ABSTRACT
The stress-strain constitutive model under uniaxial compression is a basic element and important characterization method for determining physical and mechanical properties in cement-based materials research. In this study, a stress-strain constitutive model under uniaxial compression was established, which was based on a new nano-stabilized soil (NSS) through typical mechanical tests and constitutive relationship research. The results indicate that the unconfined compressive strength (UCS) of the nano-stabilized soil was enhanced with the increase in curing period and nano-stabilizer dosage, and that the strength growth rate reaches the maximum at a 12% dosage in the tested samples. The UCS of NSS under a 12% dosage is about 10~15% higher than that of ordinary stabilized soil (SS) without nano doping, and 25~40% higher compared with grade 42.5 cement-soil. The established constitutive model could accurately describe the linear-elastic and elastic-plastic deformation characteristics of NSS under uniaxial compression, which will be conducive to revealing the curve variation law of the stress-strain process. The research results could provide scientific support for the theoretical innovation and engineering application of green environmental protection materials.
ABSTRACT
This paper uses a time-varying Granger causality test and time-varying parameter vector autoregression with stochastic volatility model to analyze the effects of infectious disease equity market volatility (ID-EMV), geopolitical risk (GPR), and speculation on commodity returns. The time-varying effects of ID-EMV, GPR, and speculation on commodity returns are investigated and compared in five epidemics during 1998-2021: Bird Flu in 1998, SARS in 2003, Swine Flu in 2009, MERS and Ebola in 2014, and COVID-19 in 2019. A further analysis is performed for five commodity subcategories of textiles, industry, metals, livestock, and food. Results show that time-varying effects are significant, and most responses to ID-EMV are positive, to GPR are changing from negative to positive, and to speculation are negative. Notably, ID-EMV in the ongoing COVID-19 pandemic is the worst hit to commodity returns in more than two decades.
ABSTRACT
We report the design and synthesis of a new class of fluorogenic probes based on monoamine oxidase-triggered oxidative C-O bond cleavage. The selectivity of probe P1 towards MAO-B was 22-fold higher than that towards MAO-A.
