Effect of Thermal and High Electric Fields on Secondary Structure of Peanut Protein

This study evaluated the effect of the thermal and high electric field stresses on the secondary structure conformation of peanut protein using Fourier transform infrared spectroscopy. The amide I region between the wavelengths 1700–1600 cm^–1 of the spectra were studied for different thermal and high electric field treatments. Within thermal treatments, both hot air roasting and microwave processing treatments were evaluated. Hot air treatments were performed at temperatures of 50, 75, and 100°C from 15, 30, and 45 min while the microwave treatments were conducted at the same temperatures, but for 5, 10, 15, and 20 min. Three experimental conditions were evaluated for the electric field intensity of 10, 15, and 20 kV for 60, 120, and 180 min. Changes were observed at 1654–1650 cm^–1, indicating conformational changes in the α-helix secondary structure. Similar changes were observed at various other wavelengths indicating changes in the 3/10 helix, β-sheets and random coils present in the protein. With an increase in the treatment time, the secondary structure reorganizations increased with the creation of new random coils and aggregated strands. Curve-fitting using Gaussian band shapes further supported the observations. In vitro protein digestibility studies were also performed and the protein changes also supported the observations from the spectra.     

Nonlinear seismic response evaluation of tunnel form building structures

The occurrences of (M_w=7.4) Kocaeli and (M_w=7.1) Duzce earthquakes in Turkey in 1999 once again demonstrate the nondamaged and high performance conditions of RC shear wall dominant structures commonly built by using the tunnel form technique. This study presents their seismic performance evaluation based on the nonlinear pushover analyses of two case studies. The contribution of transverse walls and slab-wall interaction during the 3D action, the effects of 3D and 2D modeling on the capacity-demand relation, as well as diaphragm flexibility, torsion and damping effects were investigated. An effort was spent to develop a shell element having closing-opening and rotating crack capabilities. This study shows that the applied methodology has a considerable significance for predicting the actual capacity, failure mechanism, and evaluation of the seismic response of tunnel form buildings.     

Preparation,electrochemistry and optical properties of unsymmetrical phthalocyanines bearing morpholine and tert-butylphenoxy substituents

The synthesis of novel, unsymmetrical, octasubstituted metal-free and metallophthalocyanines (zinc, cobalt) bearing one chlorine, one morpholine moieties and six 4-tert-butylphenoxy substituents was achieved by a statistical condensation reaction of two corresponding phthalonitriles. The new compounds have been characterized by using elemental analyses, UV–vis, IR, ¹H NMR and mass spectroscopic data. Voltammetric and spectroelectrochemical studies are in harmony with the reported metallophthalocyanine complexes, which support the proposed structure of the complexes.     

Electrocatalytic oxygen reduction and hydrogen evolution reactions on phthalocyanine modified electrodes: Electrochemical, in situ spectroelectrochemical, and in situ electrocolorimetric monitoring

This study describes electrochemical, in situ spectroelectrochemical, and in situ electrocolorimetric monitoring of the electrocatalytic reduction of molecular oxygen and hydronium ion on the phthalocyanine-modified electrodes. For this purpose, electrochemical and in situ spectroelectrochemical characterizations of the metallophthalocyanines (MPc) bearing tetrakis-[4-((4′-trifluoromethyl)phenoxy)phenoxy] groups were performed. While CoPc gives both metal-based and ring-based redox processes, H₂Pc, ZnPc and CuPc show only ring-based electron transfer processes. In situ electrocolorimetric method was applied to investigate the color of the electrogenerated anionic and cationic forms of the complexes. The presence of O₂ in the electrolyte system influences both oxygen reduction reaction and the electrochemical and spectral behaviors of the complexes, which indicate electrocatalytic activity of the complexes for the oxygen reduction reaction. Perchloric acid titrations monitored by voltammetry represent possible electrocatalytic activities of the complexes for hydrogen evolution reaction. CoPc and CuPc coated on a glassy carbon electrode decrease the overpotential of the working electrode for H⁺ reduction. The nature of the metal center changes the electrocatalytic activities for hydrogen evolution reaction in aqueous solution. Although CuPc has an inactive metal center, its electrocatalytic activity is recorded more than CoPc for H⁺ reduction in aqueous solution.     

A "grow-in-place" architecture and methodology for electrochemical synthesis of conducting polymer nanoribbon device arrays

Fully enclosed horizontal nanochannels, in a prearranged array on a substrate and with built-in electrical contacts and chemical access regions, were used as growth templates for electrochemical synthesis of conducting polymer nanoribbons. In this "grow-in-place" approach, the nanochannel templates are part of the final array structure and remain after fabrication of the nanoribbons. The built-in electrical contacts, which provide the electrical potential for electrochemical polymerization, also remain and become contacts/interconnects to the array components. The grow-in-place architecture and methodology remove the need for template dissolution, any post-synthesis nanoribbon "grow-and-then-place" manipulation, and any post-synthesis electrical contacting. The fact that the templates are fully enclosed prohibits dendrite formation during growth, ensures precise dimensionality, and gives the encapsulation needed in any real device application. In this report the grow-in-place approach to electrochemical polymerization is used to produce polyaniline nanoribbons. These were found to be fibrils and not tubes and to grow from the central region of the growth-template cross-section and not from the template walls. Two-point and four-point electrical characterization of these polyaniline nanoribbons, obtained using the built-in electrodes, was employed to yield the true polyaniline conductivity and to assess the ohmicity of the contacting approach. Conductivity studies, done as a function of nanoribbon width, show conductivity increases as the width decreases. We also show that our grow-in-place approach may be used for chemical polymerization. However, at least for polyaniline, electrochemical polymerization is superior since it does not suffer from diffusion-limited growth and allows precise placement of the nanoribbons in the growth channel.     

High purity synthesis of ZrB2 by a combined ball milling and carbothermal method: Structural and magnetic properties

The present work provides a new insight into the high purity synthesis of zirconium diboride (ZrB₂) powders and a method of controlling impurity during the synthesis process. The single phase ZrB₂ nano-powder was synthesized by a combined ball milling and carbothermal method using zirconium oxide (ZrO₂), boron oxide (B₂O₃) and carbon (C) as starting materials. The reaction pathway, phase purity, and morphology of the ZrB₂ produced are elucidated from X-ray diffraction (XRD) and scanning electron microscopy studies. The details of the impure phases generated during synthesis were obtained from multi-phase Rietveld refinements of XRD data. Experiments revealed that the method of synthesis carried out at 1750?°C involving ZrB₂:B₂O₃:C at a molar ratio of 1:4.5:7.5 could produce highly pure ZrB₂ nano-powders of 67?nm average crystallite size. The magnetometry studies on such pure form of ZrB₂ nano-powders indicated that both paramagnetic and diamagnetic characteristics coexisted in ZrB₂, which could be attributed to its polycrystallinity.     

Preparation of hydrophilic woven fabrics: Surface modification of poly(ethylene terephthalate) by grafting of poly(vinyl alcohol) and poly(vinyl alcohol)-g-(N-vinyl-2-pyrrolidone)

One of the most industrially important synthetic textile materials, woven poly(ethylene terephthalate) (PET) fabrics, have limitations in the usage of casual apparel applications due to their unwanted hydrophobicity. For that reason, in this study, to impart permanent hydrophilicity to the PET fabrics, hydrophilic poly(vinyl alcohol) (PVA) and a PVA-based copolymer were introduced to the alkaline hydrolysis pretreated PET surface by graft copolymerization for the first time. The graft modification of PET fabric surface was performed with an industrial-adaptable approach. The synthesis of a novel PVA-g-(N-vinyl-2-pyrrolidone) copolymer was achieved by the introduction of glycidyl methacrylate monomer to the PVA backbone. The structure of the copolymer was evidenced by attenuated total reflection–Fourier transform infrared spectroscopy and ¹H-NMR techniques. The introduction of PVA and copolymer structures with desired functional groups to the PET fabric surface was confirmed with the X-ray photoelectron spectroscopy technique. It was obtained that the contact angle–wetting time of PET fabric (145° and 98 s) could be dropped to 37° and 0.1 s and 64° and 0.7 s after PVA and copolymer grafting, respectively. This suggests that the graft-modified PET fabrics may find the potential of use in the textile applications as the alternative hydrophilic materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48584.     

A Review of the Authentication of Wine Origin by Molecular Markers

Viniculture is one of the oldest agricultural activities of humans. The selection of grape varieties is of primary concern for factors such as wine quality and is dependent on the grapevine variety employed. Under today's conditions, and the sanctions imposed by world markets in the competitive wine sector, wine producers have been compelled to use different analysis methods in order to prove quality. However, some of these methodologies can be very time‐consuming. Recently, highly polymorphic molecular markers have been applied to the characterisation and differentiation of grapes in must and wine. With DNA profiles, the determination of origin and the use of this information on the label can act as a powerful quality control tool in the wine sector. In this review, the advantages of molecular markers and the applications of the markers in determining the origin in must and wine, are discussed with the aim of bringing together the limited number of studies (studies conducted with DNA markers) related to the determination of the grape variety in must and wine.     

Numerical study on photovoltaic/thermal systems with extended surfaces

The current study presents a novel and straightforward approach for simulating photovoltaic/thermal (PV/T) systems using the commercial computational fluid dynamics (CFD) solver ANSYS‐FLUENT. Instead of resolving the natural convection within the air gap between the PV and the glass cover, the effective thermal conductivity approach is implemented. Moreover, the solar radiation incident on the PV layer is directly included in the energy equation of the PV domain to evaluate the resultant power output and heat generation. The validity of these implications is proven by comparing predicted data with experimental data from the literature. Comparative results reveal a root‐mean‐square error of 7% and 2% for the PV temperature and the outlet air temperature, respectively. A comprehensive numerical analysis is also conducted for a PV/T system with and without finned surfaces. In the parametric study, the impacts of varying a number of design parameters, operating conditions, and weather data over a wide range are assessed. Results reveal that channel height and air velocity have the greatest impact on the overall efficiency and outlet air temperature of a PV/T system. An optimization study is also conducted using the response surface methodology to obtain optimal values of design parameters and operating conditions for this system. The highest overall efficiencies and outlet air temperatures are achieved in PV/T systems comprising narrow channel geometries, regardless of the operating conditions or weather data considered. Optimal conditions are achieved for a collector with a collector length of 1.5 m, a channel height of 1 cm, and an air velocity of 2.3 m/s. For the optimal design, overall efficiency and outlet temperature values are evaluated as 53.4% and 310.9 K, respectively. Sensitivity analyses also observe the impact of adding fins to the air channel, and it is concluded that the addition of fins improves the overall efficiency of the PV/T system by up to 19%. However, adding fins does not significantly affect the outlet air temperature; nor does it improve the overall efficiency of the PV/T system beyond a critical channel height.