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Surgical Method for Facilitation of Aortic Valve Replacement:Intraoperative Application of External Pressure for Increasing the Transverse Axis of Aortic Annulus

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World Journal of Cardiovascular Surgery 2015年第10期5卷 108-113页

作者： sahin bozok Mert Kestelli Aykut sahin Hakan Kara Tevfik Günes Berkan Ozpak Gokhan Ilhan Serdar Bayrak Department of Cardiovascular Surgery Recep Tayyip Erdogan University Faculty of MedicineTraining and Research HospitalRizeTurkey Department of Cardiovascular Surgery Izmir Katip Celebi University Faculty of MedicineAtatürk Training and Research HospitalIzmirTurkey Department of Cardiovascular Surgery Osmangazi University Faculty of MedicineEskisehirTurkey Department of Cardiovascular Surgery Ada HospitalGiresunTurkey Department of Cardiovascular Surgery Pamukkale University Faculty of MedicineDenizliTurkey

Background: Surgical method was introduced for enhancement of prosthetic valve insertion and overcoming difficulties ensourcing from prosthesis-patient mismatch. Methods: Twenty-two patients that underwent aortic valve replacement between January 2005 and July 2009 were included in this prospective study. In these patients, the insertion of prosthesis larger than the annulus diameter was attempted after the application of an external pressure that increased the transverse axis diameter of the aortic annulus. The postoperative results and complications were assessed. Results: This surgical method was performed on 22 patients (16 males, 6 females, mean age: 52.2 ± 15.8 years) during the valve replacement. In 12 patients (55%), replacement of proper sized aortic valve compliant to their surface area was accomplished, while the insertion of a proper valve could not be achieved in 10 (45%) of the patients. No perioperative mortality or complications related to the procedure were reported. Conclusion: Increasing the transverse diameter of aortic valve may not only facilitate the insertion of a prosthetic valve but also aid in overcoming prosthesis-patient mismatch. Further studies on larger series are necessary to document the actual effectively and precise selection criteria for application of this method.

关键词： Aortic Valve Replacement Prosthesis Mismatch Aortic Annulus

The evolving landscape of biliary tract cancers:comparing French and US National Comprehensive Cancer Network guidelines

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Hepatobiliary Surgery and Nutrition 2024年第5期13卷 850-853页

作者： Muhammet Ozer Ilyas sahin Department of Medical Oncology Dana Farber Cancer InstituteHarvard Medical SchoolBostonMAUSA Division of Hematology/Oncology Department of MedicineUniversity of FloridaGainesvilleFLUSA University of Florida Health Cancer Center GainesvilleFLUSA

Biliary tract cancers(BTCs)constitute a heterogeneous group of hepatobiliary malignancies originating along the biliary *** up to 20%of primary hepatobiliary tumors consist of BTCs(1).The primary risk factors include cholelithiasis,chronic inflammatory diseases of the bile ducts,non-alcoholic steatohepatitis(NASH),liver cirrhosis,tobacco use,and chronic viral hepatitis B and C infections(2).

关键词： Clinical practice biliary tract cancers(BTCs) French guidelines National Comprehensive Cancer Network guidelines(NCCN guidelines)

Median Nerve Somatosensory Evoked Potentials in Patients with Chiari Malformation

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World Journal of Neuroscience 2024年第1期14卷 24-32页

作者： Mustafa Harun sahin Gonul Vural Serdar Barakli Sadiye Gumusyayla Department of Neurology Ankara City Hospital Ankara Türkiye Department of Neurology Sinop Ataturk State Hospital Sinop Türkiye Department of Neurology Faculty of Medicine Ankara Yildirim Beyazit University Ankara Türkiye Department of Neurology Sungurlu State Hospital Corum Türkiye

Abnormal SEP reflects dysfunction of the medial lemniscus and posterior cervical cord. These structures are likely to be affected in Chiari malformation. Therefore, SEP abnormalities may provide valuable information in patients with CM. However, the consistency of SEP abnormality or normality with the damage is a matter of research. Knowing whether median nerve somatosensory evoked potential (SEP) is useful in revealing subclinical damage in patients with Chiari malformation is important in the treatment and follow-up plan of the disease. The aim of this study was to investigate the relationship between median nerve SEP values and the severity of cerebellar ectopia in patients with Chiari type 1 malformation. Median nerve SEP values were obtained from 30 healthy individuals and 146 individuals with Chiari malformation. The cerebellar ectopia degree and McRae line length were measured. SEP values were not significantly different between groups. The McRae line was found to be significantly shorter in the control group than in the Chiari malformation group (p = 0.031). There was no correlation between the degree of cerebellar ectopia and the length of the McRae line (r = 0.002, p = 0.979). Neither cerebellar ectopy degree nor McRae line length had a relationship with SEP values (r = -0.153, p = 0.066;r = -0.056, p = 0.500, respectively). There was no difference in cerebellar ectopy degree or SEP values between the groups with cerebellar ectopy with and without a syrinx (p = 0.899;p = 0.080, respectively). Likewise, McRae line length was not found to be related to the presence of a syrinx (p = 0.139). Median nerve SEP examination was not beneficial for diagnosing asymptomatic-oligosymptomatic Chiari malformation as a subclinical injury, whether accompanied by syringomyelia or not.

关键词： Chiari Malformation Cerebellar Ectopy Somatosensory Evoked Potential

Indentation Load Effect on Young＇s Modulus and Hardness of Porous Sialon Ceramic by Depth Sensing Indentation Tests

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Chinese Physics Letters 2007年第11期24卷 3206-3209页

作者： Osman sahin Department of Physics Art and Science Faculty Silleyman Demirel University Isparta Turkey

Depth sensing indentation （DSI） tests at the range of 200-1800mN are performed on porous sialon ceramic to determine the indentation load on Young＇s modulus and hardness values. The Young modulus and hardness （Dynamic and Martens） values are deduced by analysing the unloading segments of the DSI test load-displacement curves using the Oliver-Pharr method. It is found that Young＇s modulus ET, the dynamic hardness HD and the Martens hardness HM exhibit significant indentation load dependences. The values of Young＇s modulus and hardness decrease with the increasing indentation load, as a result of indentation load effect. The experimental hf /hm ratios lower than the critical value 0.7, with hm being the maximum penetration depth during loading and hf the final unloading depth, indicate that our sample shows the work hardening behaviour.

关键词： coated conductor buffer layer self-epitaxy CeO2

INTRINSIC EQUATIONS FOR A GENERALIZED RELAXED ELASTIC LINE ON AN ORIENTED SURFACE IN THE GALILEAN SPACE

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Acta Mathematica Scientia 2013年第3期33卷 701-711页

作者： Tevfik sahin Department of Mathematics Faculty of Arts and Sciences Amasya University-TURKEY

In this article, we derive the intrinsic equations for a generalized relaxed elastic line on an oriented surface in the Galilean 3-dimensional space G3. These equations will give direct and more geometric approach to ... 详细信息

关键词： Galilean space generalized relaxed elastic line variational problem intrinsicformulation geodesic

Revealing Importance of Management of Assets in Investment Trust Companies by DEA Analysis

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Transactions of Nanjing University of Aeronautics and Astronautics 2018年第S1期35卷 88-95页

作者： Telli sahin College of Economics and Management Nanjing University of Aeronautics and Astronautics

In this paper,contribution of sources to the efficiency of Turkish investment trust companies is investigated by eight models which are constructed by different combinations of inputs of DEA analyze *** oriented CRS based data envelopment analysis(DEA)and also Malmquist Productivity Index are applied for the time period of 2009—*** of the CRS model are preferred as financial investments,cash and cash equivalents,cost of sales,and total sales while net profit and net sales are outputs of the *** is reached at the conclusion that only management of investments is providing better results than only focusing on cash or cost *** addition,effects and contribution of investment management parameter when it is added to the other ones is found more.

关键词： asset management efficiency Malmquist productivity index data envelopment analysis

Mechanical properties of directionally solidified lead-antimony alloys

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International Journal of Minerals,Metallurgy and Materials 2011年第5期18卷 582-588页

作者： Mevlüsahin Hasan Kaya Department of Physics Faculty of Arts and SciencesNigde UniversityNigde 51200Turkey Department of Science Education Faculty of EducationErciyes UniversityKayseri 38039Turkey

The Pb-17wt% Sb alloy was directionally solidified under two solidification conditions：with different temperature gradients （G=0.93-3.67 K/mm） at a constant growth rate （V=17.50 λm/s） and with different growth rates （V=8.3-497 μm/s） at a constant temperature gradient （G=3.67 K/mm） in a Bridgman *** parameters,such as primary dendrite arm spacing （λ1）,secondary dendrite arm spacing （σ2）,and dendrite tip radius （R）,were *** microhardness （Hv） and ultimate tensile strength （λ） of the directional so-lidification samples were also *** influences of solidification and microstructure parameters on Hv and σwere *** results obtained in this work were compared with similar experimental researches in *** is shown that the Hv and σvalues increase with the increase of G and V,but decrease with the increase of λ1,λ2,and R.

关键词： lead-antimony alloy directional solidification microstructure mechanical properties

Mechanical, electrical, and thermal properties of the directionally solidified Bi–Zn–Al ternary eutectic alloy

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International Journal of Minerals,Metallurgy and Materials 2014年第10期21卷 999-1008页

作者： M.sahin E.adrli Department of Electronics and Automation Technical Vocational School of Sciences Nigde University Department of Physics Faculty of Arts and Sciences Nigde University

A Bi-2.0Zn-0.2A1 （wt%） ternary eutectic alloy was prepared using a vacuum melting furnace and a casting furnace. The samples were directionally solidified upwards at a constant growth rate （V= 18.4 μm/s） under different temperature gradients （G = 1.15-3.44 K/mm） and at a constant temperature gradient （G = 2.66 K/mm） under different growth rates （V= 8.3-500 μm/s） in a Bridgman-type directional so- lidification furnace. The dependence ofmicrostructure parameter （2） on the solidification parameters （G and V） and that of the microhardness （Hv） on the microstructure and solidification parameters were investigated. The resistivity （ρ） measurements of the studied alloy were per- formed using the standard four-point-probe method, and the temperature coefficient of resistivity （α） was calculated from the ρ-Tcurve. The enthalpy （AH） and the specific heat （Cp） values were determined by differential scanning calorimetry analysis. In addition, the thermal conductivities of samples, obtained using the Wiedemann-Franz and Smith-Palmer equations, were compared with the experimental results. The results revealed that, the thermal conductivity values obtained using the Wiedemarm-Franz and Smith-Palmer equations for the Bi-2.0Zn-0.2Al （wt%） alloy are in the range of 5.2-6.5 W/Km and 15.2-16.4 W/Km, respectively.

关键词： ternary eutectic alloys directional solidification microhardness electrical resistivity thermal conductivity

Creep Behaviour of Fe-Mn Binary Alloys

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Chinese Physics Letters 2006年第11期23卷 3037-3040页

作者： O. sahin, N. Ucar Department of Physics Art and Science Faculty Suleyman Demirel University Isparta Turkey

Tensile creep behaviour of fine-grained Fe-Mn binary alloys containing 0.42-1.21 wt. % Mn has been investigated in the temperature range from room temperature to 475K under 10-50 MPa. Tensile tests are carried out with a constant cross-head speed under uniaxial load at a strain rate 10^-4s^-1. Stress exponent and activation energy are determined to clarify deformation mechanism. The obtained variation of steady state creep rate with respect to the applied stress for Fe-Mn binary alloys exhibits two distinct regimes at about 20 MPa, indicating a possible change in creep mechanism. The average stress exponent is approximately 2.2, which is a characteristic of grain boundary sliding in the alloys. The activation energy for plastic flow varies from 135 to 92k J/mol, depending on the Mn content.

关键词： HIGH-TEMPERATURE CREEP STEADY-STATE CREEP PB-SB ALLOYS TRANSFORMATION STRESS