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Mechanical and Durability Properties of Cementless Concretes Made Using Three Types of CaO-Activated GGBFS Binders
Get PDFThis study examined the mechanical and durability properties of CaO-activated ground-granulated blast-furnace slag (GGBFS) concretes made with three different additives (CaCl2, Ca(HCOO)(2), and Ca(NO3)(2)) and compared their properties to the concrete made with 100% Ordinary Portland Cement (OPC). All concrete mixtures satisfied targeted air content and slump ranges but exhibited significantly different mechanical and durability properties. The CaO-activated GGBFS concretes showed different strength levels, depending on the type of additive. The added CaCl2 was the most effective, but Ca(NO3)(2) was the least effective at increasing mechanical strength in the CaO-activated GGBFS system. The OPC concrete showed the most excellent freezing-thawing resistance in the durability test, but only the CaO-activated GGBFS concrete with CaCl2 exhibited relatively similar resistance. In addition, the chemical resistance was significantly dependent on the type of acid solution and the type of binder. The OPC concrete had the best resistance in the HCl solution, while all CaO-activated GGBFS concretes had relatively low resistances. However, in the H2SO4 solution, all CaO-activated GGBFS concretes had better resistance than the OPC concrete. All concrete with sulfate ions had ettringite before immersion. However, when they were immersed in HCl solution, ettringite tended to decrease, and gypsum was generated. Meanwhile, the CaO-activated GGBFS concrete with CaCl2 did not change the type of reaction product, possibly due to the absence of ettringite and Ca(OH)(2). When immersed in an H2SO4 solution, ettringite decreased, and gypsum increased in all concrete. In addition, the CaO-activated concrete with CaCl2 had a considerable amount of gypsum; it seemed that the dissolved C-S-H and calcite, due to the low pH, likely produced Ca2+ ions, and gypsum formed from the reaction between Ca2+ and H2SO4
Diversification of the Cold War History: New Approaches and Dilemmas
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Crafting Distrust of the Media in the Pathology of Public Discourses and the Politics of Public Opinion Polls
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Differential modulation of behavior by infraslow activities of different brain regions
Get PDFThe oscillation phase of electroencephalograms (EEGs) is associated with behavioral performance. Several studies have demonstrated this association for relatively fast oscillations (>1 Hz); a similar finding has also been reported for slower oscillations, showing that behavioral performance is correlated with the phase of infraslow activity (ISA, 0.01???0.1 Hz) of electroencephalography (EEG). However, the previous study only investigated ISA in a local brain region using a relatively simple task (somatosensory discrimination task), leaving it difficult to determine how the EEG ISA for various brain regions is associated with behavioral performance. In addition, it is not known whether the EEG ISA phase modulates more complex behavioral task performance. In the present study, we analyzed the ISA of whole-brain EEG of participants performing various behaviors while playing video games. We found that behavior was associated with the specific oscillation phase of EEG ISA when that behavior was independent of other behaviors. In addition, we found that the EEG ISA oscillation phases modulating the different behaviors varied across brain regions. Our results suggest that the EEG ISA for different brain regions modulates behavioral performance in different ways and such modulation of EEG ISA can be generalized to diverse behaviors. This study may deepen the understanding of how EEG ISA modulates behavior and increases the applicability of EEG ISA
Strong interfacial energetics between catalysts and current collectors in aqueous sodium-air batteries
No full textConventional binders, such as polyvinylidene fluoride, are not ideal candidates for aqueous sodium???air batteries (SABs) because of their relatively low adhesiveness, weak mechanical strength, and inherent hydrophobicity. The low adhesion strength often leads to electrocatalysts and carbon current collector detachments, followed by degradation of electrochemical performance over time. For SABs to possess excellent performance, development of advanced polymeric binders with high wettability and underwater adhesion is required. In this study, the adhesion stability of the electrocatalyst/current collector interface is significantly enhanced by using synthesized catechol-derivative hydrophilic binders, whereas catalyst desorption and carbon corrosion are effectively prevented. Using high-resolution transmission electron microscopy, we demonstrated the role of synthesized binders on the morphological stability of the composite electrode. Furthermore, surface forces apparatus and density functional theory calculations reveal insights into how polymeric binders impact the adhesion mechanism and battery performance of SAB based on their functional groups
Proton branching ratios of Mg-23 levels
No full textBackground: The anomalous Ne-22 abundance measured in certain presolar graphite grains is thought to arise from the decay of Na-22 that was synthesized at high temperatures in core-collapse supernovas. To better interpret this abundance anomaly, the primary destruction mechanism of Na-22, the Na-22(p, gamma)Mg-23 reaction, must be better understood. Purpose: Determine proton branching ratios of several Mg-23 excited states that play a role in the hightemperature Na-22(p, gamma)Mg-23 reaction rate. Methods: Particle decays of Mg-23 excited states populated with the previously reported Mg-24(p, d)Mg-23 transfer reaction measurement [Kwag et al., Fur. Phys. J. A 56. 108 (2020)] were analyzed to extract proton branching ratios. The reaction was studied using a 31-MeV proton beam from the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory and Mg-24 solid targets. Results: Proton branching ratios of several Mg-23 excited states in the energy range E-x = 8.044-9.642 MeV were experimentally determined for the first time for the p0 and p1' (p1 + p2 + p3) decay channels. Conclusions: These new branching ratios for Mg-23 levels can provide an experimental foundation for an improved high-temperature rate of the Na-22(p, gamma)Mg-23 reaction needed to understand production of anomalously high Ne-22 abundance in core-collapse supernovas
Mitigating Jahn???Teller Effects by Fast Electrode Kinetics Inducing Charge Redistribution
No full textManganese hexacyanomanganates have attracted significant attention as promising cathode materials for sodium-ion batteries owing to the high theoretical capacity and low cost of Mn resources. Because of the strong Jahn???Teller effect, causing unstable local phase transition and distortion, the redox reactions of the high-spin state of Mn(III) are considered to be a conundrum. Herein, it is reported that the charge-redistribution mechanism of low-spin M
Machine Learning-Based Seismic Assessment of Steel Moment Frames
No full textDepartment of Urban and Environmental Engineering (Disaster Management Engineering)clos
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No full textSchool of Energy and Chemical Engineering (Energy Engineering)clos
Individually Adrressable Pixel Driver Circuit for an Active Matrirx Micro-LED Automotive Headlamp
No full textDepartment of Electrical EngineeringThis thesis presents individually addressable pixel driver circuit for a digitized automotive headlamp. This pixel driver is a key component of an active-matrix array that is driven by row and column drivers. It contains a 11-bit memory cell and a combination logic circuitry in order to generate a string of PWM (Pulse Width Modulation) pulse for dimming, so that it can drive the LED connected to the pixel driver by using a constant current source. The thesis also proposes a current driver focusing on the flexibility of array size, stable driving current with low static power dissipation. The pixel driver is designed and fabricated on a 180nm CMOS process and verified in array structure by using a FPGA signal source.ope