Mehmet Yıldız - Academia.edu (original) (raw)

Papers by Mehmet Yıldız

Birey ve Toplum Sosyal Bilimler Dergisi, 2019

In mythical narratives, courage and the heroism have an important place. Some gods stand out with... more In mythical narratives, courage and the heroism have an important place. Some gods stand out with their courage and are known for their heroism. Heroism is accepted as a divine value in the world of the man which is shaped according to mythical narratives. Therefore, in the ancient Greek myths, where hard struggles are described, there is(are) always hero(s) at the forefround. In this study, it will be asserted that the heroism of people in Ancient Greek mythology is also imitation of the heroism of gods.

Monitoring the health of glass or carbon fiber reinforced polymer under dynamic loading condition... more Monitoring the health of glass or carbon fiber reinforced polymer under dynamic loading conditions is still a challenge. When metals are tested under dynamic loading conditions, usually a single crack is a source of the failure in the material. On the other hand, composite materials include several damage modes such as transverse cracking, delamination and splitting under the dynamic loading and all of them contribute ultimate failure of the material. Due to the complexity of the damage in composite materials, it is very hard to estimate health or damage state of composite materials. In this study, we propose the usage of a novel embedded biaxial Fiber Bragg Grating sensor system to track the evolution of Poisson’s ratio which can be employed as a reliable damage index in composites. The fatigue experiments on specimen made of biaxial glass fiber infused with resin transfer molding system have shown that signal from novel embedded biaxial sensor system can be easily collected to eva...

The Turkish Journal of Pediatrics, 2021

BACKGROUND Juvenile dermatomyositis associated interstitial lung disease, rarely seen in pediatri... more BACKGROUND Juvenile dermatomyositis associated interstitial lung disease, rarely seen in pediatric age groups, has adverse effects on survival. Anti-melanoma differentiation associated gene 5, one of the identified autoantibodies in juvenile dermatomyositis, preferentially affects the lung tissue and may cause rapidly progressive interstitial lung disease. It is a major cause of mortality in juvenile dermatomyositis. In this case report, we present a pediatric patient diagnosed with juvenile dermatomyositis without anti-melanoma differentiation associated gene 5 antibody positivity. CASE A six-year-old male patient admitted to the Pediatric Intensive Care Unit with symptoms of respiratory failure, 1.5 months after the diagnosis of juvenile dermatomyositis. Thorax computed tomography examination revealed pneumomediastinum, a trace of left-sided pneumothorax, atelectasis on the left posterior lung region, ground-glass opacity, minimal subpleural patchy consolidation, and subcutaneous emphysema especially on the sides of the chest wall. Broad-spectrum antibiotics were started. His nasal swab sample was positive in terms of influenza B; therefore, oseltamivir was added to the treatment. Autoimmune myositis antibodies panel was examined but all of them including anti-melanoma differentiation associated gene 5 antibody resulted as negative. There was no notable reduction in lung infiltrations with the patient`s current treatment regimen. On the 12 < sup > th < /sup > day of Pediatric Intensive Care Unit admission, thorax computed tomography scan revealed progressed radiological lung findings compatible with rapidly progressive interstitial lung disease secondary to juvenile dermatomyositis. Despite intensive medical and extracorporeal treatments such as pulse steroid, intravenous immunoglobulin, methotrexate, cyclophosphamide, rituximab, therapeutic plasma exchange and, extracorporeal membrane oxygenation, the patient died on the 35 < sup > th < /sup > day. CONCLUSIONS Juvenile dermatomyositis patients should be carefully monitored for the development of interstitial lung disease. Rapidly progressive interstitial lung disease with a high mortality may develop shortly after diagnosis, even if the anti-melanoma differentiation associated gene 5 antibody is negative.

Rheumatology International, 2021

The effects of biological disease-modifying antirheumatic drugs (bDMARDs) in the clinical course ... more The effects of biological disease-modifying antirheumatic drugs (bDMARDs) in the clinical course of COVID-19 on children with underlying rheumatologic diseases have not been fully demonstrated. To evaluate the course of COVID-19 infection in patients with rheumatic disease receiving bDMARD treatment. This was a retrospective, multicenter study conducted in pediatric patients infected by SARS-CoV-2 and under bDMARDs therapy. The study population consisted of 113 patients (72 female/41 male). The mean age of the patients was 12.87 ± 4.69 years. The primary diagnosis of the cohort was as follows: 63 juvenile idiopathic arthritis, 35 systemic autoinflammatory diseases, 10 vasculitides, and five cases of connective tissue diseases. The mean duration of the primary disease was 4.62 ± 3.65 years. A total of 19 patients had additional comorbid diseases. Thirty-five patients were treated with canakinumab, 25 with adalimumab, 18 with etanercept, 10 with infliximab, nine with tocilizumab, six with rituximab, four with anakinra, three with tofacitinib, and one with abatacept. The median exposure time of the biological drug was 13.5 months. Seventy-one patients had symptomatic COVID-19, while 42 were asymptomatic. Twenty-four patients required hospitalization. Five patients presented with MIS-C. The hospitalized patients were younger and had a shorter duration of rheumatic disease compared to ambulatory patients, although the difference was not statistically significant. Steroid usage, presence of fever, and dyspnea were more common among the hospitalized patients. A worsening in the course of both COVID-19 and current disease was not noticed under bDMARDs, however, to end with a strong conclusion multicentric international studies are required.

Advances in clinical and experimental medicine : official organ Wroclaw Medical University, 2018

Behçet's disease (BD) is a complex multisystemic disease with an unknown origin, which presen... more Behçet's disease (BD) is a complex multisystemic disease with an unknown origin, which presents with aphthous and genital ulcers, cutaneous lesions, arthritis, ocular lesions, and defects in the gastrointestinal and central nervous systems. In this study, we examined the relationship between serum interleukin-20 (IL-20) levels and disease activity in BD patients. A total of 45 BD patients diagnosed according to the BD diagnosis criteria determined by the International Study Group for Behçet's Disease were included in the study. Out of 45 patients, 17 had inactive BD and 28 had active BD. The control group consisted of 25 healthy subjects. The IL-20 levels of all the groups were detected and compared with each other. Serum IL-20, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels were examined. The IL-20 levels of the active BD patient group were significantly higher than in the control group (p < 0.001) and in the inactive BD patient group (p < 0....

Polymer Testing, 2016

Damage accumulation in Glass Fiber Reinforced Polymer (GFRP) composites is monitored based on Poi... more Damage accumulation in Glass Fiber Reinforced Polymer (GFRP) composites is monitored based on Poisson's ratio measurements for three different fiber stacking sequences subjected to both quasi-static and quasi-static cyclic tensile loadings. The sensor systems utilized include a dual-extensometer, a biaxial strain gage and a novel embedded-biaxial Fiber Bragg Grating (FBG) sensor. These sensors are used concurrently to measure biaxial strain whereby the evolution of Poisson's ratio as a function of the applied axial strain is evaluated. It is observed that each sensor system indicates a non-constant Poisson's ratio, which is a sign of damage accumulation under the applied tensile loading. As the number of offaxis plies increases, transverse strain indicates a notable deviation from linearity due to the formation of transverse cracking, thereby leading to a larger reduction in Poisson's ratio as a function of applied axial strain. Here, it is demonstrated that biaxially embedded FBG sensors are reliable to monitor the evolution of Poisson's ratio, unlike biaxial strain gages which record strain values that can be significantly influenced by the cracks formed on the surface of the specimen.

International journal of dermatology, Jan 21, 2016

Growth differentiation factor-15 (GDF-15), a member of the transforming growth factor-β superfami... more Growth differentiation factor-15 (GDF-15), a member of the transforming growth factor-β superfamily of cytokines, plays an important role in cell growth, signal transduction, and apoptosis regulation. The aim of this study was to evaluate serum GDF-15 levels and their relationships with disease-related variables in patients with Behçet's disease (BD). Forty-six patients diagnosed with BD and 30 demographically matched healthy control subjects participated in the study. GDF-15 levels were measured in blood samples from patients and controls. The Behçet's Disease Current Activity Form (BDCAF) was used to evaluate the disease activity of BD. There were no significant differences between the two groups in C-reactive protein (CRP) level, mean erythrocyte sedimentation rate (ESR), age, body mass index, and mean GDF-15 levels (P > 0.05). Serum GDF-15 levels were positively correlated with findings for peripheral arthritis and CRP, and with BDCAF erythema nodosum, BDCAF arthralgi...

Solid-State Electronics, 2012

We analyze the effect of defects on the polarization stability and switching of epitaxial nanocap... more We analyze the effect of defects on the polarization stability and switching of epitaxial nanocapacitor ferroelectric films on tensile substrates using a thermodynamic approach. Defects are either frozen-in dipoles of the p-type or trapped space charges. The retention of the in-plane ferroelectric polarization does not suffer nearly at all from the possible presence of dead layers or polar defects but is dramatically impacted by relatively high densities of space charge. Switching is a strong function of defects as well as the presence of a bottom electrode. The out-of-plane dielectric displacement exhibits a spike during switching of the in-plane polarization in films with bottom electrodes but nearly disappears otherwise. Such an effect during polarization reorientation along the film plane could be tailored as a sensing signal. The hysteresis and domain characteristics as a function of interface conditions and defects are discussed for BaTiO 3 strained on tensile substrates.

International Communications in Heat and Mass Transfer, 2015

This study presents an analytical solution, for fully developed non-Newtonian fluid flows in circ... more This study presents an analytical solution, for fully developed non-Newtonian fluid flows in circular channels under isoflux thermal boundary conditions based on perturbation techniques. Since the physical properties are generally a function of temperature and may not be assumed constant under certain circumstances, the change in viscosity and thermal conductivity with temperature was taken into account. Viscous dissipation term was also included in the performed analysis. In this study, first closed form expressions for velocity, temperature distributions, and Nusselt numbers corresponding to constant thermophysical properties were given in terms of governing parameters. Then, numerical calculation was performed to obtain the values of Nusselt number and global entropy generation for variable thermophysical properties. The results revealed that neglecting the property variation significantly affects heat transfer characteristics and entropy generation, in which the deviation from the constant physical property assumption may reach up to about 32.6%.

International Journal of Rheumatic Diseases, 2014

The aim of this study was to evaluate sleep quality and the related variables in patients with Be... more The aim of this study was to evaluate sleep quality and the related variables in patients with Behçet&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s disease (BD). One hundred and twelve patients diagnosed with BD and 67 age- and gender-matched healthy controls were enrolled in the study. The Pittsburgh Sleep Quality Index (PSQI) was used for the evaluation of sleep disturbance in all participants. The quality of life (QoL) of all patients were evaluated by Nottingham Health Profile (NHP), and anxiety and depression which were assessed by Hospital Anxiety and Depression Scale (HADS). The patients with BD had significantly higher scores in subjective sleep quality, sleep latency, sleep efficiency, sleep disorder, functional disorder in the morning and total PSQI score compared to the healthy control group. According to Pearson&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s analysis, there was a significantly higher correlation between the anxiety, depression and all components of NHP scores and the total PSQI score. Logistic regression analyses indicated that genital ulcer and arthritis were predictors for poor sleep quality. Sleep quality is disturbed in patients with BD. The lower quality of sleep is greatly associated with anxiety, depression, QoL, genital ulcers and arthritis.

The Pain Clinic, 2004

... MEHMET YILDIZ1,∗ , SEYITHAN TAYSI2, AHMET YILDIZ3, NURI BAKAN2, FATIH AKCAY2 and SEVINC KUSKA... more ... MEHMET YILDIZ1,∗ , SEYITHAN TAYSI2, AHMET YILDIZ3, NURI BAKAN2, FATIH AKCAY2 and SEVINC KUSKAY2 ... Durak I, Canpolat O, Kacmaz M, et al., Antioxidant interferences in superoxide dismutase activity methods using superoxide radical as substrate, Clin Chem Lab ...

Polymers for Advanced Technologies, 2007

... 4. Sullivan S, Gong Y, Hughes J. Liposomes. Elsevier Academic Press: Amsterdam, 2003; 289. 5.... more ... 4. Sullivan S, Gong Y, Hughes J. Liposomes. Elsevier Academic Press: Amsterdam, 2003; 289. 5. Photos PJ, Bacakova L, Discher B, Bates FS, Discher DE. ... J. Contr. Rel. 2003; 90: 323334. 6. Lee JCM, Bermudez H, Discher BM, Sheehan MA, Won YY, Bates FS, Discher DE. ...

Materials Science in Semiconductor Processing, 2009

In this article, we present measurements for the pseudo-optical functions of germanium-rich Si x ... more In this article, we present measurements for the pseudo-optical functions of germanium-rich Si x Ge 1Àx (0.000rxr0.100) single-crystals (grown by Liquid Phase Diffusion; LPD) using spectroscopic ellipsometry and photoreflectance techniques in the energy range of 1.72-3.20 eV. The E 1 interband transition energies are obtained from numerically differentiated optical spectra for various crystal compositions. It was shown that the values of E 1 interband transition energy determined by both the ellipsometric and photoreflectance measurements for germanium-rich Si x Ge 1Àx single-crystals are in agreement with those of bulk SiGe crystals reported in the literature [21-24]. The interband transition energies are found to be in the range of 2.100 and 2.215 eV for the composition values of 0.000rxr0.100. The surface morphology of the crystals assayed via atomic force microscopy shows fibrous surfaces with the average grain size of 250 nm. The measured root-mean-square (rms) roughness and maximum height are in the range of 3.78-5.40 and 32.42-67.84 nm, respectively, with increasing germanium composition.

Journal of Dental Sciences, 2009

Background/purpose: Few data have been published concerning tissue and systemic responses to resi... more Background/purpose: Few data have been published concerning tissue and systemic responses to resinous dental materials. The aim of this study was to compare and evaluate the biocompatibility of four kinds of dental self-etching/priming adhesives by measuring tissue responses, local and systemic tumor necrosis factor (TNF) α expression, and oxidative stress parameters. Materials and methods: Eighty rats were equally divided into 10 groups. Four dental adhesives (Clearfil SE Bond, iBond, Clearfil Protect Bond, and Adper Prompt L-Pop) were applied to connective tissue of the rats. In the control group, rats were operated on with no material being applied. Biocompatibilities of the bonding agents were evaluated according to tissue responses, histopathologic and biochemical TNF-α expressions, and levels of malondialdehyde, glutathione, superoxide dismutase and glutathione peroxidase activities 1 week and 1 month after initiation of treatment. Results: All neutrophil levels and edema formation between the iBond group and the other groups were statistically significant after 1 week. Fibroblast levels in the Clearfil SE Bond group were higher than all other groups. Vascularization levels statistically differed between the Clearfil SE Bond and iBond groups, and between the Adper Prompt L-Pop and control groups. Tissue TNF-α levels statistically differed in all groups other than the control group. At the end of 1 month, the neutrophil level in the iBond group was higher than that in the control group. The differences in fibroblast levels after 1 month were statistically significant between the Clearfil SE Bond and Clearfil Protect Bond groups, and between the control and iBond groups. Tissue TNF-α levels were higher in the iBond, Clearfil Protect Bond, and Adper Prompt L-Pop groups than in the Clearfil SE Bond and control groups. Conclusion: There were no statistical differences in levels of serum TNF-α and oxidative stress parameters in any groups during the course of the study. The four different adhesive systems exhibited different degrees of local toxicity to the subsurface of the skin of rats, but no systemic toxicity was detected.

Glass fiber reinforced composite (GFRC) are widely used in all load bearing industrial applicatio... more Glass fiber reinforced composite (GFRC) are widely used in all load bearing industrial applications. It is therefore critical to understand the fatigue characteristic of GFRC to improve the material characteristics of these composites and to prevent any untoward accidents. In this paper we describe the preliminary results of fatigue test on GFRC fabricated using an in-house laboratory scale resin transfer molding system. The fatigue tests are done for different load conditions–tension compression and reverse bending. ...