Browsing by Author "Ozturk, S"

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    Electrophysiological detection of exam stress in health schools' students
    Kazdagli, H; Ozel, HF; Ozturk, S; Ceylan, D; Erdeniz, B; Ozbek, M; Semin, MI
    Anxiety is a common issue among university students, many of them experience anxiety, depression, and stress during their school life. This study aimed to compare the acute physiological stress responses of students divided into two groups according to their perceived anxiety levels (positive test anxiety, PTA+, and negative test anxiety, PTA-). Heart rate variability (HRV) and electrodermal activity (EDA) were used to assess stress. Thirty-one healthy volunteers participated in the study. Participants completed anxiety assessments, including the Westside Test Anxiety Scale (WTAS), the State-Trait Anxiety Inventory (STAI), and the Test State Anxiety Inventory (TSAI). Based on their scores, participants were categorized into PTA+ + and PTA- groups. All participants underwent 24-h continuous recordings of pulse and electrodermal activity (EDA) on two separate occasions: one day prior to a written exam and during a designated exam-free day serving as a baseline control. We compared the HRV and EDA data obtained on a regular day and on an exam day between the two groups. Results showed that the PTA+ group had significantly higher heart rate, stress index, low frequency, and short-term detrended fluctuation analysis (DFA alpha 1) on the exam day. The tonic EDA component was also higher in the PTA+ group. Stress-related HRV and EDA parameters were negatively correlated with exam scores. In conclusion, the study found that physiological stress indicators obtained from HRV and EDA are associated with perceived exam anxiety in students.
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    Algal flora of an extremophile ecosystem: Kaklik Cave (Denizli, Turkey)
    Ozturk, S
    Caves are specific ecosystems with both biotic and abiotic characteristics. Turkey has approximately 20,000 caves, and the biology of most of them has yet to be studied. Kaklik Cave is sinkhole-shaped and its entrance is quite large. A mineral-rich spring forms travertine as it enters the cave giving it unique characteristics. The study aims to determine the algal flora of Kaklik Cave. A total of eighty-six taxa were identified. Among them, twenty-one taxa were recorded for the first time as freshwater algal flora of Turkey. Also, the relationships among the most effective environmental parameters, the most frequently found algae taxa composition, and sampling sites were observed.
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    CUTTING-TOOL RECYCLING PROCESS WITH THE ZINC-MELT METHOD FOR OBTAINING THERMAL-SPRAY FEEDSTOCK POWDER (WC-Co)
    Altuncu, E; Ustel, F; Turk, A; Ozturk, S; Erdogan, G
    Various recycling processes for WC-Co cermets from cutting tools, such as chemical modification, thermal modification, the cold-stream method and the electrochemical method have been investigated and some of them are actually employed in industry. However, these conventional methods have many problems to be solved and they are not always established technologies. Therefore, a more economical and high-efficiency recycling procedure needs to be developed. In this study we investigated the applicability of the zinc-melt method (ZMM) for recycling WC-Co as a powder from cutting-tool scraps. It was proven that ZMM is an available technique for recovering the WC powder from the cutting tools. WC-Co powders are recovered and then spray dried, sintered and obtained as a feedstock material for thermal-spray coating processes.
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    Effect of olive mill waste addition on the properties of porous fired clay bricks using Taguchi method
    Sutcu, M; Ozturk, S; Yalamac, E; Gencel, O
    Production of porous clay bricks lightened by adding olive mill waste as a pore making additive was investigated. Factors influencing the brick manufacturing process were analyzed by an experimental design, Taguchi method, to find out the most favorable conditions for the production of bricks. The optimum process conditions for brick preparation were investigated by studying the effects of mixture ratios (0, 5 and 10 wt%) and firing temperatures (850, 950 and 1050 degrees C) on the physical, thermal and mechanical properties of the bricks. Apparent density, bulk density, apparent porosity, water absorption, compressive strength, thermal conductivity, microstructure and crystalline phase formations of the fired brick samples were measured. It was found that the use of 10% waste addition reduced the bulk density of the samples up to 1.45 g/cm(3). As the porosities increased from 30.8 to 47.0%, the compressive strengths decreased from 36.9 to 10.26 MPa at firing temperature of 950 degrees C. The thermal conductivities of samples fired at the same temperature showed a decrease of 31% from 0.638 to 0.436 W/mK, which is hopeful for heat insulation in the buildings. Increasing of the firing temperature also affected their mechanical and physical properties. This study showed that the olive mill waste could be used as a pore maker in brick production. (C) 2016 Elsevier Ltd. All rights reserved.
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    Synergic effect of recycled paper sludge and expanded perlite on the engineering properties of porous clay bricks: A new mathematical modelling approach
    Sutcu, M; Ozturk, S; Gencel, O
    Lightweight bricks produced with addition of different additive materials such as expanded perlite (EP) and recycling paper sludge (RPS) waste have been accomplished by a pug mill. Porous fired bricks were produced by using organic and inorganic additives such as paper waste and expanded perlite as pore-makers. In the experimental study, the seventeen mixture sets were prepared with Box-Behnken experimental design procedure of two additive ratios and firing temperatures. The brick samples were produced with shaping by extrusion method and firing at 850, 950 and 1050 degrees C for two hours after drying. Physical characteristics such as bulk density, apparent porosity and water absorption, and also, compressive strength, thermal conductivity and microstructural properties of brick samples were studied. Influences of process parameters on brick properties were investigated with a detailed neuro-regression analysis. In conclusion, the best brick composition (10 % EP + 10 %RPS by weight) in terms of thermal conductivity corresponding to acceptable mechanical properties was optimized. Accordingly, the compressive strength values of all samples are around 10 to 27 MPa. Also, the samples with high additive content (especially 10 %RPS + 5 %EP sample) exhibited the lowest thermal conductivity value (0.432 W/mK) due to the low firing temperature.
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    Optimization of thermal conductivity and lightweight properties of clay bricks
    Ozturk, S
    As the demand for energy increases worldwide, the construction industry, one of the most energy-intensive sectors, requires lightweight and high-thermal-performance materials. To address this, a multi-objective opti-mization approach was used in this study to identify the most suitable solutions for producing strength-fired clay bricks with low thermal conductivity. Porous bricks were produced with organic waste additives to illustrate the relationship between compressive strength and thermal conductivity. A 3-factor and 3-stage Box-Behnken experimental design was utilized, with a pore-forming additive ratio (0-10% by weight of pine nut shells), firing temperature (850-1050 degrees C), and firing time (2-6 h) as the variables. The fired bricks' physical, me-chanical, and thermal properties were determined using standard analysis methods. The bricks' compressive strength and thermal conductivity functions were generated using neuro-regression systematics. Multiple targets were defined, including minimizing the thermal conductivity and maximizing the compressive strength of the bricks. The genetic algorithm was employed to identify Pareto-optimal solutions, and the final sets of low thermal conductive-strength brick production were chosen based on these solutions. Two sets were proposed to achieve the lowest thermal conductivity, and the results confirmed the validity and feasibility of the optimization study.
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    Investigation of Stem Cell Applications on In Vitro Fertilization in Rats
    Gumurdu, A; Ozturk, S; Aydemir, I; Tuglu, MI
    We aimed to search the effects of bone marrow-derived mesenchymal stem cell-conditioned media on in vitro fertilization by investigation of lifetime of germ cells cleavage, degeneration rates and embryo quality. For this purpose, firstly MSCs were isolated from femurs and tibias of the rat, and cells were cultured until the fourth passage. Sperm and oocytes were collected from male and female rats. Oocytes were added in Human Tuba! Fluid Media (HTFM), Single Step Media (SSM), Alpha-MEM Media (AMM) and Bone Marrow-Derived Mesenchymal Stem Cell-Conditioned Media (CM). Thousand sperm were added into the media which including oocytes. Embryos were allowed to produce by IVF. The development of the embryos vas followed until the 11th day, and the arrest, degeneration rates and alive embryos were established. The embryos readied 2. 4. 8. 16 cells stages and monda stage in the CM. While AMM had a negative effect on fertilization and embryo development. the most favourable effect was shown to be caused by CM in comparison with the other medias. These results have shorn that the beneficial effects of CM in IVF would be a significant increase in the rate of fertility and development of embryos.
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    Synergistic role of three dimensional niche and hypoxia on conservation of cancer stern cell phenotype
    Gorgun, C; Ozturk, S; Gokalp, S; Vatansever, S; Gurhan, SID; Urkmez, AS
    Hypoxia is a pathalogical condition in which tissues are deprived of adequate oxygen supply. The hypoxia effect on tumors has a critically important role on maintenance of cancer stem cell phenotype. The aim of this study is to investigate the effects of hypoxia on cancer stem cells on three dimensional (3D) in vitro culture models. Osteosarcoma stem cells characterized by CD133 surface protein were isolated from osteosarcoma cell line (SaOS-2) by magnetic-activated cell sorting (MACS) technique. Isolated CD133(+) and CD133(-) cells were cultivated under hypoxic (1% O-2) and normoxic conditions (21% O-2) for 3 days. For the 3D model, bacterial cellulose scaffold was used as the culture substrate. 3D morphologies of cells were examined by scanning electron microscopy (SEM); RT-PCR and immunocytochemistry staining were used to demonstrate conservation of the cancer stem cell phenotype in 3D environment under hypoxic conditions. Cell viability was shown by MTT assay on 3. and 7. culture days. This study is seen as an introduction to develop a 3D hypoxic cancer stem cell based tumor model to study CSC behavior and tumor genesis in vitro. (C) 2016 Published by Elsevier B.V.
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    Phase change material incorporated paper pulp sludge/gypsum composite reinforced by slag and fly ash for energy efficient buildings: Solar thermal regulation, embody energy, sustainability index and cost analysis
    Kucukdogan, N; Sutcu, M; Ozturk, S; Yaprak, H; Memis, S; Gencel, O; Ustaoglu, A; Sari, A; Hekimoglu, G; Erdogmus, E
    This study focuses on the reuse of some industrial wastes in the development of innovative building materials and the thermal performance, environmental impacts and cost estimates of the gypsum composite material developed in the case of a phase change material impregnation. Lauryl alcohol (LA) was impregnated into paper pulp sludge (PPS) up to 45 % by weight without leakage to obtain shape-stable composites. The LA impregnated PPS (PPS/ LA) was replaced with PPS at 50 % and 100 % by weight in gypsum composite. Characteristics of shape-stable composites were studied. Also, the physical, mechanical, thermal properties and solar thermoregulation tests of the produced gypsum composites were examined in addition to the embodied energy, CO2 emissions and cost analysis. The melting and solidification enthalpies of PPS/LA were found to be 100.4-100.1 J/g, with only a 0.5 % reduction in latent heat storage capacity after 500 cycles, and approximately 3 % after 1500 cycles. Although the presence of PPS/LA in the gypsum composite caused a slight decrease in compressive strength, it significantly improved solar thermoregulation performance, maintaining ambient temperatures 2.55 degrees C to 5 degrees C warmer at night and 5.3 degrees C to 13.8 degrees C cooler during the day. Gypsum composites containing the PPS/LA offer a suitable alternative for energy-efficient sustainable building application by reusing around 57 % of three different industrial wastes providing a waste-reducing environmental approach and a high level of indoor thermal comfort.
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    The Impact of the COVID-19 Lockdown on the Quality of Life in Chronic Neurological Diseases: The Results of a COVQoL-CND Study
    Sahin, S; Karsidag, S; Cinar, N; Ates, MF; Demir, S; Eren, F; Neyal, A; Ak, AK; Tokcaer, AB; Ataoglu, EE; Akkaya, SN; Demirel, EA; Koc, F; Ozturk, S; Firat, YE; Okluoglu, T; Togrol, E; Erdemoglu, AK; Ergin, N; Sayin, R; Demir, A; Yilmaz, SE
    Background: Coronavirus disease 2019 (COVID-19) pandemic and lockdown period may induce an impairment in quality of life (QoL), disruption in treatment (DIT), and posttraumatic stress disorder (PTSD) in chronic neurological diseases (CNDs). To reach this information, a multicenter, cross-sectional study (COVQoL-CND) was planned. Parkinson's disease (PD), headache (HA), multiple sclerosis (MS), epilepsy (EP), polyneuropathy (PNP), and cerebrovascular disease (CVD) were selected as the CND. Methods: The COVQoL-CND study includes demographic data, the World Health Organization Quality of Life short form (WHOQOL-BREF), and Impact of Event Scale-Revised (IES-R) forms. Results: The mean age of a total of 577 patients was 49 +/- 17 (19-87 years), and the ratio of female/male was 352/225. The mean age of patients with PD, HA, MS, EP, PNP, and CVD were 65 +/- 11, 39 +/- 12, 38 +/- 10, 47 +/- 17, 61 +/- 12, and 60 +/- 15 years, respectively. The IES-R scores were found to be higher in the younger group, those with comorbid disease, contacted with CO-VID-19 patients, or diagnosed with COVID-19. In the group with a high IES-R score, the rate of DIT was found to be high. IES-R scores were negatively correlated with QoL. IES-R total scores were found highest in the CVD group and lowest in the PD group. The ratio of DIT was found highest in the PNP group and the lowest in the EP group. Contact with CO-VID-19 patients was high in the EP and HA group. Conclusions: The results of the COVQoL-CND study showed that lockdown causes posttraumatic stress and deterioration in the QoL in CND.
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    Physicians' knowledge of and opinions about inhaler treatments in asthma and COPD: the INTEDA-1 study
    Caliskaner, Z; Ozturk, C; Pekcan, S; Yilmaz, O; Ozturk, S; Ceylan, E; Can, C; Sener, O; Turay, U; Ersoy, R
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    Development and characterization of cancer stem cell-based tumoroids as an osteosarcoma model
    Ozturk, S; Gorgun, C; Gokalp, S; Vatansever, S; Sendemir, A
    Three-dimensional (3D) cancer tumor models are becoming vital approaches for high-throughput drug screening, drug targeting, development of novel theranostic systems, and personalized medicine. Yet, it is becoming more evident that the tumor progression and metastasis is fueled by a subpopulation of stem-like cells within the tumor that are also called cancer stem cells (CSCs). This study aimed to develop a tumoroid model using CSCs. For this purpose CD133(+) cells were isolated from SaOS-2 osteosarcoma cell line with magnetic-activated cell sorting. To evaluate tumoroid formation ability, the cells were incubated in different cell numbers in agar gels produced by 3D Petri Dish (R) method. Subsequently, CD133(+) cells and CD133(-) cells were co-cultured to investigate CD133(+) cell localization in tumoroids. The characterization of tumoroids was performed using Live&Dead staining, immunohistochemistry, and quantitative polymerase chain reaction analysis. The results showed that, CD133(+), CD133(-) and SaOS-2 cells were all able to form 3D tumoroids regardless of the initial cell number, but, while 72 hr were needed for CD133(+) cells to self-assemble, 24 hr were enough for CD133(-) and SaOS-2 cells. CD133(+) cells were located within tumoroids randomly with high cell viability. Finally, when compared to two-dimensional (2D) cultures, there were 5.88, 4.14, 6.95, and 1.68-fold higher messenger RNA expressions for Sox2, OCT3/4, Nanog, and Nestin, respectively, in CD133(+) cells that were cultured within 3D tumoroids, showing longer maintenance of stem cell phenotype in 3D, that can allow more relevant screening and targeting efficiency in pharmaceutical testing. It was concluded that CSC-based tumoroids are propitious as 3D tumor models to fill the gap between conventional 2D in vitro culture and in vivo animal experiments for cancer research.
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    The extreme errors in inhaler device use: data from the INTEDA-1 study
    Caliskaner, Z; Ozturk, C; Pekcan, S; Yilmaz, O; Ozturk, S; Ceylan, E; Can, C; Sener, O; Turay, U; Ersoy, R
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    Prediction of nano etching parameters of silicon wafer for a better energy absorption with the aid of an artificial neural network
    Kayabasi, H; Ozturk, S; Celik, E; Kurt, H; Arcaldioglu, E
    To enhance energy absorption of photovoltaics, several etching experiments with various parameters were performed. In addition, an Artificial Neural Network (ANN) simulation was utilized to predict chemical nano etching parameters such as masking and etching durations for Silicon (Si) solar cell applications to reach minimum surface reflectance in an optimum etching duration. Experiments were performed with different masking and etching durations to determine the characteristics of surface reflectance of micro textured n-type single crystalline Si wafers in 25mmx25mm width and 300 gm thickness to provide training data for ANN. For this purpose, solutions with identic properties including Ag nanoparticles were applied with different application durations on the surfaces of n-type single crystalline Si wafers to cover partially the Si surfaces with Ag nano-particles at masking step. After, partially masked Si surfaces were exposed to chemical nano etching to develop nano-sized porous structures under different etching durations in an identic acidic etching solution. For the etching of Si wafers, 32 masking and etching processes were performed. Reflectance measurements and SEM images were evaluated to determine the optimum etching duration resulting the best surface quality with minimum reflectance. In addition, reflectance values were utilized as input data for training, testing and validation steps of developed ANN. In the ANN simulation, 70% of reflectance values were used as training, 15% of reflectance values were used as validation and 15% of reflectance values were used to test data in the ANN. Consequently, surface reflectance values under different masking and etching durations were predicted with the new parameter set by using the trained ANN with a success level above 99%.
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    Evaluation and follow-up of patients diagnosed with hypophysitis: a cohort study
    Hacioglu, A; Karaca, Z; Uysal, S; Ozkaya, HM; Kadioglu, P; Selcukbiricik, OS; Gul, N; Yarman, S; Koksalan, D; Selek, A; Canturk, Z; Cetinarslan, B; Corapcioglu, D; Sahin, M; Unal, FTS; Babayeva, A; Akturk, M; Ciftci, S; Piskinpasa, H; Dokmetas, HS; Dokmetas, M; Sahin, O; Eraydin, A; Fenkci, S; Ozturk, S; Akarsu, E; Omma, T; Erkan, B; Burhan, S; Koroglu, EP; Saygili, F; Kan, EK; Atmaca, A; Elbuken, G; Uc, ZA; Gorar, S; Hekimsoy, Z; Pekkolay, Z; Bostan, H; Bayram, F; Yorulmaz, G; Sener, SY; Turan, K; Celik, O; Dogruel, H; Ertorer, E; Iyidir, OT; Topaloglu, O; Cansu, GB; Unluhizarci, K; Kelestimur, F
    Objective Primary hypophysitis might be challenging to diagnose, and there is a lack of evidence regarding optimal treatment strategies due to rarity of the disease. We aim to investigate the clinical features and compare the outcomes of different management strategies of primary hypophysitis in a large group of patients recruited on a nationwide basis.Design A retrospective observational study.Methods The demographic, clinical, and radiologic features and follow-up data were collected in study protocol templates and analyzed.Results One hundred and thirteen patients (78.8% female, median age: 36 years) were included. Lymphocytic (46.7%) and granulomatous hypophysitis (35.6%) were the prevailing subtypes out of 45 patients diagnosed after pathologic investigations. Headache (75.8%) was the most common symptom, and central hypogonadism (49.5%) was the most common hormone insufficiency. Of the patients, 52.2% were clinically observed without interventions, 18.6% were started on glucocorticoid therapy, and 29.2% underwent surgery at presentation. Headache, suprasellar extension, and chiasmal compression were more common among glucocorticoid-treated patients than who were observed. Cox regression analysis revealed higher hormonal and radiologic improvement rates in the glucocorticoid-treated group than observation group (hazard ratio, 4.60; 95% CI, 1.62-12.84 and HR, 3.1; 95% CI, 1.40-6.68, respectively). The main indication for surgery was the inability to exclude a pituitary adenoma in the presence of compression symptoms, with a recurrence rate of 9%.Conclusion The rate of spontaneous improvement might justify observation in mild cases. Glucocorticoids proved superior to observation in terms of hormonal and radiologic improvements. Surgery may not be curative and might be considered in indeterminate, treatment-resistant, or severe cases.
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    Comparative in vitro cytotoxic effects of ornidazole, metronidazole and ciprofloxacin against Trichomonas vaginalis trophozoites
    Inceboz, T; Inceboz, U; Ozturk, S
    A strain of Trichomonas vaginalis, isolated from a patient complaining of vaginal discharge, was incubated and cultivated to compare the in vitro effects of ornidazole, metronidazole and ciprofloxacin on T. vaginalis trophozoites in terms of minimal inhibition concentrations (MICs) and minimal lethal concentrations (MLCs). MIC levels at 24 hours for ornidazole, metronidazole and ciprofloxacin were 50 mg/mL, 50 mg/mL, and 750 mg/mL. Corresponding MLC levels were the same. In this in vitro study, ornidazole was found to be the most effective drug among 3 drugs tested against T. vaginalis trophozoites in terms of MIC and MLC levels. It is interesting to note that ciprofloxacin, although not as effective as the others, also had some cytotoxic effect on T. vaginalis trophozoites.
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    Influence of tea waste concentration in the physical, mechanical and thermal properties of brick clay mixtures
    Ozturk, S; Sutcu, M; Erdogmus, E; Gencel, O
    The sustainability of raw materials used in construction industry consumed large quantities of material has great importance. The use of pore-makers in the brick production is reducing the consumption of clean clay resources as well as lightness of the baked brick body. Many organic or inorganic additives have been used as pore-making in brick production for improving thermal performance. In this study, tea waste (TW) were used at different concentrations in the brick clay mixtures to examine its effects on baked brick properties. In addition to micro-structure investigations, physical, mechanical and thermal properties of bricks produced were investigated. It is concluded that tea waste additive up to 10% in brick body can be used for structural application and isolation while ratios more 10% tea waste additive for only isolation purposes. Tea wastes can be used as a pore-making additive in the brick production. (C) 2019 Elsevier Ltd. All rights reserved.