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Synthesis and Characterization of Co-Mo Bimetallic Carbides
No full textCo-Mo carbides were prepared by impregnation with aqueous solution of metal salts and sucrose into ordered mesoporous SBA-15 silica template using carbothermal hydrogen reduction. Bimetallic Co-Mo carbide obtained by using carbothermal hydrogen reduction of Co-Mo precursors is formed when the Co-Mo molar ratio is 1.0. The obtained samples were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. Electrochemical characterization of obtained materials were performed by cyclic voltammetry in acid solution
Novel Approach for Determination of Potentially Toxic Elements via ICP-OES in Aqueous Solutions of Building Materials with Industrial Byproduct Addition
No full textNew global tendencies for waste materials reusing in building materials are imposing the request for improved performances of chemical analysis methods and the improvements of matrices used. A new method for optical emission spectrometry with inductively coupled plasma (ICP-OES) is developed and validated for the chemical analysis (35 elements: Al, Be, Cd, So, Cr, Cu, Fe, Mn, Mo, Ni, V, Mo, Zn, Pb , Bi, Si, Zr, W, As, Se, Sb, Sn, Ti, Ba, B, Ag, Mg, Ca, K, Na, S, P, Ga, In, Li) in leachate of fly ash. Validation performances and the uncertainty of measurement were resolved. Uncertainty of measurements were resolved by three routes: validation procedure, participation in proficiency testing (PT) schemes and standard method. The obtained method is a new simple and effective analyzing route for determination of undesired trace elements and their quantity comprised in leachates of fly ash, and leachates of building materials with addition of fly ash (cement binders and mortars). In order to prove its accuracy and precision, the developed method was employed on laboratory samples of cement binders and mortars. Results were compared with limit values provided in the standard. Multivariate analyses, i.e. cluster analysis and principal component analysis, were applied to establish interrelations between analyzed samples, and to certify the developed ICP-OES method
The Effects of Meldonium on the Renal Acute Ischemia/Reperfusion Injury in Rats
No full textAcute renal ischemia/reperfusion (I/R) injury is a clinical condition that is challenging to treat. Meldonium is an anti-ischemic agent that shifts energy production from fatty acid oxidation to less oxygen-consuming glycolysis. Thus, in this study we investigated the effects of a four-week meldonium pre-treatment (300 mg/kg b.m./day) on acute renal I/R in male rats (Wistar strain). Our results showed that meldonium decreased animal body mass gain, food and water intake, and carnitine, glucose, and lactic acid kidney content. In kidneys of animals subjected to I/R, meldonium increased phosphorylation of mitogen-activated protein kinase p38 and protein kinase B, and increased the expression of nuclear factor erythroid 2-related factor 2 and haeme oxygenase 1, causing manganese superoxide dismutase expression and activity to increase, as well as lipid peroxidation, cooper-zinc superoxide dismutase, glutathione peroxidase, and glutathione reductase activities to decrease. By decreasing the kidney Bax/Bcl2 expression ratio and kidney and serum high mobility group box 1 protein content, meldonium reduced apoptotic and necrotic events in I/R, as confirmed by kidney histology. Meldonium increased adrenal noradrenaline content and serum, adrenal, hepatic, and renal ascorbic/dehydroascorbic acid ratio, which caused complex changes in renal lipidomics. Taken together, our results have confirmed that meldonium pre-treatment protects against I/R-induced oxidative stress and apoptosis/necrosis
A contribution to the estimation of berry fruits quality
No full textThis study aimed to estimate the quality (in terms of standard chemical parameters, total antioxidative activity /AO/ and thermal properties) of the fresh strawberry (Fragaria xananassa L. Duch.), raspberry (Rubus idaeus L.) and blackberry (Rubus fruticosusL.) samples grown in the Western Serbia. The examined blackberry variety was found to exhibit the most potent AO (DPPH /2,2-diphenyl-1-picrylhydrazyl/ assay, EC50 4.05 +/- 0.22 mu g and ARP 0.25 +/- 0.03 mu g(-1); Hydroxo-Perhydroxyl Mercury(II) Complex /HPMC/ assay, 0.072 +/- 0.007%/mu L), due to the enriched contents of both total phenolics and anthocyanins. It was actually followed by the raspberry and strawberry samples. Unlike the aforementioned trend for AO, thermal behaviour of all samples was similar. This is first time ever that a DC polarographic HPMC assay has been applied for the characterisation of the fresh berry fruits. Further studies aiming to screen total AO of the soft fruit during growth, storage and processing might be well facilitated by the application of this low cost, rapid, easy-to-handle and reliable electrochemical assay
Essential oils of coriander and sage: Investigation of chemical profile, thermal properties and QSRR analysis
No full textEssential oils (EOs) are aromatic oily liquids prepared from plant material. Many plants are rich in EOs, which usually consisted of different secondary metabolites such as terpenoids. The EOs or their components have been shown to exhibit antioxidant, antimicrobial, antiviral, antimycotic, antitoxigenic, antiparasitic and insecticidal properties, which is main reason for their ivenstigation. Coriander and sage essential oils, isolated by hydrodistillation, were analyzed using gas chromatography, differential scanning calorimetry and thermogravimetry techniques in order to correlate chemical composition and thermal behavior. Results showed that evaporation process of sage EO takes place in two steps, while coriander EO was evaporated in one step. The activation energy of the evaporation process of both EOs was in accordance to the evaporation enthalpy of dominant compounds in analyzed samples. The quantitative structure-retention relationship (QSRR) was employed to predict the retention time (RT) of essential oil compounds obtained by GC analysis, using five molecular descriptors selected by genetic algorithm. The selected descriptors were used as inputs of an artificial neural network (ANN), to build an RT predictive QSRR model. The coefficient of determination was 0.969, indicating that this model could be used for prediction of RT values for coriander and sage essential oil compounds
Nonlinear optical spectroscopy and two-photon excited fluorescence spectroscopy reveal the excited states of fluorophores embedded in a beetle's elytra
No full textUpon illumination by ultraviolet light, many animal species emit light through fluorescence processes arising from fluorophores embedded within their biological tissues. Fluorescence studies in living organisms are however relatively scarce and so far limited to the linear regime. Multiphoton excitation fluorescence analyses as well as nonlinear optical techniques offer unique possibilities to investigate the effects of the local environment on the excited states of fluorophores. Herein, these techniques are applied for the first time to study of the naturally controlled fluorescence in insects. The case of the male Hoplia coerulea beetle is investigated because the scales covering the beetle's elytra are known to possess an internal photonic structure with embedded fluorophores, which controls both the beetle's coloration and the fluorescence emission. An intense two-photon excitation fluorescence signal is observed, the intensity of which changes upon contact with water. A third-harmonic generation signal is also detected, the intensity of which depends on the light polarization state. The analysis of these nonlinear optical and fluorescent responses unveils the multi-excited states character of the fluorophore molecules embedded in the beetle's elytra. The role of form anisotropy in the photonic structure, which causes additional tailoring of the beetle's optical responses, is demonstrated by circularly polarized light and nonlinear optical measurements
The effects of osmotic dehydration of white cabbage on polyphenols and mineral content
No full textWithin this work, the content of polyphenolic compounds, vitamin C and minerals in white cabbage (Brassica oleracea) was studied, as affected by the variety of cabbage (var. Futoski, hybrid Bravo) and osmotic dehydration in different osmotic solutions. Three osmotic solutions were used: 1) aqueous solution of NaCl and sucrose (S1); 2) mixture of S1 and sugar beet molasses in proportion 1:1 (S2); and 3) 100% beet molasses (S3). The osmotic dehydration of cabbage in molasses (S3) resulted in a substantial increase in the content of iron and potassium in the dehydrated cabbage by 80-100%. On the other hand, a loss of minerals (Fe, Mg and Ca) at 30-60% after cabbage dehydration in sucrose solution is presented. Also polyphenols content was significantly increased during osmotic dehydration in molasses particularly for kaempherol (6.63 mg/kg dm), p-cumaric acid (1.01 mg/kg dm), caffeic acid (20.35 mg/kg dm), catechin (153.81 mg/kg dm) and gallic acid (17.54 mg/kg dm). Additionally, osmotic dehydration process demonstrated a good retention of L-ascorbic acid in cabbage
CaO&CaSO4 and CaO&Al-2(SO4)(3) as Pectin Precipitants-Model of Overlapping Diffuse Layers
No full textThis work is concerned with the theoretical basis of novel sugar beet juice purification method using binary systems CaO&CaSO4 and CaO&Al-2(SO4)(3). The Gouy-Chapman-Stern (GCS) model of overlapping of diffuse layers of EDLs on pectin surface and that on Ca2+ and Al(3+ )ions, theoretically explains this method. The change of the zeta potential was used to quantitatively indicate overlapping of diffuse layers. For the experiment two model solutions of pectin (0.1 % w/w) were prepared, while the concentrations of CaO&CaSO4 and CaO&Al-2(SO4)(3) in the range of 50-500 g dm(-3) were used. The greater decrease in the absolute value of zeta potential indicated greater overlapping of diffuse layers between pectin particles and Ca2+ and Al3+ ions and faster coagulation of pectin. The overlapping degree increased with increased concentration of these binary systems. Pectin with a greater surface charge and multivalent Al(3+ )from CaO&Al-2(SO4), exerted a greater impact on the zeta potential. Optimal quantities of the applied binary mixtures were as follows: 256-640 mg g(-1) pectin. This is much lower than CaO commonly used in the conventional process of sugar beet juice purification (about 9 g g(-1) pectin)
Possibility for Removing Products of Thermal Degradation of Edible Oil by Natural Aluminosilicates
No full textEveryday food preparation often involves cooking on vegetable oil, where heating at temperatures over 110 degrees C changes the quality of oil due to various chemical reactions. In this paper, the degree of thermal degradation of edible oil was investigated when heating oil at a temperature ranging from 110 to 190 degrees C for 10 and 30 min. The reference to the quality of edible oil is the content of free fatty acids (FFA) which increases as the temperature rises, due to hydrolysis. By removing the thermal degradation products of the edible oil used, it would be possible to prolong the time of use of the oil for other useful purposes, and thus its final disposal as waste, would be postponed, which is in accordance with environmental protection requirements. In line with this, the possibility of adsorption of FFA on natural aluminosilicates was investigated. The results obtained show a decrease in FFA content of 72 to 80%, depending on the time of heating and the type of adsorbent used. Further research should be continued on the regeneration of used edible oil by testing other quality parameters, as well as the application of other adsorbent
Microprocessing of a steel surface by single pulses of variable width
No full textSingle-pulse microprocessing of a steel surface with a variable pulse width (0.3-12.3 ps) and a wavelength of 515 nm was performed. The morphology of the craters was visualized by a scanning electron microscope and an optical profilometer. The nonmonotonic behavior of ablation thresholds with a minimum at approximate to 1.5 ps, due to achieving the electron-phonon relaxation time of the absorbed energy in the steel was revealed. It is shown that, with an increase in the pulse width in the considered width range, the efficiency of the ablation decreases by a factor of 2, which is explained by the partial transition from the phase explosion to the surface evaporation