Defect engineering in transition metal oxides semiconductors(TMOs)is attracting considerable interest due to its potential to enhance conductivity by intentionally introducing defects that modulate the electronic stru...Defect engineering in transition metal oxides semiconductors(TMOs)is attracting considerable interest due to its potential to enhance conductivity by intentionally introducing defects that modulate the electronic structures of the materials.However,achieving a comprehensive understanding of the relationship between micro-structures and electromagnetic wave absorption capabilities remains elusive,posing a substantial challenge to the advancement of TMOs absorbers.The current research describes a process for the deposition of a MoO_(3)layer onto SiC nanowires,achieved via electro-deposition followed by high-temperature calcination.Subsequently,intentional creation of oxygen vacancies within the MoO_(3)layer was carried out,facilitating the precise adjustment of electromagnetic properties to enhance the microwave absorption performance of the material.Remarkably,the SiC@MO-t4 sample exhibited an excellent minimum reflection loss of-50.49 dB at a matching thickness of 1.27 mm.Furthermore,the SiC@MO-t6 sample exhibited an effective absorption bandwidth of 8.72 GHz with a thickness of 2.81 mm,comprehensively covering the entire Ku band.These results not only highlight the pivotal role of defect engineering in the nuanced adjustment of electromagnetic properties but also provide valuable insight for the application of defect engineering methods in broadening the spectrum of electromagnetic wave absor ption effectiveness.SiC@MO-t samples with varying concentrations of oxygen vacancies were prepared through in-situ etching of the SiC@MoO_(3)nanocomposite.The presence of oxygen vacancies plays a crucial role in adjusting the band gap and local electron distribution,which in turn enhances conductivity loss and induced polarization loss capacity.This finding reveals a novel strategy for improving the absorption properties of electromagnetic waves through defect engineering.展开更多
The conversion of acetone derived from biomass to isobutene has attracted extensive attentions.In comparison with Brønsted acidic catalyst,Lewis acidic catalyst could exhibit a better catalytic performance with a...The conversion of acetone derived from biomass to isobutene has attracted extensive attentions.In comparison with Brønsted acidic catalyst,Lewis acidic catalyst could exhibit a better catalytic performance with a higher isobutene selectivity.However,the catalyst stability remains a key problem for the long-running acetone conversion and the reasons for catalyst deactivation are poorly understood up to now.Herein,the deactivation mechanism of Lewis acidic Y/Beta catalyst during the acetone to isobutene conversion was investigated by various characterization techniques,including acetone-temperature-programmed surface reaction,gas chromatography-mass spectrometry,in situ ultraviolet-visible,and ^(13)C cross polarization magic angle spinning nuclear magnetic resonance spectroscopy.A successive aldol condensation and cyclization were observed as the main side-reactions during the acetone conversion at Lewis acidic Y sites.In comparison with the low reaction temperature,a rapid formation and accumulation of the larger cyclic unsaturated aldehydes/ketones and aromatics could be observed,and which could strongly adsorb on the Lewis acidic sites,and thus cause the catalyst deactivation eventually.After a simple calcination,the coke deposits could be easily removed and the catalytic activity could be well restored.展开更多
Despite the pressing demand for integrated spectrometers,a solution that deliver high-performance while being practically operated is still missing.Furthermore,current integrated spectrometers lack reconfigurability i...Despite the pressing demand for integrated spectrometers,a solution that deliver high-performance while being practically operated is still missing.Furthermore,current integrated spectrometers lack reconfigurability in their performance,which is highly desirable for dynamic working scenarios.This study presents a viable solution by demonstrating a userfriendly,reconfigurable spectrometer on silicon.At the core of this innovative spectrometer is a programmable photonic circuit capable of exhibiting diverse spectral responses,which can be significantly adjusted using on-chip phase shifters.The distinguishing feature of our spectrometer lies in its inverse design approach,facilitating effortless control and efficient manipulation of the programmable circuit.By eliminating the need for intricate configuration,our design reduces power consumption and mitigates control complexity.Additionally,our reconfigurable spectrometer offers two distinct operating conditions.In the Ultra-High-Performance mode,it is activated by multiple phase-shifters and achieves exceptional spectral resolution in the picometer scale while maintaining broad bandwidth.On the other hand,the Ease-of-Use mode further simplifies the control logic and reduces power consumption by actuating a single-phase shifter.Although this mode provides a slightly degraded spectral resolution of approximately 0.3 nm,it prioritizes ease of use and is wellsuited for applications where ultra-fine spectral reconstruction is not a primary requirement.展开更多
In this paper, we mainly study the orbital graphs of primitive groups with the socle A<sub>7</sub> x A<sub>7 </sub>which acts by diagonal action. Firstly, we calculate the element conjugat...In this paper, we mainly study the orbital graphs of primitive groups with the socle A<sub>7</sub> x A<sub>7 </sub>which acts by diagonal action. Firstly, we calculate the element conjugate classes of A7</sub>, then we discuss the stabilizer of two points in A7</sub>. Finally, according to the relation between suborbit and orbital, we obtain the orbitals, and determine the orbital graphs.展开更多
It is essential to utilize deep-learning algorithms based on big data for the implementation of the new generation of artificial intelligence. Effective utilization of deep learning relies considerably on the number o...It is essential to utilize deep-learning algorithms based on big data for the implementation of the new generation of artificial intelligence. Effective utilization of deep learning relies considerably on the number of labeled samples, which restricts the application of deep learning in an environment with a small sample size. In this paper, we propose an approach based on a generative adversarial network (GAN) combined with a deep neural network (DNN). First, the original samples were divided into a training set and a test set. The GAN was trained with the training set to generate synthetic sample data, which enlarged the training set. Next, the DNN classifier was trained with the synthetic samples. Finally, the classifier was tested with the test set, and the effectiveness of the approach for multi-classification with a small sample size was validated by the indicators. As an empirical case, the approach was then applied to identify the stages of cancers with a small labeled sample size. The experimental results verified that the proposed approach achieved a greater accuracy than traditional methods. This research was an attempt to transform the classical statistical machine-learning classification method based on original samples into a deep-learning classification method based on data augmentation. The use of this approach will contribute to an expansion of application scenarios for the new generation of artificial intelligence based on deep learning, and to an increase in application effectiveness. This research is also expected to contribute to the comprehensive promotion of new-generation artificial intelligence.展开更多
The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunction...The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunctional TiSn‐Beta zeolite was prepared by a simple and scalable post‐synthesis approach,and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2‐diols.The isolated Ti and Sn Lewis acid sites within the TiSn‐Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one‐step conversion of alkenes to 1,2‐diols with a high selectivity of>90%.Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product.Further,the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production.展开更多
Green and economical CO_(2)utilization is significant for CO_(2)emission reduction and energy development.Here,the 1D Mo_(2)C nanowires with dominant(101)crystal surfaces were modified by the deposition of atomic func...Green and economical CO_(2)utilization is significant for CO_(2)emission reduction and energy development.Here,the 1D Mo_(2)C nanowires with dominant(101)crystal surfaces were modified by the deposition of atomic functional components Rh and K.While unmodifiedβMo_(2)C could only convert CO_(2)to methanol,the designed catalyst of K_(0.2)Rh_(0.2)/β-Mo_(2)C exhibited up to 72.1%of ethanol selectivity at 150℃.It was observed that the atomically dispersed Rh could form the bifunctional active centres with the active carrierβMo_(2)C with the synergistic effects to achieve highly specific controlled C–C coupling.By promoting the CO_(2)adsorption and activation,the introduction of an alkali metal(K)mainly regulated the balanced performance of the two active centres,which in turn improved the hydrogenation selectivity.Overall,the controlled modification ofβMo_(2)C provides a new design strategy for the highly efficient,lowtemperature hydrogenation of CO_(2)to ethanol with single-atom catalysts,which provides an excellent example for the rational design of the complex catalysts.展开更多
目的目前美军较为成熟的战伤编码系统为美军战地医疗系统伤情编码(Deployable medical systems patient conditions,PCs)和美军战伤定级编码系统(Military Combat Injury Scale,MCIS)。PCs由于包含战伤诊断、救治概要、生存概率以及后...目的目前美军较为成熟的战伤编码系统为美军战地医疗系统伤情编码(Deployable medical systems patient conditions,PCs)和美军战伤定级编码系统(Military Combat Injury Scale,MCIS)。PCs由于包含战伤诊断、救治概要、生存概率以及后送要求等要素,广泛应用于卫勤领域的模拟仿真系统,但对于真实战伤诊断数据的编码率较低,且无法对严重程度定级。MCIS具有针对强、简单易用等特点,能够较好地对真实战伤诊断进行编码并对战伤严重度定级,但目前仅包括战伤诊断要素,缺少卫勤决策支持的其他要素。因此本文通过对两套编码系统进行对比与转换研究,探究建立两套编码系统转换规则的可行性,从而使得真实战伤数据和模拟仿真数据相结合,共同为卫勤决策提供支持,并为构建我军战伤编码提供建议。方法提取PCs中187个战伤伤情编码,将PCs和MCIS编码指导手册分别交给3名资深编码员,分别将两套编码进行匹配并记录。计算不同编码员匹配记录的加权Kappa系数用以评价评分者间信度。结果两套编码匹配记录的评分者信度较差。结论亟待建立一套既能编码真实战伤诊断数据,又涵盖卫勤决策支持要素的战伤分类与编码系统,从而将真实数据与模拟仿真数据相结合,共同形成决策证据为卫勤保障提供决策支持。展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos. 52072196, 52002200, 52102106, 52202262, 22379081, 22379080Major Basic Research Program of Natural Science Foundation of Shandong Province under Grant No. ZR2020ZD09+1 种基金the Natural Science Foundation of Shandong Province under Grant Nos. ZR2020QE063, ZR2022ME090, ZR2023QE059. Moreoversupported by the Visiting Scholar Fellowship Funding for Teachers in Shandong Province’s General Undergraduate Institutions
文摘Defect engineering in transition metal oxides semiconductors(TMOs)is attracting considerable interest due to its potential to enhance conductivity by intentionally introducing defects that modulate the electronic structures of the materials.However,achieving a comprehensive understanding of the relationship between micro-structures and electromagnetic wave absorption capabilities remains elusive,posing a substantial challenge to the advancement of TMOs absorbers.The current research describes a process for the deposition of a MoO_(3)layer onto SiC nanowires,achieved via electro-deposition followed by high-temperature calcination.Subsequently,intentional creation of oxygen vacancies within the MoO_(3)layer was carried out,facilitating the precise adjustment of electromagnetic properties to enhance the microwave absorption performance of the material.Remarkably,the SiC@MO-t4 sample exhibited an excellent minimum reflection loss of-50.49 dB at a matching thickness of 1.27 mm.Furthermore,the SiC@MO-t6 sample exhibited an effective absorption bandwidth of 8.72 GHz with a thickness of 2.81 mm,comprehensively covering the entire Ku band.These results not only highlight the pivotal role of defect engineering in the nuanced adjustment of electromagnetic properties but also provide valuable insight for the application of defect engineering methods in broadening the spectrum of electromagnetic wave absor ption effectiveness.SiC@MO-t samples with varying concentrations of oxygen vacancies were prepared through in-situ etching of the SiC@MoO_(3)nanocomposite.The presence of oxygen vacancies plays a crucial role in adjusting the band gap and local electron distribution,which in turn enhances conductivity loss and induced polarization loss capacity.This finding reveals a novel strategy for improving the absorption properties of electromagnetic waves through defect engineering.
文摘The conversion of acetone derived from biomass to isobutene has attracted extensive attentions.In comparison with Brønsted acidic catalyst,Lewis acidic catalyst could exhibit a better catalytic performance with a higher isobutene selectivity.However,the catalyst stability remains a key problem for the long-running acetone conversion and the reasons for catalyst deactivation are poorly understood up to now.Herein,the deactivation mechanism of Lewis acidic Y/Beta catalyst during the acetone to isobutene conversion was investigated by various characterization techniques,including acetone-temperature-programmed surface reaction,gas chromatography-mass spectrometry,in situ ultraviolet-visible,and ^(13)C cross polarization magic angle spinning nuclear magnetic resonance spectroscopy.A successive aldol condensation and cyclization were observed as the main side-reactions during the acetone conversion at Lewis acidic Y sites.In comparison with the low reaction temperature,a rapid formation and accumulation of the larger cyclic unsaturated aldehydes/ketones and aromatics could be observed,and which could strongly adsorb on the Lewis acidic sites,and thus cause the catalyst deactivation eventually.After a simple calcination,the coke deposits could be easily removed and the catalytic activity could be well restored.
基金supports from following sources:National Key R&D Program of China(grant No.2021YFB2801500)National Natural Science Foundation of China(grant No.62375126,No.62105149 and No.62334001)+1 种基金Natural Science Foundation of Jiangsu Province(grant No.BK20210288)Opening Foundation of Key Laboratory of Laser&Infrared System(Shandong University),Minister of Education Key Lab of Modern Optical Technologies of Education Ministry of China,Soochow University State Key Laboratory of Advanced Optical Communication Systems and Networks,China Specially-appointed Professor Fund of Jiangsu.
文摘Despite the pressing demand for integrated spectrometers,a solution that deliver high-performance while being practically operated is still missing.Furthermore,current integrated spectrometers lack reconfigurability in their performance,which is highly desirable for dynamic working scenarios.This study presents a viable solution by demonstrating a userfriendly,reconfigurable spectrometer on silicon.At the core of this innovative spectrometer is a programmable photonic circuit capable of exhibiting diverse spectral responses,which can be significantly adjusted using on-chip phase shifters.The distinguishing feature of our spectrometer lies in its inverse design approach,facilitating effortless control and efficient manipulation of the programmable circuit.By eliminating the need for intricate configuration,our design reduces power consumption and mitigates control complexity.Additionally,our reconfigurable spectrometer offers two distinct operating conditions.In the Ultra-High-Performance mode,it is activated by multiple phase-shifters and achieves exceptional spectral resolution in the picometer scale while maintaining broad bandwidth.On the other hand,the Ease-of-Use mode further simplifies the control logic and reduces power consumption by actuating a single-phase shifter.Although this mode provides a slightly degraded spectral resolution of approximately 0.3 nm,it prioritizes ease of use and is wellsuited for applications where ultra-fine spectral reconstruction is not a primary requirement.
文摘In this paper, we mainly study the orbital graphs of primitive groups with the socle A<sub>7</sub> x A<sub>7 </sub>which acts by diagonal action. Firstly, we calculate the element conjugate classes of A7</sub>, then we discuss the stabilizer of two points in A7</sub>. Finally, according to the relation between suborbit and orbital, we obtain the orbitals, and determine the orbital graphs.
基金the National Natural Science Foundation of China (91646102, L1724034, L16240452, L1524015, and 20905027)the MOE (Ministry of Education in China) Project of Humanities and Social Sciences (16JDGC011)+3 种基金the Chinese Academy of Engineering’s China Knowledge Center for Engineering Sciences and Technology Project (CKCEST-2018-1-13)the UK– China Industry Academia Partnership Programme (UK-CIAPP/260)Volvo-Supported Green Economy and Sustainable Development at Tsinghua University (20153000181)the Tsinghua Initiative Research Project (2016THZW).
文摘It is essential to utilize deep-learning algorithms based on big data for the implementation of the new generation of artificial intelligence. Effective utilization of deep learning relies considerably on the number of labeled samples, which restricts the application of deep learning in an environment with a small sample size. In this paper, we propose an approach based on a generative adversarial network (GAN) combined with a deep neural network (DNN). First, the original samples were divided into a training set and a test set. The GAN was trained with the training set to generate synthetic sample data, which enlarged the training set. Next, the DNN classifier was trained with the synthetic samples. Finally, the classifier was tested with the test set, and the effectiveness of the approach for multi-classification with a small sample size was validated by the indicators. As an empirical case, the approach was then applied to identify the stages of cancers with a small labeled sample size. The experimental results verified that the proposed approach achieved a greater accuracy than traditional methods. This research was an attempt to transform the classical statistical machine-learning classification method based on original samples into a deep-learning classification method based on data augmentation. The use of this approach will contribute to an expansion of application scenarios for the new generation of artificial intelligence based on deep learning, and to an increase in application effectiveness. This research is also expected to contribute to the comprehensive promotion of new-generation artificial intelligence.
基金funded by the National Key Research and Development Program of China(No.2021YFB3700801)by the State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China。
文摘The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single‐pass tandem catalytic reaction.In this study,bifunctional TiSn‐Beta zeolite was prepared by a simple and scalable post‐synthesis approach,and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2‐diols.The isolated Ti and Sn Lewis acid sites within the TiSn‐Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one‐step conversion of alkenes to 1,2‐diols with a high selectivity of>90%.Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product.Further,the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production.
基金financially supported by the National Natural Science Foundation of China(21925803,U19A2015)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB36030200)the Liao Ning Revitalization Talents Program(XLYC1907170).
文摘Green and economical CO_(2)utilization is significant for CO_(2)emission reduction and energy development.Here,the 1D Mo_(2)C nanowires with dominant(101)crystal surfaces were modified by the deposition of atomic functional components Rh and K.While unmodifiedβMo_(2)C could only convert CO_(2)to methanol,the designed catalyst of K_(0.2)Rh_(0.2)/β-Mo_(2)C exhibited up to 72.1%of ethanol selectivity at 150℃.It was observed that the atomically dispersed Rh could form the bifunctional active centres with the active carrierβMo_(2)C with the synergistic effects to achieve highly specific controlled C–C coupling.By promoting the CO_(2)adsorption and activation,the introduction of an alkali metal(K)mainly regulated the balanced performance of the two active centres,which in turn improved the hydrogenation selectivity.Overall,the controlled modification ofβMo_(2)C provides a new design strategy for the highly efficient,lowtemperature hydrogenation of CO_(2)to ethanol with single-atom catalysts,which provides an excellent example for the rational design of the complex catalysts.
文摘目的目前美军较为成熟的战伤编码系统为美军战地医疗系统伤情编码(Deployable medical systems patient conditions,PCs)和美军战伤定级编码系统(Military Combat Injury Scale,MCIS)。PCs由于包含战伤诊断、救治概要、生存概率以及后送要求等要素,广泛应用于卫勤领域的模拟仿真系统,但对于真实战伤诊断数据的编码率较低,且无法对严重程度定级。MCIS具有针对强、简单易用等特点,能够较好地对真实战伤诊断进行编码并对战伤严重度定级,但目前仅包括战伤诊断要素,缺少卫勤决策支持的其他要素。因此本文通过对两套编码系统进行对比与转换研究,探究建立两套编码系统转换规则的可行性,从而使得真实战伤数据和模拟仿真数据相结合,共同为卫勤决策提供支持,并为构建我军战伤编码提供建议。方法提取PCs中187个战伤伤情编码,将PCs和MCIS编码指导手册分别交给3名资深编码员,分别将两套编码进行匹配并记录。计算不同编码员匹配记录的加权Kappa系数用以评价评分者间信度。结果两套编码匹配记录的评分者信度较差。结论亟待建立一套既能编码真实战伤诊断数据,又涵盖卫勤决策支持要素的战伤分类与编码系统,从而将真实数据与模拟仿真数据相结合,共同形成决策证据为卫勤保障提供决策支持。
