Lignin contains abundant aromatic ring structures,which can be converted into green sustainable aviation fuelrange arenes through hydrodeoxygenation(HDO).A series of supported FeMoS/NC catalysts were synthesized by a ...Lignin contains abundant aromatic ring structures,which can be converted into green sustainable aviation fuelrange arenes through hydrodeoxygenation(HDO).A series of supported FeMoS/NC catalysts were synthesized by a hydrothermal method.The HDO performance of the catalysts was evaluated using 4-ethylguaiacol as a model compound at 340℃ under 3 MPa H2.The MoS_(2)/NC catalyst exhibited a deoxygenation degree of 83.4%,whereas the Fe-modified catalyst(Fe_(0.3)MoS/NC)attained complete deoxygenation(100%)with an arenes selectivity of 78.6%.Beyond the optimal ratio,the deoxygenation degree is inversely proportional to the Fe/Mo molar ratio.The catalysts were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),low-temperature nitrogen adsorption(BET method)and X-ray photoelectron spectroscopy(XPS).The characterization results indicated that the introduction of Fe enhanced the uniform dispersion of MoS_(2)on the NC support surface.This modification further increased the acidity of the catalyst surface and raised the concentration of sulfur vacancies,thereby promoting the adsorption of oxygencontaining compounds.Furthermore,the HDO performance of the Fe_(0.3)MoS/NC catalyst was evaluated using actual lignin as a feedstock under the conditions of 340℃,3 MPa H2 and 12 h.The results showed a green hydrocarbon yield of 65.5%,of which the C_(8)-C_(16)fraction accounted for 54.4%of the total hydrocarbons.Within this fraction,aromatic compounds constituted 63.4%,suggesting its potential use as green aviation fuel-range arenes.This work thus establishes a viable catalytic pathway for efficient conversion of lignin to arenes.展开更多
[Objectives]To analyze the evolutionary rates of mitochondrial protein-coding genes across five closely related species of fruit flies,thereby providing a foundation for the molecular identification of these quarantin...[Objectives]To analyze the evolutionary rates of mitochondrial protein-coding genes across five closely related species of fruit flies,thereby providing a foundation for the molecular identification of these quarantine pests.[Methods]The newly identified species Bactrocera latizona,along with its closely related species within the same subgenus,namely B.atrifemur,B.rubigina,B.thailandica,and B.tuberculata,were selected as the subjects of this study.Utilizing the complete mitochondrial genome sequences of these five fruit fly species,the Ka/Ks ratios of 13 protein-coding genes were calculated to assess their selective pressures and degrees of conservation.[Results]The mitochondrial genome lengths of the five fruit fly species ranged from 15603 to 15972 bp.The Ka/Ks ratios of the ND4L and ND4 genes for all species were generally elevated(values of the ND4L gene all exceeding 2),suggesting accelerated evolutionary rates.In contrast,the COX1 gene exhibited the lowest Ka/Ks ratio,indicating it is the most conserved gene among those analyzed.The majority of genes displayed Ka/Ks ratios below 1,implying they are under purifying selection.[Conclusions]Among the mitochondrial genes of five fruit fly species,COX1 is the most conserved,whereas ND4L exhibits the highest rate of evolution.These findings offer theoretical support for the development of molecular markers and the species identification of fruit flies.展开更多
The atmospheric corrosion behavior of 510L low alloy steel subjected to acid-cleaned surface(ACS)and eco-pickled surface(EPS)treatments is systematically examined.After 1 year of atmospheric exposure,both ACS-and EPS-...The atmospheric corrosion behavior of 510L low alloy steel subjected to acid-cleaned surface(ACS)and eco-pickled surface(EPS)treatments is systematically examined.After 1 year of atmospheric exposure,both ACS-and EPS-treated samples demonstrate protective ability index values exceeding 2,indicating robust protective properties of the developed rust layers.The corrosion rates of ACS-and EPS-treated samples are similar.During the initial corrosion stage,γ-FeOOH emerges as the dominant corrosion product.With the prolonged atmospheric exposure,γ-FeOOH content progressively decreases through phase transformation into thermodynamically stableα-FeOOH and densely structured Fe_(3)O_(4),which markedly suppresses the corrosion of the steel.Notably,the corrosion rate of the coated EPS sample is obviously lower than that of the coated ACS counterpart,which is ascribed to the distinctive micro-roughness of EPS-treated surfaces that promote mechanical interlocking with protective coatings.展开更多
Low heat input welding is widely used in the industry.The microstructure and toughness of the welded joints under low heat input conditions have received less attention than those under high heat input.The impact toug...Low heat input welding is widely used in the industry.The microstructure and toughness of the welded joints under low heat input conditions have received less attention than those under high heat input.The impact toughness,microstructure and failure mechanisms of the coarse-grain heat-affected zone(CGHAZ)in a micro-alloyed steel were investigated by welding thermal simulation with the heat input ranging from 15 to 65 kJ/cm.The impact toughness of CGHAZ is highly sensitive to variations in low heat input.The failure mechanisms were discussed from the viewpoints of micro-voids formation and micro-cracks propagation.The micro-voids are preferred to be formed and grow at soft phase of grain boundary ferrite(GBF).At the heat inputs no more than 22 kJ/cm,martensite was dominantly formed,and the micro-cracks initiated from the GBF were propagated into the grain interiors,leading to the brittle fracture and low toughness.When the heat input was increased to 31.2 kJ/cm,granular bainite became the dominant constitute,causing cracks to deflect away from GBF and propagate into prior austenite grains.The high density high-angle and low-angle grain boundaries and the presence of retained austenite,effectively restricted the crack propagation,resulting in ductile fracture behavior and enhanced toughness.High heat input(62.3 kJ/cm)promoted coarse GBF formation,providing continuous paths for microcrack propagation.This direct intergranular crack progression caused brittle fracture and low toughness.Industrial cold cracking in the CGHAZ can thus be controlled by heat input optimization to maximize toughness.展开更多
We demonstrate a high-speed rotating slit beam shaping method for femtosecond(fs)laser three-dimensional(3D)isotropic inscription in glass materials.By integrating fs laser direct writing with a real-time rotating sli...We demonstrate a high-speed rotating slit beam shaping method for femtosecond(fs)laser three-dimensional(3D)isotropic inscription in glass materials.By integrating fs laser direct writing with a real-time rotating slit mechanism,a 3D symmetric spherical focal field distribution is created in the laser-irradiated regions of transparent substrates.The corresponding focal field distribution is theoretically calculated and validated by examining the features of laser-inscribed lines in glass samples.Moreover,we investigate the influences of laser writing speed and slit rotational speed on the fabrication resolution in glass,and discuss the formation mechanism of the generated periodic microstructures.To showcase its powerful capability for3D isotropic fabrication,the high-speed rotating slit beam shaping method is applied to create straight optical waveguides,bending optical waveguides,and hollow microchannels in the glass.The proposed method holds great potential for the facile manufacture of diverse 3D isotropic microstructures and devices within transparent materials across various applications,including advanced photonics,microoptics,micro-electromechanical systems,and microfluidics.展开更多
Dear Editor,Linear and whorled nevoid hypermelanosis(LWNH)is a rare,sporadic pigmentary disorder characterized by hyperpigmented macules arranged in linear streaks and whorls along Blaschko's lines,typically appea...Dear Editor,Linear and whorled nevoid hypermelanosis(LWNH)is a rare,sporadic pigmentary disorder characterized by hyperpigmented macules arranged in linear streaks and whorls along Blaschko's lines,typically appearing within the first few weeks of life[1],and remains a challenge to treat.Here,we report a case of LWNH and review the relevant literature to help clinicians better understand this disease.展开更多
The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viabili...The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viability.Thermodynamic phase diagrams were developed to intuitively represent carbon deposition and carburization preferences in CH4-CO-H_(2) ternary atmospheres.High carbon potential and low oxygen potential significantly enhance carbon deposition and carburization.Increasing temperature from 500 to 1000℃ shifts the dominant reactions from CO-based to CH_(4)-based,increasing maximum carbon deposition from 0.55 to 0.80 mol and carburization from 0.25 to 0.80 mol per mole of reducing gas.Increasing pressure suppresses CH4-based reactions while promoting CO-based reactions,reducing maximum carbon deposition from 0.8 to~0.7 mol and increasing maximum carburization from 0.80 to 0.85 mol per mole of reducing gas.Equilibrium phase diagrams for various carbides were also developed,revealing preferences for Fe_(3)C_(2),Fe_(7)C_(3),Fe_(5)C_(2),and Fe_(3)C as the Fe/C ratio increases.Higher temperatures and CH_(4) concentrations favor the formation of carbides with higher carbon content.Carburization preferences under typical Energiron ZR and Midrex atmospheres were highlighted,and the higher carbon content in direct reduction iron produced by the Energiron ZR process was thermodynamically confirmed.展开更多
Mold electromagnetic stirring technology for optimizing the flow of molten steel is now widely used in the continuous casting production process of high-quality steels.However,studies on the case that the center of th...Mold electromagnetic stirring technology for optimizing the flow of molten steel is now widely used in the continuous casting production process of high-quality steels.However,studies on the case that the center of the electromagnetic stirrer is located outside the mold have not been reported.Herein,the effect of the electromagnetic stirrer centered outside the mold on the steel flow field was studied in detail by means of numerical simulations.A Gauss meter was used to measure the magnetic induction intensity at different positions,currents,and frequencies.The test results were compared with the simulation results of electromagnetic stirring to calibrate and verify the accuracy of the electromagnetic model.Then,electromagnetic force was introduced into the flow field model as a source term to study its effect on the flow field under anomalous conditions.The results show that when the center of the electromagnetic stirrer is located outside the mold,the magnetic field strength is about twice as strong as that located inside the mold.This also leads to an increase in the flow velocity near the electromagnetic stirrer.As a result,the optimal electromagnetic stirring parameters(200 A,2.5 Hz)were specified when the center of the electromagnetic stirrer is located outside the mold.展开更多
In recent years, most of the drilling engineering accidents are caused by human error of judgment, which has much to do with the fact that technical experts and leaders can't get to know the site situation immedia...In recent years, most of the drilling engineering accidents are caused by human error of judgment, which has much to do with the fact that technical experts and leaders can't get to know the site situation immediately and miss the best time to deal with downhole anomalies. Along the general direction of information-based drilling, relying on the continuous improvement of information construction and the maturing of engineering automatic warning software, in August 2016, our company was the first pilot unit of Great Wall Drilling to establish a remote technical support center. The remote real-time monitoring of drilling parameters, data entry and analysis of EISS system, engineering simulation calculation and analysis software and other modules were applied to construct a remote technical support system for drilling engineering, which achieved the control objectives of "pre-prediction", "in-process control" and "post-analysis", promoted the continuous improvement of ROP, steadily reduced the accident complexity rate, and promoted the overall speed-up and efficiency improvement of all well teams of the Company. At the same time, combining with my own work practice, the author puts forward optimization and expansion methods for the problems and development direction in the operation of the remote support system, hoping to provide reference and reference for more people in the industry.展开更多
Quantitative detection of trace small-sized nanoplastics(<100 nm)remains a significant challenge in surface-enhanced Raman scattering(SERS).To tackle this issue,we developed a hydrophobic CuO@Ag nanowire substrate ...Quantitative detection of trace small-sized nanoplastics(<100 nm)remains a significant challenge in surface-enhanced Raman scattering(SERS).To tackle this issue,we developed a hydrophobic CuO@Ag nanowire substrate and introduced a multiplex-feature analysis strategy based on the coffee ring effect.This substrate not only offers high Raman enhancement but also exhibits a high probability of detection(POD),enabling rapid and accurate identification of 50 nm polystyrene nanoplastics over a broad concentration range(1–10−10 wt%).Importantly,experimental results reveal a strong correlation between the coffee ring formation and the concentration of nanoplastic dispersion.By incorporating Raman signal intensity,coffee ring diameter,and POD as combined features,we established a machine learning-based mapping between nanoplastic concentration and coffee ring characteristics,allowing precise predictions of dispersion concentration.The mean squared error of these predictions is remarkably low,ranging from 0.21 to 0.54,representing a 19 fold improvement in accuracy compared to traditional linear regression-based methods.This strategy effectively integrates SERS with wettability modification techniques,ensuring high sensitivity and fingerprinting capabilities,while addressing the limitations of Raman signal intensity in accurately reflecting concentration changes at ultra-low levels,providing a new idea for precise SERS measurements of nanoplastics.展开更多
In the context of power generation companies, vast amounts of specialized data and expert knowledge have been accumulated. However, challenges such as data silos and fragmented knowledge hinder the effective utilizati...In the context of power generation companies, vast amounts of specialized data and expert knowledge have been accumulated. However, challenges such as data silos and fragmented knowledge hinder the effective utilization of this information. This study proposes a novel framework for intelligent Question-and-Answer (Q&A) systems based on Retrieval-Augmented Generation (RAG) to address these issues. The system efficiently acquires domain-specific knowledge by leveraging external databases, including Relational Databases (RDBs) and graph databases, without additional fine-tuning for Large Language Models (LLMs). Crucially, the framework integrates a Dynamic Knowledge Base Updating Mechanism (DKBUM) and a Weighted Context-Aware Similarity (WCAS) method to enhance retrieval accuracy and mitigate inherent limitations of LLMs, such as hallucinations and lack of specialization. Additionally, the proposed DKBUM dynamically adjusts knowledge weights within the database, ensuring that the most recent and relevant information is utilized, while WCAS refines the alignment between queries and knowledge items by enhanced context understanding. Experimental validation demonstrates that the system can generate timely, accurate, and context-sensitive responses, making it a robust solution for managing complex business logic in specialized industries.展开更多
ZnAl_(2)O_(4) and ZnAl_(2)O_(4)-based ceramics have attracted much attention from researchers due to their good microwave dielectric,thermal and mechanical properties.In this work,the influence of 5%(in mass)CuO-TiO_(...ZnAl_(2)O_(4) and ZnAl_(2)O_(4)-based ceramics have attracted much attention from researchers due to their good microwave dielectric,thermal and mechanical properties.In this work,the influence of 5%(in mass)CuO-TiO_(2)-Nb_(2)O_(5)(CTN)ternary composite oxide additives with different composition ratios on sintering behavior and properties of ZnAl_(2)O_(4) microwave dielectric ceramics was investigated.When the molar fraction ranges of Cu,Ti and Nb elements in 5%CTN additives are 0.625-0.875,0-0.250 and 0.125-0.625,respectively,sintering temperature of ZnAl_(2)O_(4) ceramics can be reduced from above 1400℃to below 1000℃.The sintering additives CN(Cu:Nb=1:1,molar ratio)and CTN(Cu:Ti:Nb=4:1:3,molar ratio)can reduce sintering temperature of ZnAl_(2)O_(4) ceramics to 975 and 1000℃,respectively,while maintaining good dielectric properties(dielectric constantε_(r)=11.36,quality factor Q׃=8245 GHz andε_(r)=9.52,Q׃=22249 GHz)and flexural strengths(200 and 161 MPa),which are expected to be applied in preparation of low temperature co-fired ceramic(LTCC)materials with copper electrodes.Low-temperature sintering of the ZnAl_(2)O_(4)+CTN system is characterized as activated sintering.Nanometer-level amorphous interfacial films containing Cu,Ti,and Nb elements are observed at the grain boundaries,which may provide fast diffusion pathways for mass transportation during the sintering process.Valence changes of Ti and Cu ions,along with changes of oxygen vacancies,are confirmed,which provides a potential mechanism for reduced sintering temperature of ZnAl_(2)O_(4) ceramics.In addition,a series of reactions occurring at the grain boundaries can activate these boundaries and further promote the sintering densification process.These results suggest a promising way to design a novel LTCC material with excellent properties based on the low temperature sintering of ceramics with the sintering aid of CuO-TiO_(2)-Nb_(2)O_(5) composite oxide.展开更多
The proper flowering time of rose(Rosa hybrida)is vital for the market value of this horticultural crop,but the mechanism regulating this trait is largely unclear.Here,we found that the transcription factor SQUAMOSA P...The proper flowering time of rose(Rosa hybrida)is vital for the market value of this horticultural crop,but the mechanism regulating this trait is largely unclear.Here,we found that the transcription factor SQUAMOSA PROMOTER BINDING PROTEIN-LIKE4(RhSPL4)positively regulates flowering time in rose.Transient silencing or overexpression transgenic rose plants of RhSPL4 exhibited delayed or early flowering,respectively.Analysis of transcriptome data from transgenic lines overexpressing RhSPL4 compared to the wild type indicated that differentially expressed genes were significantly enriched in the circadian rhythm pathway.Among the proteins encoded by these genes,RhSPL4 binds to the promoter of PSEUDO-RESPONSE REGULATOR 5-LIKE(RhPRR5L),as revealed in yeast one-hybrid,dual-Luciferase/Renilla luciferase reporter,chromatin immunoprecipitation-quantitative PCR and electrophoretic mobility shift assay.Furthermore,RhSPL4 specifically binds to the478 to441 bp region of the RhPRR5L promoter and activates its transcription.The silencing of RhPRR5L delayed flowering time in rose,resembling the phenotype of RhSPL4-silenced plants.Together,these results indicate that the RhSPL4-RhPRR5L module positively regulates flowering time in rose,laying the foundation for the genetic improvement of flowering time in this important horticultural crop.展开更多
Cutibacterium acnes were used to induce lipase production,and to establish ex-vivo skin model of inflammatory response and post-inflammatory hyperpigmentation,in purpose of exploring the mechanism of chamomilla recuti...Cutibacterium acnes were used to induce lipase production,and to establish ex-vivo skin model of inflammatory response and post-inflammatory hyperpigmentation,in purpose of exploring the mechanism of chamomilla recutita extract.Clinical study was designed to investigate the effects of chamomilla recutita extract on Chinese volunteers with sequelae of adult acne,by evaluating the severity of acne,post-acne erythema and pigmentation,skin basic physiological conditions.The results showed that chamomilla recutita extract inhibited lipase activity,cellular inflammatory response,and melanin production.In the clinical study,the acnes were relieved 173%,with a 78%lower post-acne erythema index and 202%less hyperpigmentation as compared to placebo,after applying samples containing 1%chamomilla recutita extract for 28 days.Meanwhile,chamomilla recutita extract showed instant oil control effect.The extract significantly reduced sebum secretion by 293%,increased skin moisture content by 102%,and strengthened the skin barrier by 193%after 28 days application,which provided favorable skin physiological basis for the prevention and improvement of acne vulgaris and sequelae.展开更多
Multi-resonance thermally ac-tivated delayed fluorescence(MR-TADF)emitters are one of the most excellent materi-als for high performance or-ganic light-emitting diodes(OLEDs)with high color puri-ty benefiting from the...Multi-resonance thermally ac-tivated delayed fluorescence(MR-TADF)emitters are one of the most excellent materi-als for high performance or-ganic light-emitting diodes(OLEDs)with high color puri-ty benefiting from their nar-row full width at half maxi-mum(FWHM)and great de-vice performance.However,small spin-orbit coupling(SOC)is one of drawbacks for MR-TADF emitters and introduction of heavy atoms may be one effective solution.In this work,four MR-TADF molecules with different atoms(O,S,Se)are carried out based on the first-principles calculation,and excited state dynamics in both toluene and solid phase is investi-gated.Our calculation results indicate that heavy atoms could induce smaller adiabatic ener-gy gap and larger SOC between the first singlet excited state and the first triplet excited state,which is advantageous for the conversion of singlet and triplet excitons,and thus the generation of thermally activated delayed fluorescence(TADF).Though the reorganization energy and full width at half maximum(FWHM)of emission are increased,the influence is quite limited.Besides,the fluorescent rates are also little influenced.Our calculation results indicate that heavy atom introduction is an efficient strategy to enhance the SOC values of MR-TADF emitters without influencing other properties significantly.展开更多
A theory based on the superposition principle is developed to uncover the basic physics of wave behavior in a finite grating of N unit cells.The theory reveals that bound states in the continuum(BICs)of infinite quali...A theory based on the superposition principle is developed to uncover the basic physics of wave behavior in a finite grating of N unit cells.The theory reveals that bound states in the continuum(BICs)of infinite quality factor(Q-factor)can be supported by such a grating when perfect reflection is introduced at its boundaries.If geometrical perturbations are introduced into the structure,the dark BICs transform into bright quasi-BICs with finite Q-factor,maintaining spectral characteristics nearly identical to those of quasi-BICs supported by infinite gratings.When the boundaries are replaced with high-reflectivity metallic mirrors,the Q-factor of the resonant mode is reduced to be finite;however,it can be much larger than that in the corresponding nanostructure with open boundaries and can be tuned over a large range by varying the number of unit cells or boundary conditions.展开更多
Ruthenium(Ru)-based chalcogenide(S,Se)is a promising material in various fields,such as optics,photoelectrodes,and electrocatalysis,owing to its suitable bandgap for generating charge carriers under light illumination...Ruthenium(Ru)-based chalcogenide(S,Se)is a promising material in various fields,such as optics,photoelectrodes,and electrocatalysis,owing to its suitable bandgap for generating charge carriers under light illumination ranging from visible to near-infrared(NIR)and its high absorption coefficient.In this study,we report the synthesis of Ru Se_(2)thin films by chemical vapor deposition(CVD)with a bandgap matching the NIR region at 0.52 e V.Further,we demonstrated Ru S_(2x)Se_(2-2x)alloy films using the post-sulfurization process after CVD Ru Se_(2)with a tunable bandgap from 0.52 to 1.39 e V depending on sulfur composition.Remarkably,Ru S_(2x)Se_(2-2x)alloy film metal–semiconductor–metal(MSM)photodetector sulfurized at 500°C,with a 0.75 e V bandgap,exhibits enhanced broad absorption across NIR spectral ranges,suppressed dark current and high photoresponsivity in NIR wavelengths range even at zero-bias.We believe the bandgaptunable Ru S_(2x)Se_(2-2x)thin film through an efficient deposition method could be suitable for various optoelectronic applications.展开更多
Once a train stops in a tunnel section and requires emergency evacuation,the large distance between stations and long walking distances in the underground spaces of suburban railway systems pose potential risks to the...Once a train stops in a tunnel section and requires emergency evacuation,the large distance between stations and long walking distances in the underground spaces of suburban railway systems pose potential risks to the evacuation process on tunnel platforms,especially in complex environments.This study utilized Virtual Reality(VR)technology to construct a virtual experimental platform for tunnel evacuation in suburban railway systems,simulating different combinations of smoke and obstacle conditions.By requiring participants to wear VR glasses and walk on an omnidirectional treadmill for moving,as well as complete psychological questionnaires,the study reveals the influences of No Guiding(NG)signs,Wall-Guided(WG)signs,and Central axis Guidance(CG)signs on the movement abilities and psychological behaviors of participants contrastively.The results show that either smoke conditions or obstacle positions affect the mental stress of participants,and the guidance sign has a positive effect on reducing the mental stress.There is an inverse relationship between mental stress and movement abilities.WG and CG signs respectively lead participants to walk closer to walls and along the central axis,which is conducive to reducing the variation in participants’behavior characteristics when circumventing obstacles on the wall side or track side under smoke conditions,respectively.Additionally,CG signs reduce the speed fluctuations of participants before circumventing obstacles,improving the stability of the distance from the wall and speed under smoke conditions,compared to NG and WG signs.These findings contribute to understanding the evacuation psychological-behavioral-movement characteristics of pedestrians on evacuation platforms in suburban railway tunnels and provide a basis for improving the safety design of evacuation guidance signs.展开更多
The forming processes of 4,40-dipyridyl-based single-molecule junctions and mechanically induced conductance switching as well as the side-group effects are systematically investigated by applying the ab initio-based ...The forming processes of 4,40-dipyridyl-based single-molecule junctions and mechanically induced conductance switching as well as the side-group effects are systematically investigated by applying the ab initio-based adiabatic geometric optimization method and the one-dimensional transmission combined with three-dimensional correction approximation(OTCTCA)method.The numerical results show that for the 4,40-dipyridyl with a p-conjugated phenyl-phosphoryl or diphenylsilyl side group,the pyridyl vertically anchors on the second atomic layer of the pyramid-shaped Au tip electrode at small inter-electrode distances by laterally pushing the apical Au atom aside,which induces stronger pyridyl-electrode coupling and high-conductance state of the formed junctions.As the inter-electrode distance increases,the pyridyl shifts to the apical Au atom of the tip electrode.This apical Au atom introduces additional scatterings to the tunneling electrons and significantly decreases the conductance of the junctions.Furthermore,for the 4,40-dipyridyl with a phenyl-phosphoryl side group,the probability of manifesting the high-conductance state is decreased due to the oxygen atom reducing the probability of the pyridyl adsorbing on the second layer of Au tip electrode.In contrast,for the 4,40-dipyridyl with a nonconjugated cyclohexyl-phosphoryl side group,the steric hindrance from the bulky cyclohexyl group leads the molecule to preferentially form the O-Au contact,which prevents both the high conductance and mechanically induced conductance switching of the junction.Our results provide a theoretical understanding of the side-group effects on electronic transport properties of single-molecule junctions,offering an alternative explanation for the experimental observations.展开更多
Sine-wave drive and square-wave drive are two common motor control strategies.This study constructs a mathematical model capable of predicting the distribution of electromagnetic force waves in synchronous reluctance ...Sine-wave drive and square-wave drive are two common motor control strategies.This study constructs a mathematical model capable of predicting the distribution of electromagnetic force waves in synchronous reluctance motors(SynRMs)under these two drive methods,and comparatively analyzes the vibration phenomena induced by electromagnetic forces under different drive methods.It aims to provide an effective tool for predicting the distribution of electromagnetic force waves in SynRMs,while exploring the influence of drive modes on their vibration characteristics.The study focuses on a 4-pole,36-slot 5.5 kW SynRM.Based on the magnetomotive force(MMF)-permeance method,incorporating the special rotor structure and the characteristics of current harmonics under square-wave drive,an air-gap flux distribution function is established.Meanwhile,Maxwell’s stress tensor method is adopted to analyze how the air-gap flux density relates to electromagnetic excitation force waves.Subsequently,this analysis is applied to forecast the spatiotemporal distribution features of radial electromagnetic force waves.Finite element simulations are conducted to compute the modal and vibration responses of the SynRM,followed by a comparative analysis of the vibration characteristics under the two drive methods.Additionally,a 6-pole,36-slot SynRM is used for additional comparative verification.Ultimately,the effectiveness of the simulation results is verified through experiments.展开更多
基金Supported by grants from National Key Research and Development Program of China(2024YFB4205903)the National Natural Science Foundation of China(52274308,U22B20144,22278440 and 22078362)Shandong Provincial Technology Innovation Guidance Plan(YDZX2023060)。
文摘Lignin contains abundant aromatic ring structures,which can be converted into green sustainable aviation fuelrange arenes through hydrodeoxygenation(HDO).A series of supported FeMoS/NC catalysts were synthesized by a hydrothermal method.The HDO performance of the catalysts was evaluated using 4-ethylguaiacol as a model compound at 340℃ under 3 MPa H2.The MoS_(2)/NC catalyst exhibited a deoxygenation degree of 83.4%,whereas the Fe-modified catalyst(Fe_(0.3)MoS/NC)attained complete deoxygenation(100%)with an arenes selectivity of 78.6%.Beyond the optimal ratio,the deoxygenation degree is inversely proportional to the Fe/Mo molar ratio.The catalysts were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),low-temperature nitrogen adsorption(BET method)and X-ray photoelectron spectroscopy(XPS).The characterization results indicated that the introduction of Fe enhanced the uniform dispersion of MoS_(2)on the NC support surface.This modification further increased the acidity of the catalyst surface and raised the concentration of sulfur vacancies,thereby promoting the adsorption of oxygencontaining compounds.Furthermore,the HDO performance of the Fe_(0.3)MoS/NC catalyst was evaluated using actual lignin as a feedstock under the conditions of 340℃,3 MPa H2 and 12 h.The results showed a green hydrocarbon yield of 65.5%,of which the C_(8)-C_(16)fraction accounted for 54.4%of the total hydrocarbons.Within this fraction,aromatic compounds constituted 63.4%,suggesting its potential use as green aviation fuel-range arenes.This work thus establishes a viable catalytic pathway for efficient conversion of lignin to arenes.
文摘[Objectives]To analyze the evolutionary rates of mitochondrial protein-coding genes across five closely related species of fruit flies,thereby providing a foundation for the molecular identification of these quarantine pests.[Methods]The newly identified species Bactrocera latizona,along with its closely related species within the same subgenus,namely B.atrifemur,B.rubigina,B.thailandica,and B.tuberculata,were selected as the subjects of this study.Utilizing the complete mitochondrial genome sequences of these five fruit fly species,the Ka/Ks ratios of 13 protein-coding genes were calculated to assess their selective pressures and degrees of conservation.[Results]The mitochondrial genome lengths of the five fruit fly species ranged from 15603 to 15972 bp.The Ka/Ks ratios of the ND4L and ND4 genes for all species were generally elevated(values of the ND4L gene all exceeding 2),suggesting accelerated evolutionary rates.In contrast,the COX1 gene exhibited the lowest Ka/Ks ratio,indicating it is the most conserved gene among those analyzed.The majority of genes displayed Ka/Ks ratios below 1,implying they are under purifying selection.[Conclusions]Among the mitochondrial genes of five fruit fly species,COX1 is the most conserved,whereas ND4L exhibits the highest rate of evolution.These findings offer theoretical support for the development of molecular markers and the species identification of fruit flies.
基金support by National Natural Science Foundation of China(Grant No.52401103)Key Scientific Research Project in Shanxi Province(Grant No.202302050201015)+3 种基金Central Guiding Science and Technology Development of Local Fund(Grant No.YDZJSK20231A046)the Special Fund for Science and Technology Innovation Teams of Shanxi Province(202204051001004)Science and Technology Cooperation and Exchange Special Project of Shanxi Province(202404041101038)Postgraduate Education Innovation Project of Shanxi Province(Grant No.2024SJ304).
文摘The atmospheric corrosion behavior of 510L low alloy steel subjected to acid-cleaned surface(ACS)and eco-pickled surface(EPS)treatments is systematically examined.After 1 year of atmospheric exposure,both ACS-and EPS-treated samples demonstrate protective ability index values exceeding 2,indicating robust protective properties of the developed rust layers.The corrosion rates of ACS-and EPS-treated samples are similar.During the initial corrosion stage,γ-FeOOH emerges as the dominant corrosion product.With the prolonged atmospheric exposure,γ-FeOOH content progressively decreases through phase transformation into thermodynamically stableα-FeOOH and densely structured Fe_(3)O_(4),which markedly suppresses the corrosion of the steel.Notably,the corrosion rate of the coated EPS sample is obviously lower than that of the coated ACS counterpart,which is ascribed to the distinctive micro-roughness of EPS-treated surfaces that promote mechanical interlocking with protective coatings.
基金supported by the National Natural Science Foundation of China(No.51804232)Beijing Municipal Natural Science Foundation(No.2212041)+1 种基金supported by the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(FRF-IDRY-20-020)GIMRT Program of the Institute for Materials Research,Tohoku University(202303-RDKGE-0518).
文摘Low heat input welding is widely used in the industry.The microstructure and toughness of the welded joints under low heat input conditions have received less attention than those under high heat input.The impact toughness,microstructure and failure mechanisms of the coarse-grain heat-affected zone(CGHAZ)in a micro-alloyed steel were investigated by welding thermal simulation with the heat input ranging from 15 to 65 kJ/cm.The impact toughness of CGHAZ is highly sensitive to variations in low heat input.The failure mechanisms were discussed from the viewpoints of micro-voids formation and micro-cracks propagation.The micro-voids are preferred to be formed and grow at soft phase of grain boundary ferrite(GBF).At the heat inputs no more than 22 kJ/cm,martensite was dominantly formed,and the micro-cracks initiated from the GBF were propagated into the grain interiors,leading to the brittle fracture and low toughness.When the heat input was increased to 31.2 kJ/cm,granular bainite became the dominant constitute,causing cracks to deflect away from GBF and propagate into prior austenite grains.The high density high-angle and low-angle grain boundaries and the presence of retained austenite,effectively restricted the crack propagation,resulting in ductile fracture behavior and enhanced toughness.High heat input(62.3 kJ/cm)promoted coarse GBF formation,providing continuous paths for microcrack propagation.This direct intergranular crack progression caused brittle fracture and low toughness.Industrial cold cracking in the CGHAZ can thus be controlled by heat input optimization to maximize toughness.
基金supported by the National Key Research and Development Program of China(2022YFA1404800)National Natural Science Foundation of China(12174107,12004221,12192254,92250304,W2441005,12334014,12192251)+4 种基金Natural Science Foundation of Shandong Province(ZR2024QA024,ZR2021ZD02)Postdoctoral Innovation Talents Support Program of Shandong Province(No.SDBX2019005)Shanghai Municipal Science and Technology Major ProjectFundamental Research Funds for the Central UniversitiesEngineering Research Center for Nanophotonics&Advanced Instrument,Ministry of Education,East China Normal University(No.2023nmc005)。
文摘We demonstrate a high-speed rotating slit beam shaping method for femtosecond(fs)laser three-dimensional(3D)isotropic inscription in glass materials.By integrating fs laser direct writing with a real-time rotating slit mechanism,a 3D symmetric spherical focal field distribution is created in the laser-irradiated regions of transparent substrates.The corresponding focal field distribution is theoretically calculated and validated by examining the features of laser-inscribed lines in glass samples.Moreover,we investigate the influences of laser writing speed and slit rotational speed on the fabrication resolution in glass,and discuss the formation mechanism of the generated periodic microstructures.To showcase its powerful capability for3D isotropic fabrication,the high-speed rotating slit beam shaping method is applied to create straight optical waveguides,bending optical waveguides,and hollow microchannels in the glass.The proposed method holds great potential for the facile manufacture of diverse 3D isotropic microstructures and devices within transparent materials across various applications,including advanced photonics,microoptics,micro-electromechanical systems,and microfluidics.
文摘Dear Editor,Linear and whorled nevoid hypermelanosis(LWNH)is a rare,sporadic pigmentary disorder characterized by hyperpigmented macules arranged in linear streaks and whorls along Blaschko's lines,typically appearing within the first few weeks of life[1],and remains a challenge to treat.Here,we report a case of LWNH and review the relevant literature to help clinicians better understand this disease.
基金the financial support from the National Key R&D Program of China(No.2024YFC2910800)National Natural Science Foundation of China(52404336)+6 种基金China Postdoctoral Science Foundation(2024M750176)Postdoctoral Fellowship Program of CPSF(GZC20240109)the Young Elite Scientist Sponsorship Program by CAST(YESS20210090)Beijing Natural Science Foundation(J210017)the Project of SKLAM(No.KF24-14)China Baowu Low Carbon Metallurgical Technology Innovation Fund under Grant No.20210901Anhui Major Industrial Innovation Program under Contract No.AHZDCYCX-LSDT2023-01.
文摘The direct reduction process can reduce carbon emissions by over 50%compared to traditional blast furnace ironmaking.Carbon deposition and carburization are critical for ensuring process stability and economic viability.Thermodynamic phase diagrams were developed to intuitively represent carbon deposition and carburization preferences in CH4-CO-H_(2) ternary atmospheres.High carbon potential and low oxygen potential significantly enhance carbon deposition and carburization.Increasing temperature from 500 to 1000℃ shifts the dominant reactions from CO-based to CH_(4)-based,increasing maximum carbon deposition from 0.55 to 0.80 mol and carburization from 0.25 to 0.80 mol per mole of reducing gas.Increasing pressure suppresses CH4-based reactions while promoting CO-based reactions,reducing maximum carbon deposition from 0.8 to~0.7 mol and increasing maximum carburization from 0.80 to 0.85 mol per mole of reducing gas.Equilibrium phase diagrams for various carbides were also developed,revealing preferences for Fe_(3)C_(2),Fe_(7)C_(3),Fe_(5)C_(2),and Fe_(3)C as the Fe/C ratio increases.Higher temperatures and CH_(4) concentrations favor the formation of carbides with higher carbon content.Carburization preferences under typical Energiron ZR and Midrex atmospheres were highlighted,and the higher carbon content in direct reduction iron produced by the Energiron ZR process was thermodynamically confirmed.
基金The present work was financially supported by the China Postdoctoral Science Foundation(No.2023M730230)Special Funding Projects for Local Science and Technology Development guided by the Central Committee(No.YDZJSX2022C028)Fundamental Research Funds for the Central Universities(No.FRF-TP-22-053A1).
文摘Mold electromagnetic stirring technology for optimizing the flow of molten steel is now widely used in the continuous casting production process of high-quality steels.However,studies on the case that the center of the electromagnetic stirrer is located outside the mold have not been reported.Herein,the effect of the electromagnetic stirrer centered outside the mold on the steel flow field was studied in detail by means of numerical simulations.A Gauss meter was used to measure the magnetic induction intensity at different positions,currents,and frequencies.The test results were compared with the simulation results of electromagnetic stirring to calibrate and verify the accuracy of the electromagnetic model.Then,electromagnetic force was introduced into the flow field model as a source term to study its effect on the flow field under anomalous conditions.The results show that when the center of the electromagnetic stirrer is located outside the mold,the magnetic field strength is about twice as strong as that located inside the mold.This also leads to an increase in the flow velocity near the electromagnetic stirrer.As a result,the optimal electromagnetic stirring parameters(200 A,2.5 Hz)were specified when the center of the electromagnetic stirrer is located outside the mold.
文摘In recent years, most of the drilling engineering accidents are caused by human error of judgment, which has much to do with the fact that technical experts and leaders can't get to know the site situation immediately and miss the best time to deal with downhole anomalies. Along the general direction of information-based drilling, relying on the continuous improvement of information construction and the maturing of engineering automatic warning software, in August 2016, our company was the first pilot unit of Great Wall Drilling to establish a remote technical support center. The remote real-time monitoring of drilling parameters, data entry and analysis of EISS system, engineering simulation calculation and analysis software and other modules were applied to construct a remote technical support system for drilling engineering, which achieved the control objectives of "pre-prediction", "in-process control" and "post-analysis", promoted the continuous improvement of ROP, steadily reduced the accident complexity rate, and promoted the overall speed-up and efficiency improvement of all well teams of the Company. At the same time, combining with my own work practice, the author puts forward optimization and expansion methods for the problems and development direction in the operation of the remote support system, hoping to provide reference and reference for more people in the industry.
基金the National Natural Science Foundation of China(No.12174229 and 22375117)Natural Science Foundation of Shandong Province(No.ZR2022YQ02 and ZR2023MB149)Taishan Scholars Program of Shandong Province(No.tsqn202306152)for financial support.
文摘Quantitative detection of trace small-sized nanoplastics(<100 nm)remains a significant challenge in surface-enhanced Raman scattering(SERS).To tackle this issue,we developed a hydrophobic CuO@Ag nanowire substrate and introduced a multiplex-feature analysis strategy based on the coffee ring effect.This substrate not only offers high Raman enhancement but also exhibits a high probability of detection(POD),enabling rapid and accurate identification of 50 nm polystyrene nanoplastics over a broad concentration range(1–10−10 wt%).Importantly,experimental results reveal a strong correlation between the coffee ring formation and the concentration of nanoplastic dispersion.By incorporating Raman signal intensity,coffee ring diameter,and POD as combined features,we established a machine learning-based mapping between nanoplastic concentration and coffee ring characteristics,allowing precise predictions of dispersion concentration.The mean squared error of these predictions is remarkably low,ranging from 0.21 to 0.54,representing a 19 fold improvement in accuracy compared to traditional linear regression-based methods.This strategy effectively integrates SERS with wettability modification techniques,ensuring high sensitivity and fingerprinting capabilities,while addressing the limitations of Raman signal intensity in accurately reflecting concentration changes at ultra-low levels,providing a new idea for precise SERS measurements of nanoplastics.
文摘In the context of power generation companies, vast amounts of specialized data and expert knowledge have been accumulated. However, challenges such as data silos and fragmented knowledge hinder the effective utilization of this information. This study proposes a novel framework for intelligent Question-and-Answer (Q&A) systems based on Retrieval-Augmented Generation (RAG) to address these issues. The system efficiently acquires domain-specific knowledge by leveraging external databases, including Relational Databases (RDBs) and graph databases, without additional fine-tuning for Large Language Models (LLMs). Crucially, the framework integrates a Dynamic Knowledge Base Updating Mechanism (DKBUM) and a Weighted Context-Aware Similarity (WCAS) method to enhance retrieval accuracy and mitigate inherent limitations of LLMs, such as hallucinations and lack of specialization. Additionally, the proposed DKBUM dynamically adjusts knowledge weights within the database, ensuring that the most recent and relevant information is utilized, while WCAS refines the alignment between queries and knowledge items by enhanced context understanding. Experimental validation demonstrates that the system can generate timely, accurate, and context-sensitive responses, making it a robust solution for managing complex business logic in specialized industries.
基金National Natural Science Foundation of China (U24A2052)Shanghai Eastern Talent Plan。
文摘ZnAl_(2)O_(4) and ZnAl_(2)O_(4)-based ceramics have attracted much attention from researchers due to their good microwave dielectric,thermal and mechanical properties.In this work,the influence of 5%(in mass)CuO-TiO_(2)-Nb_(2)O_(5)(CTN)ternary composite oxide additives with different composition ratios on sintering behavior and properties of ZnAl_(2)O_(4) microwave dielectric ceramics was investigated.When the molar fraction ranges of Cu,Ti and Nb elements in 5%CTN additives are 0.625-0.875,0-0.250 and 0.125-0.625,respectively,sintering temperature of ZnAl_(2)O_(4) ceramics can be reduced from above 1400℃to below 1000℃.The sintering additives CN(Cu:Nb=1:1,molar ratio)and CTN(Cu:Ti:Nb=4:1:3,molar ratio)can reduce sintering temperature of ZnAl_(2)O_(4) ceramics to 975 and 1000℃,respectively,while maintaining good dielectric properties(dielectric constantε_(r)=11.36,quality factor Q׃=8245 GHz andε_(r)=9.52,Q׃=22249 GHz)and flexural strengths(200 and 161 MPa),which are expected to be applied in preparation of low temperature co-fired ceramic(LTCC)materials with copper electrodes.Low-temperature sintering of the ZnAl_(2)O_(4)+CTN system is characterized as activated sintering.Nanometer-level amorphous interfacial films containing Cu,Ti,and Nb elements are observed at the grain boundaries,which may provide fast diffusion pathways for mass transportation during the sintering process.Valence changes of Ti and Cu ions,along with changes of oxygen vacancies,are confirmed,which provides a potential mechanism for reduced sintering temperature of ZnAl_(2)O_(4) ceramics.In addition,a series of reactions occurring at the grain boundaries can activate these boundaries and further promote the sintering densification process.These results suggest a promising way to design a novel LTCC material with excellent properties based on the low temperature sintering of ceramics with the sintering aid of CuO-TiO_(2)-Nb_(2)O_(5) composite oxide.
基金supported by Yunnan Province Agricultural Joint Key Project(Grant No.202401BD070001-016)the National Natural Science Foundation of China(Grant No.32202530)+3 种基金Talent Introduction and Training Project of Yunnan Academy of Agricultural Sciences(Grant No.2024RCYP-09)Fundamental Research Project(Grant No.202401CF070046)Xingdian Talent support program(XDYC-QNRC-2023-0457)Yunnan Technology Innovation Center of Flower Technique.
文摘The proper flowering time of rose(Rosa hybrida)is vital for the market value of this horticultural crop,but the mechanism regulating this trait is largely unclear.Here,we found that the transcription factor SQUAMOSA PROMOTER BINDING PROTEIN-LIKE4(RhSPL4)positively regulates flowering time in rose.Transient silencing or overexpression transgenic rose plants of RhSPL4 exhibited delayed or early flowering,respectively.Analysis of transcriptome data from transgenic lines overexpressing RhSPL4 compared to the wild type indicated that differentially expressed genes were significantly enriched in the circadian rhythm pathway.Among the proteins encoded by these genes,RhSPL4 binds to the promoter of PSEUDO-RESPONSE REGULATOR 5-LIKE(RhPRR5L),as revealed in yeast one-hybrid,dual-Luciferase/Renilla luciferase reporter,chromatin immunoprecipitation-quantitative PCR and electrophoretic mobility shift assay.Furthermore,RhSPL4 specifically binds to the478 to441 bp region of the RhPRR5L promoter and activates its transcription.The silencing of RhPRR5L delayed flowering time in rose,resembling the phenotype of RhSPL4-silenced plants.Together,these results indicate that the RhSPL4-RhPRR5L module positively regulates flowering time in rose,laying the foundation for the genetic improvement of flowering time in this important horticultural crop.
文摘Cutibacterium acnes were used to induce lipase production,and to establish ex-vivo skin model of inflammatory response and post-inflammatory hyperpigmentation,in purpose of exploring the mechanism of chamomilla recutita extract.Clinical study was designed to investigate the effects of chamomilla recutita extract on Chinese volunteers with sequelae of adult acne,by evaluating the severity of acne,post-acne erythema and pigmentation,skin basic physiological conditions.The results showed that chamomilla recutita extract inhibited lipase activity,cellular inflammatory response,and melanin production.In the clinical study,the acnes were relieved 173%,with a 78%lower post-acne erythema index and 202%less hyperpigmentation as compared to placebo,after applying samples containing 1%chamomilla recutita extract for 28 days.Meanwhile,chamomilla recutita extract showed instant oil control effect.The extract significantly reduced sebum secretion by 293%,increased skin moisture content by 102%,and strengthened the skin barrier by 193%after 28 days application,which provided favorable skin physiological basis for the prevention and improvement of acne vulgaris and sequelae.
基金supported by the National Natural Science Foundation of China(No.11974216,No.12374269)the support of the Taishan Scholar Project of Shandong Province。
文摘Multi-resonance thermally ac-tivated delayed fluorescence(MR-TADF)emitters are one of the most excellent materi-als for high performance or-ganic light-emitting diodes(OLEDs)with high color puri-ty benefiting from their nar-row full width at half maxi-mum(FWHM)and great de-vice performance.However,small spin-orbit coupling(SOC)is one of drawbacks for MR-TADF emitters and introduction of heavy atoms may be one effective solution.In this work,four MR-TADF molecules with different atoms(O,S,Se)are carried out based on the first-principles calculation,and excited state dynamics in both toluene and solid phase is investi-gated.Our calculation results indicate that heavy atoms could induce smaller adiabatic ener-gy gap and larger SOC between the first singlet excited state and the first triplet excited state,which is advantageous for the conversion of singlet and triplet excitons,and thus the generation of thermally activated delayed fluorescence(TADF).Though the reorganization energy and full width at half maximum(FWHM)of emission are increased,the influence is quite limited.Besides,the fluorescent rates are also little influenced.Our calculation results indicate that heavy atom introduction is an efficient strategy to enhance the SOC values of MR-TADF emitters without influencing other properties significantly.
基金supported by the National Natural Science Foundation of China(Grant Nos.11874270 and 12174228)the Shenzhen Basic Research Special Project(Grant No.JCYJ20240813141606009)。
文摘A theory based on the superposition principle is developed to uncover the basic physics of wave behavior in a finite grating of N unit cells.The theory reveals that bound states in the continuum(BICs)of infinite quality factor(Q-factor)can be supported by such a grating when perfect reflection is introduced at its boundaries.If geometrical perturbations are introduced into the structure,the dark BICs transform into bright quasi-BICs with finite Q-factor,maintaining spectral characteristics nearly identical to those of quasi-BICs supported by infinite gratings.When the boundaries are replaced with high-reflectivity metallic mirrors,the Q-factor of the resonant mode is reduced to be finite;however,it can be much larger than that in the corresponding nanostructure with open boundaries and can be tuned over a large range by varying the number of unit cells or boundary conditions.
基金supported by TANAKA KIKINZOKU KOGYO K.Kfinancially supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.NRF-2022R1A2C2006764)the Materials and Components Technology Development Program of MOTIE/KEIT(No.[20012460])。
文摘Ruthenium(Ru)-based chalcogenide(S,Se)is a promising material in various fields,such as optics,photoelectrodes,and electrocatalysis,owing to its suitable bandgap for generating charge carriers under light illumination ranging from visible to near-infrared(NIR)and its high absorption coefficient.In this study,we report the synthesis of Ru Se_(2)thin films by chemical vapor deposition(CVD)with a bandgap matching the NIR region at 0.52 e V.Further,we demonstrated Ru S_(2x)Se_(2-2x)alloy films using the post-sulfurization process after CVD Ru Se_(2)with a tunable bandgap from 0.52 to 1.39 e V depending on sulfur composition.Remarkably,Ru S_(2x)Se_(2-2x)alloy film metal–semiconductor–metal(MSM)photodetector sulfurized at 500°C,with a 0.75 e V bandgap,exhibits enhanced broad absorption across NIR spectral ranges,suppressed dark current and high photoresponsivity in NIR wavelengths range even at zero-bias.We believe the bandgaptunable Ru S_(2x)Se_(2-2x)thin film through an efficient deposition method could be suitable for various optoelectronic applications.
基金supported by the National Natural Science Foundation of China(Grant Number 52472322)the Shanghai Sailing Program(Grant Number 21YF1415800)+1 种基金the Open Project of Key Laboratory of Advanced Public Transportation Science(Grant Number 2023-APTS-05)the Shanghai SASAC Enterprise Innovation and Capability Enhancement Project(Grant Number 2022016,2023020).
文摘Once a train stops in a tunnel section and requires emergency evacuation,the large distance between stations and long walking distances in the underground spaces of suburban railway systems pose potential risks to the evacuation process on tunnel platforms,especially in complex environments.This study utilized Virtual Reality(VR)technology to construct a virtual experimental platform for tunnel evacuation in suburban railway systems,simulating different combinations of smoke and obstacle conditions.By requiring participants to wear VR glasses and walk on an omnidirectional treadmill for moving,as well as complete psychological questionnaires,the study reveals the influences of No Guiding(NG)signs,Wall-Guided(WG)signs,and Central axis Guidance(CG)signs on the movement abilities and psychological behaviors of participants contrastively.The results show that either smoke conditions or obstacle positions affect the mental stress of participants,and the guidance sign has a positive effect on reducing the mental stress.There is an inverse relationship between mental stress and movement abilities.WG and CG signs respectively lead participants to walk closer to walls and along the central axis,which is conducive to reducing the variation in participants’behavior characteristics when circumventing obstacles on the wall side or track side under smoke conditions,respectively.Additionally,CG signs reduce the speed fluctuations of participants before circumventing obstacles,improving the stability of the distance from the wall and speed under smoke conditions,compared to NG and WG signs.These findings contribute to understanding the evacuation psychological-behavioral-movement characteristics of pedestrians on evacuation platforms in suburban railway tunnels and provide a basis for improving the safety design of evacuation guidance signs.
基金supported by the National Natural Science Foundation of China(Grant Nos.12474286,22173052,and 12204281).
文摘The forming processes of 4,40-dipyridyl-based single-molecule junctions and mechanically induced conductance switching as well as the side-group effects are systematically investigated by applying the ab initio-based adiabatic geometric optimization method and the one-dimensional transmission combined with three-dimensional correction approximation(OTCTCA)method.The numerical results show that for the 4,40-dipyridyl with a p-conjugated phenyl-phosphoryl or diphenylsilyl side group,the pyridyl vertically anchors on the second atomic layer of the pyramid-shaped Au tip electrode at small inter-electrode distances by laterally pushing the apical Au atom aside,which induces stronger pyridyl-electrode coupling and high-conductance state of the formed junctions.As the inter-electrode distance increases,the pyridyl shifts to the apical Au atom of the tip electrode.This apical Au atom introduces additional scatterings to the tunneling electrons and significantly decreases the conductance of the junctions.Furthermore,for the 4,40-dipyridyl with a phenyl-phosphoryl side group,the probability of manifesting the high-conductance state is decreased due to the oxygen atom reducing the probability of the pyridyl adsorbing on the second layer of Au tip electrode.In contrast,for the 4,40-dipyridyl with a nonconjugated cyclohexyl-phosphoryl side group,the steric hindrance from the bulky cyclohexyl group leads the molecule to preferentially form the O-Au contact,which prevents both the high conductance and mechanically induced conductance switching of the junction.Our results provide a theoretical understanding of the side-group effects on electronic transport properties of single-molecule junctions,offering an alternative explanation for the experimental observations.
基金supported by the Science and Technology Project of State Grid Corporation of China Headquarters under Grant 5500-202416156A-1-1-ZN.
文摘Sine-wave drive and square-wave drive are two common motor control strategies.This study constructs a mathematical model capable of predicting the distribution of electromagnetic force waves in synchronous reluctance motors(SynRMs)under these two drive methods,and comparatively analyzes the vibration phenomena induced by electromagnetic forces under different drive methods.It aims to provide an effective tool for predicting the distribution of electromagnetic force waves in SynRMs,while exploring the influence of drive modes on their vibration characteristics.The study focuses on a 4-pole,36-slot 5.5 kW SynRM.Based on the magnetomotive force(MMF)-permeance method,incorporating the special rotor structure and the characteristics of current harmonics under square-wave drive,an air-gap flux distribution function is established.Meanwhile,Maxwell’s stress tensor method is adopted to analyze how the air-gap flux density relates to electromagnetic excitation force waves.Subsequently,this analysis is applied to forecast the spatiotemporal distribution features of radial electromagnetic force waves.Finite element simulations are conducted to compute the modal and vibration responses of the SynRM,followed by a comparative analysis of the vibration characteristics under the two drive methods.Additionally,a 6-pole,36-slot SynRM is used for additional comparative verification.Ultimately,the effectiveness of the simulation results is verified through experiments.
