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Dynamic stress concentration in an infinitely long cylindrical cavity due to a point spherical source embedded within a fluid-saturated poroelastic formation of infinite extent

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 139-156页

作者： h.hOSSEINI O.BALILAShAKI Department of Mechanical Engineering Faculty of EngineeringGolestan University

The effects of a harmonically exciting monopole source on an infinitely long cylindrical cavity embedded entirely within a fluid-saturated poroelastic formation of infinite extent are examined theoretically. It is assumed that the source is located outside the cavity at a specified distance from the borehole axis. The magnitudes of the hoop and radial stresses beside the pore pressures exerted on the interface and inside the porous medium surrounding the borehole are calculated and discussed. Biot's poroelastic modeling along with three types of boundary conditions for the cylindrical interface including the ideal fluid, empty borehole, and rigid inclusion with a hard boundary is employed for the analysis. Utilizing a proper translational addition theorem for expressing the incident spherical wave in terms of cylindrical wave expansions, the proposed boundary conditions at the interface are satisfied. Stresses are formulated by means of wave potential functions in a three-dimensional(3D) manner. The effects of the frequency and the radial distance between the source and borehole on the induced stresses are examined for the first cylindrical modes over frequency spectra. Two permeability conditions for the interface and three types of soils for the porous formation are considered throughout the analysis. To give an overall outline of the study, a numerical example is presented. The results clearly indicate that the distance is a key parameter and has considerable effects on the induced stress values. In addition, the interface permeability condition and soil characteristics play an important role in determining the dynamic response of the borehole. Finally,the obtained results are compared with the relevant analyses existing in the literature for some limit cases, and good agreement is achieved.

关键词： Stress concentration

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A functional tacrolimus-releasing nerve wrap for enhancing nerve regeneration following surgical nerve repair

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Neural Regeneration Research 2025年第1期20卷 291-304页

作者： Simeon c.Daeschler Katelyn J.W.So Konstantin Feinberg Marina Manoraj Jenny cheung Jennifer Zhang Kaveh Mirmoeini JPaul Santerre Tessa Gordon Gregory hBorschel SickKids Research Institute Neuroscience and Mental Health ProgramTorontoONCanada Institute of Biomaterials and Biomedical Engineering University of TorontoTorontoONCanada Indiana University School of Medicine IndianapolisINUSA Division of Plastic and Reconstructive Surgery the Hospital for Sick ChildrenTorontoONCanada Translational Biology and Engineering Program Ted Rogers Centre for Heart ResearchInstitute of Biomedical EngineeringFaculty of DentistryUniversity of TorontoTorontoONCanada

Axonal regeneration following surgical nerve repair is slow and often incomplete,resulting in poor functional recovery which sometimes contributes to lifelong ***,there are no FDA-approved therapies available to promote nerve *** accelerates axonal regeneration,but systemic side effects presently outweigh its potential benefits for peripheral nerve *** authors describe herein a biodegradable polyurethane-based drug delivery system for the sustained local release of tacrolimus at the nerve repair site,with suitable properties for scalable production and clinical application,aiming to promote nerve regeneration and functional recovery with minimal systemic drug *** is encapsulated into co-axially electrospun polycarbonate-urethane nanofibers to generate an implantable nerve wrap that releases therapeutic doses of bioactive tacrolimus over 31 *** and drug loading are adjustable for applications in small and large caliber nerves,and the wrap degrades within 120 days into biocompatible *** released from the nerve wrap promotes axon elongation in vitro and accelerates nerve regeneration and functional recovery in preclinical nerve repair models while off-target systemic drug exposure is reduced by 80%compared with systemic *** its surgical suitability and preclinical efficacy and safety,this system may provide a readily translatable approach to support axonal regeneration and recovery in patients undergoing nerve surgery.

关键词： biodegradable local drug delivery nerve injury nerve regeneration nerve wrap tacrolimus

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Molecular evidence and phylogenetic delineation of spotted fever group Rickettsia species in Amblyomma ticks from cattle in Gauteng and Limpopo Provinces,South Africa

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Asian Pacific Journal of Tropical Medicine 2023年第8期16卷 371-378页

作者： Keneilwe Mhlambo benson c Iweriebor Nqobile Mkolo K O Afolabi Larry c Obi Department of Biology and Environmental Sciences School of Science and TechnologySefako Makgatho Health Sciences UniversityGa-RankuwaPretoriaSouth Africa Pathogenic Yeasts Research Group Department of Microbiology and BiochemistryUniversity of the Free StateBloemfontein 9300Free StateSouth Africa School of Science and Technology Sefako Makgatho Health Sciences UniversityGa-RankuwaPretoriaSouth Africa

Objective:To determine the prevalence of tick-borne pathogens with a particular focus on Rickettsia *** ticks collected from cattle in Gauteng and Limpopo Provinces,South ***:A total of 200 ticks were collected from cattle within the Madala livestock,Pretoria,Gauteng Province and in Mankweng Township,Polokwane,Limpopo Province in *** ticks were morphologically identified and processed individually for a total genomic DNA *** primers targetting ompA,ompB,and the 17KDa genes were used for a molecular screening and delineation of Rickettsia from the extracted genetic materials using polymerase chain reaction(PcR)*** amplicons of positive samples were sequenced bidirectionally using the Sanger sequencing *** generated were processed and analysed using appropriate bioinformatics ***:The ticks were morphologically identified as Amblyomma *** profiling of the genomic DNA samples revealed the presence of the Rickettsia pathogen in 42(21%)of the ticks collected from both *** of the genes profiled,14(7%)were positive for 17KDa,42(21%)for ompA and 32(16%)were positive for ompB genes *** nucleotide blast of the sequenced genomes showed high similarity,as high as 100% with other reference Rickettsia(R.)africae in the *** phylogenetic analysis of the sequences further validated them as *** with their characteristic clustering pattern with related reference ***:There is an abundance of *** in Amblyomma ticks collected from cattle in the study *** has serious public health implications as individuals who accidentally get infested with the ticks could acquire ***,adequate precautions in terms of sensitization of farmers about the risk and mass mobilization drive to control the vectors in the areas are highly recommended to safeguard public health.

关键词： Amblyomma ticks Tick-borne pathogen Rickettsia cattle South Africa

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ON ThE MODIFIED NONLINEAR SchRDINGER EQUATION IN ThE SEMIcLASSIcAL LIMIT:SUPERSONIc,SUBSONIc,AND TRANSSONIc BEhAVIOR

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Acta Mathematica Scientia 2011年第6期31卷 2343-2377页

作者： Jeffery c. DiFranco Peter D. Miller benson K. Muite Department of Mathematics Seattle University Department of Mathematics University of Michigan

The purpose of this paper is to present a comparison between the modified nonlinear SchrSdinger （MNLS） equation and the focusing and defocusing variants of the （unmodified） nonlinear SchrSdinger （NLS） equation in the semiclassical limit. We describe aspects of the limiting dynamics and discuss how the nature of the dynamics is evident theoretically through inverse-scattering and noncommutative steepest descent methods. The main message is that, depending on initial data, the MNLS equation can behave either like the defocusing NLS equation, like the focusing NLS equation （in both cases the analogy is asymptotically accurate in the semiclassical limit when the NLS equation is posed with appropriately modified initial data）, or like an interesting mixture of the two. In the latter case, we identify a feature of the dynamics analogous to a sonic line in gas dynamics, a free boundary separating subsonic flow from supersonic flow.

关键词： semiclassical limits dispersionless limits modulational instability focusing,defocusing, and modified nonlinear SchrSdinger equations

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Ultra‑Transparent and Multifunctional IZVO Mesh Electrodes for Next‑Generation Flexible Optoelectronics

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Nano-Micro Letters 2025年第1期17卷 293-309页

作者： Kiran A.Nirmal Tukaram D.Dongale Atul c.Khot chenjie Yao Nahyun Kim Tae Geun Kim School of Electrical Engineering Korea UniversityAnam‑ro 145Seongbuk‑guSeoulRepublic of Korea computational Electronics and Nanoscience Research Laboratory School of Nanoscience and BiotechnologyShivaji UniversityKolhapur 416004India

Mechanically durable transparent electrodes are essential for achieving long-term stability in flexible optoelectronic ***,they are crucial for applications in the fields of energy,display,healthcare,and soft *** meshes represent a promising alternative to traditional,brittle,metal oxide conductors due to their high electrical conductivity,optical transparency,and enhanced mechanical *** this paper,we present a simple method for fabricating an ultra-transparent conducting metal oxide mesh electrode using selfcracking-assisted *** this method,we produced an electrode with ultra-transparency(97.39%),high conductance(Rs=21.24Ωsq^(−1)),elevated work function(5.16 eV),and good mechanical *** also evaluated the effectiveness of the fabricated electrodes by integrating them into organic photovoltaics,organic light-emitting diodes,and flexible transparent memristor devices for neuromorphic computing,resulting in exceptional device *** addition,the unique porous structure of the vanadium-doped indium zinc oxide mesh electrodes provided excellent flexibility,rendering them a promising option for application in flexible optoelectronics.

关键词： Self-cracking template Vanadium-doped indium zinc oxide mesh Organic solar cells Organic light-emitting diodes Flexible transparent memory

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Graph neural network modeling of grain-scale anisotropic elastic behavior using simulated and measured microscale data

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npj computational Materials 2022年第1期8卷 2471-2482页

作者： Darren c.Pagan calvin R.Pash Austin R.benson Matthew P.Kasemer Pennsylvania State University University ParkPA16802USA cornell University IthacaNY14853USA University of Alabama TuscaloosaAL35487USA

here we assess the applicability of graph neural networks(GNNs)for predicting the grain-scale elastic response of polycrystalline metallic *** GNN surrogate models,grain-averaged stresses during uniaxial elastic tension in low solvus high-refractory(LShR)Ni Superalloy and Ti 7 wt%Al(Ti-7Al)are predicted as example face-centered cubic and hexagonal closed packed alloys,respectively.A transfer learning approach is taken in which GNN surrogate models are trained using crystal elasticity finite element method(cEFEM)simulations and then the trained surrogate models are used to predict the mechanical response of microstructures measured using high-energy X-ray diffraction microscopy(hEDM).The performance of using various microstructural and micromechanical descriptors for input nodal features to the GNNs is explored through comparisons to traditional mean-field theory predictions,reserved full-field cEFEM data,and measured far-field hEDM *** effects of elastic anisotropy on GNN model performance and outlooks for the extension of the framework are discussed.

关键词： grain neural behavior

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Machine learning empowers efficient design of ternary organic solar cells with PM6 donor

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Journal of Energy chemistry 2025年第1期100卷 337-347页

作者： Kiran A.Nirmal Tukaram D.Dongale Santosh S.Sutar Atul c.Khot Tae Geun Kim School of Electrical Engineering Korea University computational Electronics and Nanoscience Research Laboratory School of Nanoscience and Biotechnology Shivaji University Yashwantrao chavan School of Rural Development Shivaji University

Organic solar cells(OScs) hold great potential as a photovoltaic technology for practical ***, the traditional experimental trial-and-error method for designing and engineering OScs can be complex, expensive, and time-consuming. Machine learning(ML) techniques enable the proficient extraction of information from datasets, allowing the development of realistic models that are capable of predicting the efficacy of materials with commendable accuracy. The PM6 donor has great potential for high-performance OScs. however, it is crucial for the rational design of a ternary blend to accurately forecast the power conversion efficiency(PcE) of ternary OScs(TOScs) based on a PM6 ***, we collected the device parameters of PM6-based TOScs and evaluated the feature importance of their molecule descriptors to develop predictive models. In this study, we used five different ML algorithms for analysis and prediction. For the analysis, the classification and regression tree provided different rules, heuristics, and patterns from the heterogeneous dataset. The random forest algorithm outperforms other prediction ML algorithms in predicting the output performance of PM6-based TOScs. Finally, we validated the ML outcomes by fabricating PM6-based TOScs. Our study presents a rapid strategy for assessing a high PcE while elucidating the substantial influence of diverse descriptors.

关键词： Random forests

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Geometrically constrained isogeometric parameterizedlevel-set based topology optimization via trimmed elements

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Frontiers of Mechanical Engineering 2016年第4期11卷 328-343页

作者： Yingjun WANG David J. benson School of Mechanical and Automotive Engineering South China University of Technology Guangzhou 510641 China Department ofMechanical Engineering McGill University Montreal H3AOC3 Canada Department of Structural Engineering University of California SanDiego 92093 USA

In this paper, an approach based on the fast point-in-polygon (PIP) algorithm and trimmed elements is proposed for isogeometric topology optimization (TO) with arbitrary geometric constraints. The isogeometric parameterized level-set-based TO method, which directly uses the non-uniform rational basis splines (NURBS) for both level set function (LSF) parameterization and objective function calculation, provides higher accuracy and efficiency than previous methods. The integration of trimmed elements is completed by the efficient quadrature rule that can design the quadrature points and weights for arbitrary geometric shape. Numerical examples demonstrate the efficiency and flexibility of the method.

关键词： isogeometric analysis topology optimization level set method arbitrary geometric constraint trimmed element

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Formation of TiN Grid on NiTi by Laser Gas Nitriding for Improving Wear Resistance in hanks' Solution

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Journal of Materials Science & Technology 2016年第5期32卷 459-464页

作者： c.h.Ng O.K.chan h.c.Man Department of Industrial and Systems Engineering The Hong Kong Polytechnic University

Laser gas nitriding （LGN） is a common surface modification method to enhance the wear resistance of titanium （Ti） alloys, which are known to have poor tribological properties. In the present study, a titanium nitride （TIN） grid network was fabricated on the surface of nickel titanium （NiTi） by LGN. The laser processing parameters were selected to achieve nitriding without surface melting and hence to＇maintain a smooth surface finish. The characteristics of the grid-nitrided samples were investigated by scanningelectron microscopy, X-ray diffractometry, optical microscopy, 2-D profilometry, contact angle measurements and nanoindentation. The wear resistance of the nitrided samples was evaluated using reciprocating wear test against ultra-high-molecular-weight polyethylene （UhMWPE） in hanks＇ solution. The results indicate that the wear rates of the grid-nitrided samples and the UhMWPE counter-body in the wear pair are both significantly reduced. The decrease in wear rates can be attributed to the combination of a hard TiN grid and a soft NiTi substrate. In hanks＇ solution, the higher hydrophilicity of the nitrided samples also contributes to the better performance in wear test against hydrophobic UhMWPE.

关键词： Laser Nitriding Surface patterning Titanium alloys Wear

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Numerical simulation and experimental study for rheo-forged component using direct and indirect die system

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Transactions of Nonferrous Metals Society of china 2010年第9期20卷 1799-1804页

作者： h.h.KIM c.G.KANG Precision Manufacturing Systems Division Pusan National University School of Mechanical Engineering Pusan National University

Sand casting and die casting processes have been used widely for complex automotive products such as knuckle, arm, ***, a part fabricated by casting has limited strength due to manufacturing defects such as the dendrite structure, segregation and *** an attempt to offer a solution to these problems, forging has been used as an alternative ***, the forging process provides limited formability for complex shape ***-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming *** order to produce semi-solid materials of the desired microstructure, a stirring process is applied during solidification of molten *** results of an A356 aluminum alloy sample, which are obtained by experiment and by simulation using DEFORM 3D, are present.

关键词： rheo-forging A356 alloy formability forming defects

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