Arsenic and human health effects: A review Mohammed Abdul, Khaja Shameem; Jayasinghe, Sudheera Sammanthi; Chandana, Ediriweera P.S ...
Environmental toxicology and pharmacology,
11/2015, Letnik:
40, Številka:
3
Journal Article
Forest restoration is mainly based on plant-soil relationships and plant species with economic potential, but those between insects and other arthropods are also important to this reestablishment. ...The objective was to evaluate, during 24 months, the relationships between tending ants, Hemiptera phytophagous, predators and their distribution pattern (aggregated, random or uniform). The arthropods were sampled, stored and identified and their relationships and distribution patterns calculated with the BioDiversity-Pro software. The number of tending ants and phytophagous Hemiptera, Brachymyrmex sp. and Aethalion reticulatum, Cephalotes and Aleyrodidae were positively correlated. Tending ants were negatively correlated with Sternorrhyncha predators on A. auriculiformis saplings. The distribution of arthropods was aggregated, except for Teudis sp. and Cephalocoema sp., with a random pattern. The herbivores Stereoma anchoralis, Aethalion reticulatum and Tetragonisca angustula and the predators Brachymyrmex sp. and Dolichopodidae were the most abundant arthropods. The relationships between the arthropods studied on A. auriculiformis indicate that this plant, even introduced, is suitable for programs to recover degraded areas in the savannah.
Abstract The effect of environmental gradients on the remarkable diversity of mountain‐associated plants and on the species' abilities to cope with climate change transcends species‐specific ...strategies. For instance, our understanding of the impact of thermal gradients on ecological divergences in populations of widely distributed species is limited, although it could provide important insights regarding species' response to climate change. Here, we investigated whether populations of an endemic species broadly distributed across an elevation gradient employ unique or multiple divergent ecological strategies according to specific environmental conditions. We hypothesised that populations employ distinct strategies, producing a tolerance‐avoidance trade‐off related to the thermal conditions they experience across elevations. We conducted our research with 125 individuals of Pitcairnia flammea (Bromeliaceae) sampled from various elevations spanning from sea level to ~2200 m and cultivated under the same conditions. To assess specific ecological strategies of P. flammea populations across elevations, we examined leaf temperature, heat and cold tolerances, as well as other structural/morphological, optical, physiological and biochemical leaf traits. We majorly observed that water‐saving traits diminish as elevation increases while membrane fluidity, majorly associated with unsaturated and very‐long‐chain lipids, enhances. Low‐elevation individuals of P. flammea invest in water storage tissues, which likely prevent excessive water loss through the intense transpiration rates under warming periods. Conversely, high‐elevation plants exhibit increased membrane fluidity, a possible response to the stiffening induced by low temperature. Our results revealed a tolerance‐avoidance trade‐off related to thermal strategies of populations distributed across an elevation gradient. Low‐elevation plants avoid excessive leaf temperature by investing in water‐saving traits to maintain transpiration rates. High‐elevation individuals, in turn, tend to invest in membrane properties to tolerate thermal variations, particularly cold events. Our findings challenge the conventional notion that plants' vulnerability to warming depends on species‐specific thermal tolerance by showing diverse thermal strategies on populations across an elevation gradient. Read the free Plain Language Summary for this article on the Journal blog.
Resumo O efeito dos gradientes ambientais na grande diversidade de plantas associadas a montanhas transcende as estratégias específicas de cada espécie. Nosso entendimento sobre o impacto dos gradientes térmicos nas divergências ecológicas em populações de espécies amplamente distribuídas, por exemplo, é limitado, embora possa fornecer informações importantes sobre a resposta das espécies às mudanças climáticas. Aqui, investigamos se populações de uma espécie endêmica e amplamente distribuída em um gradiente altitudinal, empregam estratégias ecológicas únicas ou múltiplas de acordo com condições ambientais específicas. Nossa hipótese é que as populações empregam estratégias que resultam em um equilíbrio entre tolerância e evitação relacionado às condições térmicas que experimentam em diferentes altitudes. Analisamos 125 indivíduos de Pitcairnia flammea (Bromeliaceae) amostrados em diversas altitudes, desde o nível do mar até cerca de 2.200 metros, e cultivados nas mesmas condições. Para avaliar as estratégias ecológicas específicas das populações de P. flammea , examinamos temperatura foliar, tolerâncias ao calor e ao frio, além de outros traços foliares estruturais/morfológicos, óticos, fisiológicos e bioquímicos. Vimos que características de economia de água diminuem à medida que a altitude aumenta, enquanto a fluidez da membrana, associada principalmente a lipídios insaturados e de cadeia muito longa, aumenta. Indivíduos de baixa altitude investem em tecidos de armazenamento de água, provavelmente prevenindo a perda excessiva de água durante períodos de aquecimento e com taxas intensas de transpiração. Por outro lado, plantas de altas altitudes possuem maior fluidez de membrana, uma possível resposta ao enrijecimento induzido por baixas temperaturas. Nossos resultados revelaram um equilíbrio entre tolerância e evitação relacionado às estratégias térmicas de populações distribuídas ao longo de um gradiente de altitude. Plantas de baixa altitude evitam temperaturas foliares excessivas investindo em características de economia de água para manter as taxas de transpiração. Indivíduos de alta altitude, por sua vez, tendem a investir em membranas que toleram variações térmicas, especialmente eventos frios. Nossas descobertas desafiam a noção convencional de que a vulnerabilidade das plantas ao aquecimento depende da tolerância térmica específica da espécie, mostrando estratégias térmicas diversas em populações ao longo de um gradiente de altitude.
In Brazil, the snail Biomphalaria glabrata is the most important vector of schistosomiasis due to its wide geographical distribution, high infection rate and efficient disease transmission. Among the ...methods of schistosomiasis control, the World Health Organization recommends the use of synthetic molluscicides, such as niclosamide. However, different substances of natural origin have been tested as alternatives for the control or eradication of mollusks. The literature describes the antitumor, antimicrobial and antiviral properties of usnic acid as well as other important activities of common interest between medicine and the environment. However, usnic acid has a low degree of water solubility, which can be a limiting factor for its use, especially in aquatic environments, since the organic solvents commonly used to solubilize this substance can have toxic effects on aquatic biota. Thus, the aim of the present study was to test the potassium salt of usnic acid (potassium usnate) with regard to molluscicidal activity and toxicity to brine shrimp (Artemia salina). To obtain potassium usnate, usnic acid was extracted with diethyl ether isolated and purified from the lichen Cladonia substellata. Biological assays were performed with embryos and adult snails of B. glabrata exposed for 24 h to the usnate solution solubilized in dechlorinated water at 2.5; 5 and 10 µg/ml for embryos, 0.5; 0.9; 1;5 and 10 µg/ml for mollusks and 0.5; 1; 5; 10 µg/ml for A. salina. The lowest lethal concentration for the embryos and adult snails was 10 and 1 µg/ml, respectively. No toxicity to A. salina was found. The results show that modified usnic acid has increased solubility (100%) without losing its biological activity and may be a viable alternative for the control of B. glabrata.
•MgO nanoparticles were synthesised using a novel in-situ method.•Chitosan/MgO nanocomposite thin films were fabricated by solution casting method.•The addition of MgO into chitosan resulted in 86% ...improvement in tensile stress.•Chitosan/MgO nanocomposites exhibited higher thermal stability and flame retardancy.•Chitosan with MgO nanoparticles also showed superior UV-shielding abilities.
Chitosan nanocomposite thin films were fabricated by incorporating MgO nanoparticles to significantly improve its physical properties for potential packaging applications. A novel in-situ method was developed to synthesise spherical shaped MgO nanoparticles by heat-treating magnesium carbonate/poly(methyl methacrylate) (PMMA) composite precursor. Optimum mechanical properties of chitosan composites were yielded at 5 (w/w%) of MgO concentration, where tensile stress and elastic modulus significantly improved by 86% and 38%, respectively, compared to those of pure chitosan films. These improvements are due to the interaction of hydroxyl and amine groups of chitosan with MgO as confirmed by FTIR spectroscopy. Fracture surface morphology indicated the interplay between MgO dispersion and aggregation on the mechanical properties at different MgO concentrations. Furthermore, the chitosan/MgO nanocomposites displayed remarkable thermal stability, flame retardant properties (satisfied V0 rating according to the UL-94 standards), UV shielding and moisture barrier properties, which could certainly add value to the packaging material.
Uniform and porous graphene nanoflake films (GNFs) have been investigated as a support for catalytic Pt nanoclusters in direct methanol electro-oxidation. Pt nanoclusters of varying thickness are ...deposited on GNFs using magnetron sputtering, and their effects on the electrocatalytic activity for oxidizing methanol are systemically studied. GNF supported Pt nanoclusters with ultralow catalyst loading exhibit high performance for methanol electrocatalytic oxidation with a large mass-specific peak current density and a ratio of forward to backward peak currents up to 1.4. These characteristics compare favorably to the majority of Pt−C based electrodes, except for those of carbon nanotubes with Pt decoration on both the inner and the outer wall surfaces. The results obtained are ascribed to a highly coupled network made of high-density 2−4 nm Pt monolayer nanoclusters on both the basal and edge planes of each nanoflakes of graphene. GNFs are a promising support material for developing next-generation advanced Pt based fuel cells and their relevant electrodes in the field of energy.
Mastitis is one of the most important causes of loss of cattle production, burdening producers due to the increased cost of milk production and decreased herd productivity. The development of ...alternative methods for the treatment and prevention of mastitis other than traditional chemical antibiotic therapy needs to be implemented to meet international pressures to reduce the use of these drugs and promote the elimination of multiresistant microbial strains from the environment. Treatment with probiotic bacteria or yeast strains offers a possible strategy for the control of mastitis. The objective of this work was to isolate, identify, and characterize lactic bacteria from milk and the intramammary duct of Gyr, Guzerat, Girolando 1/2, and Holstein cattle breeds from Brazil. Samples of 115 cows were taken, a total of 192 bacteria isolates belonging to 30 species were obtained, and 81 were selected to evaluate their probiotic potential in in vitro characterization tests. In general, bacteria isolated from the mammary gland have low autoaggregation, cell surface hydrophobicity, and co-aggregation with mastitis etiological bacteria Staphylococcus aureus and Escherichia coli. Also, they have biofilm assembly capacity, inability to produce exopolysaccharides, high production of H
O
, and strong antagonism against mastitis pathogens. Ten lactic bacteria isolates were used in co-culture with human MDA-MB-231 breast epithelial cells to assess their adhesion capacity and impairment of the S. aureus invasion. Our results, therefore, contribute to the future production of new prevention and treatment tools for bovine mastitis.
Silicon has been regarded as an attractive high‐capacity anode material for next‐generation lithium‐ion batteries (LIBs). However, Si anodes suffer from huge volume variation during cycling, which ...poses a critical challenge for stable battery operation. Compared with Si, Si suboxide (SiOx) is one of the most promising candidates for high‐energy‐density LIBs because of its alleviated swelling and highly stable cycling performance. Whereas, the poor electronic conductivity and low (initial) Coulombic efficiency of SiOx anodes severely hinder practical applications for LIBs. Herein, for the first time, these issues are successfully solved through rationally designing hollow‐structured SiOx@carbon nanotubes (CNTs)/C architectures with graphitic carbon coatings and in situ growth of CNTs. When applied as anodes in LIBs, the SiOx@CNTs/C anodes exhibit high reversible capacity, high initial Coulombic efficiency (88%), outstanding cycling performance, and extraordinary mechanical strength during the calendaring process (200 MPa). This work paves the way for developing SiOx‐based anode materials for high‐energy‐density LIBs.
A hollow‐structured silicon suboxide composite (SiOx@CNTs/C) with graphitic carbon coatings and in situ growth of carbon nanotubes is successfully synthesized. The as‐prepared anode materials exhibit superior rate capability, excellent cycling stability, and extraordinary mechanical strength with high initial Coulombic efficiency as an anode in lithium‐ion batteries.
In this Phase 2b study, 331 low‐to‐moderate risk de novo kidney transplant patients (approximately 60% deceased donors) were randomized to a more intensive (MI) or less intensive (LI) regimen of ...tofacitinib (CP‐690, 550), an oral Janus kinase inhibitor or cyclosporine (CsA). All patients received basiliximab induction, mycophenolic acid and corticosteroids. Primary endpoints were: incidence of biopsy‐proven acute rejection (BPAR) with a serum creatinine increase of ≥0.3 mg/dL and ≥20% (clinical BPAR) at Month 6 and measured GFR at Month 12. Similar 6‐month incidences of clinical BPAR (11%, 7% and 9%) were observed for MI, LI and CsA. Measured GFRs were higher (p < 0.01) at Month 12 for MI and LI versus CsA (65 mL/min, 65 mL/min vs. 54 mL/min). Fewer (p < 0.05) patients in MI or LI developed chronic allograft nephropathy at Month 12 compared with CsA (25%, 24% vs. 48%). Serious infections developed in 45%, 37% and 25% of patients in MI, LI and CsA, respectively. Anemia, neutropenia and posttransplant lymphoproliferative disorder occurred more frequently in MI and LI compared with CsA. Tofacitinib was equivalent to CsA in preventing acute rejection, was associated with improved renal function and less chronic allograft histological injury, but had side‐effects at the doses evaluated.
The authors present the results of a phase 2b trial of tofacitinib in renal transplantation.
ZnO nanostructures with different morphologies (nanowires, nanodisks, and nanostars) were synthesized hydrothermally. Gas sensing properties of the as-grown nanostructures were investigated under ...thermal and UV activation. The performance of the ZnO nanodisk gas sensor was found to be superior to that of other nanostructures (S g ∼ 3700% to 300 ppm ethanol and response time and recovery time of 8 and 13 s). The enhancement in sensitivity is attributed to the surface polarities of the different structures on the nanoscale. Furthermore, the selectivity of the gas sensors can be achieved by controlling the UV intensity used to activate these sensors. The highest sensitivity value for ethanol, isopropanol, acetone, and toluene are recorded at the optimal UV intensity of 1.6, 2.4, 3.2, and 4 mW/cm2, respectively. Finally, the UV activation mechanism for metal oxide gas sensors is compared with the thermal activation process. The UV activation of analytes based on solution processed ZnO structures pave the way for better quality gas sensors.
PDF
