检索结果-南通市图书馆

空位有序双钙钛矿A2BX6的弹性和热电性质的第一性原理研究

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

物理化学学报 2024年第1期40卷 46-47页

作者： muhammad faizan 赵国琪张天旭王啸宇贺欣张立军吉林大学材料科学与工程学院长春130012

卤化物钙钛矿在热电应用中表现出了巨大的潜力。准确了解卤化物钙钛矿的热电传输性质对于进一步提高热电设备的应用效率至关重要。本研究采用了Perdew-Burke-Ernzerhof(PBE)和修正的Becke Johnson(mBJ)交换关联泛函探究了卤化物双钙钛矿... 详细信息

卤化物钙钛矿在热电应用中表现出了巨大的潜力。准确了解卤化物钙钛矿的热电传输性质对于进一步提高热电设备的应用效率至关重要。本研究采用了Perdew-Burke-Ernzerhof(PBE)和修正的Becke Johnson(mBJ)交换关联泛函探究了卤化物双钙钛矿Rb_(2)SnI6、Rb_(2)PdI6和Cs_(2)PtI6的弹性和热电性质。通过对这些材料的力学稳定性、有效质量、塞贝克系数、功率因子和热电品质因数的研究,我们发现,这三种化合物都是力学稳定的,并且具有可塑性。这些化合物是窄带隙半导体,具有简并的带边结构,结合低的载流子有效质量使得它们具有热电应用潜力。Cs_(2)PtI6在空穴掺杂在500 K温度下可以达到0.76 mV·K^(−1)的高塞贝克系数。由于高塞贝克系数和最大功率因子,Rb_(2)SnI6、Rb_(2)PdI6和Cs_(2)PtI6在p型掺杂下具有高的热电品质因数,分别为0.91、0.96和0.98。总体而言,我们的研究为卤化物钙钛矿的热电性能提供了新的见解,为这些化合物的实验合成提供了有价值的参考。

关键词：电子结构有效质量 Seebeck系数热电品质因数卤化物双钙钛矿

Rare earth metal based DES assisted the VPO synthesis for n-butane selective oxidation toward maleic anhydride

在线全文

学校读者我要写书评

暂无评论

Green Energy & Environment 2023年第6期8卷 1737-1752页

作者： muhammad faizan Yingwei Li Xingsheng Wang Piao Song Ruirui Zhang Ruixia Liu Beijing Key Laboratory of Ionic Liquids Clean Process CAS Key Laboratory of Green Process and EngineeringState Key Laboratory of Multiphase Complex SystemInstitute of Process Engineering Chinese Academy of SciencesBeijing100190China University of Chinese Academy of Sciences Beijing100049China Zhengzhou Institute of Emerging Industrial Technology Zhengzhou450000China

Deep eutectic solvents(DESs) are now considered a new class of ionic liquid analogs that have been generously used in various fields.Herein, vanadium phosphorus oxide(VPO) catalysts are synthesized in combination with a deep eutectic solvent containing rare earth metal(rE-DES), and their catalytic performance in n-butane selective oxidation to produce maleic anhydride(MA) is evaluated. The rE-DES is produced from the interaction of choline chloride(ChCl) and rare earth metal salts(Cerium, Europium, Lanthanum, and Samarium metal salt)(ChCl:rE = 1:0.5–1:3) under mild conditions. It was found that DESs served as structural modifiers and electronic promoters during VPO synthesis. It regulated the chemical state of the catalyst surface, such as the vanadium valence state, acid-base properties, and ratios of V^(4+)/V^(5+),Lat–O/Sur–O and P/V. Various characterization techniques, such as FT-IR, DSC, XRD, SEM, EDS, TEM, Raman, TGA, NH3-TPD, and XPS,were used to examine its physical and chemical characteristics. These characteristics were correlated with the catalytic performance. The VPO catalyst modified by rE-DES showed a significant enhancement of n-butane conversion and MA selectivity while suppressing the selectivity of CO and CO_(2)as well as the CO/CO_(2)ratio compared to the unpromoted VPO catalyst. Especially for Ce-DES-VPO, it increased the n-butane conversion and MA mass yield up to approximately 11% and 10%, respectively. In addition, we evaluated the catalytic performance under different activation atmospheres.

关键词： earth anhydride vanadium

Progress of vanadium phosphorous oxide catalyst for n-butane selective oxidation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2022年第3期35卷 297-315页

作者： muhammad faizan Yingwei Li Ruirui Zhang Xingsheng Wang Piao Song Ruixia Liu Beijing Key Laboratory of Ionic Liquids Clean Process State Key Laboratory of Multiphase Complex SystemInstitute of Process Engineering Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The utilization of lighter alkanes into useful chemical products is essential for modern chemistry and reducing the CO_(2)emission.Particularly,n-butane has gained special attention across the globe due to the abundant production of maleic anhydride(MA).Vanadium phosphorous oxide(VPO)is the most effective catalyst for selective oxidation of n-butane to MA so far.Interestingly,the VPO complex exists in more or less fifteen different structures,each one having distinct phase composition and exclusive surface morphology and physiochemical properties such as valence state,lattice oxygen,acidity etc.,which relies on precursor preparation method and the activation conditions of catalysts.The catalytic performance of VPO catalyst is improved by adding different promoters or co-catalyst such as various metals dopants,or either introducing template or structural-directing agents.Meanwhile,new preparation strategies such as electrospinning,ball milling,hydrothermal,barothermal,ultrasound,microwave irradiation,calcination,sol-gel method and solvothermal synthesis are also employed for introducing improvement in catalytic performance.Research in above-mentioned different aspects will be ascribed in current review in addition to summarizing overall catalysis activity and final yield.To analyze the performance of the catalytic precursor,the reaction mechanism and reaction kinetics both are discussed in this review to help clarify the key issues such as strong exothermic reaction,phosphorus supplement,water supplement,deactivation,and air/n-butane pretreatment etc.related to the various industrial applications of VPO.

关键词： N-butane selective oxidation Oxidation of light alkanes Vanadium phosphorus oxide(VPO) Maleic anhydride

Exploration of B-site alloying in partially reducing Pb toxicity and regulating thermodynamic stability and electronic properties of halide perovskites

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2023年第3期66卷 130-138页

作者： Xinjiang Wang muhammad faizan Kun Zhou Hongshuai Zou Qiaoling Xu Yuhao Fu Lijun Zhang State Key Laboratory of Superhard Materials College of PhysicsJilin UniversityChangchun 130012China State Key Laboratory of Integrated Optoelectronics Key Laboratory of Automobile Materials of MOECollege of Materials Science and EngineeringJilin UniversityChangchun 130012China College of Physics and Electronic Engineering Center for Computational SciencesSichuan Normal UniversityChengdu 610068China International Center of Computational Method and Software Jilin UniversityChangchun 130012China

Alloying strategies provide a high degree of freedom for reducing lead toxicity,improving thermodynamic stability, tuning the optoelectronic properties of ABX3 halide perovskites by varying the alloying element species and their contents.Given the key role of B-site cations in contributing band edge states and modulating structure factors in halide perovskites,the partial replacement of Pb2+with different B-site metal ions has been proposed.Although several experimental attempts have been made to date,the effect of B-site alloying on the stability and electronic properties of halide perovskites has not been fully explored.Herein,we take cubic CsPbBr3 perovskite as the prototype material and systematically explore the effects of B-site alloying on Pb-containing perovskites.According to the presence or absence of the corresponding perovskite phase,the ten alloying elements investigated are classified into three types(i.e.,Type Ⅰ:Sn Ge,Ca,Sr;Type Ⅱ:Cd,Mg,Mn;Type Ⅲ:Ba,Zn,Cu).Based on the first-principles calculations,we obtain the following conclusions.First,these B-site alloys will exist as disordered solid solutions rather than ordered structures at room temperature throughout the composition space.Second,the alloying of Sn and Ge enhances the thermodynamic stability of the cubic perovskite host,whereas the alloying of the other elements has no remarkable effect on the thermodynamic stability of the cubic perovskite host.Third,the underlying physical mechanism for bandgap tuning can be attributed to the atomic orbital energy mismatch or quantum confinement effect.Fourth,the alloying of different elements demonstrates the diversity in the regulation of crystal structure and electronic properties,indicating potential applications in photovoltaic s and self-trapped exciton-based light-emitting applications.Our work provides theoretical guidance for using alloying strategies to reduce lead toxicity,enhance stability,and optimize the electronic properties of halide perovskites to meet the needs of optoelectronic applica

关键词： lead-based halide perovskites alloying thermodynamic stability first-principles calculations optoelectronic applications

Anisotropic phonon thermal transport in two-dimensional layered materials

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2023年第4期18卷 217-225页

作者： Yuxin Cai muhammad faizan Huimin Mu Yilin Zhang Hongshuai Zou Hong Jian Zhao Yuhao Fu Lijun Zhang State Key Laboratory of Integrated Optoelectronics Key Laboratory of Automobile Materials of MOEInternational Center of Computational Method and SoftwareSchool of Materials Science and EngineeringJilin UniversityChangchun 130012China State Key Laboratory of Superhard Materials International Center of Computational Method and SoftwareCollege of PhysicsJilin UniversityChangchun 130012China

Two-dimensional layered materials(2DLMs)have attracted growing attention in optoelectronic devices due to their intriguing anisotropic physical properties.Different members of 2DLMs exhibit unique anisotropic electrical,optical,and thermal properties,fundamentally related to their crystal structure.Among them,directional heat transfer plays a vital role in the thermal management of electronic devices.Here,we use density functional theory calculations to investigate the thermal transport properties of representative layered materials:β-InSe,γ-InSe,MoS2,and h-BN.We found that the lattice thermal conductivities ofβ-InSe,γ-InSe,MoS_(2),and h-BN display diverse anisotropic behaviors with anisotropy ratios of 10.4,9.4,64.9,and 107.7,respectively.The analysis of the phonon modes further indicates that the phonon group velocity is responsible for the anisotropy of thermal transport.Furthermore,the low lattice thermal conductivity of the layered InSe mainly comes from low phonon group velocity and atomic masses.Our findings provide a fundamental physical understanding of the anisotropic thermal transport in layered materials.We hope this study could inspire the advancement of 2DLMs thermal management applications in next-generation integrated electronic and optoelectronic devices.

关键词： thermal conductivity two-dimensional layered materials firstprinciples calculation Boltzmann transport theory

空位有序双钙钛矿ABX的弹性和热电性质的第一性原理研究(英文)

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

物理化学学报 2023年

作者： muhammad faizan 赵国琪张天旭王啸宇贺欣张立军吉林大学材料科学与工程学院

卤化物钙钛矿在热电应用中表现出了巨大的潜力。准确了解卤化物钙钛矿的热电传输性质对于进一步提高热电设备的应用效率至关重要。本研究采用了Perdew-Burke-Ernzerhof (PBE)和修正的Becke Johnson (mBJ)交换关联泛函探究了卤化物双钙钛... 详细信息

卤化物钙钛矿在热电应用中表现出了巨大的潜力。准确了解卤化物钙钛矿的热电传输性质对于进一步提高热电设备的应用效率至关重要。本研究采用了Perdew-Burke-Ernzerhof (PBE)和修正的Becke Johnson (mBJ)交换关联泛函探究了卤化物双钙钛矿Rb2SnI6、Rb2PdI6和Cs2PtI6的弹性和热电性质。通过对这些材料的力学稳定性、有效质量、塞贝克系数、功率因子和热电品质因数的研究，我们发现，这三种化合物都是力学稳定的，并且具有可塑性。这些化合物是窄带隙半导体，具有简并的带边结构，结合低的载流子有效质量使得它们具有热电应用潜力。Cs2PtI6在空穴掺杂在500 K温度下可以达到0.76 mV·K-1的高塞贝克系数。由于高塞贝克系数和最大功率因子，Rb2SnI6、Rb2PdI6和Cs2PtI6在p型掺杂下具有高的热电品质因数，分别为0.91、0.96和0.98。总体而言，我们的研究为卤化物钙钛矿的热电性能提供了新的见解，为这些化合物的实验合成提供了有价值的参考。

关键词：电子结构有效质量 Seebeck系数热电品质因数卤化物双钙钛矿

CORM-2插层负载蒙脱土（MMT）的制备、表征及一氧化碳缓释研究

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

CORM-2插层负载蒙脱土（MMT）的制备、表征及一氧化碳缓释研究

作者： muhammad faizan 陕西师范大学

学位级别：硕士

近年来,过渡金属叛基配合物类一氧化碳释放分子(Carbon Monoxide Releasing Molecules,CORM)开始广泛应用于一氧化碳治疗应用研究,并成功模拟了内源性一氧化碳的器官保护、心血管扩张、解热抗炎、抗菌抗癌等生理治疗功能,为相关临床应... 详细信息

近年来,过渡金属叛基配合物类一氧化碳释放分子(Carbon Monoxide Releasing Molecules,CORM)开始广泛应用于一氧化碳治疗应用研究,并成功模拟了内源性一氧化碳的器官保护、心血管扩张、解热抗炎、抗菌抗癌等生理治疗功能,为相关临床应用奠定了坚实的理论和实验基础。然而,此类分子释放一氧化碳必然伴随过渡金属残留,其金属毒性严重制约了相关治疗应用发展。蒙脱石具有很高的离子交换容量和独特的膨胀性能,不但能有效地延迟药物缓释、还可有效为靶向药物增溶。本论文利用蒙脱土为载体,过渡金属羰基配合物配位插层,设计合成了一种具有缓释功能和低金属溶出的一氧化碳释放新材料。模拟生理环境下,CO缓释实验表明,蒙脱土的亲水性、溶胀性能、特别是对重金属吸附特性是抑制CORM重金属离子溶出的有效途径,本论文研究为治疗型一氧化碳释放材料设计提供了新思路。论文具体内容包括:首先,综述了一氧化碳分子与过渡金属羰基配合物类一氧化碳释放分子以及相关释放材料的研究进展,较为系统地评述各类缓释系统的设计原理、制备方法以及生物活性;进而,针对以CORM-02为代表的羰基钌类释放体系,发展了 Ru-MMT原位羰基化反应,羰基钌插层MMT的高效合成,成功制备了两例蒙脱土负载壤基钌的一氧化碳释放材料(Product 1和Product 2)。相关红外光谱表征确定,负载后羰基钌存在于MMT上;通过扫描电镜能谱分析,确定此类材料中金属钌含量约5%;透射电镜和扫描电镜分析显示,负载羰基钌的蒙脱土材料保持了层状结构;XRD分析显示,负载羰基钌后,其层间距有明显增大趋势。热重(TG)分析显示,负载后的样品在100-200℃间有明显的失重,对应于层间吸附的溶剂分子、水分子和羰基钌上CO的受热释放。马心肌红蛋白测试发现,该材料在模拟体外生理环境下可水解缓释一氧化碳,CO释放半衰期远高于CORM-2,具有优良环境耐受性和缓释作用。最后,本文总结了目前各类一氧化碳释放前驱体的特点、一氧化碳检测装置、一氧化碳释放动力学、细胞毒性以及器官积累等相关研究,这些为CO治疗研究提供了最新文献支撑。

关键词：蒙脱土钌金属配合物一氧化碳释放材料碳氧血红蛋白(CO-Hb) 肌红蛋白测定抗菌活

An enhanced scheme for mutual authentication for healthcare services

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

Digital Communications and Networks 2022年第2期8卷 150-161页

作者： Salman Shamshad muhammad faizan Ayub Khalid Mahmood Saru Kumari Shehzad Ashraf Chaudhry Chien-Ming Chen Department of Computer Science COMSATS University IslamabadSahiwal Campus57000Pakistan Department of Mathematics Ch.Charan Singh UniversityMeerutUttar Pradesh250004India Department of Computer Engineering Faculty of Engineering and ArchitectureIstanbul Gelisim UniversityIstanbulTurkey College of Computer Science and Engineering Shandong University of Science and TechnologyQingdao266590China Riphah School of Computing&Innovation(RSCI) Riphah International UniversityLahore CampusLahore 55150Pakistan Department of Mathematics University of Padua35131 PaduaItaly

With the advent of state-of-art technologies,the Telecare Medicine Information System(TMIS)now offers fast and convenient healthcare services to patients at their doorsteps.However,this architecture engenders new risks and challenges to patients'and the server's confidentiality,integrity and security.In order to avoid any resource abuse and malicious attack,employing an authentication scheme is widely considered as the most effective approach for the TMIS to verify the legitimacy of patients and the server.Therefore,several authentication protocols have been proposed to this end.Very recently,Chaudhry et al.identified that there are vulnerabilities of impersonation attacks in Islam et al.'s scheme.Therefore,they introduced an improved protocol to mitigate those security flaws.Later,Qiu et al.proved that these schemes are vulnerable to the man-in-the-middle,impersonation and offline password guessing attacks.Thus,they introduced an improved scheme based on the fuzzy verifier techniques,which overcome all the security flaws of Chaudhry et al.'s scheme.However,there are still some security flaws in Qiu et al.'s protocol.In this article,we prove that Qiu et al.'s protocol has an incorrect notion of perfect user anonymity and is vulnerable to user impersonation attacks.Therefore,we introduce an improved protocol for authentication,which reduces all the security flaws of Qiu et al.'s protocol.We also make a comparison of our protocol with related protocols,which shows that our introduced protocol is more secure and efficient than previous protocols.

关键词： Authentication protocol Security protocol Anonymous protocol Impersonation attack TMIS

An Innovative Approach Utilizing Binary-View Transformer for Speech Recognition Task

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2022年第9期72卷 5547-5562页

作者： muhammad Babar Kamal Arfat Ahmad Khan faizan Ahmed Khan Malik muhammad Ali Shahid Chitapong Wechtaisong muhammad Daud Kamal muhammad Junaid Ali Peerapong Uthansakul COMSATS University Islamabad Islamabad Campus45550Pakistan Suranaree University of Technology Nakhon Ratchasima30000Thailand COMSATS University Islamabad Lahore Campus54000Pakistan COMSATS University Islamabad Vehari Campus61100Pakistan National University of Sciences&Technology Islamabad45550Pakistan Virtual University of Pakistan Islamabad Campus45550Pakistan

The deep learning advancements have greatly improved the performance of speech recognition systems,and most recent systems are based on the Recurrent Neural Network(RNN).Overall,the RNN works fine with the small sequence data,but suffers from the gradient vanishing problem in case of large sequence.The transformer networks have neutralized this issue and have shown state-of-the-art results on sequential or speech-related data.Generally,in speech recognition,the input audio is converted into an image using Mel-spectrogram to illustrate frequencies and intensities.The image is classified by the machine learning mechanism to generate a classification transcript.However,the audio frequency in the image has low resolution and causing inaccurate predictions.This paper presents a novel end-to-end binary view transformer-based architecture for speech recognition to cope with the frequency resolution problem.Firstly,the input audio signal is transformed into a 2D image using Mel-spectrogram.Secondly,the modified universal transformers utilize the multi-head attention to derive contextual information and derive different speech-related features.Moreover,a feedforward neural network is also deployed for classification.The proposed system has generated robust results on Google’s speech command dataset with an accuracy of 95.16%and with minimal loss.The binary-view transformer eradicates the eventuality of the over-fitting problem by deploying a multiview mechanism to diversify the input data,and multi-head attention captures multiple contexts from the data’s feature map.

关键词： Convolution neural network multi-head attention multi-view RNN self-attention speech recognition transformer