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In this study, a nitrogen-doped multi-walled carbon nanotube (N-MWCNTs)/silver nanowire (AgNWs) nanocomposite electrode was prepared, using polydimethylsiloxane (PDMS) as a flexible substrate and N-MWCNTs and AgNWs as conductive materials. Trace Cu(II) in water was monitored by square wave stripping voltammetry (SWSV). Compared with commercial electrodes, the N-MWCNTs/AgNWs composite electrode generated much higher responsive peak current in detecting Cu(II), due to the enhanced conductivity of the composite electrode and the strong complexing ability of the N-MWCNTs for Cu(II). In the SWSV, this new electrode showed 0.06 μg/L (S/N = 3) limit of detection, a linear range from 0.500 to 100 μg/L, high resistance to interfering metals such as Ca(II), K(I), Zn(II), Na(I), Al(III), Fe(III), Hg(II), Cr(VI), Bi(III), Sb(III) and Sn(II), and stable response in natural water samples without sample pretreatment. This study established a new method for facile fabrication of high-performance flexible Cu(II) sensor with N-MWCNTs and AgNWs.

We developed a highly selective and efficient multicomponent transformation by utilizing alkynes and olefins/(hetero)arenes through photoinduced energy-transfer catalysis. The reaction involves the formation of three distinct chemical bonds, namely C(sp3)–C(sp2), C(sp2)–C(sp3), and C(sp3)–N, in a single coordinated manner. The strategy used a vinyl radical-mediated radical relay approach under mild conditions, exhibiting a broad substrate scope (>70 examples), excellent functional-group tolerance, and remarkable regio- and anti-stereoselectivity. Through the utilization of a combination of experimental techniques and density functional theory (DFT), we delved deeper into the mechanistic intricacies of this distinctive system. Results revealed that the selective radical addition to electron-deficient alkynes, rather than olefins, was governed by the inherent reactivity of alkyl radicals. This discovery presented a highly effective approach for the synthesis of stereodefined multisubstituted alkenes.

High-temperature ionothermal synthesis has been proven effective in preparing environment-friendly carbon nitride (CN)-based photocatalysts in either triazine or heptazine form for CO2reduction reaction (CO2RR). However, such a process is usually energy-intensive and suffers from partial carbonization that results in non-porous catalysts and degenerating their activities. Herein, we report the preparation of highly porous CN polymers (porous C6N7, C3N3, C4.5N5) through a low-temperature solvothermal polymerization of cyameluric chloride itself or cyanuric chloride itself, or both, respectively. As such, it avoids unfavorable carbonization and allows for fine control of its chemical structure and significantly enlarged surface area (up to 669 m2g−1). The pincer-like 2,2′-bipyridine sites of porous C6N7alter the photocatalytic CO2reduction pathways via stabilizing the *HCO intermediates, which promotes further hydrogenation to produce CH4in a high selectivity. Benefiting from the carbonization-free polymerization, high porosity, and *HCO intermediate activation, porous C6N7gave a superior CO2RR to CH4performance (17.18 µmol g−1h−1) as well as high stability (5 successive cycles), outperforming the bulk and state-of-the-art counterparts of CN. This opens an avenue for the rational construction of efficient porous CN-based photocatalytic systems, demonstrating their great potential in energy conversion reactions.

The near-infrared (NIR) method has shown great potential in estimating key parameters in various industrial processes. Selecting characteristic wavelengths from high-dimensional spectra is crucial in building a prediction model with the satisfactory performance. However, existing wavelength selection methods based on the wavelength or waveband importance estimation are time-consuming and unstable. To improve the stability and generalization of the established model, a novel adaptive robust method is proposed for NIR modeling in this work, in which the pattern-coupled sparse model has been developed to estimate the spectral peak wavebands adaptively. Furthermore, a robust method based on global-local shrinkage is developed for characteristic wavelength selection. Compared with the state-of-the-art techniques, the proposed method is more accurate and robust for NIR modeling on both benchmark and real datasets.

• The cobalt-free Mn-LLOs cathode materials with a small amount of Li 2 MnO 3 crystal domain in the bulk structure and gradient doping of Al and Ti elements have been developed. • The batteries with Mn-LLOs cathode deliver the energy density over 600 Wh kg−1, excellent cycle retention of 99.7 % after 800 cycles with low voltage decay of 0.03 mV cycle−1. • The Mn-LLOs cathode materials with bulk structure design and interface regulation can improve the long-time cycling stability of low-cost Mn-based energy storage batteries. The cobalt-free Mn-based Li-rich layered oxide material has the advantages of low cost, high energy density, and good performance at low temperatures, and is the promising choice for energy storage batteries. However, the long-cycling stability of batteries needs to be improved. Herein, the Mn-based Li-rich cathode materials with small amounts of Li 2 MnO 3 crystal domains and gradient doping of Al and Ti elements from the surface to the bulk have been developed to improve the structure and interface stability. Then the batteries with a high energy density of 600 Wh kg−1, excellent capacity retention of 99.7 % with low voltage decay of 0.03 mV cycle−1 after 800 cycles, and good rates performances can be achieved. Therefore, the structure and cycling stability of low voltage Mn-based Li-rich cathode materials can be significantly improved by the bulk structure design and interface regulation, and this work has paved the way for developing low-cost and high-energy Mn-based energy storage batteries with long lifetime. [Display omitted] [ABSTRACT FROM AUTHOR]

Chiral boronic esters are a class of versatile building blocks. We describe herein an asymmetric nickel-catalyzed borylative coupling of terminal alkenes with nonactivated alkyl halides. The success of this asymmetric reaction is ascribed to the application of a chiral anionic bisoxazoline ligand. This study provides a three-component strategy to access α- and β-stereogenic boronic esters from easily accessible starting materials. This protocol is characterized by mild reaction conditions, wide substrate scope and high regio- and enantioselectivity. We also showcase the value of this method in simplifying the synthesis of several drug molecules. Mechanistic studies suggest that the generation of enantioenriched boronic esters bearing an α-stereogenic center results from a stereoconvergent process, while the enantioselectivity-controlling step in the generation of boronic esters with a β-stereocenter is switched to the olefin migratory insertion step due to coordination of an ester group.

Spatial patterns of plant species and patchy community are important properties in grasslands. However, research regarding spatial patterns of formed patches with various species has not fully advanced until now. Our purpose is to clarify differences in spatial pattern formed by species and community constructed under shady and terrace habitats. The three common Kobresia-Carexpatches (Size 1, 0.6–0.9 m2; Size 2, 3.0–3.8 m2and Size 3, 6.5–8.8 m2) were selected in shady and terrace on the Qinghai-Tibetan Plateau, and corresponding quadrats of 1m×1m, 2m×2m and 3m×3m were placed for S1, S2 and S3 patches, respectively. The surveyed quadrats were divided into 20cm×20cm large cells (L-cells), and further divided into four 10cm×10cm small cells (S-cells). We used the binary occurrence system (presence/absence data) to record occurrences of all species in S-cells. The analysis shows that the power law model was well able to determine the spatial distribution pattern of species or patchy community in shady and terrace. All species and patches show aggregated distribution in shady and terrace habitats. In the shady habitat, the relative spatial heterogeneity (ε) of individual plant species was lowest at presence frequency (P) of 0.1–0.3, whereas in the terrace habitat εwas lowest at P <0.1, and ε increased monotonically with increasing P. For most dominant species, Pand εvalues were higher in terrace than those in shady. We concluded that the dominant species largely determine spatial heterogeneity of the Kobresia-Carexpatches, while companion and rare species have weak influence on the community-level heterogeneity in shady and terrace habitats.

Near-infrared (NIR) spectroscopy has become an important analytical tool to perform rapid characterization of petroleum products due to its effectiveness and efficiency. However, NIR analysis is a typical small sample problem, and a unitary regression model under specific assumption often suffers from poor generalization ability during online implementation. Besides, the interpretability of complex machine learning models is relative incompetent to reveal the variable contribution of wavelength variables, which is significant to guarantee the model reliability in practical application. Thus, this article proposes a novel ensemble learning algorithm to improve the poor model generalization ability caused by insufficient sample size and complex unexpected online application situations. Furthermore, the constructed model is interpreted by combining model-agnostic explanation method with spectral structure knowledge, and a novel reliability index (RI) is proposed to ensure model reliability in practice. The prediction performance of the proposed algorithm is verified using two industrial NIR datasets. Experimental results confirm the effectiveness of the proposed ensemble learning algorithm. The model interpretability and model reliability are guaranteed by the proposed interpretation method.

Background:Acute lung injury (ALI) induced by sepsis is distinguished by an inflammatory progression. Herein, we investigated the action of circular RNA kelch like family member 2 (circKlhl2) in sepsis-induced ALI. Methods:The animal or cell model of sepsis ALI was established by LPS stimulation. The contents of circKlhl2, microRNA-29b-3p (miR-29b-3p), rho-associated coiled-coil containing protein kinase 1 (ROCK1), CyclinD1, B-cell lymphoma-2 (Bcl-2), and cleaved-caspase 3 (C-caspase-3) were detected by quantitative real-time polymerase chain reaction and western blot, respectively. Cell viability was assessed by cell counting kit 8 assay. Cell cycle and apoptosis were evaluated by flow cytometry. The abundances of proinflammatory cytokines were detected by enzyme-linked immunosorbent assay. Besides, the targeted relationship between miR-29b-3p and circKlhl2 or ROCK1 was verified by dual-luciferase reporter assay, RNA immunoprecipitation assay and RNA pull-down assay. Results:Loss of circKlhl2 mitigated lung injury and proinflammatory cytokine expression in sepsis-ALI mice model and alleviated LPS-induced apoptosis and inflammatory response in microvascular endothelial cell (MPVECs) in vitro. The abundances of circKlhl2 and ROCK1 were boosted, while the miR-29b-3p level was diminished in the animal or cell model of sepsis-ALI. MiR-29b-3p inhibition abrogated circKlhl2 knockdown-mediated effects on MPVECs injury. Moreover, miR-29b-3p overexpression promoted cell proliferation and inhibited apoptosis and inflammation in LPS-treated MPVECs, while ROCK1 enhancement reversed these effects. Conclusion:CircKlhl2 expedited the sepsis-induced ALI by adjusting miR-29b-3p/ROCK1 axis.

In near-infrared (NIR) modeling, the baseline drift tends to affect the qualitative and quantitative performance of the multivariate calibration model. The baseline correction method based on the sparse representation of independent wavelength is a recent method for pure spectra estimation. In fact, the measured NIR generally exhibit local wavelength coupling sparse properties, and the existing baseline correction methods suffer from performance degradation due to ignoring the wavelength coupling effect on baseline correction. In this article, the pattern-coupled learning framework considering the local coupling property is proposed to achieve pure spectrum fitting and baseline correction simultaneously. Specifically, the pattern-coupled hierarchical Gaussian prior model is introduced to characterize the local sparse structure corresponding to characteristic peaks with wavelength coupling. The adaptive coupling method is further proposed to achieve robust learning of NIR under different noise interference. Unlike conventional frameworks where wavelength or hyperparameters are learned independently, the proposed mode coupling framework enables accurate baseline estimation without prior knowledge of spectral structure by characterizing wavelength coupling properties. Compared with the state-of-the-art methods, the root mean square error (RMSE) and $R^{2}$ of the proposed method are reduced and increased by 14.41% and 1.53%, 14.12% and 2.01%, 12.86% and 12.93% in three measured NIR datasets, respectively.

Traditional cross-couplings catalyzed by transition metal catalysts generally rely on the classic oxidative addition–transmetalation–reductive elimination process, which requires low-valent precious metals and an inert atmosphere and which initiates from carbon–alide or pesudo carbon–halide bonds. Herein, an unprecedented molybdenum–oxo-complex-catalyzed intermolecular cross-coupling of benzyl alcohols has been reported. Various alcohols including primary, secondary, and tertiary substrates can proceed efficiently under these conditions. Several functional groups sensitive to the low-valent transition metals, such as aryl halides, can be well tolerated. The mechanistic studies and DFT calculations suggest that an intramolecular concerted cyclization was involved in the reverse [2 + 2]-type elimination process.

An urgent demand for electronic and optoelectronic devices able to work in extreme environments promotes a series of research studies on semiconductor materials. Cubic boron phosphide (BP) as a semiconductor material with excellent characteristics shows great application potential. However, since the synthesis conditions required are difficult to achieve and the growth mechanism of BP is still unclear, there are few reports on the basic properties of BP and pure isotope BP, resulting in a narrow understanding of their special physical properties. Here, we successfully obtained highly pure isotopic 10BP crystals by a vapor–liquid–solid (VLS) method unconventionally designed, which successfully overcomes the thermodynamic conflict between the high melting point of the boron element and low sublimation temperature of the phosphorus element. The 10BP achieved owns an aspect ratio as high as 104and a hardness up to 41 GPa. Besides, as an indirect bandgap semiconductor, it has ultrawide red emission spectra, a p-type conductivity with extremely low resistivity, and excellent photoelectronic and piezoelectric characteristics. Furthermore, compared with other superhard semiconductors like cubic BN and diamond, 10BP has an obvious advantage of lower growth temperature (1200 °C). All these characteristics confirm the prospects owned by 10BP in its applications to the field of high-conductivity, optoelectronic, strain-sensing, and superhard semiconductors.

One judiciously designed strategy of utilizing an ultrathin but conductive Ga2O3:Si nanolayer to prepare (AlGa)2O3crystalline film is demonstrated. Benefiting from the existence of Ga2O3:Si nanolayer, a high-quality (Al0.68Ga0.32)2O3sesquioxide film with 68 at.% aluminum was epitaxially grown on sapphire substrates, which was characterized by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. Its bandgap was broadened to 6.14 eV, and a vacuum ultraviolet (VUV) (AlGa)2O3/Ga2O3:Si photodetector was subsequently fabricated. The detector exhibits a pretty high on-off ratio of about 103, an open-circuit voltage of 1.0 V and a responsivity of 8.1 mAW−1at 0 V bias voltage. The performances imply that the proposed strategy is valuable for improving the quality and also adjusting the bandgap of (AlGa)2O3sesquioxides, which is expected to facilitate their application in VUV photodetection.

To accurately predict the combustion and emissions characteristics of a diesel engine fueled with n-butanol/diesel blends, a more realistic compact-sized skeletal mechanism with (149 species and 497 reactions) was developed in this study based on the decoupling method. It was generated by integrating the simplified fuel-related sub-mechanisms of n-butanol and diesel surrogates including n-dodecane, iso-cetane, iso-octane, toluene, and decalin. The same detailed core sub-mechanisms of C2-C3and H2/CO/C1, in which the formation and oxidation of benzene (A1) and larger polycyclic aromatic hydrocarbon (PAH) up to coronene (A7) of alkanes, aromatics, cycloalkanes and alcohols were used. The PAH formation behavior of individual fuel components in the mechanism were analyzed in detail based on the methods of pathway analysis, rate of production and sensitivity analysis. The mechanism was extensively validated against ignition delay time, laminar flame speed, species profile and three-dimensional engine simulation. The results show that the effects of fuel types on the PAH formation are satisfactorily captured, and the combustion characteristics of n-butanol/diesel blends and each component are reliably reproduced by the current mechanism.

Near-infrared spectroscopy (NIRS) is an outstanding detection technology with fast, nondestructive, on-line characteristics, which has been used in many fields to achieve qualitative/quantitative detection of products. This study proposes an analysis method that combines a one-dimensional convolution neural network (1-CNN) with NIRS to select a characteristic wavelength for a subsequent qualitative/quantitative analysis, while considering fully dimensional NIRS information. Batch normalization (BN) and an exponential decay learning rate are embedded into the training stage of the 1-CNN which improves performance and reduces the risk of overfitting. The proposed method is used for NIRS of dried matsutake samples from four regions in China, and a geographical origin identification model is established for the matsutake. The developed 1-CNN model achieves better classification accuracy than traditional models. The experimental results demonstrate that the proposed 1-CNN achieves good generalization and can act as an alternative method for analyzing NIRS data.

In order to establish nomograms that could forecast the postoperative survival for patients with appendiceal cancer after surgery, this study collected 5945 patients with surgically removed appendiceal cancer from the Surveillance, Epidemiology, and End Results database. Overall survival (OS) and cancer-specific survival (CSS) were analyzed by Cox regression analysis and nomograms. The population was randomly separated into a training group (n= 3963) and a validation group (n= 1982). Age, histological grade, T stage, N stage, regional nodes examination, tumor size, and CEA were independent prognostic factors for OS and were used in the nomogram. In addition, radiotherapy and chemotherapy were independent prognostic factors for CSS. The C-index values of the nomograms predicting postoperative OS and CSS were 0.76 (95% CI 0.74–0.78) and 0.80 (95% CI 0.78–0.82) in the training group and 0.77 (95% CI 0.74–0.79) and 0.81 (95% CI 0.78–0.84) in the validation group. Moreover, nomograms were better than traditional American Joint Committee on Cancer (AJCC) TNM 8th Edition Staging System in predicting prognosis derived from the results of DCA and ROC curves. In a word, we constructed new nomograms based on a large database that can accurately predict the OS and CSS of patients with appendiceal cancer after surgery.

Tricholoma matsutakeis an expensive product in the global edible fungus market due to its nutritional and medicinal properties. As the price of T. matsutakeincreases, some adulterated and fraudulent products have also emerged in the market. It is difficult to detect the fraudulent products with similar shape, and the unfair competition often happens. Discriminant methods combined near infrared spectroscopy with chemometrics analysis have been used in many fields. However, due to the high correlation between the spectral data, it is difficult to construct an effective model using original spectra. In this work, a discriminated model developed by the elastic net algorithm and near infrared spectroscopy is presented to determinate the adulterated and fraudulent products of T. matsutake. First, the difference of protein and aspartic acid contents between T. matsutakeand three products with similar shape were analyzed. Then, the information variables selected from near infrared spectroscopy using the elastic net were used to establish quantitative models. And, the prediction performance of developed models was evaluated by using the validation set. Finally, the Monte Carlo experiment based on the test set demonstrated the effectiveness of the proposed method. Compared with least absolute shrinkage and selection operator and partial least square regression models, the developed model has a great prediction accuracy and robustness, which can be served as a new discriminant method for T. matsutakeadulteration determination.

Tricholoma matsutake is an expensive product in the global edible fungus market due to its nutritional and medicinal properties. As the price of T. matsutake increases, some adulterated and fraudulent products have also emerged in the market. It is difficult to detect the fraudulent products with similar shape, and the unfair competition often happens. Discriminant methods combined near infrared spectroscopy with chemometrics analysis have been used in many fields. However, due to the high correlation between the spectral data, it is difficult to construct an effective model using original spectra. In this work, a discriminated model developed by the elastic net algorithm and near infrared spectroscopy is presented to determinate the adulterated and fraudulent products of T. matsutake. First, the difference of protein and aspartic acid contents between T. matsutake and three products with similar shape were analyzed. Then, the information variables selected from near infrared spectroscopy using the elastic net were used to establish quantitative models. And, the prediction performance of developed models was evaluated by using the validation set. Finally, the Monte Carlo experiment based on the test set demonstrated the effectiveness of the proposed method. Compared with least absolute shrinkage and selection operator and partial least square regression models, the developed model has a great prediction accuracy and robustness, which can be served as a new discriminant method for T. matsutake adulteration determination.

Recently, much attention has been paid to the direct use of acetone–n-butanol–ethanol (ABE) as a biofuel. However, the skeletal mechanism of ABE for engine applications was rarely reported. Therefore, a skeletal mechanism to predict the combustion and emission characteristics of diesel–ABE blends in engines was developed in this study. A reduced mechanism considering the oxidation of acetone, n-butanol, and ethanol was first established on the basis of the methods of directed relation graph with error propagation and sensitivity analysis, computational singular perturbation, and reaction pathway analysis. It was then combined with a reduced n-heptane/toluene mechanism with soot formation mechanism embedded and a reduced NOxformation mechanism. After optimizing the reaction rate constants of the key reactions in the coupled mechanism, the skeletal mechanism of n-heptane/toluene–acetone–n-butanol–ethanol (referred as HT-ABE) consisting of 127 species and 507 reactions was finally generated and validated against ignition delay times, premixed flame species profiles, and three-dimensional (3D) engine simulations. The results show that the combustion and emission characteristics of diesel–ABE blends are well reproduced by the current mechanism. It is indicated that the newly developed HT-ABE mechanism can be applied to simulate practical ABE combustion in a diesel engine.

The hot extrusion process of an Al-Zn-Mg plate was studied via numerical and experimental methods. The multi-objective optimization method was employed to optimize the structure of the feeder chamber. Additionally, an extrusion experiment was conducted using the optimal feeder chamber. Based on above analysis, the optimal structure of the feeder chamber was obtained, and the standard deviation of the flow velocity was decreased from 0.827 to 0.499mm/s. Meanwhile, the die displacement and extrusion load were also reduced significantly. The extruded plate consisted of substructures, elongated grains, and fine grains of several microns, which was evidence of the dynamic recovery and partial dynamic recrystallization. The main textures of the extruded plate were deformed Brass, S, and Copper, as well as some recrystallized Cube. However, the fraction of the aforementioned texture components exhibited significant variation in the center and edge areas of the extruded plate. The center of the plate exhibited higher hardness, lower elongation, and lower ultimate tensile strength than the edge area. Differences in the tensile properties along 0°, 45°, and 90° were observed, indicating the anisotropy of the extruded Al-Zn-Mg plate.

ABSTRACTAn approach was developed to calculate the crack susceptibility under various levels of pressure, and the corresponding numerical method was presented. The binary Al–Si alloy system was selected for study because the effect of high pressure on its phase diagram has been reported. The results showed a higher pressure can lead to a higher crack susceptibility and shift the most crack susceptible composition to higher solute contents. It was found a higher pressure can increase the effect of back diffusion on the solidification path and hence the crack susceptibility. This study provides a new understanding of the effect of pressure on solidification cracking susceptibility and can be a relevant starting point for studying solidification cracking under high pressures.

In this study, maleic anhydride-modified lignin (LG-M), a ROS-cleavable thioketal (TK) bond, and polyethylene glycol (PEG) were used to synthesize a lignin-based copolymer (LG-M(TK)-PEG). Doxorubicin (DOX) was attached to the ROS-cleavable bond in the LG-M(TK)-PEG for the preparation of the ROS-activatable DOX prodrug (LG-M(TK-DOX)-PEG). Nanoparticles (NPs) with a size of 125.7 ± 3.1 nm were prepared by using LG-M(TK-DOX)-PEG, and they exhibited enhanced uptake by cancer cells compared to free DOX. Notably, the presence of lignin in the nanoparticles could boost ROS production in breast cancer 4T1 cells while showing little effect on L929 normal cells. This selective effect facilitated the specific activation of the DOX prodrug in the tumor microenvironment, resulting in the superior tumor inhibitory effects and enhanced biosafety relative to free DOX. This work demonstrates the potential of the LG-M(TK-DOX)-PEG NPs as an efficient drug delivery system for cancer treatment.

Abstract

Graphene (Gr) has been widely used as a transparent electrode material for photodetectors because of its high conductivity and high transmittance in recent years. However, the current low-efficiency manipulation of Gr has hindered the arraying and practical use of such detectors. We invented a multistep method of accurately tailoring graphene into interdigital electrodes for fabricating a sensitive, stable deep-ultraviolet photodetector based on Zn-doped Ga2O3films. The fabricated photodetector exhibits a series of excellent performance, including extremely low dark current (∼10–11A), an ultrahigh photo-to-dark ratio (>105), satisfactory responsivity (1.05 A/W), and excellent selectivity for the deep-ultraviolet band, compared to those with ordinary metal electrodes. The raise of photocurrent and responsivity is attributed to the increase of incident photons through Gr and separated carriers caused by the built-in electric field formed at the interface of Gr and Ga2O3:Zn films. The proposed ideas and methods of tailoring Gr can not only improve the performance of devices but more importantly contribute to the practical development of graphene.

Spot welding has been a remarkably important joint method for automotive body engineering. Based on a simplified two-dimensional analytical model in a lap-shear specimen, the elastic analytical solutions near spot weld nugget are theoretically derived to analyze stress distributions. A Cartesian coordinate system is centered at the center of the nugget, and the shear or resultant force acting on the nugget is marked as the positive x-direction. The results show that the normalized radial and hoop stresses are negative at the angle intervals between [66.25°, 113.75°] and [246.25°, 293.74°], while the normalized shear stress is negative at the angle intervals between [0°, 90°] and [180°, 270°]. It can be observed that the locations with the initial yielding failure change gradually from the normalized radial distance of 1.34 to the circumference of the spot weld nugget, and finally to the infinity as the angle increases. The normalized effective stress could approach to 1.84 as the normalized radial distance goes to infinity. In addition, the obtained analytical solutions are validated in the comparison with numerical results. The locations with peak Von Mises stresses along the circumference of the spot weld nugget have a good agreement with the analytical solutions. It indicates that the initial yielding locations would likely occur at the four special angles of the spot weld nugget. Therefore, the derived stress distributions in this study are beneficial for analyzing yielding failure behavior or evaluating damage evolution on engineering structures jointed with spot welds.

Vacuum-ultraviolet (VUV) detector equipped on satellites has extensive application in space exploration and cosmic science. For a VUV detector, a semiconductor material with a sufficiently wide band gap is eagerly desired. In this work, a wide-band gap amorphous-MgGaO (a-MGO) film was epitaxially grown on n-type GaN substrate by atomic layer deposition and a p–i–n-type heterojunction device for VUV detection was constructed with a-MGO film as a photosensitive layer and p-type graphene as a transparent conductive layer. The device exhibits a good spectral selectivity of VUV with photovoltaic response, a high responsivity (2 mA W–1) under zero bias, and an ultrafast response speed (rise and decay time of 0.76 μs and 0.56 ms, respectively) under nanosecond VUV pulse irradiation. This newly developed device shows great potential in VUV detection for space exploration.

The superconducting nanowire single-photon detector (SNSPD) is used to detect the sunlight reflected by the artificial satellite and space debris. In the process, light curves of the satellite and space debris are successfully measured. In 2017, a space-debris laser ranging system with a four-element SNSPD is developed by Yunnan Observatories in China. During the ranging experiments, the detector works in a freely detecting state. It can detect photons not only of the laser echo, but also of the sunlight reflected by the target. After separating the data triggered by background light from the whole detected data set, the light curves of satellites, including Topex and several types of debris, are acquired. The apparent rotation rate of the satellite Topex is determined by analyzing the light curves by Fourier transform and phase dispersion minimization. On the basis of a laser ranging system using SNSPDs, the simultaneous measurement of the laser ranging and light curves of some space targets without any additional equipment is realized for the first time, to the best of our knowledge.

A kind of L 2 -convergence theorems for the state dependent branching processes with continuous state and discrete time is studied and a group of sufficient conditions is obtained. [ABSTRACT FROM AUTHOR]

Afforestation is conducive to soil carbon (C) sequestration in semi-arid regions. However, little is known about the effects of afforestation on sequestrations of total and labile soil organic carbon (SOC) fractions in semi-arid sandy lands. In the present study, we examined the effects of Caragana microphyllaLam. plantations with different ages (12- and 25-year-old) on sequestrations of total SOC as well as labile SOC fractions such as light fraction organic carbon (LFOC) and microbial biomass carbon (MBC). The analyzed samples were taken from soil depths of 0–5 and 5–15 cm under two shrub-related scenarios: under shrubs and between shrubs with moving sand dunes as control sites in the Horqin Sandy Land of northern China. The results showed that the concentrations and storages of total SOC at soil depths of 0–5 and 5–15 cm were higher in 12- and 25-year-old C. microphyllaplantations than in moving sand dunes (i.e., control sites), with the highest value observed under shrubs in 25-year-old C. microphyllaplantations. Furthermore, the concentrations and storages of LFOC and MBC showed similar patterns with those of total SOC at the same soil depth. The 12-year-old C. microphyllaplantations had higher percentages of LFOC concentration to SOC concentration and MBC concentration to SOC concentration than the 25-year-old C. microphyllaplantations and moving sand dunes at both soil depths. A significant positive correlation existed among SOC, LFOC, and MBC, implying that restoring the total and labile SOC fractions is possible by afforestation with C. microphyllashrubs in the Horqin Sandy Land. At soil depth of 0–15 cm, the accumulation rate of total SOC under shrubs was higher in young C. microphyllaplantations (18.53 g C/(m2•a); 0–12 years) than in old C. microphyllaplantations (16.24 g C/(m2•a); 12–25 years), and the accumulation rates of LFOC and MBC under shrubs and between shrubs were also higher in young C. microphyllaplantations than in old C. microphyllaplantations. It can be concluded that the establishment of C. microphyllain the Horqin Sandy Land may be a good mitigation strategy for SOC sequestration in the surface soils.

The machine learning/statistics literature has so far considered largely multi-armed bandit (MAB) problems in which the rewards from every arm are assumed independent and identically distributed. For more general MAB models in which every arm evolves according to a rewarded Markov process, it is well known the optimal policy is to pull an arm with the highest Gittins index. When the underlying distributions are unknown, an empirical Gittins index rule with ε -exploration (abbreviated as empirical ε -Gittinx index rule) is proposed to solve such MAB problems. This procedure is constructed by combining the idea of ε -exploration (for exploration) and empirical Gittins indices (for exploitation) computed by applying the Largest-Remaining-Index algorithm to the estimated underlying distribution. The convergence of empirical Gittins indices to the true Gittins indices and expected discounted total rewards of the empirical ε -Gittinx index rule to those of the oracle Gittins index rule is provided. A numerical simulation study is demonstrated to show the behavior of the proposed policies, and its performance over the ε -mean reward is discussed. [ABSTRACT FROM AUTHOR]

Chain-walking has emerged as a promising strategy in organic synthetic methodology, but achieving site-selectivity in reactions involving competition among multiple potential positions remains a challenge. In this study, we presented a novel approach to ligand-modulated, nickel-catalyzed regiodivergent alkenylboration of allylarenes. Our method allows for highly chemoselective preparation of two classes of structurally different alkenyl boronates from the same starting by simply switching the ligand. Mechanistic investigations involving experiments and calculations suggest that the ligand-modulating regiodivergence arises from either regioselective β-H elimination or oxidative addition with organic halides. Our findings offer valuable insight into addressing site-selective issues in chain-walking reactions with multiple thermodynamically stable factors.

This study simulated the composite regeneration process of a Catalyzed Diesel Particulate Filter (CDPF). The degradation performance was evaluated using the maximum wall temperature as the benchmark. The orthogonal experiment design and fuzzy grey correlation analysis approach were employed to analyze the effect of various factors, including regeneration temperature, NOx mass, catalyst coating amount, SO2 concentration, oxygen concentration, and exhaust flow rate, on the degradation of the CDPF. A comprehensive analysis of the factors was conducted, yielding important insights into the key factors that can be leveraged to optimize the system. The results reveal that these six operating parameters are the primary drivers of the CDPF’s performance degradation, with the NOx mass having the greatest impact on the maximum wall temperature.

Satellite laser ranging operating at 1064 nm wavelength using superconducting nanowire single-photon detectors (SNSPDs) is successfully demonstrated. A SNSPD with an intrinsic quantum efficiency of 80% and a dark count rate of 100 cps at 1064 nm wavelength is developed and introduced to Yunnan Observatory in China. With improved closed-loop telescope systems (field of view of about 26^′′), satellites including Cryosat, Ajisai, and Glonass with ranges of 1600 km, 3100 km, and 19,500 km, respectively, are experimentally ranged with mean echo rates of 1200/min, 4200/min, and 320/min, respectively. To the best of our knowledge, this is the first demonstration of laser ranging for satellites using SNSPDs at 1064 nm wavelength. Theoretical analysis of the detection efficiency and the mean echo rate for typical satellites indicate that it is possible for a SNSPD to range satellites from low Earth orbit to geostationary Earth orbit.

China’s Horqin Sandy Land, a formerly lush grassland, has experienced extensive desertification that caused considerable carbon (C) losses from the plant-soil system. Natural restoration through grazing exclusion is a widely suggested option to sequester C and to restore degraded land. In a desertified grassland, we investigated the C accumulation in the total and light fractions of the soil organic matter from 2005 to 2013 during natural restoration. To a depth of 20 cm, the light fraction organic carbon (LFOC) storage increased by 221 g C/m2(84%) and the total soil organic carbon (SOC) storage increased by 435 g C/m2(55%). The light fraction dry matter content represented a small proportion of the total soil mass (ranging from 0.74% in 2005 to 1.39% in 2013), but the proportion of total SOC storage accounted for by LFOC was remarkable (ranging from 33% to 40%). The C sequestration averaged 28 g C/(m2·a) for LFOC and 54 g C/(m2·a) for total SOC. The total SOC was strongly and significantly positively linearly related to the light fraction dry matter content and the proportions of fine sand and silt+clay. The light fraction organic matter played a major role in total SOC sequestration. Our results suggest that grazing exclusion can restore desertified grassland and has a high potential for sequestering SOC in the semiarid Horqin Sandy Land.

Extending the studies on the preparation of nanoparticles using green chemistry, we present here a facile and simple method for the fabrication of copper oxide (CuO) nanoparticles using Tragopogon collinusleaf extract. The characteristics of biologically synthesized CuO nanoparticles were determined by several techniques including UV–vis spectroscopy, FITR, XRD, XPS, TEM, and DLS. Subsequently, the anticancer activity of bio-fabricated CuO nanoparticles against human leukemia (K562) cell line was assessed through MTT, ROS, apoptosis, caspase-9/-3, mitochondrial membrane potential (MMP), and qPCR analyses, whereas lymphocytes were used as control. The outcomes demonstrated that crystalline CuO nanoparticles had an average size of 50 nm, a zeta potential of - 33.91 mV, and a hydrodynamic radius of 88.31 nm with a PDI of 0.193, revealing the high dispersion ability of the nanoparticles. The cytotoxic activity against K562 cell line and lymphocytes showed that fabricated CuO nanoparticles had a selective anticancer activity against K562 cells through generation of ROS, apoptosis induction, elevation of caspase-9/-3 activity, reduction of MMP, overexpression of Bax and caspase-9/-3, and downregulation of Bcl-2 at mRNA level, determining the anticancer effects of biosynthesized CuO nanoparticles through mitochondrial-mediated apoptosis signaling pathway. Therefore, based on the scientific achievements it can be concluded that fabricated CuO nanoparticles may be used in future studies to augment the activities of anticancer drugs in vivoand in clinical trials.

We consider a kind of site-dependent branching Brownian motions whose branching laws depend on the site-branching factor σ(·). We focus on the functional ergodic limits for the occupation time processes of the models in ℝ. It is proved that the limiting process has the form of λξ(·), where λis the Lebesgue measure on ℝ and ξ(·) is a real-valued process which is non-degenerate if and only if σis integrable. When ξ(·) is non-degenerate, it is strictly positive for t> 0. Moreover, ξconverges to 0 in finite-dimensional distributions if the integral of σtends to infinity.

The electrical transport behavior of SnS under high pressure has been investigated by the temperature dependence of electrical resistivity measurement, the in situ Hall-effect measurement, and the first-principle calculation. The experimental results show that SnS undergoes a semiconductor to semimetal transition at ∼10.3 GPa, and this transition is further substantiated by the band-structure calculation. The total and partial density of states predict that the semimetal character of SnS is attributed to the enhanced coupling of Sn-5s, Sn-5p, and S-3p states with application of pressure. In addition, dramatic changes in electrical transport parameters such as the electrical resistivity, the carrier concentration, and the carrier mobility are observed at 12.6 GPa, which are correlated to the pressure-induced Pnma-Cmcmstructural phase transition.

Most practical target tracking are usually maneuvering, while most target tracking algorithm are linear filter. More estimation error is introduced from linear filter. Nowadays more and more researchers pay their attention in Maneuvering Target Tracking algorithm. Particle filter has been developed for estimation of nonlinear system states. This paper presents an improved particle filter, which can apply the maneuvering target tracking problem. In practice, the particle filter would take abundant computation for estimate the maneuvering target tracking. The ChinaGrid system use the agile and distributed federations to reduce the computing time, which achieve to fast resolution for particle filter computation of target tracing application. Lastly the simulation proves it.

An alternate current impedance spectrum was utilized to differentiate the electrical transport process, respectively, in the bulk and the grain boundary of barium tungstate microcrystallines under high pressures up to 20 GPa. For powdered BaWO4microcrystallines, the grain boundary makes a more remarkable contribution than the bulk to the total resistance. The discontinuities of bulk resistance and relaxation frequency at about 7 and 14 GPa reflect the pressure-induced structural phase transitions of BaWO4from scheelite to fergusonite structure and from fergusonite to an unknown disordered structure, respectively. The activation energy of the grain boundary decreases with increasing pressure from 6.9 to 8.9 GPa, indicating that the compression has a negative contribution to the activation energy and the transport of charge carriers through the boundary becomes easier. The activation energy of the bulk also shows a similar phenomenon. In addition, the ascending relaxation frequency of the bulk and grain boundary shows that the polarization process needs much shorter time in the state of three-phase coexistence.

In this paper, a moderate deviation theorem for one-dimensional stable random walks in random scenery is proved. The proof relies on the analysis of maximum local times of stable random walks, and the comparison of moments between random walks in random scenery and self-intersection local times of the underlying random walks.

The high-pressure electrical transport behavior of microcrystalline tungsten trioxides (WO3) was investigated by direct current electrical resistivity measurement and alternate current impedance spectrum techniques in a diamond anvil cell up to 35.5 GPa. Discontinuous changes of electrical resistivity occurred during the pressure induced structure phase transitions at 1.8, 21.2, and 30.4 GPa. The irreversible resistivity reveals that the structure phase transition is not reversible. In addition, the abnormal changes of bulk resistance and transport activation energy at about 3 and 10 GPa are related to the isostructural phase transition reported by previous Raman study. The temperature induced resistivity change indicates that WO3is a semiconductor from ambient pressure to 25.3 GPa.

Abstract: Functional limit theorems for scaled occupation time fluctuations of a sequence of generalized branching particle systems in ℝ d with anisotropic space motions and strongly degenerated splitting abilities are studied in the cases of critical and intermediate dimensions. The results show that the limit processes are time-independent measure-valued Wiener processes with simple spatial structure.

Abstract: In this paper, some limit processes of occupation time fluctuations of the branching particle systems with varied branching laws from site to site are obtained. The results show that the varied branching laws can not affect the limit processes and the scaling parameters in the case of large dimensions, but in the case of critical dimensions, under suitable assumptions, it changes the limit processes with simple and isotropic spatial structures to those with complicated and anisotropic spatial structures and gives corrections in the scaling parameters. [Copyright &y& Elsevier]

We carried out the accurate in situ Hall-effect measurements, the temperature dependence of electrical resistivity measurements and the first-principles calculations in SnO under high pressure. The results of Hall-effect measurements display the carrier transport behavior of SnO under pressure, which indicates that SnO undergoes a carrier-type inversion around 1.3 GPa and an underlying phase transition at 2–3 GPa. In addition, the temperature dependence of electrical resistivity shows that SnO undergoes a semiconductor-to-metal transition around 5 GPa. The calculated band structures based on the first-principles method illustrate that the indirect band gap of SnO vanishes around 4 GPa. In particular, the results of total and partial density of states indicate that the closure of the indirect fundamental gap is mostly attributed to Sn-5s and 5p states hybridized with O-2p states at the Fermi level.

Abstract: In this paper, we prove approximations of multifractional Brownian motions with moving-average representations and of those with harmonizable representations in the space of continuous functions on [0, 1]. These approximations are constructed by Poisson processes.

Abstract: We provide a result on an approximation to the generalized multifractional Brownian motion in the space of continuous functions on [0, 1]. The construction of this approximation is based on the Poisson process. [Copyright &y& Elsevier]