Dehydration process in NaCl solutions under various external electric fields

Ionic motions at solid-liquid interface in supersaturated NaCl solutions have been investigated by molecular dynamics (MD) simulation for understanding crystal growth processes. The density profile in the vicinity of the interfaces between NaCl(100) and the supersaturated NaCl solution was calculated. Diffusion coefficients of water molecules in the solution were estimated as a function of distance from the crystal interface. It turned out that the structure and dynamics of the solution in the interfaces was different from those of bulk solution owing to electric fields depending on the surface charge. Therefore, the electric field was applied to the supersaturated solutions and dehydration phenomenon occurring in the process of the crystal growth was discussed. As the electric field increased, it was observed that the Na⁺ keeping strongly hydration structure broke out by the electric force. In supersaturated concentration, the solution structure is significantly different from that of dilution and has a complicated structure with hydration ions and clusters of NaCl. If the electric fields were applied to the solutions, the breakout of hydration structure was not affected with increasing the supersaturated ratio. This reason is that the cluster structures are destroyed by the electric force. The situation depends on the electric field or crystal surface structure.     

Rhodium‐Catalyzed Highly Diastereo‐ and Enantioselective Synthesis of a Configurationally Stable S‐Shaped Double Helicene‐Like Molecule

An S‐shaped double helicene‐like molecule (>99 % ee), possessing stable helical chirality, has been synthesized by the rhodium(I)/difluorphos complex‐catalyzed highly diastereo‐ and enantioselective intramolecular double [2+2+2] cycloaddition of a 2‐naphthol‐ and benzene‐linked hexayne. The collision between two terminal naphthalene rings destabilizes the helical chirality of the S‐shaped double helicene‐like molecule, but the introduction of two additional fused benzene rings significantly increases the configurational stability. Thus, no epimerization and racemization were observed even at 100 °C. The enantiopure S‐shaped double helicene‐like molecule forms a trimer through the multiple C?H???π and C?H???O interactions in the solid‐state. The trimers stack to form columnar packing structures, in which neighboring stacks have opposite dipole directions. The accumulation of helical structures in the same direction in the S‐shaped double helicene‐like molecule enhanced the chiroptical properties.     

Fluorogenic Probe Using a Mislow–Evans Rearrangement for Real‐Time Imaging of Hydrogen Peroxide

Hydrogen peroxide (H₂O₂) mediates the biology of wound healing, apoptosis, inflammation, etc. H₂O₂ has been fluorometrically imaged with protein‐ or small‐molecule‐based probes. However, only protein‐based probes have afforded temporal insights within seconds. Small‐molecule‐based electrophilic probes for H₂O₂ require many minutes for a sufficient response in biological systems. Here, we report a fluorogenic probe that selectively undergoes a [2,3]‐sigmatropic rearrangement (seleno‐Mislow‐Evans rearrangement) with H₂O₂, followed by acetal hydrolysis, to produce a green fluorescent molecule in seconds. Unlike other electrophilic probes, the current probe acts as a nucleophile. The fast kinetics enabled real‐time imaging of H₂O₂ produced in endothelial cells in 8 seconds (much earlier than previously shown) and H₂O₂ in a zebrafish wound healing model. This work may provide a platform for endogenous H₂O₂ detection in real time with chemical probes.     

Self-Boosting Catalytic Nanoreactors Integrated with Triggerable Crosslinking Membrane Networks for Initiation of Immunogenic Cell Death by Pyroptosis

Synthetic polymer vesicles spur novel strategies for producing intelligent nanodevices with precise and specific functions. Engineering vesicular nanodevices with tunable permeability by a general platform without involving trade-offs between structural integrity, flexibility, and functionality remains challenging. Herein, we present a general strategy to construct responsive nanoreactors based on polyion complex vesicles by integrating stimuli-responsive linkers into a crosslinking membrane network. The formulated ROS-responsive nanoreactor with self-boosting catalytic glucose oxidation could protect glucose oxidase (GOD) to achieve cytocidal function by oxidative stress induction and glucose starvation, which is ascribed to stimuli-responsive vesicle expansion without fracture and size-selective cargo release behavior. The GOD-loaded therapeutic nanoreactor induced an immunostimulatory form of cell death by pyroptosis, which has the great potential to prime anti-tumor immune responses.     

Induction of Secondary Structure through Micellization of an Oppositely Charged Pair of Homochiral Block‐ and Homopolypeptides in an Aqueous Medium

Polyion complex (PIC) formation is an attractive method for obtaining molecular assemblies owing to their facile fabrication process in aqueous media, but more insights are required in order to control the higher‐dimensional structures of polypeptide‐based PICs. Herein, the PIC formation behavior of oppositely charged homochiral polypeptides, poly‐l ‐lysine and poly(ethylene glycol)‐b‐poly(l ‐glutamate) (PEG‐PLG), and their secondary structures are carefully studied in water. PIC formation takes place in a polymer concentration‐dependent manner, and clear β‐sheet formation is observed at polymer concentrations ≥0.3 mg mL⁻¹. The results also confirm that multimolecular aggregation is a prerequisite for β‐sheet formation, which indicates that the inner hydrophobic environment of PICs is favorable for β‐sheet formation. Furthermore, the PEG weight fraction, stereoregularity of the polypeptide, and ionic strength of the solutions are found to be key factors for generating a secondary structure, presumably because these factors can contribute to the tuning of the inner environment of PICs. This method of producing water‐soluble nanoassemblies from oppositely charged polypeptides may expedite self‐assembly studies in biological systems and be incorporated into various molecular systems to exploit protein‐mimicking features.

     

Immersion angle dependence of the resonant-frequency shift of the quartz crystal microbalance in a liquid: effects of longitudinal wave

We investigated the effects of the longitudinal wave on the immersion angle dependence of the resonant-frequency shift, ΔF, of the quartz crystal microbalance, QCM. In order to study exactly the effects, we employed the three types of cells: normal cell, cell with the glass beads and cell with sponge. The longitudinal wave exists in the normal cell. On the other hand, both the cell with the glass beads and the cell with sponge eliminate the longitudinal wave. As results, we have found that the tendencies of ΔF are the same in the three types of cells. That is, we conclude that the longitudinal wave does not have effects on the immersion angle dependence of ΔF.     

Algebraic independence results for the values of certain Mahler functions and their application to infinite products

In this paper we establish algebraic independence criteria for the values at an algebraic point of Mahler functions each of which satisfies either a multiplicative type of functional equation or an additive one. As application we construct, using a linear recurrence sequence, an entire function defined by an infinite product such that its values as well as its all successive derivatives at algebraic points other than its zeroes are algebraically independent. Zeroes of such an entire function form a subsequence of the linear recurrence sequence. We prove the algebraic independency by reducing those values at algebraic points to those of Mahler functions.