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Operating parameter optimization of cell surface hydrophobicity test for ureolytic bacteria
No full textAs one of the main non-covalent relations in microbiological-based systems, cell surface hydrophobicity (CSH) can be observed as a relevant parameter for biodegradation capability and suggested bacterial behaviour and biofilm formation during a bioremediation process. On the other hand, the role of ureolytic bacteria in bioremediation has subsequently led to the examination of this bacterial type in different engineering fields. In order to optimize the operating parameters of microbial adhesion to hydrocarbons test (MATH) for ureolytic bacteria, Box-Behnken experimental design was conducted for five ureolytic bacteria isolated from soils, as well as for the reference strain Sporosarcina pasteurii DSM 33. The optimization was completed with and without the essential substrate for the targeted metabolic reaction, with the aim to compare differences in bacterial hydrophobicity. A vortex time of 2 min, a hydrocarbon volume of 0.5 mL, and a phase separation time of 15 min are recommended as MATH operating parameters for all tested ureolytic bacteria. Although all bacteria are hydrophobic, lower CSH values in the presence of urea were observed for the same bacterium, which could be explained by the interaction of urea with the organic phase of the separation system, as well as a rapid ureolysis process that also occurs during the application of ureolytic bacteria in biotechnology systems
The effects of solution type temperature and time on antioxidant capacity of osmotically dried celery leaves
No full textOsmotic drying of celery leaves was studied in two osmotic solutions (ternary aqueous solution and sugar beet molasses), at three temperatures (20, 35, and 50 degrees C), and diverse immersion periods (1, 3, and 5 hours). The aim was to examine the influence of the used hypertonic agent, temperature and immersion time on antioxidant capacity (AOC) and color characteristics of the samples. The AOC of celery leaves was assessed by the spectrophotometric assays (ABTS, FRAP, and DPPH), as well as two direct current polarographic assays, hydroxo perhydroxo mercury (II) complex assay based on the decrease of anodic current of hydroxo perhydroxo mercury (II) complex and mercury reduction antioxidant power assay based on the decrease of a cathodic current of Hg (II) reduction. Total phenolic content was determined by Folin-Ciocalteu assay. The relative antioxidant capacity index, calculated by assigning equal weight to all applied assays was used to achieve a more comprehensive comparison between analyzed samples, as well as applied assays. The obtained results indicated decreases in the AOC of celery leaves during the osmotic treatment in ternary solution, while the AOC was increased in sugar beet molasses solution. According to relative antioxidant capacity index evaluation the most convenient process parameters were temperature of 35 degrees C and immersion time of 5 hours
Kinetics of the exchange of water absorbed in silica hydrogel with ethanol: Modelling by Brouers and Sotolongo-Costa fractal kinetics
No full textIsothermal kinetics of the exchange of absorbed water in a silica hydrogel (SH) with ethanol was examined. The isothermal kinetic curves of absorbed water exchange with ethanol were measured at the temperatures: T = = 297, 306 and 316 K. The rate of the exchange was analysed as a function of time. The possibility of mathematical description of the kinetics of exchange by the Brouers and Sotolongo-Costa's (BS) fractal's kinetics model was examined. Parameter values (n, tau, beta) of the model and their changes with temperature were calculated. By applying the method of Ozao, it was determined that the rate limiting step of the process of exchange was the rate of exchange of the absorbed water with ethanol. Values of the fractal dimension of the SH-ethanol interphase were calculated. The dependences of the effective time-dependent rate coefficient, activation energy and pre-exponential factor on time and degree of exchange were calculated and discussed. The proposed model of the mechanism of the exchange of absorbed water with ethanol was discussed
Antioxidant and enzyme-inhibitory activity of peppermint extracts and essential oils obtained by conventional and emerging extraction techniques
No full textPeppermint is widely used medicinal plant with distinguished bioactive potential, therefore, the aim of present work was to develop novel peppermint extracts with high activity by application of traditional and emerging separation techniques. Conventional hydrodistillation and microwave-assisted hydrodistillation (MWHD) were applied for recovery of essential oil (EO), while organic solvent extraction using Soxhlet apparatus, microwave-assisted and ultrasound-assisted process and supercritical fluid extraction (SFE) were applied for non-selective recovery of peppermint lipophilic extracts. Extracts were characterized in terms of terpenoids profile with special emphasis on content of major compounds (mentol, menthone, isomenthol and eucalyptol). Antioxidant activity (DPPH, ABTS, CUPRAC, FRAP, chelating and phosphomolybdenum assay) and enzyme-inhibitory assays (acetylcholinesterase, butyrylcholinesterase, tyrosinase, amylase and glucosidase inhibition) were used for screening of peppermint bioactivity. MWHD was recognized as alternative for traditional process in EO recovery, while SFE extracts were useful for green production of solvent-free peppermint extracts rich in terpenoids and other lipophilic bioactives
Low sugar jellies of berry fruits: the impact of low vs. high temperature regime on their chemical composition and antioxidativity
No full textThis study focuses on the impact of low and high temperature regimes on the chemical composition and antioxidativity of low sugar berry fruits jellies. High quality fruits (strawberry, raspberry and blackberry) were collected from Western Serbia region, quite well recognised both nationally and internationally due to an extremely well developed practice in growing berry fruits. The obtained results have clearly indicated the importance of low temperature regime for enriched contents of both total phenolics and anthocyanins followed by an enhanced antioxidativity. Rubus fruticosus L. Cacak Thornless cultivar, the only autochthonous berry fruit variety screened herein, may be firmly recommended as a raw material for industrial production of low sugar blackberry jellies with exceptional characteristics. This innovative procedure of preparing berry fruit jellies have encompassed the application of low temperature regime (55 degrees C), lower content of sugar (40%), seeds separation from jellies followed by no use of pectin throughout the whole process. [GRAPHICS]
Synthesis and characterization of new cerium doped phosphate tungsten bronze
No full textCerium doped phosphate tungsten bronze (Ce-PWB) was synthetized by phase transformations of CePW12O40x6H2O (Ce-6-PWA) salt. The solid-solid transformations of Keggin's anion of this salt, including dehydration processes and bronze's formation are finished at about 600 oC. The constructions of Ce-6-PWA and Ce-PWB were characterized by thermal analysis (TGA and DTA), X-ray powder diffraction (XRPD), and Fourier-transform infrared spectra (FTIR)
Mathematical model, numerical simulation and optimization of rotating valve feeder in animal feed production
No full textThe processes of transportation of bulk materials from silos and hoppers are significant in various industrial applications because of their influences on material characteristics and working parameters of the production process. In this paper, a rotating valve feeder, with eight vanes was investigated for transport action of bulk materials, such as wheat, maize and rice, which were ground, using the sieve sizes of 1, 3 and 5 mm. The rotating valve feeders under investigation have proven to be useful in transportation processes despite their construction simplicity. All investigations were done experimentally and numerically, using coupled Discrete Element Method (DEM) and Computational Fluid Dynamics calculation (CFD). The influences of different types of bulk materials and its particle size, on the performances of the rotating valve feeder during material transport were explored. The artificial neural network was developed (in the form of a multi-layer perceptron model) in order to optimize the granular flow of the bulk material, showing the high prediction capability of bulk density, dosing time and granular material flow, with the coefficient of determination equal to 0.999 during the training period. The decreasing of the sieve opening diameter caused the decrease in bulk density of the ground material, but statistically significant only for rice, as seen from the experiments and the results of the neural network model. The 5 mm sieve ensured the material with the highest flowability, significantly increasing the granular flow and decreasing the dosing time. The granular particles were modelled as the spheres in the DEM/CFD simulation, with a small-sized triangular surfaces. The DEM/CFD prediction of the mass transport for rice, wheat and maize was quite adequate, obtaining the coefficient of determination being 0.997; 0.998 and 0.849, respectively
Selected Aromatic Plants Extracts as an Antimicrobial and Antioxidant Finish for Cellulose Fabric- Direct Impregnation Method
No full textSix ethanolic extracts, obtained from anise, fennel, lavender, sage, mint, white horehound and their mixture were directly applied onto cellulose (viscose) fabric to impart antimicrobial and antioxidant functionality for its potential use as a wound dressing. Antimicrobial activity of treated fabrics against gram-positive bacteria S. aureus and yeast C. albicans, as common skin pathogens, was determined by agar diffusion test. The most effective against both microorganisms was viscose with anise, fennel, and mint, whereby clear inhibition and suppression zones were detected. The oxidation of viscose, intended to improve sorption properties and consequently adsorption of extracts, increased the antimicrobial activity of viscose with a mixture of extracts. The antioxidant activity of fabric samples with extracts, determined by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay, was significantly higher when compared to the untreated viscose sample (2.38 %) and ranged from 11.82 % for viscose with fennel up to 87.71 % for viscose with sage. Oxidation of fabric before sorption of extracts mixture contributes to higher antioxidant activity (68.81 %). Direct impregnation of bioactive plants extracts onto the fabric represents low cost and simple method, which makes it suitable for obtaining eco-friendly, low-cost disposable medical textiles with the therapeutic and prophylactic role