1,067 research outputs found
Credit of peanut to subsequent wheat under desert farming conditions in presence of diazotrophs and nitrogen fertilizers
Rotation with leguminous crops to break non-legume monocultures has been established to benefit the latter. The lacking information on this cultivation system in stressed environments encouraged the implementation of two field trials in two different locations of Ismailia desert soils. The experimental design included the cultivation of wheat subsequent to peanut in presence of diazotroph inoculation and N fertilization. Bradyrhizobial inoculation of the legume in combination with 50 kg N acre-1 resulted in the highest total biological yields of 4.24 and 5.01 kg plot-1 at the experimental sites 1 and 2, respective seed yields of 1.46 and 1.61 kg pot-1 were recorded. In case of the cereal crop, the measured acetylene reducing activities in soils of associative diazotroph-inoculated plants together with 50 kg N acre-1 were the highest being 515.8-886.2 and 616.7-1066.2 nmoles C2H4 g-1 h-1 at locations 1 and 2 respectively. The enzymatic activity of fallow-cultivated wheat generally represented ca. 95 % of that in subsequent to peanut. Irrespective of inoculation and N fertilization, the wheat biomass yield increases in residual effect-field over the fallow one were 6.4-35.1 % and 4.6-38.5 % at experimental sites 1 and 2 respectively. Increase percentages of 3.1-26.6 and 6.9-44.7 were scored as well for grain yield. The beneficial residual effect of the legume to the succeeding cereal was also extended to protein yields, increases of 4.0-14.2 % and 4.5-7.6 % were estimated for grain protein as well as 8.3-24.1 % and 8.1-35.3 % for straw protein yield. The findings of this study proved that the positively yield turnover of a legume is extended to the subsequent non-legume. Besides, the beneficial residual effects of legumes toward rotated non legumes could be magnified by diazotroph inoculation together with adequate N supply particularly in stressed environments represented, in the present study, by Ismailia sandy soil
Fine scale spatial variability of microbial pesticide degradation in soil: scales, controlling factors, and implications
Pesticide biodegradation is a soil microbial function of critical importance for modern agriculture and its environmental impact. While it was once assumed that this activity was homogeneously distributed at the field scale, mounting evidence indicates that this is rarely the case. Here, we critically examine the literature on spatial variability of pesticide biodegradation in agricultural soil. We discuss the motivations, methods, and main findings of the primary literature. We found significant diversity in the approaches used to describe and quantify spatial heterogeneity, which complicates inter-studies comparisons. However, it is clear that the presence and activity of pesticide degraders is often highly spatially variable with coefficients of variation often exceeding 50% and frequently displays nonrandom spatial patterns. A few controlling factors have tentatively been identified across pesticide classes: they include some soil characteristics (pH) and some agricultural management practices (pesticide application, tillage), while other potential controlling factors have more conflicting effects depending on the site or the pesticide. Evidence demonstrating the importance of spatial heterogeneity on the fate of pesticides in soil has been difficult to obtain but modelling and experimental systems that do not include soil’s full complexity reveal that this heterogeneity must be considered to improve prediction of pesticide biodegradation rates or of leaching risks. Overall, studying the spatial heterogeneity of pesticide biodegradation is a relatively new field at the interface of agronomy, microbial ecology, and geosciences and a wealth of novel data is being collected from these different disciplinary perspectives. We make suggestions on possible avenues to take full advantage of these investigations for a better understanding and prediction of the fate of pesticides in soil
Formulation, evaluation and optimization of miconazole nitrate tablet prepared by foam granulation technique
The aim of our study was to utilize novel foam granulation technique in formulation of miconazole nitrate; a model hydrophobic drug as oral disintegrating tablets "ODT" particularly to enhance its bioavailability. Foam granulation technique has additional advantages over the other traditional granulation technique since; it enhances the granulation process and produce acceptable tablets. Fractional factorial design was used to investigate the effect of formulation and processing variables on the prepared miconazole ODT. The prepared granules were evaluated by measuring their density, flowability, granules size and shape, and granules wetting time. The quality attributes of the prepared tablets; drug content, tablet thickness, uniformity of weight, tablet tensile strength, friability, disintegration, and dissolution were also evaluated. The results indicated that, the prepared granules showed acceptable characteristics and is significantly affected by the disintegrant type, urea concentration, and the lubricant type. The quality attributes of the tablets were not affected by the processing parameters. From the prepared formulas; F20, F19, F12, and F20 displayed 18, 35, 35, and 40 seconds disintegration time respectively and the percent of dissolution after 15 minutes ranged from 94.4-100%. These results ascertained that foam granulation technique fulfill the requirement in preparation of miconazole ODT. Key words: miconazole nitrate, foam granulation, oral disintegrating tablet
Flexural performance of reinforced concrete beams strengthened with prestressed near-surface-mounted FRP reinforcements
YesA numerical method for estimating the curvature, deflection and moment capacity of reinforced concrete beams strengthened with prestressed near-surface-mounted (NSM) FRP bars/strips is presented. A sectional analysis is carried out to predict the moment–curvature relationship from which beam deflections and moment capacity are then calculated. Based on the amount of FRP bars, different failure modes were identified, namely tensile rupture of prestressed FRP bars and concrete crushing before or after yielding of steel reinforcement. Comparisons between experimental results available in the literature and predicted curvature, moment capacity and deflection of reinforced concrete beams with prestressed NSM FRP reinforcements show good agreement. A parametric study concluded that higher prestressing levels improved the cracking and yielding loads, but decreased the beam ductility compared with beams strengthened with nonprestressed NSM FRP bars/strips
Theoretical study and analysis of o-nitrophenol adsorption using layered double hydroxides containing ca-al, ni-al and zn-al
A theoretical assessment of the o-nitrophenol adsorption on layered double hydroxides containing different metallic species (Ca-Al, Ni-Al and Zn-Al) was performed. Experimental o-nitrophenol adsorption isotherms obtained at different adsorption temperatures with these layered double hydroxides were analyzed using a statistical physics monolayer model. Model calculations showed that the o-nitrophenol aggregation could occur with a high degree. It was estimated that the o-nitrophenol adsorption implied a non-flat orientation on all adsorbent surfaces and this process was multi-molecular. It was also demonstrated that there was no significant difference on the o-nitrophenol adsorption capacities of tested adsorbents, which varied from 77 to 135, 95 to 122 and 74 and 130 mg/g for Ca-Al, Ni-Al and Zn-Al layered double hydroxides, respectively. This finding suggested that the incorporation of Ca-Al, Ni-Al and Zn-Al in the layered double hydroxide structure played a similar role to adsorb o-nitrophenol molecules from aqueous solution. Calculated adsorption energies and thermodynamic functions confirmed an exothermic adsorption with the presence of physical-based interaction forces. This paper highlights the importance of reliable theoretical calculations based on statistical physics theory to contribute in the understanding of the adsorption mechanisms of a relevant water pollutant using layered double hydroxides as promising adsorbents for industrial applications
First-in-human immunoPET imaging of COVID-19 convalescent patients using dynamic total-body PET and a CD8-targeted minibody
With most of the T cells residing in the tissue, not the blood, developing noninvasive methods for in vivo quantification of their biodistribution and kinetics is important for studying their role in immune response and memory. This study presents the first use of dynamic positron emission tomography (PET) and kinetic modeling for in vivo measurement of CD8+ T cell biodistribution in humans. A 89Zr-labeled CD8-targeted minibody (89Zr-Df-Crefmirlimab) was used with total-body PET in healthy individuals (N = 3) and coronavirus disease 2019 (COVID-19) convalescent patients (N = 5). Kinetic modeling results aligned with T cell-trafficking effects expected in lymphoid organs. Tissue-to-blood ratios from the first 7 hours of imaging were higher in bone marrow of COVID-19 convalescent patients compared to controls, with an increasing trend between 2 and 6 months after infection, consistent with modeled net influx rates and peripheral blood flow cytometry analysis. These results provide a promising platform for using dynamic PET to study the total-body immune response and memory
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