Gazi University
  • Ankara, Republic of Turkey, Turkey
Recent publications
In this experimental study, the values and distributions of dynamic tensile force along the polymeric geostrip reinforcements were investigated under stepped increasing sinusoidal excitations with a series of shaking table tests on 1500 mm high or 1/3 scale physical mechanically stabilized earth wall (MSE) model. The effects of the peak ground acceleration ([Formula: see text]), slope angle of the cohesionless backfill material ([Formula: see text]), and stiffness of the polymeric geostrip reinforcement were assessed on both the potential failure surface geometry in the backfill soil and dynamic tensile forces along the lengths of polymeric geostrips. Three potential failure surfaces from the results of shaking table tests in the backfill cohesionless soil were detected as for states of quasi-elastic, plastic, and failure. However, neither the current design codes for MSE walls nor the theoretical recommendations truly reflect potential failure surface geometry in the backfill soil. Additionally, the values and distribution geometry of maximum incremental dynamic tensile forces ([Formula: see text]) on the reinforcements along the height of MSE wall recommended by design codes are not compatible with test results; however, the normalized location of total maximum incremental dynamic tensile force ([Formula: see text]) acclaimed by design codes is consistent with the test results. The traditional pseudo-static limit equilibrium methods result in over conservative horizontal dynamic earth pressure coefficient ([Formula: see text]) values generally as compared with the test results. The slope angle of the backfill material and stiffness of reinforcement have a negligible effect on the potential failure surface geometry; however, incremental dynamic tensile forces, total maximum incremental tensile forces, and horizontal dynamic earth pressure coefficient values increase with an increase in the stiffness of reinforcement and inclination angle of the backfill and peak ground acceleration value.
A fuel/oxidizer mixture can be burned using a colourless distributed combustion (CDC) process to obtain low emissions and homogeneous combustion. As an alternative way, a perforated burner can be designed to achieve homogeneous combustion and low emissions without changing the combustion performance by having entrainment effects on the combustion chamber. In this study, computational fluid dynamics (CFD) 3D modelling was performed in a perforated burner for ammonia/methane fuels in order to obtain the distributed regime and focus on the entrainment effects. In numerical analysis, the eddy break‐up was used as combustion model, k‐Ɛ as turbulence model, and P‐1 as radiation model. In this study, 10% and 20% entrainment rates were provided from the flame holder wall of the perforated burner. The effects of entrainment rates on temperature, velocity, and NO X emission values were examined. According to the results, when the entrainment rate was increased from 10% to 20%, the overall temperature values of ammonia and methane combustion slightly increased by approximately 1.0%, while on the other hand the maximum temperature levels in the near burner zone decreased by about 5.0%. The findings demonstrated that temperature and velocity distributions got more uniform and the flame zones became thinner. This provided a more colourless and invisible flame appearance. In this way, an improvement in the thermal field has been achieved. In conclusion, when the effect of the distributed regime on NO X emission levels was examined, it has been noted that entrainment effects enable the achievement of low emission levels (approximately 9.0%).
The molecular basis of lung cancer is the progressive accumulation of mutations and epigenetic abnormalities leading to the expression of multiple genes with different functions. These changes lead to the weakening of the DNA structure and its greater susceptibility to subsequent mutations. This is caused by irregularities in cell cycle regulation (mutations of protooncogenes and suppressor genes) and disorders in the repair processes in damaged DNA. Several signaling pathways and specific oncogenes are deregulated in lung cancer and are known to influence modifications related to tumorigenesis, including apoptosis, proliferation, cell-cycle progression, and gene expression [1]. These key pathways and oncogenes affect the development and progression of lung cancer as well as prognosis and resistance.
Purpose Overhead squat assessment (OHSA) is a pre-activity dynamic movement analysis tool used to define deviations from an ideal motion pattern which known as compensation. Compensatory movements may result from abnormality in myofascial activity, length-tension relationships, neuro-motor control strategies, osteokinematics and arthrokinematics. The aim of this study is to identify the association between selected biomechanical variables of the ankle, knee, hip, pelvis, torso during OHSA and 16 km/h treadmill running tasks. Methods Thirteen national long distance male runners (17.3 ± 0.5 age (years); 5.89 ± 1.95 experience (years), 57.9 ± 3.7 body mass (kg); 175.4 ± 5.7 height (cm)) participated in this 2controlled laboratory study. Three-dimensional kinematics were collected at 250 Hz using a 9-camera Qualisys motion analysis system (Qualisys AB, Goteborg, Sweden) while participants performed 16 km/h treadmill running and OHSA tasks. Results Correlation coefficients demonstrated that OHSA pelvic anterior tilt angle was in a positive association with foot strike (FS), mid-stance (MS), and toe-off (TO) pelvic anterior tilt angles and MS tibial internal rotation on talus, MS ankle pronation, MS hip internal rotation. OHSA pelvic anterior tilt angle was in a negative association with TO hip extension. OHSA maximal hip adduction was positively correlated with MS and stance maximal knee adduction. FS, MS, stance maximal angular dorsiflexion values were positively correlated with OHSA dorsiflexion. Increased OHSA dorsiflexion angle was negatively associated with TO plantar flexion. OHSA pronation was positively associated with MS and stance pronation. MS hip internal rotation, MS hip adduction angles were increased, and MS ankle dorsiflexion was significantly decreased with the increase of trunk forward lean relative to tibia during OHSA. Conclusions OHSA was associated with some important and dysfunction-related hip, knee and ankle kinematics. Running coaches, may use OHSA as an assessment tool before the corrective training plan to detect injury-related compensation patterns to reduce the risk of injury and improve running technique.
This study investigates the views of students with visual impairments on distance education during the COVID-19 pandemic. The research design of the study is qualitative research. The participants of the study include students with visual impairments. They are studying at different universities where distance education was offered in the fall semester of 2020 in Turkey. We collected the data of the study through a semi-structured interview form. In the analysis of the data collected, content analysis was carried out. According to the results, it has been determined that distance education during the COVID-19 pandemic has both advantages and disadvantages. The benefits of distance education are that the system and course contents used are accessible, the course contents can be listened to again, it is physically easy to listen to the lesson, the evaluations are made in the form of assignment, additional time is given and communication with the instructors is easily facilitated. The disadvantages stated by the students can be as follows: factors related to the distance education system, factors related to the content, aspects concerned with in-term assignments, factors related to exams, psychological and social factors, and communication-related factors.
Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by persistent antiphospholipid antibodies (aPLs) with arterial and venous thrombosis and/or pregnancy morbidity. In recent years, several studies have highlighted the potential role of non-criteria aPL in diagnosing APS patients. This study aimed to determine the association of the presence of non-criteria aPL antibodies to the clinical and laboratory features of patients with a diagnosis of APS. Eighty patients diagnosed with APS and under observation in the rheumatology clinic of Ankara City Hospital were assessed. Patient demographic and clinical features were meticulously recorded. Non-criteria antibodies tested in our center included antiphosphatidylserine IgA, antiphosphatidylserine IgM, beta 2 glycoprotein IgA, anti-cardiolipin IgA, antiphospholipid antibody IgG, and antiphospholipid antibody IgM. Antibodies from patients who were tested for at least one non-criteria antibody were documented. Out of 80 patients, 55 (68.8%) were tested for at least one non-criteria antibody, and 29 of those patients (52.7%) tested positive for at least one non-criteria antibody. The antiphospholipid antibody IgM and the beta 2 glycoprotein IgA were the most commonly tested non-criteria antibodies. Patients with non-criteria antibody positivity had a higher frequency of Ds DNA positivity and low complement (62.0% vs. 35.0%, p = 0.042; 69.0% vs. 38.0%, p = 0.023), respectively. In addition, positivity for anti-cardiolipin IgG and b2 glycoprotein IgG was significantly higher in the group positive for non-criteria antibodies (79% vs. 31%, p ≤ 0.001; 72.0% vs. 19%, p ≤ 0.001). There was no significant difference between the clinical features of patients with at least one positivity for non-criteria antibodies and those without. Systemic lupus erythematosus (SLE) is the most commonly associated disease with APS, being present in approximately 35% of cases [1]. Since the majority of the patient group in our study had APS that was secondary to SLE, non-criteria antibody positivity may be linked to the immunological activity of SLE. Large multicenter studies are necessary to investigate the clinical significance of isolated/combined positivity for criterion/non-criteria aPLs.
Co3O4 nanoparticles (NPs) were formed using hydrothermal synthesis method and various surfactants to study the effect of changing surface morphology on catalytic and antibacterial activities. FT-IR, TEM, SEM, BET, XRD, and XPS analyses were performed to characterize the NPs. It was observed that as the morphology of Co3O4 changes, it creates differences in the reduction efficiency of organic dyes and p-nitrophenol (p-NP), which are toxic to living organisms and widely used in industry. The reaction rate constants (Kapp) for Co3O4-urea, Co3O4-ed, and Co3O4-NaOH in the reduction of p-NP were found to be 1.86 × 10⁻² s⁻¹, 1.83 × 10⁻² s⁻¹, and 2.4 × 10⁻³ s⁻¹, respectively. In the presence of Co3O4-urea catalyst from the prepared nanoparticles, 99.29% conversion to p-aminophenol (p-AP) was observed, while in the presence of the same catalyst, 98.06% of methylene blue (MB) was removed within 1 h. The antibacterial activity of Co3O4 particles was compared with five standard antibiotics for both gram-positive and gram-negative bacteria. The results obtained indicate that the antimicrobial activity of the synthesized Co3O4 particles has a remarkable inhibitory effect on the growth of various pathogenic microorganisms. The current work could be an innovative and beneficial search for both biomedical and wastewater treatment applications.
The aim for this research was to evaluate and compare the impact, bond strength, and residual adhesive on the enamel surface after debonding of different orthodontic molar tubes. The tested materials were metal, composite, and newly introduced ceramic orthodontic molar tubes. In all, 66 first molar teeth were randomly divided into three groups. Metal, glass-fiber composite and ceramic orthodontic molar tubes were bonded and shear bond strength (SBS) tests were performed. The adhesive remnant index (ARI) scores after debonding were recorded and the enamel surfaces were investigated using scanning electron microscopy (SEM) after the adhesives were cleaned. The mean SBS values of the metal and ceramic tube groups were significantly higher than that of the glass-fiber composite tube group. The highest SBS values were recorded for the ceramic tube group (11.09 ± 2.51 MPa). Failure typically occurred at the adhesive–enamel interface in the ceramic group, whereas the majority of the samples in the glass-fiber composite group showed failure at the adhesive–tube base interface according to ARI and SEM investigations. ARI 1 and ARI 2 scores were commonly observed for the metal tube group. All the molar tubes tested had generated clinically acceptable SBS values; however, the values for glass-fiber composite molar tubes were significantly lower than those for the ceramic and metal molar tubes. If the debonding procedure is performed carefully, the ceramic molar tubes may be an enamel-safe product for patients seeking fully esthetic orthodontic treatment.
A BSTRACT Background and Aim Fiber posts are widely used in endodontically treated teeth with extensive loss of coronal structure. The purpose of this study was to investigate immediate and the long-term effects of chlorhexidine (CHX) and benzalkonium chloride (BAC) application, on the push-out bond strength of fiber posts. Material and Methods Sixty mandibular premolars were decoronated, and root canal treatment was performed. After post space preparation, the specimens were divided into three groups according to the post space-surface pretreatment (n = 20); no surface treatment (control group—Group 1), 2% CHX application (Group 2), and 1% BAC application (Group 3). A self-curing adhesive cement and an etch and rinse adhesive were used for the cementation of posts. Three sections (one cervical, one middle, and one apical) of 1 mm thickness were prepared from each specimen. A push-out test was performed immediately on the half of the specimen sections (n = 10). The other half of the specimen sections were subjected to 20.000 thermal cycles before applying the push-out test (n = 10). The failure mode of each specimen was observed under a stereomicroscope at ×40 magnification. Results The data were analyzed by one-way analysis of variance (ANOVA), Tukey Honestly significant difference (HSD), and Tamhane tests ( P = 0.05). The cervical thirds displayed the highest, and the apical thirds showed the lowest values in all groups ( P < 0.05), except the control-aged group ( P = 0.554). The aged control groups’ values were found to be significantly lower than the aged CHX and BAC groups ( P < 0.001). Aging significantly reduced the bond strength values of specimens in control groups ( P < 0.001). However, aging did not significantly affect the push-out bond strength values of CHX and BAC groups ( P > 0.050). The failure types were adhesive between the post and cement (type 1) in all groups, except control-aged group (type 2). Conclusion The application of 2% chlorhexidine or 1% BAC may be an essential step that can be taken to preserve the bond strength of fiber posts.
In this study, the effect of coating p-Si substrates with a pure ZnO layer using the hydrothermal reaction method on the dielectric parameters was reported. The studied dielectric properties of the ZnO/p-Si structure include dielectric constant (ε′), dielectric loss (ε″), ac electrical conductivity (σ AC), and real and imaginary electrical modulus (M′, M″). These properties were investigated using experimental capacitance-frequency (C-f) and conductivity-frequency (G-f) measurements in a frequency range of 20 Hz-1 MHz and a temperature range of 300-420 K. Experimental results show that dielectric parameters are strongly frequency- and temperature-dependent. The dielectric constant showed an increase of about 11 times in the investigated temperature range. At the same time, AC electrical conductivity increased with increasing frequency and temperature. In addition, the electrical modulus was examined, and peaks were observed in M″ values. It was observed that the peaks shifted to the high-frequency region with the increase in temperature. The activation energies were also calculated from the conductivity parameters and a decrease was observed in the activation energies as the frequency increased. Regardless of temperature and frequency, the higher dielectric loss of the fabricated diode compared to its dielectric constant can be advantageous for certain heating or electromagnetic absorption applications.
Carbitol acetate (CA) could be a remarkable for CO2 absorption due to its high boiling point, low viscosity, and high CO2 solubility. Using a laboratory-scale Raschig ring packed-column, mass transfer studies of CO2 in carbitol acetate have been performed at ambient temperature and pressure. Liquid and gas side physical individual mass transfer coefficients (kL0a, kc0a) were determined by oxygen desorption method and by sulfur dioxide absorption into sodium hydroxide solution (NaOH), respectively. Also, gas side overall chemical and physical mass transfer coefficients (Kca, Kc0a) were experimentally determined by the CO2 absorption into NaOH solution and CA. Results show that Kca and Kc0a increase with increasing gas and liquid velocities. The results also showed that (Kc0a)CA and (Kca)NaOH were 2.2 and 2.5 times greater than that of water, respectively. It is known that the chemical absorption mechanism is more effective than the physical absorption mechanism. According to the (Kc0a)water comparison, (Kc0a)CA and (Kca)NaOH have almost shown close results. Carbitol acetate has been shown to be a potential absorbent for CO2 absorption process and could be a viable alternative with further research and development. Also, nonlinear regression analyses were performed, and correlations were developed for mass transfer coefficients.
A white rot fungus “Lentinus sajor-caju” was immobilized in Ca-alginate beads via entrapment. This method was used to increase fungal biodegradation activity and to allow immobilized fungal recycling and reuse. The mechanical strength of the fungal biomass–immobilized Ca-alginate beads was stable about 95%. The degradation rates of the three different phenolic compounds (i.e., phenol, diclofenac, and pentachlorophenol) from synthetic wastewaters were studied using the immobilized L. sajor-caju. Under optimized conditions, the biodegradation performance of the immobilized fungal biomass was studied in a packed bed reactor at different substrate concentrations. The degradation rates of the immobilized L. sajor-caju for phenol was 100% for 60 h, while for diclofenac and pentachlorophenol were found to be 87 and 51% when incubated for 120 h at 30 °C and determined by high performance liquid chromatography (HPLC). The toxicity of the phenol, diclofenac, and pentachlorophenol and their degradation products was evaluated by using three different bio-indicators organisms: (i) Daphnia magna (a freshwater microcrustaceane), (ii) a fresh water green alga Chlamydomonas reinhardtii, and (iii) Triticum aestivum L. (Turkish winter wheat). In addition, the reusability and efficiency of the same immobilized biomass were tested in successive biodegradation studies in the continuous system. These results suggest that the immobilized L. sajor-caju for degrading phenol, diclofenac, and pentachlorophenol can provide a cheap and easy approach for the removal of phenolic compounds.
Objective To determine the rate of unintentional monotherapy (UM; switching to monotherapy from combination therapy of patients' own volition) in rheumatoid arthritis patients receiving tofacitinib and to evaluate tofacitinib survival rate. Methods This national, multicenter study included patients' data from the TURKBIO Registry. Demographics, clinical characteristics, disease duration and activity, comorbidities, and treatments were analyzed. Results Data of 231 rheumatoid arthritis patients (84.8% female, median age, 56 years) were included; 153 were initially prescribed combination therapy and continued to their therapies; 31 were initially prescribed combination therapy but switched to monotherapy of their own volition (UM); 21 were initially prescribed monotherapy and switched to combination therapy; 26 were initially prescribed monotherapy and continued to their therapies. The rate of comorbidities at the time of data retrieval was higher in the UM group than in the combination group (83.3% vs. 60.3%, p = 0.031). Presence of comorbidities was a significant factor affecting switching to monotherapy ( p = 0.039; odds ratio, 3.29; 95% confidence interval, 1.06–10.18). The combination and UM groups did not differ regarding remission rate assessed by Disease Activity Score 28-joint count C-reactive protein (60.5% and 70%, respectively; p = 0.328). Drug survival rates of the UM and combination groups did not differ. The median drug survival duration of tofacitinib was 27+ months with 1- and 4-year drug survival rates of 89.6% and 60.2%, respectively, in the UM group. Conclusions Although 13.4% of the study population started monotherapy unintentionally, drug survival and remission rates of the UM and combination groups were not different. Comorbidity was a factor affecting transition from combination therapy to monotherapy.
Objectives Neuroleptic malignant syndrome (NMS) is a life-threatening condition that occurs as an adverse reaction to antipsychotic and antiemetic agents or sudden withdrawal of dopaminergic medications. Given the metabolic and functional reserves and the comorbidities in older adults, NMS may show an atypical course. Methods The medical records of patients with neurodegenerative diseases leading to dementia between 2013 and 2020 were reviewed for the diagnosis of NMS. Demographic and clinical characteristics of the patients were obtained from the records of laboratory parameters, management, and length of stay. Results Fifteen older adults (19 episodes) diagnosed with NMS were included. The median age was 76 years, and 5 were female. Ten of 15 NMS patients were atypical. Most of them had an infection accompanying NMS. Neuroleptic malignant syndrome was caused by antidopaminergic agents (5 antipsychotics, 1 metoclopramide) in 6 episodes and discontinuation of a dopaminergic agent, l -DOPA, in 12 episodes. In 1 patient, it was associated with simultaneous use of domperidone and amantadine withdrawal. Rigidity in NMS due to l -DOPA discontinuation was higher than in those due to antipsychotic use ( P = 0.027). Two of our patients needed intensive care, and 1 died. Conclusions This study highlights the high frequency of atypical NMS and the importance of early recognition of this potentially fatal syndrome, which can accompany neurodegenerative diseases and infections in older adults.
Objective Sustainable diet is one of the main factors that support food security, and the Mediterranean diet (MD) one of the sustainable diet models associated with low ecological impact and optimum health results, has come to the fore. It was aimed to compare the results of the 2010 and 2017 Turkish Nutrition and Health Studies (TNHS) according to the Mediterranean Adequacy Index (MAI) and in order to evaluate the environmental impact of the current nutritional status in Turkey through water footprints (WFs). Design The MAI score was calculated using the published results of the 2010 and 2017 TNHS, and the WFs have been calculated as indicators of environmental impact. Setting Turkey. Participants There are no participants. Results In the TNHS, there was an increase in the amount of energy provided by foods non-MD in 2017 compared to 2010, with a decrease in the total MAI score. The group with the lowest adherence to the MD in both years was the adult group (MAI 2010 2.74 and MAI 2017 2.31), while the group with the highest adherence was the adolescent group (MAI 2010 3.21 and MAI 2017 2.53). The MAI scores of females were higher than those of males in both years. The males aged 19-64 years had the largest (841 m ³ /year) WF and the females aged 65+ years had the smallest (483 m ³ /year). The food group that contributed the most to WF was meat and meat products (21.0-35.0%). Conclusions Adherence to the MD has decreased due to the increase in the consumption of the Western-type diet in Turkey.
Using restriction levels and interval type-2 fuzzy sets into linguistic summarization evaluation is a novel strategy presented in this paper. The uncertainty and ambiguity in the linguistic summaries are handled by the suggested method by using interval type 2 fuzzy sets. While it complies with the requirements that evaluation methods should meet, the suggested method additionally makes use of restriction levels to offer a more reliable evaluation framework. On the basis of real-world data, the proposed method’s efficacy is shown. The findings demonstrate that the suggested approach can offer a thorough and precise evaluation of the linguistic summary techniques. The suggested method can assist practitioners and researchers in evaluating linguistic summaries results in a simple yet consistent fashion.
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10,356 members
Türker Kurt
  • Faculty of Education
Hakan Ciftci
  • Department of Physics
Abdullah Hasbenli
  • Department of Biology
Teknikokullar, 06500, Ankara, Republic of Turkey, Turkey
Head of institution
Gazi University