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排序方式: 共有1313条查询结果,搜索用时 218 毫秒
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Hugo Uvegi Piyush Chaunsali Brian Traynor Elsa Olivetti 《Journal of the American Ceramic Society》2019,102(12):7678-7688
An untapped source of amorphous SiO2, industrially generated Indian biomass ash (SA)—90% amorphous, with composition of ~60% SiO2 and ~20% unburnt carbon—can be used to produce cementitious and alkali-activated binders. This study reports dissolution of amorphous Si from SA in 0.5 mol/L and 1 mol/L aqueous NaOH, with and without added Ca(OH)2, at SA:Ca(OH)2 wt% ratios of 100:0, 87.5:12.5, and 82.5:17.5. Monitoring of elemental dissolution and subsequent/simultaneous product uptake by ICP-OES offers an effective process for evaluating utility of industrial wastes in binder-based systems. After 28 days in solution, up to 68% of total Si is dissolved from SA in 1 mol/L NaOH, with values as much as 38% lower in the presence of Ca(OH)2, due to the formation of tobermorite-like C-S-H. FTIR, 29Si MAS-NMR, and XRD are used to characterize solid reaction products and observe reaction progress. Product chemistries calculated from ICP-OES results and verified by selective dissolution in EDTA/NaOH—namely, Ca/Si of 0.6-1 and Na adsorption of 1-2 mmol/g—are found to be consistent with those indicated by aforementioned techniques. This indicates the efficacy of ICP-OES in estimating product chemistry via such a methodology. 相似文献
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In this work, the interdiffusion between a MCrAlY-bond coat and two different nickel-based superalloys is evaluated at three temperatures, 950 °C, 980 °C, and 1,050 °C. Of primary interest is the evolution of Kirkendall-porosity, the β-depleted zone in the bond coat and the β’- depleted zone in the superalloy. The three phenomena arise near the interface between bond coat and superalloy as a result of interdiffusion between both materials and are detrimental to the coating-substrate system. The evolution of the interdiffusion phenomena is highly dependent on the alloy composition of the materials as well as the annealing temperature. It has been found that not only the temperature dependency of the diffusion coefficient but also the temperature dependent element activities are an important factor when evaluating the interdiffusion phenomena. It has further been shown that at lower temperatures the amount of Kirkendall-porosity per volume fraction is higher than at higher temperatures, even though the overall amount of porosity is lower. Different equilibrium concentrations of main alloying elements and a correspondingly lower over-saturation of vacancies have been identified as the main explanation. 相似文献
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Tim Winter 《The Journal of Architecture》2016,21(3):418-432
Within the debate about fostering more sustainable built environments one of the key battlegrounds surrounds thermal comfort, and in particular the use of air conditioning. In the search for less energy-intensive alternatives, a renewed interest has emerged around the design vocabulary of ‘passive cooling’. The paper argues that the terminology of passive/active needs inverting for such approaches to gain wider support as a viable alternative to mechanical cooling.
It is argued that non-air-conditioned buildings actively engage with their environments and that the current notion of passive cooling leaves us blind to the ways occupants, buildings and the material culture of interior spaces are all entangled in relations that enable thermal comfort to be actively achieved and maintained. To present this argument for re-categorising low-carbon architecture design as active cooling, the paper draws on the concept of entanglement. 相似文献
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Wong Ademar Materón Elsa María Freitas Tayane A. Faria Ronaldo C. Gonçalves Débora Del Pilar Taboada Sotomayor Maria 《Journal of Applied Electrochemistry》2022,52(8):1249-1257
Journal of Applied Electrochemistry - The present work reports the development of screen-printed electrode (SPE) using flexible polyester sheets modified with nanodiamond (ND), Au nanoparticles... 相似文献
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目前世界上普遍应用的配电系统消弧线圈接地方式在一定程度上保证了系统的供电可靠性,但仍然存在接地残流较大和高阻型故障检测难等问题。GFN(接地故障全中和器)具有消除接地电流、准确定位故障点,以及提升供电稳定性和可靠性的作用。介绍了瑞典GFN接地故障全补偿技术的基本原理、功能特点、应用实例和功能扩展等。实用情况表明GFN接地故障全补偿技术可以较为成功地减少特殊瞬时故障。 相似文献
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Comparison of 10,11‐Dehydrocurvularin Polyketide Synthases from Alternaria cinerariae and Aspergillus terreus Highlights Key Structural Motifs 下载免费PDF全文
Rachel V. K. Cochrane Dr. Zhizeng Gao Gareth R. Lambkin Dr. Wei Xu Prof. Jaclyn M. Winter Sandra L. Marcus Prof. Yi Tang Prof. John C. Vederas 《Chembiochem : a European journal of chemical biology》2015,16(17):2479-2483
Iterative type I polyketide synthases (PKSs) from fungi are multifunctional enzymes that use their active sites repeatedly in a highly ordered sequence to assemble complex natural products. A phytotoxic macrolide with anticancer properties, 10,11‐dehydrocurvularin (DHC), is produced by cooperation of a highly reducing (HR) iterative PKS and a non‐reducing (NR) iterative PKS. We have identified the DHC gene cluster in Alternaria cinerariae, heterologously expressed the active HR PKS (Dhc3) and NR PKS (Dhc5) in yeast, and compared them to corresponding proteins that make DHC in Aspergillus terreus. Phylogenetic analysis and homology modeling of these enzymes identified variable surfaces and conserved motifs that are implicated in product formation. 相似文献
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Gustavo Da Silva Rita Serrano Elsa Teixeira Gomes Olga Silva 《Microscopy research and technique》2015,78(11):1001-1009
Gymnosporia arenicola Jordaan (Celastraceae) is a shrub or small tree, which naturally occurs in coastal sand dunes of Southern Mozambique and South Africa. Its dried leaf is often used in traditional medicine for the treatment of infectious and inflammatory diseases. Hereby, we present results of studies carried out according to the pharmacopoeia standards for the identification of herbal drugs, in the whole, fragmented, and powdered plant material. These results were complemented with scanning electron microscopy and histochemical techniques. The leaf microscopic analysis revealed a typical dorsiventral mesophyll with a corresponding spongy parenchyma–palisade parenchyma ratio of 0.60, anomocytic and paracytic stomata, papillate cells with a diameter of 4.00 ± 0.40 µm, multicellular uniseriate nonglandular trichomes with a length of 27.00 ± 4.10 µm and cristalliferous idioblasts containing calcium oxalate cluster crystals with a diameter of 23.04 ± 5.84 µm. The present findings demonstrate that the G. arenicola leaf has both nonglandular trichomes and hypoderm, features not previously described in the corresponding botanical section (Gymnosporia sect. Buxifoliae Jordaan). The establishment of these new botanical markers for the identification of G. arenicola leaf is essential for quality, safety and efficacy reasons. Microsc. Res. Tech. 78:1001–1009, 2015. © 2015 Wiley Periodicals, Inc. 相似文献