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排序方式: 共有1362条查询结果,搜索用时 15 毫秒
1.
Gabriel Falzone Iman Mehdipour Narayanan Neithalath Mathieu Bauchy Dante Simonetti Gaurav Sant 《American Institute of Chemical Engineers》2021,67(5):e17160
Portlandite (Ca(OH)2; also known as calcium hydroxide or hydrated lime), an archetypal alkaline solid, interacts with carbon dioxide (CO2) via a classic acid–base “carbonation” reaction to produce a salt (calcium carbonate: CaCO3) that functions as a low-carbon cementation agent, and water. Herein, we revisit the effects of reaction temperature, relative humidity (RH), and CO2 concentration on the carbonation of portlandite in the form of finely divided particulates and compacted monoliths. Special focus is paid to uncover the influences of the moisture state (i.e., the presence of adsorbed and/or liquid water), moisture content and the surface area-to-volume ratio (sa/v, mm−1) of reactants on the extent of carbonation. In general, increasing RH more significantly impacts the rate and thermodynamics of carbonation reactions, leading to high(er) conversion regardless of prior exposure history. This mitigated the effects (if any) of allegedly denser, less porous carbonate surface layers formed at lower RH. In monolithic compacts, microstructural (i.e., mass-transfer) constraints particularly hindered the progress of carbonation due to pore blocking by liquid water in compacts with limited surface area to volume ratios. These mechanistic insights into portlandite's carbonation inform processing routes for the production of cementation agents that seek to utilize CO2 borne in dilute (≤30 mol%) post-combustion flue gas streams. 相似文献
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Chun Fah Mok Yern Chee Ching Noor Azuan Abu Osman Farina Muhamad Mohd Usman Mohd Junaidi Jia H. Choo 《应用聚合物科学杂志》2020,137(35):49044
In the quest on improving composite formulations for environmental sustainability, maleic acid (MA) cross-linked poly(vinyl alcohol) (PVA)-α-chitin composites reinforced by oil palm empty fruit bunch fibers (OPEFB)-derived nanocellulose crystals (NCC) had been successfully prepared. Based on the Fourier transform infrared (FTIR) spectroscopic analysis, it was proven that molecular interactions of the cross-linker to the polymeric networks was through conjugated ester linkage. Differential scanning calorimetry (DSC) showed that the influence of MA was minimal toward crystallization in the PVA/chitin/NCC composite. Maximum tensile strength, elongation at break and Young's modulus of the respective PVA/chitin/NCC composites were achieved at different content of MA, dependent on the PVA/chitin mass ratio. Among all compositions, a maximum Young's modulus was achieved at 30 wt% MA loading in PVA/chitin-30/NCC, amounting to 2,413.81 ± 167.36 MPa. Moreover, the mechanical properties and selected physicochemical properties (swelling, gel content, and contact angle) of the PVA/chitin/NCC composites could be tailored by varying the chitin content (10–30 wt%) and MA content (10–50 wt% based on total mass of composite). In brief, this chemically cross-linked PVA-based biocomposites formulated with sustainable resources exhibited tunable physicochemical and mechanical properties. 相似文献
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There exist only a few papers in the literature which target the problem of “proposing a secure designated server identity-based encryption with keyword search scheme.” In this paper, we prove that they all suffer from security issues, and therefore, this challenging problem still remains open. 相似文献
5.
Mohammad Maleki Shahraki Mohammad Golmohammad Iman Safaee Mehdi Delshad Chermahini 《Ceramics International》2018,44(3):3388-3393
In this research, the addition effects of three different quantities of micron-sized seeds (microseeds) to a SnO2 varistor prepared from nanomaterials on the microstructure and electrical properties were studied. Moreover, surge-withstanding capability of low-voltage SnO2 varistors was investigated. The X-ray diffraction pattern disclosed a single phase SnO2 for microseed grains. The morphological features of samples were characterized using scanning electron microscopy. The abnormal distribution of grain size with elongated grains of SnO2 in fine grains matrix was observed in sintered samples without microseeds. The low content of microseed addition (0.3 wt%) had not controlled abnormal grain growth, however, it increased mean grain size to 37 µm. Although the high content of microseeds (7.5 wt%) stopped abnormal grain growth, it had a negative effect on relative density and mean grain size. The normal grain size distribution with maximum mean grain size (45 µm) was obtained in samples containing 1.5 wt% microseeds. These samples showed the lowest breakdown field (240 V/cm) and the highest surge-withstanding capability (1.5 kA/cm2). Furthermore, the standard deviation of the electrical parameters of these samples was improved due to normal grain-size distribution. 相似文献
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Silicon - Silica nanoparticles (SiO2-NPs), modified silica nanoparticles with cysteine (SiO2-Cys) or methionine (SiO2-Meth) were used for sorption of uranium (VI) ion from aqueous solution. Silica... 相似文献
8.
Dr. Liam J. Stephens Dr. Aviva Levina Dr. Iman Trinh Dr. Victoria L. Blair Dr. Melissa V. Werrett Prof. Peter A. Lay Prof. Philip C. Andrews 《Chembiochem : a European journal of chemical biology》2020,21(8):1188-1200
RuII-arene complexes provide a versatile scaffold for novel anticancer drugs. Seven new RuII-arene-thiocarboxylato dimers were synthesized and characterized. Three of the complexes ( 2 a , b and 5 ) showed promising antiproliferative activities in MDA-MB-231 (human invasive breast cancer) cells, and were further tested in a panel of fifteen cancerous and noncancerous cell lines. Complex 5 showed moderate but remarkably selective activity in MDA-MB-231 cells (IC50=39±4 μm Ru). Real-time proliferation studies showed that 5 induced apoptosis in MDA-MB-231 cells but had no effect in A549 (human lung cancer, epithelial) cells. By contrast, 2 a and b showed moderate antiproliferative activity, but no apoptosis, in either cell line. Selective cytotoxicity of 5 in aggressive, mesenchymal-like MDA-MB-231 cells over many common epithelial cancer cell lines (including noninvasive breast cancer MCF-7) makes it an attractive lead compound for the development of specifically antimetastatic Ru complexes with low systemic toxicity. 相似文献
9.
Zohre Ahmadi Behzad Nayebi Mehdi Shahedi Asl Iman Farahbakhsh Zohre Balak 《Ceramics International》2018,44(10):11431-11437
Taguchi design of experiments methodology was used to determine the most influential spark plasma sintering (SPS) parameters on densification of TiB2–SiC ceramic composites. In this case, four processing factors (SPS temperature, soaking time, applied external pressure and SiC particle size) at three levels were examined in order to acquire the optimum conditions. The statistical analysis identified the sintering temperature as the most effective factor influencing the relative density of TiB2–SiC ceramics. A relative density of 99.5% was achieved at the optimal SPS conditions; i.e. temperature of 1800?°C, soaking time of 15?min and pressure of 30?MPa by adding 200-nm SiC particulates to the TiB2 matrix. The experimental measurements and predicted values for the relative density of composite fabricated at the optimum SPS conditions and reinforced with the proper SiC particle size were almost similar. The mechanisms of sintering and densification of spark plasma sintered TiB2–SiC composites were discussed in details. 相似文献
10.
Telecommunication Systems - In the era of Internet-of-things (IoT), the future 5G networks are supposed to provide ubiquitous connectivity, high speed, as well as low latency and energy efficiency... 相似文献