5,507 research outputs found
Structural and ESR studies of Cu‐doped ZnO nanostructures
No full textSurface morphology, structural phases, and electron spin resonance (ESR) measurements were performed for Zn1-xCuxO nanoparticles (x = 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05) synthesized by sol-gel method. The optimum annealing temperature (600 degrees C) and weight loss was clarified using differential thermal analysis (DTA), and thermo gravimetric analysis (TG). By means of X-ray diffraction (XRD) technique, the phase of the samples was defined as single with ZnO wurtzite hexagonal structure and proofed by Rietveld analysis for Zn0.98Cu0.02O sample with calculating c/a rate. Spherical shape random particle distributions were observed in all scanning electron microscope (SEM) measurements. ESR measurements were conducted for all samples and g-value and Delta H (G) values were calculated and correlated from ESR measurements
New generation radiation-grafted PVDF-g-VBC based dual-fiber electrospun anion exchange membranes
No full textAnion Exchange Membranes (AEM) have the potential to solve the cost issues of fuel cell technologies due to their basic environment that can allow the use of cheaper components. However, there is still a need to develop an ideal inexpensive, mechanically robust AEM with high ionic conductivity and ion exchange capacity (IEC). In this work, we present various dual-fiber electrospun membranes based on a novel radiation-grafted copolymer. First, the synthesis route of radiation-induced grafting of vinyl benzyl chloride (VBC) onto poly (vinylidene fluoride) (PVDF) to prepare PVDF-g-VBC was optimized. Then, PVDF-g-VBC powders were used to fabricate dual-fiber electrospun mats with inert PVDF and commercial Fumion-FAA-3 ionomer. Dual-fiber electrospun mats were hot-pressed and then quaternized with trimethylamine. Finally, mechanical properties, ion exchange capacity, ionic conductivity, and morphology of these prepared dual-fiber electrospun membranes were investigated. The dual-fiber membrane prepared with PVDF-g-VBC (88% of the total weight of the membrane) and PVDF: Fumion-FAA-3 (1:2) mix (12 wt%) realized ionic conductivity of 4.67 mS/cm at 25 °C, high ion exchange capacity of 1.35 mmol/g with Young's Modulus of 761 MPa. The membrane based on the combination of radiation grafting and dual-fiber electrospinning was prepared for the first time in literature and offers the prospect of tuning and fine-control of mechanical and physicochemical properties of AEMs
A necessary condition for generic rigidity of bar-and-joint frameworks in -space
No full textA graph is -sparse if each subset with induces at most edges in . Maxwell showed in
1864 that a necessary condition for a generic bar-and-joint framework with at
least vertices to be rigid in is that should have a
-sparse subgraph with edges. This necessary
condition is also sufficient when but not when . Cheng and
Sitharam strengthened Maxwell's condition by showing that every maximal
-sparse subgraph of should have edges when
. We extend their result to all .Comment: There was an error in the proof of Theorem 3.3(b) in version 1 of
this paper. A weaker statement was proved in version 2 and then used to
derive the main result Theorem 4.1 when . The proof technique was
subsequently refined in collaboration with Hakan Guler to extend this result
to all in Theorem 3.3 of version
Reaching Rigor for English Learners Through Responsive Interactions of Care
No full textCitation: Holmes, M., Kavimandan, S., & Herrera, S. (2018). Reaching rigor for English learners through responsive interactions of care. In N. Guler (Ed.), Optimizing elementary education for English language learners (pp. 91-115). Hershey, PA: IGI Global.This chapter explores what happens when teacher-student and student-student interactions reflect a higher level of responsiveness to the human beings involved. It describes biography-driven instruction (BDI), a research-based method of instruction that supports all learners to reach high academic standards, while at the same time ensuring that English learners have the scaffolds and tools needed to engage fully in the curriculum. Teachers who implement BDI develop a holistic understanding of students' sociocultural, linguistic, cognitive, and academic dimensions. They use students' background knowledge as a springboard to new learning. To determine the impact of BDI on the education of English learners in elementary classrooms, this chapter explores the perspectives of 16 teachers (Grades 1-6) who received professional development on BDI and then implemented the method with their own communities of learners. Interview data was collected in Spring 2016, transcribed, and qualitatively analyzed. Findings in the form of themes in participant voice are discussed throughout the chapter
HPLC-DAD profiles and pharmacological insights of Onobrychis argyrea subsp isaurica extracts
No full textOnobrychis argyrea Boiss. subsp. Isaurica (Fabaceae), endemic to the eastern Mediterranean region, is a poorly studied medicinal plant. This study sets out to investigate into antioxidant and inhibitory activities of O. argyrea extracts (ethyl acetate, methanol, and water) against key enzymes linked to diabetes (α-amylase, α-glucosidase), Alzheimer's disease (acetylcholinesterase, butyrylcholinesterase), and skin hyperpigmentation (tyrosinase). Phytochemical composition was determined by HPLC-DAD and in silico approach used to provide additional insight of the possible interaction of the identified phenolic compounds with the studied enzymes. The methanol extract showed potent inhibitory action against acetylcholinesterase (1.55 mg GALAE/g extract), tyrosinase (61.61 mg KAE/g extract), and glucosidase (20.17 mmol ACAE/g extract). The methanol extract of O. argyrea exhibited potent radical scavenging potential (126.51 mg TE/g extract for DPPH scavenging assay) and reducing capacities (311.36 and 200.70 mg TE/g extract, for CUPRAC and FRAP assays, respectively). Quercetin, apigenin, and benzoic acid were identified in significant amounts in the methanol extract of O. argyrea. Quercetin interacted with the catalytic pocket of glucosidase by establishing hydrogen bonds with Ser157, Ser241, Asp307, and π-π interactions with His280 and Tyr158. The observed inhibitory effects of O. argyrea extracts on the studied enzyme suggest that this plant could be a promising source of naturally occurring chemical compounds for the management of diabetes, Alzheimer's disease, skin hyperpigmentation disorders, as well as, oxidative stress-related complications
A COMPARATIVE ANALYSIS OF GAME THEORY MODELS FOR ASSESSING THE PERFORMANCES OF NETWORK CONSTRAINED ELECTRICITY MARKETS
No full textGraphene assisted template based LiMn2O4 flexible cathode electrodes
No full textIn this paper, a systematic method has been developed to produce highly flexible and robust graphene/LiMn2O4 (G/LCMO) and graphene/LiCr0.05Mn1.95O4 (G/LMO) free-standing composite cathode electrodes with increased specific capacity and improved electrochemical capability. Spinel LMO nanorods are synthesized by calcination method followed by a hydrothermal reaction technique. As-synthesized nanorods were then embedded in a graphene layer which will in turn serve as a self-standing binder-free cathode electrode. Spinel LMO and LCMO nanorods with a length of 600 nm and width of 50 nm were then homogenously entrapped and distributed within the layers of conductive graphene structure. This hybrid structure will help to eliminate the use of heavy metal current collectors and electrically resistant binders or even conductive additives. A discharge capacity of 114.5 mAh g(-1) is obtained after first cycle and %72 capacity retention is obtained after 250 cycles from G/LCMO freestanding samples. The enhancement in the electrochemical properties is due to the unique freestanding structure of the cathode electrodes
Single and binary biosorption of Cu(II), Ni(II) and methylene blue by raw and pretreated Spirogyra sp.: Equilibrium and kinetic modeling
No full textThe raw and pretreated Spirogyra sp. were used for the single and binary removal of Cu(II), Ni(II) and methylene blue (MB) from aqueous solution. The effects of pH, contact time, initial pollutant concentration, biosorbent dosage and ionic strength (NaCl) on removal efficiency were investigated. The biosorption capacity of Cu(II), Ni(II) and MB onto raw and pretreated Spirogyra sp. was found as the following order: MB > Cu > Ni and Ni > MB > Cu. The pseudo-first order, pseudo-second order and the intraparticle diffusion models were applied to the experimental data. The thermodynamic parameters (?H, ?S, ?G) were calculated. Desorption studies was also done. The structural characteristics of biosorbent were determined through FT-IR spectrums and SEM images. Also, binary biosorption studies showed that removal efficiency of dominant pollutant reduced by the presence of the other ion in aqueous solution. © 2013 Elsevier Ltd. All rights reserved.M-326This work is supported by the Scientific Research Project Fund of Cumhuriyet University under the project number M-326.Guler, U.A.; Department of Environmental Engineering, Engineering Faculty, Cumhuriyet University, Sivas 58140, Turkey; email: [email protected]
A fixed point theorem on soft G-metric spaces
No full textWe introduce soft G-metric spaces via soft element. Then, we obtain soft convergence and soft continuity by using soft G-metric. Also, we prove a fixed point theorem for mappings satisfying sufficient conditions in soft G-metric spaces. © 2016 All rightsEge University, Department of Mathematics, İzmir, 35100, Turkey; Yaşar University, Department of Mathematics, İzmir, 35100, Turke
Carbon-silicon composite anode electrodes modified with MWCNT for high energy battery applications
No full textIn this study, we comparatively study the electrochemical characteristics of Si, Si-C and vacuum-assisted filtration fabrication of a novel free-standing Si@C/Mutli Wall Carbon Nanotubes (MWCNT) nanocomposite. The surfaces of the as-received Si nanaoparticles were coated with an amorphous carbon layer and homogenously anchored onto the surfaces of as-received MWCNTs by a simple vacuum filtration method. The samples were then analyzed with field emission scanning electron microscopy and X-ray diffraction (XRD) methods. Si@C/MWCNT samples have shown a stable capacity of 1290 mA h g(-1) after 200 cycles. The results have proven that MWCNT's large surface area, highly conductive network which can provide good contact between Si@C nanoparticles, tolerating large volume change sand suppressing aggregation of Si@C nanoparticles during charge/discharge processes. Such a comparison between the performances of carbon-MWCNT-metal materials is reasonably envisaged not only to be useful for understanding the individual contribution from MWCNT and metal but also to form a fundamental basis for energy storage applications. Free-standing Si-C/MWCNT nano paper has been successfully obtained by a facile vacuum filtration method. (C) 2018 Elsevier B.V. All rights reserved
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