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关键词： Electron beam   Pulsed plasma chemical method   Electrospark method   Zinc oxide   Titanium dioxide  

摘要： In this study, particles of titanium dioxide (TiO2) were modified with particles of zinc oxide (ZnO) using a pulsed plasma chemical method, with ZnO initially being obtained by an electrospark method. The particle size of the synthesized TiO2 powder modified with ZnO nanoparticles ranged from 30 to 100 nm. The morphology of the nanoparticles was found to be diverse, mainly represented by spheres, ovals, and parallelograms. The phase composition was a mixture of crystalline phases characteristic of TiO2 (rutile and anatase) and ZnO, with the predominant phase being anatase. The presence of Zn-O-Ti bond is typical for all samples of TiO2 powder modified with ZnO nanoparticles prepared using a pulsed plasma chemical synthesis, which indicates the formation of a solid solution. The optical and photocatalytic properties of the modified nanoparticles were also studied, as well as the band gap was determined. For some samples, a narrowing of the band gap was recorded. The samples showed high photocatalytic activity in the decomposition of methylene blue under the influence of ultraviolet and visible light in the wavelength range of 400-630 nm. Methylene blue degradation efficiency was 66% in visible light spectrum.

关键词： Nanotechnology   Titanium dioxide nanoparticles   Wheat   Drought stress  

摘要： Drought stress is reducing the production of crops globally. This research was designed to evaluate the role of titanium dioxide (TiO2 NPs) nanoparticles and calcium phosphate on wheat facing drought stress. TiO2 NPs were prepared by green synthesis and their characterization (by UV-visible spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX)) was also done. The results showed that TiO2 NPs worked efficiently and improved plant growth under drought. However, the best results were obtained from combined applications of 40 ppm TiO2 NPs and 40 ppm calcium phosphate on plants. They increased root length (33%), shoot length (53%), fresh weight (48%), and dry weight (44%) of wheat as compared to control. The physiological parameters including chlorophyll content, relative water content, membrane stability index, and osmolyte content (proline and sugar) were also improved. The increase in superoxide dismutase, peroxidase and, catalase activity by the combined application of TiO2 NPs and calcium phosphate was 83% and 78%, 74% and 52%, 81%, and 67% in Pakistan-13 and Zincol-16 respectively, as compared to untreated drought exposed plants. They also enhanced the nutrients uptake (including potassium, phosphorus, and nitrogen) that ultimately improved plant biomass. They also maintained the level of growth hormones in plants. These hormones regulate cellular processes and are responsible for germination, development, and plant reaction in drought stress. The increase in the yield was also significant, hence it is recommended that the 40 ppm concentration of TiO2 NPs along with calcium phosphate improves the productivity of wheat under drought stress.

关键词： Capsicum chinense   Organic fertilization   Agroecology   Preference  

摘要： Biquinho pepper has been gaining prominence on the national scene because of its sweet taste and low pungency. This study evaluated the effect of liquid biofertilizer on the quality of the Biquinho pepper. Three treatments were tested: Biquinho pepper with mineral fertilizer (T1), biofertilizer (T2), and control (without fertilizer) (T3), totalizing 12 plots. The agronomic parameters were evaluated, as well as those regarding fruit and plant production, physicochemical characteristics (chlorophyll;humidity;titrable acidity;soluble solids;pH, firmness, ascorbic acid, instrumental color), and sensory analysis. For the production parameters (fruit weight and mass), the treatment using liquid biofertilizer was superior compared to the others. Regarding the dimensional variables of the fruit (length, diameter, mass, and wall thickness), the control presented significantly inferior results, besides lower chlorophyll content. The peppers produced using mineral fertilizer presented higher acidity contents, together with the control, and lower pH. There was no significant difference among the treatments regarding the contents of humidity, soluble solids, firmness, and ascorbic acid. Regarding instrumental color, only the attribute chroma (color saturation) of the fruit from the control treatment presented superior values. In terms of size and crunchy texture, the fruit from the treatment with biofertilizer presented the greatest sums, but not interfering in preference. The liquid biofertilizer was observed as a satisfactory alternative for Biquinho pepper production.

关键词： Euryale ferox   Resistant starch   Structural characterization   Physicochemical properties   In vitro digestive properties  

摘要： At present, the raw materials for industrialized RS3 products are relatively simple and its purity is low. In addition, the correlation between structure and digestion characteristics of RS3 are rarely studied. In this study, euryale ferox, a kind of annual aquatic herb crop with high content of starch was used as a raw material to prepare RS3 by different methods, including autoclaving, enzymolysis-autoclaving and dual enzymolysis, respectively. The results showed that there were significant differences in the structure and physicochemical properties of the different euryale ferox resistant-enhanced and purified resistant starches (p < 0.05). Purified euryale ferox resistant starches belonged to B + V type crystal and had high thermal stability. After digestion, the structure and thermal properties of euryale ferox resistant-enhanced starches changed a lot. The digestion rate and estimated glycemic index (eGI) of the three kinds of purified euryale ferox RS3 were lower than 20% and 50%, respectively.

关键词： Endodontic surgery   Strontium fluoride   Bismuth oxide   Zirconium dioxide   Radiopacifier   Hydroxyapatite  

摘要： The purpose of this study was to investigate the influence of different radiopacifiers on the physicochemical and biological properties of novel calcium silicate based endodontic ceramic enriched with bioactive nanoparticulated hydroxyapatite - ECHA. Namely, ECHA was used as a basis for mixing with the following radiopacifiers: strontium fluoride (SrF2), zirconium dioxide (ZrO2) and bismuth oxide (Bi2O3). For comparison, Portland cement (PC) and mineral trioxide aggregate (MTA) were used. The following physicochemical characteristics were examined: the radiopacity, setting time, compressive strength, porosity, wettability and pH value. The biocompatibility of the cements was assessed by crystal violet, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) and cell adhesion assays. The highest radiopacity was obtained for the ECHA + Bi2O3 mixture and MTA that were statistically significant in comparison to other materials (p < 0.05). Both initial and final setting times as well as compressive strengths were statistically lower for experimental cements than for PC and MTA (p < 0.05). The lowest total porosity was observed in the ECHA + ZrO2 group when compared with the other two experimental cements (p < 0.05), but not when compared with PC and MTA (p > 0.05). Experimental cements exhibited statistically higher contact angles of glycerol than PC and MTA (p < 0.05). For blood plasma, a statistical difference was found only between ECHA + Bi2O3 and PC (p < 0.05). All investigated materials had alkalization ability. Cell viability assays revealed that the extracts of tested cements did not exhibit cytotoxic effect on L929 cells. Scanning electron microscopy had shown a high degree of cell proliferation and adhesion of cells from apical papilla on experimental cements' surfaces. Novel endodontic ceramics with nano-hydroxyapatite addition have satisfactory biological and physicochemical properties when compared to MTA and PC controls. Considerable lower setti

关键词： Fly ash geopolymer   Strength   Ambient curing   Silicate  

摘要： High strength ambient cured alkali-activated cement was developed from original Class-F (ASTM) fly ash using 1:2.5 mass ratio of 16 molar sodium hydroxide and sodium silicate liquid activator with solution to solid binder ratio of 0.36 for in-situ cast application. Graded strength of high, medium and low in the range of 60-103, 30-56 and < 20 MPa were obtained using mono-component original fine, medium and coarse sized fly ashes respectively. The inclusion of 35 wt% GGBS in the medium sized Class-F fly ash improved the strength from 45 MPa to 60 MPa while 100% GGBS showed higher strength of 81 MPa. Chemically, CaO/SiO2 ratio in the composition influenced the fresh and hardened properties of alkali-activated fly ash/GGBS cements. For instance, in the Class F fly ash (Si/Al=1.55-1.99) based compacts with CaO/SiO2 ratio < 0.03, the strength improved with increasing atomic Al/(Na + K) ratio. Conversely strength decreased with increasing Al/(Na + K) ratio in bi-component fly ash and GGBS based alkali-activated cements where CaO/SiO2 ratio is higher in between 0.17-0.75. Interestingly Si-dissolution from subcrystalline silica or fine quartz from mechanically activated Class-C fly ash did not improve strength. Lignite ash with high specific surface area as obtained in low temperature combustion did not react with high pH alkaline solution indicating need for vitreous aluminosilicate glass. X-ray diffraction and attenuated total reflectance Fourier transform infrared spectroscopic analyses show that plagioclase and C-S-H were the reaction products responsible for strength gain in ambient cured alkali-activated fly ash/GGBS cements.

关键词： Dielectric parameters   Optical properties   Crystallinity   Composite  

摘要： An investigation on relationship among the physicochemical, optical and dielectric properties of the hydroxyapatite/cornstarch (HA/Cs) composites with the starch proportion of 30, 40, 50, 60, 70, 80 and 90 wt% is presented in this work. The HA/Cs composites have been characterized via FTIR, XRD, DRS and impedance analyzer. This work depicts that the strong interaction is exhibited between the hydroxyapatite nanoparticles and starch as the starch proportion increases. This increment trend results in the higher crystallinity of the HA/Cs composites. The highly crystallized HA/Cs with hydroxyapatite nucleation center presents low optical properties (diffuse reflectance and optical band gap energy). The HA/ Cs composite with 80 wt% starch proportion (H2C8) show higher dielectric properties (dielectric constant, loss factor and conductivity) due to the stronger interfacial interaction and close-packed HA/Cs crystalline structure. The relationship among the physicochemical, optical and dielectric properties of the HA/Cs composite is studied in this work for potential of instrumentation design. (c) 2021 Elsevier Inc. All rights reserved.

关键词： differential scanning calorimetry   functionalization of polymers   lipids   optical properties   thermogravimetric analysis  

摘要： Chia oil has a high content of linolenic and linoleic acids, which are essential for the human body. However, their high degree of unsaturation (double bonds) makes the oil very susceptible to oxidation. In this context, the use of spray drying can be useful strategy to minimize the oxidation of this oil. Thus, the aim was to assess the effects of inlet temperature and feed rate conditions involved in the spray drying process on the physicochemical and morphological characteristics, and stability of the chia oil microparticles with maltodextrin and GA. The microparticles were obtained with a yield of 50%, encapsulation efficiency greater than 87%, low-moisture content, and mean particle sizes ranging from 3.01 to 4.11 mu m. The thermal evaluation and storage evidenced an increase in stability. The H-1 HR-MAS NMR technique showed that the microparticles maintained the characteristic fatty acid profile of chia oil and seeds. Results indicate that the microencapsulation methodology was suitable for preparing microparticles containing chia oil.

关键词： Anti-E   coli activity   Essential oil mixture   Nanoemulsion   Physicochemical characterization  

摘要： This research studies the application of a specific nanoemulsion as anti-Escherichia coli agent. The specific mixture was generated by a simplex-centroid design. Physicochemical parameters such as droplet average diameter, pH, viscosity, density, turbidity, whitening index, refractive index, stability (thermal, physical, and osmotic stability), and antibacterial activity kinetic, have been assessed. The mixture nanoemulsions had droplet diameters significantly smaller than those of clove or cinnamon nanoemulsions. Individual and mixture essential oils nanoemulsion exhibited appropriate stability under pH, thermal, and ionic stress as well as after mid-term storage. Antibacterial activity kinetic revealed the fast and pronounced efficacy of mixture nanoemulsions on E. coli (reach 98% of growth inhibition), especially for the nanoemulsion composed of 50% essential oil in the dispersed phase upon 20 days of storage. All data considered, the actual work evidences the promising advantages of using specific nanoemulsions as delivery systems of antibacterial agents in the beverage and food industry.

关键词： Non-thermal plasma   Alumina   Dry reforming   Methane  

摘要： Macro-mesoporous alumina, calcined at different temperatures (from 400 to 800 degrees C), were tested in dry reforming of methane reaction under plasma discharge at a fixed deposited power (P = 8 W) with a ratio CO2/CH4 = 2. Besides alumina materials, the one possessing the lowest surface area (72 m(2) g(-1)) exhibited the highest activity: Methane conversion reaches 31.3 % against 23.4, 22.6 and 26.8 % for alumina calcined at 400, 600 and 800 degrees C, respectively, suggesting that the active sites generated into the mesoporosity of alumina (Al2O3 400) are not accessible to reactants under the plasma discharge. Reactant transformation is promoted with the alumina possessing the highest number of acid and basic sites and a correlation is proposed. It is believed that CH4 and CO2 adsorption are improved over acid and basic sites at the surface of alumina, favoring the production of syngas.