An equal sex ratio followed by differential sex mortality causes overestimation of females in gall midges: no evidence for sex ratio regulation

Monogeny, the production of unisexual broods by individual females, has been recognized for nearly 80?years. The genetic nature of gall midges' sex determination predicts an equal numbers of male-producing and female-producing females in the populations such that the overall sex ratio is expected to be nearly 1:1. However, observations of some strictly monogenous populations with biased sex ratio, mainly toward females, have raised the question of whether gall midges are able to adjust their offspring sex ratio in response to changes in environmental conditions, and some authors have even considered sex ratio regulation as a strong force in the course of the evolution of monogeny. In this paper, first, by studying the sex ratio variations of the predatory gall midge, Aphidoletes aphidimyza within a generation, we showed that adult males emerge up to 1?day earlier and have shorter life span than females (less than 4?days and up to 6?days, respectively). Although, the sex ratio of A. aphidimyza at the time of emergence was nearly 1:1 (52.41?% males), a simple population simulation indicated that the differential mortality of sexes can lead to a female-biased sex ratio estimation (57.88?% females) under random sampling in the natural environments. Our results imply that the primary sex ratio of monogenous gall midges is nearly 1:1 and that the arrhenogenic/thelygenic gall midges are not able to alter the number of their male/female progenies in response to changes in environmental conditions.     

Stand-alone PV-hydrogen energy system in Taleghan-Iran using HOMER software: optimization and techno-economic analysis

One of the most attractive features of hydrogen as an energy carrier is that it can be produced from water. Hydrogen has the highest energy content per unit mass as compared to chemical fuel and can be substituted. Its burning process is non-polluting, and it can be used in the fuel cells to produce both electricity and useful heat. Photovoltaic arrays can be used in supplying the water electrolysis systems by their energy requirements. During the daylight hours, the sunlight on the photovoltaic array converts into electrical energy which can be used for electrolyzer. The hydrogen produced by the electrolyzer is compressed and stored in hydrogen vessel and provides energy for the fuel cell to meet the load when the solar energy is insufficient. This study investigates a stand-alone power system that consists of PV array as power supply and electrolyzer. They have been integrated and worked at the Taleghan renewable energies’ site in Iran. The National Renewable Energy Laboratory’s Hybrid Optimization Model for Electric Renewables simulation software has been used to carry out the optimal design and techno-economic viability of the energy system. The simulation results demonstrate that energy system is composed of 10-kW PV array, 3.5-kW electrolyzer, 0.4-kW proton exchange membrane fuel cell, 2.5-kW inverter, and 60 batteries (100 Ah and 12 V). The total initial capital cost, net present cost, and cost of electricity produced from this energy system are 193,563 US$, 237,509 US$, and 3.35 US$/kWh, respectively.     

Hydrogeochemical assessment of carcinogenic and non-carcinogenic health risks of potentially toxic elements in aquifers of the Hindukush ranges,Pakistan: insights from groundwater pollution indexing,GIS-based,and multivariate statistical approaches

Environmental Science and Pollution Research - Globally, potentially toxic elements (PTEs) and bacterial contamination pose health hazards, persistency, and genotoxicity in the groundwater aquifer....     

Optimization of metal bio-acid leaching from mobile phone printed circuit boards using natural organic acids and H2O2

Journal of Material Cycles and Waste Management - With increased popularity and technological innovation, more and more electric and electronic equipment wastes (e-wastes) are being generated....     

Design and optimization of new La1−xCexNi1−yFeyO3 (x,y = 0–0.4) nano catalysts in dry reforming of methane

The paper reports the production of syngas from dry reforming of methane (DRM) over La_1?xCe_xNi_1?yFe_yO₃ (x, y = 0–0.4) perovskites. A series of La_1?xCe_xNi_1?yFe_yO₃ were designed by central composite design (CCD) and synthesized by a sol–gel auto combustion method. Artificial neural network (ANN) approach was used to determine the relationship between preparation and operational parameters on the performance of the catalysts in the DRM process. Nickel mole fraction, lanthanum mole fraction, calcination temperature, and reaction temperature were considered as input variables, and conversion of methane was considered as the output variable. An ANN model with nine neurons in the hidden layer was the suitable in predicting conversion of methane. The genetic algorithm (GA) was subsequently used to determine the optimal preparation condition for enhancing the conversion of methane. La_0.6Ce_0.4Ni_0.99Fe_0.01O₃ catalyst, calcined at 756°C was obtained to be the most active catalyst owing to the optimal composition of nickel and lanthanum in the catalyst formulation.     

Kinetics and thermodynamics studies of cobalt,strontium and caesium sorption on marble from aqueous solution

Adsorption onto solid phases plays an important role in the transport of radionuclides and contaminants in the environment. Radionuclides in radioactive waste have been considered to be hazardous pollutants, and their migration with groundwater is strongly affected by sorption on the geologic media. Therefore, the knowledge of radionuclide sorption is of great importance in the management of radioactive wastes. A series of batch sorption experiments were conducted separately to investigate sorption and transport behaviour of cobalt, strontium and caesium on and through marble. Batch-mode kinetic and equilibrium studies have been carried out at different temperatures. Sorption experimental data were analysed by kinetic and isotherm models. Based on the results obtained, it can be concluded that the marble is an economic and efficient retaining material for environmental hazardous migration and/or leakage of some radionuclides. Therefore, this study could be used as a starting point to establish and consider that rock as a reactive barrier around the disposal facilities at the nuclear activity centres.     

Comparative phytotoxicity of ZnO nanoparticles,ZnO microparticles,and Zn2+ on rapeseed (Brassica napus L.): investigating a wide range of concentrations

The effects of ZnO nanoparticles (NPs), ZnO microparticles (MPs), and zinc ions (Zn²⁺) on some growth parameters of rapeseed (Brassica napus) seedlings have been studied. The growth inhibition by ZnO NPs was not stronger than that by ZnO MPs while treatment with Zn²⁺ inhibition was clearly stronger.     

The effect of EDDS and citrate on the uptake of lead in hydroponically grown Matthiola flavida

Root and shoot lead concentrations and the impact of chelating agents on these were investigated in two populations of the novel metallophyte Matthiola flavida. Plants were exposed in hydroponics to Pb(NO₃)₂, supplied alone, or in combination with citric acid, or EDDS. When supplied at concentrations expected to bind about 95% of the Pb in a solution containing 1-μM Pb (1000 μM citrate or 3.1 μM EDDS, respectively), the root and shoot Pb concentrations were dramatically lowered, in comparison with a 1-μM free ionic Pb control exposure. A 1-mM EDDS + 1-μM Pb treatment decreased the plants’ Pb concentrations further, even to undetectable levels in one population. At 100 μM Pb in a 1-mM EDDS-amended solution the Pb concentration increased strongly in shoots, but barely in roots, in comparison with the 1-μM Pb + 1-mM EDDS treatment, without causing toxicity symptoms. Further increments of the Pb concentration in the 1-mM EDDS-amended solution, i.e. to 800 and 990 μM, caused Pb hyperaccumulation, both in roots and in shoots, associated with a complete arrest of root growth and foliar necrosis. M. flavida seemed to be devoid of constitutive mechanisms for uptake of Pb-citrate or Pb-EDDS complexes. Hyperaccumulation of Pb-EDDS occurred only at high exposure levels. Pb-EDDS was toxic, but is much less so than free Pb. Free EDDS did not seem to be toxic at the concentrations tested.     

Simultaneous spectrophotometric determination of crystal violet and malachite green in water samples using partial least squares regression and central composite design after preconcentration by dispersive solid-phase extraction

In this paper, a simple, fast, and inexpensive method is introduced for the simultaneous spectrophotometric determination of crystal violet (CV) and malachite green (MG) contents in aquatic samples using partial least squares regression (PLS) as a multivariate calibration technique after preconcentration by graphene oxide (GO). The method was based on the sorption and desorption of analytes onto GO and direct determination by ultraviolet–visible spectrophotometric techniques. GO was synthesized according to Hummers method. To characterize the shape and structure of GO, FT-IR, SEM, and XRD were used. The effective factors on the extraction efficiency such as pH, extraction time, and the amount of adsorbent were optimized using central composite design. The optimum values of these factors were 6, 15 min, and 12 mg, respectively. The maximum capacity of GO for the adsorption of CV and MG was 63.17 and 77.02 mg g^?1, respectively. Preconcentration factors and extraction recoveries were obtained and were 19.6, 98% for CV and 20, 100% for MG, respectively. LOD and linear dynamic ranges for CV and MG were 0.009, 0.03–0.3, 0.015, and 0.05–0.5 (μg mL^?1), respectively. The intra-day and inter-day relative standard deviations were 1.99 and 0.58 for CV and 1.69 and 3.13 for MG at the concentration level of 50 ng mL^?1, respectively. Finally, the proposed DSPE/PLS method was successfully applied for the simultaneous determination of the trace amount of CV and MG in the real water samples.