Enhancing the Chemical Stability of PL Cage: Transformation of the Chemically Labile Imine Cage into a Robust Carbamate Cage.

Herein, we report enhancement in chemical stability of the imine-based porphyrinic cage PL by converting it into a robust carbamate porphyrinic cage, c-PL, through a two-step post-synthetic modification process. First, the imine bonds in PL were reduced to form an amine-based cage, r-PL, followed by carbamation using N,N'-carbonyldiimidazole (CDI) to yield c-PL. The resulting carbamate cage exhibits high stability under acidic and basic conditions (pH 1-13) and in the presence of moisture.

Protomer of Imipramine Captured in Cucurbit[7]uril.

Small molecules possessing multiple proton-accessible sites are important not only to many biological systems but also to host-guest chemistry; their protonation states are causal to boosting or hindering specific host-guest interactions. However, determining the protonation site is not trivial. Herein, we conduct electrospray ionization ion mobility spectrometry-mass spectrometry to imipramine, a known molecule with two protonation sites, based on the introduction of cucurbit[7]uril as a host molecule.

Dramatically Enhanced Reactivity of Fullerenes and Tetrazine towards the Inverse-Electron-Demand Diels-Alder Reaction inside a Porous Porphyrinic Cage.

Inverse-electron-demand Diels-Alder reaction (IEDDA) between fullerenes and 1,2,4,5-tetrazine generally requires harsh conditions and long reaction times due to their strong electron-accepting nature. Herein, we report a dramatic enhancement in the reactivity of the fullerenes (C /C )-tetrazine reaction inside a porous Zn-porphyrinic cage (Zn-PB) under sustainable conditions by installing a tetrazine-based axle (LA) via metal-ligand coordination bond, which modulates the cavity size to facilitate the encapsulation of fullerenes. Upon encapsulation, the close proximity of fullerenes and the tetrazine group of LA dramatically increase their reactivity towards the IEDDA reaction to form fullerene-tetrazine adducts.

Reduction in urban atmospheric CO enhancement in Seoul, South Korea, resulting from social distancing policies during the COVID-19 pandemic.

With the spread of the COVID-19 virus globally, cities worldwide have implemented unprecedented social distancing policies to mitigate infection rates. Many studies have demonstrated that improved air quality and reduced carbon emissions have resulted from the COVID-19 pandemic. Yet, questions remain regarding changes in atmospheric CO concentrations because of the complex cycles involving the interaction of CO with the natural environment.

One-pot Synthesis of a Truncated Cone-shaped Porphyrin Macrocycle and Its Self-assembly into Permanent Porous Material.

Here, we report the synthesis of a truncated cone-shaped triangular porphyrinic macrocycle, P L , via a single step imine condensation of a cis-diaminophenylporphyrin and a bent dialdehyde-based linker as building units. X-ray diffraction analysis reveals that the truncated cone-shaped P L molecules are stacked on top of each other by π⋯π and CH⋯π interactions, to form 1.7 nm wide hollow columns in the solid state.

Bioinspired Gradient Conductivity and Stiffness for Ultrasensitive Electronic Skins.

Hierarchical and gradient structures in biological systems with special mechanical properties have inspired innovations in materials design for construction and mechanical applications. Analogous to the control of stress transfer in gradient mechanical structures, the control of electron transfer in gradient electrical structures should enable the development of high-performance electronics. This paper demonstrates a high performance electronic skin (e-skin) via the simultaneous control of tactile stress transfer to an active sensing area and the corresponding electrical current through the gradient structures.

High-Resolution Filtration Patterning of Silver Nanowire Electrodes for Flexible and Transparent Optoelectronic Devices.

Silver nanowire (AgNW) electrodes attract significant attention in flexible and transparent optoelectronic devices; however, high-resolution patterning of AgNW electrodes remains a considerable challenge. In this study, we have introduced a simple technique for high-resolution solution patterning of AgNW networks, based on simple filtration of AgNW solution on a patterned polyimide shadow mask. This solution process allows the smallest pattern size of AgNW electrodes, down to a width of 3.

Transfer Printing of Electronic Functions on Arbitrary Complex Surfaces.

Transfer printing of electronic functions on arbitrary surfaces is essential for next-generation applications of skin-attachable electronics, wearable sensors, and implantable/medical devices. For transfer printing of electronic functions on multidimensional surfaces, such as curved regions of the skin and different objects, various strategies have been devised based on the materials and structural design of electronic components and transfer stamps, such as ultrathin membranes or in-plane structures of electronic components, soft interfacial glues or adhesives between devices and surfaces, and smart transfer adhesives with bioinspired micro/nanostructures. These techniques enable high conformity of adhesion, mechanical robustness, and high compliance of electronic devices on arbitrary surfaces under mechanical deformation.

Gate-Tunable and Programmable n-InGaAs/Black Phosphorus Heterojunction Diodes.

Semiconductor heterostructures have enabled numerous applications in diodes, photodetectors, junction field-effect transistors, and memory devices. Two-dimensional (2D) materials and III-V compound semiconductors are two representative materials providing excellent heterojunction platforms for the fabrication of heterostructure devices. The marriage between these semiconductors with completely different crystal structures may enable a new heterojunction with unprecedented physical properties.

Preliminary Comparison of the Efficacy and Safety of Needle-Embedding Therapy with Acupuncture for Atopic Dermatitis Patients.

Objectives: Among Traditional Korean Medicine approaches, needle-embedding therapy is used in various fields and consistently studied; however, there have been no clinical studies of the treatment of adult atopic dermatitis (AD) with needle-embedding therapy. Thus, there is a need to investigate the effects of needle-embedding therapy for treatment of AD. This study was performed to identify possible effects of needle-embedding therapy at Quchi acupoint (LI11) on AD and to compare these effects with those of acupuncture therapy.

Nanometric Water Channels in Water-in-Salt Lithium Ion Battery Electrolyte.

Lithium-ion batteries (LIBs) have been deployed in a wide range of energy-storage applications and helped to revolutionize technological development. Recently, a lithium ion battery that uses superconcentrated salt water as its electrolyte has been developed. However, the role of water in facilitating fast ion transport in such highly concentrated electrolyte solutions is not fully understood yet.

Fano cavity test for electron Monte Carlo transport algorithms in magnetic fields: comparison between EGSnrc, PENELOPE, MCNP6 and Geant4.

A Fano cavity test was performed for four general-purpose Monte Carlo codes, EGSnrc, PENELOPE, MCNP6 and Geant4 to evaluate the accuracy of their electron transport algorithms in magnetic fields. In the simulations, a plane-parallel ionization chamber was modelled as a circular gas disk sandwiched between two circular solid wall disks. It was assumed that an isotropic and uniform line source per unit mass along the central axis of the gas and solid emits mono-energetic electrons with energies 0.

Transparent and conductive nanomembranes with orthogonal silver nanowire arrays for skin-attachable loudspeakers and microphones.

We demonstrate ultrathin, transparent, and conductive hybrid nanomembranes (NMs) with nanoscale thickness, consisting of an orthogonal silver nanowire array embedded in a polymer matrix. Hybrid NMs significantly enhance the electrical and mechanical properties of ultrathin polymer NMs, which can be intimately attached to human skin. As a proof of concept, we present a skin-attachable NM loudspeaker, which exhibits a significant enhancement in thermoacoustic capabilities without any significant heat loss from the substrate.

Asymmetric polar localization dynamics of the serine chemoreceptor protein Tsr in Escherichia coli.

The spatial location of proteins in living cells can be critical for their function. For example, the E. coli chemotaxis machinery is localized to the cell poles.

Flexible Ferroelectric Sensors with Ultrahigh Pressure Sensitivity and Linear Response over Exceptionally Broad Pressure Range.

Flexible pressure sensors with a high sensitivity over a broad linear range can simplify wearable sensing systems without additional signal processing for the linear output, enabling device miniaturization and low power consumption. Here, we demonstrate a flexible ferroelectric sensor with ultrahigh pressure sensitivity and linear response over an exceptionally broad pressure range based on the material and structural design of ferroelectric composites with a multilayer interlocked microdome geometry. Due to the stress concentration between interlocked microdome arrays and increased contact area in the multilayer design, the flexible ferroelectric sensors could perceive static/dynamic pressure with high sensitivity (47.

Graph Theory and Ion and Molecular Aggregation in Aqueous Solutions.

In molecular and cellular biology, dissolved ions and molecules have decisive effects on chemical and biological reactions, conformational stabilities, and functions of small to large biomolecules. Despite major efforts, the current state of understanding of the effects of specific ions, osmolytes, and bioprotecting sugars on the structure and dynamics of water H-bonding networks and proteins is not yet satisfactory. Recently, to gain deeper insight into this subject, we studied various aggregation processes of ions and molecules in high-concentration salt, osmolyte, and sugar solutions with time-resolved vibrational spectroscopy and molecular dynamics simulation methods.

Ultrafast fluxional exchange dynamics in electrolyte solvation sheath of lithium ion battery.

Lithium cation is the charge carrier in lithium-ion battery. Electrolyte solution in lithium-ion battery is usually based on mixed solvents consisting of polar carbonates with different aliphatic chains. Despite various experimental evidences indicating that lithium ion forms a rigid and stable solvation sheath through electrostatic interactions with polar carbonates, both the lithium solvation structure and more importantly fluctuation dynamics and functional role of carbonate solvent molecules have not been fully elucidated yet with femtosecond vibrational spectroscopic methods.

High-Performance MoS/CuO Nanosheet-on-One-Dimensional Heterojunction Photodetectors.

van der Waals heterostructures based on stacked two-dimensional (2D) materials provide novel device structures enabling high-performance electronic and optoelectronic devices. While 2D-2D or 2D-bulk heterostructures have been largely explored for fundamental understanding and novel device applications, 2D-one-dimensional (1D) heterostructures have been rarely studied because of the difficulty in achieving high-quality heterojunctions between 2D and 1D structures. In this study, we introduce nanosheet-on-1D van der Waals heterostructure photodetectors based on a wet-transfer printing of a MoS nanosheet on top of a CuO nanowire (NW).

Computational Vibrational Spectroscopy of HDO in Osmolyte-Water Solutions.

The IR absorption and time-resolved IR spectroscopy of the OD stretch mode of HDO in water was successfully used to study osmolyte effects on water H-bonding network. Protecting osmolytes such as sorbitol and trimethylglycine (TMG) make the vibrational OD stretch band red-shifted, whereas urea affects the OD band marginally. Furthermore, we recently showed that, even though sorbitol and TMG cause a slow-down of HDO rotation in their aqueous solutions, urea does not induce any change in the rotational relaxation of HDO in aqueous urea solutions even at high concentrations.

Octopus-Inspired Smart Adhesive Pads for Transfer Printing of Semiconducting Nanomembranes.

By mimicking muscle actuation to control cavity-pressure-induced adhesion of octopus suckers, smart adhesive pads are developed in which the thermoresponsive actuation of a hydrogel layer on elastomeric microcavity pads enables excellent switchable adhesion in response to a thermal stimulus (maximum adhesive strength: 94 kPa, adhesion switching ratio: ≈293 for temperature change between 22 and 61 °C).

Spectral Graph Analyses of Water Hydrogen-Bonding Network and Osmolyte Aggregate Structures in Osmolyte-Water Solutions.

Recently, it was shown that the spectral graph theory is exceptionally useful for understanding not only morphological structural differences in ion aggregates but also similarities between an ion network and a water H-bonding network in highly concentrated salt solutions. Here, we present spectral graph analysis results on osmolyte aggregates and water H-bonding network structures in aqueous renal osmolyte solutions. The quantitative analyses of the adjacency matrices that are graph-theoretical representations of aggregates of osmolyte molecules and water H-bond structures provide the ensemble average eigenvalue spectra and degree distribution.

Modulation of the Hydrogen Bonding Structure of Water by Renal Osmolytes.

Osmolytes are an integral part of living organism, e.g., the kidney uses sorbitol, trimethylglycine, taurine and myo-inositol to counter the deleterious effects of urea and salt.

Vacuum-induced wrinkle arrays of InGaAs semiconductor nanomembranes on polydimethylsiloxane microwell arrays.

Tunable surface morphology in III-V semiconductor nanomembranes provides opportunities to modulate electronic structures and light interactions of semiconductors. Here, we introduce a vacuum-induced wrinkling method for the formation of ordered wrinkles in InGaAs nanomembranes (thickness, 42 nm) on PDMS microwell arrays as a strategy for deterministic and multidirectional wrinkle engineering of semiconductor nanomembranes. In this approach, a vacuum-induced pressure difference between the outer and inner sides of the microwell patterns covered with nanomembranes leads to bulging of the nanomembranes at the predefined microwells, which, in turn, results in stretch-induced wrinkle formation of the nanomembranes between the microwells.

Dynamics of the serine chemoreceptor in the Escherichia coli inner membrane: a high-speed single-molecule tracking study.

We investigated the mobility of the polar localized serine chemoreceptor, Tsr, labeled by the fluorescent protein Venus in the inner membrane of live Escherichia coli cells at observation rates up to 1000 Hz. A fraction (7%) of all Tsr molecules shows free diffusion over the entire cell surface with an average diffusion coefficient of 0.40 ± 0.