4,698 research outputs found

    Physicochemical and mineral properties of suspended sediments of the Tigris and Euphrates rivers in the Mesopotamian Plain

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    Most of the suspended river load from the Tigris and Euphrates rivers is deposited in the Mesopotamian Plain in Iraq. This suspended river load comprises sediments consisting of minerals and organic particles generated from weathering, erosion, transport, and sedimentation. Therefore, it is crucial to analyze, either quantitative or qualitatively, the types of minerals in the sediment particles transported by the suspended river load, in addition to the potential value they may add to the agricultural lands irrigated by the Tigris and Euphrates rivers. Herein, samples of suspended sediments were collected from both rivers for physical, chemical, and mineral assessments. The results revealed the predominance of silt particles, followed by clay, and then sand. The presence of clay particles increased while that of silt and sand decreased with further travel into the rivers. The pH values ranged from 7.39 to 7.70 and the electrical conductivity ranged from 1.39 to 2.16 ds m����� 1. The values of the total and active calcium carbonate minerals were 352.87–336.12 and 172.64–194.56 g kg����� 1 for the Tigris and Euphrates rivers, respectively. The mineral analysis identified the presence of non-clay minerals at a rate of 83 %, including calcite, quartz, albite, dolomite, and gypsum. Clay minerals, including chlorite, illite, montmorillonite, palygorskite, vermiculite, and kaolinite, were found at a rate of 17 %. Both rivers exhibited distributions of clay and non-clay minerals that vary as they move along the rivers

    Activated carbon from grape seeds upon chemical activation with phosphoric acid: Application to the adsorption of diuron from water

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    The preparation of activated carbon from grape seeds was studied by chemical activation with phosphoric acid. Grape seeds were pretreated with sulfuric acid to improve wettability and impregnated at different grape seed to phosphoric acid ratios (1:1-1:4). The impregnated grape seeds were carbonized in a static horizontal furnace at temperatures between 350 and 550°C. Microporous activated carbons with some contribution of mesoporosity were obtained. The best results in terms of surface area (1139m2/g) and mesopore volume (0.24cm3/g) development were observed for a grape seeds to phosphoric acid ratio of 1:3 and a carbonization temperature of 500°C. The activated carbon prepared shows granular morphology and an egg shell structure that favors application in liquid phase. The activated carbon was tested in the adsorption of diuron from aqueous phase. The adsorption rate was measured within the temperature range of 15-45°C. First and second order rate equations and intraparticle diffusion model were checked to fit the kinetic dataWe greatly appreciate financial support from the Spanish MCYT (CTQ2009-09983 and CSD2006-44) and CAM (REMTAVARES S-2009/AMB-1588). M. Al Bahri thanks to the Spanish MICINN a research grant (CTQ2006-13512

    Optimizing sustainable agriculture: A comprehensive review of agronomic practices and their impacts on soil attributes

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    This study explores agronomic management (AM) effects on soil parameters under diverse conditions. Investigating tillage practices (TP), nutrient management (NM), crop rotation (CR), organic matter (OM), irrigation management (IM), and mulching (MS), it aims to reveal impacts on soil productivity, nutrient availability, microbial activity, and overall health. Varied TP affect soil quality through compaction, porosity, and erosion risk. Proper NM is vital for nutrient cycling, preventing imbalances and acidification. CR disrupts pest cycles, reduces weed pressure, and boosts nutrient recycling. OM management enhances soil quality by influencing organic carbon, nutrient availability, pH, fertility, and water retention. Optimizing IM regulates soil water content without inducing waterlogging. MS contributes to OM content, nutrient retention, soil structure, and temperature-moisture regulation, benefiting soil biota, aggregation, soil health and agricultural productivity. The review emphasizes integrated nutrient, CR, and OM management’s positive impact on fertility and microbial activity. Different TP and IM variations impact soil health and crop production. Judicious implementation of these practices is essential for sustainable agriculture. This synthesis identifies uncertainties and proposes research directions for optimizing productivity while ensuring environmental sustainability. Ongoing inquiry can guide a balanced approach between yields and resilient soil stewardship for future generations.Universidad de Granada / CBU

    A novel heat-pulse probe for measuring soil thermal conductivity: Field test under different tillage practices

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    Accurate soil thermal conductivity (λ) measurements are needed in experimental agri-environmental research. This study design and build of new heat-pulse probe (HPP) based on transient state technology to measure λ. The HPP consists of three main components: an electronic control system, a measurement chamber, and sample rings. The performance of the new HPP for in-situ λ measurements is compared to estimates from measurable soil physical properties (pedotransfer function). Tests were conducted in clay loam and loam soils at three depths. λ measurements by the HPP were affected by tillage practice, fertilizer treatment, soil depth, and soil type. No significant differences in λ measurements by the HPP and estimates from a pedotransfer function were found between tillage practices. There were positive correlations between their values at three soil depths: R2 = 0.92 at 0–5 cm depth, and R2 = 0.88 at both 5–10 and 10–15 cm depths. The standard deviation from the HPP measurements were 0.061, 0.077, and 0.080 W·m−1·K−1 at 0–5, 5–10, and 10–15 cm depths, respectively. In contrast, the pedotransfer function estimates had standard deviations of 0.085, 0.660, and 0.083 W·m−1·K−1, respectively. It was found that conventional tillage increases temperature flow in soils compared to no-tillage because of decreasing soil bulk density (ρb) and consequently higher porosity. The proposed HPP is a low-cost and energy-efficient device, with wide applicability under a range of conditions. It is highly recommended for measuring λ clay loam and loam soils; however, more research is needed to determine its value with other soil types

    Perkinsus marinus tissue distribution and seasonal variation in oysters Crassostrea virginica from Florida, Virginia and New York

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    Perkinsus marinus infection intensity was measured in eastern oysters Crassostrea virginica collected in October and December 1993, and March, May, and July 1994 from 3 U.S. sites: Apalachicola Bay (FL), Chesapeake Bay (VA), and Oyster Bay (Mr\u27). Gill, mantle, digestive gland. adductor muscle, hemolymph, and remaining tissue (including gonadal material and rectum) were dissected from 20 oysters from each site at each collection time. Samples were separately diagnosed for P. marin us infections by incubation in Ray\u27s Fluid Thioglycollate Medium (RFTM) and subsequent microscopic quantification of purified enlarged hypnospores. At all sampling times and sites, average P. marinus infection intensity (g wet wt tissue(-1) or ml hemolymph(-1)) was lowest in hemolymph samples, and generally highest in the digestive gland. Perkinsus marinus prevalence was 100% at both FL and NY sites for each of the 5 collection times, and, for the VA site, was less than 100% in only 1 month (May 1994). Seasonal intensity patterns and mean total body burdens differed among the sites. Average body burden was highest in VA during October and progressively declined to a minimum in May. This decline was probably due to mortality of heavily infected oysters and diminution of parasite activity associated with colder temperatures and reduced salinities. Intensities varied little during the months of October and December at both the FL and NY sites. Minimum average intensities were observed in March in FL oysters and May in NY oysters. Relatively high P. marinus infection levels that persisted throughout the winter in NY oysters compared with VA oysters could reflect constant high salinity in Long Island Sound which favors parasite activity, and also rapid decline in temperature in the fall that may have prevented epizootic oyster mortalities

    Cost-effectiveness of two dry needling interventions for plantar heel pain: A secondary analysis of an rct

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    Plantar heel pain is a common cause of foot pain that affects patients’ quality of life and represents a significant cost for the healthcare system. Dry needling and percutaneous needle electrolysis are two minimally invasive treatments that were shown to be effective for the management of plantar heel pain. The aim of our study was to compare these two treatments in terms of health and economic consequences based on the results of a published randomized controlled trial. For this, we evaluated the costs from the point of view of the hospital and we carried out a cost-effectiveness study using quality of life as the main variable according to the Eq-5D-5L questionnaire. The cost of the complete treatment with dry needling (DN) was €178.86, while the percutaneous needle electrolysis (PNE) was €200.90. The quality of life of patients improved and was translated into +0.615 quality-adjusted life years (QALYs) for DN and +0.669 for PNE. PNE presented an average incremental cost-effectiveness ratio (ICER) of €411.34/QALY against DN. These results indicate that PNE had a better cost-effectiveness ratio for the treatment of plantar heel pain than DN

    The Visual Construction of the Umayyad Caliphate in Al-Andalus through the Great Mosque of Cordoba

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    My first exposure to the epigraphic program of the Great Mosque of Cordoba, published in 2001, came from reading an article on the ideological meaning of the decoration and the Quranic citations inscribed in al-H. akam II’s addition to the building. In that article, I concluded that the Quranic verses found in the mosque were chosen not only for being a universal proclamation of divine power and praise for the Umayyad dynasty, as proposed by Nuha Khoury in 1996, but also because they clearly fitted in with the particular Andalusi, or rather Cordoban, religious, cultural, and political context in the first half of the 10th century. Most of the inscriptions had been read in the 19th century by Amador de los Ríos, but some of them remained uninterpreted. Given that they were an essential part of the ideological message, it seemed appropriate to revisit the critical reading of the epigraphic program and determine its full meaning. Later, I discussed other architectural aspects of the Great Mosque in which the links to the Andalusi and the eastern Umayyad traditions are a key aspect in understanding why these forms were chosen. Damascus, the eastern Umayyad capital, and to a lesser extent Medina and the Abbasid capitals, became the model for the caliphs of Cordoba. This article proposes to revisit the main architectural and decorative features of the caliphal enlargements of the Great Mosque of Cordoba in order to reflect on the meaning and forms of its epigraphic program

    Mechanistic understanding of the behavior of diuron in the adsorption from water onto activated carbon

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    The adsorption of diuron from aqueous phase by activated carbon has been analyzed from a molecular point of view thanks to a computational approach based on COSMO-RS methodology, with the aim of providing a mechanistic explanation of the experimental results. The adsorption experiments were carried out at different pH values (3-7) and temperatures (15-45 °C) using an activated carbon prepared by chemical activation of grape seeds. The most relevant characteristics of the adsorption of diuron were the increase of diuron uptake with temperature and the occurrence of multilayer adsorption at high equilibrium concentrations. Likewise, the contribution of cooperative adsorption was also found to increase with temperate, as shown by the change of the isotherm pattern from L-3 type (Giles classification) at 15 °C to S-3 at 45 °C. The formation of multilayer and the contribution of cooperative adsorption were not observed at the highest pH studied The results obtained from the computational approach were consistent with the trends shown by the experimental data. The molecular and thermodynamic properties of the solvent-adsorbate-adsorbent system were estimated using the quantum-chemical COSMO-RS method. Thus, the increase in diuron uptake at increasing temperature was ascribed to a higher population of diuron planar conformers, whose affinity for activated carbon is higher as evaluated in terms of the activated carbon/water partition coefficient. COSMO-RS simulations predicted strong interaction among diuron molecules due to the amphoteric character of the molecule. Likewise, the formation of clusters was found to be especially favored from a thermodynamic point of view in the case of planar conformers adsorbed on activated carbon, which supports the occurrence of cooperative adsorption and the formation of a multilayerWe greatly appreciate financial support from the Spanish MCYT (CTQ2009-09983 and CSD2006-44) and CAM (REMTAVARES S-2009/AMB-1588

    Airlift bioreactor for biological applications with microbubble mediated transport processes

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    Airlift bioreactors can provide an attractive alternative to stirred tanks, particularly for bioprocesses with gaseous reactants or products. Frequently, however, they are susceptible to being limited by gas–liquid mass transfer and by poor mixing of the liquid phase, particularly when they are operating at high cell densities. In this work we use CFD modelling to show that microbubbles generated by fluidic oscillation can provide an effective, low energy means of achieving high interfacial area for mass transfer and improved liquid circulation for mixing. The results show that when the diameter of the microbubbles exceeded 200 µm, the “downcomer” region, which is equivalent to about 60% of overall volume of the reactor, is free from gas bubbles. The results also demonstrate that the use of microbubbles not only increases surface area to volume ratio, but also increases mixing efficiency through increasing the liquid velocity circulation around the draft tube. In addition, the depth of downward penetration of the microbubbles into the downcomer increases with decreasing bubbles size due to a greater downward drag force compared to the buoyancy force. The simulated results indicate that the volume of dead zone increases as the height of diffuser location is increased. We therefore hypothesise that poor gas bubble distribution due to the improper location of the diffuser may have a markedly deleterious effect on the performance of the bioreactor used in this work
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