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  • 1
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    Experimental and calculation study on overtopping of framed seawall (2018)
    Institute of Physics (IOP)
    Details
    Publication Date: 2018-11-06
    Description: In recent years, more and more seawalls have been used in tidal areas along coastal areas. The frame type seawall has the advantages of no water occupation, land saving and light weight. It is a difficult problem to determine the overtopping and the elevation of the embankment. In this paper, a physical model test was carried out to measure the average overtopping of a framed seawall at the design frequency of wave height, and the average overtopping was calculated by using the theoretical formula. The results of physical model test and theoretical calculation were compared and analyzed. The results showed that the theoretical formula was 6 to 20% larger than that of the physical model test. Finally, the theoretical formula was proposed to predict the wave overtopping of frame seawall, which met the design requirements and provided a basis for determining the height of the top of the seawall. At the same time, the physical model test showed that the anti-arc cantilever wave abso...
    Print ISSN: 1755-1307
    Electronic ISSN: 1755-1315
    Topics: Geography , Geosciences , Physics
    Published by Institute of Physics (IOP)
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  • 2
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    Lower-Crustal Magmatic Hornblendite in North China Craton: Insight into the Genesis of Porphyry Cu Deposits (2015)
    Society of Economic Geologists (SEG)
    Details
    Publication Date: 2015-09-23
    Description: Genesis of porphyry Cu deposits remains controversial. A common view suggests that the efficient partitioning of Cu into a fluid exsolved from a calc-alkaline magma with normal Cu but elevated S concentrations is critical to ore formation. However, this view was recently challenged by two new ideas, which emphasize that the formation of porphyry Cu deposits requires anomalously Cu rich sources of either a mantle domain or intracrustal magmatic cumulate. Here we report data on an intracrustal magmatic hornblendite, genetically associated with the large Mujicun porphyry Cu deposit in North China craton. Petrographic observations, geochemical data, and P-T calculations indicate that the hornblendite formed at a depth of ~28 km by amphibole accumulation from a basaltic magma. These cumulates, despite containing traces of Cu-bearing sulfides, have Cu contents of only 17 to 60 ppm, close to primitive arc magmas. Their parental magma, initially not Cu enriched, evolved to ≥60 ppm Cu in resultant gabbronorite emplaced at ca. 8 km. This was followed by strong Cu depletion (〈10 ppm) in the quartz-diorite porphyries associated with Cu mineralization. Most of the gabbronorites contain magmatic sulfide phases that have been partially dissolved by hydrothermal fluids. One sample contains sulfide droplets and coexisting silicate glass and fluid inclusions that were locally trapped in interstitial magmatic quartz. We conclude that the exsolution of a Cu-rich sulfide melt and its subsequent redissolution into aqueous fluids was a significant factor in the formation of the Mujicun porphyry Cu deposit, and that anomalous Cu enrichments in the mantle source regime or intracrustal cumulates were not required to form the ore deposit.
    Print ISSN: 0361-0128
    Topics: Geosciences
    Published by Society of Economic Geologists (SEG)
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  • 3
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    Extra strengthening and work hardening in gradient nanotwinned metals (2018)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publication Date: 2018
    Description: 〈p〉Gradient structures exist ubiquitously in nature and are increasingly being introduced in engineering. However, understanding structural gradient–related mechanical behaviors in all gradient structures, including those in engineering materials, has been challenging. We explored the mechanical performance of a gradient nanotwinned structure with highly tunable structural gradients in pure copper. A large structural gradient allows for superior work hardening and strength that can exceed those of the strongest component of the gradient structure. We found through systematic experiments and atomistic simulations that this unusual behavior is afforded by a unique patterning of ultrahigh densities of dislocations in the grain interiors. These observations not only shed light on gradient structures, but may also indicate a promising route for improving the mechanical properties of materials through gradient design.〈/p〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    Discovering the forbidden Raman modes at the edges of layered materials (2018)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2018
    Description: 〈p〉The edges of layered materials have unique properties that substantially differ from the body regions. In this work, we perform a systematic Raman study of the edges of various layered materials (MoS〈sub〉2〈/sub〉, WS〈sub〉2〈/sub〉, WSe〈sub〉2〈/sub〉, PtS〈sub〉2〈/sub〉, and black phosphorus). The Raman spectra of the edges feature newly observed forbidden Raman modes, which are originally undetectable from the body region. By selecting the edge type and the polarization directions of the incident and scattered light, all forbidden Raman modes are distinctly detected. Optical simulations show that the edges of layered materials drastically distort the electromagnetic fields of both the incident and scattered light, so that the light interacts with the edges in a distinct way, which differs from its interactions with the body regions.〈/p〉
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
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    DrugE-Rank: improving drug-target interaction prediction of new candidate drugs or targets by ensemble learning to rank (2016)
    Oxford University Press
    Details
    Publication Date: 2016-06-16
    Description: Motivation: Identifying drug–target interactions is an important task in drug discovery. To reduce heavy time and financial cost in experimental way, many computational approaches have been proposed. Although these approaches have used many different principles, their performance is far from satisfactory, especially in predicting drug–target interactions of new candidate drugs or targets. Methods: Approaches based on machine learning for this problem can be divided into two types: feature-based and similarity-based methods. Learning to rank is the most powerful technique in the feature-based methods. Similarity-based methods are well accepted, due to their idea of connecting the chemical and genomic spaces, represented by drug and target similarities, respectively. We propose a new method, DrugE-Rank, to improve the prediction performance by nicely combining the advantages of the two different types of methods. That is, DrugE-Rank uses LTR, for which multiple well-known similarity-based methods can be used as components of ensemble learning. Results: The performance of DrugE-Rank is thoroughly examined by three main experiments using data from DrugBank: (i) cross-validation on FDA (US Food and Drug Administration) approved drugs before March 2014; (ii) independent test on FDA approved drugs after March 2014; and (iii) independent test on FDA experimental drugs. Experimental results show that DrugE-Rank outperforms competing methods significantly, especially achieving more than 30% improvement in Area under Prediction Recall curve for FDA approved new drugs and FDA experimental drugs. Availability: http://datamining-iip.fudan.edu.cn/service/DrugE-Rank Contact: zhusf@fudan.edu.cn Supplementary information: Supplementary data are available at Bioinformatics online.
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
    Published by Oxford University Press
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  • 6
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    Quantum confinement of excitons in wurtzite InP nanowires (2015)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2015-05-20
    Description: Exciton resonances are observed in photocurrent spectra of 80 nm wurtzite InP nanowire devices at low temperatures, which correspond to transitions between the A, B, and C valence bands and the lower conduction band. Photocurrent spectra for 30 nm WZ nanowires exhibit shifts of the exciton resonances to higher energy, which are consistent with finite element calculations of wavefunctions of the confined electrons and holes for the various bands.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 7
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    Chemopreventive mechanism of polypeptides from Chlamy Farreri (PCF) against UVB-induced malignant transformation of HaCaT cells (2015)
    Oxford University Press
    Details
    Publication Date: 2015-02-17
    Description: To investigate polypeptide from Chlamy Farreri (PCF)’s protective effect against skin cancer, we used a cellular model of ultraviolet B (UVB)-induced malignant transformation. The human keratinocyte cell line HaCaT was repeatly exposed to UVB (10 mJ/cm 2 , 20 times) and malignant transformation was confirmed by Gimesa staining, cell cycle analysis and various assays [anchorage independent growth, matrix metalloproteinase-9 (MMP9) activity, plating efficiency]. The malignant transformation was found to be effectively prevented by PCF pretreatment (2.84mM for 2h prior to each UVB exposure). We investigated the mechanism of PCF-mediated action by determining its effect on DNA methylation status of the tumour suppressor genes [P16 and ras association domain family 1 A (RASSF1A)] in the UVB-transformed cells. Both genes were found to be hypermethylated by chronic UVB exposure. The expression levels of P16, RASSF1A, DNA methyltransferases (DNMTs) and DNA damage inducible protein a (GADD45a) were measured by reverse transcriptase-polymerase chain reaction and western blotting. While chronic UVB exposure was found to suppress the expression of P16 and RASSF1A, it enhanced the expression of DNMT3b. In the early phase of UVB-induced malignant transformation, the GADD45a expression was increased, however, it declined with a continued irradiation of the cells. The UVB-induced DNA hypermethylation of P16 and RASSF1A and subsequent gene silencing was reversed by PCF treatment. The inhibition of DNMTs expression suggested that PCF blocked DNA methylation and thereby the silencing of tumour suppressor genes. Furthermore, the PCF-mediated substantial increase in GADD45a expression indicated that PCF promoted demethylation of tumour suppressor genes via GADD45a induction.
    Print ISSN: 0267-8357
    Electronic ISSN: 1464-3804
    Topics: Biology , Medicine
    Published by Oxford University Press
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  • 8
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    Lower Thermospheric Enhanced Sodium Layers Observed at Low Latitude and Possible Formation: Case Studies (2013)
    Wiley
    Details
    Publication Date: 2013-02-28
    Description: [1]  We report two lower thermospheric enhanced sodium layer (TeSL) cases observed at a low latitude station, Lijiang, China (26.7°N, 100.0°E), on March 10 and April 10, 2012, respectively. The TeSLs in the two cases were located at altitudes near 122 and 112 km, respectively. In addition, strong sporadic sodium layers (SSLs) near 100 km accompanied the TeSL observed on March 10, 2012. Both the TeSLs and SSLs exhibited tidal-induced downward motion. The adjacent ground-based and space-borne ionospheric radio observations showed strong Es layers before the appearance of the TeSLs, suggesting an " Es – TeSLs (SSLs)" chain formed through the tidal wind shear mechanism. Assuming that the vertical tidal wavelengths remain unchanged, it is found that in different regions caused by the tidal wind shear, different TeSLs evolution processes are expected: (1) in a tidal-convergence region, a TeSL/SSL with a downward propagation phase is enhanced due to a rapid decrease in the Na + lifetime at the lower altitude; (2) in an ion convergence-divergence interface region, a TeSL/SSL will still follow the tidal downward phase progression, but sodium density does not exhibit evident enhancement; and (3) when a TeSL/SSL enters into a tidal wind-divergence zone, the layer density tends to decrease.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 9
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    Amorphous Co(OH)2 nanosheet electrocatalyst and the physical mechanism for its high activity and long-term cycle stability (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-01-20
    Description: Good conductivity is conventionally considered as a typical reference standard in terms of selecting water electrolysis catalysts. Cobalt hydroxide (Co(OH) 2 ) has received extensive attention for its exceptional properties as a promising electrocatalysis catalyst. However, research on Co(OH) 2 so far prefers to its crystal phase instead of amorphous phase because the former generally exhibits better conductivity. Here, we have demonstrated that the amorphous Co(OH) 2 electrocatalyst synthesized via a simple, facile, green, and low-cost electrochemistry technique possesses high activity and long-term cycle stability in the oxygen evolution reaction (OER). The as-synthesized Co(OH) 2 electrode was found to be a promising electrocatalyst for mediating OER in alkaline media, as evidenced by the overpotential of 0.38 V at a current density of 10 mA cm −2 and a Tafel slope of 68 mV dec −1 . The amorphous Co(OH) 2 also presented outstanding durability and its stability was just as well as that of crystalline Co(OH) 2 . Generally, the integrated electrochemical performances of the amorphous Co(OH) 2 in the OER process were much superior to that of the crystalline Co(OH) 2 materials. We also established that the short-range order, i.e., nanophase, of amorphous Co(OH) 2 creates a lot of active sites for OER which can greatly promote the electrocatalysis performance of amorphous catalysts. These findings showed that the conventional understanding of selecting electrocatalysts with conductivity as a typical reference standard seems out of date for developing new catalysts at the nanometer, which actually open a door to applications of amorphous nanomaterials as an advanced electrocatalyst in the field of water oxidation.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 10
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    SerRS-tRNASec complex structures reveal mechanism of the first step in selenocysteine biosynthesis (2015)
    Oxford University Press
    Details
    Publication Date: 2015-12-02
    Description: Selenocysteine (Sec) is found in the catalytic centers of many selenoproteins and plays important roles in living organisms. Malfunctions of selenoproteins lead to various human disorders including cancer. Known as the 21st amino acid, the biosynthesis of Sec involves unusual pathways consisting of several stages. While the later stages of the pathways are well elucidated, the molecular basis of the first stage—the serylation of Sec-specific tRNA (tRNA Sec ) catalyzed by seryl-tRNA synthetase (SerRS)—is unclear. Here we present two cocrystal structures of human SerRS bound with tRNA Sec in different stoichiometry and confirm the formation of both complexes in solution by various characterization techniques. We discovered that the enzyme mainly recognizes the backbone of the long variable arm of tRNA Sec with few base-specific contacts. The N-terminal coiled-coil region works like a long-range lever to precisely direct tRNA 3' end to the other protein subunit for aminoacylation in a conformation-dependent manner. Restraints of the flexibility of the coiled-coil greatly reduce serylation efficiencies. Lastly, modeling studies suggest that the local differences present in the D- and T-regions as well as the characteristic U20:G19:C56 base triple in tRNA Sec may allow SerRS to distinguish tRNA Sec from closely related tRNA Ser substrate.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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