474 research outputs found
Mechanism of microstructural modification of the interfacial transition zone by using blended materials
Applying blended materials with finer particle size or high reactivity could be an effective and economic way for improving the microsturcture of interfacial transition zone (ITZ). In this study, the porosity characteristics of ITZ in concrete made with OPC and blended binders were determined quantitatively by using backscattered electron microscopy (BSE) image analysis and mercury intrusion porosimetry (MIP) measurements. This paper especially focused on the effects of slag and limestone filler on the thickness and pore structure of the ITZ. Results indicated that the porosity at each distance reduces with increasing limestone filler from 0 to 5%, and a significant increase is observed in the sample with 10% of limestone filler. The addition of 5% of limestone filler is able to densify the pore structure of both ITZ and bulk matrix. The reduction in pore volume in the range coarser than 100 nm contributed to the largest decrease in the total pores. Increasing the incorporation level of limestone filler to 10% resulted in an increase in the total porosity. The influences of slag on the porosity characteristics were highly dependent on the replacement level and the determined pore size regions. The addition of 35% of slag reduces the porosity at all distances and produces a denser microstructure both in the ITZ and bulk cement matrix. However, this improvement disappears when the substitution amount reaches to 70%. The incorporation of slag as a partial substitute for Portland cement tends to refine the pore structure
Investigation of the deterioration of blended cement concrete under sulfate attack in terms of interfacial transition zone
The importance of the porous interfacial transition zone to the chemical aggression of
concrete is obvious when one considers the relations existing between porosity, permeability, chemical
composition and the sulfate attack. In this study, the effect of ITZ quantity through varying aggregate
content on the deterioration of blended cement concrete under sulfate attack, was determined to
understand better the relationship between sulfate ions and concrete microstructure. The ITZ quantity
was directly proportional to the aggregate volume fraction. Therefore, the effect of ITZ on sulfate
resistance ability of concrete made with pure OPC and blended binders was evaluated by a comparison
among mortars with systematically varied aggregate volume fraction. The porosity distribution with the
ITZ was determined by using a quantitative backscattered electron microscopy (BSE) image analysis. It
was found that the incorporation of moderate amount of Limestone filler is able to compact the
microstructure of both ITZ and bulk matrix by filling effect and nucleation sites effect. The effects of
slag on the porosity of ITZ were dependent on the replacement rate. The degree of deterioration had a
slight tendency to increase for the samples prepared with higher aggregate volume content, which
means high ITZ volume fraction. For the sulfate to reach the interior of the samples, it must move
through the bulk cement matrix. The effect of aggregate and ITZ can only be notable when the interior
structure was exposed to the sulfate ions. The presence of ITZ was normally accompanied by a denser
bulk cement matrix. This could limit the ingress of sulfate ions and delay the formation of expansive
products in initial stage. After the sulfate penetrates into the interior of the samples, the inner structure
was expected to exert more significant influences on the deterioration
Characterization of ITZ in ternary blended cementitious composites: experiment and simulation
The preparation, characterization, and pharmacokinetic studies of chitosan nanoparticles loaded with paclitaxel/dimethyl-β-cyclodextrin inclusion complexes
7-Methoxy-3-(4-methoxyphenyl)chroman-4-one
The asymmetric unit of the title compound, C17H16O4, contains two crystallographically independent molecules with different absolute configurations
On-chip black hole: Hawking radiation and curved spacetime in a superconducting quantum circuit with tunable couplers
Hawking radiation is one of quantum features of a black hole, which can be
understood as a quantum tunneling across the event horizon of the black hole,
but it is quite difficult to directly observe the Hawking radiation of an
astrophysical black hole. Remarkable experiments of analogue black holes on
various platforms have been performed. However, Hawking radiation and its
quantum nature such as entanglement have not been well tested due to the
experimental challenges in accurately constructing curved spacetime and
precisely measuring the thermal spectrum. Based on the recent architecture
breakthrough of tunable couplers for superconducting processor, we realize
experimentally an analogue black hole using our new developed chip with a chain
of 10 superconducting transmon qubits with interactions mediated by 9
transmon-type tunable couplers. By developing efficient techniques to engineer
the couplings between qubits via tuning couplers, we realize both the flat and
curved spacetime backgrounds. The quantum walks of quasi-particle in the curved
spacetime reflect the gravitational effect around the black hole, resulting in
the behavior of Hawking radiation. By virtue of the state tomography
measurement of all 7 qubits outside the analogue event horizon, we show that
Hawking radiation can be verified. In addition, an entangled pair is prepared
inside the horizon and the dynamics of entanglement in the curved spacetime is
directly measured. Our results would stimulate more interests to explore
information paradox, entropy and other related features of black holes using
programmable superconducting processor with tunable couplers.Comment: modified manuscripts, 7 pages, 4 figures (main text) + 12 pages
(supplementary information
Research on the Removal Effect and Mechanism of Tibet Rhodotorula mucilaginosa on Zearalenone
In order to explore an environmental removal method of grain mycotoxins and to overcome the problem of poor stability of biodegradation method, the Tibetan yeast strains were selected as the research object, and the strains with better degradation effects on zearalenone (ZEN) were screened to explore the functions and mechanisms in this study.The results showed that Tibet Rhodotorula mucilaginosa had a good degradation effect on ZEN, and the degradation effect gradually improved with the increase of the bacterial concentration.Through the evaluation of the toxin removal effect of different yeast treatment solutions, it was found that the removal mechanism of the yeast on ZEN was mainly adsorption, accompanied by a certain degree of intracellular biodegradation.The degradation products of ZEN were determined by liquid chromatography-mass spectrometry.It was found that the degradation products may be zearalenol and zearalenone, and the safety of the degradation products needed further verification.The stress tolerance test of Tibet R.mucilaginosa showed that it had a certain tolerance to low temperature and oxidative stress
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