A variant of a simple sampling Monte Carlo technique is applied to study the configurational statistics of models for short isolated polyethylene chains, taking into account variations of the bond lengths, the bond angles, and the torsional angles as well as a Lennard-Jones (LJ) potential between nonbonded neighbors. The dependence of the mean-square end-to-end distance (R2), of the gyration radius (Rg2), and of their ratio ), where l stands for the length of groups formed from n successive monomers and for the angle between two such successive groups. In a -solvent or a dense melt the LJ interaction will be screened due to the polarizability of the solvent or due to other chains, respectively. We model this with a cutoff in the LJ interaction and show that all data depend very sensitively on the way in which the Lennard-Jones potential is truncated. Furthermore, we note that different potential models for polyethylene yield significantly different results. In view of these problems, it is not obvious that one can identify such configurations of isolated single chains with coil configurations in either -solvent or a dense melt, respectively. Possible consequences for various approaches toward the chemically realistic modeling of polymeric materials are briefly discussed.

Human exposures to arsenic (As) through different pathways (dietary and non-dietary) are considered to be one of the primary worldwide environmental health risks to humans. This study was conducted to investigate the presence of As in soil and vegetable samples collected from agricultural lands located in selected southern districts of Khyber Pakhtunkhwa (KPK) Province, Pakistan. We examined the concentrations of total arsenic (TAs), organic species of As such as monomethylarsonic acid (MMA) and dimethylarsonic acid (DMA), and inorganic species including arsenite (AsIII) and arsenate (AsV) in both soil and vegetable. The data were used to determine several parameters to evaluate human health risk, including bioconcentration factor (BCF) from soil to plant, average daily intake (ADI), health risk index (HRI), incremental lifetime cancer risk (ILTCR), and hazard quotient (HQ). The total As concentration in soil samples of the five districts ranged from 3.0-3.9 mg kg−1, exhibiting minimal variations from site to site. The mean As concentration in edible portions of vegetable samples ranged from 0.03-1.38 mg kg−1. It was observed that As concentrations in 75% of the vegetable samples exceeded the safe maximum allowable limit (0.1 mg kg−1) set by WHO/FAO. The highest value of ADI for As was measured for M. charantia, while the lowest was for A. chinense. The results of this study revealed minimal health risk (HI <1) associated with consumption of vegetables for the local inhabitants. The ILTCR values for inorganic As indicated a minimal potential cancer risk through ingestion of vegetables. In addition, the HQ values for total As were <1, indicating minimal non-cancer risk.

By using tetrathiafulvalene as reducing and doping agents, three‐dimensional (3D) sulfur‐doped graphene hydrogels (SGHs) were facilely prepared in mixed solvents of dimethyl formamide and water. Several investigations reveal that TTF plays a critical role in the formation of such unique 3D architecture, as it not only reduces GO to self‐assembly into 3D structures, but also can be transformed to TTF·+ and TTF2+ as doping agents in the reduction process. The morphology, crystal structure, chemical bonding, elemental composition and porosity of the as‐prepared SGHs have been studied. Benefiting from well‐defined and cross‐linked 3D porous network architectures, the supercapacitors based on the SGHs in KOH electrolyte exhibited a high specific capacitance of 212.5 F·g−1 at 0.3 A·g−1. Furthermore, this capacitance also showed good electrochemical stability and a high degree of reversibility in the repetitive charge/discharge cycling test.

The consideration of the water energy nexus inspires environmental engineers to pursue a more sustainable remediation method for pollution control and resource recovery. In this study, a cost-effective strategy is proposed to enhance the adsorption capacity of bentonite toward environmental phosphate by sequestrating naturally abundant seawater calcium and magnesium. By adopting this method, the adsorption capacity of modified bentonite toward phosphate is enhanced by two orders of magnitude (11.45 vs. 0.11 mg g À1 ). This achievement can be realized as a result of the intercalated seawater Ca 2+ / Mg 2+ to screen the negative charge of aluminum phyllosilicate sheets of bentonite. The results from an additional SEM/EDX analysis and FTIR characterization imply that adsorbed phosphate is strongly associated with the intercalated Ca 2+ /Mg 2+ in a configuration similar to that of hydroxyapatite. Moreover, our results demonstrate that the acquisition of ocean resources would be a promising and green strategy for the perspective of environmental remediation.