215 research outputs found
The effect of anisotropy on residual stress values and modification of Serruys approach to residual stress calculations for coatings such as TiN, ZrN and HfN
No full textThe residual stresses in literature on hard coatings (e.g., TiN, CrN, HfN and ZrN) are usually calculated using the mechanical elastic constants often determined by indentation technique by assuming isotropic behavior. The effect of anisotropy of the hard coatings on residual stress values such as TiN, ZrN and HfN has been documented using classical technique and Thin Film techniques (fixed incidence multiplane (FIM) Technique). Due to lack of the single crystal data, the anisotropy of coatings has been taken into account through XECs determined experimentally for ZrN, HfN and TiN films. Recently, single crystal elastic constants of the ZrN, HfN and NbN have been measured. In the light of single crystal elastic constant data, residual stresses reported in the literature were reevaluated according to Reuss, Voigt, Hill (or mixed) and Kroner models using the best fitting approach after modifying Serruys approach. The modified Serruys approach captures the anisotropic behavior of coatings such as ZrN and Zr(Hf)N. The residual stress calculations were improved and the residual stress values were significantly increased as high as 30% compared to the previously published data. The best fitting approach (modified Serruys approach) was compared to the procedure used by Perry using experimentally determined XECs. (c) 2006 Elsevier B.V. All rights reserved
Three-dimensional ultrasonographic demonstration of agenesis of the 12th rib in a fetus with trisomy 21
No full textKinetics and mechanisms of biosorption of copper ion onto waste yeast (S. cerevisiae)
No full textSpringer NetherlandsHeavy metals are the most common pollutants found in industrial effluents. Several chemical treatment methods are used to remove heavy metals from aquatic solutions. Recently, biosorption process which utilizes various microbial materials (bacteria, fungi, yeasts, algae etc.) has been preferred to remove pollutants. In this study, waste yeast taken from yeast factory in Turkey was used as (working volume of 100 ml) biosorbent in erlenmeyer batch experiments by using temperature controlled shaker and copper (II) ion biosorption was examined. The effects of initial pH (2, 3, 4, 5, 6, 7), initial copper concentrations (25, 50, 75, 100, 150, 200, 250, 300 mg L?1), biosorbent amount (1, 3, 5, 7 10 g L?1), contact time (5, 10, 15, 30, 45, 60, 90, 120, 240, 1440 min.) and temperature (20, 30, 40, 50 °C) parameters on to biosorption process were investigated. Optimum biosorption capacity was found as pH 5, 100 mg L?1 of initial copper concentration, 10 g L?1 biosorbent amount and 1440 min. of contact time. The experimental equilibrium data fitted to Freundlich and Langmuir adsorption isotherm models. Freundlich models fitted better than Langmuir models. The maximum adsorption capacity of waste yeast was determined as 7.94 mg g?1and Freundlich isotherm values n and kf were found to be 1.55 and 0.21 respectively. Pseudo-second order kinetic model was suitable for biosorption kinetics. According to calculated thermodynamic parameters (?H, ?G and ?S), biosorption of copper onto waste yeast was exothermic. As a conclusion; it was found that copper (II) removal by using waste yeast was low. Activation of biomaterial by pretreatment can be resulted in increasing of removal rate. Use of waste materials in pollution control is important for economic issue. © Springer Science+Business Media Dordrecht 2015.Sarioglu Cebeci, M.; Cumhuriyet University, Department of Environmental EngineeringTurkey; email: [email protected]
Supersymmetric solutions of N = (1,1) general massive supergravity
No full textWe construct supersymmetric solutions of three-dimensional N = (1, 1) general massive supergravity (GMG). Solutions with a null Killing vector are, in general, pp-waves. We identify those that appear at critical points of the model, some of which do not exist in N = (1, 1) new massive supergravity (NMG). In the timelike case, we find that many solutions are common with NMG, but there is a new class that is genuine to GMG, two members of which are stationary Lifshitz and timelike squashed AdS spacetimes. We also show that in addition to the fully supersymmetric AdS vacuum, there is a second AdS background with a nonzero vector field that preserves 1/4 supersymmetry
Removal of ammonium from municipal wastewater using natural Turkish (Dogantepe) zeolite
No full textThis paper concerns the removal of ammonium ions from wastewater using a naturally occurring zeolite from Dogantepe region in Turkey. Both batch and continuous (column) experiments were carried out. In batch studies, effects of stirring time (5-120 min) and initial ammonium concentration (8.8-885 mg NH4+-N l-1) on removal efficiency and adsorption isotherms were investigated. In column studies, effects of flowrate, pH, initial ammonium concentration, washing with acid and regeneration on the ammonium adsorption capacity of the zeolite were determined. Increasing initial ammonium nitrogen concentration from 5.0 to 12.0 mg l-1, increased the exchange capacity from 0.70 to 1.08 mg NH4+-N g-1. The flowrate and pH values, at which the highest adsorption capacities were obtained, were found to be 0.5 ml min-1 (0.87 mg NH4+-N g-1 zeolite) and 4 (mg NH4-N l-1), respectively. The corresponding values after washing with acid and regeneration were determined to be 1.32 and 0.73 mg NH4+-N g-1, respectively. The cation exchange capacity of Dogantepe zeolite was found to be 164.62 meq. per 100 g. These findings show that Dogantepe zeolite can be used for the removal of ammonium from wastewater. © 2004 Elsevier B.V. All rights reserved
Fast and low-cost fabrication of 1D hematite photoanode in pure water vapor and air atmosphere: Investigation the effect of the oxidation atmosphere on the PEC performance of the hematite photoanodes
No full textIn this study, hematite photoanodes were successfully fabricated by thermal oxidation of the commercial cold-rolled steel at 500 degrees C in pure water vapor and air atmosphere. The crystal phase structure, surface morphology, and optical properties of the hematite photoanodes were characterized using an X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM) and UV-VIS spectrophotometer, respectively. The results showed that hematite photoanodes had high crystalline phase and the annealing atmosphere influenced the morphology of the hematite photoanodes. Moreover, nanowhisker and nanorod shaped nanostructures were observed on the substrate. The optical band gap values of the hematite photoanodes varied between 2.38 and 2.70 eV. Photoelectrochemical (PEC) studies of the hematite photoanodes were assessed in the 0.1 M NaOH electrolyte solution using the Mott-Schottky analysis and electrochemical impedance spectroscopy techniques. The PEC findings exhibited that the hematite photoanode annealed 15-min in water vapor had best PEC performance achieving photocurrent density 0.244 mA/cm(2) at 1.6 V vs. V-RHE and highest carrier density value (N-D = 1.15 x 10(21) cm(-3)). Furthermore, the photoanodes annealed in water vapor atmosphere revealed at least three times higher PEC performance than that of photoanodes annealed in air. Thermal oxidation method in water vapor is an efficient methods for fabrication of hematite photoanodes. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved
Residual stresses in (Zr,Hf)N films (up to 11.9 at.% Hf) measured by X-ray diffraction using experimentally calculated XECs
No full textIn the present work, the residual stresses of (Zr,Hf)N films were measured using X-ray diffraction (XRD) fixed incident multiplane technique (FIM) for varying amounts of Hf addition by assuming the film was isotropic and anisotropic (Kronel model). The residual stress values calculated according to isotropic and anisotropic models were almost the same (-6 GPa). Addition up to 11.9 at.% Hf into ZrN films did not affect the level of residual stress. (C) 2004 Elsevier B.V. All rights reserved
Effects of chronic L-DOPA administration on neurogenic and endothelium-dependent relaxation responses in rabbit corpus cavernosum
No full textSARIOGLU, YUSUF/0000-0002-9227-365X; Yildirim, seniz/0000-0001-8038-5796Background: Dopamine is a crucial central neurotransmitter that plays a fundamental role in the autonomic and somatic components of penile reflexes in animals and humans. Similar to the erectile responses of dopamine, systemic administration of L-DOPA induces yawning and penile erection in some species. The possible effects of L-DOPA on nitric oxide (NO)-dependent and-independent non-adrenergic non-cholinergic (NANC) relaxation responses mediated by electrical field stimulation (EFS) and endothelium-dependent relaxation were investigated in this study. Methods: Thirty-two adult albino male rabbits, in two- and four-week-treatment groups, were divided into three subgroups: control group (saline-injected) (n = 4), 3 mg/kg/day (low dose) L-DOPA-injected groups (n = 6) and 12 mg/kg/day (high dose) L-DOPA-injected groups (n = 6). After the intraperitoneal injection treatments, the corpus cavernosum tissues were placed in organ bath chambers. The EFS-mediated responses, and the concentration-response curve to carbachol, sodium nitroprusside (SNP), sildenafil were assessed. Results: The two-week treatment with high-dose L-DOPA decreased the NO-dependent NANC relaxation responses, while there was no change in the low-dose two- and four-week treatment groups. The NO independent NANC relaxation responses in the two-week groups decreased, and the responses in the four-week groups were unchanged when compared to the controls. The relaxation responses to carbachol showed no differences among all groups except for the high-dose four-week L-DOPA group. The relaxation responses of SNP and sildenafil were increased in all of the treatment groups when compared to the controls. Conclusions: The observed increases in SNP- and sildenafil-induced responses, along with the decreased EFS-mediated responses, suggest increased sensitivity in the NO-signalling pathway following L-DOPA administration. (C) 2016 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Sp. z o.o. All rights reserved
Suppersymmetric strings and waves in D=3, N=2 matter coupled gauged supergravities
No full textWe construct new 1/2 supersymmetric solutions in D = 3, N = 2, matter coupled, U(1) gauged supergravities and study some of their properties. In the most general case they represent a string superposed with gravitational and Chern-Simons electromagnetic waves. The waves are attached to the string and the solution satisfied an electromagnetic self-duality relation. When the sigma model is non-compact it interpolates between as asymptotically Kaigorodov space and a naked singularity. For the compact sigma model there is a regular horizon with the Kaigorodov geometry and asymptotically it is either Minkowskian or a pp-wave. When the sigma manifold is flat our solutions describe either AdS(3) or Kaigorodov space of a pp-wave in AdS(3)
Suppersymmetric strings and waves in D=3, N=2 matter coupled gauged supergravities
No full textWe construct new 1/2 supersymmetric solutions in D = 3, N = 2, matter coupled, U(1) gauged supergravities and study some of their properties. In the most general case they represent a string superposed with gravitational and Chern-Simons electromagnetic waves. The waves are attached to the string and the solution satisfied an electromagnetic self-duality relation. When the sigma model is non-compact it interpolates between as asymptotically Kaigorodov space and a naked singularity. For the compact sigma model there is a regular horizon with the Kaigorodov geometry and asymptotically it is either Minkowskian or a pp-wave. When the sigma manifold is flat our solutions describe either AdS(3) or Kaigorodov space of a pp-wave in AdS(3)
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