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关键词： hydrogel   arabic gum   PEGDMA   drug delivery   mechanical strength  

摘要： Hydrogel development using natural and synthetic polymers for biomedical applications have shown promising properties for drug delivery due to virtuous stimuli response and improvement in mechanical strength. Biomaterial hydrogel was synthesized using combination of arabic gum (AG), a natural polymer and polyethylene glycol dimethacrylate (PEGDMA), a synthetic polymer. The synthesis process follows chemical cross linking by free radical polymerization. Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and differential scanning calorimetry (DSC) were used to characterize the hydrogels. Product yield, gel content and gelation time depends solely on the variable reacting concentrations and the mechanical properties of hydrogel depends on its compositions. Swelling studies reveal high swelling ratio in buffer solution pH 1.2 compare to buffer solution pH 7.4, and deionized water at pH 6.7. Swelling ratio raises with increase in PEGDMA concentration, but the presences of salt/ions solutions decreases the swelling ratio significantly and it depends on the charge of the ions. The kinetics of the swelling follows a second order non-linear rate equation. The rate of degradation revealed significant degradation in acidic medium and insignificant degradation was observed in basic medium. The encapsulation efficiency of quercetin introduced directly in the hydrogels during synthesis was found in the range of 85-94%. The release profile indicates the dependence of arabic gum grafted PEGDMA hydrogels on pH and compositions. The characteristic properties exhibited by the formulated hydrogels suggest the suitability of them to be applied as drug carriers.

关键词： Honey   Mead   Alcoholic beverage   Aroma-active compounds   Antioxidant properties   Sensory evaluation   Hydroxymethylfurfural  

摘要： Background: Mead is a traditional alcoholic beverage obtained by fermentation YYof mead wort and is popularly produced at home and/or in small meaderies. Different types of mead can be distinguished based on honey-to water ratio, addition of spices and/or fruits, and the method of wort preparation. The consumption of mead has gained popularity in Europe owing to the presence of its natural and high-quality compounds. As a result, mead production has remarkably increased during the past years, and increasing attention has been paid to improve its production parameters. Scope and approach: In the first part of this comprehensive review, general aspects of mead production and the characteristic parameters of alcoholic beverages, including organic acid content, pH value, ethanol content, titratable acidity, volatile acidity, and residual sugar content are discussed. In the second part, the aroma profile and sensory acceptability of mead, including parameters that might influence the characteristic aroma of mead, is presented. Key findings and conclusions: The flavor of mead mainly depends on the type of honey used for fermentation, and the analysis of odorants is one of the most important criteria in the quality evaluation of mead. In addition, the presence of hydroxymethylfurfural, one of the major Maillard reaction products, and of phenolic compounds is related to the type of honey used. Furthermore, the antioxidant activity of mead significantly correlates with the type and amount of honey used for mead preparation.

关键词： Single crystals  

摘要： The synthesis and characterization of organic nonlinear optical active (NLO) single crystal ofl-threoninium succinate (LTS) were carried out in this work. LTS crystal was prepared by slow evaporation technique using deionized water as solvent in a period of 82 days and the obtained LTS crystal was subjected to such characterizations as single-crystal X-ray diffraction analysis, UV-Vis-NIR spectroscopy analysis, FT-IR spectrum analysis, thermal analysis, second harmonic generation, and surface quality analysis. The third-order nonlinear optical properties of the LTS crystal were estimated at 532 nm using semiconductor laser source. Then it was employed for Z-scan analyzer to sense the nonlinear refractive index (n(2)), absorption coefficient (beta), and third-order susceptibility (chi(3)). Through this analysis, this research calculated then(2) = 2.35 x 10(-15)(m(3)/W),beta = 1.3057 x 10(-8)(m/W), and chi(3) = 1.0571 x 10(-13)(esu) were determined. The obtained results exhibited an appropriate variation in optical limiting behavior of the LTS material which saturates at higher intensities with respect to input and output power. The laser damaged threshold (LDT) technique enables the great resistivity toward optical high energy and it is found to be 52.7 mJ.

关键词： Polyunsaturated fatty acids  

摘要： Raw goat milk was treated with a continuous mode of pulsed electric field (PEF) system, at three levels of field strength (20, 30, and 40 kV/cm) with monopolar square-wave pulses of 5 and 10 mu s treatment time. The physicochemical properties, particle size distribution, fatty acid profiling, and metal migrations of untreated and PEF-treated goat milk were evaluated. The results indicated that PEF-treated goat milk (40 kV/cm;10 mu s) had significant changes (p < .05) in pH and titratable acidity value of the samples due to the decrease in calcium ion (Ca2+), which leads to the protonation of the phosphate. The specific surface area (SSA) value significantly increased (p < .05) with the increase of PEF treatment time. PEF treatment was shown to reduce (p < .05) the total saturated fatty acids ( n-ary sumation SFAs) and total polyunsaturated fatty acids ( n-ary sumation PUFAs) of goat milk, while total monounsaturated fatty acids ( n-ary sumation MUFAs) were increased. The disintegration of fat and triacylglycerol breakdown from the fat globule (FG) membrane, together with heterogeneous metal catalysis oxidation may have caused the degradation of certain fatty acids (p < .05) in the study. Mean concentrations of micro-elements (Fe, Cr, Mn, and Ni) in all PEF-treated samples were within the permissible limit of heavy metals according to the USFDA drinking water quality standard. Practical applications PEF is an emerging alternative pasteurizing method, when applied correctly could prolong the shelf-life, while lessening the detrimental impacts on the organoleptic properties of goat milk. The results show that pasteurization via monopolar PEF can be recommended to enhance the quality of goat milk at the industry level.

关键词： Spray-drying   Peptide fractions   Flaxseed   Antioxidant activity   Surfactant   Stability  

摘要： Spray-drying is an effective method in increasing the physicochemical stability and preserving the biological activities of bioactive compounds. However, shear tension and dehydration during spray-drying, and localization of peptides at the water/air interface, leads to their structural instability, thermal damage and loss of their biological activity. In the current research, fractionation of hydrolyzed flaxseed proteins to different molecular weights (10, 30 and 100 kDa) was performed. Then, the peptide fraction with highest antioxidant activity was selected and influence of surfactant (Tween-80) combined with maltodextrin (MD) on production yield, physical stability, antioxidant activity and morphological properties of microencapsulated particles was analysed. Antioxidant features of peptides were affected by their molecular weight and amino acid composition. Using surfactant + MD, significantly led to a lower hygroscopicity (from 42 to 23%), higher production yield (from 37 to 54%), and better retention of radicals-scavenging activity of DPPH (80.3%), ARTS (92.3%), hydroxyl (97.9%), nitric oxide (82.3%), reducing power (98.7%), total antioxidant activity (98.3%), chelating activity of iron (97.6%) and copper (97.5%) proxidants by spray-dried peptides. Also, the use of Tween-80 in feed formulation through competitive surface migration with peptides resulted in the production of spherical particles with relatively smooth surfaces, as revealed by SEM images. Therefore, surfactants can be used as a strategy to increase the biological stability of various food and pharmaceutical peptides during spray-drying encapsulation.

关键词： FLASH   High dose-rate   Peroxyl radicals   Recombination   Protontherapy   Modelling  

摘要： Background and purpose: FLASH radiotherapy, a technique based on delivering large doses in a single fraction at the micro/millisecond timescale, spares normal tissues from late radiation-induced toxicity, in an oxygen-dependent process, whilst keeping full anti-tumor efficiency. We present a theoretical model taking into account the kinetics of formation and decay of reactive oxygen species, in particular of organic peroxyl radicals ROO center dot formed by addition of O-2 to primary carbon-centred radicals R-center dot and known to play a major role at the origin radio-induced complications. Materials and methods: The model focuses on the time-dependent evolution of radiolytic products in living matter exposed to continuous irradiation at dose-rates in the range 10(-3) - 10(7)Gy center dot s(-1). The 9 differential rate equations resulting from the radiolytic and enzymatic reactions network were solved using the published values of these reactions rate constants in a cellular environment. Results: The model suggests a correlation between the area-under-the-curve of time-evolving [ROO center dot] and the probability of normal tissue complications. The model does not lend weight to the hypothesis of transient oxygen depletion as a main determinant of FLASH but rather suggests a major role of radical-radical recombination. Conclusion: The model gives support to the reduction of ROO center dot lifetime as the main root of FLASH and compares favorably with published experimental results. We conclude that any process - in this case radical recombination - that shortens the lifetime or limits the radiolytic yield of ROO center dot is likely to protect normoxic tissues against the deleterious effects of radiation. (C) 2020 The Author(s). Published by Elsevier B.V.

关键词： Putrescine   Spermine   Monochlorobimane   2, 7-Dichlorofluorescein   Meloidogyne incognita   Tomato   Anti-oxidants   Stress indices  

摘要： Root-knot nematodes are one of the important phytoparasites that adversely affect the growth and development in plants, thus affecting its productivity. Various chemical nematicides are available commercially, having adverse effect on the environment and non-target organisms. So, it becomes necessary to explore some eco-friendly strategies to manage these parasites. Polyamines recognised as potential phytohormone, enhance the plant survival during stressful conditions. Thus, present study was undertaken to evaluate the stress protective properties of two polyamines in tomato seedlings under nematode stress. Uniform sized tomato (cv. Pusa Ruby) seeds were sterilized and treated with different concentrations (0.5, 0.7 and 0.9 mM) of two polyamines i.e. putrescine and spermine. Seeds are allowed to germinate in in-vitro conditions and subjected to nematode inoculation with second stage juveniles of Meloidogyne incognita @5J(2)s per seedlings after germination. Various morphological and biochemical parameters were analysed after one day of nematode inoculation. Nematode invasion alters the morphological and biochemical parameters whereas polyamines treatment restores them to control level. Significant decrease in specific activities of antioxidative enzymes viz: superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, glutathione peroxidase, polyphenol peroxidase, and pyrogallol peroxidase was observed in polyamines treated seedlings except guaiacol peroxidase and phenylalanine lyase with maximum activity change by spermine application comparing with nematode inoculated seedlings. Chlorophyll content also increases significantly with spermine treatment. Non-enzymatic antioxidants analysis also revealed the anti-stress properties of polyamines as the total phenolic, ascorbic acid content significantly increases whereas decreased glutathione content was observed with polyamine application. Results obtained from confocal microscopy also revealed the inh

关键词： Aerogel Fe-ZrO2   Amount of Fe   Toluene oxidation   Water vapor  

摘要： In this work, a series of xFe-ZrO(2)aerogel catalysts, with different amounts of iron were prepared and tested in the total oxidation of toluene. The xFe-ZrO(2)aerogel catalysts obtained demonstrate the diffraction peaks of ZrO(2)tetragonal phase and a high surface area and porosity. The iron content influences the physicochemical and catalytic properties of the samples. Among the iron-based catalysts, the one with 5% Fe shows the best activity between 300 and 550 degrees C with 96% C6H5-CH(3)conversion to CO(2)at 550 degrees C.

关键词： iodine-131   volumetric activity   aerosol   gaseous emissions   physicochemical forms of radioactive iodine   filter pack  

摘要： On the basis of the recommendations of the IAEA and the requirements of domestic regulatory documents, a study is conducted to determine the activity of aerosol and gaseous forms of I-131 compounds in a gas-aerosol mixture of emission from an industrial reactor facility (hereinafter referred to as IRF). Three types of packs of analytical filters are used as an adsorption-filter material. Under normal operating conditions, a series of sampling procedures is performed at a point in front of the gas cleaning system. The investigations have made it possible to determine the dominant physical form of I-131 in the high-pressure gas holder. It is shown that, in a gas-aerosol mixture prior to the IRF gas cleaning system, the volumetric activity of iodine is determined mainly by hardly adsorbed gaseous compounds. The ejector gases contain iodine-131 compounds, which are hardly adsorbed on silver nitrate impregnate. The obtained data will be used in designing the cleaning systems for new IRFs of a similar type.

关键词： Fish oil biodiesel   Neutralization oil   Refinement oil   Transesterification  

摘要： Crude oil extracted from tilapia heads and oils obtained from different steps of its refinement process (physically degummed, chemically degummed, neutralized, and bleached oils) were used as raw materials for biodiesel production. Extraction and refinement of the oil and, after, production and economic viability of the different biodiesels were performed. The heads corresponded to 45% of waste from Nile tilapia and of extractions yield was around 80-85% of the crude oil. The highest biodiesel yields were with the neutralized oil (80.35%, w w(-1)) and chemically bleached oil (83.55%, w w(-1)). The lowest biodiesel production costs were by the physical degumming, chemical degumming, and neutralization steps, which presented an average cost of 0.181 US$ kg(-1). Neutralized oil in the transesterification reaction, besides presenting the lowest biodiesel production cost, provided a suitable product with the acid value, kinematic viscosity, and flash point according to ASTM standard for biodiesel. Regardless of the refinement process, the degradation ranges of the oil samples were 350-550 degrees C. TLC, GC, and FTIR confirmed the triglycerides conversion from tilapia oil into biodiesel. Based on results, Nile tilapia neutralized oil showed suitable characteristics, becoming a promising source for biodiesel production of the quality and economically viable. (C) 2020 Elsevier Ltd. All rights reserved.