A soft photonic bio‐adhesive material is designed with real‐time colorimetrical monitoring of switchable adhesion by integrating a responsive bio‐photonic matrix with mobile hydrogen‐binding ...networking. Synergetic materials sequencing creates a unique iridescent appearance directly coupled with both adhesive ability and shearing strength, in a highly reversible manner. The responsive photonic materials, having a physically hydrogen‐bonded chiral nematic organization, vary their adhesion strength due to a transition in cohesive and interfacial failure mechanism in humid surroundings. The bright color appearance shifts from blue to red to transparent and back due to a change in pitch length of the chiral helicoidal organization that also triggers coupled changes in both mechanical strength and interfacial adhesion. Such reversible strength‐adhesion‐iridescence triple‐coupling phenomenon is further explored for design of super‐strong switchable bio‐adhesives for synthetic/biological surfaces with quick remotely triggered sticky‐to‐nonsticky transitions, removable conformal soft stickers, and wound dressings with visual monitoring of the healing process, to colorimetric stickers for contaminated respiratory masks.
A soft photonic bio‐adhesive demonstrates large reversible changes in adhesion power and mechanical strength with concurrent self‐reporting colorimetric responses. This coupled behavior is derived by the humidity‐driven intercalation/removal of water molecules into a glucose‐containing hydrogen‐bonded polymer network within a liquid crystal polysaccharide matrix that triggers tightly correlated changes in mechanical strength, adhesion, and pitch length of the chiral nematic organization.
Multi-subunit SMC complexes control chromosome superstructure and promote chromosome disjunction, conceivably by actively translocating along DNA double helices. SMC subunits comprise an ABC ATPase ...“head” and a “hinge” dimerization domain connected by a 49 nm coiled-coil “arm.” The heads undergo ATP-dependent engagement and disengagement to drive SMC action on the chromosome. Here, we elucidate the architecture of prokaryotic Smc dimers by high-throughput cysteine cross-linking and crystallography. Co-alignment of the Smc arms tightly closes the interarm space and misaligns the Smc head domains at the end of the rod by close apposition of their ABC signature motifs. Sandwiching of ATP molecules between Smc heads requires them to substantially tilt and translate relative to each other, thereby opening up the Smc arms. We show that this mechanochemical gating reaction regulates chromosome targeting and propose a mechanism for DNA translocation based on the merging of DNA loops upon closure of Smc arms.
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•Crystallography and in vivo cross-linking reveal the architecture of prokaryotic Smc•Juxtaposition of the Smc arms misaligns the two Smc ATPase domains•Smc head engagement mechanically opens an interarm space•A model for DNA loop extrusion driven by the SMC ATPase cycle is presented
By combining high-throughput in vivo cysteine cross-linking and crystallography, Diebold-Durand et al. construct a high-resolution model of full-length prokaryotic Smc. It reveals that the rod-shaped Smc dimer lacks chambers for DNA and features misaligned head domains. Smc head engagement mechanically opens an interarm space.
Narrow bandgap n-type molecular semiconductors are relevant as key materials components for the fabrication near-infrared organic solar cells (OSCs) and organic photodetectors (OPDs). We thus ...designed nearly isostructural nonfullerene electron acceptors, except for the choice of solubilizing units, which absorb from 600 to 1100 nm. Specific molecules include CTIC-4F, CO1-4F, and COTIC-4F, whose optical bandgaps are 1.3, 1.2, and 1.1 eV, respectively. Modulation of intramolecular charge transfer characteristics was achieved by replacing alkoxy groups with alkyl groups on thiophene spacers that connect an electron-rich cyclopentadithiophene core to peripheral electron-poor fragments. OSCs incorporating CTIC-4F and CO1-4F with PTB7-Th achieve power conversion efficiencies of over 10% with short-circuit current densities as high as ∼25 mA·cm–2. The same blends achieve OPD responsivities of 0.52 A·W–1 at ∼920 nm. These findings highlight outstanding opportunities to tune further molecular design so that OPDs may ultimately compete with their silicon counterparts.
The assessment of the incubation period, which is the period between the infection and the illness onset, is essential to identify the sufficient isolation period for infectious diseases. In South ...Korea, a few cases of the coronavirus disease 2019 (COVID-19) were identified after the 14-day self-quarantine program, and the length of this quarantine has raised controversial issues for the Korean public health professionals.
We estimated the COVID-19 incubation period using the log-normal distribution from publicly available data. The data were obtained from the press release of the Busan city department of public health and news reports.
We collected and analysed information for 47 patients with a median age of 30. We estimated that the median incubation period was three days (95% Confidence Interval, 0.6–8.2). We also did not find any significant difference in the incubation period between males and females.
Our findings indicate that a 14-day self-quarantine program should be sufficient to prevent spreading in the infection of suspected individuals with COVID-19 in the community.
•In situ transesterification was successfully applied to wet microalgae.•Biodiesel was produced directly from wet microalgae in a single pot process.•The conversion yield reaches 91% using wet ...microalgae.
This work addresses a reliable in situ transesterification process which integrates lipid extraction from wet microalgae, and its conversion to biodiesel, with a yield higher than 90wt.%. This process enables single-step production of biodiesel from microalgae by mixing wet microalgal cells with solvent, methanol, and acid catalyst; and then heating them in one pot. The effects of reaction parameters such as reaction temperature, wet cell weight, reaction time, and catalyst volume on the conversion yield are investigated. This simultaneous extraction and transesterification of wet microalgae may enable a significant reduction in energy consumption by eliminating the drying process of algal cells and realize the economic production of biodiesel using wet microalgae.
The formation of uniform vitreous ice is a crucial step in the preparation of samples for cryogenic electron microscopy (cryo-EM). Despite the rapid technological progress in EM, controlling the ...thickness of vitreous ice on sample grids with reproducibility remains a major obstacle to obtaining high-quality data in cryo-EM imaging. The commonly employed classical blotting process faces the problem of excess water that cannot be absorbed by the filter paper, resulting in the formation of thick and heterogeneous ice. In this study, we propose a novel approach that combines the recently developed nanowire self-wicking technique with the classical blotting method to effectively control the thickness and homogeneity of vitrified ice. With simple procedures, we generated a copper oxide spike (COS) grid by inducing COSs on commercially available copper grids, which can effectively remove excess water during the blotting procedure without damaging the holey carbon membrane. The ice thickness could be controlled with good reproducibility compared to non-oxidized grids. Incorporated into other EM techniques, our new modification method is an effective option for obtaining high-quality data during cryo-EM imaging.
An oxyfluoride glass ceramic containing Eu2+-doped nepheline and LaF3 crystals was modified, with BaF2 replacing LaF3 up to 20 mole percent, and its luminescence change was monitored. With increasing ...BaF2 content, the greenish yellow emission centered at 540 nm under 400-nm excitation decreased, and a new afterglow emission from the modified ceramic was observed after removal of the excitation light source. X-ray diffraction (XRD) and transmission electron microscopy with energy dispersive spectroscopy (TEM-EDS) were used to investigate the changes in the crystalline phases within the glass matrix. Time dependent emission intensity was monitored to observe the afterglow, and the possible mechanism for the afterglow due to BaF2 addition was considered.
This study examines the effect of corporate governance on a company’s cash holdings, focusing on a firm’s compliance levels with core corporate governance indicators as outlined in the corporate ...governance report. Utilizing a random effect generalized least squares (GLS) regression model, this study evaluates 812 firm-year observations from Korean publicly traded companies covering the period 2018 to 2021. The results indicate that companies with robust governance structures generally maintain lower levels of cash holdings (coefficient = –0.0263, p-value = 0.044), corroborating the flexibility hypothesis. Moreover, higher compliance levels with governance matters concerning shareholder protection (coefficient = –0.0388, p-value = 0.090) and board of directors (coefficient = –0.0512, p-value = 0.052) are associated with reduced cash holdings. Further analysis, accounting for a firm’s organizational capital, underscores that the inverse relationship between corporate governance and cash holdings is more pronounced in organizations with lesser organizational capital (coefficient = –0.0548, p-value < 0.01). This study contributes empirical evidence showing that strict compliance with core corporate governance indicators, indicative of strong corporate governance, substantially affects a firm’s cash management. Additionally, this study offers valuable insights for regulatory authorities and investors and enhances the existing body of knowledge on the interplay between corporate governance and cash holdings.
Urban agriculture (UA) has been adopted as a strategy for food security in urban areas. This study identified the conditions for development of UA through a systematic review of UA case studies. It ...classified the enabling and constraining conditions within the three compositional elements of UA - necessity, ability, and opportunity - and determined the primary and secondary conditions for UA design by the country income group. The following conditions are required for both high-income and low/ middle-income countries: Motivation/public awareness; labour/human resources; policy and institutional infrastructure; social capital; and arable land and resources for farming. Agricultural education/training and research and technical development are needed for low and middle-income countries as the key secondary conditions. In high-income countries, a lack of farmers' knowledge and urban development are the main challenges to UA implementation. Therefore, the research findings could be meaningful evidence for making decisions and designing UA policies for sustainable food production.
To elucidate the intricate role that the sea surface microlayer (SML) and sea spray aerosols (SSAs) play in climate, understanding the chemical complexity of the SML and how it affects the ...physical–chemical properties of the microlayer and SSA are important to investigate. While the surface tension of the SML has been studied previously using conventional experimental tools, accurate measurements must be localized to the thickness of the air–liquid interface of the SML. Here we explore the atomic force microscopy (AFM) capabilities to quantify the surface tension of aqueous solution droplets with (sub)micrometer indentation depths into the interface. Sample droplets of hexanoic acid at molar concentrations ranging from 0.1 to 80 mM and SML from a recent wave flume study were investigated. A constant-radius AFM nanoneedle was used to probe ca. 200 μL droplets with 0.3–1.2 μm indentation depths. As a comparison, the surface tension of bulk samples was also measured using a conventional force tensiometer. The data for the hexanoic acid show an excellent overlap between the AFM and force tensiometer surface tension measurements. For the surface tension measurements of the SML, however, the measured values from the AFM were 2.5 mN/m lower than that from the force tensiometer, which was attributed to the structural and chemical complexity of the SML, differences in the probing depth for each method, and the time scale required for the surface film to restructure as the needle is retracted away from the liquid surface. Overall, the study confirmed the accuracy of the AFM method in quantifying the surface tension of aqueous solutions over a wide range of concentrations for surface-active organic compounds. The methodology can be further used to reveal small, yet important, differences in the surface tension of complex air–liquid interfaces such as liquid systems where the type and concentration of surfactants vary with the distance from the air–liquid interface. For such complex systems, AFM measurements of the surface tension as a function of the probing depth and pulling rate may reveal a sublayer film structure of the liquid interface.
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