The effects of the post-annealing temperature on the growth mechanism of Bi2Sr2Ca1Cu2O8+ ∂ thin films produced on MgO (1 0 0) single crystal substrates by pulsed laser deposition (PLD)

The effects of post-annealing temperature were investigated on Bi 2Sr2Ca1Cu2O8+ ∂ thin films deposited on MgO (1 0 0) substrates by pulsed laser deposition (PLD). The structural and superconducting properties of the films have been determined by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature dependent resistivity (R-T), and DC magnetization measurements. The films which were deposited at 600 C were post-annealed in an atmosphere of a gas mixture of Ar (93%) and O2 (7%), at temperature ranging between 800 and 880 C. This resulted in films which exhibited a single phase of 2212 with a high crystallinity (FWHM ≈ 0.16) and texturing along the c-axis, perpendicular to the plane of the substrate. An optimum temperature of 860 C was found for the post-annealing thermal treatment. The critical temperature, TC, of the films was measured as 82 K and the critical current density, JC, was calculated as 3 × 107 A/cm2 for the film annealed at 860 C.Research Fund of Cukurova University (FEF2011D20

THE ROLE OF FOLIC ACID IN THE TREATMENT OF MAJOR DEPRESSIVE DISORDER

Objective: Depressive symptoms are the most common neuropsychiatric manifestation of folic acid deficiency. The objective of this research is to determine the role of folic acid in the treatment of major depressive disorder (MDD). Method: 60 outpatients with MDD and matched 30 healthy controls constituted the sample. The Personal Information Form was used to determine the sociodeniographic features of the patient and the control groups. Hamilton Depression Rating Scale (HDRS) and the criteria of MDD of DSM-IV were used to diagnos the MDD. 30 of the outpatients randomly selected as first group they were given fluoxetine (20 mgs per day), the remainders we given fluoxeline (20 mgs per day) and folic acid (5 mgs per day) as the second group. HDRS was applied lo the patients in 7^th, 14^th, 28^th, 42^th days and to the three groups at the beginning, and was measured serum folic acid levels 0 ^th, 14^th,. 28 ^th, 42^th days. After calculating HDRS scores and serum folic acid levels, the data were run on SPSS. The following statistical analyses were used in order to evaluate the data: variance analysis, student's t test. Mann-Whitney U test and Tukey's test. Result At the beginning, HDRS scores of first, second and control groups were 29.10, 26.93, 7.90 respectively. The mean serum folate levels were lower in the first and the second groups than It, controls. The decrease of HDRS scores were found to be faster in the second group than the first group. However, in 42^nd day, the difference between HDRS scores of the two groups was not significant statistically. Conclusion: As a result, one can say that adding folate to the treatment of MDD may reduce the occurrence and duration of MDD and increase the efficiency of antidepressant treatment

İnce Kirişlerin Elastik Davranışlarının NIY ve RNIY Yöntemleri İle İncelemesi

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2013Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2013Bu çalışmada, ince kirişlerin elastik davranışlarının incelenmesi, ağsız yöntemlerden olan Noktasal İnterpolasyon (NİY) ve Radyal Noktasal İnterpolasyon (RNİY) yöntemleri ile gerçekleştirilmiştir. Her bir yöntemde, iki farklı integrasyon tekniği kullanılmıştır. Standard olarak kullanılan Gauss integrasyon tekniği, Taylor noktasal integrasyon tekniği ile karşılaştırılmış, NİY ve RNİY üzerine etkileri araştırılmıştır. Noktasal direngenlik matrisinin elde edilmesi, Bernoulli-Euler kiriş teorisine göre gerçekleştirilmiştir. Farklı etki alanı büyüklükleri ve farklı RNİY şekil parametrelerinin çözümler üzerine etkileri ayrıca ele alınmıştır. Bir ankastre kiriş problemi, serbest uca tekil yük uygulanarak çözülmüştür. Elde edilen çözümler, ANSYS paket programı kullanılarak sonlu elemanlar yöntemiyle kıyaslanmıştır.In this study, the point interpolation method (PIM) and radial point interpolation method (RPIM) solutions of elastic thin beams are compared by using standard Gaussian integration and a nodal integration based on Taylor series expansion. The effects of integration schemes, support domain sizes and RPIM shape parameters on the convergency are also investigated. Nodal stiffness matrices are obtained using Bernoulli-Euler beam theory. A cantilever beam problem with concentrated load applied on one end is solved and the results are compared with finite element solutions in ANSYS

A Klein Gordon Particle Captured by Embedded Curves

In the present work, a Klein Gordon particle with singular interactions supported on embedded curves on Riemannian manifolds is discussed from a more direct and physical perspective, via the heat kernel approach. It is shown that the renormalized problem is well-defined, and the ground state energy is unique and finite. The renormalization group invariance of the model is discussed, and it is observed that the model is asymptotically free.Comment: Published version, 13 pages, no figures. arXiv admin note: substantial text overlap with arXiv:1202.356

Determination of the carrier concentration in InGaAsN∕GaAs single quantum wells using Raman scattering

Raman scattering from longitudinal optical phonon-plasmon coupled mode was observed in a series of InGaAsN∕GaAs single quantum well samples grown by metalorganic vapor phase epitaxy. The phonon-plasmon mode spectra were fitted with the dielectric constant function based on Drude model that contains contributions from both lattice vibrations and conduction electrons. The carrier concentration is calculated directly from the plasmon frequency, which is obtained from the fitting procedure. An empirical expression for the electron concentration, [n], in InGaAsN∕GaAs samples is determined as [n]≈{2.35×1016(ωm−502)}cm−3, where ωm is the peak of the upper frequency branch, L+, of the phonon-plasmon mode measured in unit of cm−1. The phonon-plasmon coupled mode was also investigated in rapid thermally annealed samples

Excitonic fine structure and recombination dynamics in single-crystalline ZnO

The optical properties of a high quality bulk ZnO, thermally post treated in a forming gas environment are investigated by temperature dependent continuous wave and time-resolved photoluminescence (PL) measurements. Several bound and free exciton transitions along with their first excited states have been observed at low temperatures, with the main neutral-donor-bound exciton peak at 3.3605 eV having a linewidth of 0.7 meV and dominating the PL spectrum at 10 K. This bound exciton transition was visible only below 150 K, whereas the A-free exciton transition at 3.3771 eV persisted up to room temperature. A-free exciton binding energy of 60 meV is obtained from the position of the excited states of the free excitons. Additional intrinsic and extrinsic fine structures such as polariton, two-electron satellites, donor-acceptor pair transitions, and longitudinal optical-phonon replicas have also been observed and investigated in detail. Time-resolved PL measurements at room temperature reveal a biexponential decay behavior with typical decay constants of similar to170 and similar to864 ps for the as-grown sample. Thermal treatment is observed to increase the carrier lifetimes when performed in a forming gas environment

Seismic constraints on the radial dependence of the internal rotation profiles of six Kepler subgiants and young red giants

Context : We still do not know which mechanisms are responsible for the transport of angular momentum inside stars. The recent detection of mixed modes that contain the signature of rotation in the spectra of Kepler subgiants and red giants gives us the opportunity to make progress on this issue. Aims: Our aim is to probe the radial dependance of the rotation profiles for a sample of Kepler targets. For this purpose, subgiants and early red giants are particularly interesting targets because their rotational splittings are more sensitive to the rotation outside the deeper core than is the case for their more evolved counterparts. Methods: We first extract the rotational splittings and frequencies of the modes for six young Kepler red giants. We then perform a seismic modeling of these stars using the evolutionary codes CESAM2k and ASTEC. By using the observed splittings and the rotational kernels of the optimal models, we perform inversions of the internal rotation profiles of the six stars. Results: We obtain estimates of the mean rotation rate in the core and in the convective envelope of these stars. We show that the rotation contrast between the core and the envelope increases during the subgiant branch. Our results also suggest that the core of subgiants spins up with time, contrary to the RGB stars whose core has been shown to spin down. For two of the stars, we show that a discontinuous rotation profile with a deep discontinuity reproduces the observed splittings significantly better than a smooth rotation profile. Interestingly, the depths that are found most probable for the discontinuities roughly coincide with the location of the H-burning shell, which separates the layers that contract from those that expand. These results will bring observational constraints to the scenarios of angular momentum transport in stars.Comment: Accepted in A&A, 27 pages, 18 figure

Stellar ages and convective cores in field main-sequence stars: first asteroseismic application to two Kepler targets

Using asteroseismic data and stellar evolution models we make the first detection of a convective core in a Kepler field main-sequence star, putting a stringent constraint on the total size of the mixed zone and showing that extra mixing beyond the formal convective boundary exists. In a slightly less massive target the presence of a convective core cannot be conclusively discarded, and thus its remaining main-sequence life time is uncertain. Our results reveal that best-fit models found solely by matching individual frequencies of oscillations corrected for surface effects do not always properly reproduce frequency combinations. Moreover, slightly different criteria to define what the best-fit model is can lead to solutions with similar global properties but very different interior structures. We argue that the use of frequency ratios is a more reliable way to obtain accurate stellar parameters, and show that our analysis in field main-sequence stars can yield an overall precision of 1.5%, 4%, and 10% in radius, mass and age, respectively. We compare our results with those obtained from global oscillation properties, and discuss the possible sources of uncertainties in asteroseismic stellar modeling where further studies are still needed.Comment: 46 pages, 10 figures, ApJ accepte