Improved synthetic wind speed generation using modified Mycielski approach

In this paper, novel approaches for wind speed data generation using Mycielski algorithm are developed and presented. To show the accuracy of developed approaches, we used three‐year collected wind speed data belonging to deliberately selected two different regions of Turkey (Izmir and Kayseri) to generate artificial wind speed data. The data belonging to the first two years are used for training, whereas the remaining one‐year data are used for testing and accuracy comparison purposes. The concept of distinct synthetic data production with correlation‐wise and distribution‐wise similar statistical properties constitutes the main idea of the proposed methods for a successful artificial wind speed generation. Generated data are compared with test data for both regions in the sense of basic statistics, Weibull distribution parameters, transition probabilities, spectral densities, and autocorrelation functions; and are also compared with the data generated by the classical first‐order Markov chains method. Results indicate that the accuracy and realistic behavior of the proposed method is superior to the classical method in the literature. Comparisons and results are discussed in detail. Copyright © 2011 John Wiley & Sons, Ltd.     

Hydrogen liberation from the dehydrocoupling of dimethylamine–borane at room temperature by using novel and highly monodispersed RuPtNi nanocatalysts decorated with graphene oxide

Addressed herein, we reported the fabrication of the graphene oxide (GO) supported monodispersed ruthenium–platinum–nickel (RuPtNi) nanomaterials (3.40 ± 0.32 nm) to be utilized as a catalyst in the process of dimethylamine borane (DMAB) dehydrogenation. The nanoparticles were fabricated through the ultrasonication method by co-reducing the Ru³⁺, Pt²⁺ and Ni²⁺ cations and then the nanomaterials were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), inductively coupled plasma optical emission spectrometry (ICP-OES), and X-ray photoelectron spectroscopy (XPS). The fabricated nanomaterials showed outstanding efficiency and remarkable reusability in addition to their record catalytic activity at low temperatures and with extreme low concentrations. They had a significantly high turnover frequency (TOF) (727 h^?1) and low activation energy (E_a) (49.43 ± 2 kJ mol^?1) for DMAB dehydrocoupling. To the best of our knowledge, RuPtNi@GO NPs become a very promising candidate as the best catalyst ever.     

A Comparative Study on Changes and Relationships of Kernel Biochemical Components in Different Types of Maize

A great deal of genetic variability and breeding efforts have yielded a number of specialty maize types. Little is known about how the off‐target traits in specialty maize kernel have changed and how they compare to those of standard maize genotypes. In this study, we compared the normal (NORMAL), high‐oil (HOM) and high‐protein maize (HPM) genotypes in terms of oil, protein, fatty acids and some mineral components. We also investigated the relationships among the evaluated traits in different kernel types. We detected a significant variation among the maize types for all of the investigated traits. Specialty maize genotypes had a superior performance for the traits they were specifically bred for, as well as kernel mineral content over the normal genotypes. HOM and HPM had similar values in terms of their fatty acid composition. However, they were different from the standard genotypes, with higher oleic and lower linolenic acid levels, which indicates that the specialty maize genotypes possess a better oil quality. Correlation analysis revealed that only three pairs of correlations out of 46 values had the same sign and a similar level of significance in different types. Such similarities or differences in correlation values for different types should be taken into account in the efforts for developing high quality maize genotypes.     

The effect of combined use of chitosan and PIPS on push-out bond strength of root canal filling materials

Adhesion of root canal filling materials to root dentin is important for the long-term success of the treatment. Push-out bond strength test is used to evaluate the adhesion capacity of root canal filling materials to root canal walls. The aim of the present study is to compare the bond strength of root canal filling materials to root dentin after irrigation with EDTA, chitosan and the combination of chitosan and PIPS irridation using push-out bond strength test. Forty-eight extracted teeth were resected until 13-mm long roots were obtained. Root canals were prepared with a size-25 OneShape instrument. Samples were divided into three groups each including 15 roots. Group 1: Canals were rinsed with 0.2% chitosan and subjected to laser irridation with PIPS at the same time. Group 2: Canals were rinsed with 0.2% chitosan. Group 3: Canals were rinsed with EDTA. All canals were filled with .06 tapered gutta-percha and AH-plus sealer. One-mm thick slices were taken from coronal, middle and apical one-thirds of the roots. Push-out bond strength was determined using a Universal Testing Machine. One root from each group was observed under SEM to evaluate the degree of smear removal. Statistical analysis was performed with Kruskall-Wallis test. Results showed that bond strength values were statistically similar in overall evaluation for all groups (p > .05). In segmental evaluation, group 1 revealed the highest bond strength in apical one-third compared to other groups (p < .05).     

Immobilization Horseradish Peroxidase onto UiO-66-NH2 for Biodegradation of Organic Dyes

Enzymes are extensively used as catalyst in several fields of production such as chemistry, and pharmaceuticals owing to their selectivity, efficiency and environmentally friendliness. However, their applications are often hindered due to their insufficient stability and difficulties in re-use. As a member of porous crystalline materials, metal organic frameworks are a promising enzyme carrier due to their multi-functional pore surfaces and robustness in variety of harsh conditions. In this study, the horseradish peroxidase (HRP) enzyme was immobilized onto UiO-66-NH₂ (Universitetet i Oslo) by a facile incubation method at the room temperature to improve the stability and reusability of enzyme. The prepared HRP@UiO-66-NH₂ bio-composite was characterized by using FT-IR, XRD and SEM. The crystal structure of MOF was well-preserved after enzyme immobilization. A colorimetric assay for enzyme activity after released from UiO-66-NH₂ has been employed based on the catalytic oxidation of phenol coupled with 4-aminoantipyrine. The robustness and activity of immobilized enzyme after released from UiO-66-NH₂ were investigated by biodegradation of methyl orange (MO) and methylene blue (MB) with several parameters such as pH, temperature, the dosage of H₂O₂ and the dye concentration with comparison to its free form. The optimum condition for dye degradation was obtained at basic conditions. The immobilized enzyme maintained its activity at elevated temperature while free enzyme lost its activity at the same conditions, attributed to the armoring effect of UiO-66-NH₂. According to the results of studied various parameters, MO and MB were biodegraded to 60% and 45%, respectively, within 60 min with the optimum conditions at pH 9 and 50 °C at a H₂O₂ dosage of 3%. The superior pH tolerance and stability suggest potential of UiO-66-NH₂ immobilized peroxidase enzyme in industrial applications.

     

The effect of sodium polymethacrylate on the rheology of the positive paste and performance of the lead-acid battery

Due to its rheological properties, positive lead-acid battery paste can be difficult to spread on lead current collectors accurately and efficiently under industry machinery and setting. Sodium polymethacrylate dispersant was studied as an effective positive paste additive that could lower the yield stress of the paste without affecting paste density and battery performance. Under a four-blade vane rheometer setup, stress growth and oscillatory amplitude strain sweep experiments evaluated the rheological properties of positive paste with the addition of varying amounts of sodium polymethacrylate. Further, the electrochemical effects of sodium polymethacrylate were also evaluated in 2V batteries by testing positive active material utilization and cycle life.     

Pt nanoparticles synthesized with new surfactants: improvement in C1–C3 alcohol oxidation catalytic activity

Platinum electrocatalysts were prepared using PtCl₄ as a starting material and 1-decylamine, N,N-dimethyldecylamine, 1-dodecylamine, N,N-dimethyldodecylamine, 1-hexadecylamine, and 1-octadecylamine as surfactants. These surfactants were used for the first time in this synthesis to determine whether the primary and/or tertiary structure and/or chain length of the surfactants, affects the size and/or activity of the catalysts in C₁–C₃ alcohol electro-oxidation reactions. Electrochemical measurements (cyclic voltammetry and chronoamperometry) indicated that the highest electrocatalytic performance was observed for the Pt nanocatalysts that were stabilized by N,N-dimethyldecylamine, and this has a tertiary amine structure with a short chain length (R = C₁₀H₂₁). The high performance may be due to the high electrochemical surface area, Pt(0)/Pt(IV) ratio, %Pt utility, and roughness factor (R _f). X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy, and transmission electron microscopy were used to determine the parameters that affect the catalytic activities.     

Thermal decomposition behavior of oligo(4‐hydroxyquinoline)

In this study, the kinetic parameters and reaction mechanism of decomposition process of oligo(4‐hydroxyquinoline) synthesized by oxidative polymerization were investigated by thermogravimetric analysis (TGA) at different heating rates. TGA‐derivative thermogravimetric analysis curves showed that the thermal decomposition occurred in two stages. The methods based on multiple heating rates such as Kissinger, Kim–Park, Tang, Flynn–Wall–Ozawa method (FWO), Friedman, and Kissinger–Akahira–Sunose (KAS) were used to calculate the kinetic parameters related to each decomposition stage of oligo(4‐hydroxyquinoline). The activation energies obtained by Kissinger, Kim–Park, Tang, KAS, FWO, and Friedman methods were found to be 153.80, 153.89, 153.06, 152.62, 151.25, and 157.14 kJ mol^?1 for the dehydration stage, 124.7, 124.71, 126.14, 123.75, 126.19, and 124.05 kJ mol^?1 for the thermal decomposition stage, respectively, in the conversion range studied. The decomposition mechanism and pre‐exponential factor of each decomposition stage were also determined using Coats–Redfern, van Krevelen, Horowitz–Metzger methods, and master plots. The analysis of the master plots and methods based on single heating rate showed that the mechanisms of dehydration and decomposition stage of oligo(4‐hydroxyquinoline) were best described by kinetic equations of A_n mechanism (nucleation and growth, n = 1) and D_n mechanism (dimensional diffusion, n = 6), respectively. POLYM. ENG. SCI., 54:992–1002, 2014. © 2013 Society of Plastics Engineers     

Gas chromatographic-olfactometric characterization of aroma active compounds in sun-dried and vacuum-dried tarhana

The influence of drying methods on the aroma active volatiles of sun-dried tarhana (SDT) and vacuum-dried tarhana (VDT) were compared using headspace SPME, GC-O and GC-MS. Although vacuum drying reduced the total amount of volatiles as compared to SDT (total FID peak area), more aroma active material was retained with VDT (total olfactory peak area). Vacuum drying retained a greater number of aroma active components (41) whereas the sun-dried method retained only 23. Aldehydes were the largest single class of aroma compounds in both types of tarhana: 17 in VDT and 10 in SDT. Other differentiating aroma compounds include alcohols, terpenes, and phenols such as geraniol, terpinolene, and 4-vinylguaiacol among others. A total of 22 aroma active components were present in greater amounts in the VDT versus only four aroma compounds present in greater amounts in the SDT.