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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]

Photocatalysis with universality and feasibility has been widely applied to degrade pollutants that mainly exist in gas and liquid systems. However, the photocatalytic degradation of contaminants on solid surfaces is rarely reported. The investigation of the photocatalytic degradation mechanism of pesticide on a solid surface will provide a vital reference for removing pesticide residues on fruit surfaces. Here, we discovered that in situ photocatalytic degradation on solid surface (PDSS) is a moisture dependent process regulated by the interaction between TiO2 and H2O. The interaction mechanism between TiO2 and moisture was revealed by X-ray photoelectron spectroscopy and in situ FT-IR. Meanwhile, we investigated a water layer formed between TiO2 and water on the surface by density functional theory. The photocatalytic degradation process of imidacloprid on the solid surface is proposed. This work explores the H2O impact on photocatalysis in solid surfaces and provides a significant reference for removing pesticide residues in realistic environmental conditions. [ABSTRACT FROM AUTHOR]

A consequent slope, comprising weak planes in the same dip direction along the slope face, is the most dangerous type of rock slope. Herein, a consequent landslide that occurred on May 5, 2018, in Mabian County, Southwest China, was investigated. This landslide occurred in a region with a complex geological background and strong geological activity and is considered a typical consequent landslide. Field investigations and aerial photographic interpretations revealed that the rock mass slipped along the contact surface of the strongly and moderately weathered rock mass, triggered by continuous rainfall. A depth-integrated continuum method was used to study the dynamic process of the landslide. The applicability of the depth-integrated method was verified by comparing the moving boundary of the landslide extracted from a video with the simulation results. The results show that the velocity of the landslide first increased and then decreased from the top to the bottom of the landslide and reached a maximum of 21 m/s in the middle of the landslide. Based on this method, we predicted the potential danger zones and velocity distribution of unstable masses next to the Mabian landslide. On comparing the calculated results of a depth-integrated continuum method with the Scheidegger method, in the case of the Mabian landslide, a reduction factor λ was added to the Scheidegger formula to achieve a modified formula that determines the velocity of such consequent landslides relatively accurately. This work could provide reference for the study of landslide velocity and disaster prevention. [ABSTRACT FROM AUTHOR]

Perchlorate is a low molecular weight highly soluble anion. It occurs naturally in the environment, primarily near potash deposits and in arid regions. The determination of perchlorate in human milk is of interest in vulnerable populations such as infants and pregnant women. In this study, a sensitive and selective isotope dilution ion chromatography/tandem mass spectrometry (ID IC-MS/MS) method was developed and validated for the determination of perchlorate in human milk samples collected from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study. The limit of detection (LOD) was 0.27 µg·kg−1 for human milk. A total of 439 human milk samples were analysed with measurable levels of perchlorate in most of the milk samples, and the mean value was 7.62 ± 32.7 µg·kg−1. This project provided important information related to perchlorate levels in human milk collected across Canada and the extent to which pregnant women and their infants may be exposed to perchlorate. A dietary exposure assessment was also conducted in infants based on the measured values in human milk. The mean perchlorate probable daily intakes (PDIs) for infants consuming human milk were 0.31 ± 0.07 μg/kg bw/day for infants under 1 year and 0.17 ± 0.10 μg/kg bw/day for infants between 1 and 3 years old. None of the estimates exceeded the FAO/WHO provisional maximum tolerable daily intake (PMTDI) of 10 μg/kg bw/day. [ABSTRACT FROM AUTHOR]

Bacterial soft rot caused by Dickeya zeae MS1 (Erwinia chrysanthemi) is one of the most devastating banana diseases worldwide. However, knowledge of the development and ecological interactions of D. zeae MS1 biofilm is limited. Here, we visualized the development and architecture of D. zeae MS1 biofilm using confocal laser scanning microscopy, and we evaluated the ability of D. zeae MS1 to form biofilms under different environmental conditions (carbon sources, temperatures, pH levels and mineral elements) using a microtiter plate assay. We found that the development of D. zeae MS1 biofilm could be categorized into four phases and that mature biofilm consisted of a highly organized architecture of both bacterial cells and a self-produced matrix of extracellular polysaccharides. Furthermore, sucrose was the most suitable carbon source for supporting the growth of biofilm cells and that 32 °C and pH 7.0 were the most favorable of the temperatures and pH levels examined. Meanwhile, the addition of Ca2+, Fe2+, K+ and Na+ enhanced the formation of biofilm in minimal medium cultures, whereas 2.5 mM Cu2+ and Mn2+ was inhibitory. A better understanding of biofilm formation under different environmental parameters will improve our knowledge of the growth kinetics of D. zeae MS1 biofilm. [ABSTRACT FROM AUTHOR]

In order to determine the baseline levels of perchlorate in major brands of baby food, 200 baby food products were collected from retail stores in Ottawa, Canada and analysed for perchlorate in 2010. The seven food groups tested were fruit, juices, vegetables, meat, yogurt, mixed (vegetable mixed with meat) and other (e.g. vegetable mixed with meat and cereal, cheese, egg,). Samples were extracted with a mixture of methanol and 1% acetic acid (4:1, v/v). Determination was conducted by stable isotope dilution ion chromatography tandem mass spectrometry (ID-IC-MS/MS). The complexity of different food matrices required additional method validation. The perchlorate levels in 46 samples were found to be lower than the quantification limit (0.2 ng g−1). The perchlorate levels in the other 154 baby food samples were also low; about 96.7% of the baby foods had perchlorate levels less than 10 ng g−1 (ranged from 0.2 to 22.4 ng g−1, median1.35 ng g−1); only 5 samples had perchlorate levels higher than 10 ng g−1. Dietary exposure to perchlorate from analysed baby food was conservatively estimated to range from 0.007 to 0.121 µg/kg bw/d based on the mean intake for children (1-5 years old). [ABSTRACT FROM AUTHOR]

Fatigue crack damage in the epoxy asphalt concrete pavement of long-span steel bridge deck is still one of the most severe problems even though the fatigue endurance performance has been studied for a long time. In this study, it aimed at exploring the mechanism why the fatigue damage of the epoxy asphalt concrete occurred, as well as finding out the reason why fatigue test results in laboratory were different from those in practical engineering application. A finite element mechanics method was first applied to analyze the maximum strain value of the epoxy asphalt concrete pavement at different load positions, then fatigue performance of the epoxy asphalt concrete was investigated using a four-point bending fatigue testing method, and finally a three-parameter fatigue equation model, which was demonstrated to be feasible and rational, was utilized to determine fatigue endurance limit for the first time. The fatigue damage of the epoxy asphalt concrete occurred in a short time once the strain level with driving load was larger than fatigue endurance limit. In contrast, the fatigue damage did not appear in a long time if the strain level was less than the fatigue endurance limit. It is suggested that the fatigue endurance limit be adopted as a control parameter in the design phase of epoxy asphalt concrete pavement. These findings advance previous design specifications in the world, and could help extending service life of epoxy asphalt concrete pavement of long-span steel bridge deck. [ABSTRACT FROM AUTHOR]

We analyze the statistical properties of the urban public bus networks of two cities (Beijing and Chengdu) in China. To this end, we present a comprehensive survey of the degree distribution, average path length, and clustering of both networks. It is shown that both networks exhibit small world behavior and are hierarchically organized. We also discuss the differences between the statistical properties displayed by the two networks. In addition, we propose a weight distribution approach to study the passenger flow through the public bus networks we considered. A hierarchical structure is observed here also. [ABSTRACT FROM AUTHOR]

Abstract: Tirandamycins are bacterial RNA polymerase inhibitors holding great potential for antibacterial agent design. To elucidate the biosynthetic machinery and generate new derivatives, the tirandamycin biosynthetic gene cluster was cloned and sequenced from marine-derived Streptomyces sp. SCSIO1666. The biosynthetic gene cluster of tirandamycin spans a DNA region of ∼56kb and consists of 15 open reading frames (ORFs) which encode three type I polyketide synthases (TrdAI, AII, AIII), one non-ribosomal peptide synthetase (TrdD), one phosphopantetheinyl transferase (TrdM), one Type II thioesterase (TrdB), one FAD-dependent oxidoreductase (TrdL), one cytochrome P450 monooxygenase (TrdI), three proteins related to resistance and regulations (TrdHJK), and four proteins with unknown function (TrdCEFG). To investigate the roles of the genes played in the biosynthetic machinery, seven genes (trdAI and trdBDFHIK) were inactivated via in frame replacement with an apramycin gene cassette using λ-RED recombination technology. The ΔtrdAI and ΔtrdD mutants targeting the ketosynthase and adenylation domain of TrdAI and TrdD, respectively, abolished the production of tirandamycins, confirming their involvement in the tirandamycin biosynthesis. TrdH showed high homology to LuxR family transcriptional regulatory proteins, disruption of which abolished the production of tirandamycins, indicating that TrdH is a positive regulator for tirandamycin biosynthesis. On the other hand, TrdK showed high homology to TetR-family transcriptional regulatory proteins, disruption of which significantly increased the yields of tirandamycins almost one-fold, implicating that TrdK is a negative regulator for tirandamycin biosynthesis. Disruption of the gene trdI resulted in the accumulation of the intermediate tirandamycin C (3) and a trace amount of new product tirandamycin C2 (5). A model of tirandamycin biosynthesis was proposed based on bioinformatics analyses, gene inactivation experiments and intermediates isolated from the mutants. These findings set the stage for further study of the tirandamycin biosynthetic mechanism and rationally engineer new tirandamycin analogues. [Copyright &y& Elsevier]

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]

Effects of exogenous rare earth elements (REEs) in fertilizer on fraction of heavy metals chromium (Cr), nickel (Ni), zinc (Zn), copper (Cu), lead (Pb), and cadmium (Cd) in 15 Chinese soils and their bioaccumulation by wheat root and shoot were investigated in a greenhouse experiment. Using a three-stage fraction analysis method suggested by the Standard and Testing Program of the European Community (STM), metal fractions were defined as fraction B1 (water soluble, exchangeable, carbonate bound form), B2 (Fe--Mn oxide bound form) and B3 (organic and sulfide bound form). The results revealed that concentrations of elements Cu, Zn, and Pb in fraction B1 increased for all 15 soils in the presence of REEs fertilizer, Cr increased in B1 for 11 soils. Chromium, Cu, Ni, and Zn also universally increased in fraction B3, but no significant changes were found in fraction B2. One-way ANOVA analysis also suggested that the response of heavy metal fractions to REEs fertilizer was significant (P < 0.05) in the order of B3 > B1 > B2. Contrary to the increasing amount of heavy metals in the extractable soil fractions, bioaccumulation of heavy metals in wheat shows no universal increase despite increased Pb in the shoot for 15 soils (P < 0.05) after REEs fertilizer was used. Concentrations of Zn, Pb, and Cd in wheat roots decreased universally, and Cu decreased universally in the shoot after REEs fertilizer was applied. The results of this study indicated that agricultural practice of REEs fertilizers changed the fraction distribution of heavy metals in soils, which in turn affected their availability to plants. In other words, introduction of REEs into soil does interrupt the elemental balance in the environment. [ABSTRACT FROM AUTHOR]

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&ap;S4>S1. For B3, the order was S1>S3&ap;S4>S2, while for Cd the order was S2>S3&ap;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]

• Ill-considered urban planning around Niwan gully may multiply the human and economic losses caused by debris flows. • A depth-integrated model was adopted to determine the hazard zones of debris flows with different recurrence intervals. • The debris flow inundation and evolutionary trajectory are shown to be reasonably comparable with historical debris flows. • This study established a relatively complete system to implement hazard and risk assessment in the study area. The highly geologically active, structurally complex Bailongjiang river basin, Longnan City, Gansu Province hosts many debris-flow gullies. The recent Wenchuan and Jiuzhaigou earthquakes have increased the amount of source material available in these debris flow gullies, and the disturbed nature of the slopes makes them prone to failure under high rainfall, increasing the risk of large-scale debris flows. Moreover, poor urban planning in the region may multiply the human and economic losses caused by debris flows. Therefore, it is necessary to determine the potential hazard zones associated with such debris flows and to implement debris flow hazard and risk assessment. In this paper, Niwan gully is chosen as the study object, as it is characterized by repeated debris flow outbreaks and an ill-considered urban planning at the outlet of the gully. A depth-integrated continuum method is adopted to determine the potential hazard zones of debris flows with different recurrence intervals. The debris flow inundation and evolutionary trajectory are shown to be reasonably comparable with historical debris flows. A two-factor model that couples maximum flow depth with momentum is used to better classify the hazard zones. This study also provides a complete and efficient means to determine the values of debris flow parameters and to implement a hazard and risk assessment based on the solid material reserve method and a probabilistic method. This proposed approach efficiently generated a debris flow risk distribution map that can be used for effective disaster prevention in the Bailongjiang River basin. [ABSTRACT FROM AUTHOR]

In tectonically active steep mountain belts, such as those in west Sichuan in China, frequent landslide disasters can occur during the rainy season. High-locality landslides often initiate with the failure of fractured rock masses or regolith near the ridge of a high and steep slope. Often, these events occur suddenly in the sense that people downslope are caught by surprise. High-locality landslides can be destructive owing to the large momentum and entrainment potential of the moving mass. Increasing attention has been given to these events since the 2008 Wenchuan earthquake. Indeed, slope ridges are particularly susceptible of topographic amplification of the seismic shaking, resulting in mechanical weakening that predisposes them to enhanced weathering and rain-triggered failures years or decades after the mainshock. Risk reduction in such cases must begin with a systematic surveying of the ridges to identify criticalities. Then, quantitative (numerical) approaches must be used to evaluate volumes and describe the movement. Risk assessments can then be produced, and mitigations suggested. Here, we describe the Tonghua landslide in Li County, which is currently in a creeping stage but threatens critical infrastructures and dwellings. We monitored the site for 3 years and identified additional potentially unstable areas before performing physically based modeling and hazard zonation. Our results could be useful in decision-making for risk reduction. [ABSTRACT FROM AUTHOR]

Research of thermally activated delayed fluorescence (TADF) and room‐temperature phosphorescence (RTP) materials is attractive owing to their extensive applications in various fields. However, achieving organic TADF and RTP materials, particularly those with stimulus‐responsiveness and tunability, is highly desirable but challenging and rarely reported. Herein, two easily synthesized organic molecules are reported with abnormal stimulus‐responsive switchable TADF and RTP effects, in which phenothiazine (PTZ) and benzo[b]phenothiazine (BPTZ) based donor−acceptor molecules PTZ‐DBQ and BPTZ‐DBQ show mechanical‐induced TADF in crystalline phase and photo‐responsive RTP in doping poly(methyl methacrylate) (PMMA) films. This is the first time tetracyclic BPTZ has been used as a donor in achieving TADF and RTP materials, and it is found that BPTZ‐DBQ exhibits remarkably better photophysical properties than PTZ‐DBQ. Systematic studies of experimental results and theoretical calculations indicate that the conformational heterogeneity plays an essential role in achieving mechanical‐induced TADF with mechanochromic luminescence (MCL) property. Embedding the organic phosphors into rigid polymer matrices effectively suppresses the molecular motion, thus turning on the RTP emission channel. The conversion of 3O2 to 1O2 under UV irradiation is mainly responsible for the photo‐induced process. These multifunctional luminescent materials have great potential applications in chemical sensors, information encryption, and anti‐counterfeiting. [ABSTRACT FROM AUTHOR]

Manufactured sand (MS) is widely considered as an alternative of the river sand (RS) recently, and to clarify the influence significance and influence mechanism of MS characteristic parameters on its concrete performance is essential to its scientific application. This paper presented series of experimental studies on the influence of MS characteristics on MS concrete performance. Results indicated that the particle shape of MS had little influence on the performance of its concretes, while the stone powder of MS had more remarkable influence on its concrete performance. When the gradations of manufactured sand B (MSB) and RS was adjusted according to Fuller’s curve, the strength of MSB concrete was only lower than that of RS concrete, thus the gradation of MS was not a negative characteristic to concrete strength. The stone powder of MS is most significant factor on its concrete strength and the strength can reach a peak value when the content of stone powder is 7.5%. The MSB concrete has narrower ITZ than that of RS, and only a small amount of AFt crystals is found in the ITZ of MSB, while the stick AFt, AFm and portlandite crystal are enriched at the ITZ of RS concrete, the microstructure of MSB concrete is denser than that of RS. [ABSTRACT FROM AUTHOR]

Review: ca. 100 refs. [ABSTRACT FROM AUTHOR]

An acid-catalyzed domino Meinwald rearrangement of epoxides/intramolecular [3+2] cross-cycloaddition of cyclopropane 1,1-diesters was developed. This supplied a method for the construction of bridged oxa-[ n.2.1] ( n = 3, 4) skeletons. [ABSTRACT FROM AUTHOR]

A novel Lewis acid promoted formal intramolecular [3 + 2] parallel/cross-cycloaddition of cyclopropane 1,1-diesters with allenes has been successfully developed, in which the two CC of allenes were involved respectively. This provides a general and efficient strategy for the construction of structurally diverse [4.3.0]nonane and [3.2.1]octane skeletons. [ABSTRACT FROM AUTHOR]

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]

Dickeya zeae is a globally important bacterial pathogen that has been reported to cause severe soft rot diseases in several essential food crops, including bananas, rice, maize, and potatoes. Carvacrol, a hydrophobic terpene component, is found in aromatic plants of the Labiatae family and various essential oils. However, little work has been done on its antimicrobial potential against D. zeae. This study aimed to evaluate the antimicrobial activity and the functional mechanism of carvacrol against D. zeae. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of carvacrol against D. zeae were 0.1 mg/mL and 0.2 mg/mL, respectively. Carvacrol affected the cell membrane of D. zeae, as revealed by decreased intracellular ATP concentration, nucleic acid leakage, and decreased membrane potential. Scanning electron microscopy (SEM) micrographs confirmed that D. zeae cell membranes were damaged by carvacrol. Furthermore, a significant inhibition of D. zeae swimming motility and biofilm formation was observed following treatments with carvacrol at sub-inhibitory concentrations, indicating a significantly negative effect on these virulence factors. Accordingly, the tissue infection test revealed that carvacrol significantly reduced the pathogenicity of D. zeae. In a pot experiment, inoculated banana seedlings displayed remarkably lesser disease symptoms following treatment with carvacrol, and the control efficiency for banana soft rot was 32.0% at 14 days post-inoculation. To summarize, carvacrol exhibits strong antimicrobial activity against D. zeae and great potential applications in the control of D. zeae-associated crop diseases. [ABSTRACT FROM AUTHOR]

An online monitoring technology of Pu-239 aerosol based on aerosol direct introduction device, membrane desolvation nebuliser and ICP-MS was established for workplaces of reprocessing plants. Briefly, 0.8 l min−1 Pu-239 aerosol from the workplace was introduced into the aerosol direct introduction device where the air was replaced by Argon, and then the aerosol was introduced into the ICP-MS for measurement. To determine the activity of Pu-239 aerosol, 1.10E−3 Bq ml−1 Pu-242 standard solution generated by a membrane desolvation nebuliser was used. The introduction efficiency of the nebuliser was determined by sampling the aerosol generated from the nebuliser with Lead Standard Solution by glass fiber filter, which was (26.82 ± 3.33) %. The mass bias between Pu-239 and Pu-242 for the ICP-MS measurement was determined by Pu-239 and Pu-242 standard solutions generated by the nebuliser, and mass discrimination correction factor for Pu-239/Pu-242 was 0.972 ± 0.010. The limit of detection (LOD) and limit of quantification (LOQ) of this system were calculated according to the ISO 20 899:2018, which were 2.24E−05 Bq m−3 and 7.45E−05 Bq m−3 with 1 min measurement. The main interference which was from U-238 was determined by U-238 standard solution generated by the nebuliser, and the interferences of U-238 to 239 was (8.50 ± 1.05) E−05. According to the counts of U-238 from several workplaces of reprocessing plant where this system was tested, 239 counts rate from the interferences of U-238 of those workplaces were at the same level of the system background counts, which meant that the LOD above was suitable for those places. [ABSTRACT FROM AUTHOR]

Sterculia lanceolata, an important tropical woody plant, has high ornamental and medicinal value. To our knowledge, only brown root disease in this plant has been reported. In Nanning, Guangxi, China, an outbreak of leaf blight disease was observed on S. lanceolata in June 2019, with the leaf infection rate ranging from 80% to 100%. The disease seriously affected the leaves of trees and caused economic loss. Eight isolates were recovered from the infected leaves of different trees, and the pathogenicity was then determined by the methods of mycelial disc and conidial suspension, fulfilling Koch's postulates. According to the morphological and molecular biological characteristics of isolates, the pathogen causing leaf blight on S. lanceolata was identified as Colletotrichum siamense. Accurate identification of the pathogen provides a reliable basis for the control of the disease. [ABSTRACT FROM AUTHOR]

The focus of this paper is on two large sequential landslides which formed a dam and the resulting lake that occurred along the Jinsha River on October 11 and November 3, 2018. About 24 and 9 × 106 m3 of material failed and rushed into the river, respectively. Both landslides totally blocked the river and induced hazard chains. Four multi-temporal unmanned aerial vehicle (UAV)-based high-resolution images and digital elevation models (DEMs) before and after the landslides were obtained and merged. The initial deformation of the two landslides can be clearly captured by optical remote-sensing images and interferometric synthetic aperture radar (InSAR) analysis. The depth-integrated continuum method was adopted to analyze the dynamic process of both landslides, using the same basal friction angle and cohesion. The computational results matched well with field measurements and observations. It is shown that the evaluation of potentially landslide-prone areas by the depth-integrated continuum method is feasible and is able to provide significant information before a possible event. [ABSTRACT FROM AUTHOR]

Highlights • The influence of different mineral admixtures on resistance to simulated seawater was investigated. • The addition of mineral admixtures except of LP can inhibit the expansion of the pastes after 180 d. • FA paste has a good effect on resistance to simulated seawater. • The microstructure of the pastes with mineral admixtures is denser than that of the pure cement paste in simulated seawater. Abstract With the blooming of ocean construction engineering, the influence of seawater on concrete durability draws increasing attentions. This paper investigates the performances of five high performance concrete (HPC) pastes, including pure cement paste, fly ash (FA) paste, limestone powder (LP) paste, ground granulated blast-furnace slag (GGBS) paste and silica fume (SF) paste, soaked in simulated seawater. The results indicate that the addition of FA would improve the strength of paste soaked in simulated seawater compared to pure cement paste from 90 d to 360 d and the order of strength in 360 d was, FA paste > Pure cement paste > LP paste > GGBS paste > SF paste. All mineral admixtures except LP can inhibit the expansion of paste soaked in simulated seawater at later age and the order of expansion rate in 360 d was, LP paste > Pure cement paste > FA paste > GGBS paste > SF paste. The internal structure of pastes soaked in simulated seawater at 360 d mainly contains Ca(OH) 2 , AFt, gypsum, Mg(OH) 2 , C 3 S and C 2 S while the external structure of pastes mainly contains Mg(OH) 2 , CaCO 3 and AFt through the XRD spectra. SEM results proved that the addition of mineral admixtures can make the structure of the pastes denser. [ABSTRACT FROM AUTHOR]

The objective of this study was to explore the endocytosis mechanisms of uranium uptake in HK-2 cells and its toxic effects. Our results demonstrated that uranium exposure impairs redox homeostasis and increases the permeability of the cell membrane and mitochondrial membrane, which may induce cell apoptosis by cytochrome-c leakage. Alkaline phosphatase activity increased after uranium exposure, which may be involved in the process of intracellular mineralisation of uranium, leading to severe cell necrosis. Furthermore, our findings demonstrated that the clathrin-mediated endocytosis process contributed substantially to uranium uptake in HK-2 cells and the total uranium uptake was highly correlated with cell viability, reaching a high correlation coefficient (r = −0.853) according to Pearson correlation analysis. In conclusion, the uptake of uranium into mammalian cells was mainly facilitated by the clathrin-mediated endocytosis pathway and induced dose-dependent cellular toxicity, including redox homeostasis imbalance, membrane injury, cell apoptosis and necrosis. • Uptake of uranium into HK-2 cells was mainly facilitated by clathrin-mediated endocytosis pathway. • Uranium disturbed the antioxidant defense system and induced imbalance of redox homeostasis and impairment of cell membrane. • Uranium induced cell apoptosis at low concentrations, while necrosis increased obviously at high concentrations. • The total uranium uptake was significantly correlated with cell viability with a high negative correlation coefficient (r = −0.853). [ABSTRACT FROM AUTHOR]

Abstract: An efficient synthesis of (−)‐pyrido[3,4‐b]homotropane (PHT) as well as (±)‐PHT has been achieved in 7 steps from conveniently available starting materials. Key transformations involve an efficient construction of the core bridged 9‐aza‐[4.2.1]nonane skeleton via a Sc(OTf)3‐catalyzed intramolecular cross [3+2] cycloaddition (IMCC) followed by Krapcho decarboxylation and Barton reductive decarboxylation. The present work supplies a general and efficient strategy for synthesis of other bridged analogues. [ABSTRACT FROM AUTHOR]

A novel Lewis acid-catalyzed [3+2] intramolecular cross-cycloaddition (IMCC) between aziridine 2,2-diesters and conjugated dienes has been developed. This is the first regiospecific IMCC of intramolecular 1,3-dipolar cycloadditions of azomethine ylides with carbon=carbon double bonds, and supplies a general and efficient strategy for construction of structurally complex and diverse aza-[ n.2.1] skeletons. The [3+2]IMCC could be carried out under mild conditions and in gram scale. More importantly, 3-alkyl-substituted aziridines were also successful. The excellent structural diversity, the facile operation and the versatile post-modifications will support the applications of the [3+2]IMCC in natural products synthesis and drugs discovery. [ABSTRACT FROM AUTHOR]

Aiming to develop efficient and general strategies for construction of complex and diverse polycyclic skeletons, we have successfully developed [4+3]IMPC (intramolecular parallel cycloaddition) of cyclopropane 1,1-diesters with [3]dendralenes. With a combination of the [4+3]IMPC and subsequent [4+ n] cycloadditions, trans-[5.3.0]decane skeleton and its corresponding structurally complex and diverse polycyclic variants could be constructed efficiently. This novel [4+3] cycloaddition reaction mode of donor-acceptor cyclopropanes proceeds as a result of the ring-strain relief of a trans-[3.3.0]octane. We strongly believe that the developed methods will demonstrate potential applications in natural products synthesis and drug discovery. [ABSTRACT FROM AUTHOR]

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]

In contast to the general [4+2] cycloaddition reactions of alkynylcyclopropane ketones reported in the literature, we report herein a Sc(OTf)3-catalyzed formal intermolecular [3+2] cycloaddition reaction of alkynylcyclopropane ketones with electron-rich aromatic aldehydes. 2,3,3,5-Tetrasubstituted tetrahydrofurans were obtained by this method, and the tetrahydrofuran skeleton was diastereoselectively constructed with a 2,5- trans configuration. This is also quite different to the 2,5- cis configuration usually obtained from typical [3+2] cycloaddition reactions of most donor-acceptor cyclopropanes. Additionally, the cycloadducts were subjected to a domino carbopalladation/C-H activation/C-C bond-formation process for the highly efficient construction of polycyclic skeletons. [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]

An abstract of the article "Acid-Catalyzed Domino Meinwald Rearrangement of Epoxides/Intramolecular [3 + 2] Cross-Cycloaddition of Cyclopropane-1,1-dicarboxylates" by W. Zhu and colleagues is presented.

A Lewisacid catalyzed intramolecular [3 + 2] cross cycloadditionof cobalt-alkynylcyclopropane 1,1-diesters with carbonyls has beensuccessfully developed. Together with simple and efficient postcycloadditionsof the cobalt-alkyne moiety, a general and efficient strategy forconstruction of structurally complex and diverse medium-sized skeletonsand related polycycles was supplied successfully. [ABSTRACT FROM AUTHOR]

The article presents information on Trifluoromethanesulfonic acid-catalyzed formal cycloaddition of cyclopropane 1,1-Diesters with Nitriles.

The article presents chemical equations for the article "Lewis Acids Promoted Formal Intramolecular [3 + 2] Parallel and Cross-Cycloadditions of Cyclopropane 1,1-Diesters with Allenes" by Z. Wang and colleagues, published in "Organic Letters" in 2013 issue.

Kohlenstoffbrücken: Die Titelreaktion wurde entwickelt und in der Totalsynthese der tetracyclischen Diterpenoide Phyllocladanol und Phyllocladen verwendet. Die Methode bietet eine effiziente, allgemeine und konzeptionell neue Strategie zum Aufbau strukturell komplexer [n.2.1]Carbocyclen (siehe Schema). [ABSTRACT FROM AUTHOR]

Carbon bridges: The title reaction has been successfully developed, and applied to the total synthesis of the tetracyclic diterpenoids phyllocladanol and phyllocladene. The method provides an efficient, general, and conceptually new strategy for the construction of structurally complex and diverse [n.2.1] carbocyclic skeletons (see scheme). [ABSTRACT FROM AUTHOR]

This article covers challenges and trends in the determination of some major food chemical contaminants and allergens, which-among others-are being monitored by Health Canada's Food Directorate and for which background levels in food and human exposure are being analyzed and calculated. Eleven different contaminants/contaminant groups and allergens have been selected for detailed discussion in this paper. They occur in foods as a result of: use as a food additive or ingredient; processing-induced reactions; food packaging migration; deliberate adulteration; and/or presence as a chemical contaminant or natural toxin in the environment. Examples include acrylamide as a food-processing-induced contaminant, bisphenol A as a food packaging-derived chemical, melamine and related compounds as food adulterants and persistent organic pollutants, and perchlorate as an environmental contaminant. Ochratoxin A, fumonisins, and paralytic shellfish poisoning toxins are examples of naturally occurring toxins whereas sulfites, peanuts, and milk exemplify common allergenic food additives/ingredients. To deal with the increasing number of sample matrices and analytes of interest, two analytical approaches have become increasingly prevalent. The first has been the development of rapid screening methods for a variety of analytes based on immunochemical techniques, utilizing ELISA or surface plasmon resonance technology. The second is the development of highly sophisticated multi-analyte methods based on liquid chromatography coupled with multiple-stage mass spectrometry for identification and simultaneous quantification of a wide range of contaminants, often with much less requirement for tedious cleanup procedures. Whereas rapid screening methods enable testing of large numbers of samples, the multi analyte mass spectrometric methods enable full quantification with confirmation of the analytes of interest. Both approaches are useful when gathering surveillance data to determine occurrence and background levels of both recognized and newly identified contaminants in foods in order to estimate human daily intake for health risk assessment. [ABSTRACT FROM AUTHOR]

Two new cytochalasins, 18-deoxycytochalasin Q ( 1) and 21- O-deacetylcytochalasin Q ( 2), together with four known analogues, cytochalasin Q ( 3), 19,20-epoxycytochalasin Q ( 4), 21- O-deacetyl-19,20-epoxycytochalasin Q ( 5), and cytochalasin D ( 6), were isolated from the fungus Xylaria sp. SCSIO156 originated from the South China Sea marine sediment. The structures of 1 and 2 were elucidated by MS and 1D- and 2D-NMR data analyses, and comparison with known compounds. The known compounds 3- 6 were identified by comparison of their MS and NMR data with those reported in the literature. In the in vitro antitumor assay, compounds 2- 6 showed mild cytotoxicity against three tumor cell lines (MCF-7, SF-268, and NCI-H460). [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]

A novel Lewis acid‐catalyzed [3+2] intramolecular cross‐cycloaddition (IMCC) between aziridine 2,2‐diesters and conjugated dienes has been developed, which supplies a general and efficient strategy for construction of structurally complex and diverse aza‐[n.2.1] skeletons. The excellent structural diversity, the facile operation and the versatile post‐modifications will support the applications of the [3+2]IMCC in natural product synthesis and drug discovery. “Three begets all things of the world” comes from “Daodejing”, an immortal classic composed by Laozi, a great philosopher and thinker of ancient China. In this chemistry, the three‐membered aziridine means the “three” which begets the diversity and complexity by the IMCC strategy. For the full story see the Communication by Z. Wang et al. on page 17862 ff. [ABSTRACT FROM AUTHOR]