Caracterização bioquímica de isolados de rizóbio obtidos de nódulos de Crotalaria juncea L.

O objetivo desse estudo foi determinar as características bioquímicas de bactérias obtidas a partir de nódulos de Crotalaria juncea.Pôster - pós-graduação

Morphological transition between diffusion-limited and ballistic aggregation growth patterns

In this work, the transition between diffusion-limited and ballistic aggregation models was revisited using a model in which biased random walks simulate the particle trajectories. The bias is controlled by a parameter $\lambda$, which assumes the value $\lambda=0$ (1) for ballistic (diffusion-limited) aggregation model. Patterns growing from a single seed were considered. In order to simulate large clusters, a new efficient algorithm was developed. For $\lambda \ne 0$, the patterns are fractal on the small length scales, but homogeneous on the large ones. We evaluated the mean density of particles $\bar{\rho}$ in the region defined by a circle of radius $r$ centered at the initial seed. As a function of $r$, $\bar{\rho}$ reaches the asymptotic value $\rho_0(\lambda)$ following a power law $\bar{\rho}=\rho_0+Ar^{-\gamma}$ with a universal exponent $\gamma=0.46(2)$, independent of $\lambda$. The asymptotic value has the behavior $\rho_0\sim|1-\lambda|^\beta$, where $\beta= 0.26(1)$. The characteristic crossover length that determines the transition from DLA- to BA-like scaling regimes is given by $\xi\sim|1-\lambda|^{-\nu}$, where $\nu=0.61(1)$, while the cluster mass at the crossover follows a power law $M_\xi\sim|1 -\lambda|^{-\alpha}$, where $\alpha=0.97(2)$. We deduce the scaling relations \beta=\n u\gamma and $\beta=2\nu-\alpha$ between these exponents.Comment: 7 pages, 8 figure

Aluminium-Based Dissimilar Alloys Surface Composites Reinforced with Functional Microparticles Produced by Upward Friction Stir Processing

Funding Information: T.G.S. and C.V. acknowledge Fundação para a Ciência e a Tecnologia (FCT-MCTES) for its financial support via projects UIDB/00667/2020 and UIDP/00667/2020 (UNIDEMI). P.M.F. also acknowledges FCT-MCTES for its financial support via the PhD scholarship UI/BD/151055/2021. R.J.C.S. acknowledges national funds from FCT-MCTES in the scope of the project UIDB/50025/2020–2023 of the CENIMAT/i3N. Publisher Copyright: © 2023 by the authors.Surface metal matrix composites offer an excellent solution for applications where surface properties play a crucial role in components’ performance and durability, such as greater corrosion resistance, better wear resistance, and high formability. Solid-state processing techniques, such as friction surfacing and friction stir welding/processing, offer several advantages over conventional liquid-phase processing methods. This research investigated the feasibility of producing surface composites of aluminium-based dissimilar alloys reinforced with functional microparticles through experimental validation, determined the process parameters that resulted in a more homogeneous distribution of the particles in the surface composites, and enhanced the understanding of Upward Friction Stir Processing (UFSP) technology. The production of aluminium-based dissimilar alloys (AA 7075-T651 and AA 6082-T651) surface composites reinforced with SiC particles was studied, and it was concluded that the macrography and micrography analyses, scanning electron microscopy (SEM) analysis, microhardness measurements, and eddy currents technique reveal an extensive and homogeneous incorporation of SiC particles. In the stirred zone, a decrease of approximately 20 HV 0.5 in hardness was observed compared to the base material. This reduction is attributed to the weakening effect caused by low-temperature annealing during UFSP, which reduces the strengthening effect of the T651 heat treatment. Additionally, the presence of particles did not affect the surface composite hardness in the stirred zone. Furthermore, despite the presence of significant internal defects, SEM analyses revealed evidence of the lower alloy merging with the upper zone, indicating that the lower plate had a role beyond being merely sacrificial. Therefore, the production of bimetallic composites through UFSP may offer advantages over composites produced from a monometallic matrix. The results of the eddy currents testing and microhardness measurements support this finding and are consistent with the SEM/EDS analyses.publishersversionpublishe

Caracterização da vegetação de caatinga e da dieta de novilhos no Sertão de Pernambuco.

O objetivo deste trabalho foi avaliar a composição botânica, a disponibilidade e a qualidade da forragem e da dieta de animais fistulados alimentados na caatinga, no período chuvoso, em Pernambuco. Avaliaram-se a composição botânica e a disponibilidade de fitomassa dos estratos herbáceo, arbustivo e arbóreo, nos meses de março e junho. A avaliação da qualidade da forragem foi feita por meio da análise bromatológica, realizada em todos os meses do período chuvoso. Foram encontradas 67 espécies, das quais 28 herbáceas, 20 arbustivas e 19 arbóreas. Destas, 19 foram encontradas na dieta dos animais. A disponibilidade de fitomassa do componente herbáceo variou de 1.369 kg ha-¹ de matéria seca (MS), em março, para 452 kg ha-¹ de MS em junho. A disponibilidade do estrato arbustivo aproximou-se do herbáceo enquanto o componente arbóreo contribuiu com apenas 178 kg ha-¹ de MS. Apesar de a disponibilidade de fitomassa ser relativamente alta, apenas uma pequena porcentagem do material encontrado pode ser considerada como forragem. Foi observada baixa digestibilidade da proteína, provavelmente em conseqüência do alto teor em lignina

Caracterização morfológica de germoplasma de inhame.

O cultivo do inhame (Discorea sp.) vem crescendo nos últimos anos e ganhando produções expressivas no Brasil e no mundo. No cenário mundial, a Nigéria está em primeiro lugar, com a produção em 2010, de 29 milhões de toneladas. A produção e área plantada no Brasil em 2010 foram de aproximadamente 232 mil toneladas e 25 mil hectares, respectivamente (FAOSTAT, 2012). A cultura concentra-se principalmente na Região Nordeste. Embora o inhame represente a fonte de renda de várias famílias brasileiras, pouco se conhece a respeito da variabilidade genética nessa cultura. Portanto, o objetivo do trabalho foi avaliar a diversidade genética de 39 acessos de inhame pertencentes ao germoplasma da UFRB por meio de características morfológicas. A análise da diversidade utilizando características qualitativas evidenciou variabilidade entre os acessos avaliados, com distâncias genética que variaram de 0 a 4.22%. Essas informações servirão de base para auxiliar as estratégias de melhoramento genético da espécie; que visa à obtenção de variedades de inhame mais produtivas e resistentes aos principais fatores bióticos e abióticos

Avaliação de atributos físicos do solo da área de plantio de barragens subterrâneas.

Um dos aspectos técnicos fundamentais na condução de barragens subterrâneas é o monitoramento dos atributos do solo da área de plantio. Entre esses a avaliação das características físicas do solo é determinante pela sua contribuição na definição do uso e manejo dessas áreas. Diante do exposto, o presente trabalho teve como objetivo a avaliação da qualidade física dos solos das áreas de plantio de duas barragens subterrâneas (BS1 e BS2) localizadas no Semiárido do Estado da Paraíba. A amostragem foi realizada em março de 2009, no início do período chuvoso. As amostras foram coletadas em zigue-zague, em sete pontos de cada área, em três profundidades, 0-10 cm, 10-20 cm e 20-40 cm, em cada barragem subterrânea. Foram determinados: a composição granulométrica pelo método da pipeta; densidade do solo (DS) pela proveta; a densidade das partículas (DP) pelo método do balão volumétrico de 50 mL; a partir da Ds e Dp foi calculada a porosidade total (PTotal). De uma maneira geral, a BS1 apresentou melhores condições físicas para o desenvolvimento das culturas, com maiores teores de argilosa, DS menores, PTotal maiores, consequentemente melhores condições para o uso e manejo de suas áreas, consequentemente obtenção de melhores produções do que a BS2

Gold nanoparticles functionalised with stable, fast water exchanging Gd3+ chelates as high relaxivity contrast agents for MRI

Gold nanoparticles functionalized with Gd3+ chelates displaying fast water exchange, superb pH stability and inertness towards transmetalation with Zn2+ have been prepared and characterized as a new high relaxivity (29 mM-1s-1, 30 MHz, 25 ºC) Contrast Agent potentially safe for in vivo MRI applications. The Lipari-Szabo treatment for internal rotation was used to evaluate the effect of linker flexibility on the relaxivity of the gold nanoparticles. The relaxivity is limited by chelate flexibility. The effect of fast water exchange on the relaxivity of gold nanoparticles functionalized with Gd3+ chelates is also addressed in this communication.Fundação para a Ciência e TecnologiaProjecto PTDC/QUI/70063/2006PhD grant SFRH/BD/63994/2008 to Miguel FerreiraRede Nacional de RMN REDE/1517/RMN/2005 for the acquisition of the Varian VNMRS 600 NMR spectrometer in Coimbra and the Bruker Avance-3 400 Plus in BragaB. Mousavi and L. Helm acknowledge financial support by the Swiss National Science Foundation.COST D38 Actio

Mechanisms Underlying Gas Exchange Alterations In An Experimental Model Of Pulmonary Embolism.

The aim of the present study was to determine the ventilation/perfusion ratio that contributes to hypoxemia in pulmonary embolism by analyzing blood gases and volumetric capnography in a model of experimental acute pulmonary embolism. Pulmonary embolization with autologous blood clots was induced in seven pigs weighing 24.00 +/- 0.6 kg, anesthetized and mechanically ventilated. Significant changes occurred from baseline to 20 min after embolization, such as reduction in oxygen partial pressures in arterial blood (from 87.71 +/- 8.64 to 39.14 +/- 6.77 mmHg) and alveolar air (from 92.97 +/- 2.14 to 63.91 +/- 8.27 mmHg). The effective alveolar ventilation exhibited a significant reduction (from 199.62 +/- 42.01 to 84.34 +/- 44.13) consistent with the fall in alveolar gas volume that effectively participated in gas exchange. The relation between the alveolar ventilation that effectively participated in gas exchange and cardiac output (V Aeff/Q ratio) also presented a significant reduction after embolization (from 0.96 +/- 0.34 to 0.33 +/- 0.17 fraction). The carbon dioxide partial pressure increased significantly in arterial blood (from 37.51 +/- 1.71 to 60.76 +/- 6.62 mmHg), but decreased significantly in exhaled air at the end of the respiratory cycle (from 35.57 +/- 1.22 to 23.15 +/- 8.24 mmHg). Exhaled air at the end of the respiratory cycle returned to baseline values 40 min after embolism. The arterial to alveolar carbon dioxide gradient increased significantly (from 1.94 +/- 1.36 to 37.61 +/- 12.79 mmHg), as also did the calculated alveolar (from 56.38 +/- 22.47 to 178.09 +/- 37.46 mL) and physiological (from 0.37 +/- 0.05 to 0.75 +/- 0.10 fraction) dead spaces. Based on our data, we conclude that the severe arterial hypoxemia observed in this experimental model may be attributed to the reduction of the V Aeff/Q ratio. We were also able to demonstrate that V Aeff/Q progressively improves after embolization, a fact attributed to the alveolar ventilation redistribution induced by hypocapnic bronchoconstriction.391197-20

The Effect of Long-Chain Polyunsaturated Fatty Acids Intake During Pregnancy on Adiposity of Healthy Full-Term Offspring at Birth

OBJECTIVE: The adjusted effect of long-chain polyunsaturated fatty acid (LCPUFA) intake during pregnancy on adiposity at birth of healthy full-term appropriate-for-gestational age neonates was evaluated. STUDY DESIGN: In a cross-sectional convenience sample of 100 mother and infant dyads, LCPUFA intake during pregnancy was assessed by food frequency questionnaire with nutrient intake calculated using Food Processor Plus. Linear regression models for neonatal body composition measurements, assessed by air displacement plethysmography and anthropometry, were adjusted for maternal LCPUFA intakes, energy and macronutrient intakes, prepregnancy body mass index and gestational weight gain. RESULT: Positive associations between maternal docosahexaenoic acid intake and ponderal index in male offspring (β=0.165; 95% confidence interval (CI): 0.031-0.299; P=0.017), and between n-6:n-3 LCPUFA ratio intake and fat mass (β=0.021; 95% CI: 0.002-0.041; P=0.034) and percentage of fat mass (β=0.636; 95% CI: 0.125-1.147; P=0.016) in female offspring were found. CONCLUSION: Using a reliable validated method to assess body composition, adjusted positive associations between maternal docosahexaenoic acid intake and birth size in male offspring and between n-6:n-3 LCPUFA ratio intake and adiposity in female offspring were found, suggesting that maternal LCPUFA intake strongly influences fetal body composition