 Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
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- Electrochemical Properties of Low Bi Doped La0.60Dy0.10Sr0.30Mn(1-x)BixO3
Perovskite Materials
Authors: Mustafa Zeki KURT
Abstract: Developing low-cost, high-durability and high-performance electrocatalytic materials are needed for hydrogen/oxygen evolution (HER/OER) and oxygen reduction reactions (ORR) which are crucial steps for regenerative fuel cells. Although Pt-based, RuO2 and IrO2 materials are widely used for these purposes, other alternative materials are required with desired properties. In this regard, we studied the electrochemical properties of lanthanum-based perovskites which were synthesized by sol-gel method. We investigated the substitution of 10% Dy and 30% Sr into the A site and a small amount of Bi (x: 0, 0.03 and 0.1) added into the B site of La0.60Dy0.10Sr0.30Mn(1-x)BixO3 perovskites on HER, OER and ORR in 1 M KOH alkaline media at room temperature. While undoped and 3% Bi doped samples exhibited poor HER activities, the effect of 10% Bi in the structure enhanced HER activities by lowering onset potential from -1.389 V to -1.036 V (vs. Ag/AgCl) and increasing specific current density from -13.3 mA cm-2 to -121.8 mA cm-2 at -1.4 V. Similarly, OER activity was also improved due to 10% Bi and onset potential and specific current density was found to be 0.758 V and 88.3 mA cm-2, respectively. The large Tafel slopes indicate that the ORR mechanism is possible in the structure but at a slow rate. The addition of 10% Bi in the structure resulted in a very high resistance of 19.3 kΩ and it reduced to a desired value of 3.5 kΩ due to ion conducting paths developed in the catalysts.
PubDate: Fri, 30 Dec 2022 00:00:00 +030
- Determination of Some Elements in Canned and Frozen Vegetables Sold in
Balıkesir (Türkiye) Markets and Nutritional Assessment
Authors: Feyzullah TOKAY
Abstract: In this work, determination of some elements including Pb, Ni, Ba, Fe, Zn, Mg, Mn, Al, Cu, Mo, Ca, B, Cr, Cd, V and Co was carried out in some canned and frozen vegetable samples sold in Balıkesir, Türkiye. The study covered randomly chosen 13 canned and frozen samples such as green peas, okra, shell bean, sweet corn, green beans, garniture and tomato paste. Mineralization of the samples was achieved using microwave assisted wet digestion in closed vessels. The element contents were determined using ICP OES. The element contents were between 0.16-1.86 mg kg-1 for Ni; 0.33-5.02 mg kg-1 for Ba; 4.20-32.22 mg kg-1 for Fe; 1.65-14.64 mg kg-1 for Zn; 124.83-1016.79 mg kg-1 for Mg; 0.87-4.99 mg kg-1 for Mn; 0.32-1.74 mg kg-1 for Al; 0.78-14.97 mg kg-1 for Cu; 0.38-4.24 mg kg-1 for Mo; 42.60-1607.40 mg kg-1 for Ca and 0.96-7.56 mg kg-1 for B. Additionally, Pb was determined in only frozen green peas as 1.3±0.1 mg kg-1. In general, the highest element contents were found in frozen samples. In terms of nutritional assessment, estimated daily intakes of the elements were compared with recommended dietary allowances (RDA), nutrition reference values (TFC) and daily tolerable upper intake levels (UL) which were established by World Health Organization, Turkish Food Codex and Institute of Medicine, respectively. The results showed that the element contents of the analysed samples did not exceeded the permissible limits set by various health organizations. It is concluded that the contamination of these products may be an important threatening for public health. Therefore, monitoring of these samples should be a vital strategy for food industry.
PubDate: Fri, 30 Dec 2022 00:00:00 +030
- Redescription of Penicillicaris pectinimana (Car, 1884) (Copepoda,
Harpacticoida, Parastenheliidae)
Authors: Seher KURU; Süphan KARAYTUĞ
Abstract: The main aim of this study is to conduct a taxonomic revision of Penicillicaris pectinimana living in the mediolittoral zone of Türkiye. Therefore, numerous specimens of both sexes collected from Mediterranean (25 localities), Aegean (9 localities) and the Black Sea (10 localities) coasts were morphologically reexamined in detail for the first time with the aid of light and scanning electron microscopes. Hundreds of individuals belonging to Penicillicaris pectinimana populations collected from different localities were comparatively analysed in terms of inter/intra population variability. In the light of the data obtained in this study, it was revealed that Penicillicaris pectinimana has very wide distribution on the coasts of Turkey and it is found in all localities examined. All possible morphological details of both sexes of Penicillicaris pectinimana were redescribed for the first time in detail since it was described in 1884.
PubDate: Fri, 30 Dec 2022 00:00:00 +030
- Wave Solution Analysis of a Nonlinear Mathematical Model on Fluid
Mechanics
Authors: Tolga AKTÜRK; Volkan ÇAKMAK
Abstract: This study obtains some wave solutions of the B-type Kadomtsev Petviashvili equation by applying the modified exponential function method (MEFM). Thanks to this method, the exact solutions of the non-linear partial differential equations will be obtained and there will be an opportunity to examine the physical structure of these solutions. Due to the nature of MEFM, two different cases are presented here that have been analyzed to obtain more solutions in this structure. More wave solutions can be obtained by analyzing different situations. When the resulting solutions are analyzed, hyperbolic, trigonometric, and rational functions are observed. It has been checked whether the solution functions found with Wolfram Mathematica software provide the B type Kadomtsev Petviashvili equation and graphs simulating the wave solution behavior with the determined appropriate parameters are presented.
PubDate: Fri, 30 Dec 2022 00:00:00 +030
- Blending of Poly(methyl methacrylate) with
Poly(1,3-diphenyl-1H-pyrazol-5-yl methacrylate): Investigation of its
Optical Properties
Authors: Adnan KURT; Murat KOCA
Abstract: In the present study, a new blend polymer consisting of a pyrazole-derived polymer poly(1,3-diphenyl-1H-pyrazol-5-yl methacrylate) and poly(methyl methacrylate) was prepared with solution mixing method. The blend polymer was spectrally characterized with FTIR and 1H- NMR techniques. TGA analysis showed that the blend polymer was stable up to 275.4 °C. A thin film of blend polymer was prepared by using spin coating technique. The UV measurements were obtained as a function of wavelength (300 – 700 nm). The optical and dispersion parameters were reported in detail. Transmittance was increased depending on the increasing wavelength whereas the reflectance decreased. The Transmittance value at 700 nm was measured as 97.55%, meaning the blend polymer was transparent. The refractive index at 700 nm was 1.37. The Urbach energy (Eu) and the optical band gap constant (Eg) were calculated to be 0.831 eV and 3.737 eV, respectively. The type of electronic transitions for polymer was determined as indirect allowed transition.
PubDate: Fri, 30 Dec 2022 00:00:00 +030
- Computational Investigation of
5.5'',7''-trihydroxy-3,7-dimethoxy-4'-4'''-O-biflavone from Flavonoids
Using DFT Calculations and Molecular Docking
Authors: Mehmet BAĞLAN; Ümit YILDIKO, Kenan GÖREN
Abstract: The structural characterization of the 5.5",7"-trihydroxy-3,7-dimethoxy-4'-4'''-O-biflavone (TDOB) molecule was done in this study. For the structural characterization of this molecule, based on the molecule's stable phase geometry, entire calculations were done using the CAM-B3LYP and PBEPBE approaches with SDD and LanL2DZ basis sets respectively. In our study, many calculations, such as HOMO-LUMO energy gaps, inter-orbital, and inter-orbital bond interactions, and electrostatic surface mapping processes of the TDOB molecule, have also been made. In the continuation of our study, the specific binding site and mechanism of the ligand on the protein were investigated using molecular docking. In the molecular docking study, affinity scores for TDOB- aldose reductase (PDB: 4ICC) and (PDB: 4IGS) were found to be -8.559 kcal/mol and -5.461 kcal/mol, respectively. The 4ICC receptor binding score was found to be greater. In the continuation of the molecular docking study, the inhibitory properties of TDOB were investigated against the aldose reductase enzymes (PDB: 4ICC) and (PDB: 4IGS), both of which showed effective inhibition, and it was seen that the TDOB molecule effectively inhibited the enzymes (PDB: 4ICC) and aldose reductase (PDB: 4IGS).
PubDate: Fri, 30 Dec 2022 00:00:00 +030
- Parameter Estimation Procedures for Log Exponential-Power Distribution
with Real Data Applications
Authors: Mustafa Ç. KORKMAZ; Kadir KARAKAYA, Yunus AKDOĞAN
Abstract: In this study, some estimation techniques are investigated to estimate two parameters of the log exponential-power distribution. The maximum likelihood, quantile, least squares, weighted least squares, Anderson-Darling, and Cramer-von Mises estimation methods are studied in detail. The efficiency of these estimators is validated through Monte Carlo simulation experiments. Also, four real data applications are performed and Kolmogorov-Smirnov statistic results for all estimators are presented.
PubDate: Fri, 30 Dec 2022 00:00:00 +030
- An Application of Trigonometric Quintic B-Spline Collocation Method for
Sawada-Kotera Equation
Authors: Hatice KARABENLİ; Alaattin ESEN, Murat YAĞMURLU
Abstract: In this paper, we deal with the numerical solution of Sawada-Kotera (SK) equation classified as the type of fifth order Korteweg-de Vries (gfKdV) equation. In the first step of our study consisting of several steps, nonlinear model problem is split into the system with the coupled new equations by using the transformation w_xxx=v. In the second step, to get rid of the nonlinearity of the problem, Rubin-Graves type linearization is used. After these applications, the approximate solutions are obtained by using the trigonometric quintic B-Spline collocation method. The efficiency and accuracy of the present method is demonstrated with the tables and graphs. As it is seen in the tables given with the error norms L_2 and L_∞ for different time and space steps, the present method is more accurate for the larger element numbers and smaller time steps.
PubDate: Fri, 30 Dec 2022 00:00:00 +030
- Investigation of Apoptotic Effect of Klotho Protein on Human Colorectal
Cancer Cells via TRAIL Death Receptors
Authors: Sibel GUNES; Onur UYSAL, Merve Nur SOYKAN, Ayla EKER SARIBOYACI
Abstract: Klotho is a transmembrane protein which is deficiency has pleiotropic effects in a number of aging-related disease processes and various cancers. In some recent studies about klotho protein disorders, it has been shown to klotho is effective in various cancers including lung, liver, breast, kidney, and colon. TNF-related apoptosis-inducing ligand (TRAIL), a TNF family molecule, is a cytokine that stimulates apoptosis through death receptors in many cancer types and therefore attracts attention for tumor therapies in various preclinical models. Interaction with TRAIL death receptors create an apoptotic effect in cancer treatments by reducing the proliferation of cancer cells. In this study, it was aimed to investigate the effects of exogen klotho administration on cell viability and apoptosis on TRAIL death receptors (TRAIL1 and TRAILR2) in human healthy colon cells (CCD 841 CoN) and TRAIL-resistant human colorectal cancer cells (caco2). For this purpose, cells were treated with different concentrations of klotho for 24 and 48 hours. To determine the cell viability, proliferation, and death receptors effects of klotho protein on cancer and healthy cells evaluations with WST-8 and Real-Time qRT-PCR analysis were performed. Our results showed that the increase in klotho protein concentration did not have a significant effect on cell viability in healthy colon cells, whereas it decreased cell viability and proliferation in apoptosis-resistant human colorectal cancer cells. Relative gene expression of TRAIL1 and TRAILR2 death receptors increased with klotho applied to the apoptosis-resistant colorectal cancer cell line caco-2. Therefore, targeting the ligand-receptors that induce TNF-related apoptosis with the klotho protein can be considered as a potential therapeutic approach for cancer therapy.
PubDate: Fri, 30 Dec 2022 00:00:00 +030
- Contributions to the Flora of Çelikhan District (Adıyaman)
Authors: Ömer KILIÇ; Sinasi YİLDİRİMLİ
Abstract: This study was carried out to contribute to the flora of Çelikhan District (Adıyaman). 592 plant samples were collected from the research area. As a result of the evaluation of these plants, a total of 454 taxa were identified, including 295 genera belonging to 62 families. Of these taxa, 3 of them were belong to Pteridophyta and 451 of Spermatophyta divisions. Coniferophyta and Magnoliophyta subdivisions in the Spermatophyta division contained 2 and 449 taxa, respectively. It was determined that 449 taxa were belong to Magnoliophyta subdivision, 385 were belong to Magnoliopsida and 64 were belong to Liliopsida class. It was determined that 30 taxa from the study area were endemic, and the endemism rate was found to be 6.6%. The distribution of taxa according to phytogeographic regions were as follows: Anatolian-Turan 158 (34.8%), Mediterranean 34 (7.5%), Euro-Siberian 33 (7.1%), multi-regional and unknown phytogeographical regions 229 (50.4%). The first five family according to the number of taxa were; Asteraceae 42 (9.2%), Fabaceae 37 (8.1%), Brassicaceae 36 (7.9%), Lamiaceae 35 (7.7%), Poaceae 31 (6.8%). The first five genera according to the number of taxa were; Astragalus 9, Silene 8, Salvia 7, Trifolium 6 and Vicia 6. Within the scope of the study, a new and endemic onion species was discovered, named Adıyaman and this species was introduced to the literature as Allium adiyamanense Yıld. & Kılıç.
PubDate: Fri, 30 Dec 2022 00:00:00 +030
- Calculation of Dynamic Properties of Drug-Added Aqueous Solutions with T1
and T2 Relaxation Times
Authors: Sibel KORUNUR
Abstract: The development of modern spectroscopic methods has facilitated and accelerated structure analysis. The NMR method is the most popular way to perform structural analysis of compounds with very complex structures. D2O is a solvent that is frequently used in NMR analysis of both chemical molecules and many biological molecules such as drugs, proteins, and enzymes. In this paper, the study of residual water in proton drug-added protein solutions was carried out via NMR relaxation. The spin-lattice (T1) and the spin-spin relaxation (T2) times of residual water in drug-added protein solutions were studied depending on temperature by Avance Bruker 400 MHz 1H-NMR Spectrometer, and activation energies (E_a) and rotational correlation times (τ_0 and τ_c) have been determined for T1 and T2 relaxation times.
PubDate: Fri, 30 Dec 2022 00:00:00 +030
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