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.
As a photophysical phenomenon, aggregation-induced emission (AIE) was proposed by Tang in 2001. Due to their excellent fluorescence emission performance, AIEgens and AIE-based fluorescence materials ...have shown great application potential in a wide range of science fields. Hence, exploring new AIEgens and construction of novel AIE materials are especially vital. In addition, as a new class of macrocyclic hosts, pillararenes have shown excellent performance in supramolecular chemistry. Interestingly, pillararenes also exhibited fairly bright application prospects in the AIE area: firstly, some research studies suggested that pillararenes could serve as a novel AIEgen with considerable fluorescence emission in the aggregated state; moreover, they could also participate in the construction of AIE materials and have potential application in various areas. In this review, we summarised the recent development of pillararene-based AIE materials from the following aspects: pillararenes as novel AIEgens, the
TPE
functionalized pillararene-based AIE materials, the pillararene-based AIE materials constructed by supramolecular assembly, and the functionalized pseudo-pillararene-based AIE materials. It is hoped that this feature article will attract increasing attention and pave a new way for the development and application of pillar
n
arene-based AIE materials in more fields.
The pillararene-based AIEgens and AIE materials, constructed using different assembly forms, show attractive applications in various areas.
Toward promising candidates of quantum information processing, the rapid development of lanthanide-based single-molecule magnets (Ln-SMMs) highlights design strategies in consideration of the local ...symmetry of lanthanide ions. In this review, crystal-field theory is employed to demonstrate the electronic structures according to the semiquantitative electrostatic model. Then, specific symmetry elements are analysed for the elimination of transverse crystal fields and quantum tunnelling of magnetization (QTM). In this way, high-performance Ln-SMMs can be designed to enable extremely slow relaxation of magnetization, namely magnetic blocking; however, their practical magnetic characterization becomes increasingly challenging. Therefore, we will attempt to interpret the experimental behaviours and clarify some issues in detail. Finally, representative Ln-SMMs with specific local symmetries are summarized in combination with the discussion on the symmetry strategies, and some of the underlying questions are put forward.
Based on crystal-field theory, design strategies in consideration of local symmetry are highlighted for lanthanide-based single-molecule magnets, accompanied by practical concerns about magnetic studies and representative cases.
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.
Single-molecule magnets (SMMs) containing only one metal center may represent the lower size limit for molecule-based magnetic information storage materials. Their current drawback is that all SMMs ...require liquid-helium cooling to show magnetic memory effects. We now report a chemical strategy to access the dysprosium metallocene cation (Cp
)Dy(Cp*)
(Cp
, penta-iso-propylcyclopentadienyl; Cp
pentamethylcyclopentadienyl), which displays magnetic hysteresis above liquid-nitrogen temperatures. An effective energy barrier to reversal of the magnetization of
= 1541 wave number is also measured. The magnetic blocking temperature of
= 80 kelvin for this cation overcomes an essential barrier toward the development of nanomagnet devices that function at practical temperatures.
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