Ahi Evran University

About: Ahi Evran University is a education organization based out in Kırşehir, Turkey. It is known for research contribution in the topics: Density functional theory & Ab initio. The organization has 842 authors who have published 2270 publications receiving 21904 citations.

Long-term functional and sonographic outcomes in Osgood-Schlatter disease

Abstract: To evaluate the sonographic characteristics, functional aspects and life quality of a group of adolescent patients 2 years after having been diagnosed with Osgood–Schlatter disease and compare them with an age-matched healthy control group. The study was conducted on eighteen Osgood–Schlatter patients with unilateral involvement and 14 age-matched healthy controls. The Flaviis classification and patellar tendon characteristics were observed using a GE Logiq 9 scanner. Broad and vertical jump tests were used for jumping performance. The coordination, proprioception, strength and endurance functions were assessed with the Functional Squat System. For the quality of life, the SF-36 questionnaire was used. The Wilcoxon test for the patients’ initial and second-year assessment and Mann–Whitney U test for the comparison between the patient and control groups were used. By the end of second year, 38.9 % of the patients had totally recovered. The patellar tendon lengthened, distal diameter and distal area of the tendon had lessened, and no significant difference was observed between patient and control groups (n.s). Improvements were detected for the bilateral broad jump test scores, the quality of life and coordination of the patients after 2 years (p < 0.05). The average power of endurance and the total work of strength were significantly higher in control group (p < 0.05). According to the sonography results 2 years after diagnosis, nearly half of the patients had totally recovered. Coordination was the only parameter that improved over the 2-year period. The patient group strength and endurance function remained lower than the control group. III.

High-pressure phases of ZrO 2 : An ab initio constant-pressure study

Abstract: The high-pressure behavior of ${\text{ZrO}}_{2}$ is studied using an ab initio constant-pressure technique up to 140 GPa. Two high-pressure phases of ${\text{ZrO}}_{2}$ are predicted through constant-pressure simulations. ${\text{ZrO}}_{2}$ undergoes a first-order phase transformation from the baddeleyite structure to an orthorhombic structure with space group $Pbcm$ at 35--40 GPa. The coordination number of Zr atoms unexpectedly changes from sevenfold to sixfold owing to this phase transformation. Further increase in pressure leads to another first-order phase transformation from the $Pbcm$ structure to a tetragonal one with the space group $P4/nmm$ at 70--80 GPa. In this structure, Zr atoms are ninefold coordinated. These phase transformations should occur around 11 and 38 GPa from enthalpy calculations, respectively.

A valid and reliable tool for examining computational thinking skills

Abstract: The aim of this study was to develop a scale which can be used to measure the computational thinking skills (CTS) of high school students. Validity and reliability testing of the scale was performed with the participation of 785 students. Exploratory and confirmatory factor analysis showed that the five-point Likert scale had a construct consisting of four factors Problem-solving, Cooperative Learning & Critical Thinking, Creative Thinking, and Algorithmic Thinking expressed by 42 items. The factor loadings of the scale varied from .475 to .853. The confirmatory factor analysis performed to reveal the factorial validity of the scale showed that the Chi-square value (?2?=?2679.07; sd?=?815, p?=?0.00) was significant. The fitness index values were found to be RMSA?=?.0075; SRMR?=?.081; NNFI?=?.91; CFI?=?.92; GFI?=?.90; and AGFI?=?.88. The Cronbach's Alpha internal consistency coefficient was .969 for the overall scale. In addition, the stability of the scale was examined to obtain information about its reliability and the test-re-test method was used. It was concluded as a result of the analysis that the scale was a valid and reliable measurement tool which can be used to measure the CTS of high school students.

The C–V–f and G/ω–V–f characteristics of Au/SiO2/n-Si capacitors

Abstract: Au/SiO2/n-Si metal–insulator-semiconductor (MOS) structures with thermal growth oxide layer have been fabricated. The frequency dependence of capacitance–voltage (C–V) and conductance–voltage (G/ω–V) characteristics of these structures have been investigated taking into account the effect of the series resistance and interface states. The C–V and G/ω–V measurements have been carried out in the frequency range of 1 kHz–1 MHz at room temperature. The frequency dispersion in capacitance and conductance can be interpreted in terms of the interface states density (Nss) and series resistance values (Rs). The interface states can follow the ac signal and yield an excess capacitance especially at low frequencies. The values of measured C and G/ω decrease in depletion region with increasing frequencies especially in low frequencies due to a continuous density distribution of interface states. The C–V plots exhibit anomalous peaks due to the Nss and Rs effect. It has been experimentally found that the peak positions in the C–V plot shift towards positive voltages and the peak value of the capacitance decreases with increasing frequency. The effect of series resistance on the capacitance is found appreciable at high frequencies due to the interface state capacitance decreasing with increasing frequency. In addition, the high-frequency capacitance (Cm) and conductance (Gm/ω) values measured under both reverse and forward bias were corrected for the effect of series resistance to obtain the real diode capacitance. Experimental results show that the locations of interface states between Si/SiO2 and series resistance have a significant effect on electrical characteristics of MOS structures.