Cathodic electrodeposition of Y(OH)3 and Y2O3 nanostructures from chloride bath. Part II: Effect of the bath temperature on the crystal structure,composition and morphology

Ultra-fine nanoparticles, mono-dispersed nanospheres and nanorods of Y(OH)₃ and Y₂O₃ were successfully prepared via electrodeposition from chloride bath at different temperatures of 10, 25, 40 and 80 °C followed by heat-treatments at 600 °C in dry air atmosphere. Thermal behavior of the hydroxide samples was investigated by differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The structural and morphological characteristics of the products were determined by X-ray diffraction (XRD), FT-IR, scanning and transmission electron microscopy (SEM and TEM). Effects of bath temperature on the mechanism of base electrogeneration and deposit formation on the cathode surface were proposed and discussed. The results showed that the crystal structure, composition and morphology of the products are mainly affected by the temperature of electrodeposition bath.     

Further Increase of T c in Y-Ba-Cu-O Superconductors

This paper presents the synthesis and characterization of three new Y-based high temperature-superconducting compounds having relatively higher transition temperature T _c compared with that of the Y-123, Y-124, and Y-247. The electrical resistivity measurements indicate the onset critical temperatures as high as 98 K. Atomic compositions of these new Y-Ba-Cu-O superconductors are Y₂Ba₃Cu_5.2O _x , Y₂Ba₅Cu₉O _x , and YBa₄Cu₅O _x . The X-ray analysis has shown that they have a similar crystalline structure as Y-123 phases.     

Effects of rotation and feedback control on Bénard–Marangoni convection

The effect of a feedback control on the onset of steady and oscillatory Bénard–Marangoni instability in a rotating horizontal fluid layer is considered theoretically using linear stability theory. It is demonstrated that generally the critical Marangoni number for transition from the no-motion (conduction) to the motion state can be drastically increased by the combined effects of feedback control and rotation. The role of the controller gain parameter on the Pr-Ta and Pr-R/R_c parameter spaces, dividing stability domains into which either steady or oscillatory convection is preferred, is determined.     

Viscosity estimation of triacylglycerols and of some vegetable oils, based on their triacylglycerol composition

The experimentally determined kinematic viscosities of simple triacylglycerols [trilaurin, trimyristin (MMM), tripalmitin (PPP), tristearin (SSS), triolein (OOO), and trilinolein (LiLiLi) were correlated to a modified Andrade-type equation. The constants for the modified equation were derived for each simple triacylglycerol. The method was also used to estimate the viscosity of mixed triacylglycerols [1,2-dimyristoyl-3-palmitoyl (MMP), 1,2-dioleoyl-3-palmitoyl (OOP), 1,2-dimyristoyl-3-oleoyl (MMO), and 1,2-dipalmitoyl-3-oleoyl (PPO)], binary triacylglycerol mixtures (PPO/OOP, PPP/SSS, and OOO/SSS of different portions), and three types of vegetable oils [refined, bleached, and deodorized palm oil; cocoa butter; and canola oil] by applying modified Kay’s rule utilizing the simple triacylglycerol constants derived earlier. In all cases, the estimated values for liquid viscosity were compared with experimental values determined in this work and with previous work from the literature. When applied to vegetable oils, the method requires knowledge of their triacylglycerol composition. Despite its simplicity, the method gives a reasonable estimate. The method may be used to predict the viscosity of different blends of vegetable oils, and the accuracy is expected to increase when more experimental data on simple triacylglycerols become available.     

Optimal operation conditions for bio-hydrogen production from duckweed

Hydrogen gas is an ideal alternative fuel and produces no greenhouse gases. The dark fermentation is considered the most attractive for production of biohydrogen gas. Duckweed is an aquatic plant that has treatment properties and can be used as biomass for the fermentation to produce eventually bio-hydrogen production. This study investigated the impact of different temperature, pH, and substrate concentration on bio-hydrogen production by fermentation. Experimental tests were run flask studies in serum bottles by aim of determing the optimal operating conditions to maximize bio-hydrogen production. According to the results, concentration loading in the range 30–40 g DW/L was determined as suitable for efficient bio-hydrogen production. Different temperatures on bio-hydrogen production were compared, and 35°C was observed to be more effective than others. Moreover, pH 5.5 was determined as the optimal pH value.     

Utilization of waste marble dust as an additive in cement production

In this experimental study, the usability of waste marble dust (WMD) as an additive material in blended cement has been investigated. For this purpose, waste marble dust added cements (WMDCs) have been obtained by intergrinding WMD with Portland cement clinker at different blend ratios: 2.5%, 5.0%, 7.5% and 10% by weight. 40 × 40 × 160 mm mortar prisms have been produced with the obtained cements. Strength tests have been carried out on mortar specimen at 7, 28, and 90 days. WMDCs have been compared to each other as well as to control cements of CEM I and CEM II with respect to their physical, chemical and mechanical properties. Obtained results showed that WMDCs conform to EN 197-1 standard and thus 10% WMD can be used as an additive material in cement manufacturing.     

Comparison of antioxidant capacity and phenolic composition of peel and flesh of some apple varieties

BACKGROUND: Apples contain a large concentration of phenolic compounds, dependent on factors such as cultivar, harvest, storage conditions, and processing. This study aims to identify the essential phenolic compounds present in various apple varieties, to measure their total antioxidant capacity (TAC) with the CUPRAC (cupric ion reducing antioxidant capacity) and ABTS (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonate)) methods, and to correlate their TAC values with HPLC findings. RESULTS: The order of TAC (mmol Trolox g^?1 fresh weight) of apple peels determined with the CUPRAC method was: Granny Smith > Amasya > Sky Spur > Ervin Spur > King Luscious ≥ Arap Kizi ≥ Lutz Golden. The theoretically calculated TAC values of HPLC‐quantified compounds, with the aid of the combined HPLC‐CUPRAC method, accounted for 18.4–33.5% of the experimentally observed CUPRAC capacity of peel extracts and 19.5–56.3% of flesh extracts, depending on apple variety. CONCLUSION: In synthetic samples of apple antioxidants, the CUPRAC‐TAC values of constituents, identified and analyzed by HPLC, proved to be additive, enabling measurement of the cooperative action of antioxidants using the proposed methodology. Apple peel showed higher contents of phenolics and therefore higher TAC than apple flesh, confirming the health benefit of the consumption of apples together with peel. © 2012 Society of Chemical Industry