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Catalyst-free synthesis and mechanical characterization of TaC nanowires

Science China(Physics,Mechanics & Astronomy) 2021年第5期64卷 43-53页

作者： Shiliang Wang Liang Ma james lee mead Shin-Pon Jui Guodong Li Han Huang School of Physics and Electronics Central South University Changsha 410083China School of Mechanical and Mining Engineering.The University of Queensland Brisbane QLD 4072Australia Deparment of Computing Science University of OldenburgOldenburg D-26129Germany Deparment of Mechanical and Electro-Mechanical Engineering Sun Yat-sen UniversiyKaohsiung 804China Deparment of Medicinal and Applied Chemistry Kaohsiung Medical UniversityKaohsiung 807China State Key Laboratory of Powder Metallurgw Central South UniversityChangsha 410083China

TaC nanowires are expected to be an ideal reinforcing material in ultra-high-temperature ceramics. However, their growth mechanisms and mechanical properties remain unclear, and low-cost large-scale synthesis has not been realised. In this study,bulk synthesis of [100]-oriented TaC nanowires is accomplished by carbothermal synthesis through a direct vapor-solid mechanism. Thermal resonance test results show that the synthesized square TaC nanowires with cross-sectional side-lengths of 65 to 497 nm have a size-independent Young’s modulus of(510.6±12.6) GPa;very close to the corresponding values of their bulk counterparts, but differing considerably from previously published measurements. Molecular dynamics(MD) simulations show that TaC nanowires with side-lengths of above 15 nm have a constant Young’s modulus of 517 GPa, and size effects on the modulus values should only occur at side-lengths below 15 nm. During bending tests, the TaC nanowires fracture into several segments in a brittle mode, and exhibit an increasing fracture strain from 1.88% to 4.28% as their side-length decreases from 489 to 90 nm. Weibull statistics analyses and TEM observations indicate that the failure of the nanowires should be primarily dependent on the number and size of surface defects. MD simulations further reveal that the defect-free TaC nanowires fail brittlely at a theoretical strain up to 5.76%.

关键词： tantalum carbide nanowires carbothermal synthesis vapor-solid mechanism mechanical properties

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Frictional shear stress of ZnO nanowires on natural and pyrolytic graphite substrates

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Friction 2022年第12期10卷 2059-2068页

作者： Lizhen HOU Maofen HOU Tursunay YIBIBULLA james lee mead Sergej FATIKOW Shiliang WANG Han HUANG Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education School of Physics and Electronic ScienceHunan Normal UniversityChangsha 410081China School of Physics and Electronics Central South UniversityChangsha 410083China Division Microrobotics and Control Engineering Department of Computing ScienceUniversity of OldenburgOldenburg D-26129Germany School of Mechanical and Mining Engineering The University of QueenslandBrisbaneQLD 4072Australia

The friction behaviour of ZnO nanowires on natural graphite(NG)and highly oriented pyrolytic graphite(HOPG)substrates was tested in ambient conditions by use of optical microscopy based *** on the step-free and waviness-free NG substrate exhibit a diameter-independent nominal frictional shear stress of 0.48 MPa,and this provides a benchmark for studying how the surface topography of graphite influences nanowire *** on the HOPG substrate present a significant diameter-dependent frictional shear stress,increasing from 0.25 to 2.78 MPa with the decrease of nanowire diameter from 485 to 142 *** waviness of HOPG has a limited effect on the nanowire friction,as a nanowire can fully conform to the *** surface steps on the HOPG can significantly enhance the nanowire friction and lead to a much higher frictional shear stress than that on NG due to mechanical blocking and the presence of a Schwoebel barrier at step *** surface steps,however,can also generate small wedge-shaped gaps between a nanowire and substrate,and thus reduce the nanowire *** the decrease in nanowire diameter,the capacity for the nanowire to better conform to the substrate reduces the length of the wedge-shaped gaps,leading to the observed increase in nanowire *** results have improved our understanding of the unique friction behaviour of *** an improved understanding is expected to benefit the design and operation of nanowire-friction-based devices,including bio-inspired fibrillar adhesives,soft grippers,rotary nanomotors,and triboelectric nanogenerators.

关键词： frictional shear stress nanowires graphite surface step waviness

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The HIF-1α/PLOD2 axis integrates extracellular matrix organization and cell metabolism leading to aberrant musculoskeletal repair

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Bone Research 2024年第2期12卷 289-301页

作者： Heeseog Kang Amy L.Strong Yuxiao Sun Lei Guo Conan Juan Alec C.Bancroft Ji Hae Choi Chase A.Pagani Aysel A.Fernandes Michael Woodard Juhoon lee Sowmya Ramesh Aaron W.james David Hudson Kevin N.Dalby Lin Xu Robert J.Tower Benjamin Levi Center for Organogenesis Regeneration and TraumaDepartment of SurgeryUniversity of Texas SouthwesternDallasTX 75390USA Section of Plastic Surgery Department of SurgeryUniversity of MichiganAnn ArborMI 48109USA Quantitative Biomedical Research Center Peter O’Donnell Jr.School of Public HealthUniversity of Texas SouthwesternDallasTX 75390USA Department of Orthopedics and Sports Medicine University of WashingtonSeattleWA 98195USA Division of Chemical Biology and Medicinal Chemistry College of PharmacyUniversity of Texas at AustinAustinTX 78712USA Department of Pathology Johns Hopkins UniversityBaltimoreMD 21218USA

While hypoxic signaling has been shown to play a role in many cellular processes,its role in metabolism-linked extracellular matrix(ECM)organization and downstream processes of cell fate after musculoskeletal injury remains to be ***(HO)is a debilitating condition where abnormal bone formation occurs within extra-skeletal *** andhypoxia-inducible factor 1α(HIF-1α)activation have been shown to promote ***,the underlying molecular mechanisms bywhich the HIF-1αpathway in mesenchymal progenitor cells(MPCs)contributes to pathologic bone formation remain to ***,we used a proven mouse injury-induced HO model to investigate the role of HIF-1αon aberrant cell ***-cell RNA sequencing(scRNA-seq)and spatial transcriptomics analyses of the HO site,we found that collagen ECM organizationis the most highly up-regulated biological process in *** mesenchymal cell-specific deletion of Hif1α(Hoxa11-CreER^(T2);Hif1a^(fl/fl))significantly mitigated HO in ***-seq analysis of these Hoxa11-CreER^(T2);Hif1a^(fl/fl)mice identified the PLOD2/LOXpathway for collagen cross-linking as downstream of the HIF-1αregulation of ***,our scRNA-seq data and mechanisticstudies further uncovered that glucose metabolism in MPCs is most highly impacted by HIF-1α*** a translational aspect,a pan-LOX inhibitor significantly decreased HO.A newly screened compound revealed that the inhibition of PLOD2 activity in MPCssignificantly decreased osteogenic differentiation and glycolytic *** suggests that the HIF-1α/PLOD2/LOX axis linked tometabolism regulates HO-forming MPC *** results suggest that the HIF-1α/PLOD2/LOX pathway represents a promisingstrategy to mitigate HO formation.

关键词： metabolism skeletal aberrant

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A laterally sensitive colloidal probe for accurately measuring nanoscale adhesion of textured surfaces

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Nano Research 2019年第2期12卷 389-396页

作者： Soren Zimmermann Waldemar Klauser james mead Shiliang Wang Han Huang Sergej Fatikow Department of Computing Science University of Oldenburg Oldenburg D-26129 Germany School of Mechanical and Mining Engineering The University of Queensland Brisbane 4072 Australia School of Physics and Electronics Central South University Changsha 410083 China

Adhesiion assessment of nanoscale contacts is a critical capability for the development of future nanoelectromechanical systems and nanobiotechnology devices. However, experimental approaches to investigate interactions on micro- and nanostructured surfaces have predominantly been restricted to capturing adhesion force in the normal direction. This provides limited information about the multidimensional nature of surface texture and related interaction mechanisms. Here the design, fabrication, and application of a unique atomic force microscope probe is presented that consists of a focused ion beam-milled cantilever decorated with a colloidal particle. The probe is specifically developed for characterizing textured surfaces with lateral force feedback. Pull-off tests that map the adhesive interaction in microscale cavities are performed to exami ne the capability of the probe. Normal and lateral adhesive forces duri ng nano scale contact are accurately obtai ned and the adhesi on en ergy of the con tact interface is thus determi ned. An in-depth un dersta nding of the effects of surface texture and the correlati on of adhesi on and fricti on is dem on strated. The proposed methodology en ables dedicated in vestigatio ns of in terfacial in teracti on on various norvplanar surfaces. It can be used for un dersta nding the complex in terplay of adhesi on, con tact, and fricti on forces at nano scale, which may facilitate significant advances in challenging research areas such as fibrillar adhesion.

关键词： nanoscale adhesion friction atomic force microscope colloidal probe lateral sensitivity

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The onset of surface-enhanced Raman scattering for single-particle detection of submicroplastics

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Journal of Environmental Sciences 2022年第11期34卷 58-64页

作者： Cheng-Hao lee james Kar-Hei Fang Department of Applied Biology and Chemical Technology The Hong Kong Polytechnic UniversityKowloonHong Kong SARChina Institute of Textiles and Clothing The Hong Kong Polytechnic UniversityKowloonHong Kong SARChina Research Institute for Future Food The Hong Kong Polytechnic UniversityKowloonHong Kong SARChina State Key Laboratory of Marine Pollution City University of Hong KongKowloonHong Kong SARChina

Microplastics represent an emerging environmental problem worldwide, raising ecological and food safety concerns. Compared to microplastics, there is growing evidence of an even higher abundance of submicro-and nanoplastics in the environment, but a reliable monitoring method for detecting these smaller-sized plastics is lacking. Herein we presented the application of surface-enhanced Raman scattering(SERS) for this purpose. Particles of polystyrene(PS;600 nm) were used as the probe analyte. Gold nanourchins(Au NU;50 nm),i.e. urchin-shaped nanoparticles with irregular spikes around the core, were used as the SERS-active substrate. The effectiveness of SERS on PS was evaluated at a single-particle level with different numbers of Au NU in order to determine the minimum conditions required for the onset of the SERS effect. Our findings suggest that SERS of a single particle of PS can be induced by as few as 1–5 particles of Au NU, and that the use of excitation wavelength at 785 nm is appropriate to meet the red-shifted surface plasmon resonance of Au NU upon aggregation. These specifications provide additional information for the development of SERS-based tools for detecting plastic particles < 1 μm in food and environmental samples.

关键词： Microplastics Nanoplastics Gold nanourchins SERS Food contamination

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CD8+T cell metabolic flexibility elicited by CD28-ARS2 axisdriven alternative splicing of PKM supports antitumor immunity

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Cellular & Molecular Immunology 2024年第3期21卷 260-274页

作者： G.Aaron Holling Colin A.Chavel Anand P.Sharda Mackenzie M.Lieberman Caitlin M.james Shivana M.Lightman Jason H.Tong Guanxi Qiao Tiffany R.Emmons Thejaswini Giridharan Shengqi Hou Andrew M.Intlekofer Richard M.Higashi Teresa W.M.Fan Andrew N.Lane Kevin H.Eng Brahm H.Segal Elizabeth A.Repasky Kelvin P.lee Scott H.Olejniczak Department of Immunology Roswell Park Comprehensive Cancer CenterBuffaloNY 14263USA Department of Medicine Roswell Park Comprehensive Cancer CenterBuffaloNY 14263USA Human Oncology and Pathogenesis Program Memorial Sloan Kettering Cancer CenterNew YorkNY 10065USA Center for Environmental Systems Biochemistry Department of Toxicology and Cancer Biology and Markey Cancer CenterLexingtonKY 40536USA Department of Cancer Genetics and Genomics Roswell Park Comprehensive Cancer CenterBuffaloNY 14263USA Present address:University of Colorado Boulder BoulderCO 80309USA Present address:Dana Farber Cancer Institute BostonMA 02215USA Present address:Massachusetts Institute of Technology BostonMA 02139USA Present address:Melvin and Bren Simon Comprehensive Cancer Center Indiana University School of MedicineIndianapolisIN 46202USA

Metabolic flexibility has emerged as a critical determinant of CD8+T-cell antitumor activity,yet the mechanisms driving the metabolic flexibility of T cells have not been *** this study,we investigated the influence of the nuclear cap-binding complex(CBC)adaptor protein ARS2 on mature T *** doing so,we discovered a novel signaling axis that endows activated CD8+T cells with flexibility of glucose ***2 upregulation driven by CD28 signaling reinforced splicing factor recruitment to pre-mRNAs and affected approximately one-third of T-cell activation-induced alternative splicing *** these effects,the CD28-ARS2 axis suppressed the expression of the M1 isoform of pyruvate kinase in favor of PKM2,a key determinant of CD8+T-cell glucose utilization,interferon gamma production,and antitumor effector ***,PKM alternative splicing occurred independently of CD28-driven PI3K pathway activation,revealing a novel means by which costimulation reprograms glucose metabolism in CD8+T cells.

关键词： Immunometabolism mRNA splicing CD8 T cells ARS2 PKM2

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The NORE1A/RASSF5 Tumor Suppressor Forms a Complex with GSK-3β to Regulate β-Catenin

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Journal of Biosciences and Medicines 2024年第8期12卷 60-75页

作者： M. lee Schmidt Howard Donninger Geoffrey J. Clark Department Pharmacology and Toxicology University of Louisville Louisville USA US Worldmeds LouisvilleUSA Department of Medicine University of Louisville Louisville USA Experimental Therapeutics Program James Graham Brown Cancer Center University of Louisville Louisville USA

NORE1A (RASSF5) is a tumor suppressor of the RASSF family that is often down-regulated in human tumors. NORE1A has multiple roles in controlling cellular homeostasis, one of them being regulating levels of β-catenin by binding and modulating the ubiquitin ligase substrate recognition factor β-TrCP. β-catenin is a major executor of the Wnt pathway. The ubiquitin SCF-β-TrCP ligase complex acts on a phospho-degron site in β-catenin that can be phosphorylated by GSK-3β. We now show that in addition to binding β-TrCP, NORE1A also promotes the phosphorylation of the β-catenin phospho-degron by complexing with the kinase GSK-3β. Indeed, NORE1A enhances the formation of a GSK-3β/β-TrCP complex. A structural mutant of NORE1A that retains β-TrCP binding but will no longer interact with GSK-3β inhibits the β-catenin degrading action of NORE1A. The GSK-3β interaction with NORE1A plays an important role in the biology of NORE1A as a GSK-3β inhibitor blocks NORE1A induced senescence. Thus, we identify a new role for the tumor suppressor NORE1A: The regulation of GSK-3β. GSK-3β has many other substrates including multiple transcription factors and co-activators such as p53 and the Hippo component TAZ. The work implies that NORE1A may be able to influence all of them via this new kinase scaffolding interaction.

关键词： RAS NORE1A RASSF5 GSK-3β Beta Catenin HIPPO

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Micromorphic theory:a gateway to nano world

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International Journal of Smart and Nano Materials 2010年第2期1卷 115-135页

作者： Xianqiao Wang james D.lee Department of Mechanical and Aerospace Engineering The George Washington UniversityWashingtonDC 20052USA

Micromorphic theory(MMT)envisions a material body as a continuous collection of deformable particles;each possesses finite size and inner *** is considered as the most successful top-down formulation of a two-level continuum model,in which the deformation is expressed as a sum of macroscopic continuous deformation and internal microscopic deformation of the inner *** this work,the kinematics including the objective Eringen tensors is *** laws are derived by requiring the energy equation to be form-invariant under the generalized Galilean *** concept of material force and the balance law of pseudomomentum are generalized for *** axiomatic approach is demonstrated in the formulation of constitutive equations for a generalized micromorphic thermoviscoelastic solid,generalized micromorphic fluid,micromorphic plasticity,and micromorphic electromagnetic-thermoelastic *** of MMT in micro/nanoscale are discussed.

关键词： micromorphic theory Eringen tensors constitutive theory generalized micromorphic solid/fluid electromagnetic-thermoelastic coupling micro/nanomechanics

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CONVEX CONTROLLER DESIGN APPLIED TO AC INDUCTION MOTOR TO SATISFY MULTIPLE SIMULTANEOUS SPECIFICATIONS

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Chinese Journal of Mechanical Engineering 2006年第4期19卷 475-479页

作者： lee Seung-Ju SUN Dong MILLS james K Department of Mechanical and Industrial Engineering University of Toronto Toronto MSS 3G8 Canada Department of Manufacturing Engineering and Engineering Management City University of Hong Kong Hong Kong SAR China

The application of a closed-loop specification oriented feedback control design method, which addresses the design of controllers to satisfy multiple simultaneous conflicting closed-loop performance specifications is presented. The proposed approach is well suited to the design of controllers which must meet a set of conflicting performance specifications. Gain tuning is central to the design process, however, the tuning process is greatly simplified over that presented by the problem of tuning a PID controller for example. The proposed control method is applied to an AC induction motor, with an inner-loop flux vector controller applied to design a position control system. Experimental results verify the effectiveness of this method.

关键词： Convex controller design Multiple simultaneous specifications AC induction motor Nonlinear control

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Porous ternary complex metal oxide nanoparticles converted from core/shell nanoparticles

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Nano Research 2016年第4期9卷 996-1004页

作者： Jaewon lee Huazhang Zhu Gautam Ganapati Yadav james Caruthers Yue Wu School of Chemical and Environmental Engineering Shanghai Institute of Technology Shanghai200235 China School of Chemical Engineering Purdue University 480 Stadium Mall Drive West Lafayette IN 47907 USA Department of Chemical and Biological Engineering Iowa State University Sweeney Hall Ames IA 50011 USA Present address: Energy Institute City College of New York New York NY 10031 USA

We demonstrate an easy and scalable low-temperature process to convert porous ternary complex metal oxide nanoparticles from solution-synthesized core^shell metal oxide nanopartides by thermal annealing. The final products demonstrate superior electrochemical properties with a large capacity and high stability during fast charging/discharging cycles for potential applications as advanced lithium-ion battery （LIB） electrode materials. In addition, a new breakdown mechanism was observed on these novel electrode materials.

关键词： ternary complex metal oxide porous nanopartide lithium-ion battery core/shell nanoparticles

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