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Oxygen-affected cracking commonly presents on thin Ni-based single crystal superalloy components serving in high temperature and oxidizing environments. This study uses a newly developed in-situ thermal-stress environmental transmission electron microscope to investigate the oxidation and fracture behaviors of Ni-based single crystal superalloy at 650°C under stress. The in-situ oxidation was found to change the tensile fracture mode from the close-packed {111} planes of plastic fracture to $ \{001\} $ planes adjacent to γ/γ′ interfaces of brittle fracture. The microanalysis also revealed that the γ′ cuboids, γ phase, and γ/γ interface exhibit different oxidation behavior, thus underscoring the thickness debit effect.

Atmospheric aerosols have effects on atmospheric radiation assessments, global climate change, local air quality and visibility. In particular, aerosols are more likely transformed and accumulated in winter. In this paper, we used the Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument to study the characteristics of aerosol type and contributions of PM2.5 chemical components to aerosol extinction (AE), vertical distribution of aerosols, and source. From December 30, 2018 to January 27, 2019, we conducted MAX-DOAS observations on Sanmenxia. The proportion of PM2.5 to PM10 was 69.48%–95.39%, indicating that the aerosol particles were mainly fine particles. By analyzing the ion data and modifying Interagency Monitoring of Protected Visual Environments (IMPROVE) method, we found that nitrate was the largest contributor to AE, accounting for 31.51%, 28.98%, and 27.95% of AE on heavily polluted, polluted, and clean days, respectively. NH4+, OC, and SO42− were also major contributors to AE. The near-surface aerosol extinction retrieved from MAX-DOAS measurement the PM2.5 and PM10 concentrations measured by an Unmanned Aerial Vehicle (UAV) have the same trend in vertical distribution. AE increased about 3 times from surface to 500 m. With the backward trajectory of the air mass during the haze, we also found that the continuous heavy pollution was mainly caused by transport of polluted air from the northeast, then followed by local industrial emissions and other sources of emissions under continuous and steady weather conditions.

The effects of rare earth elements (Ce, Eu, and Er) doping on the microstructure and gas sensing properties of ZnO nanowires were investigated. The Ce, Eu, Er-doped ZnO nanowires and pristine ZnO nanowires were synthesized via a solvothermal route. The structure of the prepared samples was studied and compared by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron microscopy. The gas sensors were fabricated by coating the prepared samples on aluminum oxides tube-based Au sensing electrode, with Ni-Cr heating wire to control the operating temperature. The operating temperature of all sensors was determined to be 300 °C with consideration of ethanol response. At this temperature, all sensors showed good ethanol sensing performance, with the 1%Ce-doped ZnO nanowires-based sensor exhibited the highest ethanol response over the other sensors. The mechanism for the microstructure and gas sensing behavior difference of various samples was discussed.

Microseismic (MS) event locations are vital aspect of MS monitoring technology used to delineate the damage zone inside the surrounding rock mass. However, complex geological conditions can impose significantly adverse effects on the final location results. To achieve a high-accuracy location in a complex cavern-containing structure, this study develops an MS location method using the fast marching method (FMM) with a second-order difference approach (FMM2). Based on the established velocity model with three-dimensional (3D) discrete grids, the realization of the MS location can be achieved by searching the minimum residual between the theoretical and actual first arrival times. Moreover, based on the calculation results of FMM2, the propagation paths from the MS sources to MS sensors can be obtained using the linear interpolation approach and the Runge–Kutta method. These methods were validated through a series of numerical experiments. In addition, our proposed method was applied to locate the recorded blasting and MS events that occurred during the excavation period of the underground caverns at the Houziyan hydropower station. The location results of the blasting activities show that our method can effectively reduce the location error compared with the results based on the uniform velocity model. Furthermore, the obtained MS location was verified through the occurrence of shotcrete fractures and spalling, and the monitoring results of the in-situ multipoint extensometer. Our proposed method can offer a more accurate rock fracture location and facilitate the delineation of damage zones inside the surrounding rock mass.

Understanding the inconsistent rock fracture toughness (KIc) measurement results from different test specimen geometries helps provide suitable fracture parameters for engineering applications, predict rock fracture load, and assess the safety of flawed rock engineering structures. In this study, fracture experiments using full- or half-disc specimens with chevron notches or straight-through notches were conducted. Experimental results show that the notch types and loading methods (Brazilian-type diametric compression and three-point bending) significantly affect the KIc measurements. It is indicated that only considering the T-stress or fracture process zone (FPZ) alone cannot explain the test results well, while a good agreement is found between the experimental results and the interpretation based on the combined effects of T-stress and FPZ. Moreover, Brazilian-type compression and three-point bending under a short support span can make the full- or half-disc specimens have higher negative T-stress and larger FPZ, thus producing lower KIc values than three-point bending under a relatively long support span. Compared with KIc measurements using the straight-through notch specimens, those utilizing the chevron-notched ones are less affected by FPZ and yield higher KIc results, providing that the loading method is the same. The notch types have little impact on the T-stresses of the specimens. This study sheds light on the combined influence of T-stress and FPZ on rock fracturing.

With access to the solution structures of nanocomposites of coordination nanocages (CNCs) via scattering and chromatography techniques, their mysterious solution dynamics have been, for the first time, resolved, and interestingly, the surface macromolecules can be substituted by extra free macromolecules in solutions. Obvious exchange of macromolecules can be observed in the solution mixtures of CNC nanocomposites at high temperatures, revising the understanding of the dynamics of CNC nanocomposites. Being distinct from nanocomposites of a simple coordination complex, the quantified solution dynamics of CNC nanocomposites indicates a typical logarithmic time dependence with the dissociation of surface macromolecules as the thermodynamically limiting step, suggesting strongly coupled and hierarchically constrained dynamics among the surface macromolecules. Their dynamics can be activated only upon application of high temperature or selected solvents, and therefore, the rational design of polymer assemblies, for example, hybrid-arm star polymers with precisely controlled compositions and reprocessable, robust CNC-cross-linked supramolecular polymer networks, is facilitated.

Ti3C2 is the first member of two-dimensional (2D) transition metal carbide or carbonitride (MXene) with excellent photothermal effect in disease treatment on an animal model, which shows a potential prospect on clinical application. However, in-depth details on the biosafety of MXene were insufficient. Metabolomics approach has offered an excellent alternative with numerous bioinformation, which can demonstrate the response of an organism to external stimuli at the molecular level. In this study, two different concentrations (100 and 500 mg/L) of MXene were used to treat human umbilical vein endothelial cells (HUVECs), and under both conditions, no obvious acute cytotoxicity was observed by cell proliferation and apoptosis measurement. We used a platform combining LC-MS/MS, GC-MS, and bioinformatics to analyze the changes of HUVECs metabolome after treatment with different concentrations of MXene, and the results indicated that —high concentrations (500 mg/L) of MXene can cause significant changes in the energy metabolism of HUVECs, showing obvious inhibition of tricarboxylic acid (TCA) cycle with the enhancement of glycolysis, fatty acid biosynthesis, and lipid accumulation, which are closely related to the functional disorder of mitochondria. The metabolomics results of the novel MXene-cell system extend the knowledge on the biological effect of MXene, possibly enabling technological innovations and material modifications.

Potassium ion batteries (KIBs) and potassium-based dual ion batteries (KDIBs) are newly-emerging energy storage devices that have attracted considerable attention owing to the low-cost of potassium resources and their comparable performance to lithium-ion batteries (LIBs). Graphite materials, as the successful commercialized anode materials of LIBs, can also be used as anodic and cathodic host materials for the intercalation of the large potassium cations and other anions, respectively. However, there are still some challenges hindering the practical application of graphite materials in the anode for KIBs and the cathode for KDIBs. The huge volume changes after intercalation (61% for K and 130% for anions) result in graphite interlayer slipping and structural collapse, causing capacity fade and a short cycle life. Moreover, the intercalation of large K+ and anions have poor kinetics due to the small graphite interlayer spacing, restricting the rate capability. To solve these issues of the use of graphite materials, this review attempts to provide a better understanding of the intercalation mechanisms for K+ and anions, and to correlate the electrochemical performance of KIBs and KDIBs to the microstructure of graphite, and the physicochemical properties of electrolytes and binders. Finally, research prospects are provided to guide the future development of graphite materials for potassium-based energy storage.

Rational designing and constructing multiphase hybrid electrode materials is an effective method to compensate for the performance defects of the single component. Based on this strategy, Cu2 Se hexagonal nanosheets@Co3 Se4 nanospheres mixed structures have been fabricated by a facile two-step hydrothermal method. Under the synergistic effect of the high ionic conductivity of Cu2 Se and the remarkable cycling stability of Co3 Se4 , Cu2 Se@Co3 Se4 can exhibit outstanding electrochemical performance as a novel electrode material. The as-prepared Cu2 Se@Co3 Se4 electrode displays high specific capacitance of 1005 F g-1 at 1 A g-1 with enhanced rate capability (56 % capacitance retention at 10 A g-1 ), and ultralong lifespan (94.2 % after 10 000 cycles at 20 A g-1 ). An asymmetric supercapacitor is assembled applying the Cu2 Se@Co3 Se4 as anode and graphene as cathode, which delivers a wide work potential window of 1.6 V, high energy density (30.9 Wh kg-1 at 0.74 kW kg-1 ), high power density (21.0 Wh kg-1 at 7.50 kW kg-1 ), and excellent cycling stability (85.8 % after 10 000 cycles at 10 A g-1 ).

Hydrogen has become a versatile and clean alternative to meet increasingly urgent energy demands since its high heating value and renewability. However, considering the hazards of hydrogen storage and transport, in-situ production processes are drawing more attention. Among all the hydrogen carriers, methanol has become one of the research focuses due to its high H/C ratio, flexibility and sustainability. Regarded as the core of hydrogen supply system, catalysts with higher activity, selectivity and stability are continuously developed for improved efficiency. In this review, two groups of catalysts were investigated namely copper-based and group VIII metal-based catalysts. Not only macro indicators such as feedstock conversion and product selectivity, but also micro interaction and reaction mechanism were elaborated, with respect to the effects of promoters, supports, synthesis methods and binary metal components. Notably, several reaction pathways and catalysts deactivation mechanisms were suggested based on this series of inspection of the structure-reactivity relationship, along with a general perception that large surface area, well dispersed metals, small particle size and synergy effects significantly improve the catalytic performance. Accordingly, a novel concept of single-atom catalysts (SACs) was introduced aimed at efficient hydrogen production under more moderate conditions, by combining the advantages of heterogeneous and homogeneous catalysis. Additionally, an efficient reforming process is required by properly regulating the feed flow and heat flow through a coupled system. Conclusively, a thorough supply and demand network of hydrogen based on methanol was presented, giving an overview for on-board applications of hydrogen energy.

New zircon U–Pb ages and whole-rock chemical data from four adakitic and two non-adakitic igneous rocks as tectonic blocks in the southern West Junggar accretionary complexes, northwestern China and one gabbro enclave in adakitic block provide further constraints on the initial subduction and following rollback process of the Junggar Ocean as part of southern Palaeo-Asian Ocean. The oldest adakitic monzonite in Tangbale is intruded by the non-adakitic quartz monzonite at 549 Ma, and the youngest adakitic diorite in Tierekehuola formed at 520 Ma. The Ediacaran–Cambrian magmatism show a N-wards younger trend. The high-SiO2 adakitic rocks have high Sr (300–663 ppm) and low Y (6.68–12.2 ppm), with Sr/Y = 40–84 and Mg no. = 46–60, whereas the non-adakitic rocks have high Y (13.2–22.7 ppm) and Yb (2.32–2.92 ppm), with Mg no. = 36–40. The gabbro has high MgO (14.81–15.11 wt%), Co (45–48 ppm), Cr (1120–1360 ppm) and Ni (231–288 ppm), with Mg no. = 72–73. All the samples show similar large-ion lithophile element (LILE) and light rare earth element (LREE) enrichment and Nb, Ta, Ti and varying Zr and Hf depletion, suggesting that they were formed in a subduction-related setting. The adakitic rocks were produced by partial melting of subducted oceanic slab, but the melts were modified by mantle wedge and slab-derived fluids; the non-adakitic rocks were likely derived from partial melts of the middle-lower arc crust; and the gabbro originated from the mantle wedge modified by slab-derived fluids. The magmatism could have been generated during the Ediacaran initial subduction and Cambrian slab rollback of the Junggar Ocean.

We present an ultra-compact single-shot spectrometer on silicon platform for sparse spectrum reconstruction. It consists of 32 stratified waveguide filters (SWFs) with diverse transmission spectra for sampling the unknown spectrum of the input signal and a specially designed ultra-compact structure for splitting the incident signal into those 32 filters with low power imbalance. Each SWF has a footprint less than 1 µm × 30 µm, while the 1 × 32 splitter and 32 filters in total occupy an area of about 35 µm × 260 µm, which to the best of our knowledge, is the smallest footprint spectrometer realized on silicon photonic platform. Experimental characteristics of the fabricated spectrometer demonstrate a broad operating bandwidth of 180 nm centered at 1550 nm and narrowband peaks with 0.45 nm Full-Width-Half-Maximum (FWHM) can be clearly resolved. This concept can also be implemented using other material platforms for operation in optical spectral bands of interest for various applications. Compact spectrometers that are simple and scalable in design can enable many applications. Here the authors demonstrate a silicon photonics based single-shot spectrometer that uses a group of waveguide frequency filters to construct the spectrum.

Zhenrui Xue,1– 3,* Minli You,2,3,* Ping Peng,1– 3,* Haoyang Tong,2,3 Wanghong He,2– 4 Ang Li,4 Ping Mao,1– 3 Ting Xu,1 Feng Xu,2,3 Chunyan Yao1 1Department of Transfusion Medicine, Southwest Hospital, Third Military Medical University, Army Medical University, Chongqing, 400038, People’s Republic of China; 2The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, 710049, People’s Republic of China; 3Bioinspired Engineering and Biomechanics Center (BEBC), Xi’an Jiaotong University, Xi’an, 710049, People’s Republic of China; 4Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an, 710049, People’s Republic of China*These authors contributed equally to this workCorrespondence: Chunyan Yao; Feng XuDepartment of Transfusion Medicine, Southwest Hospital, Third Military Medical University, Army Medical University, Chongqing, 400038, People’s Republic of ChinaTel +64 389 619 2922Email yao_yao24@yahoo.com; fengxu@mail.xjtu.edu.cnPurpose: Detection of single-base mutations is important for real-time monitoring of tumor progression, therapeutic effects, and drug resistance. However, the specific detection of single-base mutations from excessive wild-type background sequences with routine PCR technology remains challenging. Our objective is to develop a simple and highly specific qPCR-based single-base mutation detection method.Methods: Using EGRF T790M as a model, gold nanoparticles at different concentrations were separately added into the Taqman-MGB qPCR system to test specificity improvement, leading to the development of the optimal Taqman-MGB nanoPCR system. Then, these optimal conditions were used to test the range of improvement in the specificity of mutant-type and wild-type templates and the detection limit of mutation abundances in a spiked sample.Results: The Taqman-MGB nanoPCR was established based on the traditional qPCR, with significantly suppressed background noise and improved specificity for single-base mutation detection. With EGFR T790M as a template, we demonstrated that our Taqman-MGB nanoPCR system could improve specificity across a wide concentration range from 10− 9 μM to 10 μM and detect as low as 0.95% mutation abundance in spiked samples, which is lower than what the traditional Taqman-MGB qPCR and existing PCR methods can detect. Moreover, we also proposed an experimentally validated barrier hypothesis for the mechanism of improved specificity.Conclusion: The developed Taqman-MGB nanoPCR system could be a powerful tool for clinical single-base mutation detection.Keywords: nanoparticle-assisted PCR, point mutation, gold nanoparticle, specificity

Establishing how past climate change affected the stability of marine methane hydrate is important for our understanding of the impact of a future warmer world. As oceans shallow toward continental margins, the base of the hydrate stability zone also shallows, and this delineates the feather edge of marine methane hydrate. It is in these rarely documented settings that the base of the hydrate stability zone intersects the seabed and hydrate can crop out where it is close to being unstable and most susceptible to dissociation due to ocean warming. We show evidence for a seismically defined outcrop zone intersecting canyons on a canyon-incised margin offshore of Mauritania. We propose that climatic, and hence ocean, warming since the Last Glacial Maximum as well as lateral canyon migration, cutting, and filling caused multiple shifts of the hydrate stability field, and therefore hydrate instability and likely methane release into the ocean. This is particularly significant because the outcrop zone is longer on canyon-incised margins than on less bathymetrically complex submarine slopes. We propose considerably more hydrate will dissociate in these settings during future ocean warming, releasing methane into the world’s oceans.

The photocatalytic activity of metal–organic frameworks (MOFs) is closely related to the components and structures of metal oxo clusters. In this article, a gradient modulation of metal oxo cluster...

The invention of Transformer model structure boosts the performance of Neural Machine Translation (NMT) tasks to an unprecedented level. Many previous works have been done to make the Transformer model more execution-friendly on resource-constrained platforms. These researches can be categorized into three key fields: Model Pruning, Transfer Learning, and Efficient Transformer Variants. The family of model pruning methods are popular for their simplicity in practice and promising compression rate and have achieved great success in the field of convolution neural networks (CNNs) for many vision tasks. Nonetheless, previous Transformer pruning works did not perform a thorough model analysis and evaluation on each Transformer component on off-the-shelf mobile devices. In this work, we analyze and prune transformer models at the line-wise granularity and also implement our pruning method on real mobile platforms. We explore the properties of all Transformer components as well as their sparsity features, which are leveraged to guide Transformer model pruning. We name our whole Transformer analysis and pruning pipeline as TPrune. In TPrune, we first propose Block-wise Structured Sparsity Learning (BSSL) to analyze Transformer model property. Then, based on the characters derived from BSSL, we apply Structured Hoyer Square (SHS) to derive the final pruned models. Comparing with the state-of-the-art Transformer pruning methods, TPrune is able to achieve a higher model compression rate with less performance degradation. Experimental results show that our pruned models achieve 1.16×–1.92× speedup on mobile devices with 0%–8% BLEU score degradation compared with the original Transformer model.

Twin crystal structured Al-10 wt.% Mg alloys that were grown over a broad solidification velocity range were prepared and studied for the first time. The high thermal gradient (G) and growth velocity (V) of directional solidification resulted in the dominant solidification of twins: the twinned dendrite trunks at constant high Vs curved in the G direction with large angles in 7 mm diameter crucibles and invaded regular columnar grains because of a distinct kinetics growth advantage. Transitive deceleration experiments were designed to produce twin crystals that evolved with lower values of V (100, 10, and 0.5 μm/s) and had a structural coarsening trend. Twin cell growth in the absence of arms occurred at a growth velocity of 10 μm/s. A coherency loss was observed at a growth velocity of 0.5 μm/s with straight coherent twin boundaries turning into curved incoherent boundaries. Linear theoretical analyses were performed to understand the structural evolution of the twins. These results demonstrate the possibility of producing dense and controlled twin crystals in the Al-Mg system under most industrial production conditions; thus, this approach can be a new structural choice for designing Al-Mg-based alloys that have widespread commercial applications.

BMBWF (Austria); FWF (Austria)Austrian Science Fund (FWF); FNRS (Belgium)Fonds de la Recherche Scientifique - FNRS; FWO (Belgium)FWO; CNPq (Brazil)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ); CAPES (Brazil)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); FAPERJ (Brazil)Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio De Janeiro (FAPERJ); FAPERGS (Brazil)Fundacao de Amparo a Ciencia e Tecnologia do Estado do Rio Grande do Sul (FAPERGS); FAPESP (Brazil)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); MES (Bulgaria); CERN; CAS (China)Chinese Academy of Sciences; MoST (China)Ministry of Science and Technology, China; NSFC (China)National Natural Science Foundation of China (NSFC); COLCIENCIAS (Colombia)Departamento Administrativo de Ciencia, Tecnologia e Innovacion Colciencias; MSES (Croatia); CSF (Croatia); RIF (Cyprus); SENESCYT (Ecuador); MoER (Estonia); ERC PUT (Estonia); ERDF (Estonia); Academy of Finland (Finland)Academy of Finland; MEC (Finland); HIP (Finland); CEA (France)French Atomic Energy Commission; CNRS/IN2P3 (France)Centre National de la Recherche Scientifique (CNRS); BMBF (Germany)Federal Ministry of Education & Research (BMBF); DFG (Germany)German Research Foundation (DFG); HGF (Germany); GSRT (Greece)Greek Ministry of Development-GSRT; NKFIA (Hungary); DAE (India)Department of Atomic Energy (DAE); DST (India)Department of Science & Technology (India); IPM (Iran); SFI (Ireland)Science Foundation Ireland; INFN (Italy)Istituto Nazionale di Fisica Nucleare (INFN); MSIP (Republic of Korea); NRF (Republic of Korea); MES (Latvia); LAS (Lithuania); MOE (Malaysia); UM (Malaysia); BUAP (Mexico); CINVESTAV (Mexico); CONACYT (Mexico)Consejo Nacional de Ciencia y Tecnologia (CONACyT); LNS (Mexico); SEP (Mexico); UASLP-FAI (Mexico); MOS (Montenegro); MBIE (New Zealand); PAEC (Pakistan); MSHE (Poland); NSC (Poland); FCT (Portugal)Portuguese Foundation for Science and TechnologyEuropean Commission; JINR (Dubna); MON (Russia); RosAtom (Russia); RAS (Russia)Russian Academy of Sciences; RFBR (Russia)Russian Foundation for Basic Research (RFBR); NRC KI (Russia); MESTD (Serbia); SEIDI (Spain); CPAN (Spain); PCTI (Spain); FEDER (Spain)European Commission; MOSTR (Sri Lanka); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter (Thailand); IPST (Thailand); STAR (Thailand); NSTDA (Thailand); TUBITAK (Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); TAEK (Turkey)Ministry of Energy & Natural Resources - Turkey; NASU (Ukraine); STFC (U.K.)UK Research & Innovation (UKRI)Science & Technology Facilities Council (STFC); DOE (U.S.A.)United States Department of Energy (DOE); NSF (U.S.A.)National Science Foundation (NSF); Marie-Curie program (European Union); European Research Council (European Union)European Research Council (ERC)European Commission [675440, 724704, 752730, 765710]; Horizon 2020 Grant (European Union) [675440, 724704, 752730, 765710]; Leventis Foundation; A.P. Sloan FoundationAlfred P. Sloan Foundation; Alexander von Humboldt FoundationAlexander von Humboldt Foundation; Belgian Federal Science Policy OfficeBelgian Federal Science Policy OfficeEuropean Commission; Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium)Fonds de la Recherche Scientifique - FNRS; Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium)Institute for the Promotion of Innovation by Science and Technology in Flanders (IWT); F.R.S.-FNRS (Belgium) under the Excellence of Science -EOS -be.h projectFonds de la Recherche Scientifique - FNRS [30820817]; FWO (Belgium) under the Excellence of Science -EOS -be.h projectFWO [30820817]; Beijing Municipal Science & Technology CommissionBeijing Municipal Science & Technology Commission [Z191100007219010]; Ministry of Education, Youth and Sports (MEYS) of the Czech RepublicMinistry of Education, Youth & Sports - Czech Republic; Deutsche Forschungsgemeinschaft (DFG) under Germany's Excellence StrategyGerman Research Foundation (DFG) [EXC 2121, 390833306]; Lendulet (Momentum) Program of the Hungarian Academy of Sciences (Hungary); Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences (Hungary); New National Excellence Program UNKP (Hungary); NKFIA research grants (Hungary) [123842, 123959, 124845, 124850, 125105, 128713, 128786, 129058]; Council of Science and Industrial Research, IndiaCouncil of Scientific & Industrial Research (CSIR) - India; HOMING PLUS program of the Foundation for Polish Science (Poland); European Union, Regional Development Fund (Poland); Mobility Plus program of the Ministry of Science and Higher Education (Poland); National Science Center (Poland)National Science Centre, Poland [Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406]; National Priorities Research Program by Qatar National Research Fund; Ministry of Science and Higher Education (Russia) [02.a03.21.0005]; Tomsk Polytechnic University Competitiveness Enhancement Program; Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia Maria de Maeztu [MDM-2015-0509]; Programa Severo Ochoa del Principado de Asturias; Thalis program - EU-ESF; Aristeia program - EU-ESF; Greek NSRFGreek Ministry of Development-GSRT; Rachadapisek Sompot Fund for Postdoctoral Fellowship (Thailand); Chulalongkorn University (Thailand)Chulalongkorn University; Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); Kavli Foundation; Nvidia Corporation; SuperMicro Corporation; Welch FoundationThe Welch Foundation [C-1845]; Weston Havens Foundation (U.S.A.)

Aims Water and nitrogen (N) are two key resources in dryland ecosystems, but they may have complex interactive effects on the community structure and ecosystem functions. How future precipitation (rainfall vs snowfall) change will impact aboveground net primary production (ANPP) is far from clear, especially when combined with increasing N availability. Methods In this study, we investigated changes in community productivity, abundance and aboveground biomass of two dominant plant functional groups (PFGs), i.e. perennial rhizome grasses (PR) and perennial bunchgrasses (PB) under the impacts of increased precipitation (rainfall vs snowfall) combined with N addition in a semiarid temperate steppe. Important Findings Summer rainfall augmentation marginally increased community ANPP, whereas it significantly increased the abundance and aboveground biomass of PR, but not those of PB. Summer rainfall addition increased the fraction of PR biomass (fPR) while decreased that of PB (fPB). Spring snow addition had no effect on aboveground biomass of either compositional PFG although it marginally increased community ANPP. Nitrogen addition significantly increased community ANPP with greater increase in PR under summer rainfall addition, indicating strong interactive effects on community ANPP largely by enhancing PR biomass. We also found a nonlinear increase in the positive effect of nitrogen addition on productivity with the increased precipitation amount. These findings indicate an amplified impact of precipitation increase on grassland productivity under the accelerated atmospheric N deposition in the future.

(-)-Isoscopariusin A was isolated from the aerial parts of Isodon scoparius. Chemical synthesis and spectroscopic analysis established its structure as an unsymmetrical meroditerpenoid bearing a sterically congested 6/6/4 tricyclic carbon skeleton with seven continuous stereocenters. A gram-scale synthesis was achieved in 12 steps from commercially available (+)-sclareolide. A cobalt catalyzed, hydrogen atom transfer-based olefin isomerization was used to prepare a trisubstituted alkene, which underwent stereoselective [2+2] cycloaddition with a substituted keteniminium ion generated in situ from the corresponding amide. The cyclobutanone product was further elaborated into the fully substituted cyclobutane core through face-selective homologation, and the two side chains were installed by using nickel-catalyzed cross-electrophile coupling and carbodiimide-mediated esterification, respectively. (-)-Isoscopariusin A displayed selective inhibition of T-cell proliferation.

In this study, an experimental model about the coal gangue stockpiles in semi-open storage was developed. According to the model's requirements, the corresponding coal gangues were piled up in the factory building, the heat source and collection points were arranged, and the four operating temperatures were selected from 70 to 350 °C for heating. A series of fire experiments concerning the temperature distributions of the coal gangue piles were conducted systematically. The spontaneous combustion tendency of coal gangue samples under kinds of the four heat sources was analyzed using scanning electron microscope (SEM), thermal gravity analysis, and differential thermal gravity (TG-DTG). Under the action of thermal damage, the surface of micropores in coal gangue becomes rough. Heat accumulation is, in nature, most likely to occur near 0.1~0.4 m away from the heat source of coal pile. Simultaneously, on each of the measured flat layers, the greater the horizontal distance from the heat source is, the lower the heated temperature of gangues is, and the lower the temperature change rate is, indicating that the horizontal heat conduction is also gradually weakened. The experimental model provides an empirical basis for studying the distribution of temperature field in the depth of gangue pile and kinetics reaction mechanism of spontaneous combustion.

Purpose To describe the predisposing factors, presentation, management, and outcome of glaucoma drainage implant (GDI)-associated endophthalmitis. Design Retrospective chart review. Participants Eyes that developed GDI-associated endophthalmitis between December 1, 2011, and December 23, 2019, at the Duke Eye Center and Cole Eye Institute. Methods Patient data search was performed on the basis of diagnostic codes for GDI and endophthalmitis. Endophthalmitis was defined clinically according to each physician’s discretion. Eyes with infection source other than GDI were excluded. Worse vision was defined as a decrease of more than 2 Snellen lines. Data were collected on baseline demographics, systemic and ocular comorbidities, ocular surgical history, best-corrected visual acuity (BCVA), intraocular pressure (IOP), clinical presentation, eye culture results, and treatments performed. Statistical analysis included the paired t test and odds radio calculations. Main Outcome Measures Visual acuity and IOP at final follow-up. Results Thirty cases (0.7%) of GDI endophthalmitis were identified among 4073 GDIs performed at the 2 institutions with active follow-up. Device exposure was identified in 20 eyes (67%) on presentation. The average follow-up after presentation was 22.4 ± 25 months. The most frequently identified organism on culture was Streptococcus pneumoniae. Same-day injection of intravitreal antibiotics was the universal first-line therapy. From baseline to final follow-up, the mean BCVA decreased from −0.84 ± 0.77 to −1.30 ± 0.93 (logarithm of the minimum angle of resolution, P = 0.02). Mean IOP did not change from baseline to final visit in the overall cohort (16.2 ± 8.2 mmHg to 14.6 ± 9.4 mmHg, P = 0.30) and in the subgroup that underwent tube explant (15.9 ± 5.5 mmHg to 15.2 ± 10.4 mmHg, P = 0.97). Eighteen of 20 tube exposure cases (90%) underwent tube explant, 1 underwent tube revision, and 1 re-epithelialized. Conclusions Glaucoma drainage implant–associated endophthalmitis was correlated with poor visual outcome. Immediate intravitreal antibiotic delivery was a universal first-line therapy. Tube exposure was a necessary risk factor for late-onset endophthalmitis and required surgical removal or repair.

Purpose This study examined the effects of economic downturns at the time of graduation on short-term and long-term mental health of graduates. Methods Using a large longitudinal dataset whose respondents graduated from their highest level of education between 2001 and 2018 in Australia, the study investigated the effects of initial labor market conditions on psychological distress measures, quality-of-life mental health scales, and diagnoses of depression or anxiety since graduation. Results Evidence suggests the presence of a scarring effect of graduating during a recession on the mental health of young adults, particularly significant and persistent for men. Higher unemployment rates at graduation were associated with increased risks of high psychological distress and diagnoses of depression or anxiety, and lower levels of social functioning and mental well-being among men lasting over a decade. The psychological effect was largely driven by young adults with vocational or secondary qualifications or receiving no government allowance at graduation. Conclusions Policies should consider the psychological effect of graduating during recessions and focus particularly on vulnerable groups who are susceptible to adverse labor market conditions, such as graduates who are in cyclically sensitive occupations and have less or no work benefits and social protection.

The diversity of geological structure combinations in the coal seam floor makes it difficult to characterize, prevent and control floor water inrush in the Chenghe mining area in the Weibei coalfield, China. Based on a comparative study of the structure of the floor strata and the sedimentary characteristics of the no. 5 coal seam floor in the Chenghe mining area, the floor strata were categorized into four types. Fluid–solid coupling numerical simulation software was used to study floor water-blocking performance. We found that mining failure depth was the shallowest and water-blocking capacity was the best for the “soft-hard-soft” type of floor, followed by two interbeds of soft and hard type floors, while the mining failure depth was the deepest and the water-blocking capacity the worst for the “hard-soft-hard” type of floor. These conclusions were applied to guide the floor grouting reconstruction project at the 22,507 working face in the Dongjiahe coal mine. The “hard-soft-hard” type of floor was transformed into an "interbedded soft and hard" type of floor with a better water-blocking capacity, avoiding blind grouting, reducing grouting costs and the risk of water inrush, and allowing safe mining above the confined aquifer. The research results revealed how floor strata combinations control the water-blocking characteristics of the floor and provides scientific guidance for floor reinforcement and grouting projects.

The P-stereogenic phosphinamides are a structurally novel skeletal class which has not been investigated as chiral organocatalysts. However, chiral cyclic 3-hydroxy ketones are widely used as building blocks in the synthesis of natural products and bioactive compounds. However, general and practical methods for the synthesis of such chiral compounds remain underdeveloped. Herein, we demonstrate that the P-stereogenic phosphinamides are powerful organocatalysts for the desymmetric enantioselective reduction of cyclic 1,3-diketones, providing a useful method for the synthesis of chiral cyclic 3-hydroxy ketones. The protocol displays a broad substrate scope that is amenable to a series of cyclic 2,2-disubstituted five- and six-membered 1,3-diketones. The chiral cyclic 3-hydroxy ketone products bearing an all-carbon chiral quaternary center could be obtained with high enantioselectivities (up to 98% ee) and diastereoselectivities (up to 99:1 dr). Most importantly, the reactions could be practically performed on the gram scale and the catalysts could be reused without compromising the catalytic efficiency. Mechanistic studies revealed that an intermediate formed from P-stereogenic phosphinamide and catecholborane is the real catalytically active species. The results disclosed herein bode well for designing and developing other reactions using P-stereogenic phosphinamides as new organocatalysts.

We report an Ag1 single-atom catalyst (Ag1 /MnO2 ), which was synthesized from thermal transformation of Ag nanoparticles (NPs) and surface reconstruction of MnO2 . The evolution process of Ag NPs to single atoms is firstly revealed by various techniques, including in situ ETEM, in situ XRD and DFT calculations. The temperature-induced surface reconstruction process from the MnO2 (211) to (310) lattice plane is critical to firmly confine the existing surface of Ag single atoms; that is, the thermal treatment and surface reconstruction of MnO2 is the driving force for the formation of single Ag atoms. The as-obtained Ag1 /MnO2 achieved 95.7 % Faradic efficiency at -0.85 V vs. RHE, and coupled with long-term stability for electrochemical CO2 reduction reaction (CO2 RR). DFT calculations indicated single Ag sites possessed high electronic density close to Fermi Level and could act exclusively as the active sites in the CO2 RR. As a result, the Ag1 /MnO2 catalyst demonstrated remarkable performance for the CO2 RR, far surpassing the conventional Ag nanosized catalyst (AgNP /MnO2 ) and other reported Ag-based catalysts.

Drift of Quadrature operating point (Q-point) due to variations in ambient temperature restricts the demodulation accuracy of fiber-optic extrinsic Fabry-Perot interferometer (EFPI) sensors. To overcome this challenge, in this paper, we propose and demonstrate a self-stabilizing Q-point system based on Vernier-tuned distributed Bragg reflectors (VT-DBR) laser, the laser wavelength is locked to a point with the maximum slope on the interference spectrum of fiber-optic EFPI sensor. Taking advantage of large-tuning range (40nm) and fast wavelength switching capability (

Quantum computers promise to execute complex tasks exponentially faster than any possible classical computer, and thus spur breakthroughs in quantum chemistry, material science and machine learning. However, quantum computers require fast and selective control of large numbers of individual qubits while maintaining coherence. Qubits based on hole spins in one-dimensional germanium/silicon nanostructures are predicted to experience an exceptionally strong yet electrically tunable spin–orbit interaction, which allows us to optimize qubit performance by switching between distinct modes of ultrafast manipulation, long coherence and individual addressability. Here we used millivolt gate voltage changes to tune the Rabi frequency of a hole spin qubit in a germanium/silicon nanowire from 31 to 219 MHz, its driven coherence time between 7 and 59 ns, and its Lande g-factor from 0.83 to 1.27. We thus demonstrated spin–orbit switch functionality, with on/off ratios of roughly seven, which could be further increased through improved gate design. Finally, we used this control to optimize our qubit further and approach the strong driving regime, with spin-flipping times as short as ~1 ns. Quantum computing requires fast and selective control of a large number of individual qubits while maintaining coherence, which is hard to achieve concomitantly. All-electrical operation of a hole spin qubit in a Ge/Si nanowire demonstrates the principle of switching from a mode of selective and fast control to idling with increased coherence.

Water is a strategic and basic resource for industrial development. The efficient use of water resources is of great significance for the sustainable development of the economy and society. Dynamic SBM model could overcome the shortcomings of static models and reflect inter-temporal efficiency levels. The kernel density curve is used to fit the distribution pattern of industrial water use efficiency and describe its dynamic evolution. Empirical results show that from 2013 to 2017, under the meta-frontier, the industrial water use efficiency values of Beijing, Tianjin, Shandong, Inner Mongolia, and Shaanxi are all 1, and industrial water use efficiency is high, while the industrial water use efficiency values of Sichuan, Guizhou, Anhui, and other provinces are below 0.3, reflecting the low industrial water use efficiency. From 2013 to 2015, China's industrial water use efficiency generally shows a downward trend but begins to rise in the next 2 years. The kernel density curve generally exhibits a bimodal distribution trend and evolves from a "spike shape" to a "broad peak shape".

Thermochemical fuel reforming (TFR) is an innovative strategy in spark-ignition natural gas (NG) engines. According to this strategy, methane can be reformed into hydrogen and carbon monoxide with alcohol enrichment. In this study, effects of five kinds of alcohols on TFR were investigated. Differences of alcohols were classified into three parameters: OH/C ratio, hydroxyl numbers and isomerism, which were investigated in the laminar flow reactor platform. Experimental results demonstrated that methanol was regarded as the best enrichment fuel. Kinetic analysis indicated that alcoholic structure was strongly associated with concentrations of crucial radicals such as H, OH and HO2, which contributed to methane oxidation. Therefore, normal alkyl alcohols with less OH/C ratio and more hydroxyl numbers exhibited greater reactivity, which helped to the formation of CO and H2. Furthermore, this kinetic model was employed in engine simulations, and methanol has been proved to be a promising fuel for TFR engines.

Indoor location-based service is emerging as the crucial application of the Internet of Things, which promotes the advance of relevant technology in the indoor scenario. Several positioning algorithms are proposed for different indoor configurations in recent years. The fingerprint-based indoor positioning algorithm has drawn much attention because of the good positioning performance without additional hardware. However, the false fingerprint matching frequently incurs due to the complexity of the indoor positioning environment and affects the positioning accuracy. In this article, a principal component analysis (PCA)-assisted indoor positioning algorithm based on the adaptive hierarchical clustering algorithm (PAHC) is proposed, which can improve the positioning accuracy through aggregating the reference points (RPs) and conducting the cluster-based PCA (C-PCA) features extraction. More specifically, a clustering termination method is proposed to obtain reasonable RPs clusters adaptively according to the preset RPs. A two-stage fingerprint matching algorithm is proposed based on the C-PCA to further increase the difference between similar RPs and thus improving the positioning accuracy. To verify the proposed algorithm, an indoor wireless system is established in the practical indoor scenario. The experimental results indicate that the proposed PAHC algorithm can increase the positioning accuracy by 9.3% compared with the conventional fingerprint algorithm.

Porous carbon is usually used as an anode material for fast sodium storage due to its exceptional pore structure and high electrical conductivity. Herein, lithium hepta(i-butyl)silsesquioxane trisilanolate (T7-Li) is directly pyrolyzed to fabricate ultrathin porous carbon nanosheet 3D architectures (PCNS) via a novel “in situ dual templating” strategy. On one hand, the organic groups of T7-Li act as carbon sources for PCNS, and on the other hand, the pyrolysis of the inorganic core in T7-Li can generate both silica nanoparticles which act as a template for the formation of a porous structure, and most significantly, lithium silicate nanosheets formed by the reaction of silica and lithium oxide which serve as an inducer for the formation of carbon nanosheets. Impressively, when applied as the anode material for Na-ion batteries, PCNS delivers an ultrafast capacity of 230.5 mA h g−1 at 10 A g−1. Furthermore, the Na-ion capacitor assembled using PCNS as both the anode and cathode delivers an extremely high energy density of 137 W h kg−1 at 3454 W kg−1. This work proposes a novel strategy for the synthesis of porous carbon nanosheets for fast sodium storage and provides more possibilities to enrich the application of metallasilsesquioxanes.

Metal–organic framework (MOF)-derived carbon nanostructure photothermal materials have attracted tremendous attention, and have shown remarkable potential in the application of solar steam generation, due to their excellent light absorption properties, high chemical stability, and considerable photothermal conversion efficiency. In this paper, Cu-MOF derived carbon materials with regulable porous structures were prepared for the photothermal conversion application. It was found that the sample obtained at 500 °C shows the highest photothermal conversion efficiency as high as 64.42%. Besides, an efficient evaporator using polydimethylsiloxane as a matrix achieves an evaporation rate of 1.97 kg m−2 h−1 and a conversion efficiency of ca. 113.4% under one sun illumination. The effects of the compositions and structures of the materials on the photothermal conversion efficiency are also investigated, and the free radical concentration and the pore structures show a strong correlation with photothermal conversion efficiency.

Methanol-water reforming is a promising solution for H2 production/transportation in stationary and mobile hydrogen applications. Developing inexpensive catalysts with sufficiently high activity, selectivity, and stability remains challenging. In this paper, nickel-supported over face-centered cubic (fcc) phase α-MoC has been discovered to exhibit extraordinary hydrogen production activity in the aqueous-phase methanol reforming reaction. Under optimized condition, the hydrogen production rate of 2% Ni/α-MoC is about 6 times higher than that of conventional noble metal 2% Pt/Al2O3 catalyst. We demonstrate that Ni is atomically dispersed over α-MoC via carbon bridge bonds, forming a Ni1-Cx motif on the carbide surface. Such Ni1-Cx motifs can effectively stabilize the isolated Ni1 sites over the α-MoC substrate, rendering maximized active site density and high structural stability. In addition, the synergy between Ni1-Cx motif and α-MoC produces an active interfacial structure for water dissociation, methanol activation, and successive reforming processes with compatible activity.

The distribution pattern and genetic structure of plant species have been profoundly influenced by climate oscillations. Phylogeographic analyses have been numerously conducted in biodiversity hotspot regions and some general conclusions have been documented. However, other regions have received less attentions and these places may serve as potential glacial refugia for plant species to survive the Quaternary glaciation. Here, we used six nuclear and three cpDNA markers to estimate the phylogeographic pattern of

The increasing Internet-of-Things (IoT) devices have produced large volumes of data. A deep learning technique is widely used to analyze the potential value of these data due to its unprecedented performance in both the academic and industrial communities. However, the data generated from the IoT devices are distributed among different users. Directly combining these data to a central server will cause privacy leakage, especially for personal sensitive data. Rather than centralized training by getting access to all these raw data, an alternative is to collaboratively learn a model in a distributed manner. However, there exist two main challenges in a distributed learning setting. The first one is how to preserve the privacy of users. The second one is to reduce the communication burden (e.g., mobile users have limited bandwidth) due to high-frequent data exchange. To address these two challenges, we design a communication efficient and privacy-preserving framework to enable different participants to distributively learn a model with a privacy protection guarantee. In particular, we develop a differentially private approximate mechanism for the distributed deep learning. In addition, we design a new gradient sparsification method to, at the first time, reduce both upload and download communication costs. The performance of the proposed framework is tested under different neural network structures for different data sets including, image classification and mobile sensor data. The experimental results demonstrate that we can reduce the communication up to only 2% compared to the full gradients exchange and achieve up to 16% accuracy increase compared to the previous works.

Forest trees are an excellent resource from which to understand population differentiation and heterogeneous genome variation patterns due to the majority of forest trees being distributed widely and able to adapt to different climates and environments. Populus davidiana is among the most geographically widespread and ecologically important tree species in China. Whole‐genome resequencing data of 75 individual examples of P. davidiana throughout China were conducted, finding that all examples from different regions were clearly divided into either Northeast (N), Central (C), and South (S) populations. The ancestors of P. davidiana diverged into Northern group, comprising both N and C and Southern populations approximately 792,548 years ago. This time point of differentiation suggests that divergence of P. davidiana populations might have been triggered by the mid‐Pleistocene transition. The three populations experienced considerable periods of bottleneck following divergence, with population expansion beginning around 5,000 years ago after the end of the last glacial maximum. We found N to be the center of origin of P. davidiana in China. The migration route of P. davidiana in China was from N to S. Although the majority of the regions of genomic differentiation between N and S populations can be explained by neutral processes, a number of tested outlier regions were also found to have been significantly influenced by natural selection. Our results highlight that linked selection and rates of recombination were important factors in genomic differentiation between the N and S populations. Finally, we identified a substantial number of functional genes related to climate change during population differentiation and adaptive evolution.

Rocks in the deep underground are likely subjected to both hydrostatic confining pressure and dynamic compression–shear load. Thus, accurately characterizing the dynamic properties and failure mechanism of hydrostatically confined rocks under combined compression–shear impacting is crucial for the stability assessment of deep underground rock structures. In this study, on the basis of an improved split Hopkinson pressure bar (SHPB) apparatus, the combined dynamic compression–shear tests are performed on inclined cylindrical sandstone specimens with hydrostatic confining pressures. During the test, the dynamic force balance of rock specimens can be well satisfied using the pulse shaping technique. Our results show that the hydrostatic confining pressure and dynamic loading rate help strengthen the load-carrying capacity of rocks. In contrast, the shear component in the dynamic load limits the dynamic peak stress of rocks. As hydrostatic confining pressure increases, the failure surface based on the Drucker–Prager criterion gradually expands outward. Under dynamic loading, the compressive deformation modulus of rocks decreases with increasing shear component in the dynamic load, contrary to its response to hydrostatic confining pressure. Fragmentation analysis indicates that the hydrostatic confining pressure and the shear component of dynamic loading restrict the fracture behavior of rocks. Besides, as the specimen inclination angle and the hydrostatic confining pressure increase, the failure pattern of rock specimens changes from the tensile-dominated failure with a truncated conical surface to the shear-dominated failure with a single shear plane along its short diagonal.

The microbial flocculant (MFX) extracted from Klebsiella pneumoniae J1 was used to remove carbamazepine in prepared wastewater and domestic sewage. The influence factors and flocculation mechanism were studied. The optimal carbamazepine removal conditions for MFX were pH of 7-8, 7 mL of flocculant, 0.1 mL of coagulant, and 35°C, and the removal rate reached 81.75%. MFX was efficient in the removal of carbamazepine in both domestic sewage (75.03%) and secondary sedimentation tank effluent (69.76%). The pseudo-first-order kinetic equation fitted the adsorption process better than the pseudo-second-order kinetic equation, which suggested that the adsorption was not pure chemical adsorption. The analysis of floc size suggested that the repulsive force between carbamazepine and MFX was weakened under alkalescent conditions, which can help the growth and coherence of flocs and increase the carbamazepine removal efficiency. Enough dosage of MFX can generate larger flocs, but excessive dosage of MFX will decrease the carbamazepine removal rate because of increase in electrostatic repulsion. The analysis of 3D-EEM and FTIR suggested that hydroxyl, amino, and carboxyl in MFX played an important role in the removal of carbamazepine. As an eco-friendly and highly efficient microbial flocculant, MFX has potential for practical applications in carbamazepine removal.

Mobile differential optical absorption spectroscopy (mobile DOAS) has become an important tool for the quantification of emission sources, including point sources (e.g., individual power plants) and area emitters (e.g., entire cities). In this study, we focused on the error budget of mobile DOAS measurements from point sources, and we also offered recommendations for the optimum settings of such measurements via a simulation with a modified Gaussian plume model. Following the analysis, we conclude that (1) the proper sampling resolution should be between 5 and 50 m. (2) When measuring far from the source, undetectable flux (measured slant column densities (SCDs) are under the detection limit) resulting from wind dispersion is the main error source. The threshold for the undetectable flux can be lowered by larger integration time. When measuring close to the source, low sampling frequency results in large errors, and wind field uncertainty becomes the main error source of SO2 flux (for NOx this error also increases, but other error sources dominate). More measurement times can lower the flux error that results from wind field uncertainty. The proper wind speed for mobile DOAS measurements is between 1 and 4 m s−1. (3) The remaining errors by [NOx] ∕ [NO2] ratio correction can be significant when measuring very close. To minimize the [NOx] ∕ [NO2] ratio correction error, we recommend minimum distances from the source, at which 5 % of the NO2 maximum reaction rate is reached and thus NOx steady state can be assumed. (4) Our study suggests that emission rates

Previous studies reported that the differences in the toxicity of reduced graphene oxide (rGO) modified by metal nanoparticles (NPs) were mainly caused by the released metal ions, while the impact of cell surface properties and rGO nanocomposites characteristics on the toxic effects have seldom been taken into consideration. In this study, we investigated the toxicities of six rGO nanocomposites (rGO-Au, rGO-Ag, rGO-Pd, rGO-Fe3O4, rGO-Co3O4, rGO-SnO2) in two algae (Scenedesmus obliquus and Chlamydomonas reinhardtii) with the aim of evaluating the role of surface properties on the different toxic effects. Results showed that C. reinhardtii was sensitive to the rGO nanocomposite, but no obvious adverse effect was observed in S. obliquus. Moreover, different rGO nanocomposites showed various toxic effects in C. reinhardtii. Properties including algal cell surface and rGO nanocomposites were then characterized. Cells with abundant functional groups and hydrophobic surfaces exhibited more metal adsorption and interactions with the nanomaterials. In addition, heterointerfaces and released ions from rGO nanocomposites triggered various toxicities by interfering with the interactions with algal cells. However, algal surface properties were the main factors determining the different toxic effects between algal species. This study emphasizes the importance of surface properties in the process of toxicity evaluation.

Ordovician limestone water on the floor is a serious threat to the safety of coal mine production in the Weibei coalfield, and prediction of the floor failure depth is the key for evaluating the mining conditions under pressure. This paper combines the hydrogeological conditions of the no. 5 coal seam and uses the FLAC3D program to determine the floor failure depth under two-factor (mining depth and width) and multifactor (mining depth, width, and height) conditions via numerical calculations and analysis. We obtain the fitting formula for the floor failure depth and analyze the influence of various factors on it. The results show that when the mining width does not exceed 200 m, the mining width has the greatest influence on the floor failure depth, followed by mining depth and mining height. In this paper, the working face floor failure depths measured values of 18 flat seams in China are taken as samples for comparison with the values calculated via empirical formulas and fitting formulas, and the maximum and minimum absolute errors and relative errors are analyzed. The nonlinear fitting regression formulas offered in this paper are found to provide strong predictive value, high accuracy, and a relatively small error range. The reliability and rationality of the models are further verified, thus providing a reference for future mining operations under safe aquifer water pressure conditions in the Weibei coalfield.

Large-bore low-speed two-stroke dual fuel engines have become an urgent need to relieve energy crisis and reduce emissions. In this study, the effects of fuel reforming on large-bore low-speed two-stroke dual fuel marine engine combined with EGR and injection strategy were investigated. With increase of injection advance angle, the ISFC increases slightly, and also NOx emissions increase, which indicate that the optimal injection timing is 12.5°CA BTDC in consideration of emission and fuel economy. A 10% EGR rate is selected for NOx reduction and pressure rise rate suppression, which might increase fuel consumption in lower combustion temperature. Subsequently, fuel reforming is applied for further fuel consumption optimization. Compared with the base case, ISFC is reduced by 7.80% by introducing 1.29% syngas, but NOx emissions are higher than IMO Tier Ⅲ limit emissions standards. After combined optimization, the indicated thermal efficiency could be increased from nearly 50% (base case) to 55% by 12.5 BTDC_E10_2.25% (pilot fuel injection timing is 12.5°CA BTDC, EGR rate is 10%, and γreforming is 2.25%). Compared with the base case, the NOx emissions increase, but still lower than the limit value of IMO Tier Ⅲ emission standards, while the ISFC reduce 9.45% by 12.5 BTDC_E10_2.25%. Base on the above discussion, it can be concluded that the collaborative strategy has great potential in improving the fuel economy and also controlling emissions standard of low-speed dual fuel marine engine.

This paper addresses the problem of adaptive sliding mode attitude tracking control for a class of nonlinear flexible spacecraft systems with a redundant four reaction wheels’ setting and unknown actuator dead-zone, where configuration misalignment and external disturbance are considered simultaneously. By using the Takagi-Sugeno (T-S) fuzzy modelling method, the overall nonlinear spacecraft attitude dynamics system is first reconstructed into several local linear systems. Then, an adaptive integral-type sliding mode control scheme is introduced based on a T-S fuzzy model to stabilize the considered attitude tracking control system of flexible spacecraft. In this design, the external disturbance with unknown bound is counteracted in real-time by the adaptive estimate technique. Additionally, the integral sliding surface we introduced is insured to be asymptotically stable under the condition of given matrix inequality. The proposed adaptive sliding mode controller guarantees the finite-time reachability of the specific sliding surface. A practical example with simulation results is given to verify the validity of the attitude tracking control strategy we put forward.

The booming prosperity of strain sensors promotes the regeneration of wearable electronics. However, strain sensors featured with both large workable range and superb sensitivity are still less than satisfaction. Softness and practicality are also of vital importance for wearable electronics. In this work, a flexible wearable strain sensor based on carbonized cotton fabric coated with reduced graphene oxide (rGO) through polydopamine (rGO/PDA/CCF) modification was fabricated, which exhibits fascinating electrical mechanical performance including a large workable range and superb sensitivity. rGO/PDA/CCF was characterized using scanning electron microscopy (SEM), Raman scattering spectroscopy, and X-ray diffraction (XRD) patterns. The electromechanical performance of the rGO/PDA/CCF strain sensor was evaluated. The strain sensors of rGO/PDA/CCF exhibit a large workable strain range (0–120%) and superb sensitivity with strong durability over 800 cycles. The rGO/PDA/CCF strain sensor has a low detection limit down to 0.01% with a good gauge factor (GF) of 132 within the strain range of 0–1%, and also displays fantastic property in terms of sensitivity in other workable range (GF of 26 and 8 within in a strain range of 1–30% and 30–60%, respectively). rGO/PDA/CCF strain sensor was then applied to track the signal of human motions in real time. rGO/PDA/CCF flexible strain sensor can be utilized in detecting almost all human motions with various dimensions. Additionally, the hydrophobicity and the stability at different temperatures endow the rGO/PDA/CCF strain sensor with high efficiency in various usage, which shows its potential for application in health monitor and wearable electronics.

Slope stability analysis is a core issue in geotechnical engineering. This paper proposes a method of upper bound limit stability analysis for a slope with multiparameter coordinated variation based on the comprehensive consideration of the nonuniform distribution of slope soil parameters. This method starts from the perspective of energy balance, establishes a slope failure mechanism which meets velocity separation requirements, deduces its calculation formula for external force power and internal energy dissipation power, develops a cycle program for the most dangerous slip surface searching and stability coefficient calculation through computer programming technology, and finally forms a calculation method of upper bound limit stability analysis for the soil slope with nonuniform multiparameter distribution. At the same time, this method takes a dump slope in an open-pit mine as the engineering background, considers the nonuniformity of density, cohesion, and internal friction angle of the slope soil under subsidence, applies upper bound limit analysis to analyze the slope stability, and evaluates the accuracy of analysis results by using the residual thrust method. The results show that upper bound limit analysis has highly accuracy in stability coefficient calculation; compared with the residual thrust method, the stability coefficient calculation result by upper bound limit analysis is a strict upper bound solution, and the calculation error is easy to be estimated and eliminated. Simultaneously, the most dangerous slip surface obtained by upper bound limit analysis can fully satisfy the velocity separation requirement and has a greater engineering reference value.

All-inorganic zero-dimensional (0D) tetrahedrite (Cu12Sb4S13, CAS) quantum dots (QDs) have attracted extensive attention due to their excellent optical properties, bandgap tunability, and carrier mobility. In this paper, various sized CAS QDs (5.1, 6.7, and 7.9 nm) are applied as a switching layer with the structure F:SnO2 (FTO)/CAS QDs/Au, and in doing so, the nonvolatile resistive-switching behavior of electronics based on CAS QDs is reported. The SET/RESET voltage tunability with size dependency is observed for memory devices based on CAS QDs for the first time. Results suggest that differently sized CAS QDs result in different band structures and the regulation of the SET/RESET voltage occurs simply and effectively due to the uniform size of the CAS QDs. Moreover, the presented memory devices have reliable bipolar resistive-switching properties, a resistance (ON/OFF) ratio larger than 104, high reproducibility, and good data retention ability. After 1.4 ×106 s of stability testing and 104 cycles of quick read tests, the change rate of the ON/OFF ratio is smaller than 0.1%. Furthermore, resistive-witching stability can be improved by ensuring a uniform particle size for the CAS QDs. The theoretical calculations suggest that the space-charge-limited currents (SCLCs), which are functioned by Cu 3d, Cu 3p and S 3p to act as electron self-trapping centers due to their quantum confinement and form conduction pathways under an electric field, are responsible for the resistive-switching effect. This paper demonstrates that CAS QDs are promising as a novel resistive-switching material in memory devices and can be used to facilitate the application of next-generation nonvolatile memory.

Understanding the ecology and sustainability of the Inner Mongolian Grassland is crucial for improving land management policies in the Mongolian Plateau and beyond. However, a systematic and comprehensive review of the relevant literature is still lacking. This review was intended to: (1) assess the current state of the ecological and sustainability research of the Inner Mongolian Grassland region, and (2) identify critical research topics and challenges for understanding pathways to sustainability of the region. We conducted a bibliometric analysis of 2571 English articles indexed in the Web of Science during 1998–2019. Multiple methods, including descriptive statistics, principal component analysis, change point detection, theme mining, and association strength analysis, were combined to analyze the sampled literature. All reviewed studies can be grouped into four types: description of ecological and biogeochemical characteristics of degraded grasslands (type I), the impacts of climate change and human activities on aboveground (type II) and belowground grassland ecosystem functioning (type III), and the impacts of different management strategies on grassland ecosystem services and human well-being (type IV). The number of publications in all four themes has rapidly increased after 2007–2009. The four types of articles were related to each other in terms of the interannual publication consistency. Keyword co-occurrence network analysis showed that climate change and grazing were the major research topics, which are closely related to all other topics. Three perspectives have persisted in the ecology and sustainability research of the Inner Mongolian Grassland: Ecology in the Grassland, Ecology of the Grassland, and Sustainability of the Grassland. Based on the emerging landscape sustainability science framework, the transdisciplinary approach to landscape sustainability diagnostics and landscape planning and design should become a priority in advancing sustainability research of the region.

A series of heteropoly acid (HPA) based Al2O3 catalysts with three-dimensional ordered (3DOM) structure were synthesized by colloidal crystal template method. Interconnected macropores (250 nm) could be clearly observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Mesopores could be detected by N2 adsorption-desorption isotherms which further confirmed the 3DOM structural characteristics of catalyst. Moreover, Keggin-type HPW was highly dispersed in the Al2O3 framework, which suggested by powder X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR) results. The oxidation desulfurization (ODS) performance of 3DOM H3PW12O40/Al2O3 of refractory sulphur compounds was evaluated in the presence of hydrogen peroxide. It oxidized 98.5% of dibenzothiophene (DBT) into corresponding sulfone within 3 h, which exhibited superior ODS performance than corresponding mesoporous and microporous H3PW12O40/Al2O3 catalyst. The enhancement of ODS efficiency is related to the improvement of mass transfer of DBT in the pore channel resulting from the interconnected 3DOM structure. Furthermore, the as-prepared catalyst still demonstrates outstanding cycle performance after 6 runs, which could be easily recovered from the model fuel.