Antioxidant effects of Rosemary extract on the accelerated degradation of ethylene-propylene-diene monomer

Abstract The goal of this paper is the qualification of natural antioxidants (rosemary extract, capsaicin, quercetin or oleanolic acid) playing as antioxidant. The stabilization activities were investigated in several formulations based on ethylene-propylene-diene-terpolymer (EPDM) in pristine state or after -irradiation, when the accelerated degradation scission of polymer macromolecules followed by the mitigation of oxidation. Three evaluation procedures: chemiluminescence, FTIR spectroscopy and thermal analysis were applied for the characterization of the stability contribution. The durability of studied EPDM formulations is discussed for the assessment of material life. The improved behavior of structured hybrids useful for the optimization application regimes is essentially based on the antioxidant properties of polyphenolic components in the cases of natural antioxidant

Kinetics of the Non-isothermal Degradation of POSS/EPDM Hybrids Composites

Polyhedral Oligomeric Silsesquioxane (POSS)/Ethylene-propylene-diene monomer (EPDM) composite, at 3% wt of POSS, is prepared by the evaporation of solvent (CHCl3) from polymer/filler system at room temperature and is investigated, by the means of thermogravimetric analysis (TGA), and the obtained TGA data are treated by the Kissinger method to get the apparent activation energy (Ea) of degradation. The results obtained for the composites, at different levels of irradiation, are discussed and compared with each other and with those obtained for pristine EPDM. A good improvement of the thermal stability, with respect to the neat polymer, is found showing the effect of the POSS molecules on the degradation rate. A classification among the samples at different levels of radiations is also drawn up, showing also in this case, the beneficial effect of the POSSs presence

A problem of Erd\H{o}s-Graham-Granville-Selfridge on integral points on hyperelliptic curves

Erd\H{o}s, Graham, and Selfridge considered, for each positive integer $n$, the least value of $t_n$ so that the integers $n+1, n+2, \dots, n+t_n$ contain a subset the product of whose members with $n$ is a square. An open problem posed by Granville concerns the size of $t_n$, under the assumption of the ABC Conjecture. We establish some results on the distribution of $t_n$, and in the process solve Granville's problem unconditionally.Comment: 25 pages. Comments welcom

Power savings for counting solutions to polynomial-factorial equations

Let $P$ be a polynomial with integer coefficients and degree at least two. We prove an upper bound on the number of integer solutions $n\leq N$ to $n! = P(x)$ which yields a power saving over the trivial bound. In particular, this applies to a century-old problem of Brocard and Ramanujan. The previous best result was that the number of solutions is $o(N)$. The proof uses techniques of Diophantine and Pad\'e approximation.Comment: 26 page

Tin dioxide sol-gel derived thin films deposited on porous silicon

Undoped and Sb-doped SnO2 sol¿gel derived thin films have been prepared for the first time from tin (IV) ethoxide precursor and SbCl3 in order to be utilised for gas sensing applications where porous silicon is used as a substrate. Transparent, crack-free and adherent layers were obtained on different types of substrates (Si, SiO2/Si). The evolution of the Sn¿O chemical bonds in the SnO2 during film consolidation treatments was monitored by infrared spectroscopy. By energy dispersive X-ray spectroscopy performed on the cross section of the porosified silicon coupled with transmission electron microscopy, the penetration of the SnO2 sol¿gel derived films in the nanometric pores of the porous silicon has been experimentally proved

Ecosystem-bedrock interaction changes nutrient compartmentalization during early oxidative weathering

Ecosystem-bedrock interactions power the biogeochemical cycles of Earth's shallow crust, supporting life, stimulating substrate transformation, and spurring evolutionary innovation. While oxidative processes have dominated half of terrestrial history, the relative contribution of the biosphere and its chemical fingerprints on Earth's developing regolith are still poorly constrained. Here, we report results from a two-year incipient weathering experiment. We found that the mass release and compartmentalization of major elements during weathering of granite, rhyolite, schist and basalt was rock-specific and regulated by ecosystem components. A tight interplay between physiological needs of different biota, mineral dissolution rates, and substrate nutrient availability resulted in intricate elemental distribution patterns. Biota accelerated CO2 mineralization over abiotic controls as ecosystem complexity increased, and significantly modified stoichiometry of mobilized elements. Microbial and fungal components inhibited element leaching (23.4% and 7%), while plants increased leaching and biomass retention by 63.4%. All biota left comparable biosignatures in the dissolved weathering products. Nevertheless, the magnitude and allocation of weathered fractions under abiotic and biotic treatments provide quantitative evidence for the role of major biosphere components in the evolution of upper continental crust, presenting critical information for large-scale biogeochemical models and for the search for stable in situ biosignatures beyond Earth.Comment: 41 pages (MS, SI and Data), 16 figures (MS and SI), 6 tables (SI and Data). Journal article manuscrip