4 = tetraglycine) and Ni(II) traces, causes rapid formation of the respective Cu(III) complex, with simultaneous O2 uptake and S(IV) oxidation. SO3•- and HO• were detected by EPR-spin trapping experiments. The DNA strand breaks were attributed to the oxysulfur radicals formed. In the reduction of Cu(II)/BCA (BCA = 4,4' dicarboxy-2-2'-biquinoline) by S(IV), with CuI BCA complex formation, there is the possible formation of carbon centered radical of BCA or peroxyl radical (ROO•) capable of oxidizing DNA bases. The intensity of DNA damage in the presence of these Cu(II) complexes and S(IV) (10-300 µmol L-1) followed the order: CuII BCA ∼ CuII G4 ∼ Cu(II) (added as Cu(NO3)2) > CuII G3 ∼ CuII GGA. Specifically for CuII BCA the damage occurred even at lower S(IV) concentration (0.1 µmol L-1). For the Cu(II) complexes with glycylglycylhistidine, glycylhistidylglycine, glycylhistidyllysine and glycylglycyltyrosylarginine the Cu(III) formation and the DNA damage was not observed.

Thermal behavior and decomposition kinetics of rifampicin polymorphs under isothermal and non-isothermal conditions

The thermal behavior of two polymorphic forms of rifampicin was studied by DSC and TG/DTG. The thermoanalytical results clearly showed the differences between the two crystalline forms. Polymorph I was the most thermally stable form, the DSC curve showed no fusion for this species and the thermal decomposition process occurred around 245 ºC. The DSC curve of polymorph II showed two consecutive events, an endothermic event (Tpeak = 193.9 ºC) and one exothermic event (Tpeak = 209.4 ºC), due to a melting process followed by recrystallization, which was attributed to the conversion of form II to form I. Isothermal and non-isothermal thermogravimetric methods were used to determine the kinetic parameters of the thermal decomposition process. For non-isothermal experiments, the activation energy (Ea) was derived from the plot of Log β vs 1/T, yielding values for polymorph form I and II of 154 and 123 kJ mol-1, respectively. In the isothermal experiments, the Ea was obtained from the plot of lnt vs 1/T at a constant conversion level. The mean values found for form I and form II were 137 and 144 kJ mol-1, respectively.

Circulation and suspended particulate matter transport in a tidally dominated estuary: caravelas estuary, Bahia, Brazil

The circulation and transport of suspended particulate matter in the Caravelas Estuary are assessed. Nearly-synoptic hourly hydrographic, current (ADCP velocity and volume transport) and suspended particulate matter data were collected during a full semidiurnal spring tide, on the two transects Boca do Tomba and Barra Velha and on longitudinal sections at low and high tide. On the first transect the peak ebb currents (-1.5 ms-1) were almost twice as strong as those of the wider and shallow Barra Velha inlet (-0.80 ms-1) and the peak flood currents were 0.75 and 0.60 ms-1, respectively. Due to the strong tidal currents both inlets had weak vertical salinity stratification and were classified with the Stratification-circulation Diagram as Type 2a (partially mixed-weakly stratified) and Type 1a (well mixed). Volume transports were very close, ranging from -3,500 to 3,100 m³s-1 at the ebb and flood, respectively, with a residual -630 m³s-1. The concentration of the suspended particulate matter was closely related to the tidal variation and decreased landwards from 50 mg.L-1 at the estuary mouth, to 10 mg.L-1 at distances of 9 and 16 km for the low and high tide experiments, respectively. The total residual SPM transport was out of the estuary at rates of -18 tons per tidal cycle.

Efeito da fotoperiodicidade na taxa de prenhez em ratos isogênicos (F344)

O uso de animais isogênicos apresenta grandes vantagens experimentais, como uniformidade fenotípica e genotípica (reduzindo o número de animais em experimentos) e histocompatibilidade, permitindo, assim, o acúmulo de informações e a repetibilidade dos experimentos. A linhagem isogênica de Rattus norvegicus Fischer 344 existe há 90 anos, entretanto pouco se sabe sobre as razões de seu baixo índice reprodutivo. O presente estudo demonstrou que ratos Fischer F344 são fotorresponsivos quanto à reprodução, tendo seus índices de prenhezes acrescidos com o aumento do fotoperíodo. Os melhores índices são obtidos quando os machos são submetidos a 14 horas de luz e fêmeas a 16 horas de luz, indicando dimorfismo sexual na fotorresponsividade.

Fontes orgânicas e inorgânicas de zinco e cobre como melhoradores de desempenho em leitões desmamados

Foram conduzidos dois experimentos para avaliar fontes orgânicas e inorgânicas de zinco e cobre nas dietas e seus efeitos no desempenho de leitões desmamados aos 21 dias de idade. Em cada experimento, foram utilizados 90 leitões em delineamento experimental de blocos ao acaso, com cinco dietas, seis repetições e três animais por parcela. As dietas utilizadas nos experimentos 1 e 2 continham 120 ppm de zinco e 10 ppm de cobre na forma de sulfato. No experimento 1, foram suplementadas com 0, 300, 600 e 900 ppm de zinco na forma orgânica ou 2.400 ppm na forma de óxido (ZnO) e, no experimento 2, com 0, 50, 100 e 150 ppm de cobre na forma orgânica ou 240 ppm de cobre na forma de sulfato (CuSO4 H2O). No experimento 1, os níveis de zinco de fonte orgânica tiveram efeito linear no consumo de ração e no ganho de peso nos períodos de 0 a 15 dias e de 0 a 21 dias pós-desmame. O ganho de peso nas fases de 0 a 35 dias e de 0 a 42 dias pós-desmame e o consumo de ração dos leitões que receberam a dieta com 900 ppm de zinco de fonte orgânica não diferiram dos valores observados naqueles que receberam a dieta com 2.400 ppm de zinco na forma inorgânica. A suplementação da dieta com zinco na forma orgânica (900 ppm) ou inorgânica (2.400 ppm) aumentou o consumo de ração e o ganho de peso de leitões nas primeiras três semanas após o desmame. A suplementação da dieta com 2.400 ppm de zinco na forma inorgânica reduziu a incidência de diarreia nas primeiras três semanas pós-desmame. No experimento 2, os níveis de cobre de fonte orgânica tiveram efeito quadrático no consumo de ração dos leitões nos períodos de 0 a 31 e de 0 a 40 dias pós-desmame. A suplementação da dieta com cobre, tanto de fonte orgânica (90 ppm) como inorgânica (240 ppm), aumenta o consumo de ração e o ganho de peso de leitões nos primeiros 40 dias pós-desmame.

Formulação de rações para leitões com base nos nutrientes digestíveis da silagem de grãos úmidos de milho

O estudo foi realizado com o objetivo de avaliar o resultado econômico e o desempenho de leitões na fase de creche alimentados com rações formuladas com base nos nutrientes digestíveis da silagem de grãos úmidos de milho. Foram utilizados 18 leitões mestiços (Landrace × Large White) com peso médio inicial de 16,01 kg no experimento de digestibilidade e 60 leitões mestiços com peso médio inicial de 7,11 kg no experimento de desempenho. O delineamento experimental nos dois experimentos foi em blocos ao acaso. No experimento de digestibilidade, avaliou-se uma ração-referência contendo ou não 30% de milho seco moído (30%) e silagem de grãos úmidos de milho e, no experimento de desempenho, avaliaram-se quatro rações: à base de grãos de milho seco moídos; à base de silagem de grãos úmidos de milho (SGUM) em substituição a 100% do milho seco, com base na matéria seca; à base de SGUM, considerando o valor de energia digestível da silagem determinado no experimento de digestibilidade; e à base de SGUM, considerando os valores de energia digestível, proteína digestível e fósforo disponível da silagem, determinados no experimento de digestibilidade. A digestibilidade aparente de matéria seca (MS), proteína bruta (PB), fósforo (P) e cálcio (Ca) e o nível de energia digestível foram maiores para a ração à base de SGUM formulada considerando os valores nutricionais determinados no experimento de digestibilidade. Durante o período total do experimento de desempenho (0 a 32 dias), a SGUM proporcionou melhor conversão alimentar e os menores custos/kg de peso ganho, mas não foram observadas diferenças no ganho diário de peso e no consumo diário de ração. Na formulação de rações com silagem de grãos úmidos de milho para suínos, deve-se considerar o valor nutricional, principalmente o teor de energia digestível, desse alimento.

Transport-Regional Equity Issue Revisited

Almeida E. S. de, Haddad E. A. and Hewings G. J. D. Transport-regional equity issue revisited, Regional Studies. The objective of this paper is to analyse the relationship between transport and regional equity in Minas Gerais, Brazil. Furthermore, the existence of a trade-off between economic performance and regional equity is investigated as well. To do so, the paper develops a spatial computable general equilibrium model based on Brocker and Schneider`s approach of 2002 to implement comparative static analysis, explicitly incorporating iceberg transportation costs. Four activities are modelled, namely production, final demand, transportation and exports. Two production factors are assumed: labour and other factors. The model has 12 domestic regions and three external regions. Four counterfactual experiments are developed based on decreases in transportation costs due to a `distance shortening`. The main findings indicate that if the transport infrastructure improvement is focused only among poor regions, the promotion of regional equity is insignificant. If the transport infrastructure improvement links are concentrated among rich regions, there is an increase in regional income inequalities. However, if the improvements are targeted to the roads linking poor regions and rich ones, there is greater promotion of regional equity. The same result will occur when improvements are made to all road links of the state. [image omitted] Almeida E. S. de, Haddad E. A. et Hewings G. J. D. La question du rapport entre le transport et l`equilibre regional vue sous un jour nouveau, Regional Studies. Cet article cherche a analyser le rapport entre le transport et l`equilibre regional en Minas Gerais au Bresil. En outre, on examine la presence d`un echange entre la performance economoique et l`equilibre regional. Pour le faire, on construit un modele geographique de l`equilibre general a utiliser sur ordinateur fonde sur l`approche de Brockner et Schneider en 2002 afin de mettre en oeuvre une analyse statique comparative qui comprend explicitement les frais de transport iceberg. On modelise quatre activites, a savoir, la production, la demande finale, le transport et l`exportation. On fait deux suppositions quant aux facteurs de production: la main-d`oevre et d`autres facteurs. Le modele embrasse douze regions internes et trois regions externes. On fait quatre experiences paradoxales fondees sur la baisse des frais de transport due a une `reduction des distances`. Les principaux resultats indiquent que si l`amelioration de l`equipement de transport ne porte que sur les regions defavorisees, la promotion de l`equilibre regional s`avere negligeable. Si l`amelioration de l`equipement de transport focalise les regions riches, il s`avere un creusement des ecarts des revenus regionaux. Cependant, si les ameliorations ciblent les routes qui relient les regions defavorisees aux regions riches, il s`avere une plus grande promotion de l`equilibre regional. Il en va de meme pour la situation ou on a apporte des amenagements a toutes les liaisons routieres de l`etat. Modele geographique de l`equilibre general a utiliser sur ordinateur Equilibre regional Peformance economique Frais de transport Almeida E. S. de, Haddad E. A. und Hewings G. J. D. Die Wiederaufnahme der Frage von Verkehrswesen im Verhaltnis zu regionaler Fairness, Regional Studies. Dieser Aufsatz beabsichtigt, die Beziehung zwischen Verkehrswesen und regionaler Fairness in Minas Gerais (Brasilien) zu analysieren und zugleich auch das Vorkommen von Einbussen entweder bei wirtschaftlicher Leistung der regionaler Fairness zu untersuchen. Zu diesem Zwecke wird ein auf dem Ansatz von Brocker und Schneider (2002) aufbauendes raumliches komputables allgemeines Gleichgewichtsmodell entwickelt, um vergleichende statistische Analysen durchzufuhren, wobei verborgene `Eisberg`-Transportkosten ausdrucklich berucksichtigt werden. Es werden vier Unternehmenstatigk eiten aufgefuhrt: Herstellung, Nachfrage, Transportwesen und Exporte, und zwei Produktionsfaktoren vorausgesetzt: Arbeitskrafte und andere Faktoren. Das Modell umfasst zwolf Inlandsregionen und drei externe Regionen. Es werden vier gegensatzliche Experimente entwickelt, die auf einer Abnahme der Transportkosten infolge einer `Verkurzung der Entfernungen` beruhen. Die Hauptbefunde weisen darauf hin, dass die Forderung regionaler Fairness unbedeutend bleibt, wenn die Verbesserungen der Transportinfrastruktur sich nur auf minderbemittelte Regionen konzentrieren; werden die Verbesserungen der Verbindungen der Transportinfrastruktur in wohlhabenden Regionen durchgefuhrt, so nehmen regionale Einkommensunterschiede zu. Wenn die Verbesserungen jedoch auf Strassen abzielen, die wohlhabende Regionen mit weniger bemittelten verbinden, wird regionale Fairness starker gefordert. Das gleiche Ergebnis wird sich einstellen, wenn Verbesserungen an allen Strassenverbindungen des Staates vorgenommen werden. Raumliches, komputables, allgemeines Gleichgewichtsmodell Regionale Fairness Wirtschaftsleistung Transportkosten Almeida E. S. de, Haddad E. A. y Hewings G. J. D. Revisando el tema de la igualdad del transporte en las regiones, Regional Studies. El objetivo de este documento es analizar la relacion entre el transporte y la igualdad regional en Minas Gerais, Brasil. Asimismo investigamos la existencia de una compensacion entre el rendimiento economico y la igualdad regional. Para ello desarrollamos un modelo de equilibrio general computable y espacial basado en el enfoque de Brocker y Schneider en 2002 para hacer un analisis estatico y comparativo, explicitamente incorporando los costes ocultos de transporte. Se modelan cuatro actividades: la produccion, la demanda final, el transporte y las exportaciones. Suponemos que existen dos factores de produccion: mano de obra y otros factores. En este modelo, existen doce regiones internas y tres regiones externas. Desarrollamos cuatro experimentos contrafactuales basados en la disminucion de los costes de transporte debido a una `acortamiento de las distancias`. Los principales resultados indican que si la mejora de la infraestructura del transporte se centra solo entre las regiones mas pobres, el fomento de la igualdad regional es insignificante. Si los enlaces de la mejora de la infraestructura del transporte se concentran en las regiones ricas, aumentan las desigualdades de ingresos regionales. Sin embargo, si se mejoran los enlaces de carreteras entre las regiones pobres y ricas, se fomenta mejor la igualdad regional. El mismo resultado ocurre cuando se mejoran los enlaces de todas las carreteras del estado. Modelo de equilibrio general computable y espacial Igualdad regional Rendimiento economico Costes de transporte.