Search

It is still challenging to design effective g-C 3 N 4 photocatalysts with high separation efficiency of photo-generated charges and strong visible light absorption. Herein, a simple, template-free and "bottom-up" strategy has been developed to prepare 1D/2D g-C 3 N 4 isotype heterojunction composed of carbon-doped nanowires and ultra-thin nanosheets. The ethanediamine (EE) grafted on melamine ensures the growth of 1D g-C 3 N 4 nanowires with high carbon doping, and the ultra-thin g-C 3 N 4 nanosheets were produced through HCl-assisted hydrothermal strategy. The apparent grain boundary between 2D nanosheets and 1D carbon-doped nanowires manifested the formation of the isotype heterojunction. The built-in electric field provide strong driving force for photogenerated carriers separation. Meanwhile, the doping carbon in g-C 3 N 4 nanowires promotes visible light absorption. As a result, the photocatalytic H 2 evolution activity of 1D/2D g-C 3 N 4 isotype heterojunction is 8.2 time that of the pristine g-C 3 N 4 , and an excellent stability is also obtained. This work provides a promising strategy to construct isotype heterojunction with different morphologies for effective photocatalytic H 2 evolution. The application of 1D/2D g-C 3 N 4 isotype heterojunction as effective and stable photocatalysts for visible-light-driven H 2 production is reported. [Display omitted] • A simple, template-free and "bottom-up" strategy has been developed to prepare 1D/2D g-C 3 N 4 isotype heterojunction. • The ethanediamine grafted on melamine ensures the growth of 1D g-C 3 N 4 nanowires with carbon doping. • The photocatalytic H 2 evolution activity of 1D/2D g-C 3 N 4 isotype heterojunction is 8.2 time that of the pristine g-C 3 N 4. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we present several relaxed inexact projection methods for the split feasibility problem (SFP). Each iteration of the first proposed algorithm consists of a projection onto a halfspace containing the given closed convex set. The algorithm can be implemented easily and its global convergence to the solution can be established under suitable conditions. Moreover,we present some modifications of the relaxed inexact projection method with constant stepsize by adopting Armijo-like search. We furthermore present a variable-step relaxed inexact projection method which does not require the computation of the matrix inverses and the largest eigenvalue of the matrix A T A, and the objective function can decrease sufficiently at each iteration. We show convergence of these modified algorithms under mild conditions. Finally, we perform some numerical experiments, which show the behavior of the algorithms proposed. [Copyright &y& Elsevier]

Abstract: An activated vinyl cyclopropane reacted with substituted benzaldehydes to afford α-methylene γ-butyrolactones in the presence of DABCO·6H2O. This tandem domino process took place in aqueous media, and was presumably initiated with the ring opening of cyclopropane by the nucleophilic addition of DABCO·6H2O. [Copyright &y& Elsevier]

Rhizosphere is a microbiosphere and has quite different chemical, physical and biological properties from bulk soils. A greenhouse experiment was performed to compare the difference of fractionation and bioavailability of trace elements Cr, Ni, Zn, Cu, Pb and Cd between rhizosphere soil and bulk soil. In the meantime, the influence of air-drying on the fractionation and bioavailability was also investigated by using wet soil sample as a control. Soils in a homemade rhizobox were divided into four zones: rhizosphere, near rhizosphere, near bulk soil and bulk soil zones, which was designated as S1, S2, S3 and S4. Elemental speciations were fractionated to water soluble, exchangeable and carbonate bound (B1), Fe–Mn oxide bound (B2), and organic and sulfide bound (B3) by a sequential extraction procedure. Speciation differences were observed for elements Cr, Ni, Zn, Cu, Pb and Cd between the rhizosphere and bulk soils, and between the air-dried and wet soils as well. The concentrations of all six heavy metals in fraction B1 followed the order of S2>S3>S1>S4 and for B2, the order was S2>S3≈S4>S1. For B3, the order was S1>S3≈S4>S2, while for Cd the order was S2>S3≈S4>S1. The air-drying increased elemental concentration in fractions B1 and B2 by 20–50% and decreased in fraction B3 by about 20–100%. Correlation analysis also indicated that the bioavailability correlation coefficient of fraction B1 in rhizosphere wet soil to plants was better than that between either air-dried or nonrhizosphere soils. Therefore, application of rhizosphere wet soils should be recommended in the future study on the speciation analysis of trace elements in soils and bioavailability. [Copyright &y& Elsevier]

Abstract: We presented a Lewis acid-catalyzed nucleophilic ring opening of methylenecyclopropane (MCP) 1,1-diesters with propargyl alcohols. Unlike the proximal-bond cleavage mode observed in cases of unactivated MCPs, the intrinsic characteristic of MCP 1,1-diesters gave a regiospecific distal-bond cleavage under attack of propargyl alcohols as nucleophiles. By combining a subsequent intramolecular Conia-ene reaction, 3,5-dimethylenetetrahydropyrans could be obtained in either a stepwise or a one-pot strategy. [ABSTRACT FROM AUTHOR]

Abstract: A highly regioselective tandem 1,3-dipolar cycloaddition of cyclopropene 1,1-diesters with nitrile oxides was described. This reaction supplied a new method for synthesis of polyfunctionalized isoxazole derivatives in moderate to excellent yields under mild conditions. [Copyright &y& Elsevier]

Abstract: Catalyzed by Lewis acids, donor–acceptor cyclopropane 1,1-diesters reacted with enol silyl ethers to afford 1,6-dicarbonyl compounds in moderate to excellent yields. This supplied a mild carbon–carbon bond-forming method from the ring opening of cyclopropanes. A smooth tandem [3+2] cycloaddition/ring opening process has been clearly proved by an independent experiment. [Copyright &y& Elsevier]

The appearance of 8-oxo-2′-deoxyguanosine (8-oxodG) was examined immunohistochemically using an 8-oxodG-monoclonal antibody in 28 cases of arsenic-related human skin tumors and in 20 cases of arsenic-unrelated human skin cancer to determine if the induction of oxidative stress participates in skin tumorigenesis caused by arsenics. The rate of 8-oxodG-positive was significantly higher in arsenic-related human skin cancer (28 of 28, 100%) than in arsenic-unrelated human skin cancer (3 of 20, 15%, P<0.01 by χ2 test). Moreover, in all the arsenic-related skin samples, 8-oxodG was detected not only in tumor tissues but also in keratosis and normal tissues. These results suggest that the induction of oxidative stress may play an important role in arsenic carcinogenesis. [Copyright &y& Elsevier]

This paper reports a case study on cleaner production of digital control manufactured sand (DMS) and ecological utilization of recycled SP (stone powder) in Hechi-Baise Expressway Project. The novel production system can not only produce high-quality manufactured sand, but also recycle waste stone powder and reduce environmental pollution. Compared with common manufactured sand, the digital control manufactured sand has more reasonable gradation, modified particle shape and regulable stone powder content, which will significantly simplify the ecological application of DMS. The performance of fine aggregate type and stone powder content under several engineering mix proportions is evaluated. The results show that compared with manufactured sand (MS) concrete, the working performance of concrete with DMS is increased by 16.19% on average, and the strength is increased by 7.1% on average, and it has excellent resistance to chloride ion penetration., The application of DMS also reduce the cement and supplementary cementitious materials content of concrete. Recycled SP is comprehensively used in the digital control cleaner production of manufactured sand. The zero discharge of solid waste i.e., waste stone, rubble, dust, and slurry is realized, therefore remarkable economic and ecological benefits are achieved. • The digital control cleaner production realizes the recovery of stone powder. • Digital control manufactured sand has better gradation and particle shape compared with common manufacture sand. • The addition of DMS and recycled SP improves the properties of concrete. • The application of DMS and recycled SP in expressway engineering has achieved high economic and environmental. [ABSTRACT FROM AUTHOR]

Controlling the fibril-formation process of collagen in vitro to fabricate novel biomaterials is a new area in the field of collagen research. This study aimed to determine the effect of ultrasonication on collagen fibril formation and the properties of the resulting collagen gels. Native collagen, extracted from the skin of grass carp, self-assembled under ultrasonic conditions (at different ultrasonic power and duration). The self-assembly kinetics, fibrillar morphology, and physical and cell growth-promoting properties of the collagen gels were analyzed and compared. The results showed that the self-assembly rate of collagen was increased by ultrasonication at the nucleation stage. The resulting fibrils exhibited smaller diameters and D-periodicity lengths than that of the untreated collagen samples ( p < 0.05). The viscoelasticity and textural properties of collagen gels also changed after ultrasonication at the nucleation stage. Texture profile analysis and cell proliferation assays showed that ultrasonication produced softer collagen gel colloids, which were more suitable for cell proliferation than the untreated collagen gels. [ABSTRACT FROM AUTHOR]

Abstract: Total synthesis of natural product (±)-bruguierol A was accomplished in 10-steps and with an overall 16.8% yield. The embedded unique 8-oxabicyclo[3.2.1]octane core skeleton in this natural product was constructed via a novel Sc(OTf)3-catalyzed intramolecular [3+2] cycloaddition of cyclopropane, which was developed recently in this laboratory. This general synthetic strategy can be potentially applied to the synthesis of a broad range of structurally related natural products. [ABSTRACT FROM AUTHOR]

A single microwave extraction procedure was conducted to investigate the bioavailability of rare earth elements (REEs) by using different extractants of 0.05 M EDTA, 0.10 M CH3COOH, 0.10 M HCl, and 0.05 M CaCl2. The experimental conditions of heating time and microwave power were optimized. A microwave power of 60% and extraction time of 30 min were adopted. Compared to the conventional single extraction schemes reported in the literature, the recommended technique shortened the operational time, simplified the experimental task, improved the precision, and obtained consistent results with those obtained by using the conventional methods. In addition, the suggested microwave extraction method has been successfully used to evaluate the bioavailability of REEs in soils. Soil samples collected from 15 sites in China were extracted by four different extractants with microwave ancillary. Extractable REEs from soils were well correlated with REEs contents in shoots of wheat (Troticum aestivum L.) under the greenhouse conditions. The correlation coefficients were 0.6514–0.8996, 0.4522–0.7783, 0.6506–0.8671, 0.4869–0.7014 between the extractable REEs in soils and their concentrations in wheat shoots for the extractants of CaCl2, EDTA, CH3COOH and HCl, respectively. [Copyright &y& Elsevier]

Abstract: A novel tandem reaction of vinylcyclopropane ketone with benzaldehyde has been successfully developed. This provides a new method for the preparation of γ-oxo-hexenone derivatives from easily accessible starting materials. [Copyright &y& Elsevier]

• Poly-generation of rice husk was realized for four end products. • Relative content of phenol was 65.56% in bio-oil. • Syngas contained CO of 56.09 vol%. • Acid washing benefits both pore structure and surface functional groups of biochar. • A low-cost porous carbon with high absorption was obtained after SiO 2 extraction. Rice husk is a widespread agriculture waste in rice-farming country. High silica content in rice husk prevent its efficient utilization. So in this work, concept of poly-generation was introduced to improve its utilization value. This study provided CO-rich syngas, phenol-abundant bio-oil, high-adsorption porous carbon and amorphous SiO 2 as four end products for first time via combination of acid washing and activated carbon catalyst. Specifically, acid washing effectively decreased soluble ash, which altered pyrolysis paths, increased volatiles release and reduced impurities in bio-char. After catalytic pyrolysis, phenol content of 65.56% and CO of 56.09 vol% were detected in bio-oil and syngas from AWRH. For solid products, acid washing benefited both bio-char and silica. A low-cost porous carbon with developed pores and rich surface functional groups was prepared for water absorption. And high purity amorphous SiO 2 was recycled from alkali etching solution. Finally, a green process with no waste emission was proposed. [ABSTRACT FROM AUTHOR]