Over the past few years, Bitcoin has emerged as the first decentralized, global currency. The rise of Bitcoin has brought attention not only to digital currencies but also to the underlying ...technology empowering digital currencies: blockchain technology. A blockchain is a distributed ledger that records and secures transactions in a peer-to-peer network. Besides empowering digital currencies, blockchain technology has given innovators the capability of creating digital tokens to represent scarce assets, potentially reshaping the landscape of entrepreneurship and innovation. Blockchain tokens may democratize (1) entrepreneurship by giving entrepreneurs new ways to raise funds and engage stakeholders, and (2) innovation by giving innovators a new way to develop, deploy, and diffuse decentralized applications. Blockchain technology and tokens have sparked a new wave of innovation, which may start to revolutionize entrepreneurship and innovation.
Recurrent events, including cardiovascular events, are commonly observed in biomedical studies. Understanding the effects of various treatments on recurrent events and investigating the underlying ...mediation mechanisms by which treatments may reduce the frequency of recurrent events are crucial tasks for researchers. Although causal inference methods for recurrent event data have been proposed, they cannot be used to assess mediation. This study proposed a novel methodology of causal mediation analysis that accommodates recurrent outcomes of interest in a given individual. A formal definition of causal estimands (direct and indirect effects) within a counterfactual framework is given, and empirical expressions for these effects are identified. To estimate these effects, a semiparametric estimator with triple robustness against model misspecification was developed. The proposed methodology was demonstrated in a real‐world application. The method was applied to measure the effects of two diabetes drugs on the recurrence of cardiovascular disease and to examine the mediating role of kidney function in this process.
Antibiotics played an important role in controlling the development of enteric infection. However, the emergence of antibiotic resistance and gut dysbiosis led to a growing interest in the use of ...natural antimicrobial agents as alternatives for therapy and disinfection. Chitosan is a nontoxic natural antimicrobial polymer and is approved by GRAS (Generally Recognized as Safe by the United States Food and Drug Administration). Chitosan and chitosan derivatives can kill microbes by neutralizing negative charges on the microbial surface. Besides, chemical modifications give chitosan derivatives better water solubility and antimicrobial property. This review gives an overview of the preparation of chitosan, its derivatives, and the conjugates with other polymers and nanoparticles with better antimicrobial properties, explains the direct and indirect mechanisms of action of chitosan, and summarizes current treatment for enteric infections as well as the role of chitosan and chitosan derivatives in the antimicrobial agents in enteric infections. Finally, we suggested future directions for further research to improve the treatment of enteric infections and to develop more useful chitosan derivatives and conjugates.
By 27 February 2020, the outbreak of coronavirus disease 2019 (COVID‐19) caused 82 623 confirmed cases and 2858 deaths globally, more than severe acute respiratory syndrome (SARS) (8273 cases, 775 ...deaths) and Middle East respiratory syndrome (MERS) (1139 cases, 431 deaths) caused in 2003 and 2013, respectively. COVID‐19 has spread to 46 countries internationally. Total fatality rate of COVID‐19 is estimated at 3.46% by far based on published data from the Chinese Center for Disease Control and Prevention (China CDC). Average incubation period of COVID‐19 is around 6.4 days, ranges from 0 to 24 days. The basic reproductive number (R0) of COVID‐19 ranges from 2 to 3.5 at the early phase regardless of different prediction models, which is higher than SARS and MERS. A study from China CDC showed majority of patients (80.9%) were considered asymptomatic or mild pneumonia but released large amounts of viruses at the early phase of infection, which posed enormous challenges for containing the spread of COVID‐19. Nosocomial transmission was another severe problem. A total of 3019 health workers were infected by 12 February 2020, which accounted for 3.83% of total number of infections, and extremely burdened the health system, especially in Wuhan. Limited epidemiological and clinical data suggest that the disease spectrum of COVID‐19 may differ from SARS or MERS. We summarize latest literatures on genetic, epidemiological, and clinical features of COVID‐19 in comparison to SARS and MERS and emphasize special measures on diagnosis and potential interventions. This review will improve our understanding of the unique features of COVID‐19 and enhance our control measures in the future.
Dehydrogenative annulation reactions are among the most straightforward and efficient approach for the preparation of cyclic structures. However, the applications of this strategy for the synthesis ...of saturated heterocycles have been rare. In addition, reported dehydrogenative bond-forming reactions commonly employ stoichiometric chemical oxidants, the use of which reduces the sustainability of the synthesis and brings safety and environmental issues. Herein, we report an organocatalyzed electrochemical dehydrogenative annulation reaction of alkenes with 1,2- and 1,3-diols for the synthesis of 1,4-dioxane and 1,4-dioxepane derivatives. The combination of electrochemistry and redox catalysis using an organic catalyst allows the electrosynthesis to proceed under transition metal- and oxidizing reagent-free conditions. In addition, the electrolytic method has a broad substrate scope and is compatible with many common functional groups, providing an efficient and straightforward access to functionalized 1,4-dioxane and 1,4-dioxepane products with diverse substitution patterns.
ion of a chloride ligand from the dysprosium metallocene (Cpttt)2DyCl (1Dy Cpttt=1,2,4‐tri(tert‐butyl)cyclopentadienide) by the triethylsilylium cation produces the first base‐free rare‐earth ...metallocenium cation (Cpttt)2Dy+ (2Dy) as a salt of the non‐coordinating B(C6F5)4− anion. Magnetic measurements reveal that 2DyB(C6F5)4 is an SMM with a record anisotropy barrier up to 1277 cm−1 (1837 K) in zero field and a record magnetic blocking temperature of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low‐lying Kramers doublets correspond to a well‐defined MJ value, with no significant mixing even in the higher doublets.
SMMashing: A dysprosium(III) metallocenium cation is a single‐molecule magnet (SMM) with a record anisotropy barrier of 1277 cm−1 and record magnetic blocking up to 60 K, including hysteresis with coercivity.
Heterojunction engineering, especially 2D/2D heterojunctions, is regarded as a quite promising strategy to manipulate the photocatalytic performance of semiconductor catalysts. In this manuscript, a ...direct Z‐scheme 2D/2D heterojunction of CsPbBr3/Bi2WO6 is designed and fabricated by a simple electrostatic self‐assembly process. By using ultrathin nanosheets with several atomic layers as the building blocks, a close CsPbBr3/Bi2WO6 heterointerface over large area with quite a short charge transport distance is obtained, which enables a valid Z‐scheme interfacial charge transfer between Bi2WO6 and CsPbBr3 and thus boosts charge separation. The CsPbBr3/Bi2WO6 heterojunction exhibits a superior photocatalytic performance toward CO2 reduction. By incorporating Pt nanoparticles as the cocatalyst, a high photoelectron consumption rate of 324.0 µmol g−1 h−1 under AM 1.5G irradiation (150 mW cm−2) is obtained, which is 12.2 fold higher than that of CsPbBr3 nanosheets. Moreover, a stable product yield of up to 1582.0 µmol g−1 and electron consumption yield of 8603.0 µmol g−1 for photocatalytic CO2 reduction to CO (11.4%) and CH4 (84.3%) can be achieved after 30 h of continuous catalytic reaction. The accelerated photogenerated charge transfer and spatial charge separation are investigated in detail by ultrafast spectra, photoelectrochemical test, and Kelvin probe force microscopy.
A Z‐Scheme 2D/2D heterojunction of CsPbBr3/Bi2WO6 is fabricated using a simple electrostatic assembly process. The as‐formed heterojunction possesses a large interface contact area and quite a short charge transport distance, which enable efficient Z‐scheme charge transfer and separation between Bi2WO6 and CsPbBr3, as well as remarkably enhanced performance toward photocatalytic CO2 reduction.
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