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Boron-modified perhydropolysilazane towards facile synthesis of amorphous SiBN ceramic with excellent thermal stability

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Journal of Advanced Ceramics 2022年第7期11卷 1104-1116页

作者： Ying ZHAN Wei LI Tianshu JIANG Claudia FASEL emmanuel iii ricohermoso Jan BERNAUER Zhaoju YU Zhenghao WU Florian MÜLLER-PLATHE Leopoldo MOLINA-LUNA Ralf GROTTENMÜLLER Ralf RIEDEL Department of Materials and Earth Sciences Technical University of DarmstadtD-64287 DarmstadtGermany College of Materials Key Laboratory of High Performance Ceramic Fibers(Xiamen University)Ministry of EducationXiamen 361005China Eduard-Zintl-Institut für Anorganische und Physikalische Chemie Technical University of DarmstadtD-64287 DarmstadtGermany Merck KGaA Performance MaterialsD-64293DarmstadtGermany

SiBN ceramics are widely considered to be the most promising material for microwavetransparent applications in harsh environments owing to its excellent thermal stability and low dielectric *** work focuses on the synthesis and ceramization of single-source precursors for the preparation of SiBN ceramics as well as the investigation of the corresponding microstructural evolution at high temperatures including molecular dynamic ***-and chlorine-free perhydropolysilazanes were reacted with borane dimethyl sulfide complex at different molar ratios to synthesize single-source precursors,which were subsequently pyrolyzed and annealed under N2 atmosphere(without ammonolysis)to prepare SiBN ceramics at 1100,1200,and 1300℃with high ceramic yield in contrast to previously widely-used ammonolysis synthesis *** obtained amorphous SiBN ceramics were shown to have remarkably improved thermal stability and oxidation resistance compared to amorphous silicon ***,the experimental results have been combined with molecular dynamics simulation to further study the amorphous structure of SiBN and the atomic-scale diffusion behavior of Si,B,and N at 1300℃.Incorporation of boron into the Si–N network is found to suppress the crystallization of the formed amorphous silicon nitride and hence improves its thermal stability in N2 atmosphere.

关键词： polymer-derived ceramics(PDCs) SiBN crystallization molecular dynamics oxidation resistanc

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Hard and tough novel high-pressure γ-Si_(3)N_(4)/Hf_(3)N_(4) ceramic nanocomposites

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Journal of Advanced Ceramics 2023年第7期12卷 1418-1429页

作者： Wei Li Zhaoju Yu Leonore Wiehl Tianshu Jiang Ying Zhan emmanuel iii ricohermoso Martin Etter Emanuel Ionescu Qingbo Wen Christian Lathe Robert Farla Dharma Teppala Teja Sebastian Bruns Marc Widenmeyer Anke Weidenkaff Leopoldo Molina-Luna Ralf Riedel Shrikant Bhat Department of Materials and Earth Sciences Technical University of DarmstadtDarmstadt 64283Germany Key Laboratory of High Performance Ceramic Fibers(Xiamen University) Ministry of EducationCollege of MaterialsXiamen UniversityXiamen 361005China Deutsches Elektronen-Synchrotron DESY Hamburg 22607Germany Fraunhofer IWKS Department Digitalization of ResourcesAlzenau 63755Germany State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Deutsches GeoForschungsZentrum Potsdam Potsdam 14473Germany

Cubic silicon nitride(-Si_(3)N_(4))is superhard and one of the hardest materials after diamond and cubic boron nitride(cBN),but has higher thermal stability in an oxidizing environment than diamond,making it a competitive candidate for technological applications in harsh conditions(e.g.,drill head and abrasives).Here,we report the high-pressure synthesis and characterization of the structural and mechanical properties of a γ-Si_(3)N_(4)/Hf_(3)N_(4) ceramic nanocomposite derived from single-phase amorphous silicon(Si)-hafnium(Hf)-nitrogen(N)*** synthesis of the-Si_(3)N_(4)/Hf_(3)N_(4) nanocomposite is performed at~20 GPa and ca.1500 ℃ in a large volume multi anvil *** structural evolution of the amorphous precursor and its crystallization to-Si_(3)N_(4)/Hf_(3)N_(4) nanocomposites under high pressures is assessed by the in situ synchrotron energy-dispersive X-ray diffraction(ED-XRD)measurements at~19.5 GPa in the temperature range of ca.1000-1900℃.The fracture toughness(K_(IC))of the two-phase nanocomposite amounts~6/6.9 MPa·m^(1/2) and is about 2 times that of single-phaseγ-Si_(3)N_(4),while its hardness of ca.30 GPa remains *** work provides a reliable and feasible route for the synthesis of advanced hard and tough-Si_(3)N_(4)-based nanocomposites with excellent thermal stabililty.

关键词： cubic silicon nitride(γ-Si_(3)N_(4))/Hf_(3)N_(4) ceramic nanocomposites in situ synchrotron radiation mechanical properties thermal stability

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Bolstering integrity in environmental data science and machine learning requires understanding socioecological inequity

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Frontiers of Environmental Science & Engineering 2024年第5期18卷 171-179页

作者： Joe F.Bozeman iii School of Civil and Environmental Engineering Georgia Institute of TechnologyAtlantaGA30332USA School of Public Policy Georgia Institute of TechnologyAtlantaGA30332USA

Socioecological inequity in environmental data science—such as inequities deriving from data-driven approaches and machine learning(ML)—are current issues subject to debate and *** is growing consensus around embedding equity throughout all research and design domains—from inception to administration,while also addressing procedural,distributive,and recognitional ***,practically doing so may seem onerous or daunting to *** current perspective helps to alleviate these types of concerns by providing substantiation for the connection between environmental data science and socioecological inequity,using the Systemic Equity Framework,and provides the foundation for a paradigmatic shift toward normalizing the use of equity-centered approaches in environmental data science and ML *** the integrity of environmental data science and ML is just beginning from an equity-centered tool development and rigorous application *** this end,this perspective also provides relevant future directions and challenges by overviewing some meaningful tools and strategies—such as applying the Wells-Du Bois Protocol,employing fairness metrics,and systematically addressing irreproducibility;emerging needs and proposals—such as addressing data-proxy bias and supporting convergence research;and establishes a ten-step path ***,the work that environmental scientists and engineers do ultimately affect the well-being of us all.

关键词： Equity Bias Machine Learning Data Science Justice Systemic Equity

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Extinction of Light in the Galactic Halo: First Observational Evidence of the Interaction of Light and Dark Matter

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Journal of Modern Physics 2024年第8期15卷 1144-1198页

作者： Charles H. McGruder iii Department of Physics and Astronomy Western Kentucky University Bowling Green USA

We study the distribution of quasars on the celestial sphere according to ground-based SDSS and space-based WISE and Gaia observations. All distributions as a function of galactic latitude, b, exhibit a decrease in quasar frequency well outside the dust in and near the galactic plane. We prove that the observed decrease in quasar frequency at high galactic latitudes is not accompanied by reddening, meaning that it can not be caused by dust. The scattering of light by the circumgalactic gas is negligible because the Thomson scattering cross section is very small. We conclude the observed scattering of light must be caused by dark matter in the galactic halo. We determine the mass and charge of dark matter particles. If the dark matter particle is a fermion its mass, mDMand charge eDM=δe, where e is the elementary charge are: mDM=3.2×10−2eV and δ=3.856×10−5. If however the dark matter particle is spinless then: mDM=0.511eV and δ=2.132×10−4. These values for the charge of a dark matter particle are orders of magnitude higher than the upper limit of the neutrino charge according to laboratory experiments. Consequently, dark matter particles are not charged neutrinos. Since dark matter particles are charged, they must emit and absorb electromagnetic radiation. However, PDM~δ2, or: PDM~1.487×10−9Pe, where Peis the power output of a single electron.

关键词： Milky Way Dark Matter Halo (1049)

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Cosmology without the Cosmological Principle and without Violating the Copernican Principle: Taub-NUT Universe

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Journal of Modern Physics 2024年第8期15卷 1069-1096页

作者： Charles H. McGruder iii Department of Physics and Astronomy Western Kentucky University Bowling Green Kentucky USA

We develop a theory of cosmology, which is not based on the cosmological principle. We achieve this without violating the Copernican principle. It is well known that the gravitational redshift associated with the Schwarzschild solution applied to the distant supernova does not lead to the observed redsift-distance relationship. We show, however, that generalizations of the Schwarzschild metric, the Taub-NUT metrics, do indeed lead to the observed redshift-distance relationship and to the observed time dilation. These universes are not expanding rather the observed cosmological redshift is due to the gravitational redshift associated with these solutions. Time dilation in these stationary universes has the same dependency on redshift that generally has been seen as proof that space is expanding. Our theory resolves the Hubble tension.

关键词： Cosmology General Relativity

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Cosmological Gravitational Redshift, Spectral Shift and Time in the Taub-NUT Universe

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Journal of Modern Physics 2024年第9期15卷 1448-1459页

作者： Charles H. McGruder iii Department of Physics and Astronomy Western Kentucky University Bowling Green Kentucky USA

We demonstrate that: 1) The Taub-NUT universe is finite. 2) The Taub-NUT universe is much larger than the maximum observable distance according to the standard theory of cosmology. 3) At large distances the spectral s... 详细信息

关键词： Cosmology General Relativity

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A 63-Year-Old Male with D-Transposition of the Great Arteries Who Had an Early Form of the Arterial Switch Operation

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Congenital Heart Disease 2024年第1期19卷 65-68页

作者： Michael A.Rebolledo Jane S.Yao Jason N.Johnson Umar S.Boston Benjamin R.Waller iii Division of Pediatric Cardiology Department of PediatricsThe University of Tennessee Health Science CenterThe Heart InstituteLe Bonheur Children’s HospitalMemphisUSA College of Medicine The University of Tennessee Health ScienceMemphisUSA Division of Pediatric Cardiothoracic Surgery Department of SurgeryThe University of Tennessee Health Science CenterHeart InstituteLe Bonheur Children’s HospitalMemphisUSA

We describe a 63-year-old male who appears to have undergone an early form of the arterial switch operation for D-transposition of the great arteries performed in the *** review the clinical and imaging data that support our *** had a diagnostic cardiac catheterization which demonstrated severe pulmonary hypertension responsive to epoprostenol and *** case may represent one example of the experimental surgical work done prior to *** Jatene’s description of theﬁrst successful arterial switch performed in 1975.

关键词： Adult congenital heart disease arterial switch operation great vessel anomaly imaging(all modalities)

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A Multilayer Perceptron Artificial Neural Network Study of Fatal Road Traffic Crashes

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Journal of Data Analysis and Information Processing 2024年第3期12卷 419-431页

作者： Ed Pearson iii Aschalew Kassu Louisa Tembo Oluwatodimu Adegoke Department of Electrical Engineering & Computer Science Alabama A&M University Normal AL USA Department of Mechanical Civil Engineering & Construction Management Alabama A&M University Normal AL USA Department of Mathematics and Computer Science Alabama State University Montgomery AL USA

This paper examines the relationship between fatal road traffic accidents and potential predictors using multilayer perceptron artificial neural network (MLANN) models. The initial analysis employed twelve potential predictors, including traffic volume, prevailing weather conditions, roadway characteristics and features, drivers’ age and gender, and number of lanes. Based on the output of the model and the variables’ importance factors, seven significant variables are identified and used for further analysis to improve the performance of models. The model is optimized by systematically changing the parameters, including the number of hidden layers and the activation function of both the hidden and output layers. The performances of the MLANN models are evaluated using the percentage of the achieved accuracy, R-squared, and Sum of Square Error (SSE) functions.

关键词： Artificial Neural Network Multilayer Perceptron Fatal Crash Traffic Safety

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Current devices,outcomes,and pain management considerations in penile implant surgery:an updated review of the literature

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Asian Journal of Andrology 2024年第4期26卷 335-343页

作者： Nirupama Ancha Maya Eldin Tarah Woodle Sofia Gereta Krishna Hariprasad Imani Butler E Charles Osterberg iii Department of Surgery and Perioperative Care University of Texas at Austin Dell Medical SchoolAustinTX 78712USA Department of Urology Brooke Army Medical CenterSan AntonioTX 78234USA Department of Molecular Biosciences The University of Texas at AustinAustinTX 78712USA.

Penile prosthesis surgery is a definitive treatment for erectile dysfunction(ED).The two categories of penile prosthesis are endorsed by professional guidelines,inflatable penile prosthesis(IPP)and malleable penile prosthesis(MPP).Each modality of penile prosthesis offers distinct advantages and incorporates specific design features,allowing for personalized device selection that aligns with individual needs and *** the overall complication rate of penile implant surgery remains low,surgeons should maintain a high index of suspicion for complications in the perioperative time *** analgesic regimens including nerve blocks and narcotic-free pathways should be administered to manage perioperative ***,the high patient satisfaction after penile prosthesis surgery underscores the success of this ED treatment option.

关键词： erectile dysfunction penile implant penile prosthesis

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Knowledge‐based deep learning system for classifying Alzheimer's disease for multi‐task learning

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CAAI Transactions on Intelligence Technology 2024年第4期9卷 805-820页

作者： Amol Dattatray Dhaygude Gaurav Kumar Ameta Ihtiram Raza Khan Pavitar Parkash Singh Renato R.Maaliw iii Natrayan Lakshmaiya Mohammad Shabaz Muhammad Attique Khan Hany S.Hussein Hammam Alshazly Department of Data Science University of WashingtonSeattleWashingtonUSA Department of Computer Science&Engineering Parul Institute of TechnologyParul UniversityVadodaraGujaratIndia Department of Computer Science Jamia HamdardDelhiIndia Department of Management Lovely Professional UniversityPhagwaraIndia 5 College of Engineering Southern Luzon State UniversityLucbanQuezonPhilippines Department of Mechanical Engineering Saveetha School of EngineeringSIMATSChennaiTamil NaduIndia Model Institute of Engineering and Technology JammuJ&KIndia Department of Computer Science HITEC UniversityTaxilaPakistan Department of Computer Science and Mathematics Lebanese American UniversityBeirutLebanon Electrical Engineering Department College of EngineeringKing Khalid UniversityAbhaSaudi Arabia Electrical Engineering Department Aswan UniversityAswanEgypt Faculty of Computers and Information South Valley UniversityQenaEgypt

Deep learning has recently become a viable approach for classifying Alzheimer's disease(AD)in medical ***,existing models struggle to efficiently extract features from medical images and may squander additional information resources for illness *** address these issues,a deep three‐dimensional convolutional neural network incorporating multi‐task learning and attention mechanisms is *** upgraded primary C3D network is utilised to create rougher low‐level feature *** introduces a new convolution block that focuses on the structural aspects of the magnetORCID:ic resonance imaging image and another block that extracts attention weights unique to certain pixel positions in the feature map and multiplies them with the feature map ***,several fully connected layers are used to achieve multi‐task learning,generating three outputs,including the primary classification *** other two outputs employ backpropagation during training to improve the primary classification *** findings show that the authors’proposed method outperforms current approaches for classifying AD,achieving enhanced classification accuracy and other in-dicators on the Alzheimer's disease Neuroimaging Initiative *** authors demonstrate promise for future disease classification studies.

关键词： classification deep learning

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