Topological measurement of deep neural networks using persistent homology

Annals of Mathematics and Artificial Intelligence - The inner representation of deep neural networks (DNNs) is indecipherable, which makes it difficult to tune DNN models, control their training...     

Residual Stress in Siliceous Glass Between Mullite Crystals

A birefringence of siliceous glass, which is coexisting with mullite crystals, was studied by an optical polarizing microscope. The cause of the birefringence was assumed to be the residual stress induced by a large contraction difference between the mullite and glass on cooling. The stress has been evaluated to be as high as—0.3 GPa, and to correspond to the elastic one which began to develop at the glass transition point.     

Electrochemical investigation of uranium β-diketonates for all-uranium redox flow battery

The redox flow battery using uranium as the negative and the positive active materials in polar aprotic solvents was proposed. In order to establish the guiding principle for the uranium compounds as the active materials, the investigation of uranium β-diketonate complexes was conducted on (i) the solubility of active materials, (ii) the electrode reaction of U(VI) and U(IV) β-diketonate complexes and (iii) the estimation of the open circuit voltage of the battery. The solubilities of higher than 0.8 mol dm⁻³ of U(VI) complexes and higher than 0.4 mol dm⁻³ of a U(IV) complex were obtained in the solvents. The electrode reactions of U(pta)₄, UO₂(dpm)₂, UO₂(fod)₂ and UO₂(pta)₂ were first studied and the redox potentials of uranium β-diketonates were thermodynamically discussed. The open circuit voltage is estimated more than 1 V by using Hacac or Hdpm. The larger open circuit voltage is expected when a ligand with the larger basicity is used.     

Controlling Pyrene Association in DNA Duplexes by B- to Z-DNA Transitions

B- to Z-DNA transitions play a crucial role in biological systems and have attracted the interest of researchers for their applications in DNA nanotechnology. DNA and DNA analogues have also been used as templates to construct helical chromophore associations with π interactions. In this work, the B- to Z-DNA transition-induced switching of pyrene in an association manner was evaluated using DNA duplexes with non-nucleosidic pyrene residues in the middle of d(CG) repeat sequences. One of the pyrene-labeled DNAs was shown to exhibit inverted exciton coupled circular dichroism signals upon pyrene association through a B- to Z-DNA transition. This observation indicates that pyrene association switches the DNA conformation from right- to left-handed. Interestingly, the fluorescence of the pyrene-labeled DNA duplex also dynamically changed upon switching of the pyrene in an association-based manner. Taken together, these studies demonstrate that pyrene-labeled DNA shows promise as a chiroptical molecular switch.     

DNA‐Templated Synthesis of Perylenediimide Stacks Utilizing Abasic Sites as Binding Pockets and Reactive Sites

DNA is considered to be a promising biomolecule as a template and scaffold for arranging and organizing functional molecules on the nanoscale. The construction and evaluation of DNAs containing multiple functional molecules that are useful for optoelectronic devices and sensors has been studied. In this paper we report the efficient incorporation of perylenediimide (PDI) units into DNA by using abasic sites both as binding sites and as reactive sites and the construction of PDI stacks within the DNA structure, accomplished through the preorganization of the PDI units in the hydrophobic pocket within the DNA. Our approach could become a valuable method for construction of DNA/chromophore hybrid structures potentially useful for the design of DNA‐based devices and biosensors.     

Preparation of iron phthalocyanine catalyzed carbon electrodes by chemical modification

A technique for chemically bonding and polymerizing organometallic chelate catalysts on a carbon substrate has been developed, with the objective of improving catalyst activity and stability for the reduction of oxygen in acidic electrolytes. Acetylene black carbon was chemically modified by bonding with polymerized iron tetrachlorophthalocyanine catalyst, followed by heat treatment. An electrode made with this catalyst showed significant improvement in activity and stability as compard with a similar unmodified catalytic electrode.     

Reaction between magnesium ammine complex compound and lithium hydride

The possibility of using ammonia as a hydrogen carrier is examined for the reaction between magnesium ammine complex MgCl₂(NH₃)₆ and lithium hydride LiH. Sample was milled at low temperature of −40 °C to avoid decomposition of MgCl₂(NH₃)₆ during the milling. The effects of milling time, milling speed (revolutions per minute), and catalysts on hydrogen storage properties were investigated by thermogravimetry, thermal desorption mass spectroscopy, and X-ray diffraction experiments. Experimental results indicated that a milled composite of Mg(NH₃)₆Cl₂ and catalyzed-LiH desorbed the ∼100% H₂ gas even at 125 °C in a closed system. The reverse reaction also proceeded by separately cooling MgCl₂ at lower temperature than 100 °C and heating LiNH₂ at 300 °C in the closed system.