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The incorporation of P into Pt–Co nanoalloys is used to regulate the electron density around Pt for high-efficiency methanol electrooxidation.

Developing affordable and efficient electrocatalysts as precious metal alternatives toward the hydrogen evolution reaction (HER) is crucially essential for the substantial progress of sustainable H2 energy-related technologies. The dual manipulation of coordination chemistry and geometric configuration for single-atom catalysts (SACs) has emerged as a powerful strategy to surmount the thermodynamic and kinetic dilemmas for high-efficiency electrocatalysis. We herein rationally designed N-doped multichannel carbon nanofibers supporting atomically dispersed Mo sites coordinated with C, N, and O triple components (labeled as Mo@NMCNFs hereafter) as a superior HER electrocatalyst. Systematic characterizations revealed that the local coordination microenvironment of Mo is determined to be a Mo-O1N1C2 moiety, which was theoretically probed to be the energetically favorable configuration for H intermediate adsorption by density functional theory calculations. Structurally, the multichannel porous carbon nanofibers with open ends could effectively enlarge the exposure of active sites, facilitate mass diffusion/charge transfer, and accelerate H2 release, leading to promoted reaction kinetics. Consequently, the optimized Mo@NMCNFs exhibited superior Pt-like HER performance in 0.5 M H2SO4 electrolyte with an overpotential of 66 mV at 10 mA cm-2, a Tafel slope of 48.9 mV dec-1, and excellent stability, outperforming a vast majority of the previously reported nonprecious HER electrocatalysts. The concept of both geometric and electronic engineering of SACs in this work may provide guidance for the design of high-efficiency molecule-like heterogeneous catalysts for a myriad of energy technologies.

Mapping the crop type can provide a basis for extracting information on crop planting structure, and area and yield estimation. Obtaining large-scale crop-type mapping by field investigation is inefficient and expensive. Traditional classification methods have low classification accuracy due to the fragmentation and heterogeneity of crop planting. However, the deep learning algorithm has a strong feature extraction ability and can effectively identify and classify crop types. This study uses GF-1 high-resolution remote sensing images as the data source for the Shuangcheng district, Harbin city, Heilongjiang Province, China. Two spectral feature data sets are constructed through field sampling and employed for training and verification, combined with basic survey data of grain production functional areas at the plot scale. Traditional machine learning algorithms, such as random forest (RF) and support vector machine (SVM), and a popular deep learning algorithm, convolution neural network have been utilized. The results show that the fusion of multi-spectral information and vegetation index features helps improve classification accuracy. The deep learning algorithm is superior to the machine learning algorithm in both classification accuracy and classification effect. The highest classification accuracy of Crop Segmentation Network (CSNet) based on fine-tuning Resnet-50 is 91.2%, kappa coefficient is 0.882, and mean intersection over union is 0.834. The classification accuracy is 13.3% and 9.5% points higher than RF and SVM, respectively, and the best classification performance is obtained. The classification accuracy and execution efficiency of the model are suitable for a wide range of crop classification tasks and exhibit good transferability.

Heterogeneous nanocomposites comprising chemically distinct constituents are particularly promising in electrocatalysis. We herein report a synthetic strategy that combines the reduction of Pt and Co ionic precursors at an appropriate ratio with the subsequent phosphating at an elevated temperature for forming heterogeneous nanocomposites consisting of quasi‐spherical Pt3Co alloy domains and rod‐like CoP2 domains for high‐efficiency methanol electro‐oxidation. The strong electronic coupling between Pt3Co and CoP2 domains in the nanocomposites render the electron density around Pt atoms to decrease, which is favorable for reducing the adsorption of poisoning CO‐like intermediates on the catalyst surfaces. Accordingly, the as‐prepared heterogeneous Pt3Co–CoP2 nanocomposites show good performance for methanol electro‐oxidation both in acidic and alkaline media. In specific, at a Pt loading of only 6.4% on a common carbon substrate, the mass‐based activity of Pt3Co–CoP2 nanocomposites in an acidic medium is about 2 and 1.5 times as high as that of commercial Pt/C catalyst (20% mass loading) and home‐made Pt3Co alloy nanoparticles (8.0% mass loading), while in the alkaline medium, these values are 3 and 2, respectively.

Relying on the resource-based view, this study tests the moderating effects of the region’s institutional development and the firm’s IT (information technology) infrastructure capability, and examine how and when interpersonal and government-firm (GF) guanxi influence the distributor’s opportunism and cooperative performance. Using both survey data from 550 industrial manufacturers and secondary data, the study shows that both types of guanxi can mitigate the distributor’s opportunism and facilitate cooperative performance. However, the region’s institutional development strengthens the effects of interpersonal guanxi while weakening the effects of GF guanxi, and the firm’s IT infrastructure capability weakens the effects of interpersonal guanxi while strengthening the effects of GF guanxi. These findings enrich both the literature on guanxi in the emerging economy by distinguishing two types of guanxi and RBV by testing the moderating effects of institutional development and IT infrastructure capability. Theoretical and practical implications are discussed.

Specific chemical reactions only happen in the tumor region and produce abundant special chemicals to in situ trigger a train of biological and pathological effects that may enable tumor-specific curative effects to treat cancer without causing serious side effects on normal cells or organs. Chemodynamic therapy (CDT) is a rising tactic for cancer therapy, which induces cancer cell death via a localized Fenton reaction. However, the tumor therapeutic effect is limited by the efficiency of the chemical reaction and relies heavily on the catalyst. Here, we constructed hollow porous carbon coated FeS2 (HPFeS2@C)-based nanocatalysts for triple-enhanced CDT. Tannic acid was encapsulated in HPFeS2@C for reducing Fe3+ to Fe2+, which had a better catalytic activity to accelerate the Fenton reaction. Afterward, glucose oxidase (GOx) in nanocatalysts could consume glucose in the tumor microenvironment and in situ synchronously produce H2O2, which could improve Fenton reaction efficiency. Meanwhile, the consumption of glucose could lead to the starvation effect for cancer starvation therapy. The photothermal effects of HPFeS2@C could generate heat, which further sped up the Fenton process and implemented synergetic photothermal therapy/starvation therapy/CDT. The biodistribution of nanoparticles was investigated by multimodal magnetic resonance, ultrasound, and photoacoustic imaging. These nanocatalysts could trigger the catalytic Fenton reaction at a high degree, which might provide a good paradigm for nanocatalytic tumor therapy.

One of the advantages of Arctic shipping or the Northern Sea Route (NSR) over the traditional Suez Canal Route (SCR) is its comparatively shorter transport distance between the Atlantic and the Pacific, which makes North East Asia and North Europe seemingly closer geographically and economically. The economic development of the North-East Asia brings further potential for the commercial applications of the NSR. Meanwhile, China's "Belt and Road" Initiative (BRI), the Railway Transport between China and Europe (Railway) has also been developing rapidly. This has led to the possibility of route competition among the NSR, the SCR and the Railway in freight transport between East Asia and Western Europe. In this paper, the market shares of the three transport routes are analyzed using bootstrapped multinomial logit (MNL) model. Further, scenario analysis is provided to examine the change of market share of the NSR under varying development trends related to economic conditions, natural conditions, and shippers' preference. Based on the results, policy implications and suggestions are discussed.

Chemotherapy resistance hinders the successful clinical cancer therapy, because of the low sensitivity of drugs to resistant cancer cells. In resistant cancer cells, the mutant p53 possesses anti-apoptosis capability to tolerate chemotherapeutic drugs such as doxorubicin (DOX). Phenethyl isothiocyanate (PEITC) derived from cruciferous vegetables can deplete intracellular mutant p53. In this work, the black phosphorus nanosheets-based (BPNs-based) drug delivery system integrated with PEITC can effectively decrease mutant p53 level in resistant cancer cells and realize multiple drug resistance (MDR) reversal. The intrinsic properties of BPNs could achieve synergistic photothermal/photodynamic/chemo-therapy of resistant cancer. Magnetic resonance imaging (MRI) is used to investigate the biodistribution of nanoparticles which confirmed the efficient accumulations of nanoparticles at tumor sites. In vitro and in vivo anticancer experiments demonstrate the drug resistance tumor is effectively inhibited with minimal side effects by BPNs-based drug delivery system.

With the progress of the times, the development of science and technology, the deepening of research in various fields, and the accuracy requirements for DEM are becoming higher and higher, and the DEM of satellite image interpretation has become more and more unable to meet the needs of research. UAV photogrammetry, as a new aerial survey and monitoring method, has the characteristics of high precision, low cost and fast renewal, which can make up for the shortcomings of traditional means in topographic survey. This paper takes the Wuyiling Nature Reserve as the research object, uses the UAV photogrammetry technology combined with the improved progressive triangular mesh filtering algorithm to extract the DEM, obtains the resolution 0.5 m terrain data, and evaluates it. The result verification shows that the precision DEM constructed by progressive triangulation encryption filtering based on region segmentation can display the terrain information more intensively; especially for high-vegetation area, high-resolution DEM can be generated to reflect the real surface condition.

Specific chemical reactions only happen in the tumor region and produce abundant special chemicals to in situ trigger a train of biological and pathological effects that may enable tumor-specific curative effects to treat cancer without causing serious side effects on normal cells or organs. Chemodynamic therapy (CDT) is a rising tactic for cancer therapy, which induces cancer cell death via a localized Fenton reaction. However, the tumor therapeutic effect is limited by the efficiency of the chemical reaction and relies heavily on the catalyst. Here, we constructed hollow porous carbon coated FeS

Depiction of the patterns and underlying processes within communities is a key topic in community ecology. However, we still know relatively little about these patterns and processes for the dominant arthropod communities living in above-ground (AG) and below-ground (BG) ecosystems. To test whether the community patterns for AG communities are consistent with those of BG communities and to inform whether the underlying processes are congruous, samples of ground carabid and soil collembolan communities were collected from a primary mixed forest in Northeastern China. Within a 9-ha permanent forest plot, 225 carabid samples were captured using pitfall traps in August 2015, and 768 collembolan samples were collected using soil augers in September 2014. Vegetative, topographic, soil and spatial variables were also measured. Geostatistics, null models and variation partitioning were used to evaluate the spatial distributions, co-occurrence patterns and contributions of environmental and spatial factors, respectively. The carabid community did not show obvious spatial autocorrelation, while the collembolan community showed significant spatial autocorrelation and aggregation on multiple spatial scales. Both communities showed non-random co-occurrence patterns, but of different types. The carabid community was driven by weak and insignificant topographic filtering, while the collembolan community was driven by strong and significant topographic filtering. The two communities were each shaped by spatial factors, but the carabid community’s spatial distribution may be regulated by their high dispersal ability, which allowed the beetles to overcome topographic constraints. On the other hand, the collembolan community’s spatial distribution may be regulated by their dispersal limitations, which combine with topographic constraints to create an aggregation pattern. Finally, we conclude that the dominant AG and BG arthropod communities exhibit different community structure patterns controlled different spatial processes.

Electronic regulation via interfacial engineering is a versatile strategy to boost the efficiency of earth-abundant electrocatalysts for the oxygen evolution reaction (OER). Herein, we demonstrate the combination of interfacial manipulation with nanoarchitectonics by elaborately designing Janus-structured NiS/NiO nanoparticles in-situ encapsulated within N-doped carbon nanotube “branches”/nanofiber “trunk”-typed superstructures (abbreviated as NiS/NiO@N-C NT/NFs hereafter) to effectively regulate the electronic configuration for expediating the OER process. The simultaneous realization of interfacial engineering and nanoarchitectonics renders the resultant NiS/NiO@N-C NT/NFs with optimized electronic configuration, increased oxygen vacancies, promoted mass diffusion channels and remarkable structural robustness. Therefore, the NiS/NiO@N-C NT/NFs exhibit outstanding OER activity with a small overpotential of 269 mV at 10 mA cm−2 and impressive long-term stability in alkaline electrolyte, representing an economical and competetive electrocatalyst for a number of sustainable energy devices. Density functional theory (DFT) simulations further validate that the formation of NiS/NiO heterojunction effectively tailors the chemisorption energies of the oxygen-related intermediates and reduces the reaction barrier, drastically accelating the OER kinetics. These findings demonstrating the significance of interface manipulation and hybridization with nanocarbon may offer a novel perspective for rational design of high-performance electrocatalysts towards the energy storage and conversion.

Biotic interactions are an important factor in determining community composition. However, spatial and coexistence patterns and species associations within a trophic group remain unclear, particularly for belowground ecosystems. We tested the hypothesis that the spatial patterns, coexistence patterns and species associations would be negative for ground carrion beetles (Coleoptera: Silphidae) at a small scale and that negative species associations would be stronger within a subfamily than between different subfamilies. To test this hypothesis, ground carrion beetles were collected from two permanent plots (each 300 × 300 m) within a mixed broad-leaved Korean pine forest in northeastern China and separated into the subfamilies Nicrophorinae and Silphinae. Geostatistical methods were used to evaluate the spatial patterns and spatial species associations. Null model analyses were performed to examine the coexistence patterns and coexisting species associations. Overall, most communities and species populations were positively spatially autocorrelated at multiple scales. Moreover, spatial patterns of all communities and most species populations were non-randomly aggregated, and most coexisting patterns of communities were also non-random. Furthermore, most spatial species associations were positive, with only a small number of nonsignificant negative spatial species associations observed between Nicrophorinae species. All coexisting species associations that were significant occurred only within the same subfamily. Notably, all significant spatial and coexisting species associations were positive. Based on this study, negative spatial and coexistence patterns and species associations are uncommon for carrion beetles at a small scale, and the only significant positive associations were within the same subfamily.

Using the survey and secondary data of Chinese manufacturers, this study assesses whether and how channel diversification affects hybrid channel conflict, as well as the moderating role of IT resou...

With the development of science and technology in recent years, concepts such as big data and databases frequently appear in people’s fields of vision. Among them, big data and the construction of foreign language corpora have become common practice in the field of academic research. It has a certain understanding by consulting related journals, papers and books. This article starts with what big data is, what it means to build a corpus for linguistic research, and the situation of linguistic research in the context of big data, and briefly explains the current status of data and linguistic research in the context of big data discussion and at the same time hopes to have a more comprehensive understanding and understanding of the database.

Several models have been employed in the past to estimate interfacial thermal conductance (ITC) for different material interfaces, of which the diffuse mismatch model (DMM) has been generally accepted as reliable for rough material interfaces at high temperature. Even though the DMM has been shown to predict the correct order of magnitude in isotropic material interfaces, it is unable to reproduce the same accuracy for low-dimensional anisotropic layered materials, which have many potential applications. Furthermore, the use of approximated dispersion curves tends to overestimate the ITC. In this work, we propose a new method that utilizes a mode-to-mode comparison within the DMM framework to predict ITC. We employed this model to calculate ITC between layered materials such as MoS2 and graphite and metals such as Al, Au, and Cr. We then compared our values with previous literature data that employ linear dispersion relations and experimental data from time-domain thermoreflectance measurements. This new framework was then used to visualize the phonon focusing effect in anisotropic materials. Further analysis revealed that counting only the three acoustic modes and neglecting the low-frequency optical modes lead to significant underestimation of the ITC using DMM. Our findings indicate that it is imperative to use the exact full phonon dispersion relations in evaluating the ITC for low-dimensional layered materials.

We point out that the effective channel for the interfacial thermal conductance, the inverse of Kapitza resistance, of metal-insulator/semiconductor interfaces is governed by the electron-phonon interaction mediated by the surface states allowed in a thin region near the interface. Our detailed calculations demonstrate that the interfacial thermal conductance across Pb/Pt/Al/Au-diamond interfaces are only slightly different among these metals, and reproduce well the experimental results of the interfacial thermal conductance across metal-diamond interfaces observed by Stoner et al. [Phys. Rev. Lett. 68, 1563 (1992)] and most recently by Hohensee et al. [Nature Commun. 6, 6578 (2015)]., Comment: 15 pages, 4 figures

Interfacial thermal conductance between dissimilar materials plays an important role in solving the overheating problem and thus improving the performance of photonic and electronic devices, especially those at micro- and nano-scale. However, conclusive heat transfer mechanism across interfaces is absent, especially across metal–nonmetal interfaces. Heat transfer across a metal–nonmetal interface is determined by the interplay among different heat carriers. In the metal, both electrons and phonons carry heat, while in the nonmetal, only the phonons are the dominant heat carriers. The interactions among these carriers can be classified into three categories, which correspond to three heat transfer channels, i.e. (i) phonon(metal)–phonon(nonmetal) interactions, which have been widely studied on the basis of the acoustic mismatch theory, diffuse mismatch model, lattice/molecular dynamics simulations; (ii) electron(metal)–phonon(metal) interactions followed by phonon(metal)–phonon(nonmetal) interactions, which were introduced to provide thermal resistance in series with that of the first channel; (iii) electron(metal)–phonon(nonmetal) direct interactions. The third channel has been introduced in order to explain the deviation between experimental results and the existing models incorporating the channel (i) and the channel (ii). Currently, there have been no models to comprehensively capture the underlying mechanism, mainly due to the difficulty in determining/defining the interfacial states at microscopic level and the temperature. Experimentally, it is hard to distinguish the contributions from these channels due to the resolution/sensitivity of the experimental system. Therefore, we here mainly concern with the investigations on the contributions of the channel (iii) from both experimental and theoretical aspects.

Recent research has highlighted the potential to achieve high-thermal-conductivity polymers by aligning their molecular chains. Combined with other merits, such as low-cost, corrosion resistance, and light weight, such polymers are attractive for heat transfer applications. Due to their quasi-one-dimensional structural nature, the understanding on the thermal transport in those ultra-drawn semicrystalline polymer fibers or films is still lacking. In this paper, we built the ideal repeating units of semicrystalline polyethylene and studied their dependence of thermal conductivity on different crystallinity and interlamellar topology using the molecular dynamics simulations. We found that the conventional models, such as the Choy-Young's model, the series model, and Takayanagi's model, cannot accurately predict the thermal conductivity of the quasi-one-dimensional semicrystalline polyethylene. A modified Takayanagi's model was proposed to explain the dependence of thermal conductivity on the bridge number a...

In this paper, spectrum sensing is investigated when the decision statistic is computed using energy detection (ED) with Welch’s method in the frequency domain. First, we assume an estimated noise variance is used to calculate the threshold, instead of the priori exact noise. We present an analytical model to evaluate the performance of the conventional Welch’s ED. The characteristics of this model are also analyzed to show the effect for the performance of spectrum sensing. Then an optimal threshold is proposed to achieve high detection probability and low false alarm probability at low SNR levels. The analytical results and simulations demonstrate the effectiveness of the proposed optimal threshold.

We propose a type of thermoelectric materials incorporating metallic nanowires in insulating polymers. It is shown that the hybridization of poor thermoelectric materials such as metal and polymer can achieve high performance of thermoelectricity. The electrical conductivity of such hybrid materials is controllable by the volume fraction of metallic nanowires which is above a percolation critical value. Meanwhile, the Seebeck coefficient shows a weak dependence on the volume fraction. Low thermal conductivities required for achieving the high figure of merit can be fulfilled from both the low thermal conductivity of polymer and the interfacial thermal resistance between nanowires and polymer. In this regard, we propose the concept “electron-percolation thermal-insulator,” providing a guide to design efficient hybrid thermoelectric materials.

The substitution of Cu+ in Cu3SbS4 nano crystals by magnetic Ni2+ increases electrical conductivity while nearly retaining the Seebeck coefficient, due to the spin effect. This demonstrates that the substitution of Cu+ by Ni2+ can notably improve the thermoelectric performance of a ternary Cu3SbS4 system.

This paper considers compressive sensing (CS) reconstruction with magnitude prior information. The magnitude prior information is described by mean and covariance of the unknown signal. Towards a reconstruction with minimum mean square errors (MMSE), we propose several CS reconstruction algorithms that use the magnitude prior information. Numerical simulations demonstrate that our approach reduces the reconstruction distortion. Potential applications of the proposed techniques include radio spectrum surveillance, sensor networks, etc. (5 pages)

We theoretically investigate the enhancement of thermoelectric cooling performance in thermoelectric devices made of materials with inhomogeneous thermal conductivity, beyond the usual practice of enhancing thermoelectric figure of merit ZT. The dissipation of Joule heat in such thermoelectric devices is asymmetric which can give rise to better thermoelectric cooling performance. Although the thermoelectric figure of merit and the coefficient-of-performance are only slightly enhanced, both the maximum cooling power and the maximum cooling temperature difference can be enhanced significantly. This finding can be used to increase the heat absorption at the cold end. The asymmetric dissipation of Joule heat also leads to thermal rectification., Comment: 20 pages and 3 figures