Isolation, modification and characterization of soluble arabinoxylan fractions from rye grain

Because of the positive role of arabinoxylans and especially their water-soluble fractions in establishing bread properties, it seems reasonable to use them as natural bread improvers. In this work, an adequate isolation procedure of water-soluble arabinoxylans from rye grain with efficient purification steps is presented, delivering 2.9?% yield from wholemeal with a content of arabinoxylan of approximately 70?% and an arabinose/xylose ratio of 0.7. Furthermore, soluble arabinoxylans were modified by enzymatic hydrolyses, cross-linking with peroxidase/H₂O₂ treatment and combination of both for developing preparations applicable for bread making with different quality profiles. Additionally, a detailed analysis of chemical composition and molecular dimension was carried out by HPLC, SEC, HPSEC and viscosity measuring. The preparation after cross-linking showed considerably higher molar mass values, lower solubility and higher viscosity with high Huggin??s constant compared to the not modified sample. Otherwise, the combination of enzymatic hydrolysis and cross-linking resulted in the formation of arabinoxylan preparations with only slight degree of cross-linking and properties comparable with the only hydrolyzed sample.     

Contribution of small‐scale wind generation to primary frequency control

The connection of small‐scale embedded generation to the grid may influence the frequency and voltage stability of the power system. A load‐frequency control technique for systems with high penetration of small‐scale wind generation is proposed. The proposed controller has been successfully implemented and tested using PSCAD/EMTDC (PSCAD Power System Simulation, HVDC Research Centre, Manitoba, Canada). In this study, the impact of small‐scale wind turbines on frequency stability of the system is studied in detail. This study shows that large penetration of small‐scale wind turbines with load and frequency has a significant impact on the stability and security level of electrical network. Copyright © 2012 John Wiley & Sons, Ltd.     

Organizational vs. personal social capital in scientists' performance: A multi-level network study of elite French cancer researchers (1996-1998)

Scientometrics - The difference between individual social capital and organizational (or corporate) social capital has been an important topic of research in sociology during the past decade. The...     

Low-temperature anisotropy of thermal conductivity of tin single crystals doped with zinc

The thermal conductivity of tin single crystals with zinc admixtures has been measured in the temperature range 3.5–25 K for concentrations up to 0.1 wt%. The anisotropy of thermal conductivity for two orientations, [001] and [010], has been determined. It was found that the influence of zinc admixture on the thermal conductivity anisotropy is of a complex, temperature-dependent character.Nomenclature T ₁ T ₂ Temperature differences in the specimen - Thermal conductivity coefficient - W Thermal resistivity - A, B, C Constants in Eq. (1) - T Temperature - ^th Residual electrical resistivity calculated from W-F law - ₀ Residual electrical resistivity from measurements - L ₀ Lorenz constant - _th Anisotropy coefficient of thermal conductivity - _el Anisotropy coefficient of electrical conductivity - c Admixture concentration     

Data-driven and tool-supported elicitation of quality requirements in agile companies

Software Quality Journal - Quality requirements (QRs) are a key artifact needed to ensure the quality and success of a software system. Despite their importance, QRs rarely get the same degree of...     

Particle formation in supercritical fluids—Scale-up problem

The process of antisolvent precipitation of particles, termed solution enhanced dispersion by supercritical fluids (SEDS™), is applied to precipitate the model drug, paracetamol, from ethanol solutions. In the SEDS process the substrate solution is quickly mixed in a mixing chamber of the coaxial two-component nozzle with an antisolvent, represented in this case by the supercritical CO₂. Resulting partially mixed, highly supersaturated solution is introduced into the precipitation vessel as a jet, which generates intensive circulation of residual fluids that dilute the fresh supersaturated solution. Nucleation starts in the nozzle chamber, whereas particle growth completes the process in the precipitation vessel. The process is carried out above the mixture critical pressure; the antisolvent is thus completely miscible with the solvent. Under such conditions the macro-, meso-, and micro-mixing processes can affect the particle size distribution (PSD) and should be considered when the process is scaled up. Scaling up considerations of the precipitation process are based on scale-up rules, CFD simulations and experimental data for paracetamol precipitation. In simulations the model presented earlier (Ba?dyga et al., 2004) that is based on the population balance equation and CFD modelling of compressible flow processes is applied. Results of experimental investigations and numerical simulations are applied to verify scale-up strategies for the SEDS processes.     

The effect of circulating fluidized bed boiler load on the emission of mercury

The paper deals with the determination of mercury balance for a hard coal-fired circulating fluidized bed boiler operated at various loads (i.e. 100%, 75% and 50% of the Maximum continuous rating, MCR). The research was focused on the determination of the mercury balance by providing data on Hg content in fuel, limestone sorbent, and in the combustion by-products (fly ash and bottom ash). Furthermore, the concentration of mercury in the flue gas in two zones i.e. upstream and downstream the electrostatic precipitator (ESP) were also determined in order to assess the effectiveness of the ESP in mercury reduction. For the calculation of the Hg balance both gaseous mercury species, Hg⁰, and oxidized mercury, Hg²⁺, were taken into consideration.The results indicated that over 95% of the mercury was fed into the boiler system with coal and just less than 5% with limestone used for ‘dry’ desulfurization of the flue gas. As for the boiler output, very high mercury content was determined in the fly ashes, while just a minor part (a few percent of the total mercury input) was found in the bottom ashes. The shares of Hg⁰ and Hg²⁺ mercury were affected by boiler load.     

Selective Synthesis of Polyoxyethylene–Polyoxypropylene Block Copolymer (Poloxamer) Fatty Acid Monoesters Over Homogeneous Organotin Catalyst

The synthesis of selected polyoxyethylene–polyoxypropylene block copolymer (poloxamer) fatty acid monoesters is presented. Organotin homogeneous catalyst Sn bis(2‐ethylhexanoate) effectively catalyzed the esterification reaction of (EO)–(PO)–(EO) block copolymer (poloxamer) with fatty acids. The reaction proceeded in high yield and high selectivity to monoesters. Content of diesters in final products was below 1 wt%. The new protocol opened up a high yield and high selective method for the synthesis of poloxamer fatty acid monoesters. These products are potentially interesting for industrial applications, e.g. in lubricants, cosmetics and, in particular, as potential emulsifying agents compatible with hydrocarbon bases, such as paraffin.     

Dynamical changes during composite milling: recurrence and multiscale entropy analysis

Fluctuations describing chatter in the milling process of a composite material were analyzed using statistical, recurrence, and multiscaled entropy analyses. Through changing the rotational speed, we observed the appearance of chatter vibrations and signatures of intermittency. The corresponding characteristic change of recurrences could be used to invent a new efficient control procedure of milling. The workpiece was prepared from nonuniform material based on epoxy-polymer matrix composite reinforced by carbon fibers.