Not So Far, Not So Close: A Configurational Study of a Carbon Nanotube Bundle for Better Dielectric Phenomena

Mehmet Orhan 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.11

Size of pores or spacing among nano-protrusions such as nanotubes on an electrode surface greatly affects diffusive, viscous, and dielectric phenomena of electrolyte through openings. In this study, a configurational study was conducted to examine the effect of spacing among the single-walled carbon nanotubes on dielectric and viscous phenomena. Behavior of a polar liquid, acetonitrile, was investigated by molecular simulations at two low densities. Results show that viscosity of the liquid is greatly enhanced by interaction with closely packed tubes' bundle. In conjunction with such increase in viscosity, relaxation of dipoles takes longer times inside such closed packed bundle. Most importantly, spacing among the tubes with diameter D should be at about D/2 in a direction for better dielectric phenomena.

Dielectric and Transport Properties of Acetonitrile at Varying Temperatures: a Molecular Dynamics Study

Orhan, Mehmet Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.5

Use of acetonitrile in electrolytes promotes better operation of supercapacitors. Recent efforts show that electrolytes containing acetonitrile can also function in a wide range of operating temperatures. Therefore, this paper addresses the dielectric relaxation processes, structure and dynamic properties of the bulk acetonitrile at various temperatures. Systems of acetonitrile were modeled using canonical ensemble and simulated by employing Molecular Dynamics method. Results show that interactions among the molecules were correlated within a cut-off radius while parallel and anti-parallel arrangements are observed beyond this radius at relatively high and low temperatures respectively. Furthermore, effects of C-C-N and C-H bending modes were greatly appreciated on the power spectral density of time rate change of dipole-dipole correlations whereas frequency shifts were observed on all modes at the lowest temperature under consideration. Linear variations with temperature were depicted for reorientation times and self-diffusion coefficients. Shear viscosity was also computed with a good accuracy within a certain range of the temperature as well.

Reliability of Fossae Lumbales Laterales and Pelvic Incidence for Estimating Transsacral Corridors Assessed Using Reconstruction Computed Tomography

Orhan Balta,Mehmet Akif Yılmaz,Kürşad Aytekin,Recep Kurnaz,Harun Altinayak,Mehmet Burtaç Eren,Eyüp Çağatay Zengin 대한정형외과학회 2022 Clinics in Orthopedic Surgery Vol.14 No.3

Background: The present study aimed to evaluate the effect of fossae lumbales laterales and pelvic incidence (PI) on transsacral corridors. Methods: Patients who underwent pelvic computed tomography (CT) during routine therapy in a single center between 2015 and 2020 were retrospectively reviewed. The patients’ age and sex were documented during CT examination. Measurements were performed for both the upper and second sacral segments. Height and weight of the patients were determined using appropriate tools and body mass index (BMI) was calculated. Transsacral corridors were identified in true coronal and true sagittal planes and their width was determined as the maximum gap measured so that no screws could come out of the transacral corridors. PI was measured. Results: Our study included 244 (57%) male and 184 (43%) female patients, who had a mean age of 49.3 ± 14.15 years (range, 18–89 years) and a mean BMI of 26.57 ± 2.38 kg/m2. No statistically significant correlation was found between the detection of the dimple sign in physical examination and the presence of an adequate corridor. The PI was statistically significantly higher in the patients with dimples (p < 0.001). PI of the female patients was higher than that of the male patients (p = 0.026). The correlation between PI and the existence of adequate corridors for S1 and S2 screws was not statistically significant (p = 0.858 and p = 0.129, respectively). On the relationship between the presence of adequate S1 and S2 corridors where transsacral screws could be sent, an inverse relationship was detected: if the S1 transsacral corridor was adequate, the S2 corridor was inadequate or vice versa. Conclusions: We could not obtain meaningful results on the use of the dimples of Venus or PI instead of CT to evaluate the adequacy of transverse corridors. Nevertheless, we confirmed that an increased PI was associated with the presence of dimples of Venus.

Dielectric and Transport Properties of Acetonitrile at Varying Temperatures: a Molecular Dynamics Study

Mehmet Orhan 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.5

Use of acetonitrile in electrolytes promotes better operation of supercapacitors. Recent efforts show that electrolytes containing acetonitrile can also function in a wide range of operating temperatures. Therefore, this paper addresses the dielectric relaxation processes, structure and dynamic properties of the bulk acetonitrile at various temperatures. Systems of acetonitrile were modeled using canonical ensemble and simulated by employing Molecular Dynamics method. Results show that interactions among the molecules were correlated within a cut-off radius while parallel and anti-parallel arrangements are observed beyond this radius at relatively high and low temperatures respectively. Furthermore, effects of C-C-N and C-H bending modes were greatly appreciated on the power spectral density of time rate change of dipole-dipole correlations whereas frequency shifts were observed on all modes at the lowest temperature under consideration. Linear variations with temperature were depicted for reorientation times and self-diffusion coefficients. Shear viscosity was also computed with a good accuracy within a certain range of the temperature as well.

Atrial Electromechanical Coupling in Patients with Lichen Planus

Mehmet Yaman,Osman Beton,Lale Dinç Asarcıklı,Aytekin Aksakal,Orhan Dogdu,Uğur Arslan 대한심장학회 2016 Korean Circulation Journal Vol.46 No.4

Background and objectives: A chronic inflammatory disease, lichen planus may cause disturbance of atrial electromechanical coupling and increase the risk of atrial fibrillation. The aim of this study was to evaluate atrial electromechanical delay with both electrocardiography (ECG) and echocardiography in patients with lichen planus (LP). Subjects and Methods: Seventy-two LP patients (43 males [59.7%], mean age: 44.0±16.7 years) were enrolled in this cross-sectional casecontrol study. The control group was selected in a 1:1 ratio from 70 patients in an age and sex matched manner. P wave dispersion was measured by ECG to show atrial electromechanical delay. All of the patients underwent transthoracic echocardiography for measuring inter- and intra-atrial electromechanical delays. Results: The baseline characteristics of the patients and the control group were similar except for the presence of LP. P-wave dispersion measured by ECG was significantly higher in patients with LP (p<0.001). Patients with LP had significantly prolonged intra- and interatrial electromechanical delays when compared to the control group (p<0.001). In addition, all of these variables were significantly correlated with high sensitive C-reactive protein (hsCRP) levels. Conclusion: Atrial electromechanical coupling, which is significantly correlated with increased hsCRP levels, is impaired in patients with LP.

Sepsis and Meningitis due to Listeria Monocytogenes

Orhan Yildiz,Bilgehan Aygen,Duygu Esel,Uner Kayabas,Emine Alp,Bulent Sumerkan,Mehmet Doganay 연세대학교의과대학 2007 Yonsei medical journal Vol.48 No.3

Purpose: This study focused on the effect of immuno-compromising conditions on the clinical presentation of severe listerial infection. Patients and Methods: Nine human listeriosis cases seen from 1991-2002 were reviewed. All adult patients, from whose blood, peritoneal fluid or cerebrospinal fluid (CSF) the L. monocytogenes was isolated, were included in this retrospective study. Results: Listeriosis presented as primary sepsis with positive blood cultures in 5 cases and meningitis with positive CSF cultures in 4 cases. All of these patients had at least one underlying disease, most commonly, hematologic malignancy, diabetes mellitus, amyloidosis and hepatic cirrhosis; 55.6% had received immunosuppressive or corticosteroid therapy within a week before the onset of listeriosis. The patients were adults with a mean age of 60 years. Fever, night sweats, chills and lethargy were the most common symptoms; high temperature (>38℃), tachycardia, meningeal signs and poor conditions in general were the most common findings on admission. The mortality rate was 33.3% and was strictly associated with the severity of the underlying disease. Mortality differences were significant between sepsis (20%) and meningitis (50%) patients. Conclusion: Listeriosis as an uncommon infection in our region and that immuno- suppressive therapy is an important pre-disposing factor of listeriosis. Sepsis and meningitis were more common in this group of patients and had the highest case-fatality rate for food-borne illnesses.

The Association between Whole Blood Viscosity and Coronary Collateral Circulation in Patients with Chronic Total Occlusion

Mehmet Serkan Cetin,Elif Hande Ozcan Cetin,Kevser Gülcihan Balcı,Selahattin Aydin,Emek Ediboglu,Muhammed Fatih Bayraktar,Mustafa Mücahit Balcı,Orhan Maden,Ahmet Temizhan 대한심장학회 2016 Korean Circulation Journal Vol.46 No.6

Background and Objectives: Coronary collateral circulation (CCC) has been attributed as inborn bypass mechanisms supporting ischemic myocardium. Various factors have been postulated in CCC. Whole blood viscosity (WBV) has been an underappreciated entity despite close relationships between multiple cardiovascular diseases. WBV can be calculated with a validated equation from hematocrit and total plasma protein levels for a low and high shear rate. On the grounds, we aimed to evaluate the association between WBV and CCC in patients with chronic total occlusion. Subjects and Methods: A total of 371 patients diagnosed as having at least one major, chronic total occluded coronary artery were included. 197 patients with good CCC (Rentrop 2 and 3) composed the patient group. The poor collateral group consisted of 174 patients (Rentrop grade 0 and 1). Results: Patients with poor CCC had higher WBV values for a low-shear rate (LSR) (69.5±8.7 vs. 60.1±9.8, p<0.001) and high-shear rate (HSR) (17.0±2.0 vs. 16.4±1.8, p<0.001) than the good collateral group. Correlation analysis demonstrated a significant negative correlation between the grade of CCC and WBV for LSR (β=0.597, p<0.001) and HSR (β=0.494, p<0.001). WBV for LSR (β=0.476, p<0.001) and HSR (β=0.407, p<0.001) had a significant correlation with the synergy between percutaneous coronary intervention with taxus and cardiac surgery (SYNTAX) score. A multivariate analysis showed that the WBV for both shear rates were independent risk factors of poor CCC (WBV at LSR, OR: 1.362 CI 95%: 1.095-1.741 p<0.001 and WBV at HSR, 1.251 CI 95%: 1.180-1.347 p<0.001). Conclusion: WBV has been demonstrated as the overlooked predictor of poor coronary collateralization. WBV seemed to be associated with microvascular perfusion and angiogenesis process impairing CCC development

Lack of Any Role of Systemic Inflammatory Responses in Predicting Muscle Invasion by Bladder Cancer

Solakhan, Mehmet,Demirpence, Ozlem,Orhan, Nuri,Yildirim, Omer Aydin,Guzel, Ebru,Yildirim, Mustafa Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.8

Background: The purpose of this study is to evaluate if there is a relation between platelet: lymphocyte ratio (PLR) and neutrophil lymphocyte ratio (NLR) values and tumour histology and spread in bladder cancer cases. Materials and Methods: Bladder cancer patients undergoing TUR-M operation, with histopathologically verified diagnosis, followed-up and treated at the Private Medical Park Gaziantep Hospital between 2010 and 2015, have were included in the study. NLR and PLR values were calculated using complete blood count data obtained at the first presentation. Results: A total of 99 patients were included in the study, 7 (7.1%) women and 92 men (92.9%). When NLR was used as the indicator of systemic inflammatory response (SIR), it was determined that, 52 (52.5%) of the patients were SIR negative and 47 (47.5%) SIR positive. No significant relation could be detected between NLR and tumour grade and muscle invasion (p=0.948, p=0.480). When PLR was used as SIR indicator, it was determined that 71 (71.7%) of the patients were found as negative and 28 (28.3%) as positive. No significant relation could be detected between PLR and tumour grade and muscle invasion (p=0.651, p=0.494). Conclusions: In our study we did not detected a relation between tumour histological behavior and PLR and NLR in bladder cancer. However, NLR and PLR are easily calculated, accessible, inexpensive and simple-to-use laboratory data from whole blood counts.

Anti-Acetylcholinesterase and Antioxidant Assets of the Major Components (Salicin, Amentoflavone, and Chlorogenic Acid) and the Extracts of Viburnum opulus and Viburnum lantana and Their Total Phenol and Flavonoid Contents

Ilkay Erdogan-Orhan,Mehmet Levent Altun,Betül Sever-Yilmaz,Gülçin Saltan 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.4

Some Viburnum species are used for preparation of the traditional drink called gilaburu in Anatolia. In the current study, our goal was to evaluate acetylcholinesterase (AChE) inhibitory and antioxidant activities of the ethyl acetate, methanol, and water extracts prepared from the branches, leaves, and fruits of Viburnum opulus and Viburnum lantana along with salicin, amentoflavone, and chlorogenic acid, three major compounds abundantly found in these species. AChE enzyme inhibition was tested in vitro using an enzyme-linked immunosorbent assay microplate reader at 50, 100, and 200 μL/mL concentrations. Antioxidant activity was examined by ferrous ion chelating capacity, ferric reducing antioxidant power, and β-carotene bleaching assay at 500, 1,000, and 2,000 μg/mL. Total phenol and flavonoid contents of the extracts were also established by Folin-Ciocalteau and AlCl_3 reagents, respectively. Our data revealed that the leaf methanol extract of V. opulus displayed a significantly high inhibitory effect against AChE (57.63 ± 1.23%, 87.41 ± 0.99%, and 93.19 ± 0.87% at 50, 100, and 200 μg/mL, respectively). The extracts of V. lantana exerted higher antioxidant activity.

Association of Insulin Resistance with Overactive Bladder in Female Patients

Hakki Uzum,Mehmet Kalkan,Adnan Yilmaz,Ahu Kemik,Orhan Unal Zorba 대한배뇨장애요실금학회 2012 International Neurourology Journal Vol.16 No.4

Purpose: Metabolic syndrome and obesity have been advocated to be risk factors for the development of overactive bladder (OAB). Additionally, insulin resistance is the underlying mechanism of metabolic syndrome. We aimed to investigate the association of insulin resistance with overactive bladder in female patients. Methods: We prospectively conducted the study in our urology department. Female patients aged between 30 and 76 years old applied to our policlinics with or without OAB symptoms were enrolled. One hundred and twenty-two patients with OAB and 62 age-matched controls without OAB were included into the study. Fasting serum insulin, glucose, high-density lipoprotein (HDL-c), and triglycerides levels were measured. Insulin resistance value was obtained via the homeostasis model assessment of insulin resistance (HOMA-IR) calculator. The chi-square and Mann-Whitney U tests were used to compare differences in variables. Results: Serum insulin level was found higher in female patients with OAB (11.5±6.2 μU/mL) relative to controls (6.4±2.1 μU/mL), statistically significant (P=0.036). In addition, HOMA-IR was significantly found higher in the OAB group, 2.86 (0.76 to 17.04) in comparison to controls, 1.32 (0.67 to 224), P=0.018. High-density lipoprotein cholesterol levels (HDL-c) were significantly found lower in females with OAB. Conclusions: Insulin resistance can be associated to overactive bladder and may play significant role in pathogenesis.