Browsing by Author "Yildirim S."
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Item A multicenter survey of childhood asthma in Turkey - II: Utilization of asthma drugs, control levels and their determinants(2009) Soyer O.U.; Beyhun N.E.; Demir E.; Yildirim S.; Bingöl Boz A.; Altinel N.; Cevit O.; Karakaş T.; Anlar Y.; Söüt A.; Altintaş D.; Canitez Y.; Büyükdereli Z.; Sekerel B.E.Soyer OU, Beyhun NE, Demir E, Yildirim S, Bingöl Boz A, Altinel N, Cevit O, Karakaş T, Anlar Y, Söüt A, Altintaş D, Canitez Y, Büyükdereli Z and Sekerel BE. A multicenter survey of childhood asthma in Turkey - II: Utilization of asthma drugs, control levels and their determinants. Pediatr Allergy Immunol 2009: 20: 172-179. © 2008 The Authors Journal compilation © 2008 Blackwell Munksgaard Many surveys worldwide have consistently demonstrated a low level of asthma control and under-utilization of preventive asthma drugs. However, these studies have been frequently criticized for using population-based samples, which include many patients with no or irregular follow-ups. Our aim, in this study, was to define the extent of asthma drug utilization, control levels, and their determinants among children with asthma attending to pediatric asthma centers in Turkey. Asthmatic children (age range: 6-18 yr) with at least 1-yr follow-up seen at 12 asthma outpatient clinics during a 1-month period with scheduled or unscheduled visits were included and were surveyed with a questionnaire-guided interview. Files from the previous year were evaluated retrospectively to document control levels and their determinants. From 618 children allocated, most were mild asthmatics (85.6%). Almost 30% and 15% of children reported current use of emergency service and hospitalization, respectively; and 51.4% and 53.1% of children with persistent and intermittent disease, respectively, were on daily preventive therapy, including inhaled corticosteroids. Disease severity [odds ratio: 12.6 (95% confidence intervals: 5.3-29.8)], hospitalization within the last year [3.4 (1.4-8.2)], no use of inhaled steroids [2.9 (1.1- 7.3)], and female gender [2.3 (1.1-5.4)] were major predictors of poor asthma control as defined by their physicians. In this national pediatric asthma study, we found a low level of disease control and discrepancies between preventive drug usage and disease severity, which shows that the expectations of guidelines have not been met even in facilitated centers, thus indicating the need to revise the severity-based approach of asthma guidelines. Efforts to implement the control-based approach of new guidelines (Global Initiative for Asthma 2006) would be worthwhile. © 2008 Blackwell Munksgaard.Item Fabrication and characterization of nanostructured anatase TiO2 films prepared by electrochemical anodization and their photocatalytic properties(Elsevier Ltd, 2015) Yurddaskal M.; Dikici T.; Yildirim S.; Yurddaskal M.; Toparli M.; Celik E.In this study, nanostructured anatase titanium dioxide (TiO2) films were fabricated by electrochemical anodization of titanium first, and then annealed at 500 °C for 2 h. Effect of electrolyte concentration, anodization time and electrolyte temperature on the surface morphology of the resulting TiO2 thin films were investigated. The phase structures, surface morphology and chemical composition were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity tests of the samples were evaluated by the degradation of aqueous methylene blue (MB) solutions under UV light illumination for different periods of time. The results showed that the structure of nanostructured TiO2 films depended strongly on the anodization parameters. It was found that there were micro-scale pores (<10 μm) and nano-scale pores (diameter in the range from 40 to 70 nm) on the anodized titanium surfaces. This study indicated that structures, surface morphology, and surface area of the nanostructured anatase TiO2 films played an important role on their photocatalytic performance. The results clearly proved that nanostructured anatase TiO2 film prepared with optimum process parameters resulted in enhancement of the photocatalytic activity. © 2015 Elsevier B.V.Item Luminescent properties of scintillator nanophosphors produced by flame spray pyrolysis(Elsevier B.V., 2017) Yildirim S.; Karsu Asal E.C.; Ertekin K.; Celik E.In the present work flame spray pyrolysis synthesis and characterization of the nano-scale phosphors; M′-YTaO4 and M′-Y(Ta0.85Nb0.15)O4 have been studied for the first time. Phase and elemental analysis of the produced nanophosphors were carried out by X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS) measurements, respectively. The surface morphology and particle size of the nanophosphors were identified using scanning electron microscopy (SEM). The XRD results reveal that the nanophosphors have monoclinic M′-YTaO4 and M′-Y(Ta0.85Nb0.15)O4 phases belonging to the presence of M´-form of fergusonite structure. The particle sizes of the nanophosphors were found to be in the range of 50–100 nm. The spectroscopic characterization was performed by both radioluminescence (RL) and thermally stimulated luminescence (TSL) measurements after exposure to X-ray irradiation. Also, photoluminescence and decay times were investigated under UV excitation. The nanophosphors can be concluded as appropriate emissive materials for imaging, display and scintillator applications due to the efficient photoluminescence, moderate radioluminescence (RL) and thermally stimulated luminescence characteristics. © 2017 Elsevier B.V.Item Enhanced photocatalytic properties of Sn-doped ZnO nanoparticles by flame spray pyrolysis under UV light irradiation(Turkish Chemical Society, 2018) Yurddaskal M.; Yildirim S.; Dikici T.; Yurddaskal M.; Erol M.; Aritman I.; Celik E.Zinc oxide (ZnO) is widely used in different areas thanks to its unique photocatalytic, optic and electrical properties. Sn doped ZnO nanoparticles were synthesized through flame spray pyrolysis (FSP) technique. The Sn dopant concentrations were 1, 3, 5, 7 and 9 at. % in produced ZnO nanoparticles. The structural analysis of the produced powders was performed by X-Ray Diffraction (XRD) methods. The surface morphology and particle size distribution of the nanoparticles were identified using scanning electron microscopy (SEM), and dynamic light scattering (DLS) techniques. In addition to this, produced photocatalysts were evaluated for degradation of aqueous methylene blue (MB) solutions under UV light irradiation. Sn-doped nanoparticles have superior photocatalytic activity compared to un-doped ZnO. © 2018, Turkish Chemical Society. All rights reserved.Item Effects of Zn-doping on the photocatalytic activity and microstructures of nanocrystalline SnO2 powders(Turkish Chemical Society, 2018) Yurddaskal M.; Yildirim S.; Dikici T.; Yurddaskal M.; Erol M.; Aritman I.; Uygun H.D.E.; Celik E.In this study, undoped and Zn-doped SnO2 nanoparticles in different concentrations were synthesized by flame spray pyrolysis (FSP) technique. The produced particles were post-annealed after FSP process at 600 °C in order to obtain a crystalline structure. The structural analysis of the produced powders was performed by X-Ray Diffraction (XRD) methods. The surface morphology of the nanoparticles was identified using scanning electron microscopy (SEM). In addition, photocatalytic degradation of aqueous methylene blue (MB) solutions were evaluated using undoped and Zn-doped SnO2 nanoparticles under UV light illumination. Photocatalytic degradation of the MB solutions followed the pseudo-first-order-kinetics and the effect of the Zn doping amount on the photocatalytic reaction was investigated. © 2018, Turkish Chemical Society. All rights reserved.Item Dielectrical, optical, and structural characterization of TiO2/PVA nanocomposite films for dielectric applications(Springer International Publishing, 2018) Gultekin S.; Yildirim S.; Celik E.; Arican Alicikus L.Z.In this study, titanium dioxide/poly(vinyl) alcohol (TiO2/PVA) nanocomposite thin films were prepared by a simple spin-coating method for dielectric applications. Structural, morphological, optical, and dielectric properties of samples were analyzed by XRD, SEM, AFM, UV-VIS, and dielectric measurements. The effect of TiO2 nanoparticles on these properties was investigated. It was found that TiO2 nanoparticles lead to increase the crystallinity of nanocomposites. As TiO2 content in the composite structure increases, while average transmittance values decrease, reflectance values increase. The dielectric parameters such as real and imaginary part of complex permittivity which are related to the stored energy and the dissipation (or loss) of energy were significantly affected by the presence of TiO2 nanoparticles. In addition, alternating current (A.C.) conductivity increased with increasing applied frequency. The A.C. conductivity also confirmed that all the samples exhibited the insulator behavior and obeyed the universal power law. © 2018, Australian Ceramic Society.Item Are hormonal agents better than chemo in metastatic castration-resistant prostate cancer?(Istanbul Tip Fakultesi, 2021) Yildirim S.; Erdoğan A.P.OBJECTIVE In this study, we aim to determine which treatment is more appropriate in castration-resistant chemo-therapy-naive patients. Therefore, docetaxel and agents active in the androgen pathway (abiraterone and enzalutamide) were compared retrospectively in patients progressing on androgen deprivation therapy. METHODS The study was designed as a retrospective and multicenter study. Patients from five centers in Turkey were included in the study. The primary endpoint of the study was overall survival (OS) and the second-ary endpoint was progression-free survival. RESULTS Median OS of the docetaxel group was 18.66 months, it was 16.26 months in the hormonal treatment group. There was no statistically significant difference between the groups (p=0.311). Median progression-free survival of the chemotherapy group was 5.6 months, while it was 9 months in the hormonal therapy group. There was statistically significant difference between the groups (p=0.024). CONCLUSION There was statistical difference in progression-free survival in favor of hormonal therapies in our study. The difference did not reflect on OS and there was no difference between hormonal therapies and docetaxel. Heterogeneity in the selection of patients is considered to lead to this result; however, larger randomized controlled studies are needed to determine the most appropriate treatment in these patients. © 2021, Turkish Society for Radiation Oncology.Item Inflammatory Prognostic Index in Metastatic Renal Carcinoma Treated with Nivolumab(College of Physicians and Surgeons Pakistan, 2022) Ekinci F.; Erdogan A.P.; Yildirim S.; Bulut G.; Yilmaz C.; Barutca S.Objective: To evaluate the utility of inflammatory prognostic index (IPI), albumin, c-reactive protein (CRP), and lactate dehydrogenase (LDH) as predictive biomarkers of oncologic outcome in metastatic renal cell cancer (mRCC) patients treated with nivolumab. Study Design: Descriptive study. Place and Duration of Study: Manisa Celal Bayar University, Aydın Adnan Menderes University, Bitlis Tatvan State Hospital and Private Hatay Defne Hospital Medical Oncology Clinics, Turkey, from January 2017 to June 2020. Methodology: Seventy-five mRCC patients treated with nivolumab between January 2017 and June 2020 were enrolled. Several factors were retrospectively investigated, including IPI, CRP, LDH, and albumin level, for their association with progression-free survival (PFS) and overall survival (OS). The IPI was calculated as CRP × NLR/albumin. Univariate and multivariate analyses were performed to assess the prognostic value of relevant factors. Results: When analysed according to the calculated IPI score, it is seen that the group with <2.153 has an OS duration of 96.3 months, while the group with ≥2.153 has a shorter time of 42.9 months (p=0.02). In the analysis performed according to albumin level, it was reported that those with low levels (22.8 months) had worse median OS than those with high levels (92.8 months) (p=0.004). According to the cox regression analysis results, it was determined that those with a high IPI score significantly increased the risk of death compared to those with a low score (HR:2.4, p=0.023). However, this significance could not be confirmed in the multivariate analysis. It was analysed that those with low albumin levels significantly increased the risk of death compared to both univariate analysis (HR:3.3, p=0.007) and multivariate analysis (HR:4.4, p=0.003). Conclusion: Those with high IPI scores and low albumin levels were associated with worse median OS. However, only the multivariate analysis analysed albumin level as an independent prognostic variable. Prospective and more extensive research is needed to consolidate the potential prognostic power of these markers. © 2022 College of Physicians and Surgeons Pakistan. All rights reserved.Item Use of electrochemical techniques for determining the effect of brewing techniques (espresso, Turkish and filter coffee) and roasting levels on total antioxidant capacity of coffee beverage(John Wiley and Sons Inc, 2022) Yildirim S.; Gok I.; Demir E.; Tokusoglu O.In this study, we determined how roasting levels (light, medium, and dark) of Arabica coffee seed and three brewing techniques—decoction methods (Turkish coffee), infusion method (filter coffee), and pressure methods (Espresso)—affect the total antioxidant capacity in a cup of coffee beverage by electrochemical methods such as square wave stripping voltammetry (SWSV), differential pulse stripping voltammetry (DPSV), and cyclic voltammetry (CV). The highest antioxidant capacity was found in espresso coffee prepared with light roasted coffee seeds, as equivalent of rutin and caffeic acid at 9.4 ± 0.2 g/L and 19.7 ± 0.7 g/L, respectively with SWSV on a carbon paste electrode (CPE). The antioxidant capacity of coffee beverages was influenced by the roasting degree, extraction time, and brewing methods, significantly. SWSV, DPSV, and CV voltammetric methods, fast, reliable, fully validated and without any pretreatment, are alternatives to conventional analytical methods for evaluation of antioxidant values in coffee brews. Practical applications: This research will contribute to the literature considerably since we have established that the antioxidant capacity can be measured by electrochemical methods rapidly with high reliable results. According to the study, the brewing method and roasting temperature significantly affected the antioxidant capacity, and thus, it is important to know how brewing methods, roasting temperatures, and other conditions changes the coffee quality. The results can be used to prepare healthy coffee beverages. © 2022 Wiley Periodicals LLC.