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排序方式: 共有690条查询结果,搜索用时 31 毫秒
21.
Ahmed M. Youssef Norbert H. Maerz 《Bulletin of Engineering Geology and the Environment》2012,71(1):171-186
The Missouri Rock Fall Hazard Rating System (MORFH RS) was recently developed for the State of Missouri. It is a system that
separates the risk of failure from the consequences of failure factors, thus allowing better assessment of the hazards of
rock falls. Efficiency is gained by video logging of highway rock cuts from vehicles moving at highway speeds, pre-screening
of rock cuts from video images, making some of the measurements needed for the rating system on digital images, and using
GPS receivers to collect field data and GIS to organize all the data. This paper describes the rationale behind the parameters
selected for the system using factor analysis and other methods and the verification of the system through sensitivity studies
and multiple rater tests. Simulations of remediation techniques were applied to recognize the most effective methods for remediation. 相似文献
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Peptidases occupy a central position in the enzyme market because of their importance in many areas, such as for physiological processes, foods, and detergents, as well as in the pharmaceutical, leather, and biotechnology industries. Microbial production is among the major sources of peptidases because it presents many advantages when compared with other methods. In this study, the metallopeptidases produced by the fungus Eupenicillium javanicum under a solid-state fermentation bioprocess were spray-dried. The enzymatic extract was dried using drying adjuvants, and optimal conditions for preserving enzymatic activity were studied following a Box-Behnken experimental design. The spray process factors studied were the air-drying temperature, enzyme feed flow rate, and the proportion of enzyme/additive. The responses analyzed were the dry extract yield and enzymatic activity after spray drying. Additionally, the stability of the dry extracts was assessed during 180 days at 4°C and 25°C. The results revealed extract yields of up to 66.12% and good enzymatic activity for intermediate values of temperature and adjuvant proportions. Furthermore, the dried enzymatic extracts showed potential for future commercial applications because of their stability at 25°C for 180 days. 相似文献
25.
Giuseppe Colla Youssef Rouphael Mariateresa Cardarelli Eva Svecova Elvira Rea Luigi Lucini 《Journal of the science of food and agriculture》2013,93(5):1119-1127
BACKGROUND: Cynara cardunculus is a species native to the Mediterranean basin. It includes globe artichoke and cultivated cardoon as well as their progenitor wild cardoon. The species is a source of biophenols, and its leaf extracts have been widely used in herbal medicine as hepatoprotectors and choleretics since ancient times. The aim of this study was to determine the effect of increasing the level of salinity in the nutrient solution (1 or 30 mmol L?1 NaCl) on biomass production, mineral composition, radical‐scavenging activity, caffeoylquinic acids and flavonoids in three artichoke (‘Romolo’, ‘Violetto di Provenza’ and ‘Violetto di Romagna’) and three cultivated cardoon (‘Bianco Avorio’, ‘Bianco Gigante Inerme’ and ‘Gigante di Romagna’) cultivars grown in a floating system. RESULTS: Increased salinity in the nutrient solution decreased the leaf dry biomass and leaf number of artichoke and cultivated cardoon cultivars. Salinity reduced macro‐ and microelement accumulation in leaves (e.g. N, K, Ca, Mg, Fe, Mn and B) but improved their antioxidant activity, total polyphenols, chlorogenic acid, cynarin and luteolin. The cultivated cardoons, especially ‘Bianco Avorio’ and ‘Gigante di Romagna’, showed higher biomass and leaf number than those observed in artichoke genotypes. ‘Violetto di Provenza’ exhibited the highest content of chlorogenic acid, closely followed by ‘Violetto di Romagna’, whereas for cynarin content the highest values were recorded in ‘Violetto di Provenza’, ‘Bianco Avorio’ and ‘Gigante di Romagna’. The highest content of luteolin was recorded in ‘Gigante di Romagna’ and ‘Bianco Avorio’, while the highest content of apigenin was observed in ‘Gigante di Romagna’. CONCLUSION: The results showed that the floating system could be considered an effective tool to improve quality aspects through proper management of the salt concentration in the nutrient solution. They also suggest that specific cultivars should be selected to obtain the desired profile of bioactive compounds. © 2012 Society of Chemical Industry 相似文献
26.
Investigation of Heat‐Induced Degradation of Virgin Olive Oil Using Front Face Fluorescence Spectroscopy and Chemometric Analysis 下载免费PDF全文
Yvon Mbesse Kongbonga Hassen Ghalila Youssef Majdi William Mbogning Feudjio Zohra Ben Lakhdar 《Journal of the American Oil Chemists' Society》2015,92(10):1399-1404
A simple setup using a 365‐nm light‐emitting diode coupled to a USB spectrometer through an optical fiber, in a front‐face fluorescence configuration, was used to investigate the heat‐induced deterioration of virgin olive oil at different heating temperatures and times. The samples were heated for 30, 60, 120 and 180 min for every temperature setting of 140, 160 and 180 °C, respectively. Two important results are reported in this article. First, a neo‐formed compound around 665 nm due to the degradation of chlorophyll was observed. This new peak was attributed to pyropheophytins. The second result showed an important rise of the peak around 489 nm, which corresponded to the oxidation products. The correlation obtained between the peroxide value and the 489 nm peak using principal component analysis revealed the mechanism of the oxidation process. It further showed that the peak around 489 nm is a direct consequence of the degradation of hydroperoxide. 相似文献
27.
Beya Haouas Taieb Saied Hanen Ayari Youssef Arfaoui Mohamed Lamine Benkhoud Khaled Boujlel 《Journal of Sulfur Chemistry》2016,37(4):391-400
Electrogenerated cyanomethylanions obtained by reduction of dry acetonitrile at a steel grid cathode were used to promote the addition of ethyl bromoacetate to thiourea derivatives. The reaction yields the corresponding 2-imino-1,3-thiazolidin-4-one. The reaction pathway was discussed based on the kinetic and thermodynamic data obtained by computational methods. In addition, the biological activity of these new compounds was also investigated. 相似文献
28.
Hasanin Mohamed Sharmoukh Walid Hassan Youssef R. El Saied Houssni 《Journal of Inorganic and Organometallic Polymers and Materials》2022,32(2):667-677
Journal of Inorganic and Organometallic Polymers and Materials - Historically, the recording of information over paper has always been regarded as the most important factor for maintaining records... 相似文献
29.
Amna Youssef Ramzy Ahmed Mohammed Moneeb El‐Sabbagh Leif Steuernagel Gerhard Ziegmann Dieter Meiners 《应用聚合物科学杂志》2014,131(3)
The presented study investigates the flow length and the corresponding fiber content distribution in the injection‐moulded natural fiber reinforced thermoplastics and its relation to fiber type and processing parameters such as injection pressure, temperature, injection rate and mould tempering by increasing die temperature. In this research, polypropylene compounds with nominally 30 wt % hemp and sisal fibers are investigated. The influence of the injection pressure (500 and 1000 bar), melt temperature (180°C, 200°C, and 220°C), and die temperature (23°C and 80°C) on the fiber content distribution all over the sample is investigated. An increasing linear trend of fiber content along the spiral length is observed as an evidence of a fiber/polymer multiflow system. A pattern for fiber content distribution with respect to the fiber length along the injected spiral can be distinguished, where the longer fibers are usually found at the end of the injected part and the shorter fibers remain near mould entrance point. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39861. 相似文献
30.
Emna Hmani Sourour Chaabane Elaoud Youssef Samet Ridha Abdelhdi 《Journal of hazardous materials》2009,170(2-3):928-933
Electrochemical oxidation of O-Toluidine (OT) was studied by galvanostatic electrolysis using lead dioxide (PbO2) and boron-doped diamond (BDD) as anodes. The influence of operating parameters, such as current density, initial concentration of OT and temperature was investigated. Measurements of chemical oxygen demand were used to follow the oxidation. The experimental data indicated that on PbO2 and BDD anodes, OT oxidation takes place by reaction with electrogenerated hydroxyl radicals and is favoured by low current density and high temperature. Furthermore, BDD anodes offer significant advantages over PbO2 in terms of current efficiency and oxidation rate. 相似文献