Structural,mechanical, and antibacterial features of curcumin/polyurethane nanocomposites

Various types of bacteria inhabit many surfaces thus causing problems which can have very strong impact on human health. Here we present a study of photophysical, mechanical, and antibacterial properties of curcumin/polyurethane nanocomposites prepared by swell-encapsulation-shrink method. The prepared nanocomposites have been characterized for degree of swelling, surface morphology, mechanical properties, chemical contents, photoluminescence, hydrophobicity, potentials for singlet oxygen generation, and antibacterial activity. Dynamic mechanical analysis has shown slight changes of glass temperature of curcumin/polyurethane nanocomposites due to blue light irradiation. It was found that nanocomposites have very strong photoluminescence, become photoactive upon blue light irradiation at 470 nm and generate singlet oxygen. Conducted antibacterial tests have shown very strong activity of these nanocomposites especially toward Escherichia coli. These bacteria strains have been eliminated completely only after 1 h irradiation by blue light. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47283.     

Epidemiology of end‐stage renal disease and hemodialysis treatment in Serbia at the turn of the millennium

The study presents the epidemiological features of patients treated with renal replacement therapy (RRT) in Serbia from 1997 to 2009 and compares the results of hemodialysis treatment in 1999 and 2009. Epidemiological data were obtained from the National Registry of RRT patients and data on hemodialysis treatment from special surveys conducted in 1999 and 2009. Within the period 1997–2009 the incidence of patients on RRT increased from 108 to 179 per million population (pmp), prevalence rose from 435 to 699 pmp, while mortality rate fell from 20.7% to 16.7%. The frequency of patients with glomerulonephritis decreased, while that of patients with diabetes and hypertensive nephropathy increased. In late 2009 there were 5208 patients receiving RRT in Serbia. Within the examined period new hemodialysis and reverse osmosis equipment were purchased, high‐flux dialyzers with synthetic membranes were increasingly used and the number of patients receiving hemodiafiltration increased to 17.6%. Kt/V greater than 1.2 was recorded in 16% of the patients in 1999 but 52% in 2009. Options for correction of anemia and mineral disorders have also improved. The percentage of patients with HbsAg (13.8% vs. 4.8%) as well as anti‐hepatitis C virus antibodies positive patients (23.2% vs. 12.7%) was significantly lower in 2009 than in 1999. Both the incidence and prevalence of RRT patients in Serbia are rising continuously, while the mortality rate is falling. More favorable conditions for dialysis treatment have brought about significant improvement in the results over the last 10 years.     

The influence of genotypic variation in protein composition on emulsifying properties of soy proteins

This study describes the relationship between the emulsifying properties of soybean proteins and their composition, i.e., glycinin (11S) and β-conglycinin (7S). Twelve investigated soybean genotypes showed significant differences in storage protein composition. The β-conglycinin concentration positively correlated with extractable soluble protein content, which was positively correlated with protein extractability. These data suggest that the level of β-conglycinin has a positive influence on protein extractability. The emulsion activity index (EAI) was strongly and positively correlated with the 11S∶7S ratio and strongly and negatively correlated with the concentration of β-conglycinin. The emulsion stability index (ESI) showed a moderate positive correlation with the monomeric form of glycinin and a strong positive correlation with the ratio of the monomeric to dimeric form of glycinin. No association was evident between ESI and EAI. Also, no relationship was found between ESI or EAI and extractability. Based on these data, it appears that the 11S∶7S ratio strongly reflects the ability of soybean proteins to form emulsions, whereas the ratio of the two different forms of glycinin may be crucial factors for the stability of soybean protein emulsions. Thus, understanding the relationship between protein composition and functionality could be useful for further improvement of functional behavior of soy proteins in food systems.     

Modified softwood sawdust as adsorbent of heavy metal ions from water

The sawdust of deciduous softwood-poplar, and coniferous softwood-fir, have been found to possess some adsorption capacities for heavy metal ions. Their adsorption capacities can be increased by previous treatment with a sodium hydroxide solution. Adsorption capacities of alkali modified adsorbents were higher than for unmodified ones from 2.5 to 5 times for copper ions, and about 15 times for zinc ions. Also, for modification can be used solution of sodium carbonate, but that alkaline solution is less efficient than sodium hydroxide solution. The 1% sodium hydroxide solution is suggested for modification of softwood sawdust. It was established that the ion exchange is not only adsorption mechanism, than microprecipitation of metal-hydroxide in the pore liquid was happened, too. At the same time, the leaching of organic matters from modified softwood sawdust were less than from unmodified ones for about 7% for poplar and 23% for fir.     

Decolorization of reactive textile dyes using water falling film dielectric barrier discharge

Decolorization of reactive textile dyes Reactive Black 5, Reactive Blue 52, Reactive Yellow 125 and Reactive Green 15 was studied using advanced oxidation processes (AOPs) in a non-thermal plasma reactor, based on coaxial water falling film dielectric barrier discharge (DBD). Used initial dye concentrations in the solution were 40.0 and 80.0 mg/L. The effects of different initial pH of dye solutions, and addition of homogeneous catalysts (H₂O₂, Fe²⁺ and Cu²⁺) on the decolorization during subsequent recirculation of dye solution through the DBD reactor, i.e. applied energy density (45-315 kJ/L) were studied. Influence of residence time was investigated over a period of 24 h. Change of pH values and effect of pH adjustments of dye solution after each recirculation on the decolorization was also tested. It was found that the initial pH of dye solutions and pH adjustments of dye solution after each recirculation did not influence the decolorization. The most effective decolorization of 97% was obtained with addition of 10 mM H₂O₂ in a system of 80.0 mg/L Reactive Black 5 with applied energy density of 45 kJ/L, after residence time of 24 h from plasma treatment. Toxicity was evaluated using the brine shrimp Artemia salina as a test organism.     

Infrared analysis of Macedonian mushroom dietary fibre

The existing confusion in the terminology and composition of the mushroom dietary fibre literature data induced us to analyze simultaneously the chemical constitution of various dietary fibre isolates obtained from numerous mushroom samples. For that purpose, in 53 kinds of edible Macedonian mushrooms total dietary fibre was isolated by two parallel methods intended for material of plant and animal origin. With the aid of infrared spectroscopy the chemical constitution of the both isolated components was also investigated. The infrared spectra of the total dietary fibre isolates, obtained according to both applied methods, were similar and close to chitin. In all spectra cellulose is missing.     

The effect of fillers on relaxation phenomena of vulcanized styrene–butadiene elastomers

Standard recipe mixtures, based on styrene/butadiene rubber SBR 1500 and oil-extended SBR 1712, with varying amounts of carbon black, silica, or kaoline fillers were prepared and the stress relaxation curves of vulcanized samples were determined. The measurements were restricted to slow relaxation phenomena, observed after 50% initial elongation. Three λ-processes and a fourth ?-process, existing only in filled rubbers, were observed. The relaxation times and activation energies, determined graphically, reflect the amount and activity of the fillers. All relaxation times are lower for filled vulcanizates and decrease with increasing temperature; however, the type of filler does not affect the activation energy. The higher parameters observed for the ?-processes are discussed in terms of filler particle mobilities and rearrangements and of filler/rubber contact layer phenomena. © 1994 John Wiley & Sons, Inc.