Chengdu University of Technology

The Daya Bay Reactor Neutrino Experiment has measured a nonzero value for the neutrino mixing angle ${\ensuremath{\theta}}_{13}$ with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 $\mathrm{G}{\mathrm{W}}_{\mathrm{th}}$ reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With a $43\text{ }000\text{ }\text{ }\mathrm{ton}--\mathrm{G}{\mathrm{W}}_{\mathrm{th}}--\mathrm{day}$ live-time exposure in 55 days, 10 416 (80 376) electron-antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is $R=0.940\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0ex}{0ex}}0.011(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.004(\mathrm{syst}.)$. A rate-only analysis finds ${sin}^{2}2{\ensuremath{\theta}}_{13}=0.092\ifmmode\pm\else\textpm\fi{}0.016(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.005(\mathrm{syst}.)$ in a three-neutrino framework.

Abstract Large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking. Most moderate‐ and large‐magnitude earthquakes trigger landslides, ranging from small failures in the soil cover to massive, devastating rock avalanches. Some landslides dam rivers and impound lakes, which can collapse days to centuries later, and flood mountain valleys for hundreds of kilometers downstream. Landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows. Cracks and fractures can form and widen on mountain crests and flanks, promoting increased frequency of landslides that lasts for decades. More gradual impacts involve the flushing of excess debris downstream by rivers, which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency, settlements, ecosystems, and infrastructure. Ultimately, earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales. Two recent events have attracted intense research into earthquake‐induced landslides and their consequences: the magnitude M 7.6 Chi‐Chi, Taiwan earthquake of 1999, and the M 7.9 Wenchuan, China earthquake of 2008. Using data and insights from these and several other earthquakes, we analyze how such events initiate processes that change mountain landscapes, highlight research gaps, and suggest pathways toward a more complete understanding of the seismic effects on the Earth's surface.

The surface uplift history of the Tibetan Plateau and Himalaya is among the most interesting topics in geosciences because of its effect on regional and global climate during Cenozoic time, its influence on monsoon intensity, and its reflection of the dynamics of continental plateaus. Models of plateau growth vary in time, from pre-India-Asia collision (e.g., approximately 100 Ma ago) to gradual uplift after the India-Asia collision (e.g., approximately 55 Ma ago) and to more recent abrupt uplift (<7 Ma ago), and vary in space, from northward stepwise growth of topography to simultaneous surface uplift across the plateau. Here, we improve that understanding by presenting geologic and geophysical data from north-central Tibet, including magnetostratigraphy, sedimentology, paleocurrent measurements, and (40)Ar/(39)Ar and fission-track studies, to show that the central plateau was elevated by 40 Ma ago. Regions south and north of the central plateau gained elevation significantly later. During Eocene time, the northern boundary of the protoplateau was in the region of the Tanggula Shan. Elevation gain started in pre-Eocene time in the Lhasa and Qiangtang terranes and expanded throughout the Neogene toward its present southern and northern margins in the Himalaya and Qilian Shan.

Thanks to the line-of-sight (LoS) transmission and flexibility, unmanned aerial vehicles (UAVs) effectively improve the throughput of wireless networks. Nevertheless, the LoS links are prone to severe deterioration by complex propagation environments, especially in urban areas. Reconfigurable intelligent surfaces (RISs), as a promising technique, can significantly improve the propagation environment and enhance communication quality by intelligently reflecting the received signals. Motivated by this, the joint UAV trajectory and RIS's passive beamforming design for a novel RIS-assisted UAV communication system is investigated to maximize the average achievable rate in this letter. To tackle the formulated non-convex problem, we divide it into two subproblems, namely, passive beamforming and trajectory optimization. We first derive a closed-form phase-shift solution for any given UAV trajectory to achieve the phase alignment of the received signals from different transmission paths. Then, with the optimal phase-shift solution, we obtain a suboptimal trajectory solution by using the successive convex approximation (SCA) method. Numerical results demonstrate that the proposed algorithm can considerably improve the average achievable rate of the system.

The present work theoretically and experimentally provides an insight into the internal mechanism of Li⁺ transport within an artificial hybrid SEI layer consisting of lithium-antimony (Li₃Sb) alloy and lithium fluoride (LiF).

The surface uplift history of the Tibetan Plateau (TP) offers a key testing ground for evaluating models of collisional tectonics and holds important implications for processes ranging from global cooling to the onset of the Asian monsoon. Various models have been proposed to reveal the surface uplift history of the TP, but controversies remain. We evaluate these models using data from sedimentology and stratigraphy, structural geology, magmatism, exhumation, and paleoaltimetry studies. Structural analyses indicate that thrust belts, which spread from the central TP outward toward its surrounding margins, accommodated most of the India–Asia convergence, and facilitated crustal shortening and thickening in the central TP. Eocene adakitic rocks located in the Qiangtang and the Lhasa blocks likely were generated by partial melting of an eclogitic source. Paleogene (50–30 Ma) potassic rocks only occur in the Qiangtang block, whereas Late Oligocene–Late Miocene (26–8 Ma) potassic rocks occur both in the Qiangtang and Lhasa blocks. Low-temperature thermochronologic ages in the central TP are older than 40–35 Ma, whereas those in the margins are younger than 20 Ma (mostly Late Miocene, and Pliocene/Pleistocene in age). Independent paleoaltimetry estimates suggest that the Lhasa and Qiangtang terranes attained their current elevations during the Eocene, most likely due to the initial collision between India and Lhasa, whereas the Hoh Xil basin area to the north and Himalayas to the south were still low, even below sea level in the latter case. We argue for an inside-out growth pattern for the Tibetan Plateau. The TP grew southward and northward from a nucleus of high topography and is likely to continue expanding along the Mazar Tagh fault to the northwest, the Kuantai Shan-Hei Shan-Longshou Shan to the northeast, the Longquan Shan to the east and the Shillong plateau to the south if the northward force of India would not diminished.

Human life comes to a standstill as many countries shut themselves off from the work due to the novel coronavirus disease pandemic (COVID-19) that hit the world severely in the first quarter of 2020. All types of industries, vehicle movement, and people's activity suddenly halted, perhaps for the first time in modern history. For a long time, it has been stated in various literature that the increased industrialization and anthropogenic activities in the last two decades polluted the atmosphere, hydrosphere, and biosphere. Since the industries and people's activities have been shut off for a month or more in many parts of the world, it is expected to show some improvement in the prevailing conditions in the aforementioned spheres of environment. Here, with the help of remote sensing images, this work quantitatively demonstrated the improvement in surface water quality in terms of suspended particulate matter (SPM) in the Vembanad Lake, the longest freshwater lake in India. The SPM estimated based on established turbidity algorithm from Landsat-8 OLI images showed that the SPM concentration during the lockdown period decreased by 15.9% on average (range: -10.3% to 36.4%, up to 8 mg/l decrease) compared with the pre-lockdown period. Time series analysis of satellite image collections (April 2013 - April 2020) showed that the SPM quantified for April 2020 is the lowest for 11 out of 20 zones of the Vembanad lake. When compared with preceding years, the percentage decrease in SPM for April 2020 is up to 34% from the previous minima.

The steep, high‐relief eastern margin of the Tibetan Plateau has undergone rapid Cenozoic cooling and denudation yet shows little evidence for large‐magnitude shortening or accommodation generation in the foreland basin. We address this paradox by using a variety of geomorphic observations to place constraints on the kinematics and slip rates of several large faults that parallel the plateau margin. The Beichuan and Pengguan faults are active, dominantly dextral‐slip structures that can be traced continuously for up to 200 km along the plateau margin. Both faults offset fluvial fill terraces that yield inheritance‐corrected, cosmogenic 10 Be exposure ages of &lt;15 kyr, indicating latest Pleistocene activity. The Pengguan fault appears to have been active in the Holocene at two sites along strike. Latest Quaternary apparent throw rates on both faults are variable along strike but are typically &lt;1 mm yr −1 . Rates of strike‐slip displacement are likely to be several times higher, probably ∼1–10 mm yr −1 but remain poorly constrained. Late Quaternary folding and dextral strike‐slip has also occurred along the western margin of the Sichuan Basin, particularly associated with the present‐day mountain front. These observations support models for the formation and maintenance of the eastern plateau margin that do not involve major upper crustal shortening. They also suggest that activity on the margin‐parallel faults in eastern Tibet may represent a significant seismic hazard to the densely populated Sichuan Basin.

The Panzhihua gabbroic layered intrusion is associated with the 260 Ma Emeishan Large Igneous Province in SW China. This sill-like body hosts a giant Fe-Ti-V oxide deposit with 1333 million ton ore reserves, which makes China a major producer of these metals. The intrusion has a Marginal zone of fine-grained hornblende-bearing gabbro and olivine gabbro, followed upward by Lower, Middle, and Upper zones. The Lower and Middle zones consist of layered melanogabbro and gabbro composed of cumulate clinopyroxene, plagioclase, and olivine. These zones also contain magnetite layers. The Upper zone consists chiefly of leucogabbro composed of plagioclase and clinopyroxene with minor olivine. Most rocks in the body show variable-scale rhythmic modal layering in which dark minerals, primarily clinopyroxene, dominate in the lower parts of each layer, and lighter minerals, primarily plagioclase, dominate in the upper parts. The oxide ores occur as layers and lenses within the gabbros and are concentrated in the lower parts of the intrusion. Ore textures and associated mineral assemblages indicate that the ore bodies formed by very late-stage crystallization of V-rich titanomagnetite from an immiscible oxide liquid in a fluid-rich environment. The rocks of the Panzhihua intrusion become more evolved in chemistry upward and follow a tholeiitic differentiation trend with enrichment in Fe, Ti, and V. They are enriched in light rare earth elements relative to heavy rare earth elements, and exhibit positive Nb, Ta, and Ti anomalies and negative Zr and Hf anomalies. The silicate rocks and oxide ores of the Panzhihua intrusion formed from highly evolved Fe-Ti-V-rich ferrobasaltic or ferropicritic magmas. The textures of the ores and the abundance of minor hydrous phases indicate that addition of fluids from upper crustal wall-rocks induced the separation of the immiscible oxide melts from which the Fe-Ti-V oxide ore bodies in the lower part of the intrusion crystallized. © The Author 2005. Published by Oxford University Press. All rights reserved.

A series of ordered mesoporous Ni–Ce–Al composite oxides with various cerium contents were synthesized via a one-pot route: evaporation-induced self-assembly (EISA) strategy and tested in methane dry reforming for hydrogen and synthesis gas production. Using this method, the hydrophobic nickel precursor was directly incorporated into the hydrophobic cores of surfactant micelles, and thus, the highly dispersed Ni nanoparticles were stabilized inside the mesopore channels of an alumina matrix. For comparison, Ni-based catalysts were also prepared by a traditional impregnation method. The characterization results confirmed that the ordered mesostructures were well maintained in all of the cerium-incorporated Ni–Al materials (Ce/(Ce + Al) molar ratio ≤ 3%). The catalyst with a Ce/(Ce + Al) ratio of 1% exhibited the highest catalytic activity (with CO2 and CH4 initial conversions being 70% and 68% at 700 °C, respectively) and remained stable in a methane dry reforming reaction. This improved activity can be attributed to the large surface area and high dispersion and reducibility of Ni nanoparticles, which were stable because of the stable alumina framework and high oxygen mobility in these cerium-containing samples. Resistance to carbon deposition was found over the Ni–Ce–Al catalyst, whereas amounts of graphitic carbon species were found over the Ni-impregnated catalysts, which was responsible for deactivation.

The geochemical composition of the Middle-Upper Proterozoic turbidites in Hunan, South China is related to provenance and tectonic setting of the sedimentary basin. The turbidites are characterized by moderate SiO 2 contents (Al 2 O 3 /SiO 2 typically 0.1-0.3) and moderate K 2 O/Na 2 O ratios (generally 0.1-0.3) but relatively high Fe 2 O 3 * + MgO contents (5-10 wt %) and unusually low contents of CaO (typically < 1 wt %). Abundances of ferromagnesian trace elements and incompatible elements are moderate. The REE patterns are uniform and similar to the upper continental crust and typical post-Archean shales, with LREE enrichment, flat HREE, and significant negative Eu-anomalies. In general, the slates show higher contents of Fe 2 O 3 * + MgO and ferromagnesian trace elements, and lower ratios of La/Sc and Th/Sc than the associated graywackes, suggesting that more mafic materials were incorporated into the clay-size fraction. Compared to the Upper Proterozoic Banxi Group, the Middle Proterozoic Lengjiaxi Group has higher concentrations for most ferromagnesian trace elements and lower La/Sc ratios, implying more mafic components in the provenance of the latter. The relationship among alkali and alkaline earth elements, the Chemical Index of Alteration (CIA), and the Th/U ratios indicate that the source area was affected by a moderate weathering history. The main source was old continental crust (the Yangtze craton) dominated by felsic rocks of magmatic origin, with a variable admixture of mafic components from continental island arcs (e.g., the Fangjingshan-Dayong and the Sibao-Yiyang island arc chains). The flysch deposition took place in a back arc basin, rather than a failed intracontinental rift as proposed by some workers. We suggest that suturing between the Yangtze and Cathaysia blocks did not occur until late Proterozoic time and that the final assembly of the supercontinent Rodinia in South China was probably marked by the Jingning orogeny at ∼0.8 Ga.

ABSTRACT The lacustrine shale of the Upper Cretaceous Qingshankou Formation is the principal prospective unconventional target lithology, acting as source, reservoir, and seal. Lithofacies and associated storage capacity are two significant factors in shale oil prospectivity. This paper describes an investigation of the lower Qingshankou Formation lacustrine shale based on detailed description and analysis of cores, shale lithofacies characteristics, depositional setting, and stacking patterns. Seven lithofacies are recognized based on organic matter content, sedimentary structure, and mineralogy, all exhibiting rapid vertical and lateral changes controlled by the depositional setting and basin evolution. An overall trend from shallow-water to deep-water depositional environments is interpreted from the characteristics of the infilling sequences, characterized by increasing total organic carbon (TOC) and total clay content and decreasing layer thickness (i.e., from bedded to laminated then to massive sedimentary structures). Periods of deposition during shallowing cycles show a reverse trend in the sedimentary characteristics described above. The sedimentary rocks in the studied interval show three complete short-term cycles, each one containing progressive and regressive system tracts. Massive siliceous mudstones with both high and moderate TOC are considered to have the best hydrocarbon generation potential. Laminated siliceous mudstones, bedded siltstones, and calcareous mudstones with moderate and low TOC could have the same high hydrocarbon saturations as the high-TOC massive siliceous mudstones, but these lithologies contain more brittle minerals than the massive mudstones. Several siltstone samples show low or zero saturation of in situ hydrocarbons; this is considered to be related to a combination of fair to poor hydrocarbon generation potential and extremely low permeability, limiting migration. Moderate-TOC laminated siliceous mudstones were also observed to have connective pore-fracture networks. It can be demonstrated that successive thick sequences of moderate-TOC laminated siliceous mudstones, showing high volumes of hydrocarbon in situ, a high mineral brittleness index, and good permeability, combine to form shale oil exploration “sweet spots.”

Abstract The aprotic lithium–oxygen (Li–O 2 ) battery has excited huge interest due to it having the highest theoretical energy density among the different types of rechargeable battery. The facile achievement of a practical Li–O 2 battery has been proven unrealistic, however. The most significant barrier to progress is the limited understanding of the reaction processes occurring in the battery, especially during the charging process on the positive electrode. Thus, understanding the charging mechanism is of crucial importance to enhance the Li–O 2 battery performance and lifetime. Here, recent progress in understanding the electrochemistry and chemistry related to charging in Li–O 2 batteries is reviewed along with the strategies to address the issues that exist in the charging process at the present stage. The properties of Li 2 O 2 and the mechanisms of Li 2 O 2 oxidation to O 2 on charge are discussed comprehensively, as are the accompanied parasitic chemistries, which are considered as the underlying issues hindering the reversibility of Li–O 2 batteries. Based on the detailed discussion of the charging mechanism, innovative strategies for addressing the issues for the charging process are discussed in detail. This review has profound implications for both a better understanding of charging chemistry and the development of reliable rechargeable Li–O 2 batteries in the future.

The preparation of subnanoporous covalent-organic-framework (COF) membranes with high performance for ion/molecule sieving still remains a great challenge. In addition to the difficulties in fabricating large-area COF membranes, the main reason is that the pore size of 2D COFs is much larger than that of most gas molecules and/or ions. It is urgently required to further narrow their pore sizes to meet different separation demands. Herein, we report a simple and scalable way to grow large-area, pliable, free-standing COF membranes via a one-step route at organic-organic interface. The pore sizes of the membranes can be adjusted from >1 nm to sub-nm scale by changing the stacking mode of COF layers from AA to AB stacking. The obtained AB stacking COF membrane composed of highly-ordered nanoflakes is demonstrated to have narrow aperture (∼0.6 nm), uniform pore distribution and shows good potential in organic solvent nanofiltration, water treatment and gas separation.

We report an improved measurement of the neutrino mixing angle θ13 from the Daya Bay Reactor Neutrino Experiment. We exclude a zero value for sin22θ13 with a significance of 7.7 standard deviations. Electron antineutrinos from six reactors of 2.9 GWthwere detected in six antineutrino detectors deployed in two near (flux-weighted baselines of 470 m and 576 m) and one far (1648 m) underground experimental halls. Using 139 days of data, 28909 (205308) electron antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to the expected number of antineutrinos assuming no oscillations at the far hall is 0.944±0.007(stat.)±0.003(syst.). An analysis of the relative rates in six detectors finds sin22θ13=0. 089±0.010(stat.)±0.005(syst.) in a three-neutrino framework. © 2013 Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Sciences and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.

The eastern margin of the Tibetan Plateau combines very high relief with almost no Tertiary foreland sedimentation and little evidence of Cenozoic tectonic shortening. While river incision and landscape development at the plateau margin have received significant attention over the last decade, little is known about the Cenozoic development of the adjacent Sichuan Basin. Here we assess the Cenozoic thermal history of this basin using detrital apatite fission track (AFT) and (U‐Th)/He techniques and establish the presence of an exhumed AFT paleopartial annealing zone across much of the basin. This observation, combined with stratigraphic and borehole sections and inverse modeling of confined apatite fission tracks, indicates that the strata within the basin have undergone accelerated cooling after ∼40 Ma, consistent with the widespread erosion of ∼1 to 4 km of overlying sedimentary material. This regional‐scale erosion is most likely a response to changes in the Yangtze River system draining and removing sediment from the basin. The base‐level fall associated with this erosion contributed to a relative increase in relief across the Longmen Shan and may have helped drive Miocene‐Recent incision and unloading of the plateau margin.

Abstract Constructing three‐dimensional (3D) structural characteristics on two‐dimensional (2D) covalent organic frameworks (COFs) is a good approach to effectively improve the permeability and mass transfer rate of the materials and realize the rapid adsorption for guest molecules, while avoiding the high cost and monomer scarcity in preparing 3D COFs. Herein, we report for the first time a series of colyliform crystalline 2D COFs with quasi‐three‐dimensional (Q‐3D) topologies, consisting of unique “stereoscopic” triangular pores, large interlayer spacings and flexible constitutional units which makes the pores elastic and self‐adaptable for the guest transmission. The as‐prepared QTD‐COFs have a faster adsorption rate (2.51 g h −1 ) for iodine than traditional 2D COFs, with an unprecedented maximum adsorption capacity of 6.29 g g −1 . The excellent adsorption performance, as well as the prominent irradiation stability allow the QTD‐COFs to be applied for the rapid removal of radioactive iodine.

A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9 GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3) eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(μμ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.

Abstract Developing efficient and durable electrocatalysts for the oxygen evolution reaction (OER) in acidic media is attractive but still challenging. In this study, ultrafine defective RuO 2 nanoparticles are successfully prepared on carbon cloth by means of dip‐coating, annealing, and acid etching. As a self‐supported electrocatalyst, it exhibits an ultralow overpotential of 179 mV in 0.5 m H 2 SO 4 . More importantly, the high activity can be well maintained for 20 h. The density functional calculations revealed that the defect can not only increase the number of active sites but also improve the intrinsic OER activity.

The quality of digital elevation models (DEMs), as well as their spatial resolution, are important issues in geomorphic studies. However, their influence on landslide susceptibility mapping (LSM) remains poorly constrained. This work determined the scale dependency of DEM-derived geomorphometric factors in LSM using a 5 m LiDAR DEM, LiDAR resampled 30 m DEM, and a 30 m ASTER DEM. To verify the validity of our approach, we first compiled an inventory map comprising of 267 landslides for Sihjhong watershed, Taiwan, from 2004 to 2014. Twelve landslide causative factors were then generated from the DEMs and ancillary data. Afterward, popular statistical and machine learning techniques, namely, logistic regression (LR), random forest (RF), and support vector machine (SVM) were implemented to produce the LSM. The accuracies of models were evaluated by overall accuracy, kappa index and the receiver operating characteristic curve indicators. The highest accuracy was attained from the resampled 30 m LiDAR DEM derivatives, indicating a fine-resolution topographic data does not necessarily achieve the best performance. Additionally, RF attained superior performance between the three presented models. Our findings could contribute to opt for an appropriate DEM resolution for mapping landslide hazard in vulnerable areas.