943 research outputs found
Platinum nanoparticles loaded carbon black: reduced graphene oxide hybrid platforms for label-free electrochemical DNA and oxidative DNA damage sensing
No full textCarbon black-based hybrid materials have attracted great attention in the design of electrochemical sensors due to their consistent electroanalytical properties. With this in mind, for the first time, we present the preparation of platinum nanoparticles loaded carbon black:reduced graphene oxide (PtNPs/CB:rGO) hybrid platforms for label-free electrochemical DNA and DNA damage sensing. Synthesis of different hybrids was performed via microwave-assisted reduction method for the impregnation of platinum nanoparticles efficiently. These materials were characterized with X-ray diffraction analysis (XRD), Raman spectroscopy, transmission emission spectroscopy (TEM) and subsequently they were used for pencil graphite electrode modification in order to improve the characteristics of the surface. Modified electrodes were firstly applied for fish sperm DNA (fsDNA) analysis. The effect of different ratios (wt.:wt. %) of CB and rGO was investigated and it was shown that the hybrid material with 50:50 ratio had better sensitivity with a low detection limit of 0.14 mg L−1 and a good linearity to fsDNA between 1 and 200 mg L−1 (n = 3) based on guanine (G) oxidation by using differential pulse voltammetry (DPV). In order to expand this comparison, PtNPs/CB and PtNPs/rGO modified electrodes were also incorporated. Furthermore, the electroanalytical response of the hybrid material modified electrode was investigated based on the oxidation of thymine (T). Later on, oxidative DNA damage detection in the presence of Cu(II)/H2O2 reagents and protection studies in the presence of ascorbic acid were performed successfully by using electrochemical impedance spectroscopy (EIS). The study pointed out the remarkable reproducibility and sensitivity of the CB-based modification for nanoparticle decoration
Dönüt Türünün İçsel Motivasyon, Performansa Yönelik Öz-Yeterlik ve Dönüte Yönelik Yarar Algısı Üzerine Etkisi
No full textThis study examines the effect of elaborated feedback and elaborated feedback provided with affective feedback in formative assessment on situational intrinsic motivation, perceived usefulness of feedback, and perceived self-efficacy for learning and performance. A quasi-experimental approach is sought, and static-group post-test design is used in the study. Participants were 74 university students enrolled in Research Methods in Education and Scientific Research Methods courses. Data were collected through Scientific Research Methods Achievement Test, Situational Intrinsic Motivation Scale, and Perceived Usefulness of Feedback Scale, and Performance-Oriented Self-Efficacy Scale. Situational Intrinsic Motivation Scale and Perceived Usefulness of Feedback Scale were used after adaptation into Turkish language. Total 84 freshmen students were participated in the adaptation study, and the model was tested with confirmatory factor analysis, and validity and reliability results were reported accordingly. Data analysis was conducted through Independent Sample t test, Mann-Whitney U test, Kruskal-Wallis H test. The findings indicated no statistically significant effect of feedback type, elaborated feedback and elaborated feedback given with affective feedback, and students’ prior knowledge on the situational intrinsic motivation, perceived usefulness of feedback and self-efficacy for performance.Bu tez çalışmasında üniversite öğrencilerine biçimlendirmeye dönük değerlendirmede sadece detaylı dönüt ve duyuşsal dönütle birlikte verilen detaylı dönütün öğrencilerin duruma yönelik içsel motivasyon, dönüte yönelik yarar ile öğrenme ve performansına yönelik öz-yeterlik algısı üzerine etkisi incelenmiştir. Araştırma yöntemi olarak zayıf (statik) kontrol gruplu sontest deseni kullanılmıştır. Çalışmaya “Eğitimde Araştırma Yöntemleri” ve “Bilimsel Araştırma Yöntemleri” dersini alan 74 üniversite öğrencisi katılmıştır. Kullanılan veri toplama araçları, Bilimsel Araştırma Yöntemleri Başarı Testi, Durumsal İçsel Motivasyon Ölçeği, Dönüte Yönelik Yarar Algısı ve Öğrenme ve Performansa Yönelik Öz-Yeterliği Ölçeğidir. Durumsal İçsel Motivasyon Ölçeği ve Dönüte Yönelik Yarar Algısı Ölçeği Türkçeye uyarlanma çalışması yapıldıktan sonra kullanılmıştır. Uyarlama çalışmasına 84 üniversite birinci sınıf öğrencisi katılmış ve doğrulayıcı faktör analizi ile model test edilerek geçerlik ve güvenirlik sonuçları raporlanmıştır. Verilerin analizi için bağımsız örneklem t testi, Mann-Whitney U analizi ve Kruskal-Wallis H analizi kullanılmıştır. Çalışma sonucunda dönüt türü (sadece detaylı dönüt ve duyuşsal dönütle birlikte verilen detaylı dönüt) ve öğrencilerin ön bilgi seviyesinin öğrencilerin duruma yönelik içsel motivasyon, dönüte yönelik yarar ile öğrenme ve performansına yönelik öz-yeterlik algısı puanlarında istatistiksel olarak anlamlı bir fark yaratmadığı görüşmüştür
All-carbon hybrids for high performance supercapacitors
No full textA hybrid nanostructure with partially reduced graphene oxide (rGO) and carbon nanofibers (CNFs) was fabricated and used as supercapacitor electrodes. A straightforward, environmentally friendly, and low-cost microwave-assisted reduction process was developed for the synthesis of rGO/CNF hybrid structures. The fabricated supercapacitor devices showed a specific capacitance of 95.3 F g−1 and a superior long-term cycling stability. A capacitance retention of more than 97% after 11 000 galvanostatic charge discharge cycles was obtained. These and other results reported in this paper indicate that high-rate, all-carbon, rGO/CNF hybrid nanostructures are highly promising supercapacitor electrode materials
Electrospun Nanotubular Titania and Polymeric Interfaces for High Energy Density Li-Ion Electrodes
No full textIn the current study, for the first time, electrospinning of nanotubular structures was developed for Li-ion battery high energy density applications. For this purpose, titania-based nanotubular materials were synthesized and characterized. Before electrospinning with PVDF to obtain a self-standing electrode, the nanotubes were modified to obtain the best charge-transferring structure. In the current study, for the first time, the effects of various thermal treatment temperatures and durations under an Ar-controlled atmosphere were investigated for Li+ diffusion. Electrochemical impedance spectroscopy, cyclic voltammograms, and galvanostatic intermittent titration technique showed that the fastest charge transfer kinetics belongs to the sample treated for 10 h. After optimization of electrospinning parameters, a fully nanotube-embedded fibrous structure was achieved and confirmed by scanning electron microscopy and transmission electron microscopy. The obtained flexible electrode was pressed at ambient and 80 °C to improve the fiber volume fraction. Finally, the galvanostatic charge/discharge tests for the electrospun electrode after 100 cycles illustrated that the hot-pressed sample showed the highest capacity. The polymeric network enabled the omission of metallic current collectors, thus increasing the energy density by 14%. The results of electrospun electrodes offer a promising structure for future high-energy applications
Titania-Based Freestanding Electronically Conductive Electrospun Anodes with Enhanced Performance for Li-Ion Batteries
No full textA conductive composite binder made of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) and polyethylene oxide is utilized in a freestanding electrospun anode, loaded with high amounts of TiO2 for Li-ion batteries (LIBs). This kind of conductive binder polymer which enhances the performance of the cell is used for the first time. To prove the superior characteristics of these PEDOT:PSS binder-based electrodes, the polyvinylidene fluoride-based fibrous anode was also prepared by electrospinning. The electrospinning condition was thoroughly investigated and optimized to reach a robust fully covered fibrous network. The performed electrochemical characterizations show that PEDOT:PSS is electrochemically active and leads to an increased gravimetric capacity up to about 302 mA h/g at 0.2 C. After 100 cycles, PEDOT:PSS-based anodes showed a stable cycling performance which is comparable with commercial titanate-based electrodes. The outstanding performance of the electrodes is attributed to the improved titania loading and the electronically conductive highly porous network which contributed to charge-transfer kinetics. This study shows the potential of PEDOT:PSS as a conductive binder for other active materials in LIBs and self-standing electrodes for lower resistance and higher specific capacity
Transport characteristics of a ZnMgO/ZnO hetero junction and the effect of temperature and Mg content
No full textSelf consistent solution of Schrödinger Poisson equations and some electronic properties of ZnMgO/ZnO hetero structures
No full textMetal-Salt Enhanced Grafting of Vinylpyridine and Vinylimidazole Monomer Combinations in Radiation Grafted Membranes for High-Temperature PEM Fuel Cells
No full textProton exchange membranes were prepared and characterized for utilization in high-temperature proton exchange membrane fuel cells, HT-PEMFCs. 1-vinylimidazole (1-VIm) and 4-vinylpyridine (4VP) monomers were simultaneously grafted onto pre-irradiated ETFE (ethylene-co-tetrafluoroethylene) films which were prepared using γ-rays with a dose of 100 kGy, as a robust substrate to prepare acid-base composite membranes. The grafting reaction was performed at 60 °C for 24 h followed by protonation via phosphoric acid doping in the subsequent step. The effect of adding ferrous salts as promoters in grafting was investigated by characterization of resultant membranes via thermal gravimetric analysis and mechanical tests. The fuel cell tests were conducted under different relative humidities (RHs) and applied temperatures. Membranes prepared with salt addition exhibited superior proton conductivities. Results including up to 80 mS cm-1 conductivity at 110 °C in 60% RH and excellent thermal stability, even at 300 °C, suggest these membranes are promising for HT-PEMFC applications
Impact of Having a Disabled Child on Mothers’ Anxiety, Depression and Quality of Life Levels
No full textPurpose: The aim of this study is to investigate the effects of the financial burdens, familial and social life, personal strain due to psychological burdens and stress coping behaviors on the anxiety, depression and quality of life of mothers with a disabled child. Materials and methods: Mothers ( =33.32±6.31 years) of 50 disabled children (x-±SD=7.66±3.96 years) included in the study and were evaluated with Impact on Family Scale (IFS), Hospital Anxiety and Depression Scale and Nottingham Health Profile. Results: A moderate correlation was found between the depression and anxiety levels of the mothers and all parameters except the coping (p0.05). A high degree correlation was found between quality of life of mothers and financial burden and familial and social impact, and a moderately positive correlation with personal strain and coping (p0.05). Also correlations were found between the sleep and all parameters of IFS (p0.05). IFS affects the anxiety and depression levels of the mothers (p0.05). Quality of life of mothers were affected by the IFS. Conclusion: Having a disabled child was inevitable for mothers to have problems in familial and social life. The psychological and physical loads cause mothers to experience personal difficulties and imbalances, and have also affected their depression and anxiety levels. © 2021, Pamukkale University. All rights reserved
Experimental and Numerical Investigation of Flow Over Ogee Spillway
No full textOgee type spillway is one of the most preferred sluice types due to its functional suitability and high safety factor. It is used for controlling the flow rates and water levels in reservoirs, such as lowering the water level in emergency situations, maintaining normal river functions and discharging excess water. The main aim of this study is to investigate the flow over ogee type spillway by performing experiments in an open channel flume in the laboratory and simulating with numerical model. The numerical model having the same dimensions with the physical model is modeled with two different programs of ANSYS-Fluent and OpenFOAM. The flow depths of the models were measured at four points, H-1, H-2, H-3, H-4. In the numerical analysis, two different turbulence models, K-epsilon and K-omega SST turbulence model were used in order to investigate the accuracy of the turbulence models in the open channel. According to the results, R(2)values, obtained from ANSYS- Fluent for the each measurement points where H-1, H-2, H-3, H-4, are 0.9776, 0.9859, 0.9701, 0.9916 and obtained from OpenFOAM for the each measurement points 0.9920, 0.9687, 0.9855, 0.9926 respectively. The findings show that the numerical tools have been sufficiently developed to simulate flow depths and water surface profiles
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