Chromium is a potentially toxic and carcinogenic metal originating from natural processes and anthropogenic activities such as the iron steel, electroplating and leather industries. Therefore, ...chromium should be removed from wastewater to avoid environmental pollution and to recycle chromium in the context of the future circular economy. Here we briefly review aqueous Cr species, their toxicity and methods to remove Cr such as membrane filtration, chemical precipitation, ion exchange, adsorption electrocoagulation, electrochemical reduction, electrodialysis, electrodeionization, photocatalysis and nanotechnology.
Cyclobutenones, four‐membered ketones bearing an unsaturated carbon–carbon double bond, and their structural sibling benzocyclobutenones, possess unique reactivity. Owing to their inherent high ring ...strain, such structures readily undergo ring opening under a variety of conditions, including thermolysis, photolysis, and transition metal catalysis, to afford reactive intermediates that can be trapped with nucleophiles, dienophiles, and unsaturated bonds. Their electron‐deficient enone moieties are good electrophiles for facile nucleophilic addition. Such properties render cyclobutenones versatile synthons, serving as excellent coupling partners in a vast array of synthetically valuable transformations.
Square routes: Cyclobutenones and their structural sibling benzocyclobutenones possess unique reactivity due to the ring strain and electron‐deficient enone moieties. Such properties render them serving as excellent coupling partners in a variety of synthetically valuable transformations.
A quantitative method was established to determine the well-known endocrine disruptor bisphenol A (BPA) in barreled drinking water. Samples were pretreated by solid phase extraction (SPE), and then ...analyzed by liquid chromatography-mass spectrometry (LC-MS). Working standard solutions were obtained by pretreatment of a series of aqueous standard solutions over the concentration range of 122.9-1190.7 ng L
−1
. The linear calibration curve was Y = 69.4X + 2206.2 with the correlation coefficient (R
2
) of 0.9929. The average recoveries from spiked samples were more than 91.6%. The relative standard deviations (n = 6) were less than 9.6%. The method allowed the detection of 7.0 ng L
−1
BPA in barreled drinking water. Typical barreled drinking water products in the market were detected. As results, thirty-five of fifty-two commercial samples were found to contain BPA with a maximum concentration of 898.7 ng L
−1
. The occurrence of BPA in barreled drinking water may be due to the pollution of raw water, the inefficiency of purification processes and the migration of BPA from barrels. The daily exposure of adults to BPA through drinking barreled drinking water is far below the current human tolerable daily intake (TDI) set by European Food Safety Authority (EFSA).
Reliability-based design optimization (RBDO) has been widely implemented for engineering design optimization when considering the uncertainty. The single loop approaches (SLA) are highly efficient ...but is prone to converge with inappropriate results for highly nonlinear probabilistic constraints. In this paper, a novel RBDO algorithm is proposed based on single loop approach and the enhanced chaos control method, named as enhanced single-loop method (ESM). The performance of SLA is enhanced using an adaptive inverse reliability method with limited number of iterations. The adaptive step size is computed based on a merit function which is computed using the results of the new and previous iterations. The iterations of the probabilistic constraints of RBDO models are manually controlled in the range from 1 to 10 in ESM. The efficiency and accuracy of the ESM are compared through four nonlinear RBDO problems with complex constraints, including a nonlinear mathematical problem, two engineering problems and a practical complex stiffened panel example with complex buckling constraint for aircraft design. Results illustrate that the proposed ESM is more efficient and robust than the performance measure approach and reliability index approach for RBDO problems.
Liquid metals (LMs) are receiving growing interest in modern technologies for their various advantages. This work reports using elemental sulfur to achieve nanodispersed liquid metals in bulk ...polymers for multifunctional LM‐based materials. Ring‐opening polymerization and inverse vulcanization of elemental sulfur provide many polysulfide loops and thiol groups as effective binding ligands that enable extraordinarily uniform dispersion of liquid metals (≈1 µm) in bulk matrix and improve the mechanical performance of the materials. Interestingly, the liquid‐metal‐embedded sulfur polymer (LMESP) materials exhibit excellent thermal‐/solvent‐processability and recyclability. The uniform dispersion leads to phenomenal electrical conductivity of the LMESP at a low volume percentage of LM (30 vol%), overcoming the issue of nonconductivity typically seen in insulated LM–polymer blends. Additionally, the LMESP shows resistive sensitivity toward external pressure. Furthermore, the LMESP materials exhibit an excellent self‐healing ability under mild conditions via the dynamic bonds between polysulfide loops/thiol groups and liquid metals. This work clearly offers a new platform to design liquid metals and can push them for broad applications.
Elemental sulfur is used to achieve nanodispersed liquid metals (LMs) in bulk polymers for multifunctional LM‐based materials. The resulting liquid‐metal‐embedded sulfur polymer shows unique features in different aspects, including superior dispersion of liquid metals, excellent thermal‐/solvent‐processability and recyclability, improved mechanical performance, phenomenal electrical conductivity, resistive pressure‐sensitivity, and remarkable self‐healing under mild conditions.
A tunable rhodium‐catalyzed intramolecular alkyne insertion reaction proceeding through the CC cleavage of benzocyclobutenones is described. Selective formation of either the direct or ...decarbonylative insertion product can be controlled by using different catalytic systems. A variety of fused β‐naphthol and indene scaffolds were obtained in good yields with high functional group tolerance. This work illustrates a divergent approach to synthesize fused‐ring systems by CC activation/functionalization.
Cat. in control: A tunable rhodium‐catalyzed intramolecular alkyne insertion reaction proceeding through CC cleavage of benzocyclobutenones is described. Selective formation of either the direct or decarbonylative insertion product can be controlled by using different catalytic systems. A variety of fused β‐naphthol and indene scaffolds were obtained in good yields with high functional‐group tolerance.
•Enriched self-adjusted PMA is developed to improve drawbacks of nonlinear engineering RBDO.•A novel merit function is proposed to adjust the modified search direction of ESMV using PMA.•The ...convergence performances of proposed PMA are illustrated with particular complex engineering aircraft stiffened panel.•Enriched self-adjusted mean value improves the convergence performances of the RBDO-based PMA.
For reliability-based design optimization (RBDO) of practical structural/mechanical problems under highly nonlinear constraints, it is an important characteristic of the performance measure approach (PMA) to show robustness and high convergence rate. In this study, self-adjusted mean value is used in the PMA iterative formula to improve the robustness and efficiency of the RBDO-based PMA for nonlinear engineering problems based on dynamic search direction. A novel merit function is applied to adjust the modified search direction in the enriched self-adjusted mean value (ESMV) method, which can control the instability and value of the step size for highly nonlinear probabilistic constraints in RBDO problems. The convergence performance of the enriched self-adjusted PMA is illustrated using four nonlinear engineering problems. In particular, a complex engineering example of aircraft stiffened panel is used to compare the RBDO results of different reliability methods. The results demonstrate that the proposed self-adjusted steepest descent search direction can improve the computational efficiency and robustness of the PMA compared to existing modified reliability methods for nonlinear RBDO problems.
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