Advances in Natural Fiber Cement Composites: A Material for the Sustainable Construction Industry

The need for economical, sustainable, safe, and secure shelter is an inherent global problem and numerous challenges remain in order to produce environmentally friendly construction products which are structurally safe and durable. The use of sisal, a natural fiber with enhanced mechanical performance, as reinforcement in a cement based matrix has shown to be a promising opportunity. This work addresses the development and advances of strain hardening cement composites using sisal fiber as reinforcement. Sisal fibers were used as a fabric to reinforce a multi-layer cementitious composite with a low content of Portland cement. Monotonic direct tensile tests were performed in the composites. The crack spacing during tension was measured by image analysis and correlated to strain. Local and global deformation was addressed. To demonstrate the high performance of the developed composite in long term applications, its resistance to tensile fatigue cycles was investigated. The composites were subjected to tensile fatigue load with maximum stresses ranging from 4 to 9.6 MPa at a frequency of 2 Hz. The composites did not fatigue below a maximum fatigue level of 6 MPa up to 106 cycles. Monotonic tensile testing was performed for composites that survived 106 cycles to determine its residual strength

Functional expression of Yarrowia lipolytica acetyl- CoA carboxylase in Saccharomyces cerevisiae

Malonyl coenzyme A (Malonyl-CoA) is an important precursor for a range of economically valuable compounds such as biodiesel, 3-hydroxypropionic acid, fatty alcohols, flavonoids, stilbenoids and polyketides. Even though Saccharomyces cerevisiae is one of the most used cell factories for the production of a variety of compounds, it is limited in its ability to generate malonyl-CoA and derived products. In this yeast, the only source of malonyl-CoA is the ATP-dependent carboxylation of acetyl coenzyme A (acetyl-CoA) catalyzed by acetyl-CoA carboxylase (ACC), the rate-limiting step in fatty acid biosynthesis. In this work, expression of Yarrowia lipolytica ACC in S. cerevisiae was attempted with the objective of establishing an alternative malonyl-CoA production system in this yeast. A S. cerevisiae strain with a tetracycline repressible ACC1 was used for functional testing. Since ACC1 is an essential gene, this strain is not capable of growing in medium supplemented with tetracycline. Expression of S. cerevisiae or Yarrowia lipolytica ACC1 from a plasmid complemented the conditional phenotype and enabled growth in tetracycline containing medium. Expression of ACCs from plasmids caused prolonged lag phase, and specific growth rates were considerably lower than the ones obtained for the wild type strain. This result is consistent with previous studies where ACC activity was increased and likely results from the metabolic imbalance this increase might cause. Results of in-vivo measurements of malony—CoA levels in the recombinant strain will be discussed.FatVal POCI-01-0145-FEDER-032506. Ph.D. scholarship SFRH/BD/140039/201

Economic efficiency of EMBRAPA’S research centers and the influence of contextual variables

Neste artigo é medida a eficiência econômica dos centros de pesquisa da Empresa Brasileira de Pesquisa Agropecuária (Embrapa). É usado o modelo DEA BCC, cuja medida de eficiência é modelada como função linear das variáveis contextuais capacidade de geração de receita, intensidade de parcerias, melhoria de processos administrativos, racionalização de custos, tamanho e tipo de centro. O modelo é do tipo painel dinâmico, assume correlação intra-temporal estruturada entre os centros de pesquisa e inter-temporal não estruturada. Para desempatar as unidades eficientes é usado um índice heurístico de eficiência que agrega os resultados de eficiência em relação às fronteiras DEA clássica e invertida. O efeito positivo das parcerias na medida de eficiência, invalida as críticas de que o processo de avaliação prejudica a integração e cooperação entre os centros de pesquisa. A melhoria de processos administrativos é a variável mais importante do ponto de vista da significância estatística das variáveis contextuais. _________________________________________________________________________________ ABSTRACTIn this paper we measure, with a DEA BCC model, the economic efficiency of Embrapa’s (Brazilian Agricultural Research Corporation) research centers. We model the DEA economic efficiency as a linear function of the contextual variables revenue generation capacity, partnership intensity, improvement of administrative processes, cost rationalization, size and type of research centers. The model used is of the type dynamic panel and assumes a structured correlation matrix intra times and unstructured inter times. In order to better discriminate the efficient units we used a heuristic efficiency score that aggregates the efficiencies in relation to the original and inverted DEA frontiers. Partnerships positive effect in the efficiency scores does not confirm the thoughts that Embrapa’s performance evaluation process discourages the integration and cooperation of its research centers. From the point of view of statistical significance, the improvement of administrative processes is the most important indicator among the contextual variables

Influence of aerobic fitness on the correspondence between heart rate variability and ventilatory threshold

The aims of this study were to verify the correspondence between heart rate variability (HRV) and ventilatory thresholds during a progressive exercise test and the relationship with low and high aerobic fitness levels. Twenty male volunteers (29.5±6.2 years; 75.9±13.0 kg; 175.0±7.4 cm) were recruited. The subjects were allocated to two groups according to their VO2max <48.8 ml•kg−1•min−1 (low cardiorespiratory fitness group) (n=10) and >48.81 ml•kg−1•min−1 (high cardiorespiratory fitness group) (n=10). A progressive test was performed, consisting of 3-min stages beginning at 25 watts and increasing by 25 watts every 3-min. The HRV threshold (HRVT) and ventilatory threshold (VT) analyses were performed through visual inspection. The comparisons with RMSSD values in percentage of maximum workload resulted in a higher effect size (ES) than the SDNN values. The VO2 in the high cardiorespiratory fitness group at VT (+32%), HRVTRMSSD (+27%), and HRVTSDNN (+31%) was signifi cantly higher compared to the group with low cardiorespiratory fitness. Higher values were observed for relative load (W•kg-1) at VT and HRVTSDNN in the high cardiorespiratory fitness group in comparison with the low cardiorespiratory fitness group (P<0.05), but no difference for VT and HRVTRMSSD. Signifi cant correlations between at VT and HRVTSDNN (r=0.77) were found only in the low cardiorespiratory fitness group. Cardiorespiratory fitness should be regarded as a factor for HRVT evaluation. The HRVTSDNN was closer to the VT in the low cardiorespiratory fitness group than the HRVTRMSSD, however, the use of vagal modulation assessed using the HRV parameter was more sensitive to observe possible differences regarding cardiorespiratory fitness.The aims of this study were to verify the correspondence between heart rate variability (HRV) and ventilatory thresholds during a progressive exercise test and the relationship with low and high aerobic fitness levels. Twenty male volunteers (29.5±6.2 years; 75.9±13.0 kg; 175.0±7.4 cm) were recruited. The subjects were allocated to two groups according to their VO2max <48.8 ml•kg−1•min−1 (low cardiorespiratory fitness group) (n=10) and >48.81 ml•kg−1•min−1 (high cardiorespiratory fitness group) (n=10). A progressive test was performed, consisting of 3-min stages beginning at 25 watts and increasing by 25 watts every 3-min. The HRV threshold (HRVT) and ventilatory threshold (VT) analyses were performed through visual inspection. The comparisons with RMSSD values in percentage of maximum workload resulted in a higher effect size (ES) than the SDNN values. The VO2 in the high cardiorespiratory fitness group at VT (+32%), HRVTRMSSD (+27%), and HRVTSDNN (+31%) was signifi cantly higher compared to the group with low cardiorespiratory fitness. Higher values were observed for relative load (W•kg-1) at VT and HRVTSDNN in the high cardiorespiratory fitness group in comparison with the low cardiorespiratory fitness group (P<0.05), but no difference for VT and HRVTRMSSD. Signifi cant correlations between at VT and HRVTSDNN (r=0.77) were found only in the low cardiorespiratory fitness group. Cardiorespiratory fitness should be regarded as a factor for HRVT evaluation. The HRVTSDNN was closer to the VT in the low cardiorespiratory fitness group than the HRVTRMSSD, however, the use of vagal modulation assessed using the HRV parameter was more sensitive to observe possible differences regarding cardiorespiratory fitness

Consequências dos atributos dos solos na produtividade e reposta à seca do eucalipto em dois tipos de clima no Brasil

The present study aimed to evaluate the correlations between productivity and eucalyptus drought (DR) response between soil attributes in two distinct climatic types in Brazil. For this, 24 experiments were installed in Brazil with four common clones in all the experiments to obtain strong edaphoclimatic contrasts, and, thus, to measure the productivity and the response to drought and to describe its relationship with the attributes of the soils. Two climatic groups were evaluated: Wet (precipitation rate: evapotranspiration between 1.0 to 2.5) and Sub-Humid (precipitation rate: evapotranspiration between 0.5 to 1.0). The attributes of the evaluated soils were: Sand, Silt, Clay, organic matter (O.M.), cation exchange capacity (CEC). For sites located in the wet climate class, CVWB correlated negatively with O.M. and clay, and positively with the sand. For DR, the correlations were observed for the Sub-Humid climate for the CEC and Sand variables, and for the Humid climate, no correlations were observed between the attributes of soils with DR.O objetivo do presente trabalho foi avaliar as correlações entre produtividade e resposta à seca (RS) do eucalipto entre os atributos do solo em dois tipos climáticos distintos no Brasil. Para isto, foram instalados 24 experimentos no Brasil com 4 clones comuns em todos os experimentos para obter fortes contrastes edafoclimáticos, e, desse modo, mensurar a produtividade e a reposta à seca e descrever as suas relações com os atributos de solos. Foram avaliados dois grupos climáticos: Úmido (relação precipitação: evapotranspiração entre 1,0 a 2,5) e Subúmido (relação precipitação: evapotranspiração entre 0,5 a 1,0). Os atributos dos solos avaliados foram: Areia, Silte, Argila, matéria orgânica (M.O.), capacidade de troca catiônica (CTC). Para os sítios localizados na classe climática Úmida, o VCCC correlacionouse negativamente com a M.O. e argila, e positivamente com a Areia. Para a RS, as correlações foram observadas para clima Subúmido para as variáveis CTC e Areia, e para o clima Úmido, não foram observadas correlações entre os atributos de solos com a RS

Intermittent administration of parathyroid hormone improves the repairing process of rat calvaria defects: a histomorphometric and radiodensitometric study

Background: The aim of this study was to evaluate the effects of intermittent treatment of parathyroid hormone (PTH (1-34)) on the bone regeneration of critically-sized rat calvarial bone defects. Material and Methods: Thirty-two male rats were trephined (4mm fullthickness diameter), in the central part of the parietal bones and divided into 2 groups of 16. The PTH group received subcutaneous injections of PTH (1-34) at 40μg/kg, 3 times a week and the control (CTL) group received the vehicle in the same regimen. The rats were sacrificed at 4 weeks post-treatment regimen, the parietal bones were extracted and samples were evaluated through histomorphometry and radiodensitometry. Results: The histological observations showed that the PTH group presented more “island-like” new bone between the defect margins with fibrous tissues than did the CTL group. The PTH group significantly exhibited greater histologic bone formation than did the CTL group (1.5mm ±0.7; 1.9 mm ± 0.6, p <0.05/ for residual bone defect). The radiodensitometry analysis revealed significant differences among the PTH and CTL groups (2.1 Al eq. ±0.04; 1.8Al eq. ±0.06, p <0.05), demonstrating an increase in bone mineral density. The PTH treatment contributed to the bone formation with a higher amount of mineral and/or fibrous tissue when compared with the CTL group. Conclusions: The results suggest that it was possible to increase the process of bone regeneration by accelerating the healing process in rat calvarial defects through intermittent administration of the PTH treatment

A novel D-xylose isomerase from the gut of the wood feeding patent-leather beetle Odontotaenius disjunctus

D-Xylose Isomerase (XI) is a key enzyme for the metabolism of D-xylose in renewable carbohydrate rich feedstocks such as lignocellulosic hydrolysates. The widely used industrial organism baker’s yeast Saccharomyces cerevisiae can metabolize xylose upon heterologous expression of this enzyme. This enzyme is notoriously difficult to express in S. cerevisiae and only about ten active genes are known from prokaryotic and eukaryotic sources. We cloned a new XI from microorganisms in the gut of the wood feeding beetle Odontotaenius disjunctus. The new enzyme was functionally screened from a pool of enzymes with potential XI activity based on its sequence similarity to XI from Piromyces sp. strain E2. Interestingly, the newly identified enzyme and XI from Piromyces shared the highest sequence identity among the assayed enzymes. Cells carrying the new XI grew in media with D-xylose as the sole carbon source at a superior rate to that of XI from Piromyces, yet at a considerably inferior rate to that of the alternative xylose reductase–xylitol dehydrogenase pathway. Furthermore, optimal conditions of temperature and pH, kinetic parameters, and inhibition kinetics by xylitol were determined for the new enzyme. The physiological characterization of D-xylose fermenting S. cerevisiae expressing the new XI will be further discusse