Thermal Oxidation Kinetics of Refined Hazelnut Oil

In this study, oxidation kinetics of refined hazelnut oil heated at the temperature range from 80 to 180 °C was evaluated. The changes in peroxide value, p‐anisidine value, polymer triglyceride content, α‐tocopherol content, and color values during oxidation were best fitted to zero‐order kinetic model. The rate constants for the p‐anisidine value, polymer triglyceride content, and degradation of α‐tocopherol of hazelnut oil increased at the temperatures between 80 and 160 °C, while the rate constant for peroxide value decreased at the temperatures between 80 and 140 °C. The activation energies for the formation of peroxides (at 80–140 °C), secondary oxidation products such as alkenals, the polymer triglycerides, and degradation of α‐tocopherol were found as 47.49, 29.95, 52.65, and 14.22 kJ mol^?1, respectively. The induction period of hazelnut oil was observed to reduce with increasing oxidation times. The increase in the b* value with the oxidation time and temperature was attributed to the fact that the heating process intensified the yellow color of the oil.     

Patterned polymer carpets

For the development of polymer carpets as active devices for micro- and nanotechnology, a control of the polymer carpet morphology and especially control of the stimulus responsive polymer brush is needed. Here, we report on the first example for the fabrication of patterned polymer carpets. On a two-dimensional framework of fully crosslinked and chemically patterned nanosheets, polymer brushes of styrene and 4-vinyl pyridine were grafted by self-initiated surface photopolymerization and photografting (SIPGP). It was found that polymer grafting by SIPGP occurred over the entire nanosheets but with a preferred grafting on the amino functionalized nanosheet areas. This results in continuous polymer carpets with an intact nanosheet framework but with amplification of the chemical patterning into a three dimensional topography of the grafted polymer brush. In the case of negative patterned nanosheets, the patterned carpet could be prepared as freestanding ultrathin membranes. Furthermore, swelling experiments with poly(4-vinyl pyridine) carpets showed that the patterns induces a directional buckling of the flexible polymer carpet. This may open the possibility of the development of micro- or nanoactuator devices with anisotropic responds upon environmental changes.     

HRP immobilized microporous Poly(styrene-divinylbenzene-polyglutaraldehyde) monolith for forced flow injected phenol biosensing

A colorimetric detection system based on horseradish peroxidase (HRP) immobilized microporous Poly(styrene-divinylbenzene-polyglutaraldehyde) monolith was developed for phenol biosensing. The incorporation of the aldehyde groups to the backbone of the microporous (90%) monolith was achieved by the polymerization of the continuous phase of a high internal phase emulsion. HRP was chemically immobilized onto the inner walls of the micropores of the monolith via the aldehyde groups. HRP immobilized microporous monolith (HRP-MM) was used as a biocatalytic cell under forced flow conditions in a flow injection system. A carrier stream containing 4-aminoantipyrine (4-AAP) as color reagent was flowed through the HRP-MM at various flow rates ranged between 0.1-15 mL min^-1. The analytical parameters of response time, detection limit and linear range varied at the range of 1-60 s, 1-250 μM, and 0.25-2 mM, respectively. The results showed that the most accurate phenol biosensing was obtained at the flow rate of 1 mL min^-1. The microarchitected structure of the monolith improved the mass transferring conditions for the enzymatic reaction due to the forced flow through the micropores. The detection system presented a satisfactory precision evaluated by relative standard deviation of 1.1% (n = 13) and recovery of 100% at the flow rate of 1 mL min^-1. The system showed 60% of its initial signal from 12th day up to the two months.     

A new dual entropy core true random number generator

The entropy produced by a conventional single chaotic map based true random number generator (TRNG) is usually limited due to the finite number of Lyapunov exponents. In this work, we present a new dual entropy core TRNG architecture which is capable of producing high levels of randomness using hardware redundancy. Mathematical models of conventional and proposed TRNG architectures have been developed for a comparative analysis of the statistical and randomness properties. Our theoretical studies showed that the proposed architecture which employs Bernoulli map as the entropy source, has an inherently symmetric probability density function with zero mean. Using a practical information metric, T-entropy, we demonstrated that the proposed architecture performs better in terms of randomness, for a wide range of control parameter values when compared to its single entropy core counterpart. A proof of concept prototype of the proposed architecture is designed and implemented using a field programmable analog array integrated circuit. Random numbers acquired from the prototype have successfully passed all NIST 800.22 statistical tests.     

Effect of fruit canopy positions on the properties of apricot (Prunus armeniaca L.) varieties

Effect of fruit position in the tree on properties of two commercially important apricot varieties (Hac?halilo?lu and Kabaa??) was investigated. Principal component analysis separated apricots based on their variety and canopy position. Hac?halilo?lu variety was distinguished from Kabaa?? variety by its higher pH, weight, dry matter (DM), soluble solid, citric acid, and catechin content. Major features which contribute to variation of the canopy position were β‐carotene, malic acid, catechin, ascorbic acid, soluble solid content, DM, malic acid, and neochlorogenic acid. Fruits located on the top of the tree were richer in phenolic compounds and exhibited higher degree of antioxidant activity measured by 2.2′‐azinobis[3‐ethylbenzthiazoline‐6‐sulphonic acid] (ABTS) method than those located on the bottom of the tree. Except for chlorogenic and neochlorogenic acids, all other forms of phenolic compounds were higher in concentration in the fruits located on the top of the canopy especially for the Hac?halilo?lu variety.

Practical applications

The results of this study may be of interest for apricot breeders as it provides important information about cultivar specific canopy effect on fruit quality. Furthermore, the results can be used by apricot producers for canopy management and pruning strategies to create of homogenous microclimate in the fruit canopy which would limit quality variation.     

3D numerical analysis of drilling process: heat,wear, and built-up edge

In this study, a 3D finite element model is developed to investigate the drilling process of AISI 1045 steel, and particularly, the heat and wear on the drill faces. To model drill wear, a modified Usui flank wear rate is used. Experiments are used for the verification of the simulated model and the evaluation of the surface roughness and built-up edge. A comparison of the predicted and experimental thrust forces and flank wear rates revealed that the predicted values had low errors and were in good agreement with the experimental values, which showed the utility of the developed model for further analysis. Accordingly, a heat analysis indicated that approximately half the generated heat in the cutting zone was conducted to the drill bit. Furthermore, material adhesion occurred in localized heat areas to a great extent, thus resulting in wear acceleration. A maximum flank wear rate of 0.026 1 mm/s was observed when the rotary speed and feed rate were at the lowest and highest levels, respectively. In the reverse cutting condition, a minimum flank wear rate of 0.016 8 mm/s was observed.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-018-0223-z     

A new radiation shielding material: Amethyst ore

This paper describes a new radiation shielding material, amethyst ore. We have determined the elemental composition of amethyst using WDXRF spectroscopy technique. To see the shielding capability of amethyst for several photon energies, these results have been used in simulation process by FLUKA Monte Carlo radiation transport code. Linear attenuation coefficients have been calculated according to the simulation results. Then, these values have been compared to a fine shielding concrete material. The results show that amethyst shields more gamma beams than concrete. This investigation is the first study about the radiation shielding properties of amethyst ore.     

Effect of physico‐chemical properties of tropical starches and hydrocolloids on rice gels texture and noodles water retention ability

The links between the physico‐chemical properties of rice flour (RF), cassava (CS), sago (SS), canna (CaS), sweet potato (SPS), and mung bean (MS) starches, and the gelling properties of rice flour blends with these starches in different proportions (0, 20, 40, 60, 80, and 100% pure starches) and with xanthan (XG) and carrageenan (CG) gums were studied. Water retention ability of starches and hydrocolloids blends in noodle systems during drying at 40°C was also investigated. The mean granule diameter and AM content values of RF, CS, SPS, SS, CaS, and MS were in the range of 12.8–41.0 µm and 21.9–39.4%, respectively. Thermal properties showed significant differences (p < 0.05) between the starches in terms of gelatinization temperature and enthalpy, as well as retrogradation tendency. Different starches produced gels with a wide range of textural properties. Results confirmed the role of AM content in determining the gel strength, and indicated a possible role of retrogradation in increasing the dissipation of mechanical energy during compression and relaxation tests, which can have an effect on mouth feel. Blends of RF with other starches and hydrocolloids generally improved the characteristics of RF‐based gels, by increasing gel strength. In particular, the use of MS markedly increased the strength of RF‐based gels. Addition of hydrocolloids significantly reduced the drying rate of noodles, although overall water retention ability was reduced only to a limited extent. This may be used to produce starch‐based products, especially noodles, in a range of desired characteristics.     

Over 100 mV VOC Improvement for Rear Passivated ACIGS Ultra-Thin Solar Cells

A decentralized energy system requires photovoltaic solutions to meet new aesthetic paradigms, such as lightness, flexibility, and new form factors. Notwithstanding, the materials shortage in the Green Transition is a concern gaining momentum due to their foreseen continuous demand. A fruitful strategy to shrink the absorber thickness, meeting aesthetic and shortage materials consumption targets, arises from interface passivation. However, a deep understanding of passivated systems is required to close the efficiency gap between ultra-thin and thin film devices, and to mono-Si. Herein, a (Ag,Cu)(In,Ga)Se₂ ultra-thin solar cell, with 92% passivated rear interface area, is compared with a conventional nonpassivated counterpart. A thin MoSe₂ layer, for a quasi-ohmic contact, is present in the two architectures at the contacts, despite the passivated device narrow line scheme. The devices present striking differences in charge carrier dynamics. Electrical and optoelectronic analysis combined with SCAPS modelling suggest a lower recombination rate for the passivated device, through a reduction on the rear surface recombination velocity and overall defects, comparing with the reference solar cell. The new architecture allows for a 2% efficiency improvement on a 640 nm ultra-thin device, from 11% to 13%, stemming from an open circuit voltage increase of 108 mV.