Chemical changes of three native Turkish hazelnut varieties (Corylus avellana L.) during fruit development

Three native hazelnut varieties from Turkey, namely, Tombul, Palaz, and Badem, were examined for their proximate composition, minerals, and fatty acid profiles, as well as polyphenol oxidase (PPO), peroxidase (POD), and lipase activities during fruit development stages (early stage: ES, middle stage: MS, and harvest stage: HS). Proximate composition varied considerably (dry weight basis) from ES to MS. Fat was the predominant component at all stages and showed increasing trends. Six essential minerals (calcium, iron, magnesium, phosphorus, potassium, and zinc) were analysed (dry weight basis). Consuming recommended daily amount of 42.5 g hazelnut at HS supplies 23.3–25.0% of phosphorus, 11.6–18.1% of magnesium, 7.0–18.9% of iron, 4.9–8.9% of zinc, 5.1–5.7% of calcium, and 5.1–5.3% of potassium for recommended dietary allowances or adequate intake for adults. Significant (P < 0.05) decreasing trends were found in all mineral contents from early development to maturity, with some exceptions. Sixteen fatty acids were identified, among which 18:1ω9 was by far the most predominant one, followed by 18:2ω6, 16:0, and 18:0. As expected, total monounsaturated fatty acids constituted the main group of fatty acids ranging from 75.51 to 81.07% in Tombul, from 78.21 to 82.71% in Palaz, and from 73.69 to 81.65% in Badem through the maturation stages. In contrast, total polyunsaturated fatty acids showed decreasing trends from ES to HS. No significant changes (P > 0.05) were observed in total saturated fatty acids at different maturation stages. Tombul variety had the lowest PPO activity compared to those of Palaz and Badem. Badem showed highest POD activity compared to Tombul and Palaz at three stages of maturation and significant decreases (P < 0.05) in all hazelnut samples were observed in POD activity from ES to HS. No lipase activity was detected in any hazelnut samples at ES and MS, except in Badem at MS. In contrast, lipase activity was detected in all hazelnut samples at HS. These results suggest that some proximate compositions, minerals, and fatty acids gave good indications during fruit development stages, whereas enzymatic activities of PPO, POD, and lipase behaved differently among varieties and fruit development stages.     

Electrocatalytic Reduction of Oxygen on a Pd Ad-Layer Modified Au(111) Electrode in Alkaline Solution

Oxygen reduction was studied on palladium, cadmium and zinc ad-atom modified single crystal Au(111) electrodes. The electrodes were modified by underpotential deposition process and their activity towards oxygen reduction was studied in alkaline media by voltammetry. The reduction peaks obtained were compared with those of bare Au(111), Pd disc and bulk deposited Cd electrodes. Enhanced catalytic activity of the Au(111) electrode in the presence of Pd, Cd and Zn ad-layer can be attributed to a change in surface charge and energy by ad-layer formation. In oxygen saturated medium a well defined sharp reduction peak was observed at ?0.12 V for 1/5 ML Pd ad atom modified Au(111) electrode while it was positioned at ?0.18 V on a Pd disk electrode. The best shift in reduction peak potential was obtained with 2/5 ML Pd ad atom modified Au(111) electrode with similar current density of Pd disc electrode.     

‘Fairy Chimney’‐Shaped Tandem Metamaterials as Double Resonance SERS Substrates

A highly tunable design for obtaining double resonance substrates to be used in surface‐enhanced Raman spectroscopy is proposed. Tandem truncated nanocones composed of Au‐SiO₂‐Au layers are designed, simulated and fabricated to obtain resonances at laser excitation and Stokes frequencies. Surface‐enhanced Raman scattering experiments are conducted to compare the enhancements obtained from double resonance substrates to those obtained from single resonance gold truncated nanocones. The best enhancement factor obtained using the new design is 3.86 × 10⁷. The resultant tandem structures are named after “Fairy Chimneys” rock formation in Cappadocia, Turkey.     

Assessment of DFG-S19 method for the determination of common endocrine disruptor pesticides in wine samples with an estimation of the uncertainty of the analytical results

A gas chromatographic method for the determination of endocrine disruptor pesticides (Chlorpyrifos, Penconazole, Procymidone, Iprodione, Bromopropylate and Lambda-Cyhalothrin) in wine samples is described. A general DFG-S19 method for residual pesticide determination in all kind of food stuff was investigated to simplify and adopt for wine samples in this work. Alternative sample preparation routes were elucidated and compared according to their recovery values. Four different separation techniques were tested and the method employing florosil column after a LLE procedure was applied for wine samples with satisfactory recovery ratios (72–97%). The pesticides were extracted from the sample by cyclohexane–ethyl acetate mixture (1:1 v/v) and cleaned up by florosil column. The regression coefficients were at least 0.99 and relative standard deviations were no higher than 16%. Detection limits were in the range of 0.6–2.9 ng/mL and the relative expanded measurement uncertainties were calculated in the 7–22% range.     

Some properties of thin medium density fiberboard panels treated with sunflower waste oil vapor

The objective of this study was to investigate the effect of hot waste oil vapor on some of the physical and bending properties of commercially manufactured thin medium density fiberboard (tMDF) panels. The samples were treated with waste oil vapor at a temperature of 220 °C for 10 and 20 min time durations. Based on the findings in this work, the water absorption and thickness swelling of the samples were improved by the treated panels with hot vapor oil and heat. It appears that the samples had some discoloration as a result of treatment processes. It was also observed that modulus of rupture (MOR) and modulus of elasticity (MOE) of the samples were adversely influenced. However, it seems that the thermal conductivity of the samples enhanced by such treatments. Panel products treated with these processes could have some promising potential in various applications including outdoor use.     

A rapid HPLC method for determination of Sudan dyes and Para Red in red chilli pepper

A rapid high-performance liquid chromatography (HPLC) system consisting of an ultraviolet-visible (UV–VIS) detector was developed for the separation and determination of Sudan dyes (I, II, III, and IV) and Para Red in red chilli peppers. The chromatographic separation was achieved on a reverse phase C₁₈ column with isocratic elution, using a mobile phase of acetonitrile/methanol (80:20, v/v); detector was set at 506 nm. All four Sudan dyes and Para Red were separated in less than 9 min. Among 80 red chilli peppers screened, only one of them contained 0.10, 0.04, and 0.05 mg/kg Sudans I, III, and IV, respectively. No Sudan II and Para Red were detected in any of the red chilli peppers analysed. The method was ‘in-house’ validated using red chilli peppers based on following criteria: limit of detection (LOD), limit of quantification (LOQ), recovery, repeatability, reproducibility, and linearity in red chilli peppers. Depending on the dye involved, LOD and LOQ were in the range of 1.2–5.4 and 4–18 μg/kg in red chilli, respectively. The recovery, repeatability (expressed as coefficient of variation, CV_r), and reproducibility (CV_R) varied from 89 to 98%, from 0.82 to 4.09%, and from 1.33 to 4.65%, respectively. Linearity obtained for all dyes and Para Red were all r² > 0.9999 (in the range of 0.01–5 mg/l). The applicability of the method to the determination of Sudan dyes and Para Red in red chilli peppers was demonstrated. This method has potential to be used for illegal Sudan dyes and Para Red in red chilli peppers and some foodstuffs due to its simple, reliable, rapid, and excellent precision.     

Interference effect of iron on the determination of gold in geological samples using the vapor generation technique and preconcentration in a graphite furnace

A vapor generation procedure for the production of volatile species of Au was studied using electrothermal atomic absorption spectrometry (ETAAS). The interference effects of iron in solution and in the gas phase in a quartz T-tube were studied for the first time in detail. A dual vapor generation system was used for a single heated quartz tube atomizer, so that it was possible to study interferences and classify them regarding their origins. Results show that both gas-phase and liquid-phase interferences are present. It was also concluded that since the total interference effect causes the Au signal to be lower as compared to only the presence of gas-phase interactions in the experiment, the net liquid-phase interference from Fe should be suppressed. The method described in this study was used for the determination of gold in an ore reference material, Carlin Ore Mine, for the purpose of demonstrating the ability of the reported method to determine Au without any extraction procedure.     

A comparison of regression methods for remote tracking of Parkinson’s disease progression

Remote patient tracking has recently gained increased attention, due to its lower cost and non-invasive nature. In this paper, the performance of Support Vector Machines (SVM), Least Square Support Vector Machines (LS-SVM), Multilayer Perceptron Neural Network (MLPNN), and General Regression Neural Network (GRNN) regression methods is studied in application to remote tracking of Parkinson’s disease progression. Results indicate that the LS-SVM provides the best performance among the other three, and its performance is superior to that of the latest proposed regression method published in the literature.     

Frequency-Dependent Dynamic Phase Diagrams in Ising System with Fe<Subscript>4</Subscript>N Structure

We present a study, within a mean-field approach, of the kinetics of the mixed spin-1 and spin-3/2 Ising model with Fe₄N structure in the presence of a time-dependent oscillating external magnetic field. We employ the Glauber transition rates to construct the mean-field dynamical equations. We investigate the time dependence of average magnetizations and the thermal behavior of the dynamic order parameters. From these studies, we obtain the dynamic phase transition (DPT) points and construct the dynamic phase diagrams (DPD) in different frequencies. Phase diagrams contain three mixed and four fundamental phases besides that many special points and reentrant behavior that strongly depend on interaction parameters.