Did U.S. and Chinese investors respond differently to the exogenous shocks from COVID-19 and the war in Ukraine?

This paper investigates the U.S. and Chinese stock markets' long-run responses to COVID-19 and the Russia–Ukraine war, the main shocks that have recently battered the globalized economy. The investigation uses both static data analysis and ARMA-GARCH and DCC-GARCH dynamic risk models incorporating both events' impacts. Model fitting reveals opposite reactions of the two stock markets' long-run volatilities to the pandemic, but both volatilities have been enhanced by the war, with a much stronger reaction from the U.S. than from the Chinese market. Furthermore, the war has reduced the linkage between the two markets, while the pandemic has had no significant effect. The different responses of U.S. and Chinese investors may be attributed to the two countries' very different virus containment strategies, pandemic severities, and policy approaches to the geopolitical conflict. Our results have important practical implications for regulators' risk mitigation policy design and investors' cross-market hedging strategy development.

The impact of COVID-19 on the interdependence between US and Chinese oil futures markets

The oil futures market plays a vital role in the global financial system, especially after the negative future oil price rose during the COVID-19 pandemic. This paper investigates the COVID-19 impact on the interdependence between the US and Chinese oil futures markets by extending the dynamic conditional correlation-generalized autoregressive conditional heteroskedasticity (DCC-GARCH) models with incorporating COVID-19 variables and by applying vector autoregression (VAR) models. Our study reveals that the COVID-19 pandemic enhanced the long-run correlation between the two oil markets. In contrast, daily changes in pandemic severity had a negative effect on the short-term transient correlation. Our results show that COVID-19 changed the one-direction causality from the US oil market to the Chinese market in the pre-COVID period to a bidirectional causal relation between the two markets during the COVID period. It strengthened the volatility spillover effect from the Chinese to US markets. These findings are helpful to regulars' monitoring oil supply chain risk and investors' cross-market hedging of spillover risks from a systematic risk perspective.

Facial Synthesis and Bioevaluation of Well-Defined OEGylated Betulinic Acid-Cyclodextrin Conjugates for Inhibition of Influenza Infection.

Betulinic acid (BA) and its derivatives exhibit a variety of biological activities, especially their anti-HIV-1 activity, but generally have only modest inhibitory potency against influenza virus. The entry of influenza virus into host cells can be competitively inhibited by multivalent derivatives targeting hemagglutinin. In this study, a series of hexa-, hepta- and octavalent BA derivatives based on α-, ß- and γ-cyclodextrin scaffolds, respectively, with varying lengths of flexible oligo(ethylene glycol) linkers was designed and synthesized using a microwave-assisted copper-catalyzed 1,3-dipolar cycloaddition reaction. The generated BA-cyclodextrin conjugates were tested for their in vitro activity against influenza A/WSN/33 (H1N1) virus and cytotoxicity. Among the tested compounds, 58, 80 and 82 showed slight cytotoxicity to Madin-Darby canine kidney cells with viabilities ranging from 64 to 68% at a high concentration of 100 µM. Four conjugates 51 and 69-71 showed significant inhibitory effects on influenza infection with half maximal inhibitory concentration values of 5.20, 9.82, 7.48 and 7.59 µM, respectively. The structure-activity relationships of multivalent BA-cyclodextrin conjugates were discussed, highlighting that multivalent BA derivatives may be potential antiviral agents against influenza infection.

Progress of thrombus formation and research on the structure-activity relationship for antithrombotic drugs.

Many populations suffer from thrombotic disorders such as stroke, myocardial infarction, unstable angina and thromboembolic disease. Thrombus is one of the major threatening factors to human health and the prevalence of cardio-cerebrovascular diseases induced by thrombus is growing worldwide, even some persons got rare and severe blood clots after receiving the AstraZeneca COVID vaccine unexpectedly. In terms of mechanism of thrombosis, antithrombotic drugs have been divided into three categories including anticoagulants, platelet inhibitors and fibrinolytics. Nowadays, a large number of new compounds possessing antithrombotic activities are emerging in an effort to remove the inevitable drawbacks of previously approved drugs such as the high risk of bleeding, a slow onset of action and a narrow therapeutic window. In this review, we describe the causes and mechanisms of thrombus formation firstly, and then summarize these reported active compounds as potential antithrombotic candidates based on their respective mechanism, hoping to promote the development of more effective bioactive molecules for treating thrombotic disorders.

COVID-19 impact on commodity futures volatilities.

COVID-19 pandemic has affected almost all aspects of the global economy, especially commodity futures markets, due to the disruption risk of global supply chains from the pandemic lockdown. This paper extends ARMA-GARCH models to investigate the pandemic impact on both long-run and short-term volatilities of four major commodity futures. Model-fitting results reveal that the pandemic event has enhanced long-run volatilities for all futures returns, while the daily COVID-19 infection speed has mixed effects on short-term (instantaneous) volatilities. Our extended models and research findings are useful in global supply chain risk management, commodity options trading and regulators' supervision of inflation risk.