192 research outputs found

    Characteristics of coastline changes in mainland China since the early 1940s

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    Based on multi-temporal topographic maps, remote sensing images and field surveys covering the entire coastal zone of mainland China, the coastlines of six periods since the early 1940s were extracted. Coastline changes over the last 70 years were then analyzed in terms of coastline structure, coastline fractals, coastline change rates, land-sea patterns, and bay areas. The results showed that mainland coastline structure changed dramatically, and due to the significant coastline artificialization mainly driven by sea reclamation and coastal engineering, the remaining natural coastline merely accounts for less than one third at present. Coastline fractal dimension represented an overall spatial pattern of "north < entirety < south"; however, the discrepancy between the north and south coast was apparently narrowed due to dramatic coastline artificialization of northern China which in turn altered the whole pattern. Patterns and processes of land-sea interchange along the mainland coast were complex and varied spatially and temporally, with over 68% advancing toward sea and 22% retreating toward land. The net growth of land area was nearly 14.2 x10(3) km(2) with an average growth rate of 202.82 km(2) a(-1); and coast retreat was characterized by area decrease of 93 bays with a magnitude of 10.1 x10(3) km(2) and an average shrinking rate up to 18.19% or an average shrinking speed up to 144.20 km(2) a(-1), among which the total area of Bohai shrunk by 7.06%, with an average annual loss amounting to 82 km(2). The dramatic coastline changes along mainland China have brought about kinds of challenges to the coastal environment, therefore the integrated management, effective environment protection and sustainable utilization of coastlines is urgent

    Understanding large plastic deformation of SiC nanowires at room temperature

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    Tensile behaviors of SiC [111] nanowires with various possible microstructures have been investigated by molecular-dynamics simulations. The results show that the large plastic deformation in these nanowires is induced by the anti-parallel sliding of 3C grains along an ultra- thin intergranular amorphous film parallel to the (11¯1) plane and inclined at an angle of 19.47◦ with respect to the nanowire axis. The resulting large plastic deformation of SiC nanowires at room temperature is attributed to the stretching, breaking and re-forming of Si–C bonds in the intergranular amorphous film, which is also evident from the sawtooth jumps in the stress-strain response

    Effects of cultivation years on effective constituent content of Fritillaria pallidiflora Schernk

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    Fritillaria pallidiflora Schrenk has been treasured in traditional classic medicine as an antitussive, antiasthmatic and expectorant for hundreds of years. With gradually decreasing wild F. pallidiflora resources, the herb can no longer satisfy the demand. Artificial cultivation is one of the most effective ways to solve the contradiction between supply and demand in the medicinal material market. During the growth of Rhizomes medicinal plants, root biomass and active ingredient content showed dynamic accumulated variation with increasing cultivation years. Up to now, hardly any attempts have been made to investigate the relationship between quality and cultivation years of F. pallidiflora. Therefore, in this paper, we determined the optimum harvesting time by comparing biomass and biological characteristics of F. pallidiflora at different cultivation times. High-performance liquid chromatography with evaporative light scattering detection and phenol-sulfuric acid visible spectrophotometry was performed to determine imperialine and polysaccharide content of F. pallidiflora bulbs. From year 1 to 6 of cultivation, we observed an upward trend in plant height, diameter and dry weight of F. pallidiflora, while water content decreased. Plant height and dry weight increased remarkably during the fourth year of cultivation. The content of imperialine and polysaccharide of F. pallidiflora bulbs, on the other hand, showed an upward trend from year 1 to 3, after which it decreased from year 3 to 6. By comparing plant growth, biomass development and the accumulation of imperialine and polysaccharide, the best harvesting time of F. pallidiflora was determined to be after 4 years of cultivation. Our results showed that it is possible to establish a safe, effective, stable and controllable production process, which could play an important role in achieving sustainable utilization of F. pallidiflora resources.Fritillaria pallidiflora Schrenk has been treasured in traditional classic medicine as an antitussive, antiasthmatic and expectorant for hundreds of years. With gradually decreasing wild F. pallidiflora resources, the herb can no longer satisfy the demand. Artificial cultivation is one of the most effective ways to solve the contradiction between supply and demand in the medicinal material market. During the growth of Rhizomes medicinal plants, root biomass and active ingredient content showed dynamic accumulated variation with increasing cultivation years. Up to now, hardly any attempts have been made to investigate the relationship between quality and cultivation years of F. pallidiflora. Therefore, in this paper, we determined the optimum harvesting time by comparing biomass and biological characteristics of F. pallidiflora at different cultivation times. High-performance liquid chromatography with evaporative light scattering detection and phenol-sulfuric acid visible spectrophotometry was performed to determine imperialine and polysaccharide content of F. pallidiflora bulbs. From year 1 to 6 of cultivation, we observed an upward trend in plant height, diameter and dry weight of F. pallidiflora, while water content decreased. Plant height and dry weight increased remarkably during the fourth year of cultivation. The content of imperialine and polysaccharide of F. pallidiflora bulbs, on the other hand, showed an upward trend from year 1 to 3, after which it decreased from year 3 to 6. By comparing plant growth, biomass development and the accumulation of imperialine and polysaccharide, the best harvesting time of F. pallidiflora was determined to be after 4 years of cultivation. Our results showed that it is possible to establish a safe, effective, stable and controllable production process, which could play an important role in achieving sustainable utilization of F. pallidiflora resources

    An integrated proteomic and metabolomic study on the gender-specific responses of mussels Mytilus galloprovincialis to tetrabromobisphenol A (TBBPA)

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    Tetrabromobisphenol A (TBBPA), accounting for the largest production of brominated flame-retardants (BFRs) along the Laizhou Bay in China, is of great concern due to its diverse toxicities. In this study, we focused on the gender-specific responses of TBBPA in mussel Mytilus galloprovincialis using an integrated proteomic and metabolomic approach. After exposure of TBBPA (10 mu g L-1) for one month, a total of 9 metabolites and 67 proteins were altered in mussel gills from exposed group. The significant changes of metabolites in female mussel gills from exposed group exhibited the disturbances in energy metabolism and osmotic regulation, while in male samples only be found the variation of metabolites related to osmotic regulation. iTRAQ-based proteomic analysis showed biological differences between male and female mussel gills from solvent control group. The higher levels of proteins related to primary and energy metabolism and defense mechanisms in male mussel gills meant a greater anti-stress capability of male mussels. Further analysis revealed that TBBPA exposure affected multiple biological processes consisting of production and development, material and energy metabolism, signal transduction, gene expression, defense mechanisms and apoptosis in both male and female mussels with different mechanisms. Specially, the responsive proteins of TBBPA in male mussels signified higher tolerance limits than those in female individuals, which was consistent with the biological differences between male and female mussel gills from solvent control group. This work suggested that the gender differences should be considered in ecotoxicology. (C) 2015 Elsevier Ltd. All rights reserved

    A metabolomic study on the biological effects of metal pollutions in oysters Crassostrea sikamea

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    Metal pollution has become a great threat to organisms in the estuaries in South China. In the present study, the oysters Crassostrea sikamea were collected from one clean (Jiuzhen) and five metal polluted sites (Baijiao, Fugong, Gongqian, Jinshan and Songyu). The tissue metal concentrations in oysters indicated that the five metal sites were polluted by several metals, including Cr, Ni, Co, Cu, Zn, Ag, Cd and Pb with different patterns. Especially, Cu and Zn were the major contaminants in Baijiao, Fugong and Jinshan sites. The metabolic responses in oysters C. sikamea indicated that the metal pollutions in BJ, FG, JS and SY sites induced disturbances in osmotic regulation and energy metabolism via different metabolic pathways. However, the metal pollution in GQsite mainly influenced the osmotic regulation in the oysters C sikamea. This study demonstrates that NMR-based metabolomics is useful to characterize metabolic responses induced by metal pollution. (C) 2015 Elsevier Ltd. All rights reserved

    c-axis preferential orientation of hydroxyapatite accounts for the high wear resistance of the teeth of black carp (Mylopharyngodon piceus)

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    Biological armors such as mollusk shells have long been recognized and studied for their values in inspiring novel designs of engineering materials with higher toughness and strength. However, no material is invincible and biological armors also have their rivals. In this paper, our attention is focused on the teeth of black carp (Mylopharyngodon piceus) which is a predator of shelled mollusks like snails and mussels. Nanoscratching test on the enameloid, the outermost layer of the teeth, indicates that the natural occlusal surface (OS) has much higher wear resistance compared to the other sections. Subsequent X-ray diffraction analysis reveals that the hydroxyapatite (HAp) crystallites in the vicinity of OS possess c-axis preferential orientation. The superior wear resistance of black carp teeth is attributed to the c-axis preferential orientation of HAp near the OS since the (001) surface of HAp crystal, which is perpendicular to the c-axis, exhibits much better wear resistance compared to the other surfaces as demonstrated by the molecular dynamics simulation. Our results not only shed light on the origin of the good wear resistance exhibited by the black carp teeth but are of great value to the design of engineering materials with better abrasion resistance

    Persistence Parameter: a Reliable Measurement for Behavioral Responses of Medaka (Oryzias latipes) to Environmental Stress

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    Online monitoring systems provided a significant evidence for feasibility of the stepwise behavioral response model in detecting the effects of organophosphorus pesticides on movements of medaka (Oryzias latipes), being able to determine the state of indicator organisms, &quot;no effect,&quot; &quot;stimulation,&quot; &quot;acclimation,&quot; &quot;adjustment (readjustment),&quot; and &quot;toxic effect.&quot; Though the stepwise behavioral response model postulated that an organism displays a time-dependent sequence of compensatory stepwise behavioral response during exposure to pollutants above their respective thresholds of resistance, it was still a conceptual model based on tendency only in analysis. In this study, the phenomenon of bacterial persistence was used to interpret the relationship between the stepwise behavioral response model and the environmental stress caused by both exposure time and different treatments. Quantitative measurements of the stepwise behavioral response model led to a simple mathematical description of the threshold switch, which evaluated the effects of environmental stress on behavioral responses to decide the tendency. The adjustment ability correlated to &quot;persisters (p)&quot; is very important for test individuals to overcome the &quot;threshold&quot; from the outside environmental stress. The computational modeling results suggested that &quot;persister (p),&quot; as described in the general equations of bacterial persistence model in changing environments, illustrated behavior acclimation and adjustment (or readjustment) clearly. Consequently, the persistence parameter, p, was critical in addressing for medaka to be adapted to fluctuating environments under different environmental stress

    A molecular imprinting-based turn-on Ratiometric fluorescence sensor for highly selective and sensitive detection of 2,4-dichlorophenoxyacetic acid (2,4-D)

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    A novel molecular imprinting-based turn-on ratiometric fluorescence sensor was constructed via a facile sol-gel polymerization for detection of 2,4-dichlorophenoxyacetic acid (2,4-D) on the basis of photo induced electron transfer (PET) by using nitrobenzoxadiazole (NBD) as detection signal source and quantum dots (QDs) as reference signal source. With the presence and increase of 2,4-D, the amine groups on the surface of QDs@SiO2 could bind with 2,4-D and thereby the NBD fluorescence intensities could be significantly enhanced since the PET process was inhibited, while the QDs maintained constant intensities. Accordingly, the ratio of the dual-emission intensities of green NBD and red QDs could be utilized for turn-on fluorescent detection of 2,4-D, along with continuous color changes from orange-red to green readily observed by the naked eye. The as-prepared fluorescence sensor obtained high sensitivity with a low detection limit of 0.14 mu M within 5 min, and distinguished recognition selectivity for 2,4-D over its analogs. Moreover, the sensor was successfully applied to determine 2,4-D in real water samples, and high recoveries at three spiking levels of 2,4-D ranged from 95.0% to 110.1% with precisions below 4.5%. The simple, rapid and reliable visual sensing strategy would not only provide potential applications for high selective ultratrace analysis of complicated matrices, but also greatly enrich the research connotations of molecularly imprinted sensors. (C) 2016 Elsevier B.V. All rights reserved

    Pan-cancer analysis of whole genomes

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    Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe
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