Is melatonin an antioxidant?

The ever increasing understanding of oxygen radical-linked diseases, including the biological process of aging, has stimulated general interest in modulating these biological events. Among the many natural compounds recognized to exert protection against oxidative stress, melatonin was reported to have antioxidant properties in addition to its known hormonal activities. The present contribution critically reviews the published biochemical data on the antioxidant properties of melatonin. Furthermore, the suggested retardation effect of melatonin on senescence, which is based on the "free radical theory of aging", is also critically evaluated.     

Silver content of wild-grown mushrooms from Northern Poland

Wild-grown and mostly edible species of higher mushrooms collected in 1989–1992 from the districts of Gdansk, Elblag and Pia (northern part of Poland) have been investigated with regard to their silver content. In total, 527 samples including 25 mushroom species of six families (Agaricaceae, Boletaceae, Cantharellaceae, Hygrophoraceae, Coprinaceae andRussulaceae) were examined. Among the fungi examined onlyAgaricus campestris andA. augustus were heavy bioaccumulating species and showed the highest concentrations of 35 mg Ag/kg dry weight (1.1–150) and 2.0–6.9 mg/kg, respectively. Silver concentrations exceeding 1.0 mg/kg dry weight were noted inBoletus aestivalis, Lepista nuda, L. personata, and in some specimens ofB. edulis, Leccinum scrabum, L. vulpinum, Cantharellus cibarius andCoprinus comatus.

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Silbergehalt in wildwachsenden Pilzen Nordpolens

Zusammenfassung Der Silbergehalt in wildwachsenden und vorwiegend eßbaren, auf dem Gebiet der Woiwodschaften Gdask, Elblag und Pia (Nordpolen) in den Jahren 1889–1992 gesammelten Pilzsorten wurde untersucht. Im ganzen wurden 527 Proben von 25 Arten der 6 Familien (Agaricaceae, Boletaceae, Cantharellaceae, Hygrophoraceae, Coprinaceae, Russuulaceae) zugehörenden Pilzen untersucht. Von diesen Pilzen waren nurAgaricus campestris undA. augustus stark bioanreichernde Arten mit höchsten Konzentrationen von 35 mg Ag/kg Trockenmasse (1.5–150) und 2.0–6.9 mg/kg. Eine Silberkonzentration von über 1.0 mg/kg Trockenmasse wurde inBoletus aestivalis, Lepista nuda, L. personata und in einigen Exemplaren vonB. edulis, Leccinum scrabum, L. vulpinum, Cantharellus cibarius undCoprinus comatus feststellt.

     

Analysis of Mechanical Properties of Laminated Seams

ABSTRACT

The main goal of this article is to analyze the seam quality by influence of lamination process parameters on the strength properties of laminated seams in cotton clothing products. The seam quality index is defined by maximal force to seam rupture and relative elongation during rupture. These parameters are obtained during the delamination test and shear test. The obtained statistical equations allow to describe, predict, and optimize the seam quality versus the product requirements and seam location within the product. The obtained results suggest that the strength properties of laminated seams can be determined by means of both mentioned tests.     

Germination as a process to improve the antioxidant capacity of Lupinus angustifolius L. var. Zapaton

Antioxidant capacity, measured by glutathione (GSH), superoxide dismutase-like activity (SOD-like activity), peroxyl radical-trapping capacity (PRTC), trolox equivalent antioxidant capacity (TEAC) and inhibition of lipid peroxidation in unilamellar liposomes of egg yolk phosphatidylcholine (PC) has been evaluated in raw and germinated lupin seeds (Lupinus angustifolius L. var. Zapaton) for 2, 3, 4, 5, 6 and 9 days. The content of antioxidant vitamins E and C has been also studied. The tripeptide GSH kept invariable for the first 5 days of germination and suffered a decrease of 20 and 78% after 6 and 9 days, respectively. During lupin germination, SOD-like activity increased slightly whilst PRTC doubled the amount after 9 days. TEAC values changed slightly up to 5 days of germination but after 6 and 9 days a significant increase (25 and 28%, respectively) was found. The oxidation of PC was inhibited by germinated lupin extracts and 9-day germination seeds provided the highest inhibition. Furthermore, germinated lupins provided more vitamin C, vitamin E activity and polyphenols than raw seeds, and the largest amounts of these bioactive compounds were found after 6 days of germination. Therefore, germination of lupin seeds (Lupinus angustifolius L. var. Zapaton) seems to be a good process to enhance their antioxidant capacity.     

Effect of calcium ions on the solubility of muscular collagen and tenderness of beef meat

The aim of the present study was to determine the effect of aqueous solutions of calcium chloride and calcium lactate on the solubility of beef collagen in raw and cooked meat. The content of total collagen, water- and acetic acid-soluble collagen and insoluble collagen was determined in beef samples. Shearing force was measured after heat treatment. It was found that calcium ions had no significant effect on the solubility of muscular collagen. An improvement in beef tenderness (27%-34%) caused by calcium ions did not result from breaking of the native structure of muscular collagen.     

Influence of a photoinitiator on the photochemical stability of poly(methyl methacrylate) studied with fourier transform infrared spectroscopy

Fourier transform infrared (FTIR) spectroscopy was used to investigate the effect of a commercial photoinitiator [2,2‐dimethoxy‐2‐phenylacetophenone (DMPA); Irgacure 651, Ciba, Basel, Switzerland] incorporated into poly(methyl methacrylate) (PMMA). Pure PMMA and modified PMMA (containing 5% DMPA) films were exposed to a xenon lamp in air. Qualitative and quantitative analyses of the recorded FTIR absorption spectra were done. This allowed us to determine the differences in the course of polymer photooxidative degradation occurring in PMMA and PMMA doped with DMPA. We found that the initiator added to polymer film enhanced the efficiency of the formation of the photooxidized products containing functional groups of different types, which could be distinguished by mathematical treatment of the FTIR spectra. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Relation of crystalline structure and mechanical properties of nucleated polypropylene

Four heterogeneous nucleating agents were added to polypropylene (PP) homoblock and random copolymers. Melting and crystallization of the polymers were studied by differential scanning calorimetry (DSC), and characteristics derived from the crystallization exotherms were related to the mechanical properties of injection molded bars. A very close correlation was found between the crystallization characteristics and Young's modulus of the polymers. The general correlation proved to be valid for all three polymers studied and also for each nucleating agent. The developed empirical correlation makes possible the approximate prediction of stiffness from a simple DSC trace. Further study is needed to give the relationship better physical meaning and to extend it to other mechanical properties.     

Effect of nanosilver on the photodegradation of poly(lactic acid)

The poly(lactic acid), PLA, mixed with nanosilver in solution easily forms nanocomposite in solid state (after solvent evaporation), which was proved by UV–Vis spectroscopy. This work focuses on photodegradation occurring in PLA films doped with nanosilver. The changes in chemical structure of photodegraded PLA has been determined using FTIR spectroscopy. Differential scanning calorimetry of UV‐irradiated PLA samples provided information on polymer glass transition and crystallization/melting processes. It was found that PLA alone is more sensitive to photodegradation than PLA/silver nanocomposites. The mechanism of nanocomposite photodegradation and effect of nanosilver was discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40144.     

Ultrasmall Co3O4 Nanocrystals Strongly Enhance Solar Water Splitting on Mesoporous Hematite

The synthesis of crystalline, nonagglomerated, and perfectly dispersible Co₃O₄ nanoparticles with an average size of 3–7 nm using a solvothermal reaction in tert‐butanol is reported. The very small size and high dispersibility of the Co₃O₄ nanoparticles allow for their homogeneous deposition on mesoporous hematite layers serving as the photoactive absorber in the light‐driven water splitting reaction. This surface treatment leads to a striking photocurrent increase. While the enhancement of hematite photoanode performance by cobalt oxides is known, the preformation and subsequent application of well‐defined cobalt oxide nanoparticles are novel and allow for the treatment of arbitrarily complex hematite morphologies. Photoelectrochemical and transient absorption spectroscopy studies show that this enhanced performance is due to the suppression of surface electron–hole recombination on time scales of milliseconds to seconds.     

The effect of germination process on the superoxide dismutase-like activity and thiamine,riboflavin and mineral contents of rapeseeds

Seeds of double low oilseed rape variety Mango (Brassica napus, var. oleifera) were subjected to a 7-day germination at 25 °C and 95% moisture content in darkness in a conditioning cabinet. The effects of the germination process on the superoxide dismutase-like activity (SOD-like activity), thiamine (vitamin B₁) and riboflavin (vitamin B₂) and minerals, such as Ca, Mg, Cu, Fe and Mn, were studied. Correlations between individual mineral contents, vitamin B₁ and B₂ contents, and the ability of phosphate buffered saline (PBS) extracts from germinated rapeseed to scavenge superoxide anion radicals in vitro were also investigated. SOD-like activity showed a gradual increase after the second day of germination, reaching a maximum level on the sixth day, and remained almost constant up to the end of the germination period. During germination, thiamine underwent a progressive decrease up to the sixth day, reaching a constant level between the sixth and the seventh day. In contrast, riboflavin content increased throughout the germination period up to the fifth day, and after that a constant level was observed. Levels of Ca and Mg were almost constant up to the fourth day and after that an increase of these minerals was observed. Cu and Mn increased during the germination process, and retentions of 33% and 22%, respectively, were observed at the end of germination. Fe content dropped after 1 day of germination and from there onward it started to increase gradually and an 18% retention was observed in 7-day germinated seeds. Positive correlations between SOD-like activity and riboflavin (r = 0.87), Cu (r = 0.74) and Mn (r = 0.87) were found during rapeseed germination.