Search

Chlorinated polyethylene （CPE) flame retardant composites were prepared with CPE as the matrix material and sepiolite as flame retardant, and the effects of the addition amount of sepiolite on cu-ring characteristics, physical and mechanical properties, and flame retardance were studied. The results showed that with the increase in the addition amount of sepiolite, tensile strength, tear strength, modulus at 100%, modulus at 300%, and Shore A hardness of the composites increased significantly; the addition of sepiolite improved limiting oxygen index of the CPE flame retardant composites, reduced the maximum heat release rate and total heat release during combustion of the composites, prolonged the ignition time of the composites, reduced the absolute content of carbon monoxide and carbon dioxode, and decreased the smoke emission.

Two-dimensional (2D) hybrid perovskite sandwiched between two long-chain organic layers is an emerging class of low-cost semiconductor materials with unique optical properties and improved moisture stability. Unlike conventional semiconductors, ion migration in perovskite is a unique phenomenon possibly responsible for long carrier lifetime, current-voltage hysteresis, and low-frequency giant dielectric response. While there are many studies of ion migration in bulk hybrid perovskite, not much is known for its 2D counterparts, especially for ion migration induced by light excitation. Here, we construct an exfoliated 2D perovskite/carbon nanotube (CNT) heterostructure field effect transistor (FET), not only to demonstrate its potential in photomemory applications, but also to study the light induced ion migration mechanisms. We show that the FET I-V characteristic curve can be regulated by light and shows two opposite trends under different CNT oxygen doping conditions. Our temperature-dependent study indicates that the change in the I-V curve is probably caused by ion redistribution in the 2D hybrid perovskite. The first principle calculation shows the reduction of the migration barrier of I vacancy under light excitation. The device simulation shows that the increase of 2D hybrid perovskite dielectric constant (enabled by the increased ion migration) can change the I-V curve in the trends observed experimentally. Finally, the so synthesized FET shows the multilevel photomemory function. Our work shows that not only we could understand the unique ion migration behavior in 2D hybrid perovskite, it might also be used for many future memory function related applications not realizable in traditional semiconductors.

Background:Reynoutria multiflora (Thunb.) Moldenke (PM) is a widely-used medicinal plant in China, whose root and stem are included in the Chinese Pharmacopoeia as Polygoni Multiflori Radix (RPM), Polygoni Multiflori Radix Preparata (PMP), and Polygoni Multiflori Caulis (PMC). The hepatotoxicity of RPM and PMP is concerned by the public, while the risk of PMC is ignored.Purpose: Here, we investigate the potential risks for PMC-induced liver injury from clinical, chemical, and animal features.Study design: First, we analyzed the 12-month usage of RPM, PMP, and PMC in Longhua Hospital. Second, we determined the contents of gallic acid, cis-2,3,5,4′-tetrahydroxy-stilbene-2-O-β-D-glucoside (cis-SG), trans-2,3,5,4′-tetrahydroxy-stilbene-2-O-β-D-glucoside (trans-SG), emodin-8-O-β-D-glucoside (EG), physcion-8-O-β-D-glucoside (PG), emodin, and physcion in the water extracts from 15 batches of RPM, PMP, and PMC. Third, we probed the hepatotoxic effect of RPM, PMP, and PMC in mice and explored the mechanism of cis-SG and trans-SG causing the liver injury at the dosages based on our results from the first and second parts.Results: PMC had nearly five times the amount of usage in both outpatient prescriptions and inpatient orders than RPM and PMP. Overall, 68% dosage of PMC was 30 g. The contents of cis-SG, trans-SG, and emodin in PMC water extracts were significantly lower than those in RPM and PMP water extracts. PMC induced milder idiosyncratic liver injury for its lower content of cis-SG and trans-SG than its root counterparts.Conclusion: The potential risks for PMC-induced liver injury should be fully aware of.

Larvae of Melolonthinae (white grubs) are usually considered as serious pests for some of them attacking plant roots and causing great losses of agriculture and forestry. However, not all the white grubs are pest species. In this study, the adult Apogonia cupreoviridis were observed to feed on gramineous grasses and fallen ginkgo leaves, while their larvae were frequently collected in the lawn. The larvae were reared in the laboratory and observed using scanning electron microscopy. The larvae have the plegmatia expanded in the middle; distal antennomere with an apical process bearing one bifurcated sensilla and nine sensilla basiconica on the apex; the palidia are V‐shaped and each palidium bearing five to nine pali. The V‐shaped palidia are found in the known larvae of Diplotaxini, as to genera Apogonia and Liogenys. [ABSTRACT FROM AUTHOR]

The problem‐project‐oriented STEM education plays a significant role in training students' ability of innovation. Although the conceive‐design‐implement‐operate (CDIO) approach and computational thinking (CT) are hot topics in recent decades, there are still two deficiencies: the CDIO approach and CT are discussed separately and a general framework of coping with complex STEM problems in system modeling and simulation is missing. In this paper, a collaborative strategy based on the CDIO and CT is proposed for solving complex STEM problems in system modeling and simulation with a general framework, in which the CDIO is about "how to do," CT is about "how to think," and the project means "what to do." As an illustration, the problem of solving the period of mathematical pendulum is discussed in detail. The most challenging task involved in the problem is to compute the complete elliptic integral of the first kind (CEI‐1). In the philosophy of STEM education, all problems have more than one solution. For computing the CEI‐1, four methods are discussed with a top‐down strategy, which includes the infinite series method, arithmetic‐geometric mean method, Gauss–Chebyshev method, and Gauss‐Legendre method. The algorithms involved can be utilized for R & D projects of interest and be reused according to the requirements encountered. The general framework for solving complex STEM problems in system modeling and simulation is worth recommending to college students and instructors. [ABSTRACT FROM AUTHOR]

The advent of biotechnology has expedited the understanding of the biochemistry of deoxyribonucleic acids (DNA). In the past, DNA are thought to be present only in cell nucleus as bearers of the genetic code. With the identification of extracellular DNA in circulating body fluids, DNA are now utilized, at least experimentally, for diagnosis and treatment of diseases. Extracellular DNA of host origin trigger immune responses, and are closely linked to autoimmune disease, cancer‐related inflammation, bacteria adhesion and thrombosis. Recent advancements in DNA nanotechnology have led to the development of a series of DNA‐based materials for treating diseases because of their structural programmability. Current discussions on biosafety and immunogenicity of artificial DNA materials are insufficient. This issue severely restricts the clinical translation of these novel biotechnologies. The present review attempts to bridge the gap between natural extracellular DNA and their derivatives, DNA‐based materials. The pathological attributes of endogenous extracellular DNA motivate the design of targeting DNA materials. In addition, the fate of exogenous DNA in the host inspires the optimization of DNA materials in reducing immune rejection. These bioinspired strategies provide the blueprint for utilizing DNA materials in the management of diseases that are currently challenging to diagnose or treat. [ABSTRACT FROM AUTHOR]

Well-defined polycarbonate diol was successfully synthesized through a strategy using a combination of organocatalyst and water. Such strategy was less developed in organocatalyzed polymerization and frequently regarded as side reactions. Herein, one-component phosphonium borane Lewis pairs PB1–PB8 were successfully applied in the copolymerization of CO2 and cyclohexene oxide (CHO) to generate poly(CHO-alt-CO2) carbonate (PCHC). Parameters of linker length and counter anion effects on the catalyst activity were investigated. It was found that Lewis pair PB3 served as a dual initiator and catalyst in the copolymerization of CHO and CO2 with or without the presence of water. In contrast, Lewis pair PB8 can serve as a true catalyst for the preparation of well-defined α,ω)-hydroxyl PCHC diols. This was achieved by introducing a labile CF3COO group as counter anion through anion exchange reaction while water molecules acted as chain transfer agents. The function of trifluoroacetate group in the polymerization process was investigated in detail and possible mechanism was proposed. Upon changing the amount of water and catalyst loading, PCHC diols with varied molecular weight (1.5 kg/mol to 7.5 kg/mol), low dispersities (Ð<1.2) and carbonate content (>99%) could be easily obtained. The low molecular weight PCHC diol was used as a bifunctional macroinitiator for the ring-opening polymerization of L-lactide (LLA) to afford ABA triblock copolymer in one-pot synthesis. [ABSTRACT FROM AUTHOR]