Comparison between Abel test stability and thermal decomposition behavior of nitrocellulose

Journal of Thermal Analysis and Calorimetry - Nitrocellulose (NC) is prone to spontaneous decomposition with exothermic heat release and thus is generally evaluated for stability during the storage...     

Formation of Supramolecular Nanostructures through in Situ Self-Assembly and Post-Assembly Modification of a Biocatalytically Constructed Dipeptide Hydrazide**

Aqueous self-assembly of short peptides has attracted growing attention for the construction of supramolecular materials for various bioapplications. Herein, we describe how the thermolysin-assisted biocatalytic construction of a dipeptide hydrazide from an N-protected amino acid and an amino acid hydrazide leads to the formation of thermally stable supramolecular hydrogels. In addition, we demonstrate the post-assembly modification of the supramolecular architectures constructed in situ tethering hydrazide groups as a chemical handle by means of fluorescence imaging.     

Change in motor cortex activation for muscle release by motor learning

For central nervous system disorders'' rehabilitation, it is important to accurately understand motor control and implement an appropriate motor learning process to induce neuroplastic changes. The neurophysiological studies have revealed that neural control mechanisms are crucial during both the onset of muscular activities and muscle release after contraction. When performing various movements during daily activities, muscle relaxation control enables precise force output and timing control. Moreover, surround inhibition is a functional mechanism in the motor system. Surround inhibition of the motor system may be involved in the selective execution of desired movements. This review demonstrates cortical excitability resulting from motor learning, movement control mechanisms including muscle relaxation and the suppression of nontarget muscle groups, and the voluntary drive''s importance that is required for movement.     

Optimizing Charge Switching in Membrane Lytic Peptides for Endosomal Release of Biomacromolecules

Endocytic pathways are practical routes for the intracellular delivery of biomacromolecules. Along with this, effective strategies for endosomal cargo release into the cytosol are desired to achieve successful delivery. Focusing on compositional differences between the cell and endosomal membranes and the pH decrease within endosomes, we designed the lipid-sensitive and pH-responsive endosome-lytic peptide HAad. This peptide contains aminoadipic acid (Aad) residues, which serve as a safety catch for preferential permeabilization of endosomal membranes over cell membranes, and His-to-Ala substitutions enhance the endosomolytic activity. The ability of HAad to destabilize endosomal membranes was supported by model studies using large unilamellar vesicles (LUVs) and by increased intracellular delivery of biomacromolecules (including antibodies) into live cells. Cerebral ventricle injection of Cre recombinase with HAad led to Cre/loxP recombination in a mouse model, thus demonstrating potential applicability of HAad in vivo.     

Redox-Induced Modulation of Exchange Interaction in a High-Spin Ground-State Diradical/Triradical System

A triplet ground-state diradical molecule, bis(nitronyl nitroxide)-substituted diphenyldihydrophenazine ( 1 ^..), that can be converted into a one-electron oxidized species, 1 ^{… +} , in the quartet ground state has been developed. Surprisingly, these species, 1 ^.. and 1 ^{… +} , can be used under ambient conditions because they are reasonably stable under aerobic conditions, even in solution. The temperature-dependent magnetic susceptibilities reveal that 1 ^.. and 1 ^{… +} are in the triplet state, with a weak exchange interaction (J₁/k_B = +3.1 K) and quartet ground state with a strong exchange interaction (J₂/k_B = +160 K), respectively. The interconversion between the neutral and one-electron oxidized species can be realized through electrochemical reactions. Significantly different absorption bands in the near-IR region newly appeared in the electronic spectra acquired during electrochemical oxidation/reduction.     

A far-red emitting probe for unambiguous detection of mobile zinc in acidic vesicles and deep tissue

Imaging mobile zinc in acidic environments remains challenging because most small-molecule optical probes display pH-dependent fluorescence. Here we report a reaction-based sensor that detects mobile zinc unambiguously at low pH. The sensor responds reversibly and with a large dynamic range to exogenously applied Zn²⁺ in lysosomes of HeLa cells, endogenous Zn²⁺ in insulin granules of MIN6 cells, and zinc-rich mossy fiber boutons in hippocampal tissue from mice. This long-wavelength probe is compatible with the green-fluorescent protein, enabling multicolor imaging, and facilitates visualization of mossy fiber boutons at depths of >100 μm, as demonstrated by studies in live tissue employing two-photon microscopy.     

Micro‐ and Nano‐Liquid Phases Coexistent with Ice as Separation and Reaction Media.

Ice has a variety of scientifically interesting features, some of which have not been reasonably interpreted despite substantial efforts by researchers. Most chemical studies of ice have focused on the elucidation of its physicochemical nature and its roles in the natural environment. Ice often contains impurities, such as salts, and in such cases, a liquid phase coexists with solid ice over a wide temperature range. This impure ice also acts as a cryoreactor, governing the circulation of chemical species of environmental importance. Reactions and phenomena occurring in this liquid phase show features different from those seen in normal bulk aqueous solutions. In the present account, we discuss the chemical characteristics of the liquid phase that develops in a frozen aqueous phase and show how novel analytical systems can be designed based on he features of the liquid phase which are predictable in some cases but unpredictable in others.