Return and volatility connectedness of the non-fungible tokens segments

Non-fungible tokens (NFTs) have garnered attention from investors and the general public. This pioneering study analyzes the connectedness of five NFT segments by employing the TVP-VAR based connectedness approach of Antonakakis et al. (2020) to identify the transmitter and receivers of spillover for both return and volatility of NFT segments. Our results show that Utility NFTs are the main transmitter of spillover, whereas the collectible NFTs are the main recipient of spillover for both return and volatility. Our findings have important implications for both investors and policy makers. (c) 2022 Elsevier B.V. All rights reserved.

IN SILICO IDENTIFICATION OF A VIRAL SURFACE GLYCOPROTE IN SITE SUITABLE FOR THE DEVELOPMENT OF LOW MOLECULAR MASS INHIBITORS FOR VARIOUS VARIANTS OF SARS-COV-2

Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) is a new coronavirus today has an extremely significant impact on both the global economy and society as a whole, due to its pandemic status and risk of complica-tions. Therefore, understanding the molecular features of the interaction of receptor binding domain (RBD), which determines most of the dangerous properties of this pathogen, with human angiotensin-converting enzyme 2 (hACE2) is an important step in the process of developing a successful strategy to combat SARS-CoV-2. In addition, given the significant rate of accumulation of mutations in RBD, it makes sense to consider its different variants. Goal. Identification of a pocket potentially suitable for the search for low molecular mass inhibitors of the interaction of different variants of SARS-CoV-2 RBD and hACE2. Methods. The initial structure of different variants of the RBD/hACE2 complex was obtained from Protein Data Bank (PDB). Separate RBD variants were isolated from the same data. To obtain the Y453F mutant, variant P.1 was mutagenized in PyMol 1.8. The construction of the system, which included the resulting associ-ate or individual protein, solvent, and physiological concentration of sodium chloride, was performed using CHARMM-GUI (graphical user interface for CHARMM) tools according to the standard protocol for glycoproteins. The actual simulation and balancing of the system were performed in GROMACS (GROningen MAchine for Chemical Simulation) version 2019.6 for 50 ns. Results. The interface of the RBD/hACE2 interaction is formed by amino acids Q24, D30, H34, E35, E37, Y41, Y83, K353, D355, and R393 for hACE2 and K417, Y453, F486, N487, Y489, Q493, Q498, T500, N501, and Y505 — for RBD. However, it is heterogeneous and can be divided into two subinterfaces, and each either of them includes its own pool of interactions: hACE2 Q24/Y83 + RBD N487, hACE2 H34 + RBD Y453, hACE2 E35 + + RBD Q493, and hACE2 D30 + RBD K417 for N-terminal relative to H1 hACE2 subinterface and hACE2 E37/R393 + + RBD Y505, hACE2 K353 + RBD Q498/G502, and hACE2 D355 + RBD T500 — for C-terminal. According to the considered N501Y mutation, changes are observed in the mentioned interaction patterns — hydrogen bonds of hACE2 Q42 + RBD Q498, hACE2 K31 + RBD Q493, and hACE2 K31 + RBD F490 are formed, and hACE2 H34 + RBD Y453 is lost. Similar aberrations, except for the hydrogen bond with F490, are observed in the case of the N501Y + Y453F vari-ant. Despite significant changes in the pool of interactions, the gross number of hydrogen bonds for the complexes of all three variants is relatively stable and ranges from 9 to 10. The defined interaction for all considered variants of RBD are characterized by the presence of a pocket between the subinterfaces, which is formed by the residues R403, Y453, Q493, S494, Y495, G496, F497, Q498, N501, and Y505 conditionally original variant. According to the results of the molecular dynamics simulation, the Y453F replacement has little effect on the overall topology of the cavity but sufficiently reduces the polarity of the pocket part of its localization, which leads to the impossibility of forming any polar interactions. In contrast, N501Y, due to a larger size of the tyrosine radical and the presence of parahydroxyl, forms two equivalent mutually exclusive hydrogen bonds with the carbonyls of the peptide groups G496 and Y495. Additional stabilization of Y501 is provided by interplanar stacking with Y505. In addition to the anchored position in ~ 25% of the trajectory, there is another “open” conformation Y501, at which the radical of this tyrosine does not interact with the rest of the protein. Conclusions. 1) The interface of the interaction of SARS-CoV-2 RBD with hACE2 is not continuous, and it can be conditionally divided into two subinterfaces: N-terminal and C-terminal. Either of them is characterized by its own pattern of connections and changes according to the RBD N501Y and Y453F replacements considered. However, despite the presence of significant molecular ear angements caused by N501Y and Y453F, the total number of hydrogen bonds is almost the same for all mutants. 2) Between the identified interaction subinterfaces, SARS-CoV-2 RBD contains a caveola, which due to its location may be potentially suitable for finding promising candidates for drugs aimed at inhib-iting the interaction of this protein with hACE2. In this case, the replacements of N501Y and Y453F have a significant impact on the topology of a particular pocket and can potentially modify the activity of inhibitors directed to this area. © Publisher PH «Akademperiodyka» of the NAS of Ukraine, 2022.

COVID-19 and the pursuit of supply chain resilience: reactions and “lessons learned” from logistics service providers (LSPs)

Purpose: The purpose of this paper is to provide new insights into the reactions and lessons learned with regard to the COVID-19 pandemic in terms of how logistics service providers (LSPs) managed to maintain supply chains resilience and what focus areas have been changed to keep operations functional and uphold financial stability. Design/methodology/approach: Based on data-gathering techniques in interpretive research this study collected primary data via semi-structured interviews, interviewing informants from selected LSPs that operate on a global scale. Findings: The results show that LSPs have built their reactions and actions to the COVID-19 outbreak around five main themes: “create revenue streams,” “enhance operational transport flexibility,” “enforce digitalization and data management,” “optimize logistics infrastructure” and “optimize personnel capacity.” These pillars build the foundation to LSP resilience that enables supply chains to stay resilient during an external shock of high impact and low probability. Originality/value: The results of this study provide insights into how LSPs have managed the downsides and found innovative ways to overcome operational and financial challenges during the COVID-19 outbreak. As one of the first studies that specially focuses on the role of LSPs during the COVID-19 pandemic, this study categorizes the LSPs’ reactions and provides a “lessons learned” framework from a managerial perspective. From a theoretical perspective, this paper discusses the strategic role of LSPs in supply chain management and thereby extends current supply chain literature with a focus on LSP resilience. © 2021, David M. Herold, Katarzyna Nowicka and Aneta Pluta-Zaremba and Sebastian Kummer.

Oil shocks and equity markets: The case of GCC and BRICS economies

This study analyzes the relationship between oil shocks and the equity markets of a group of world major oil producers and consumers encompassing both the GCC and BRICS economies. We employ a novel framework to decompose the oil shocks (demand, supply, and risk shocks) into their daily components. Subsequently, we also employ a network connectedness approach to investigate the static and time-varying connectedness of these shocks with equity markets. Our sample period ranges from January 6, 2005, to July 17, 2020. Empirical results show a medium connectedness between examined equity markets and oil shocks, in terms of returns and volatility, with an unpreceded level during the recent COVID-19 crisis. Furthermore, the volatility of oil-exporting countries contributes more to the volatility connectedness. Demand shock and risk shock are the main contributors to the connectedness. © 2021 Elsevier B.V.