Supply chain disruption recovery in the evolving crisis-Evidence from the early COVID-19 outbreak in China.

The speed of recovery from supply chain disruption has been identified as the predominant factor in building a resilient supply chain. However, COVID-19 as an example of an evolving crisis may challenge this assumption. Infection risk concerns may influence production resumption decision-making because any incidents of infection may lead to further shutdowns of production lines and undermine firms' long-term cash flows.

The effects of supply chain diversification during the COVID-19 crisis: Evidence from Chinese manufacturers.

Resilience amidst a crisis is vital to survival in the turbulent contemporary business environment. Diversifying the supply chain has been proposed as an important means to build this capability. However, there is insufficient empirical evidence demonstrating the merits of supply chain diversification during a crisis.

Macau's sustainability and diversification.

We analyze the socio-economic development of Macau after the return to Chinese sovereignty from the three dimensions of sustainability (economy, society, and environment). Macau's economy has both high growth and high volatility, mainly due to its unbalanced industrial structure and vulnerability to external shocks. During the COVID-19 pandemic, consumer confidence declined, due to the rising and high unemployment rate, while the environment has been relatively good since air quality became better.

Margin purchases, short sales and stock return volatility in China: Evidence from the COVID-19 outbreak.

In this paper, we investigate the effects of margin purchases and short sales on the return volatility in the Chinese stock market during the COVID-19 outbreak. We present two main findings. First, we show that stocks with higher level of margin-trading activity exhibit higher return volatility.

Prevention of intestinal adhesion and regeneration of abdominal wall tissue with meshes containing an electrostatically spun acellular dermal matrix (ADM)/silk fibroin (SF) fiber composite polypropylene mesh.

The repair of abdominal wall defects often requires the use of polypropylene (PP) as the main material. After a PP mesh is implanted in the body, contact with the intestine can cause adhesions between the intestine and the mesh, leading to serious complications such as intestinal fistula. In this study, we used electrostatic spinning technology to coat one side of PP meshes with an electrostatically spun isolating layer of acellular dermal matrix (ADM)/silk fibroin (SF) hybrid material.

C-H Insertion by Alkylidene Carbenes To Form 1,2,3-Triazines and Anionic [3 + 2] Dipolar Cycloadditions To Form Tetrazoles: Crucial Roles of Stereoelectronic and Steric Effects.

The synthesis of 1,2,3-triazines and bicyclic tetrazoles from α-azido ketones is described. The common intermediate generated from lithiated trimethylsilyldiazomethane and α-azido ketones diverges depending on the steric bulk of the substituents. The formation of 1,2,3-triazines via a C-H insertion of alkylidene carbene to form 3-azidocyclopropene, followed by its rearrangement, is supported by density functional theory calculations.

Silver-Catalyzed Selective Multicomponent Coupling Reactions of Arynes with Nitriles and Isonitriles.

Pathway selective aryne-based novel multicomponent coupling reactions with isonitriles and nitriles are described. Crucial to these reactions is the formation of a silver-aryne complex, which shows differential reactivity toward isonitriles and nitriles to form two different forms of -nitrilium organosilver arene species. Interception of the nitrilium of an aryne-isonitrile adduct with another isonitrile leads to the formation of benzocyclobutene-1,2-diimines, whereas the nitrilium of an aryne-nitrile adduct renders selective formation of 3-indol-3-imines or 3-iminoindolin-2-ol depending on the structure of the nitrile employed.

Silver-Catalyzed Annulation of Arynes with Nitriles for Synthesis of Structurally Diverse Quinazolines.

An efficient silver catalyzed annulation reaction of aryne with nitriles to generate quinazolines is described. Arynes generated from triynes or tetraynes through a hexadehydro Diels-Alder reaction readily participated in an [A + 2B] mode of annulation with nitriles in the presence of AgSbF catalyst. The mechanism was explored by DFT calculations, which supports the silver-catalyzed formation of nitrilium ion as a key intermediate.

The mechanism of the gold-catalyzed intramolecular [3 + 2]-cycloaddition of 1,6-diynes: a DFT study.

The gold-catalyzed [3 + 2] cycloaddition of areneyne-yne functionalities represents one of the most efficient methodologies for the construction of tricyclic ring systems under mild conditions. In the current report, a detailed mechanistic understanding of the reaction was achieved by DFT calculations. It was found that under the catalysis of gold(i), the initial cyclization occurs more favorably between the two alkynyl moieties via the 6-exo-dig pathway other than the arene-yne addition, which is the selectivity-determining step of the whole reaction and leads eventually to the [3 + 2] cycloadduct irreversibly by following the steps of arene-cation cyclization and proton transfer.

Alder-ene reactions driven by high steric strain and bond angle distortion to form benzocyclobutenes.

A unique aryne-based Alder-ene reaction to form benzocyclobutene is described. In this process, the thermodynamic barrier to form a four-membered ring is compensated by the relief of the strain energy of an aryne intermediate. On the other hand, the driving force to overcome the high kinetic barrier is provided by the gearing effect of the bulky substituent at the -position of the ene-donor alkene.

Consecutive Lossen rearrangement/transamidation reaction of hydroxamic acids under catalyst- and additive-free conditions.

The Lossen rearrangement is a classic process for transforming activated hydroxamic acids into isocyanate under basic or thermal conditions. In the current report we disclosed a consecutive Lossen rearrangement/transamidation reaction in which unactivated hydroxamic acids were converted into N-substituted formamides in a one-pot manner under catalyst- and additive-free conditions. One feature of this novel transformation is that the formamide plays triple roles in the reaction by acting as a readily available solvent, a promoter for additive-free Lossen rearrangement, and a source of the formyl group in the final products.