Influence of Drying Temperature and Rehydration on Selected Textural Properties of Carrots

Cubes of carrots dried at 60, 70, 80, and 90°C were rehydrated up to 180 min at 20°C and up to 10 min at 95°C. Kinetics of cutting strength were determined for the samples soaked at 95°C. Compression stress relaxation behavior of the samples was studied on carrots rehydrated at 20 and 95°C. Kinetics of cutting strength were satisfactorily described by means of a first-order kinetic model. The compression stress relaxation of carrots was analyzed using five element Maxwell and empirical Peleg models. Both of the models were found to be appropriate for characterizing viscoelastic properties of dried and rehydrated carrot cubes. The results indicated that the use of low drying temperatures was suitable for preserving the quality attributes of carrots after rehydration, and drying air temperature of 60°C was chosen as the most appropriate for hot air processing of carrots.     

Costs and Benefits of Smart Grids on Liberalized Markets

The discussion about smart grid(SG) implementation is mostly focused on pilot projects.These projects are necessary for mapping of particular technical devices of advanced metering management(AMM) which is needed for successful SG and whole functional SG system operation.According to our opinion,for the next step of SG implementation,the participation of effective market design would be quite necessary.In other words,pilot project which is operated regardless to the market conditions and special SG tariff is incomplete and could be irrelevant for further evaluation of feasibility.With regard to above mentioned facts,the detailed cost-benefit-analysis(CBA) is needed to establish the correct methodology for evaluation of SG implementation effectiveness.Related aspects are mentioned and discussed in this paper,in which the particular cost and benefits as well as feedback that occurs as the reaction on implementation are summarized and quantified.     

Multiple defect core photonic crystal fiber with high birefringence induced by squeezed lattice with elliptical holes in soft glass

We present a dual mode, large core highly birefringent photonic crystal fiber with a photonic cladding composed of elliptical holes ordered in a rectangular lattice. The fiber is made of borosilicate glass and has a regular set of elliptical holes with an aspect ratio of 1.27 and a filling factor near 0.5. The group birefringence (G) and effective mode area were measured at 1550 nm for the fundamental mode and were found to equal 2 × 10^?4 and 20 μm² respectively. We discuss the influence of structural parameters including the ellipticity of the air holes and the aspect ratio of the rectangular lattice on the birefringence and on the fundamental and second modes of the fiber.     

Electro-thermal analysis and optimization of edge termination of power diode supported by 2D numerical modeling and simulation

High reliability and performance of power semiconductor devices depend on an optimized design based on a good understanding of their electro-thermal behavior and of the influence of parasitic components on their operation. This leads to the need for electro-thermal 2/3-D numerical modeling and simulation in power electronics as an efficient tool for analysis and optimization of device structure design and identification of critical regions. In this paper we present an analysis and geometry optimization of a high power pin diode structure supported by advanced 2-D mixed mode electro-thermal device and circuit simulation. Lowering of the operation temperature by better power management and heat dissipation due to an optimized structure design will allow withstanding higher current pulses and suppressing the damage of the analyzed structure by thermal breakdown.     

Calcium Containing Silicate Mixed Oxide-Based Heterogeneous Catalysts for Biodiesel Production

A series of calcium containing silicate mixed oxide materials has been developed for biodiesel production. It has been shown that these materials can catalyze transesterification reactions from feedstocks with various fatty acid contents. However, their reaction kinetics for biodiesel synthesis was very slow compared to that of homogeneous-catalyst-catalyzed reactions. Herein, we report fast-reacting solid catalysts for biodiesel production. Two types of materials have been developed: a non-porous and an anionic-surfactant-templated catalysts. Compared to previously reported transesterification reaction by mesoporous calcium containing silicate catalysts, the reaction rates from both families were much faster. In addition, both the preparation time of catalysts and the cost of preparation were significantly reduced. Details in material synthesis and its effect on catalysis are discussed.     

Boron in seawater and methods for its separation — A review

The seawater reverse osmosis (SWRO) membrane desalination process is a relevant and reliable technology for desalination of seawater. However, some serious limitations had recently been discovered during field practice, among them the boron problem seems to have a critical meaning. According to the WHO regulations, the boron concentration should be reduced to less than 0.5 mg/L for drinking water. It was also reported that, this limit is rarely reached for conventional reverse osmosis desalination plants equipped with commercially available membranes. This paper reviews the extensive published literature on separation methods of boron removal from seawater.     

A benign synthesis of alane by the composition-controlled mechanochemical reaction of sodium hydride and aluminum chloride

Solid-state mechanochemical synthesis of alane (AlH₃) starting from sodium hydride (NaH) and aluminum chloride (AlCl₃) has been achieved at room temperature. The transformation pathway of this solid-state reaction was controlled by a stepwise addition of AlCl₃ to the initial reaction mixture that contained sodium hydride in excess of stoichiometric amount. As in the case of previously investigated LiH–AlCl₃ system, complete selectivity was achieved whereby formation of unwanted elemental aluminum was fully suppressed, and AlH₃ was obtained in quantitative yield. Reaction progress during each step was investigated by means of solid-state NMR and powder X-ray diffraction, which revealed that the overall reaction proceeds through a series of intermediate alanates that may be partially chlorinated. The NaH–AlCl₃ system presents some subtle differences compared to LiH–AlCl₃ system particularly with respect to optimal concentrations needed during one of the reaction stages. Based on the results, we postulate that high local concentrations of NaH may stabilize chlorine-containing derivatives and prevent decomposition into elemental aluminum with hydrogen evolution. Complete conversion with quantitative yield of alane was confirmed by both SSNMR and hydrogen desorption analysis.     

The influence of defects on strength of ceramics modeled with Movable Cellular Automata

Ceramics is widely used material in engineering practice because of its great strength, high heat resistance and low density. The strength is a subject of our investigations. It can be significantly decreased by small defects, such as scratches, inclusions, pores, and surface roughness. The aim of this article is to demonstrate an application of the Movable Cellular Automata (MCA) method in 3D to simulate static compression test of ceramic material with various type of defects. As results we can observe damage evolution and cracks propagation leading to sample failure.