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101.
102.
Taârit MB Msaada K Hosni K Marzouk B 《Journal of the science of food and agriculture》2012,92(8):1614-1619
BACKGROUND: Hydroponic culture was used to investigate the effect of NaCl concentrations on the growth, nutrient uptake, phenolic content and antioxidant activity of Salvia officinalis L. leaves. The antioxidant capacity of the methanolic extract of S. officinalis was evaluated by using 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging test and β‐carotene‐linoleic acid bleaching assay. Physiological and biochemical parameters of S. officinalis were assessed after 4 weeks of salt treatment with 0, 25, 50, 75 and 100 mmol L?1 NaCl. RESULTS: Plant growth exhibited a reduction of 61% at 100 mmol L?1 NaCl. Assessment of Na+, K+ and Ca2+ and water contents of shoots and roots showed that S. officinalis is able to regulate Na+ concentration by active compartmentation in vacuoles. Salvia officinalis phenolics were increased in response to salinity at the threshold of 75 mmol L?1 NaCl. This herb was also found to be able to achieve important DPPH? quenching activity and to inhibit the β‐carotene‐linoleic acid bleaching notably enhanced by salt treatment. It is interesting to highlight the correlation between the phenolic and antioxidant activity, suggesting the involvement of these compounds in this activity. CONCLUSION: Salvia officinalis treated with 75 mmol L?1 NaCl constitutes a potential source for production of secondary metabolites useful in several applications. Copyright © 2011 Society of Chemical Industry 相似文献
103.
In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel 下载免费PDF全文
Taísa Penazzo Lepri Renata Siqueira Scatolin Vivian Colucci Adílis Kalina De Alexandria Lucianne Cople Maia Cecília Pedroso Turssi Silmara Aparecida Milori Corona 《Microscopy research and technique》2014,77(8):586-593
The present study aimed to evaluate in situ the effect of CO2 laser irradiation to control the progression of enamel erosive lesions. Fifty‐six slabs of bovine incisors enamel (5 × 3 × 2.5 mm3) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO2 laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO2 laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2‐day lead‐in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross‐over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three‐way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO2 laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO2 laser irradiation was performed. There was no difference in enamel wear between specimens CO2‐laser irradiated and non‐irradiated (P = 0.513). Under intraoral conditions, CO2 laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. Microsc. Res. Tech. 77:586–593, 2014. © 2014 Wiley Periodicals, Inc. 相似文献
104.
105.
In this study, optimization of some parameters of stirred mill on ultra-fine grinding of refractory Au/Ag ores was performed. A three-level Box-Behnken design combining a response surface methodology (RSM) with quadratic programming (QP) was employed for modelling and optimization of some operating parameters in ultra-fine grinding. Grinding tests were carried out in a laboratory scale pin-type vertical stirred mill. The relationship between the response, i.e. d80 size, and four grinding parameters, i.e. ball diameter, grinding time, ball charge ratio and stirrer revolution was presented as empirical model equations. Analysis of variance showed a high coefficient of determination value (R2 = 0.9698), thus ensuring a satisfactory of the second-order regression model with the experimental data.The model equations were then optimized using the quadratic programming method to minimize for d80 size within the experimental range studied. The optimum conditions were found to be 1.61 mm for ball diameter, 11.50 min for grinding time, 80% for ball charge ratio and 745 rpm for stirrer revolution for this grinding process.In order to verify the improvement of grinding performance using the optimal level of control factors three verification experiments were conducted, and the results for d80 was 3.37 μm, which were smaller than those obtained in the initial tests. 相似文献
106.
The adsorption behavior of cesium on poly(N-isopropylacrylamide/itaconic acid) copolymeric hydrogels
In this study, N-isopropylacrylamide/itaconic acid (NIPAAm/IA) hydrogels prepared by irradiating with γ radiation were used in experiments on cesium ion adsorption. The cesium ion adsorption capacity of the hydrogels was investigated as a function of Cs+ concentration, pH and temperature. The adsorption behavior of cesium was evaluated by using the radiotracer method. The adsorption isotherm models were applied to the experimental data, and it was seen that Freundlich isotherm explained the adsorption better than Langmuir isotherm. Two simplified kinetic models including pseudo-first-order and pseudo-second-order equation were selected to follow the adsorption processes. The Cs+ adsorption could be best described by the pseudo-first-order equation. The thermodynamic parameters including ΔG°, ΔH° and ΔS° for adsorption processes of Cs+ on the hydrogel were also calculated, and the negative ΔH° and ΔG° confirmed that the adsorption process was exothermic and spontaneous. 相似文献
107.
A Platinum-modified alloy coating with high hydrogen evolution reaction (HER) durability activity was prepared by electrodeposition. The durability of this catalyst was determined with electrolysis technique for 120 h. The prepared electrode was characterized by energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Long-term electrolysis was carried out in 1 M KOH solution by cathodic current–potential curves and electrochemical impedance spectroscopy (EIS). Experimental result showed that CoZn–Pt coating has a rough structure and presents good stability and high durability. Electrochemical activity increases slightly with increasing electrolysis time. High durability of Pt modified cathode was attributed to the high surface area and synergistic interaction between Co, Zn and Pt. 相似文献
108.
在无煮茧自动缫丝工艺的基础上,采用不同茧质的原料进行实缫试验,探讨了磺化蓖麻油助剂对缫丝成绩的影响。试验结果表明:磺化蓖麻油助剂可提高无煮茧自动缫丝工艺的解舒率,降低万米吊糙次数、减小最大偏差和均方差、增加台时产量、提高清洁和洁净,使生丝的综合等级平均提高了0.64 A。磺化蓖麻油无煮茧自动缫丝工艺继承了无煮茧自动缫丝工艺的全部优点,并克服了无煮茧工艺对解舒成绩较差的原料茧不宜使用的不足,利用磺化蓖麻油助剂来改善无煮茧自动缫丝工艺的缫丝性能具有很大的可行性。 相似文献
109.
Effects of different sulphur dioxide (SO2) concentrations (188, 452, 791, 1,034, 1,236, 2,899 and 3,864 mg SO2 kg?1) and storage temperatures (5, 10, 20 and 30 °C) on the physical, chemical and microbial qualities of sulphited-dried apricots (SDAs) were evaluated. Analysis of kinetic data suggested first-order models for losses of moisture and SO2 and formation of brown colour. Strong correlations were found between SO2 concentrations and moisture loss constants (r?=??0.943), and brown colour values (r?=?0.949). β-carotene contents in SDA samples ranged from 26.6 to 36.2 mg 100 g?1 dry weight, depending on SO2 content of dried apricots. The SO2 concentration over 791 mg per kg of dried apricots effectively protected carotenoids in dried apricots during drying. While storage times had significant effect on β-carotene contents, storage temperatures did not have such effects. The number of total mesophilic aerobic bacteria in all SDA samples ranged from 8.20?×?101 to 1.84?×?102 CFU g?1. The number of total psychrophilic aerobic bacteria, lactic acid bacteria, yeast and mould, xerophilic mould, Staphylococcus spp. and total Enterobacteriaceae were below the detection limits (<4 CFU g?1) in samples containing SO2 even at the lowest level (188 mg SO2 kg–1) throughout the storage. Regardless of SO2 concentration in dried apricots, low storage temperatures (below 20 °C) should be preferred to prevent the characteristic golden yellow colours of dried apricots. 相似文献
110.
采用氯化钙溶解废弃蚕丝制备可溶性丝蛋白,考察了透析时间与溶解废丝量对蛋白质质量分数、钙离子含量及表面性能的影响。实验结果表明:透析时间对蛋白质质量分数变化影响较小,钙离子含量在6~18 h有较快的变化,18 h后变化变缓,而钙离子含量随废丝量增加而增加。乳化性在透析时间24 h时最好,几乎达到100%;起泡性随透析时间变化较小,起泡性在200%左右,而泡沫稳定性在12 h最高为87%,随后略有降低;随废丝量的增加其乳化性增加,溶解废丝量15 g时,乳化稳定性最高为89%,起泡性和泡沫稳定性随废丝量增加而增加,起泡性最高达到224%,泡沫稳定性可达到85%。 相似文献