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Magnetic phase diagrams of Fe–Mn–Al alloy on the Bethe lattice

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Chinese Physics B 2017年第2期26卷 86-92页

作者： erhan Albayrak Departmnent of Physics Erciyes University 38039 Kayseri Torke

The magnetic behaviors of the Fe–Mn–Al alloy are simulated on the Bethe lattice by using a trimodal random bilinear exchange interaction（J） distribution in the Blume–Capel（BC） model. Ferromagnetic（J 〉 0） or antiferromagnetic（J 〈 0）bonds or dilution of the bonds（J = 0） are assumed between the atoms with some probabilities. It is found that the secondor the first-order phase boundaries separate the ferromagnetic（F）, antiferromagnetic（AF）, paramagnetic（P）, or spin-glass（SG） phases from the possible other one. In addition to the tricritical points, the special points at which the second- and the first-order and the spin-glass phase lines meet are also found. Very rich phase diagrams in agreement with the literature are obtained.

关键词： bond dilution Bethe lattice bilinear interaction Blume–Capel model spin glass alloy

Comparison of intravenous pantoprazole and ranitidine in patients with dyspepsia presented to the emergency department: a randomized, double blind, controlled trial

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World Journal of Emergency Medicine 2016年第1期7卷 30-34页

作者： Engin Senay Cenker eken Murat Yildiz Derya Yilmaz erhan Alkan Mete Akin Mustafa Serinken Department of Emergency Medicine School of Medicine Akdeniz University Department of Gastroenterology School of Medicine Akdeniz University Department of Gastroenterology Burdur Government Hospital Pamukkale University Hospital Department of Emergency Medicine

BACKGROUND:This study aimed to compare pantoprazole,a proton-pomp inhibitors(PPIs),and ranitidine,a H2 receptor antagonists(H2RA),in ceasing dyspeptic symptoms in the emergency department(ED).METHODS:This randomized,double-blinded study compared the effectiveness of 50 mg ranitidine(Ulcuran®)and 40 mg pantoprazole(Pantpas®),given in a 100 m L saline solution by an intravenous rapid infusion within 2–4 minutes in patients with dyspepsia presented to the *** intensity was measured at baseline,30 and 60 minutes after the drug ***:A total of 72 patients were eligible for the *** these patients,2 were excluded from the study because the initial visual analogue scale(VAS)scores were under 20 mm and 4 were excluded from the statistical analysis because of being diagnosed as having other causes of epigastric pain despite being allocated to one of the study ***-three patients in the pantoprazole group and 33 patients in the ranitidine group were analyzed *** mean age of the patients was36.6±15 years,and 26(39.4%)patients were *** of the groups reduced pain effectively at 30[27.6±28(18 to 37)vs.28.3±23(20 to 37),respectively]and 60 minutes[39.6±39(26 to 53)vs.42.3±25(33 to 51),respectively].There were 13(39.4%)patients in the pantoprazole group and 8(24.2%)patients in the ranitidine group who required additional drug at the end of the study(P=0.186).CONCLUSION:Intravenous pantoprazole and ranitidine are not superior to each other in ceasing dyspeptic symptoms at 30 and 60 minutes in the ED.

关键词： Dyspepsia Pantoprazole Ranitidine Emergency department

Thermal entanglement in two-qutrit spin-1 anisotropic Heisenberg model with inhomogeneous magnetic field

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Chinese Physics B 2010年第9期19卷 183-190页

作者： erhan Albayrak Erciyes University Department of Physics

The thermal entanglement of a two-qutrit spin-1 anisotropic Heisenberg XXZ chain in an inhomogeneous magnetic field is studied in detail. The effects of the external magnetic field （B）, a parameter b which controls the inhomogeneity of B, and the bilinear interaction parameters Jx = Jy ≠ Jz on the thermal variation of the negativity are studied in detail. It is found that negativity N decreases when the values of magnetic field, inhomogeneity b and temperature are increasing. In addition, N remains at higher temperatures for higher values of Jz and lower values of B and b.

关键词： negativity XXZ model thermal entanglement qutrit spin-1 magnetic field

The mixed-spins 1/2 and 3/2 Blume-Capel model with a random crystal field

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Chinese Physics B 2012年第6期21卷 485-489页

作者： erhan Albayrak Erciyes University Department of Physics38039KayseriTurkey

The random crystal field （RCF） effects are investigated on the phase diagrams of the mixed-spins 1/2 and 3/2 Blume-Capel （BC） model on the Bethe lattice. The bimodal random crystal field is assumed and the recursion relations are employed for the solution of the model. The system gives only the second-order phase transitions for all values of the crystal fields in the non-random bimodal distribution for given probability. The randomness does not change the order of the phase transitions for higher crystal field values, i.e., it is always second-order, but it may introduce first-order phase transitions at lower negative crystal field values for the probability in the range about 0.20 and 0.45, which is only the second-order for the non-random case in this range. Thus our work claims that randomness may be used to induce first-order phase transitions at lower negative crystal field values at lower probabilities.

关键词： randomness crystal field Bethe lattice mixed spin bimodal

Thermal Entanglement in a Two-Qutrit Spin-1 Anisotropic Heisenberg Model

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Chinese Physics Letters 2011年第2期28卷 43-46页

作者： erhan Albayrak Erciyes University Department of Physics38039KayseriTurkey

The negativity(N)as a measure of thermal entanglement(TE)is studied for a two-qutrit spin-1 anisotropic Heisenberg XXZ chain with Dzyaloshinskii-Moriya(DM)interaction in an inhomogeneous magnetic field in *** effects of the DM interaction parameter D_(z)on the thermal variation of the N for given values of the external magnetic Reid B,a parameter b which controls the inhomogeneity of B and the bilinear interaction parameters J_(x)=J_(y)≠J_(z)are *** is found that N persists to higher values and to higher temperatures for the higher values of±D_(Z)and for the higher positive values of J_(z),*** the antiferromagnetic(AFM)*** J_(z)<0,the ferromagnetic(FM)case,and D_(z)is small,and if J_(z)is strong enough to compete with D^(z),N *** addition,N declines with the increasing values of B and b.

关键词： Heisenberg interaction bilinear

Spin-1 Blume-Capel model with longitudinal random crystal and transverse magnetic fields:A mean-field approach

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Chinese Physics B 2013年第7期22卷 494-498页

作者： erhan Albayrak Department of Physics Erciyes University

The spin-1 Blume–Capel model with transverse and longitudinal external magnetic fields h, in addition to a longitudinal random crystal field D, is studied in the mean-field approximation. It is assumed that the crystal field is either turned on with probability p or turned off with probability 1 p on the sites of a square lattice. Phase diagrams are then calculated on the reduced temperature crystal field planes for given values of γ=Ω/J and p at zero h. Thus, the effect of changing γ and p are illustrated on the phase diagrams in great detail and interesting results are observed.

关键词： random crystal field transverse field spin-1 Blume–Capel model

The Mixed Spin-1/2 and Spin-1 Ising–Heisenberg Model in the Mean-Field Approximation: a New Approach

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Chinese Physics Letters 2018年第3期35卷 84-88页

作者： erhan Albayrak Erciyes University Department of Physics

Thermodynamic properties of the mixed spin-1 and spin-1/2 Ising-Heisenberg model are studied on a honeycomb lattice using a new approach in the mean-field approximation to analyze the effects of longitudinal Dz and transverse Dx crystal fields. The phase diagrams are calculated in detail by studying the thermal variations of the order parameters, i.e., magnetizations and quadrupole moments, and compared with the literature to assess the reliability of the new approach. It is found that the model yields both second- and first-order phase transitions, and tricritical points. The compensation behavior of the model is also investigated for the sublattice magnetizations, and longitudinal and transverse quadrupolar moments. The latter type of compensation is observed in the literature but its possible importance is overlooked.

关键词： Heisenberg Model in the Mean-Field Approximation The Mixed Spin-1/2 and Spin-1 Ising a New Approach

Bond Dilution Effects on Bethe Lattice the Spin-1 Blume–Capel Model

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Communications in Theoretical Physics 2017年第9期67卷 361-365页

作者： erhan Albayrak Erciyes University Department of Physics

The bond dilution effects are investigated for the spin-1 Blume-Capel model on the Bethe lattice by using the exact recursion relations. The bilinear interaction parameter is either turned on ferromagnetically with probability p or turned off with probability 1 - p between the nearest-neighbor spins. The thermal variations of the order-parameters are studied in detail to obtain the phase diagrams on the possible planes spanned by the temperature （T）, probability （p） and crystal field （D） for the coordination numbers q = 3, 4, and 6. The lines of the second-order phase transitions, To-lines, combined with the first-order ones, Tt-lines, at the tricritical points （TCP） are always found for any p and q on the （T, D）-planes. It is also found that the model gives only Tc-lines, To-lines combined with the Tt-lines at the TCP＇s and only Tt-lines with the consecutively decreasing values of D on the （T, p）-planes for aJ1 q.

关键词： bond dilution spin-l Bethe lattice bilinear interaction Blume-Capel

Phase diagrams of the spin-2 Ising model in the presence of a quenched diluted crystal field distribution

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Chinese Physics B 2012年第11期21卷 114-120页

作者： Ali Yigit erhan Albayrak ankiri Karatekin University Department of Physics Erciyes University Department of Physics

We have investigated the random crystal field effects on the phase diagrams of the spin-2 Blume-Capel model for a honeycomb lattice using the effective-field theory with correlations. To do so, the thermal variations of magnetization are studied via calculating the phase diagrams of the model. We have found that the model displays both second-order and first-order phase transitions in addition to the tricritical and isolated points. Reentrant behavior is also observed for some appropriate values of certain system parameters. Besides the usual ground-state phases of the spin-2 model including ±2, ~1, and 0, we have also observed the phases ±3/2 and ±1/2, which are unusual for the spin-2 case.

关键词： spin-2 model random crystal field effective-field theory isolated critical points andtriciritical points