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1.
《Advanced Powder Technology》2020,31(12):4585-4597
Focussing on visible light active ferrites for high performance removal of noxious pollutants, we report the synthesis of Mg0.5NixZn0.5-xFe2O4 (x = 0.1, 0.2, 0.3, 0.4, & 0.5) ferrite nanoparticle for degradation of reactive blue-19 (RB-19). Lattice parameters calculated using intense X-ray diffraction (XRD) peaks and Nelson-Riley plots (N-R plot) are in well agreement with each other. The sample Mg0.5Ni0.4Zn0.1Fe2O4 (M5N4) exhibits best performance with 99.5% RB-19 degradation in 90 min under visible light. Photoluminescence (PL) results confirm that recombination of charge carriers is highly reduced in the photocatalyst. Scavenging experiments suggest that O2− radicals were the dominant species responsible for photocatalytic performance. The photocatalytic mechanism was explained in terms of dopant driven shifting of conduction bands and valence bands (calculated by Mott-Schottky plots). The thermodynamic probability of radical generation along with role of redox cycles of metal ions has been discussed in the mechanism. The dye degradation was ascertained by detection of intermediates via mass spectrometry analysis and a possible degradation route was also predicted. The findings in this work provide intriguing opportunities to modify the electronic band structure of spinel ferrites for visible and solar light photocatalytic activity for environmental detoxification. 相似文献
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土木工程施工课程作为土木工程及工程管理专业的学科基础课和核心专业课程,在疫情防控期间"停课不停教""停课不停学"的要求下,通过线上平台进行授课。由于土木工程施工课程内容庞杂、综合性强、实践性强,且章节之间关联性较弱,探究既能使学生快速适应,又能保证教学质量的在线教学方法至关重要。以华南某高校土木工程施工课程为例,基于中国大学MOOC、建筑云课、腾讯课堂、QQ群等线上平台讲授教学内容,并运用问卷调查对课程线上教学效果进行评价。结果表明,线上教学为学生提供了丰富灵活的学习方式,显著提高了学生的自主学习能力,扩大了学生的知识面,达到了较好的学习效果。 相似文献
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《Food Control》2006,17(2):108-113
The concept of food safety has lately acquired a new approach due to globalization and free trade in food. Introducing a HACCP system in the production and trade in food has become a necessity. The term “food trade” indicates all the postproduction procedures, from storage, transport and distribution to retail, including export and import. The aim of our 2002 survey was to analyse the situation of cold chain maintaining in food trade in Ljubljana, the capital of Slovenia. The research was based upon two hypotheses: in the first one we supposed that a cold chain is interrupted in retail and in the second one we supposed that the handling of food in retail varies. Seventeen stores were divided in three groups, according to sales area of the store: large ones, medium ones and small ones. Temperature conditions in cooling appliances for storage of 1688 perishable food products were measured. Products were inspected by two criteria, by the “best before” date and by the storage temperature. The results confirmed both of the hypotheses. The storage conditions were properly labelled on the packages of the products inspected. In most of the cases the temperatures measured differed from the required ones, even for up to 10 °C. The biggest differences were detected between temperatures indicated on cooling appliances and temperatures measured by our calibrated thermometers. Conditions during food storage and in retail stores were not documented and there was no system to control the cold chain. Our findings have shown that retailers are not familiar with the importance of maintaining a cold chain. The result of that can be a shorter durability of highly perishable foodstuffs and their safety for consumers is questionable. 相似文献
4.
《Sensors and actuators. A, Physical》2006,125(2):223-233
To characterize the thickness of a corrosive fluid system's coated facilities, such as pipes, tubes, tanks, and structural members, a complex ultrasonic transducer capable of measuring multilayered parts was fabricated and the time and frequency responses were evaluated. The target transducer was constructed with two active dual elements made from tape-cast PbNb2O6 sheets and an additional thin-film active element made from sol–gel spin-coated Pb(Zr0.52Ti0.48)O3 films. After adjusting the properties of each active element, a complex transducer was assembled after matching the impedance of each element and considering the minimal interference between the active layers. The impulse response of the assembled complex transducer shows excellent characteristics. Moreover, the assembled transducer's capability of accurately measuring the thickness assures that it can be directly applied to related industries. 相似文献
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Novel lamellar mesostructured hydroxyapatites have firstly been synthesized by template-assisted technique. The mild and nontoxic surfactant, phosphoric acid monododecyl ester (MAP), is used to act as a structure-directing template. The structure of sample was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscope and Transmission electron microscopy. The results indicate that the obtained sample is a well-organized lamellar mesostructured hydroxyapatite with a uniform layer spacing of 3.64 nm. 相似文献
7.
《Journal of the European Ceramic Society》2005,25(2-3):129-135
A poly(aminoborazine), precursor for hexagonal boron nitride (h-BN) obtained by reaction of borazine B3N3H6 with ammonia, and its pyrolysis derivatives have been extensively characterised by 15N and 11B MAS NMR. The various B and N sites have been identified according to their first neighbouring atoms, as well as to the second ones in the case of 15N, and have also been quantified. This study demonstrates that a suitable choice of NMR techniques together with the use of isotopic enrichment can lead to a large improvement in spectral resolution, which allows a better understanding of such complex BN preceramic polymer structures and permits to follow the polymer-to-ceramic transformation. 相似文献
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Microstructure evolution of AZ31 magnesium alloy during equal channel angular extrusion 总被引:3,自引:0,他引:3
Li Yuanyuan Zhang Datong Chen Weiping Liu Ying Guo Guowen 《Journal of Materials Science》2004,39(11):3759-3761