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A laboratory modification to testicular sperm preparation technique improves spermatogenic cell yield

Asian Journal of Andrology 2014年第6期16卷 852-857页

作者： sinan ozkavukcu Ebru Ibis Sule Kizil Suheyla Isbacar Kaan Aydos Department of Obstetrics and Gynecology Center for Assisted Reproduction Ankara University School of Medicine Ankara 06100 Turkey Department of Histology and Embryology Graduate School of Health Sciences Ankara University Ankara 06110 Turkey Department of Urology Ankara University School of Medicine Ankara 06230 Turkey

Testicular sperm extraction is a common procedure used to find spermatogenic cells in men with nonobstructive azoospermia. The laboratory processing of biopsied testicular tissues needs to be performed meticulously to acquire a high yield of cells. In this study, the effectiveness of mincing the tissues after testicular biopsy was assessed using histological evaluation, as was the possible adverse effect of residual tissue on the migration of spermatogenic cells during density gradient centrifugation. Our results indicate that testicular residual tissue, when laid on the density gradient medium along with the sperm wash, hinders the spermatogenic cells＇ forming a pellet during centrifugation, and therefore impairs the intracytoplasmic sperm injection procedure. Whereas the mean number of recovered cells from the sperm wash medium （SWM） with residual tissue is 39.435 ~ 24.849, it was notably higher （60.189 ~ 28.214 cells） in the SWM without minced tissues. The remaining tissue contained no functional seminiferous tubules or spermatogenic cells in histological sections. In conclusion, the remaining residual tissue after mincing biopsied testicular tissue does not add any functional or cellular contribution to spermatogenic cell retrieval; in fact, it may block the cellular elements in the accompanying cell suspension from migrating through the gradient layers to form a pellet during centrifugation and cause loss of spermatogenic cells.

关键词： assisted reproductive techniques azoospermia gradient density centrifugation sperm yield testicular sperm extraction

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A Methodology to Predict Fatigue Life of Cast Iron:Uniform Material Law for Cast Iron

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Journal of Iron and Steel Research International 2011年第8期18卷 42-45页

作者： sinan Korkmaz Applied Computing and Mechanics Laboratory Swiss Federal Institute of Technology(EPFL)ENAC/IIC/IMAC

Mechanical, physical and manufacturing properties of east iron make it attractive for many fields of application, such as cranks and cylinder holds. As in design of all metals, fatigue life prediction is an intrinsic part of the design process of structural sections that are made of cast iron. A methodology to predict high-cycle fatigue life of cast iron is proposed. Stress amplitude-strain amplitude, strain amplitude-number of loading cycles relationships of cast iron are investigated. Also, fatigue life prediction in terms of Smith, Watson and Topper parameter is carried out using the proposed method. Results indicate that the analytical outcomes of the proposed methodology are in good accordance with the experimental data for the two studied types of cast iron： EN-GJS-400 and EN-GJS-600.

关键词： high-cycle fatigue fatigue behavior fatigue life prediction cast iron

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Research on the natural meshing mechanism and testing analysis of scroll profiles for refrigeration scroll compressor

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Science China(Technological Sciences) 2010年第10期53卷 2783-2791页

作者： sinan H HUSSAIN Mechanical Engineering Department Mosul University

In the design theory of scroll profiles for refrigeration scroll compressor,a mechanism principle of scroll profiles based on the center of natural temporal involutes and meshing region is presented,by which the performance characteristics of the various involutes are studied. Profiles type selection is very important for scroll compressor. Through analyzing the characteristic geometry,natural meshing mechanism is discovered in the study of scrolls. And a novel method for scroll profiles based on natural meshing mechanism is proposed. The result shows that the meshing region angle of odd regular polygon involutes is half of the characteristic-geometry exterior angle,and that of even regular polygon involutes is equal to the exterior angle to the moment. The corresponding meshing region angle is reduced increasingly with the increase of the edge number of characteristic geometry. The performance characteristics of scroll compressor tend towards the best correspondingly. Aiming at the existing problems of profile design for scrolls,we developed a novel methodology to study scroll profile. Originality research was done for the further study of scroll profile. It is the fundamentality factor representing essence character of scroll profiles function itself.

关键词： scroll profiles refrigeration scroll compressor natural mechanism temporal meshing center testing analysis

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Role of End-ring Configuration in Shaping IE4 Induction Motor Performance

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CES Transactions on Electrical Machines and Systems 2024年第3期8卷 245-254页

作者： Tayfun Gundogdu sinan Suli Istanbul Technical University Energy InstituteMaslak/İstanbulTürkiye and GAMAK Electric MotorsDudullu OSB34775Ümraniye/İstanbulTürkiye GAMAK Electric Motors Dudullu OSB34775Ümraniye/İstanbulTürkiye

The performance characteristics,particularly the starting performance of direct line-fed induction motors,which are mainly influenced by the design of the rotor,are crucial considerations for *** is quite a challenging issue for motor manufacturers to enhance the starting performance of existing mass-produced motors with minimal modifications and *** this paper,a simple and cost-effective method to improve the starting performance of a commercial squirrel-cage induction motor(SCIM)is *** influence of geometric parameters of the end-ring on the performance characteristics,including starting(locked rotor)torque,pull-up and break down torque,starting current,rotor electric parameters,current density,power losses,and efficiency have been comprehensively *** has been revealed that among the other end-ring design parameters,the ring thickness has a significant effect on the performance *** optimal end-ring thickness is determined,and its performance characteristics have been compared to those of its initial *** and parametric analyses have been conducted using a 2D time-stepping finite element method(FEM).The FEM results were validated using experimental measurements obtained from an 11 kW SCIM prototype.

关键词： End-ring design Induction motor Starting performance Super premium efficiency Torque-speed curve

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Adhesive behavior and detachment mechanisms of bacterial amyloid nanofibers

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npj Computational Materials 2019年第1期5卷 899-906页

作者： Ao Wang sinan Keten Department of Civil and Environmental Engineering Northwestern UniversityEvanstonIL 60208USA Department of Mechanical Engineering and Environmental Engineering Northwestern UniversityEvanstonIL 60208USA

Amyloid nanofibers,such as curli nanofibers,have proven capable of adhering strongly to abiotic ***,the adhesive performance of individual nanofibers and the dependence of this performance on physical properties remain to be *** carried out coarse-grained molecular dynamics simulations to determine the detachment mechanisms of single amyloid fibers from *** a generic model inspired from the curli nanofiber subunit CsgA,we discover that the amyloid nanofibers can undergo three different peeling processes when pulled at a constant rate normal to the *** phase diagrams built from parametric studies indicate that strong nanofibers with high cohesive energy detach by peeling smoothly away from the substrate while weak fibers break *** intermediate ratios,hinge formation occurs and the work of peeling the nanofiber is twice the adhesive energy due to the additional energy required to bend the nanofiber during *** the geometry of amyloid subunits revealed that the work of peeling decreases for thicker nanofibers,suggesting that the tape-like monomeric structure of amyloids may facilitate better adhesive *** results demonstrate how the dimensions and adhesive and cohesive properties of the amyloid nanofibers can be optimized to resist mechanical peeling.

关键词： fibers mechanisms fiber

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Optical Characterization of Amorphous Hydrogenated Carbon(a-C:H)Thin Films Prepared by Single RF Plasma Method

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Plasma Science and Technology 2015年第6期17卷 488-495页

作者： Dogan MANSUROGLU Kadir GOKSEN sinan BILIKMEN Physics Department Middle East Technical University Physics Department Duzce University

Methane （CH4） plasma was used to produce amorphous hydrogenated carbon （a- C：H） films by a single capacitively coupled radio frequency （RF） powered plasma system. The system consists of two parallel electrodes： the upper electrode is connected to 13.56 MHz RF power and the lower one is connected to the ground. Thin films were deposited on glass slides with different sizes and on silicon wafers. The influence of the plasma species on film characteristics was studied by changing the plasma parameters. The changes of plasma species during the deposition were investigated by optical emission spectroscopy （OES）. The structural and optical properties were analyzed via Fourier transform infrared （FTIR） spectroscopy, X-ray diffraction （XRD） and UV-visible spectroscopy, and the thicknesses of the samples were measured by a profilometer. The sp3/sp2 ratio and the existing H atoms play a significant role in the determination of the chemical properties of thin films in the plasma. The film quality and deposition rate were both increased by raising the power and the flow rate.

关键词： a-C:H thin film plasma deposition methane plasma sp3/sp2 ratio

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High temperature tensile,compression and creep behavior of recycled short carbon fibre reinforced AZ91 magnesium alloy fabricated by a high shearing dispersion technique

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Journal of Magnesium and Alloys 2021年第5期9卷 1773-1787页

作者： sinan Kandemir Sarkis Gavras Hajo Dieringa Department of Mechanical Engineering Izmir Institute of Technology35430UrlaIzmirTurkey Helmholtz-Zentrum Hereon MagIC-Magnesium Innovation CentreMax-Planck-Straße 121502GeesthachtGermany Helmholtz-Zentrum Hereon Institute of Metallic BiomaterialsMax-Planck-Straße 121502GeesthachtGermany Helmholtz-Zentrum Hereon Institute of Materials and Process DesignMax-Planck-Straße 121502GeesthachtGermany

The present study seeks the feasibility of using short carbon fibres recycled from polymer matrix composites as alternative to virgin carbon fibres in the reinforcement of magnesium *** microstructures,high temperature mechanical and creep properties of AZ91 alloy and its composites with various recycled carbon fibre contents(2.5 and 5 wt.%)and lengths(100 and 500μm)were investigated in the temperature range of 25-200℃.The microstructural characterization showed that the high shear dispersion technique provided the cast composites with finer grains and relatively homogenous distribution of *** materials tested displayed different behaviour depending on the type of *** general,while enhancements in the mechanical properties of composites is attributed to the load bearing and grain refinement effects of fibres,the fluctuations in the properties were discussed on the basis of porosity formation,relatively high reinforcement content leading to fibre clustering and interlayer found between the matrix and reinforcement compared to those of AZ91 *** compressive creep tests revealed similar or higher minimum creep rates in the recycled carbon fibre reinforced AZ91 in comparison to the unreinforced AZ91.

关键词： Metal matrix composites Magnesium alloys Recycled carbon fibre High-shear dispersion Microstructure Mechanical properties Creep

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Influence of recycled carbon fiber addition on the microstructure and creep response of extruded AZ91 magnesium alloy

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Journal of Magnesium and Alloys 2023年第7期11卷 2518-2529页

作者： sinan Kandemir Jan Bohlen Hajo Dieringa Department of Mechanical Engineering Izmir Institute of TechnologyGülbahçeUrlaIzmir 35430Türkiye Helmholtz-Zentrum Hereon Institute of Material and Process DesignMax-Planck-Straße 1Geesthacht 21502Germany

In this study,the recycled short carbon fiber(CF)-reinforced magnesium matrix composites were fabricated using a combination of stir casting and hot *** objective was to investigate the impact of CF content(2.5 and 5.0 wt.%)and fiber length(100 and 500μm)on the microstructure,mechanical properties,and creep behavior of AZ91 alloy *** microstructural analysis revealed that the CFs aligned in the extrusion direction resulted in grain and intermetallic refinement within the *** comparison to the unreinforced AZ91 alloy,the composites with 2.5 wt.%CF exhibited an increase in hardness by 16-20%and yield strength by 5-15%,depending on the fiber length,while experiencing a reduction in *** the reinforcement content was increased from 2.5 to 5.0 wt.%,strength values exhibited fluctuations and decline,accompanied by decreased *** divergent outcomes were discussed in relation to fiber length,clustering tendency due to higher reinforcement content,and the presence of interfacial products with micro-cracks at the CF-matrix *** creep tests indicated that CFs did not enhance the creep resistance of extruded AZ91 alloy,suggesting that grain boundary sliding is likely the dominant deformation mechanism during creep.

关键词： Metal matrix composites Magnesium alloys Recycled carbon fiber Extrusion,Microstructure Mechanical properties Creep

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Solid-particle erosion behavior of cast alloys used in the mining industry

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International Journal of Minerals,Metallurgy and Materials 2015年第12期22卷 1283-1292页

作者： S.Hakan Atapek sinan Fidan Metallurgical and Materials Engineering Kocaeli University School of Civil Aviation Kocaeli University

The erosive-wear response of five commercial ferrous-based cast alloys used for crushing was examined in this study. The micro- structures of the alloys were modified to elucidate the effect of microstructural features on wear. Erosion tests were conducted using alumi- num oxide particles （90-125μm） at 70 m/s and a normal impact angle （90°）. The worn surfaces were characterized by scanning electron microscopy and 3D non-contact laser profilometry. It is found that （i） a pearlitic structure exhibiting a greater plastic deformation than both bainitic and martensitic structures shows the greatest resistance to erosive wear at normal impact and （ii） the fracture characteristics of carbide and graphite particles plays an important role in determining the erosion wear behavior of the cast alloy matrices.

关键词： mining tools microstructure solid particle impact erosion characterization

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Understanding the genetic basis of rice heterosis: Advances and prospects

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The Crop Journal 2021年第3期9卷 688-692页

作者： sinan Zhang Xuehui Huang Bin Han Shanghai Key Laboratory of Plant Molecular Sciences College of Life SciencesShanghai Normal UniversityShanghai 200234China National Center for Gene Research CAS Center for Excellencein Molecular Plant SciencesInstitute of Plant Physiology and EcologyShanghai Institutes for Biological SciencesChinese Academy of SciencesShanghai 200233China

Heterosis,which describes the superior vigor and yield of F_1 hybrids with respect to their parents,is observed in many rice hybrid *** exploitation of heterosis is a great leap in the history of rice *** advances in genomics and genetics,high-resolution mapping and functional identification of heterosis-associated loci have been performed in *** we summarize advances in understanding the genetic basis of grain yield heterosis in hybrid rice and provide a vision for the genetic study and breeding application of rice heterosis in the future.

关键词： Hybrid rice Heterosis Genetic basis Breeding

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