Polyurethane foams with the contribution of products of hydroxyalkylation of N,N′‐bis(2‐hydroxyalkyl)oxamides with alkylene carbonates—obtaining and properties

In the reactions of N,N′‐bis(2‐hydroxyethyl)oxamide (BHEOD) with an excess of ethylene carbonate (EC) and N,N′‐bis(2‐hydroxypropyl)oxamide (BHPOD) with an excess of propylene carbonate (PC), the hydroxyethoxy and hydroxypropoxy derivatives of oxamide (OD) were obtained, respectively, distinguished by an increased thermal stability. First time, these derivatives were used as polyol components to obtain foamed polyurethane plastics with the contribution of 4,4′‐diisocyanate diphenylmethane (MDI). The rigid polyurethane foams of a slight water uptake, good stability of dimensions, enhanced thermal stability, and compression strength were obtained. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Application of the homotopy perturbation method for the solution of inverse heat conduction problem

This paper deals with an application of the homotopy perturbation method for the solution of inverse heat conduction problem. This problem consists in the calculation of temperature distribution in the domain, as well as in the reconstruction of functions describing the temperature and heat flux on the boundary, when the temperature measurements in the domain are known. Examples illustrating discussed application and confirming utility of this method in such a type of problem was also presented.     

Functionalization of gold-coated carbon nanotubes with self-assembled monolayers of thiolates

Multi-walled carbon nanotubes (CNT) were synthesized by chemical vapor deposition using Co–Fe as a catalyst and ethylene as a carbon source. Afterward, a simple method combining wet-chemistry and chemical reduction was used to prepare carbon nanotube/gold material (CNT/Au). Pristine nanotubes and CNT/Au were characterized by transmission electron microscopy micrographs. It appeared that gold formed nanoparticles on CNTs endings and their sidewalls. Further functionalization was carried out by using thiols of different chemical properties and molecule sizes. Thiols formed self-assembled monolayer on gold surface that led to formation of CNT/gold/thiol-functionalized material. The amounts of chemisorbed thiols were measured by elemental analysis and thermogravimetry.     

Radiation sterilized bone response to dynamic loading

Allogeneic bone grafts are used on a large scale in surgeries. To avoid the risk of infectious diseases, allografts should be radiation-sterilized. So far, no international consensus has been achieved regarding the optimal radiation dose. Many authors suggest that bone sterilization deteriorates bone mechanical properties. However, no data on the influence of ionizing radiation on bone dynamic mechanical properties are available. Bovine femurs from 2-year old animal were machine cut and irradiated with the doses 10, 15, 25, 35, 45 and 50 kGy. Dynamic mechanical analysis was performed at 1–10 Hz at the temperature range of 0–350 °C in 3-point bending configuration. No statistically significant differences in storage modulus were observed. However, there were significant decreased values of loss modulus between the samples irradiated with doses of 10 (↓14.3%), 15, 45 and 50 kGy (↓33.2%) and controls. It was stated that increased irradiation dose decreases the temperature where collagen denaturation process starts and increases the temperature where the collagen denaturation process finishes. It was shown that activation energy of denaturation process is significantly higher for the samples irradiated with the dose of 50 kGy (615 kJ/mol) in comparison with control samples and irradiation with other doses (100–135 kJ/mol).     

Diet with linseed oil and organic selenium yields low n‐6/n‐3 ratio pork Semimembranosus meat with unchanged volatile compound profiles

The aim of this was to improve n‐6/n‐3 ratio without affecting the volatile compounds profiles of pork. Different feeding strategies were designed for 60 Polish Landrace pigs with the goal to enhance the health attributes of Polish pork. Composition, colour, hardness, fatty acid contents and volatile compound profiles of the semimembranosus muscles were determined. Results showed that with the basic diet with the addition 3% of linseed oil, 100 mg kg^?1 of vitamin E and 1 mg kg^?1 of organic selenium, the level of polyunsaturated fatty acids (PUFA) in the meat samples was increased by 26% (P ≤ 0.05) as compared to the control. Principal component analysis (PCA) demonstrated that the aroma profile of semimembranosus muscles from pigs fed with the diet supplemented with 3% of linseed oil and 1 mg kg^?1 of organic selenium was close to that of control. Results demonstrated that healthy functional meats could be produced by designing feeding strategies.     

Evaluation of electrochemical hydrogenation and corrosion behavior of LaNi5-based materials using galvanostatic charge/discharge measurements

A detailed thermodynamic analysis of galvanostatic −i/+i characteristics of epoxy resin bonded, LaNi₅ powder based electrodes enables not only alloy hydrogenation ability but also oxidation susceptibility of their constituents to be determined. It is shown that electrode cycling is prone to oxidation of nickel during discharging process, however, the NiO/Ni equilibrium is reversible and nickel oxides undergo reduction during charging. Similar behavior exhibits bismuth as Ni partial substitute. The way of determining alloy constituent oxidation/reduction times as well their corrosion rate in 6 M KOH is presented. The effects of substitution of 20 at% of nickel by Bi or Zn on hydrogen capacity, corrosion behavior and surface development are discussed. It is shown that multiphase LaNi₄Bi alloy possesses much worse whereas monophase LaNi₄Zn alloy possesses clearly better hydrogen absorption properties as compared with LaNi₅ reference. The plots of charge curves allow to distinguish processes of atomic hydrogen absorption and evolution of molecular H₂ for the tested alloys.     

Release of free ferulic acid and changes in antioxidant properties during the wheat and rye bread making process

Changes in the free ferulic acid (FFA) contents and antioxidant properties during bread making processes were determined. Experimental breads were produced from whole meal and white wheat and rye flours, and fermented using either baker’s yeast or sourdough starter. Sourdough fermented bread contained the highest content of FFA. Release of occurred mainly during dough fermentation. A further increase in the ferulic acid content in the bread crumb and a decrease in the crust was observed. Total antioxidant properties of sourdough bread, defined as the sum of lipophilic and hydrophilic compound activities, were significantly (p<0.05) higher than for yeast bread. Sourdough bread contained more methanol soluble phenolic compounds, proteins, tocochromanols, and oxidized products of fatty acids than yeast bread. The equilibrium between the anti- and pro-oxidative compound contents resulted in similar antioxidant properties for bread using both types of fermentation, and to results observed for the flour used for baking.     

Effect of glycerol and dihydroxyacetone concentrations in the culture medium on the growth of acetic acid bacteria Gluconobacter oxydans ATCC 621

Bacteria of the species Gluconobacter oxydans are applied in the industrial production of dihydroxyacetone (DHA) via glycerol oxidation. The major problem of this biotransformation involves process inhibition by substrate and/or product. Improper initial concentration of glycerol and increasing DHA concentration may inhibit the metabolic activity of bacterial cells and impede further course of the reaction. An attempt was, therefore, undertaken in this study to determine which concentrations of glycerol (30, 50, 70, 100 g L^?1) and DHA (10–100 g L^?1) may inhibit the growth of acetic acid bacteria of G. oxydans ATCC 621 species. Cultures of this strain were run in the Bioscreen C MBR apparatus on experimental culture media with various initial concentrations of glycerol and DHA. Analyses were also carried out to examine the impact of pH (5.0, 7.0, 8.0) of glycerol-containing culture media on cell growth of the analyzed strain G. oxydans. None of the applied substrate concentrations was inhibiting cellular divisions of G. oxydans bacteria. The initial glycerol concentrations that enabled rapid cellular divisions reached 50 g L^?1 in the medium with pH 5.0 (coefficient of specific growth rate μ = 0.0550) and 70 g L^?1 in the medium with pH 7.0 (μ = 0.0556). DHA was shown to inhibit the mitotic activity of G. oxydans bacteria even at low concentrations (20–30 g L^?1), whereas at the concentration of 70 g L^?1, it made cell divisions impossible. The applied pH values of the culture media did not inhibit the growth of G. oxydans strain.