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51.
Phosphatic materials of agronomic interest were synthesised. These materials of good mechanical quality and of significant porosity show high P2O5 contents (up to 28%). They have been prepared by treatment of volcanic pumices with a solution of phosphoric acid (1N, 5N or 10N) at 200°C in a closed system for 72h using a mass solid/liquid ratio of 1:3.After reaction, the precipitation of amorphous phosphates and crystalline aluminium phosphates has been detected by XRD both outside and inside of the material. The morphological study by SEM reveals several crystalline forms of aluminium phosphates: crystals of small size migrate into the internal porosity of the pumices and crystals of berlinite appear (AlPO4) well developed in a matrix of amorphous phosphate overlapping the initial material.Normal tests of reactivity in water and in 2% citric acid show that the percentages of released P2O5 in solution are greater after treatment with weak concentrations of phosphoric acid. Lixiviation of treated materials with citric acid reagent shows that, after three days of reaction, losses in weight are considerable and the kinetic curves of phosphorus liberation present a linear evolution.The fertilizing value of these materials did not decrease during the leaching; so phosphorus will be solubilized with time thus allowing these materials to gain a good agronomical availability and to propose their use as delayed fertilizer types for tropical agricultural soils. 相似文献
52.
E.M.M. Ewais N.M. Khalil M.S. Amin Y.M.Z. Ahmed M.A. Barakat 《Ceramics International》2009,35(8):3381-3388
Four calcium aluminate cement mixes were manufactured from aluminum sludge as a source of calcium oxide and Al2O3 and aluminum slag (dross) as a source of aluminum oxide with some additions of pure alumina. The mixes were composed of 35–50% aluminum sludge, 37.50–48.75% aluminum slag (dross) and 12.50–16.25% aluminum oxide. The mixed were processed then sintered at different firing temperatures up to 1500 °C or 1550 °C. The mineralogical compositions of the fired mixes investigated using X-ray diffraction indicated that the fired mixes composed of variable contents of calcium aluminate (CA), calciumdialuminate (CA2), calciumhexaaluminate (CA6) in addition to some content of magnesium aluminate spinel (MA). Sintering parameters (bulk density, apparent porosity and linear change) and mechanical properties (cold crushing strength) of the fired briquettes were tested at different firing temperature. Refractoriness of the cement samples manufactured at the optimum firing temperature was detected. Cementing properties (water of consistency, setting time and compressive strength as a function of curing time up to 28 days of hydration) of pasted prepared from the manufactured cement mixes at the selected optimum firing temperatures (1400 °C or 1500 °C) were also tested. Cement mixes manufactured from 45 to 50% aluminum sludge, 37.50–41.25% aluminum slag (dross) with 12.50–13.75% alumina were selected as the optimum mixes for manufacturing calcium aluminate cement since they satisfy the requirements of the international standard specifications regarding cementing and refractory properties as a result of their content of CA (the main hydraulic phase in calcium aluminate cement) and CA2(the less hydraulic but more refractory phase). Although the recognized high refractoriness of CA6, its formation affect badly the cementing properties of the other non-optimum mixes. 相似文献
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54.
Emergence of Antibiotic Resistance in Listeria monocytogenes Isolated from Food Products: A Comprehensive Review 下载免费PDF全文
Amin N. Olaimat Murad A. Al‐Holy Hafiz M. Shahbaz Anas A. Al‐Nabulsi Mahmoud H. Abu Ghoush Tareq M. Osaili Mutamed M. Ayyash Richard A. Holley 《Comprehensive Reviews in Food Science and Food Safety》2018,17(5):1277-1292
Listeria monocytogenes is an opportunistic pathogen that has been involved in several deadly illness outbreaks. Future outbreaks may be more difficult to manage because of the emergence of antibiotic resistance among L. monocytogenes strains isolated from food products. The present review summarizes the available evidence on the emergence of antibiotic resistance among L. monocytogenes strains isolated from food products and the possible ways this resistance has developed. Furthermore, the resistance of food L. monocytogenes isolates to antibiotics currently used in the treatment of human listeriosis such as penicillin, ampicillin, tetracycline, and gentamicin, has been documented. Acquisition of movable genetic elements is considered the major mechanism of antibiotic resistance development in L. monocytogenes. Efflux pumps have also been linked with resistance of L. monocytogenes to some antibiotics including fluoroquinolones. Some L. monocytogenes strains isolated from food products are intrinsically resistant to several antibiotics. However, factors in food processing chains and environments (from farm to table) including extensive or sub‐inhibitory antibiotics use, horizontal gene transfer, exposure to environmental stresses, biofilm formation, and presence of persister cells play crucial roles in the development of antibiotic resistance by L. monocytogenes. 相似文献
55.
56.
Firouz FADAEIFARD Khamirul Amin MATORI Meysam TOOZANDEHJANI Abdul Razak DAUD Mohd Khairol Anuar Mohd ARIFFIN Norinsan Kamil OTHMAN Farhad GHARAVI Abdul Hadi RAMZANI Farhad OSTOVAN 《中国有色金属学会会刊》2014,24(4):1004-1011
采用场发射扫描电子显微镜(FE-SEM),研究转速对厚度为5 mm的6061-T6铝合金搅拌摩擦搭接焊接头的宏观和微观组织、硬度、搭接头剪切性能和失效模式的影响。结果表明:在最低的转速度下,上模板和下模板具有十分相似的硬度分布。采用EDX分析发现,焊核区的断裂面中含有Fe的化合物。 相似文献
57.
Chemical composition and antioxidant properties of Laurus nobilis L. and Myrtus communis L. essential oils from Morocco and evaluation of their antimicrobial activity acting alone or in combined processes for food preservation 总被引:1,自引:0,他引:1 下载免费PDF全文
58.
Barzegar Hassan Alizadeh Behbahani Behrooz Mehrnia Mohammad Amin 《Food science and biotechnology》2020,29(5):717-728
Food Science and Biotechnology - The instability and strong flavor or odor of essential oils (EO) limit their direct incorporation into food products. In this study, the antioxidant and... 相似文献
59.
A highly efficient solvent-free and simple one-pot approach for the synthesis of 4-hydroxythiazolidine-2-thione is described. The reaction of primary amines and carbon disulfide in the presence of 2-chloroacetaldehyde afforded the title compounds in high yields. 相似文献
60.
A planar antenna array that includes 12 corrugated tapered slot elements for use in ultrawideband (UWB) biomedical microwave imaging systems is presented. The used corrugate tapered slot antenna has a compact size, low profile, moderate gain, and distortionless performance in the time domain. The array is immersed in a carefully designed matching liquid of suitable dielectric constant to improve the matching between the array and the imaged object, and thus, to increase the dynamic range of the imaging system. A suitable platform is designed and fabricated to accommodate the array, breast phantom, and a coupling liquid for the case of UWB breast imaging. The design of the whole system is optimized using trust‐region framework method in the simulation tool CST Microwave Studio. The performance of the designed array is confirmed via measurements in a realistic imaging environment. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013. 相似文献