slow release rubber formulations containing ZnSO4

Styrene butadiene (SBR) and natural rubber (NR) can be used as binding matrices to control the release of zinc (Zn) which is a micro-nutrient for plants. The leaching rate of zinc in an aqueous medium depends on the concentration of zinc sulphate loaded in the two types of rubber used, the temperature of the surrounding environment and the pH of the aqueous medium. Water uptake was increased with increasing concentration of ZnSO₄. The sustained release of zinc ions from the investigated formulations was prolonged for over five months. The mechanical properties of the vulcanizates were affected as the concentration of zinc sulphate changed.     

Density functional theory study of hydrogen storage on Ni-doped C59X (X = B,N) heterofullerene

ABSTRACT

Hydrogen storage reactions on Ni ? C₅₉X(X = B, N) heterofullerene are investigated by using the state-of-the-art density functional theory calculations. The Ni atom prefers to bind at the bridge site between two hexagonal rings, and can bind up to five hydrogen molecules with average adsorption energies of (?0.94, ?0.48, ?0.33, ?0.25 and ?0.20 eV) per hydrogen molecule for Ni ? C₅₉B, while (?1.20, ?0.60, ?0.41, ?0.28 and ?0.23 eV) per hydrogen molecule for Ni ? C₅₉N. With no metal clustering, the system gravimetric capacities are expected to be as large as 10.87 and 10.85 wt % for 5H₂NiC₅₉B?and 5H₂NiC₅₉N, respectively. While the desorption activation barriers of the complexes 1H₂ + C₅₉X?(X = B, N)?are outside the Department of Energy domain (?0.2 to ?0.6 eV), the desorption activation barriers of the complexes nH₂ + C₅₉X(X = B, N)(n = 2 ? 5) are inside this domain. The hydrogen storage of the irreversible 1H₂ + NiC₅₉X?(X = B, N) and reversible 2H₂ + NiC₅₉X?(X = B, N) interactions is characterised in terms of density of states and projected densities of states, pairwise and non-pairwise additivity, infrared, Raman, electrophilicity and molecular electrostatic potentials.     

Determination of Chemical Compounds and Investigation of Biological Properties of Matricaria chamomilla Essential Oils,Honey, and Their Mixture

This exploratory investigation aimed to determine the chemical composition and evaluate some biological properties, such as antioxidant, anti-inflammatory, antidiabetic, and antimicrobial activities, of Matricaria chamomilla L. essential oils (EOs). EOs of M. chamomilla were obtained by hydrodistillation and phytochemical screening was performed by gas chromatography–mass spectrophotometry (GC-MS). The antimicrobial activities were tested against different pathogenic strains of microorganisms by using disc diffusion assay, the minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods. The antidiabetic activity was performed in vitro using the enzyme inhibition test. The antioxidant activity of EOs was tested using the free radical scavenging ability (DPPH method), ferrous ion chelating (FIC) ability, and β-carotene bleaching assay. The anti-inflammatory effects were tested in vivo using the carrageenan-induced paw edema method and in vitro using the inhibition of the lipoxygenase test. The analysis of the phytochemical composition by GC-MS revealed that camphor (16.42%) was the major compound of EOs, followed by 3-carene (9.95%), β-myrcene (8.01%), and chamazulene (6.54%). MCEO, honey, and their mixture exhibited antioxidant activity against the DPPH assay (IC₅₀ ranging from 533.89 ± 15.05 µg/mL to 1945.38 ± 12.71 µg/mL). The mixture exhibited the best radical scavenging activity, with an IC₅₀ of 533.89 ± 15.05 µg/mL. As antidiabetic effect, EO presented the best values against α-glucosidase (265.57 ± 0.03 μg/mL) and α-amylase (121.44 ± 0.05 μg/mL). The EOs and honey mixture at a dose of 100 mg/kg exhibited a high anti-inflammatory effect, with 63.75% edema inhibition after 3 h. The impact of EOs on the studied species showed an excellent antimicrobial (Staphylococcus aureus ATCC 29213 (22.97 ± 0.16 mm)), antifungal (Aspergillus niger (18.13 ± 0.18 mm)) and anti-yeast (Candida albicans (21.07 ± 0.24 mm) effect against all the tested strains. The results obtained indicate that the EOs of M. chamomilla could be a potential drug target against diabetes, inflammation and microbial infections; however, further investigations to assess their bioactive molecules individually and in combination are greatly required.     

THE CHEMICAL COMPOSITIONS OF MINERALS IN QINGZHEN METEORITE AND ITS GEOCHEMISTRY SIGNIFICANCE

The chemical compositions of silicate minerals, sulphide minerals and metal Fe-Ni in theQingzhen meteorite were measured by the microprobe analyses. Based upon these chemicalcompositions, the cosmochemical behaviour and characteristics of the existing forms of themajor elements in the Qinzhen meteorite have been discussed. These characteristics show thatunder the S-rich, O-poor, and strongly reducing conditions, the light metal elements, such asCa, Mg, K, Na may form sulphide, and metal Fe-Ni may contain Si and P. However, we con-sider that the light metal-sulphide can be stable in the lower mantle and there are some Siand P in the Fe-Ni core. Finally, an earth core-mantle model is established, where the Fe-Ni core contains some Si and P; the lower mantle is composed of Mg-rich silicate, SiO_2 andsulphide; the upper mantle, of silicate and oxide.     

The Imaginary Point Spectrum and Hypercyclicity

Let A be a generator of a C₀-semigroup T(·) on a separable Banach space. Under suitable conditions on the imaginary point spectrum of A, we show that T(·) is hypercyclic.     

DC electrical resistivity for CoxNi5/3−xSb1/3Fe1O4 ferrites

The DC electrical resistivity (p) was studied for Co substituted SbNi ferrites as a function of temperature and composition. The experimental results showed that DC resistivity, Curie temperature and activation energies for electrical conduction increase as Co-ion substitution decreases. The DC electrical conductivity increases as temperature increases. The real part of dielectric constant (e') was found to be inversely proportional to the root mean square value of the electrical resistivity.     

Effect of Microalgae Polysaccharides on Biochemical and Metabolomics Pathways Related to Plant Defense in Solanum lycopersicum

Applied Biochemistry and Biotechnology - Microalgae are photosynthetic microorganisms that produce several bioactive molecules that have received considerable attention in scientific and industrial...     

Transport of Carbamazepine,Ciprofloxacin and Sulfamethoxazole in Activated Carbon: Solubility and Relationships between Structure and Diffusional Parameters

The transport of carbamazepine, ciprofloxacin and sulfamethoxazole in the different pores of activated carbon in an aqueous solution is a dynamic process that is entirely dependent on the intrinsic parameters of these molecules and of the adsorbent. The macroscopic processes that take place are analyzed by interfacial diffusion and reaction models. Modeling of the experimental kinetic curves obtained following batch treatment of each solute at 2 µg/L in tap water showed (i) that the transport and sorption rates were controlled by external diffusion and intraparticle diffusion and (ii) that the effective diffusion coefficient for each solute, with the surface and pore diffusion coefficients, were linked by a linear relationship. A statistical analysis of the experimental data established correlations between the diffusional parameters and some geometrical parameters of these three molecules. Given the major discontinuities observed in the adsorption kinetics, the modeling of the experimental data required the use of traditional kinetic models, as well as a new kinetic model composed of the pseudo first or second order model and a sigmoidal expression. The predictions of this model were excellent. The solubility of each molecule below 60 °C was formulated by an empirical expression.     

Pulsed KrF excimer laser induced degradation of cellulose based insulating paper

We report on the accelerated ageing of cellulose based insulating paper by means of pulsed UV laser irradiation (λ = 248 nm) under various experimental conditions including paper composition, background gas (He, N₂ and air) and moisture content of the paper. The temperature reached by the paper samples during their laser irradiation was monitored by means of real-time IR imaging. It is shown that the equilibrium temperature (T _eq) reached by the paper increases from ~30 to ~270 °C when the laser energy density was raised from 15 to 550 mJ cm⁻². The laser irradiated samples were systematically characterized by means of scanning electron microscopy (SEM) observations and degree of polymerization (DP_v) measurements. Interestingly, it is found that, for a given moisture content, the degradation level of the cellulose is mainly triggered by the T _eq value reached during the laser irradiation. Moreover, their moisture content was found to influence significantly the number of laser produced bond scissions (it doubles when the moisture content is increased from 0.5 to 6%); the paper degradation is apparently not affected by the presence of oxygen as the background gas. These results suggest that the laser induced cellulose degradation occurs through a direct photolysis (i.e. direct breakage of C–C, C–O and C–H bonds), leading to radicals formation, which, in turn, are believed to induce the acid hydrolysis degradation mechanism, the latter being moisture dependent. The activation energy (E _a) of each gaseous species collected after the laser degradation was estimated. Their E _a values were found to be in good agreement with the one associated to the laser depolymerisation of cellulose (i.e. ~56 kJ mol⁻¹), suggesting thereby a direct correlation between the cellulose degradation and the formation of the detected gaseous species. Finally, the pulsed laser irradiation can be seen as an attractive tool to identify primarily generated molecules, on a very short time scale, that can be used as relevant chemical markers for the monitoring of the ageing of transformers materials with cellulose.