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The electrical properties of high‐purity magnesium oxide (MgO) samples sintered between 1500 and 1650°C were investigated up to 800°C. Dielectric constant, loss tangent and electrical conductivity were measured between 25 and 800°C. Optimum electrical properties were obtained for the sample sintered at 1600°C. The impurities in polycrystalline and single crystal MgO were discussed to understand their effect on electrical properties and the role of grain boundaries. Higher dielectric losses of polycrystalline samples as compared to the single crystal MgO were attributed to the presence of grain boundaries. MgO could be a useful dielectric material for capacitor applications up to 600°C. [ABSTRACT FROM AUTHOR]

To explain the observed X-ray data in a black hole–accreting matter system and understand the physical mechanisms behind QPOs, we have numerically modeled the dynamical and oscillation properties of the shock cone formed around both slowly and rapidly rotating Hartle–Thorne black holes, resulting from the mechanism of Bondi–Hoyle–Lyttleton (BHL). According to the numerical simulations, an increase in the quadrupole parameter leads to a decrease in the shock cone opening angle around the black hole. A larger quadrupole parameter results in more matter falling into the black hole within the cone. The combination of the quadrupole parameter and black hole rotation causes the matter inside the cone to exhibit chaotic motion. These dynamical changes and chaotic behavior of the shock cones excite the fundamental oscillation modes. Moreover, new frequencies have been formed due to the nonlinear coupling of the fundamental modes. Conversely, we have numerically studied the behavior of cones formed around rapidly rotating Hartle–Thorne black holes and found differences and similarities to those obtained from slowly rotating cases. Finally, comparing the outcomes obtained fromHartle–Thorne gravity with the results fromKerr and Einstein–Gauss–Bonnet (EGB) gravities reveals the impact of the quadrupole parameter on the shock cone and QPOs. [ABSTRACT FROM AUTHOR]

The dielectric properties of single crystal and polycrystalline SrTiO3 (ST) were investigated from 295 to 4 K. Relative permittivity (εr) and loss tangent (tan(δ)) were measured systematically as a function of direct current (DC) voltage (0 V/cm to 800 V/cm), frequency (100 Hz to 1 MHz), and temperature (295 K to 4 K) for type (100) single crystal SrTiO3 (SC-ST) and for polycrystalline SrTiO3 (PC-ST). Calculated equivalent series resistance (ESR) data are also reported. Overall, the permittivity of ST showed a dependence on temperature, DC voltage, and frequency. Dependences on voltage and frequency were only observed at temperatures below about 40 K. Curie–Weiss temperature (Tcw) was found to be independent of measurement frequency and applied DC field for SC-ST and PC-ST. Two frequency-dependent ESR peaks were observed for the SC-ST. There were five such peaks for PC-ST including the same two peaks displayed by SC-ST. All loss peaks were found to follow an Arrhenius type behavior. While certain peaks might be related to structural phase transitions, the additional peaks observed for PC-ST were attributed to the presence of grain boundaries, domains, residual porosity, impurities, or their combined effects. The results provide a good prediction of the dielectric performance of SrTiO3 based capacitors towards optimizing the design of circuits used for cryogenic electronic applications. [ABSTRACT FROM AUTHOR]

The electrical properties of dense, high purity CaZrO3 discs, sintered at 1380°C with and without added ZrO2, were investigated up to 950°C. Dielectric constant, loss tangent, and electrical conductivity were measured from 25 to 725°C, and the real and imaginary impedances were measured between 800 and 950°C by impedance spectroscopy techniques. Dielectric constant increased by 8% above 300°C and loss tangent increased from.1% at 25°C to ∼2% above 300°C. Activation energy of electrical conductivity determined between 300°C and 950°C by alternative current (AC) and direct current (DC) measurements. These results indicate that CaZrO3 could be a useful dielectric material for capacitor applications up to 500°C. A reported decrease in conductivity due to addition of excess ZrO2 into stoichiometric CaZrO3 could not be confirmed. [ABSTRACT FROM AUTHOR]

Understanding the physical structures of the accreted matter very close to a black hole in quasars and active galactic nucleus (AGN) is an important milestone to constrain the activities occurring in their centers. In this paper, we numerically investigate the effects of the asymptotic velocities on the physical structures of the accretion disk around the Kerr and Einstein–Gauss–Bonnet (EGB) rapidly rotating black holes. The Bondi–Hoyle accretion is considered with a falling gas towards the black hole in an upstream region of the computational domain. Shock cones are naturally formed in the downstream part of the flow around both black holes. The structure of the cones and the amount of the accreted matter depend on asymptotic velocity V ∞ (Mach number) and the types of the gravities (Kerr or EGB). Increasing the Mach number of the in-flowing matter in the supersonic region reduces the shock opening angle and the accretion rates, because of the gas rapidly falling towards the black hole. The EGB gravity leads to an increase in the shock opening angle of the shock cones while the mass-accretion rates d M / d t decrease in EGB gravity with a Gauss–Bonnet (GB) coupling constant α. It is also confirmed that accretion rates and drag forces are significantly altered in the EGB gravity. Our numerical simulation results could be used in identifying the accretion mechanism and physical properties of the accretion disk and black hole in the observed X-rays such as NGC 1313 X-1 and 1313 X-2 and MAXI J1803-298. [ABSTRACT FROM AUTHOR]

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a common environmental contaminant that is toxic to brain, heart, kidney and liver. TCDD toxicity is due to free radical formation. Beta-glucan is an antioxidant that exhibits beneficial effects on health. We investigated the effects of beta-glucan on brain and liver tissues of rats with TCDD induced toxicity. We used female rats divided into four groups: control, TCDD group treated with TCDD 2 µg/kg/week, beta-glucan group treated with 50 mg/kg/day beta-glucan for 3 weeks, TCDD + beta-glucan group treated with 2 µg/kg/week TCDD and 50 mg/kg/day beta-glucan together for 3 weeks. We found that the thiobarbituric acid reactive substance (TBARS) levels were increased significantly in the TCDD group compared to the other groups. Glutathione (GSH) levels, and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were reduced in the TCDD group compared to the control group. SOD, CAT, GPx activities and GSH levels were increased in the TCDD + beta-glucan group. Histopathological observations were consistent with our biochemical findings. The oxidative stress and histopathology caused by TCDD were ameliorated by beta-glucan treatment. Beta-glucan should be explored for preventing brain and liver damage caused by TCDD toxicity. [ABSTRACT FROM AUTHOR]

Due to its rheological properties, positive lead‐acid battery paste can be difficult to spread on lead current collectors accurately and efficiently under industry machinery and setting. Sodium polymethacrylate dispersant was studied as an effective positive paste additive that could lower the yield stress of the paste without affecting paste density and battery performance. Under a four‐blade vane rheometer setup, stress growth and oscillatory amplitude strain sweep experiments evaluated the rheological properties of positive paste with the addition of varying amounts of sodium polymethacrylate. Further, the electrochemical effects of sodium polymethacrylate were also evaluated in 2V batteries by testing positive active material utilization and cycle life. [ABSTRACT FROM AUTHOR]

Aim: Large breasts create psychological and physical problems in women, all of whom must also keep in mind the common problem of breast cancer. In the present study we examine the effect of breast reduction surgery on breast cancer risk. Materials and Methods: Our retrospective study is based on the records (between June 1, 2014, and June 30, 2019) of patients who underwent breast reduction surgery in the Plastic, Reconstructive and Aesthetical Surgery clinic of a training and research hospital. Statistical analyses were conducted using IBM SPSS Statistics (Version 25.0. Armonk, NY: IBM Corp.). Normal distribution of the data was analyzed with Kolmogorov-Smirnov. The data assessment included descriptive statistical methods and Kruskal-Wallis test. The results were evaluated at a 95% confidence interval and a significance level of p < 0.05. Results: Of the 134 patients included in the study, 47% were aged 36-50 years and 60.4% had a body mass index of -40. The shortest follow-up was 4 years, the longest follow-up was 9 years and the mean follow-up was 5.5 years. The mean amount of tissue removed from the right breast was 1050.54±484.90, the mean amount of tissue removed from the left breast was 1059.54±522.28, and the mean length of hospital stay was 1.15±0.74 days. The pedicle of choice was superomedial in 55.2% and the inverted-T scar technique was used in 66.4%. Definitive findings of neither in-situ nor invasive cancer were identified in any of the cases. Conclusion: Despite major sequelae such as external permanent scarring and decrease in breastfeeding and nipple sensation, breast reduction surgery is the operation that records the highest patient satisfaction in plastic, reconstructive and aesthetica surgery, as it provides physical and psychological relief by eliminating the heavy weight that affects the shoulders, back and neck. It is also known that the risk of breast cancer is decreased due to the removal of a considerable amount of breast tissue with cancer potential from the body, as well as the early diagnosis and treatment of incidentally detected cancer cases, albeit at a low rate. This is also supported by our findings. [ABSTRACT FROM AUTHOR]

Purpose: We assessed the effects of COVID-19 infection on nasal mucociliary activity. Methods: The study was conducted in the pandemic wards of Adiyaman University Training and Research Hospital during April and May 2020. All patients admitted to the COVID-19 pandemic wards during the study period were invited to participate in the study. The study included 40 adults who agreed to participate and underwent a mucociliary clearance test successfully. The primary outcome was mucociliary clearance time and the secondary variables of interest were age, sex, and sino-nasal outcome test-22 scores. The control group included 40 concomitant healthy patients who visited the outpatient ear, nose and throat clinic with non-nasal symptoms. Results: The study included 40 COVID-19-positive patients and 40 healthy controls. The mean mucociliary clearance times of the study (15.53 ± 5.57 min) and control (9.50 ± 3.70 min) groups were significantly different (Z = 4.675, p < 0.001). However, the mucociliary clearance time was not significantly different between males and females (t = 0.590, p = 0.558). Conclusions: Nasal mucociliary clearance time was prolonged in COVID-19 patients compared to healthy controls. Thus, we conclude that smell and taste are crucial symptoms that should not be overlooked in patients suspected of COVID-19 disease. [ABSTRACT FROM AUTHOR]

In here, the nonisothermal decomposition kinetics of co-polymers based phenothiazine was present-ed. For this, firstly, 3, 7-di-2-thienyl-10H-phenothiazine (TF) was prepared via an optimized Suzu-ki--Miyaura cross-coupling reaction. After monomer (TF) characterization, the copolymerization re-actions with EDOT and thiophene were performed by the electrochemical technique. The molecular masses of the co-polymers were found by gel permeation chromatography (GPC) analysis. Thermal characterizations of the resulting polymers were conducted by thermogravimetric analyses. The thermal decomposition kinetics of the resulting polymers was also performed. For this, the kinetic methods (Tang, FWO, KAS, Kissinger, and Friedman) based on the multiple heating rates were used. Several kinetic parameters related to the decomposition kinetics of the solid-state were revealed. [ABSTRACT FROM AUTHOR]

Impedance spectroscopy techniques were used for analysis of the physical model in a two-phase system toward determining of dielectric constant of dielectric particles suspended in liquids at various solids loading (volume fraction) levels. Model experimental studies were conducted using BaTiO3 as a dielectric material that was prepared as small cubes of uniform size (2×2×1 mm). Barium titanate (BT) cubes having a dielectric constant of 3850 were immersed in liquids of low dielectric constant and moderate electrical conductivity. Measured impedance spectra consisted of two semicircles, which were fitted for (R∥C)(R∥C) equivalent circuit. The parameters obtained from fitting were compared with the data acquired from simulations of brick layer models and Maxwell-Wagner effective media model. In the investigated range of volume fractions the Maxwell-Wagner model correlates well with the data extracted from measurements. [ABSTRACT FROM AUTHOR]

Electrical characterization of slurries prepared by mixing dielectric powders with solvents can be used to estimate dielectric properties of the particles. In particular, dielectric constant of the particles can be calculated from effective dielectric constant of the slurry measured at high frequency by using the Lorentz-Lorenz or similar equations based on mixing rules. Unfortunately, this approach leads to high margin of errors in dielectric constant estimation and is very sensitive to any slurry nonidealities such as sedimentation or agglomeration of particles. Impedance spectroscopy techniques are introduced to measure dielectric properties of particles at different frequency ranges. Dielectric constant of strontium titanate particles, suspended in butoxyethanol, was determined reproducibly by impedance spectroscopy using an appropriate equivalent circuit model. [ABSTRACT FROM AUTHOR]

Introduction: Considerable advances have been made in hospital appointment systems in the past 60 years. In Turkey, the Central Physician Appointment System (CPAS) is used together with appointments made through direct presentations to the hospital. This study evaluated CPAS data. Materials and Methods: CPAS data for the previous 2 years (2015, Group 1; 2016, Group 2) were evaluated retrospectively. Department-based analysis was also performed. Total number of clinics, CPAS capacity, number of appointments through CPAS, and numbers of patients keeping appointments and 'no shows' and ratios calculated from these were investigated. Results: Overall, 1,704,594 patients were examined in 20 departments during the 2-year period (January 1, 2015-December 31, 2016). Mean CPAS capacity per department was 12,831 ± 7,691 in Group 1 and 11,573 ± 6,849 in Group 2 (p = 0.588). Ratios of appointments made through CPAS to CPAS capacity were 0.7 in Group 1 and 0.84 in Group 2 (p = 0.009). The ratio of patients keeping appointments made through CPAS to the number of appointments made through CPAS was 0.772 in Group 1 and 0.775 in Group 2 (p = 0.831). The departments with the highest number of appointments made through CPAS to CPAS capacity were Neurosurgery in Group 1 (0.99) and Ophthalmology in Group 2 (0.99). The department with the lowest ratio was Infectious Disease and Clinical Microbiology in Group 1 (0.28) and Group 2 (0.45). Conclusions: The use of CPAS has increased. However, some CPAS vacancies remain unfilled, and some appointments are not kept. CPAS capacities must be adjusted in line with take-up rates through regular department-based analysis. [ABSTRACT FROM AUTHOR]

Firstly, the axis of a slant helix is found. Secondly, the theorem which characterizes a slant helix is proved in detail. The importance of this theorem is stemed from that it has been led to doing many papers about slant helices. [ABSTRACT FROM AUTHOR]

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