Seismological research in Yunnan Province, China, and its tectonic implication between the Xianshuihe-Xiaojiang fault system and the Red River fault zone

The tectonic crosscutting relationship between the two most tectonic important Xianshuihe-Xiaojiang fault system (XFS) and the Red River fault zone (RRF) is a key basic problem but it is controversial now. These obscure further leads to a hot argument about the geodynamic model of the southeast margin of the Tibetan Plateau. In order to answer whether the XFS has cut across the RRF and extended southwardly, multiple seismological methods, including seismic relocation, b-value analysis, seismic energy, density study, focal mechanism inversion, and regional stress field research, are applied in the Yunnan Province area, China, where the XFS and the RRF intersects with each other. The results comprehensively demonstrate that the southern segment of the XFS has not been affected by the RRF, and it has continued for a length after crossing the RRF, but the Dian Bien Phu fault zone should not be an extension fault of the XFS. Along the SW direction, starting from the middle segment of the XFS, and cutting across the Qujiang fault, Shiping-Jianshui fault zone, RRF, Ailaoshan fault zone, Wuliangshan fault zone, and the southern section of the Daluo fault, the belt should be treated as the eastern boundary of the clockwise rotational in geodynamics model of the Tibetan Plateau in this study area. Based on these conclusion above and previous recognitions, a new geodynamic evolution model is proposed

Ultraquantum magnetoresistance in Kramers Weyl semimetal candidate β\beta-Ag2Se

The topological semimetal $\beta$-Ag2Se features a Kramers Weyl node at the origin in momentum space and a quadruplet of spinless Weyl nodes, which are annihilated by spin-orbit coupling. We show that single crystalline $\beta$-Ag2Se manifests giant Shubnikov-de Haas oscillations in the longitudinal magnetoresistance which stem from a small electron pocket that can be driven beyond the quantum limit by a field less than 9 T. This small electron pocket is a remainder of the spin-orbit annihilatedWeyl nodes and thus encloses a Berry-phase structure. Moreover, we observed a negative longitudinal magnetoresistance when the magnetic field is beyond the quantum limit. Our experimental findings are complemented by thorough theoretical band structure analyses of this Kramers Weyl semimetal candidate, including first-principle calculations and an effective k*p model.Comment: A new version based on arXiv:1502.0232

Reaction Chemistry and Kinetics of Corn Stalk Pyrolysis without and with Ga/HZSM-5

The bifunctional Ga/HZSM-5 catalyst has been proven having the capability to increase the selectivity of aromatics production during catalytic pyrolysis of furan and woody biomass. However, the reaction chemistry and kinetics of pyrolysis of herbaceous biomass promoted by Ga/HZSM-5 is rarely reported. Pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) analysis and non-isothermal thermogravimetric analysis at four heating rates were carried out to investigate the decomposition behavior and pyrolysis kinetics of corn stalk without and with Ga/HZSM-5. The effective activation energies for corn stalk pyrolysis were calculated by using the Friedman isoconversional method. The Py–GC/MS analysis results indicated that the Ga/HZSM-5 catalyst had a high selectivity toward producing the aromatic chemicals of xylene, toluene and benzene, whereas the major products from non-catalytic pyrolysis of corn stalk were oxygenated compounds. The presence of Ga/HZSM-5 could significantly reduce the effective activation energies of corn stalk pyrolysis from 159.9–352.4 kJ mol−1 to 41.6–99.8 kJ mol−1 in the conversion range of 0.10–0.85

Characterization and Distribution of the autB Gene in Neisseria meningitidis

We aimed to investigate and understand the characterization and distribution of the autB gene in Neisseria meningitidis in China. autB is flanked by two conservative genes, smpB and glcD, and it can be present in the majority of meningococcal isolates, but not in 053442 of clonal complex 4821 (CC4821) which contains a 968 bp sequence. In this study, we sequenced the intervenient region between smpB and glcD in 178 Chinese N. meningitidis strains isolated from both patients and carriers. There were 110 serogroupable strains, other 68 were non-groupable (NG). Ninety nine of the 178 strains were clustered into 13 CCs, the remaining 79 were unassigned (UA). CC4821 is one of the dominant CCs in China. Forty of the 42 CC4821 strains and 26 of the 79 UA strains were autB-null, while the remaining 12 CCs were autB-positive. According to the N-terminal sequence, most (97/112) of the autB-positive strains were clustered into AutB1 and the remaining 15 were AutB2. The autB gene and its flanking intergenic sequences was superseded by a perfectly conservative sequence of an identical 968 bp in all of the autB-null N. meningitidis strains which had no identity with the relatively conservative intergenic sequences that flanked the autB gene in autB-positive strains. There was a 10 bp DNA uptake sequence (DUS) at the beginning of the interval 968 bp sequence in the autB-null strains while there was a 9 bp Haemophilus-specific uptake sequence (hUS) at the beginning of the partial holB gene and at the end of the partial tmk gene in autB-positive strains, holB and tmk gene were flanking the autB gene in Haemophilus. In conclusion, not all pathogenic N. meningitidis strains especially CC4821 possess the autB gene in China and the corresponding spacer region of the autB-null strains was not homologous to that found in autB-positive strains. There's a hypothesis that the DUS and hUS are likely to play a key part in the mechanism of uptake or loss of the autB gene

UUDAT based on the modular multilevel converter and diode bridges for high-voltage DC application

Conventional unidirectional DC/DC converters for high-voltage direct current application employ DC/AC/DC technology and suffer from high converter cost and power loss. To solve these issues, a unidirectional step-up DC–DC autotransformer (UUDAT) is studied. UUDAT is composed of the series connection of diode bridges and voltage source converters. Topologies of UUDAT is detailed. The harmonic and uncontrollability issues are discussed. Control and the possible application scenario for UUDAT are proposed. The ways of dimensioning the voltage and power rating of the components in UUDAT are studied. Extensive simulations on the power system level verified the technical feasibility of UUDATs

Stress changes on major faults caused by 2013 Lushan earthquake and its relationship with 2008 Wenchuan earthquake

On April 20, 2013, an M s7.0 earthquake occurred in Ya'an-Lushan region, Sichuan Province, China, killing and injuring more than one thousand people. Therefore, it is critical to outline the areas with potential aftershocks before reconstruction and re-settlement as to avoid future disasters. Based on the elastic dislocation theory and multi-layered lithospheric model, we calculate the co- and post-seismic stress changes caused by the Wenchuan and Lushan earthquakes to discuss the relationship between M w7.9 Wenchuan earthquake and M s7.0 Lushan earthquake, the influences on the distribution of aftershock caused by the Lushan earthquake, and the stress changes on major faults in this region. It is shown that the Coulomb failure stress increment on the hypocenter of Lushan earthquake caused by the Wenchuan earthquake is about 0.0037-0.0113 MPa. And the possible maximum value (0.0113 MPa) is larger than the threshold of stress triggering. Therefore, the occurrence of Lushan earthquake is probably effectively promoted by the Wenchuan earthquake. The aftershock distribution is well explained by the co-seismic stress changes of Lushan earthquake. By the two ends of the rupture of Lushan earthquake with increased Coulomb failure stress, a lack of aftershock recordings indicates the high seismic hazard. The stress accumulation and corresponding seismic hazard on the Kangding-Dafu segment of the Xinshuihe fault, the Beichuan-Yingxiu fault, the Pengxian-Guanxian fault, and the Ya'an fault are further increased by the Lushan earthquake and post-seismic process of Wenchuan earthquake.8 page(s

A New Hybrid Reciprocating Compressor Model Coupled with Acoustic FEM Characterization and Gas Dynamics

Accurate comprehension of thermodynamic demeanor and pressure pulsation propagation is of great attractiveness in a reciprocating compressor system. To consider the reciprocal interaction between compressor and pipelines, a hybrid numerical model is thus built by coupling the in-cylinder lumped parameter approach, in-pipe 1D gas dynamics and 3D acoustic characteristics of chambers. The transmission and reflection coefficients of a geometrically complex chamber are achieved by the definition of an acoustic characterization method based on acoustic FEM simulation data, with a high level of accuracy. Numerical results of this new hybrid model are compared with predictions from the traditional hybrid model with in-pipe 1D gas dynamics, together with experimental data. Through comparison analysis, the advantages are highlighted in using the acoustic FEM characterization for complex elements since the new model performs numerical solution without introducing any simplifications to the geometry of fluid domain

Facile synthesis of single-nickel-atomic dispersed N-doped carbon framework for efficient electrochemical CO2 reduction

While converting carbon dioxide (CO2) into value-added carbon products by electrolyzing offers a promising approach to mitigate global warming and store energy, poor selectivity and stability of catalysts still impede this conversion. Single-atom catalyst exhibits exceptional selectivity for CO2 electroreduction reaction in response to inhibiting hydrogen evolution reaction (HER), which is the major obstacle to the development of CO2 reduction. Herein we introduce a facile approach to obtain Ni-Nx sites encapsulating into carbon nanotubes with a nickel loading as high as 6.63 wt%. This catalyst exhibits high Faradaic efficiency approximately 95% for CO2 electroreduction to carbon monoxide (CO) in the wide potential range from - 0.7 to -1.0 V, and the current density reaches 57.1 mA cm(-2) at -1.0 V versus a reversible hydrogen electrode (RHE). Experiments and characterization results demonstrate that nickel chemical state and content play a vital role for CO2 electrocatalytic performance. Moreover, the simplifying of the synthesis may shed a new light on design single atom catalysts of electrochemistry in addition to CO2 reduction