Grafting of poly(acrylic acid) on polyamide yarn

Graft copolymerization of acrylic acid onto PA6 yarn was examined in this study. Prior to the grafting process, the fibers were activated with a benzene solution of benzoyl peroxide. Next, the fibers were put into a bath containing acrylic acid, a dispersing agent, and the activator of reaction. The effects of the main process parameters and auxiliary additives on the degree of grafting, quantity of the homopolymer formed during grafting, effectiveness of grafting, extent of conversion, and grafting ratio were determined. Using calculation factors such as the reaction efficiency, the extent of reaction, and the ratio of grafting, the conditions of grafting were found that made possible the reduction or elimination of the by‐product. Also determined were the influence of the degree of grafting on the moisture sorption and the swelling of modified fibers. In addition, the value of apparent activation energy was calculated (49.123 kJ/mol). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1914–1919, 2001     

SOLID PHASE EXTRACTION FOR PRECONCENTRATION AND SEPARATION OF SELENIUM SPECIES

ABSTRACT

There is sufficient evidence today that selenium is both an essential and toxic element for animal and man. This review article intends to show the involvement of selenium in the environment and in biology. Attention is paid to its occurrence, distribution, sampling and storage and also recent developments for selenium determination reported in analytical literature. Special emphasis is placed on the application of solid sorbents for preconcentration and separation of inorganic and organic selenium species. Published data for these procedures are critically discussed.     

SELECTIVITY OF RESINS WITH GUANIDYL GROUPS TOWARDS DICYANOAURATE ANIONS

ABSTRACT

Resins having two types of ligands: guanidine and aminoguanidine on copolymers of vinylbenzyl chloride (VBC)/ methyl methacrylate (MM)/ divinylbenzene (DVB) and on styrene (S)/DVB have been investigated in respect to their selectivity towards dicyanoaurate anions Resins coded CH and CP displayed high selectivity and sorption of gold from its diluted solution. They sorbed 10 - 11?mg of gold/g and dicyanoaurate distribution coefficient reached 1890 and 2290, respectively. Resins have the following selectivity order when sorption was carried out from solution of 5.08?mg Au/dm³: resin U-BIS Zn>Ag>Au>Cu; resin CP Au>Zn»Cu»Ag; resin CH Au>Zn=Ag»Cu. Resins have weak affinity towards iron complexes.     

Eu-Doped BaTiO3 Powder and Film from Sol-Gel Process with Polyvinylpyrrolidone Additive

Transparent BaTiO₃:Eu³⁺ films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO₃:Eu³⁺ films ~500 nm thick, crystallized after thermal treatment at 700 ºC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu³⁺ doped BaTiO₃.     

Concentrated Water Solution of Salts as Solvents for Reactions of Carbohydrates. Part 1: Reactions of Glucose Promoted by Concentrated Solutions of Alkaline and Alkaline Earth Metal Salts

Saturated water solutions of selected alkaline and alkaline earth metal salts have been studied whether or not they catalyze the formation of levulinic acid from glucose. The most active was a solution of magnesium chloride. Activity was further increased in the system (MgCl₂+H⁺). We observed complete inhibition of this reaction by NO₃⁻. Contrary to the generally accepted opinion that formation of hydroxymethylfurfural is only H⁺ catalyzed, we observed activity of the system formed from MgO and MgCl₂ when one starts from glucose. (MgCl₂+ MgO) in water is alkaline.     

The potential for large-scale savings from insulating residential buildings in the EU

Energy used in buildings is responsible for more than 40% of energy consumption and greenhouse gas (GHG) emissions of the EU and their share in cost-efficient GHG mitigation potentials is estimated to be even higher. In spite of its huge savings potential of up to 80%, achievements are very slow in the building sector and much stronger political action seems to be needed. One important step in this direction has been the recast of the Energy Performance of Buildings Directive (EPBD) in autumn 2009. However, strong national implementation including powerful packages of flanking measures seems to be crucial to really make significant progress in this important field. In order to directly improve political action, we provide a differentiated country-by-country bottom up simulation of residential buildings for the whole EU, Norway, Iceland, Croatia and Liechtenstein. The analysis provides a database of the building stock by construction periods, building types, as well as typical building sizes. It includes a simulation of the thermal quality and costs of the components of the building shell for new buildings as well as the refurbishment of the existing building stock. Based on this differentiated analysis, we show in detail what would be needed to accelerate energy savings in the building sector and provide a more precise estimate of the potentials to be targeted by particular policies. We demonstrate, e.g. that the potential of building codes set via the EPBD would be located mainly in those countries that already have quite stringent codes in place. We show as well the high relevance of accelerating refurbishments and re-investment cycles of buildings. By providing a clear estimate of the full costs related to such a strategy, we highlight a major obstacle to accelerated energy-efficient building renovation and construction.     

Experimental and simulation studies of primary vacuum freeze-drying process of random solids at microwave heating

This paper concerns experimental and theoretical studies of freeze-drying process at microwave heating. Two kinds of random solids were dried: material which are assumed to have no internal porosity (ground glass), as well as one containing internal porosity (Sorbonorit 4 activated carbon). Formulated one-dimensional two-region model of freeze-drying process at microwave heating takes into account unknown a priori sublimation temperature T_s(t) and mass concentration of water vapor C_s(t) at moving ice front. Steady capacity of internal heat source is correlated with electric field strength E and dissipation coefficient K(T) in both regions of the material to be dried. Linear temperature dependency of dissipation coefficient is assumed and described by two regression parameters: μ_1i and μ_2i for dry (i = I) and frozen (i = II) bed, respectively. A correlation between both measured and calculated temperatures of the sample and actual electric field strength was observed. Fairly good agreement between experimental and simulated results was stated.     

Raspberry seed extract effect on the ferroxidase activity of ceruloplasmin isolated from plasma

In this study, the effect of the raspberry seed extract (RSE) on the ferroxidase activity of ceruloplasmin (Cp) isolated from healthy male subject serum was analyzed. The ferroxidase activity of Cp was determined by spectrophotometry using Fe(II) – histidine complex and ferrozine as a chromogenic reagent. The ferroxidase activity of ceruloplasmin was demonstrated in dose-dependent way within the range 22–66 μg/ml. The effect of RSE on Fe(II) concentration, measured as the decrease of Fe(II) concentration in samples and expressed as ΔFe(II), was found to be a dose-dependent within the range 1.20–51.56 μg dm/ml. The ferroxidase activity of Cp was influenced by the RSE within its studied range. However, the addition of the highest concentration of RSE (51.56 μg dm/ml) to the sample containing the highest level of Cp (66 μg/ml) did not affect its ferroxidase activity. It may be suggested that the competition for Fe(II) as the substrate limits the effect of RSE on Cp activity and causes no further changes in Fe(II) elimination.     

Recommendation on modelling of solar energy incident on a building envelope

It is important to know how to design a building to meet seasonally varying energy needs. In high latitude countries in winter the demand for space heating is high and a building envelope should receive maximum incident solar energy. On the other hand, in summer, walls and roofs exposed to incident solar radiation usually require shading to avoid too much solar gain. Data on solar energy availability are crucial for good building design. However, it is important how the availability of solar radiation is determined. An important aim of the paper presented is to give some results of a comparative analysis of two basic sky models, isotropic: Hottel–Woertz–Liu–Jordan and anisotropic: the HDKR, Hay–Davies–Klucher–Reindl, to recommend one of these models for determination of solar energy availability on a building envelope and to formulate the energy balance of a building. Differences between results obtained from both models increase with the slope of exposed surfaces. The biggest differences (12–15%) are evident for vertical south surfaces, especially in summer. The simplified isotropic sky model is not recommended for evaluation of solar radiation availability on the building envelope. Underestimation of solar gains can lead to the selection of an unsuitable concept and construction of a building and result in poor indoor thermal comfort, i.e. overheating of rooms in summer.