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Comprehensive analysis of pulsed plasma nitriding preconditions on the fatigue behavior of AISI 304 austenitic stainless steel

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International Journal of Minerals,Metallurgy and Materials 2021年第4期28卷 657-664页

作者： Okan unal Erfan Maleki Remzi Varol Mechanical Engineering Department Karabuk UniversityKarabuk 78050Turkey Modern Surface Engineering Laboratory(MSELAB) Karabuk UniversityKarabuk 78050Turkey Mechanical Engineering Department Sharif University of Technology-International CampusKish Island 79417-76655Iran Mechanical Engineering Department Suleyman Demirel UniversityIsparta 32200Turkey

This study aims to draw an exact boundary for microstructural and mechanical behaviors in terms of pulsed plasma nitriding *** pulsed plasma nitriding treatment was applied to AISI 304 austenitic stainless steel at different temperatures and *** reveal that nitriding depth increased as process temperature and duration *** nitriding depth remarkably increased at 475℃for 8 h and at 550℃for 4 *** austenite structure was transformed into a metastable nitrogen-oversaturated body-centered tetragonal expanded austenite(S-phase)during low-temperature plasma *** S-phase was converted to CrN precipitation at 475℃for 8 h and at 550℃for 4 *** hardness and fatigue limit increased through plasma nitriding regardless of process *** best surface hardness and fatigue limit were obtained at 550℃for 4 h because of the occurrence of CrN precipitation.

关键词： pulsed plasma nitriding S-phase fatigue nitrided layer

Synthesis, characterization and radioluminescence properties of erbium-doped yttria phosphors

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International Journal of Minerals,Metallurgy and Materials 2021年第12期28卷 1983-1990页

作者： Fatma unal Faruk Kaya Kursat Kazmanli Metallurgical and Materials Engineering Department Hitit UniversityCorum 19030Turkey Metallurgical and Materials Engineering Department Istanbul Technical UniversityMaslakIstanbul 34469Turkey

Radioluminescence(RL)behaviour of erbium-doped yttria nanoparticles(Y2O_(3):Er^(3+)NPs)which were produced by sol-gel method was reported for future scintillator *** with dopant rates of 1 at%,5 at%,10 at%and 20 at%Er were produced and calcined at 800℃,and effect of increased calcination temperature(1100℃)on the RL behaviour was also reported.X-ray diffraction(XRD)results showed that all phosphors had the cubic Y2O_(3) bixbyite-type *** lattice parameters,crystallite sizes(CS),and lattice strain values were calculated by Cohen-Wagner(C-W)and Williamson-Hall(W-H)methods,***,the optimum solubility value of the Er^(3+)dopant ion in the Y2O_(3) host lattice was calculated to be approximately 4 at%according to Vegard’s law,which was experimentally obtained from the 5 at%Er^(3+)ion containing *** peak shifts in XRD patterns and X-ray photoelectron spectroscopy(XPS)analyses confirmed that Er^(3+)dopant ions were successfully incorporated into the Y2O_(3) host ***-resolution transmission electron microscopy(HRTEM)results verified the average CS values and agglomerated NPs morphologies were *** electron microscopy(SEM)results showed the neck formation between the particles due to increased calcination *** a result of the RL measurements under a Cu KαX-ray radiation(wavelength,λ=0.154 nm)source with 50 kV and 10 mA beam current,it was determined that the highest RL emission belonged to 5 at%Er doped *** the RL emission spectrum,the emission peaks were observed in the wavelength ranges of 510-575 nm(2H11/2,4S3/2-4I15/2;green emission)and 645-690 nm(4F9/2-4I15/2;red emission).The emission peaks at 581,583,587,593,601,611 and 632 nm wavelengths were also *** was found that both dopant rate and calcination temperature affected the RL emission *** color shifted from red to green with increasing calcination temperature which was attributed to the increased crystallinit

关键词： structure. temperature. solution.

Effect of surfactant on the dielectric and electrorheological properties of zinc borate/silicone oil dispersions

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International Journal of Minerals,Metallurgy and Materials 2019年第12期26卷 1523-1530页

作者： Omer Yunus Gumus Halil Ibrahim unal Bursa Technical University Engineering and Natural Sciences FacultyFiber and Polymer Engineering DepartmentBursa 16310Turkey Gazi University Science FacultyChemistry DepartmentSmart Materials Research Lab.Ankara 06500Turkey

Zinc borate(ZB)particles dispersed in silicone oil(SO)at concentrations of φ=5vol%-20vol% were subjected to dielectric analysis to elucidate their polarization strength,time,and *** revealed that all virgin dispersions lacked *** X-100,a non-ionic surfactant,was added to ZB/SO dispersions to enhance the polarizability of ZB *** addition of 1vol% Triton X-100 enhanced the polarizability of ZB/SO dispersions,and the 15vol% ZB/SO system provided the highest dielectric difference Δε′(the difference in ε′values at zero and infinite frequency,Δε′=ε0–ε∝)of *** electrorheological(ER)activities of the ZB/SO/Triton-X dispersion system were determined through the ER response test,and viscoelastic behaviors were investigated via oscillation tests.A recoverable deformation of 36% under an applied electrical field strength of 1.5 kV/mm was detected through creep and creep recovery tests.

关键词： zinc borate electrorheological fluids dielectric analysis surfactant

Is there an association between Helicobacter pylori in the inlet patch and globus sensation?

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World Journal of Gastroenterology 2010年第1期16卷 42-47页

作者： Hakan Alagozlu Zahide Simsek Selahattin unal Mehmet Cindoruk Sukru Dumlu ayse Dursun Division of Gastroenterology Department of Internal MedicineFaculty of MedicineGazi University Hospital Department of Pathology Faculty of MedicineGazi University Hospital

AIM:To determine the association between Helicobacter pylori(***)and globus sensation(GS)in the patients with cervical inlet patch. METHODS:Sixty-eight patients with esophageal inlet patches were identified from 6760 consecutive patients undergoing upper gastrointestinal endoscopy *** these 68 patients with cervical inlet patches, symptoms of globus sensation(lump in the throat), hoarseness,sore throat,frequent clearing of the throat,cough,dysphagia,odynophagia of at least 3 mo duration was questioned prior to endoscopy. RESULTS:Cervical heterotopic gastric mucosa(CHGM) was found in 68 of 6760 *** endoscopic prevalence of CHGM was determined to be 1%.*** was identified in 16(23.5%)of 68 patients with inlet patch.53 patients were classified as CHGMⅡ.This group included 48 patients with globus sensation,4 patients with chronic cough and 1 patient with *** the patients who were ***(+)in cervical inlet patches had globus ***:Often patients with CHGM have a long history of troublesome throat *** speculate that disturbances in globus sensation are like non-ulcer dyspepsia.

关键词： Barrett’s esophagus Cervical heterotopic gastric mucosa Globus sensation Helicobacter pylori Inlet patch

Dielectric and microstructural properties of YAG:Dy^(3+) ceramics

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Journal of Rare Earths 2018年第12期36卷 1310-1318页

作者： Munirah Abdullah Almessiere Bayram unal Abdulhadi Baykal Department of Physics College of Science Imam Abdulrahman Bin Faisal University Department of Nanomedicine Research Institute for Research & Medical Consultations (IRMC) Imam Abdulrahman Bin Faisal University Department of Software and Computer Engineering Istanbul Sabahattin Zaim University

Yttrium aluminium garnet(Y3Al5O12:YAG) singly doped with Dy3+ at different concentrations was prepared by solid state reactions using repeated heating cycles over the temperature range of 1300-1600 ℃. X-ray powder diffraction analysis confirms the presence of a well-crystallized YAG perovskite phase with cubic structure(by Rietveld refinement). The rare earth dopant is successfully integrated into the YAG host lattice without any major changes in the original structure. The temperature dependence,up to 250 ℃, of the conductivity, dielectric constant, dielectric loss, and loss tangent, at various frequencies of up to 5.0 MHz for undoped and doped crystals is compared to understand the electrical and structural characteristics. The experimental results reveal that Dy3+ dopants in YAG crystal significantly influence the conductivity, dielectric constant, and lossy mechanisms, which is probably due to the 3 d-AI ions and 4 f-Dy ions incorporated at different positions of both tetrahedral and octahedral symmetries in YAG:xDy3+ ceramics.

关键词： Yttrium aluminium garnet(YAG) X-ray diffraction(XRD) Conductivity Dielectric properties Rare earths

Steady State Heat Transfer of Ladle Furnace During Steel Production Process

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Journal of Iron and Steel Research International 2006年第3期13卷 18-20,25页

作者： unal Camdali Murat.Tun Development Bank of Turkey Ankara 06100Turkey Engineering Faculty Yeditepe UniversityIstanbul 81120 KayιsdagιTurkey

The heat transfer analysis was performed for an industrial ladle furnace （LF） with a capacity of 55-57 t in Turkey. The heat losses by conduction, convection and radiation from outer and bottom surfaces, top and ele... 详细信息

关键词： heat transfer ladle furnace refining liquid steel

Improved population mean estimator with exponential function under non-response

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Applied Mathematics(A Journal of Chinese Universities) 2023年第4期38卷 562-580页

作者： Cerenunal Cem Kadilar Department of Statistics Hacettepe UniversityAnkara 06800Turkey

In this article,we consider a new family of exponential type estimators for estimating the unknown population mean of the study *** propose estimators taking advantage of the auxiliary variable information under the first and second non-response cases *** required theoretical comparisons are obtained and the numerical studies are *** conclusion,the results show that the proposed family of estimators is the most efficient estimator with respect to the estimators in literature under the obtained conditions for both cases.

关键词： non-response exponential estimators sub-sampling method population mean

ELECTRORHEOLOGY AND CREEP-RECOVERY BEHAVIOR OF CONDUCTING POLYTHIOPHENE/POLY(OXYMETHYLENE)-BLEND SUSPENSIONS

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Chinese Journal of Polymer Science 2012年第1期30卷 16-25页

作者： Ozlem Erol H.Ibrahim unal Bekir Sari Smart Materials Research Lab Chemistry Department Gazi UniversityAnkaraTurkey

Electrorheological properties and creep-recovery behavior of polythiophene/polyoxymethylene-blend having PT（50%）/POM（50%） composition were *** size,conductivity and dielectric values were measured to be 24.77μm,3.85×10^（-5） S·m^（-1） and 26.75,*** ratio was measured to be 64%at the end of 16 *** effects of dispersed particle volume fraction,external electric field strength,shear rate,frequency and temperature on ER properties and storage modulus of PT/POM-blend/silicone oil（SO） suspensions were *** were observed in the electric field viscosities of the suspensions and thus they were classified as a smart *** thinning non-Newtonian viscoelastic behavior was determined for PT/POM-blend/SO ***,time-dependent deformation was examined by creep-recovery tests and recoverable viscoelastic deformation established.

关键词： Conducting polythiophene/poly(oxymethylene) Blends Electrorheogical fluids Creep-recovery behavior

Effect of Putrescine on Low-Temperature Acclimation in Chlamydomonas reinhardtii

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Phyton-International Journal of Experimental Botany 2022年第3期91卷 583-598页

作者： Muslum S.Inal Dilek unal Bengu Turkyilmaz unal Munir Ozturk Molecular Biology and Genetics Department Faculty of Science and LetterBilecikŞeyh Edebali UniversityBilecik11230Turkey Biotechnology Application and Research Center BilecikŞeyh Edebali UniversityBilecik11230Turkey Biotechnology Department Art and Sciences FacultyNiğdeÖmer Halisdemir UniversityNiğde51240Turkey Botany Department Centre for Environmental StudiesEge UniversityIzmir35100Turkey

Putrescine is reported to be necessary for cold acclimation under low-temperature *** this study,the effect of low-temperature on some physiological and biochemical parameters has been investigated using the green algae Chlamydomonas *** lipid peroxidation rate,amount of Rubisco protein,activities of antioxidant enzymes and gene expression of polyamine biosynthesis(odc2,and spd1),heat shock proteins(hsp70c,hsp90a,and hsp90c),and PSII repair mechanisms(psba,rep27,and tba1)were determined to understand the low-temperature *** putrescine application significantly increased Rubisco protein concentration and catalase enzyme activities under low-temperature ***,real-time RT-PCR results and gene expression analysis showed that polyamine metabolism induced gene expression at low-temperatures in the first 24 *** the same way,the gene expression of heat shock proteins(hsp70c,hsp90a,and hsp90c)decreased under low-temperature treatment for 72 h;however,application of putrescine enhanced the gene expression in the first 24 *** results obtained indicated that molecular response in the first 24 h could be important for cold *** psba and tba1 expressions were reduced under low-temperatures depending on the exposure *** contrast,the exogenous putrescine enhanced the expression level of the psba response to low-temperature at 24 and 72 *** results obtained in this study indicate that putrescine could play a role in the PS II repair mechanisms under low-temperature stress.

关键词： Chlamydomonas reinhardtii cold acclimation heat shock protein low-temperature stress PS II repair putrescine