Electrospun carbon nanofiber web electrode: Supercapacitor behavior in various electrolytes

Carbon nanofibers (CNFs) draw great interest due to their noticeable mechanical, electrochemical, and physical properties. In this study, polyacrylonitrile‐based CNFs are obtained via electrospinning technique. Thermal oxidation and low temperature (950 °C) carbonization are applied to the electrospun web in order to achieve CNF. Through the process, Fourier transform infrared‐attenuated total reflectance spectroscopy and Raman spectroscopic results are investigated. The electrochemical properties of the self‐standing CNF webs are examined with electrochemical impedance spectroscopy and cyclic voltammetry. In addition, various electrolyte solutions are studied to investigate the capacitive behavior of CNF webs. Electrolyte type variation has a significant effect on the capacitance results and high capacitance values are achieved in aqueous solution. According to the differing electrolyte types, specific capacitance values (C_sp) are recorded between 204 and 149 F g^?1 where maximum specific capacitance is obtained in 0.5 M H₂SO₄ as 204 F g^?1. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45723.     

Modification of the fuzzy analytic hierarchy process via different ranking methods

The use of fuzzy set theory in the analytic hierarchy process (AHP) has gained popularity in recent years as part of the multiple criteria decision-making (MCDM) process to more realistically reflect human judgment. However, due to the nature of fuzzy calculations, this situation imposes more computational load. The aim of this study is to propose methods for obtaining accurate weights from fuzzy pairwise comparison matrices with the least amount of computational load possible. In this context, two different fuzzy AHP (FAHP) methods based on fuzzy numbers ranking methods have been proposed and these proposed methods are compared with commonly accepted FAHP methods. Magnitude-based fuzzy AHP (MFAHP), which is one of the proposed methods, has outperformed all other methods according to accurate weight and computational load. Although the other proposed method, called the total difference-based fuzzy AHP (TDFAHP), gave better results than the frequently used Chang's fuzzy extent analysis method, it could not produce more accurate weight results than many other methods in general. But performance analysis shows that it is as good as the MFAHP in terms of computational load.     

Effect of potassium ion on the stability and release rate of hydrogen peroxide encapsulated in silica hydrogels

Hydrogen peroxide (H₂O₂) is encapsulated in silica hydrogels using sol‐gel method and the effects of the K⁺ : Na⁺ ion ratio on gelation time, hydrogel structure, stability, and release rate of H₂O₂ were investigated. As the amount of K⁺ ions increased relative to the amount of Na⁺ ions at the same pH, the gel structure became less compact and the pore diameter increased. Hydrogen peroxide retention values up to 90 and 80% were observed at the end of 7 and 20 days, respectively, in the presence of K⁺ ions at low pH values when the initial H₂O₂ concentration was 19.9 wt %. Release rate of hydrogen peroxide decreased with decreasing pH for the two K⁺ : Na⁺ ion ratios studied. This work presents an environmentally friendly, low cost, and easy to scale up method to increase the stability of high initial concentrations of H₂O₂ at room temperature and customize the release rate. © 2016 American Institute of Chemical Engineers AIChE J, 63: 409–417, 2017     

Measurement of mass attenuation coefficients,effective atomic numbers,and electron densities for different parts of medicinal aromatic plants in low-energy region

The mass attenuation coefficients(l/q) for different parts(root, flower, stem, and leaf) of three medicinal aromatic plants(Teucrium chamaedrys L. subsp. sinuatum,Rheum ribes, and Chrysophthalmum montanum) were measured using an ~(241)Am photon source in a stable geometry and calculated using the Monte Carlo N-Particle Transport Code System-extended(MCNPX) code and the WinXCOM program. The experimental and theoretical MCNPX and WinXCOM values exhibited good agreement.The measured mass attenuation coefficient values were then used to compute the effective atomic number(Z_(eff))and electron density(N_E) of the samples. The results reveal that S1-S(stem of Teucrium chamaedrys L. subsp. sinuatum) has the highest values of l/q and Zeff.     

Discriminating schizophrenia and schizo-obsessive disorder: a structural MRI study combining VBM and machine learning methods

Schizo-obsessive disorder is characterized by the clinical syndrome in which comorbid obsessive–compulsive disorder accompanies schizophrenia. A substantial number of studies have investigated the neuropsychological and clinical differences between schizophrenia and schizo-obsessive disorder. However, the neurostructural differences between these two groups have not been adequately investigated. The aim of this study was to explore gray matter differences between schizophrenia and schizo-obsessive patients using voxel-based morphometry and support vector machines combined with feature selection algorithm. Twenty-three schizophrenia and 23 schizo-obsessive patients matched by age, gender and handedness were recruited. Clinical assessments were completed in addition to high-resolution structural MRI scanning. Group differences were investigated using contrast maps, and significant regions were subjected to a feature selection and support vector machine hybrid model. In addition, voxel-of-interest values for the commonly shared brain areas between schizophrenia and OCD reported in previous meta-analyses were also used as inputs in this step. The results showed that schizo-obsessive patients had greater gray matter densities in paracentral areas (including supplementary motor area) and middle cingulate gyrus than schizophrenia patients. These brain areas together with the fronto-subcortical areas could successfully discriminate two groups with an accuracy of 78.26 %. Our results provide the first neuroanatomical evidence that schizo-obsessive disorder and schizophrenia may be two distinct clinical entities. Based on these findings, considering schizo-obsessive disorder as a subtype of schizophrenia is discernible.

     

Synthesis and Evaluation of Novel Functional Polymers Derived from Renewable Jasmine Lactone for Stimuli-Responsive Drug Delivery

Instances of synthetic polymers obtained from renewable feedstock with the possibility of post-synthesis functionalization are scarce. Herein, the first ever synthesis and drug delivery application of amphiphilic block copolymer (mPEG-b-PJL) derived from renewable jasmine lactone with free allyl groups on the backbone is presented. The polymer is synthesized via facile ring-opening polymerization and subsequently, UV mediated thiol-ene click chemistry is utilized for post-functionalization. The introduction of hydroxyl, carboxyl, and amine functionality to mPEG-b-PJL polymer is successfully established. As a proof-of-concept demonstration, doxorubicin (DOX) is conjugated on hydroxyl-terminated polymer (mPEG-b-PJL-OH) via redox responsive disulfide linkage to obtain PJL-DOX. PJL-DOX is readily self-assembled into micelles with an average hydrodynamic size of ≈ 150 nm and demonstrates reduction-responsive DOX release. Micelles are evaluated in vitro for cytocompatibility and selective drug release in cancer cells (MDA-MB-231) using 10 mm glutathione as a reducing agent. Cytotoxicity and microscopy results confirm a redox-triggered release of DOX, which is further confirmed by flow cytometry. The introduction of these novel functional polymers can pave the way forward in designing polymer-drug conjugate-based smart nano-carriers.     

Chemical composition and physicochemical properties of tubera salep produced from some Orchidaceae species

Salep samples obtained from 10 different Orchidaceae spp., namely Dactylorhiza osmanica var. osmanica, Ophrys mammosa, Orchis anatolica, Orchis coriophora, Orchis italica, Orchis morio, Orchis palustris, Orchis simia, Orchis tridentata and Serapias vomeracea ssp. orientalis, in Anatolia, were analyzed for moisture, glucomannan, starch, protein, ash contents, pH and viscosity values. Depending on the species, the samples showed statistically significant differences in glucomannan, starch and viscosity values. It was observed that the salep samples obtained from the tubers of O. italica, O. morio, O. anatolica and O. tridentata and S. vomeracea ssp. orientalis, respectively, had higher glucomannan contents and viscosities. To ensure a supply of high-quality salep, the uncontrolled collection of tubers from the wild, especially the species O. italica, O. morio and O. anatolica, should be prevented, and research into methods of cultivation should be carried out.     

A review of thermoplastic composites for bipolar plate applications

Bipolar plates are responsible for functions of vital importance to the long‐term performance of fuel cells. They play crucial roles in water and gas management, mechanical strength and electrical conductivity. It also significantly contributes to the volume, weight and cost of fuel cell stacks. The properties of bipolar plates are affected by the materials and processes used in the manufacturing of the plates. The objective of this article is to review the use of thermoplastic materials as polymer matrices in bipolar plate applications. Conductive composites consisting of different types and blends of thermoplastic polymers are detailed discussed. The effects of filler types and processing conditions are given. Several thermoplastic blends consisting of carbon black, carbon nanotube and graphite are evaluated. The dispersion of conductive fillers, in particular, polymer composites and polymer blend composites is also given. Copyright © 2013 John Wiley & Sons, Ltd.     

Characterization of cordierite based h-BN doped ceramics as an electronic substrate/circuit board material

In this study, h-BN was added to the cordierite composition obtained from zeolite, which was prepared by the determined stoichiometry to facilitate machinability and increase thermal conductivity. Sintering behavior, hardness, machinability, and thermal/electrical properties of the samples obtained by sintering the compounds at different times were investigated. Thanks to these features, it is aimed to use cordierite as an alternative material to integrated circuit substrates and electronic packaging materials. The produced samples were analyzed by X-ray diffraction analysis, examined by scanning electron microscopy, and field emission scanning electron microscopy. Afterward, thermal properties such as thermal diffusivity, thermal conductivity, and electrical properties such as electrical conductivity and dielectric permittivity were measured. The hardness and machinability of samples were investigated. Cordierite, spinel, glassy phase, and h-BN phase were detected, and it was observed that the blocky cordierite grains turned into equiaxed grains with the increase of the h-BN. According to the results obtained from the thermal conductivity test, it was seen that the h-BN additive increased the thermal conductivity value in general. In addition, it was determined that with the increase of h-BN, the hardness decreased, and the machinability properties of the samples improved.     

Characterization of Turkish Olive Oils by Triacylglycerol Structures and Sterol Profiles

A characterization study of Turkish monovarietal olive oils using chemical variables such as fatty acid, sn‐2 fatty acid, triacylglycerol, and sterol composition is presented. A total of 101 samples of Olea europaea L. fruits from 18 cultivars were collected for two crop years from west, south, and southeast regions of Turkey. Olives were processed to oil and olive oil samples were evaluated for their triacylglycerol structures and sterol composition. Oleic acid content ranged from 60.15 to 80.46 % of total fatty acids and represented 70.90–89.02 % of sn‐2 position triacylglycerols. Major triglycerides of oil samples were triolein, palmitodiolein, dioleolinolein, palmitooleolinolein, dipalmitoolein, and stearodiolein. Triolein values were between 24.72 and 48.64 % and compatible with the fatty acid composition. Total sterol content varied from 1,145.32 to 2,211.77 mg/kg and Edremit yagl?k stood out because of its high sterol content. A one‐way analysis of variance revealed significant differences for variables among cultivars. Principle component analysis enabled the classification of common varieties on the basis of analytical data. Sterol composition achieved more relevant discrimination than fatty acid and triglyceride composition. Classification according to geographical origin was performed by discriminant analysis.