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Effect of heat treatment on microstructure and mechanical properties of selective laser-melted PH13-8Mo stainless steel

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Journal of Iron and Steel Research International 2024年第4期31卷 945-955页

作者： yuan Zhang Xiang Liu Chang-jun wang Chang Liu School of Material Science and Engineering Kunming University of Science and TechnologyKunming 650093YunnanChina Central Iron&Steel Research Institute Co. Ltd.Beijing 100081China

PH13-8Mo stainless steel powder with high sphericity and well fluidity was prepared by the plasma rotating electrode *** formed parts with ultra-high purity were manufactured by selective laser *** tensile and impact mechanical properties of the printed parts under three heat treatment regimes were compared to those without heat *** microstructure,grain orientation and phase composition were characterized by electron-backscatter diffraction,X-ray diffraction and transmission electron *** characterization results reveal that the addition of heat treatment makes the grains enlarge,and after different heat treatments,the average grain size from 1.51μm in the printed state increases to 2.78,3.09 and 2.06μm,*** formed parts are mainly composed of martensite and retained ***,the NiAl and M23C precipitates form,which are the major strengthening phases of PH13-8Mo stainless *** optimal heat treatment process is 925℃×1 h water cooling(WC)+0℃×2 h air cooling(AC)+540℃×4 h *** this heat treatment process,PH13-8Mo formed parts have the optimal comprehensive mechanical properties:the tensile strength,yield strength and impact energy KU2 are 1492 MPa,1432 MPa and 63 J,*** strengthening and toughening via heat treatment are mainly attributed to dislocation strengthening,the formation of NiAl and M23Co precipitates and the change of volume fraction of the retained austenite.

关键词： High-strength stainless steel-Selective laser melting-Heat treatment Microstructure Mechanical property

On the Difference Between the Skew-rank of an Oriented Graph and the Rank of Its Underlying Graph

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 129-136页

作者： Jia-min Zhu Bo-jun yuan Yi wang School of Mathematical Sciences Anhui UniversityHefei230601China School of Science Zhejiang University of Science and TechnologyHangzhou310023China

Let G be a simple graph and G~σ be the oriented graph with G as its underlying graph and orientation σ.The rank of the adjacency matrix of G is called the rank of G and is denoted by r(G).The rank of the skew-adjacency matrix of G~σ is called the skew-rank of G~σ and is denoted by sr(G~σ).Let V(G)be the vertex set and E(G) be the edge set of *** cyclomatic number of G,denoted by c(G),is equal to |E(G)|-|V(G)|+ω(G),where ω(G) is the number of the components of *** is proved for any oriented graph G~σ that-2c(G)≤sr(G~σ)-r(G)≤2c(G).In this paper,we prove that there is no oriented graph G~σwith sr(G~σ)-r(G)=2c(G)-1,and in addition,there are infinitely many oriented graphs G~σ with connected underlying graphs such that c(G)=k and sr(G~σ)-r(G)=2c(G)-l for every integers k,l satisfying 0 ≤l≤4k and l≠1.

关键词： cyclomatic number rank skew-rank

Visible light cross-linking and bioactive peptides loaded integrated hydrogel with sequential release to accelerate wound healing complicated by bacterial infection

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Nano Research 2024年第3期17卷 1737-1747页

作者： Guiyan wang Ning yuan jun Zhang Man Qin Suwei Dong Yuguang wang Department of Pediatric Dentistry Peking University School and Hospital of StomatologyBeijing 100081China State Key Laboratory of Natural and Biomimetic Drugs Chemical Biology Centerand School of Pharmaceutical SciencesPeking UniversityBeijing 100191China Department of Prosthodontics Peking University School and Hospital of StomatologyBeijing 100081China

The effective management of bacterial infections that are resistant to multiple drugs remains a substantial clinical *** eradication of drug-resistant bacteria and subsequent promotion of angiogenesis are imperative for the regeneration of the infected ***,a novel and facile peptide containing injectable hydrogel with sustained antibacterial and angiogenic capabilities is *** antibacterial peptide that consists of 11 residues(CM11,WKLFKKILKVL)is loaded onto acrylate-modified gelatin through charge interactions.A vascular endothelial growth factor mimetic peptide KLT(KLTWQELYQLKYKGI)with a GCG(Gly-Cys-Gly)modification at the N-terminal is covalently coupled through a visible light-induced thiol-ene *** this reaction,the acrylate gelatin undergoes cross-linkage within *** on the physical/chemical double crosslinking strategy,the bioactive peptides achieve sustained and sequential *** results show that the hydrogel significantly inhibits methicillin-resistant Staphylococcus aureus(MRSA)growth through the rapid release of CM11 peptides at early stage;it forms obvious growth inhibition zones against pathogenic bacterial ***,cell counting kit-8 assay and scratch test confirm that the CM11/KLT-functionalized hydrogels promote cell proliferation and migration through the later release of KLT *** a mouse skin wound infected with self-luminous MRSA,the CM11/KLT-functionalized hydrogels enhance wound healing,with rapidly bacterial infection reduction,lower expression of inflammatory factors,and neovascularization *** results suggest that the rationally designed,sustained and sequential release CM11/KLT-functionalized hydrogels have huge potential in promoting the healing of multi-drug resistant bacterial infected wounds.

关键词： antimicrobial peptide vascular endothelial growth factor(VEGF)mimetic peptide sequential release visible-light crosslinking hydrogel wound therapy

Double-layer probiotic encapsulation for enhanced bacteriotherapy against inflammatory bowel disease

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Nano Research 2024年第10期17卷 9103-9110页

作者： Yixin wang jun Liu Sichen yuan Yawen You Quanyin Hu Pharmaceutical Sciences Division School of PharmacyUniversity of Wisconsin-MadisonMadisonWI 53705USA Carbone Cancer Center School of Medicine and Public HealthUniversity of Wisconsin-MadisonMadisonWI 53705USA Wisconsin Center for NanoBioSystems School of PharmacyUniversity of Wisconsin-MadisonMadisonWI 53705USA

Inflammatory bowel disease(IBD)is inflammatory intestinal disorders associated with dysregulated gut *** that leverages bacteria as therapeutics has shown tremendous promise in resolving gut dysbiosis and reducing inflammatory mediators to treat *** delivered probiotics,such as Escherichia coli Nissle 1917(EcN),can produce beneficial ingredients,competitively inhibit the proliferation of pathogens,and promote the restoration of gut microbiome ***,environmental stresses(such as gastric acids)in the gastrointestinal(GI)tract pose an enormous challenge to the probiotics following oral administration,leading to decreases in viability and activity of ***,the inferior mucoadhesive capability of probiotics results in low colonization efficacy,further compromising their therapeutic *** probiotics with functional biomaterials may protect them from elimination and prolong their retention in the GI ***,we developed a facile double-layer electrostatic assembly technique to encapsulate EcN bacteria in protective layers of mucoadhesive chitosan(CS)and immunomodulatory hyaluronic acid(HA)to generate *** biomaterials confer the coated EcN resistance to environmental assault and enhanced mucoadhesion in the GI *** probiotics equipped with the multifunctional shield can thus suppress inflammation and reshape the intestinal microenvironment to enhance therapeutic efficacy for the prevention and treatment of ***,this study presents a novel probiotic coating strategy to augment the outcome of bacteriotherapy to combat IBD.

关键词： probiotics biomaterial coating inflammatory bowel disease mucoadhesion oral administration

Bioinformatic Analysis of Structural Proteins of Paramyxovirus Tianjin Strain

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Virologica Sinica 2008年第4期23卷 279-286页

作者： Li-ying SHI Mei LI Xiao-mian LI Li-jun yuan Qing wang Department of Microbiology the College of Basic Medical Science Tianjin Medical University Tianjin 300070 China

The amino acid sequences of the NP, P, M, F, HN and L proteins of the paramyxovirus Tianjin strain were analyzed by using the bioinformatics methods. Phylogenetic analysis based on 6 structural proteins among the Tianjin strain and 25 paramyxoviruses showed that the Tianjin strain belonged to the genus Respirovirus, in the subfamily Paramyxovirinae, and was most closely related to Sendai virus (SeV). Phylogenetic analysis with 14 known SeVs showed that Tianjin strain represented a new evolutionary lineage. Similarities comparisons indicated that Tianjin strain P protein was poorly conserved, sharing only 78.7% - 91.9% amino acid identity with the known SeVs, while the L protein was the most conserved, having 96.0% - 98.0% amino acid identity with the known SeVs. Alignments of amino acid sequences of 6 structural proteins clearly showed that Tianjin strain possessed many unique amino acid substitutions in their protein sequences, 15 in NP, 29 in P, 6 in M, 13 in F, 18 in HN, and 29 in L. These results revealed that Tianjin strain was most likely a new genotype of SeV. The presence of unique amino acid substitutions suggests that Tianjin strain maybe has a significant difference in biological, pathological, immunological, or epidemiological characteristics from the known SeVs.

关键词： Sendai virus Structural proteins Bioinformatic analysis

Cycloaddition Reactions of Epoxides and CO_(2)Catalyzed by Bifunctional Rare-Earth Metal Complexes Bearing Amino-Bridged Tris(phenolato)Ligands

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Chinese Journal of Chemistry 2024年第14期42卷 1571-1581页

作者： Yongjie Chen Yanwei wang jun Nong Dan yuan Yingming Yao Key Laboratory of Organic Synthesis of Jiangsu Province College of ChemistryChemical Engineering and Materials ScienceDushu Lake CampusSoochow UniversitySuzhouJiangsu215123 China

Eight zwitterionic rare earth metal complexes stabilized by amino-bridged tris(phenolato)ligands bearing quaternary ammonium side-arms were synthesized and *** complexes were used as single-component catalysts for the cycloaddition of CO_(2)and epoxides,and their catalytic activities are obviously higher than those of their binary *** studies revealed that the halide anions(Cl^(–),Br^(–),I^(–))and the metal complexes influenced the catalytic activity,and the lanthanum complex bearing iodide anion showed the highest catalytic activity for this addition reaction.A variety of mono-substituted epoxides were converted to cyclic carbonates in good to excellent yields(55%—99%)with high selectivity(>99%)at 30℃and 1 bar CO_(2),whereas internal epoxides required higher both reaction temperatures(60—120℃)and catalyst loading(2 mol%)for high *** catalyst was recyclable for four times without noticeable loss of catalytic *** on the results of kinetic studies and in℃situ IR reactions,a plausible reaction mechanism was proposed.

关键词： Bifunctional catalyst Carbon dioxide Cyclic carbonate Rare-earth metal Tris(phenolato)ligand Insertion Cycloaddition C1 building blocks

Hypersonic flow control of shock wave/turbulent boundary layer interactions using magnetohydrodynamic plasma actuators

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2020年第9期21卷 745-760页

作者： Hao JIANG jun LIU Shi-chao LUO jun-yuan wang Wei HUANG Science and Technology on Scramjet Laboratory National University of Defense TechnologyChangsha 410073China

The effect of magnetohydrodynamic(MHD)plasma actuators on the control of hypersonic shock wave/turbulent boundary layer interactions is investigated here using Reynolds-averaged Navier-Stokes calculations with low magnetic Reynolds number approximation.A Mach 5 oblique shock/turbulent boundary layer interaction was adopted as the basic configuration in this numerical study in order to assess the effects of flow control using different combinations of magnetic field and *** show that just the thermal effect of plasma under experimental actuator parameters has no significant impact on the flow field and can therefore be *** the basis of the relative position of control area and separation point,MHD control can be divided into four types and so effects and mechanisms might be *** these,D-type control leads to the largest reduction in separation length using magnetically-accelerated plasma inside an isobaric dead-air region.A novel parameter for predicting the shock wave/turbulent boundary layer interaction control based on Lorentz force acceleration is then proposed and the controllability of MHD plasma actuators under different MHD interaction parameters is *** results of this study will be insightful for the further design of MHD control in hypersonic vehicle inlets.

关键词： Hypersonic Shock wave/turbulent boundary layer interaction Magnetohydrodynamic(MHD) Flow control

Adhesive Contact of Elastic Solids with Self-Affine Fractal Rough Surfaces

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Acta Mechanica Solida Sinica 2024年第2期37卷 265-270页

作者： Xuan-Ming Liang Shi-Wen Chen Si-He wang Zhen-yuan Gong jun Feng Gang-Feng wang Department of Engineering Mechanics SVL and MMMLXi’an Jiaotong UniversityXi’an710049China OPPO Mobile Telecommunications Corporation Ltd. Dongguan523860China

The elastic adhesive contact of self-affine fractal rough surfaces against a rigid flat is simulated using the finite element method. An array of nonlinear springs, of which the force-separation law obeys the Lennard–Jones potential, is introduced to account for the interfacial adhesion. For fractal rough surfaces, the interfacial interaction is generally attractive for large mean gaps, but turns repulsive as the gap continuously shrinks. The interfacial interactions at the turning point corresponding to the spontaneous contact are shown for various surfaces. For relatively smooth surfaces, the probability density distributions of repulsion and attraction are nearly symmetric. However, for rougher surfaces, the simulation results suggest a uniform distribution for attraction but a monotonously decreasing distribution with a long tail for repulsion. The pull-off force rises with increasing ratio of the work of adhesion to the equilibrium distance, whereas decreases for solids with a higher elastic modulus and a larger surface roughness. The current study will be helpful for understanding the adhesion of various types of rough solids.

关键词： Fractal rough surfaces Adhesion Contact mechanics Lennard-Jones potential

Highly Red Emissive Conjugated Homopolymers Based on Double B←N Bridged Bipyridine Unit

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Chinese Journal of Polymer Science 2024年第8期42卷 1029-1037页

作者： Yu-Yue Gao Kai-yuan Zhang Shu-Meng wang Hui Tong jun Liu State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026China

Conjugated homopolymers based on six-member rings,e.g.,polyfluorene,always exhibit blue emission and conjugated homopolymers based on five-member rings,e.g.,polythiophene,can give red emission with low *** this work,we report a series of new conjugated homopolymers based on six-member rings with high-efficiency deep-red *** repeating units of the red light emitting homopolymers are double B←N bridged bipyridine(BNBP)with the boron atoms functionalized with diphenyl,borafluorene,and 2,7-di-tert-butyl-borafluorene groups,*** relationship between the chemical structures and the opto-electronic properties of the monomers and the homopolymers has been systematically *** three polymers emit pure red light(λ_(max)=656 nm)or deep red light(λ_(max)=693 nm)with fluorescence quantum efficiency in solution higher than 60%.The polymers can be used as the emitters in solution-processed organic light-emitting diodes with red emission and decent device *** work indicates a new strategy to design highly efficient light emitting conjugated polymers.

关键词： Conjugated homopolymers Double B←N bridged bipyridine(BNBP) Deep-red emission High fluorescent efficiency