Polyaniline doped with dimethyl sulfate as a nucleophilic dopant and its electrochemical properties as an electrode in a lithium secondary battery and a redox supercapacitor

The physical properties of polyaniline (PAn) powder, doped by nucleophilic doping of dimethyl sulfate (DMS), were characterized, as well as its electrochemical behaviors, to investigate the possibility of a power source device adopting the PAn-DMS electrodes. It is shown that the nucleophilic addition of DMS into PAn concurrently resulted in an increase of the charge transport properties (e.g., electrical conductivity) and enhanced the processability (e.g., lowering of the melting point). The surface structure of PAn-DMS electrodes showed that the compactness of the electrode surface was helpful in increasing the capacity of lithium rechargeable batteries, whereas the porous behavior was valuable to improve the capacitance of a redox supercapacitor. Depending on the power source devices using the lump- and sheet-type PAn-DMS electrodes, the following optimized performances were obtained: more than 80 mA h g-1 after 50 cycles for lithium secondary battery use and approximately 115 F g-1 initially and approximately 94 F g-1 after 5000 cycles at a current density of 2.5 mA cm-2 for application as a redox supercapacitor, which were the highest reported performances for all PAn-based electrodes.     

Redox-induced conformational alteration of n,n-diarylamides

We constructed a novel molecular conformational alteration system with an N-aryl-N-phenylacetamide structure, in which the N-aryl group consists of a hydroquinone-p-quinone system as a redox-dependent aromatic trigger. The amide conformation depended on the oxidation state of the aryl group, and the two states (compounds 2 and 3) were reversibly converted to each other by redox reactions. Such compounds would be applied as useful structural units for external stimulus-responsive control on the shape and function of large molecules or supramolecules.     

Asymmetric synthesis of (+)-cis-nemorensic acid from a chiral Diels-Alder adduct of 2,5-dimethylfuran

(+)-cis-Nemorensic acid was synthesized from a chiral Diels-Alder adduct prepared by a catalytic enantioselective Diels-Alder reaction with 2,5-dimethylfuran and 2,2,2-trifluoroethyl acrylate.     

Highly selective ammonia synthesis from nitrate with photocatalytically generated hydrogen on CuPd/TiO2

Body-centered-cubic type CuPd nanoalloys were synthesized by a chemical reduction method. Photocatalytic hydrogen evolution and nitrate reduction were simultaneously examined over CuPd nanoalloys deposited on TiO(2) (CuPd/TiO(2)). The efficiency of hydrogen evolution over CuPd/TiO(2) was better than that over Pd/TiO(2). As for nitrate reduction, ammonia was selectively (78%) produced with hydrogen generated photocatalytically over CuPd/TiO(2). The continuous generation of nascent hydrogen atoms on the surface of the CuPd nanoalloy, where Cu and Pd are homogeneously mixed, led to the high selectivity for ammonia.     

Magnetic field anisotropy based MR tractography

Non-invasive measurements of structural orientation provide unique information regarding the connectivity and functionality of fiber materials. In the present study, we use a capillary model to demonstrate that the direction of fiber structure can be obtained from susceptibility-induced magnetic field anisotropy. The interference pattern between internal and external magnetic field gradients carries the signature of the underlying anisotropic structure and can be measured by MRI-based water diffusion measurements. Through both numerical simulation and experiments, we found that this technique can determine the capillary orientation within 3°. Therefore, susceptibility-induced magnetic field anisotropy may be useful for an alternative tractography method when diffusion anisotropy is small at higher magnetic field strength without the need to rotate the subject inside the scanner.     

Facile route to control the surface morphologies of 3D hierarchical MnO<Subscript>2</Subscript> and its Al self-doping phenomenon

In this article, a catalytic-ion assisted hydrothermal method has recently been developed for synthesis of hierarchical manganese dioxide nanostructures. In this study, various shapes of hierarchical MnO₂ (nanorod, nanothorn sphere, sphere) were successfully synthesized using the hydrothermal method with quantitative control of Al³⁺ in solution. The aspect ratio of aligned nanorods on the nanothorn sphere was easily controlled by the amount of Al³⁺ in the MnSO₄ and (NH₄)₂S₂O₈ aqueous solution. Furthermore, we found that Al³⁺ species in the solution acted as a functional doping species into 2 × 2 tunnels of α-MnO₂ and also as a catalyst. The formation mechanism of hierarchical MnO₂ structures as a function of Al³⁺ concentration during hydrothermal reaction was sufficiently investigated, and the role of Al³⁺ as catalyst and doping species in the solution was discussed.     

Size-dependent fracture of Si nanowire battery anodes

We use a unique transmission electron microscope (TEM) technique to show that Si nanowires (NWs) with diameters in the range of a few hundred nanometers can be fully lithiated and delithiated without fracture, in spite of the large volume changes that occur in this process. By analyzing the stresses associated with lithiation and delithiation we conclude that the process does not occur by the growth of discrete crystalline phases; rather it occurs by amorphization of the Si NWs followed by diffusion of Li into the structure. By accounting for the large deformation associated with this process and by including the effects of pressure gradients on the diffusion of Li, we show that Si NWs with diameters less than about 300 nm could not fracture even if pre-existing cracks were present in the NW. These predictions appear to be in good agreement with the experiment.     

Functionalization of methyl orange using cationic peptide amphiphile: colorimetric discrimination between ATP and ADP at pH 2.0

A solvatochromic and non-fluorescent acid-base indicator, methyl orange (MO) was applied to colorimetric discrimination between adenosine triphosphate (ATP) and the corresponding diphosphate (ADP) at pH 2.0 in the presence of L-glutamic acid-derived cationic peptide amphiphile 1. This method is based on the fact that the amphiphile 1 can prevent MO from protonation even at pH 2.0. No similar colour change was observed when ADP was added instead of ATP under the same conditions. The effect of the molecular structure of several peptide amphiphiles and dyes was also investigated.     

Gradient estimates for higher order elliptic equations on nonsmooth domains

We establish optimal gradient estimates in Orlicz space for a nonhomogeneous elliptic equation of higher order with discontinuous coefficients on a nonsmooth domain. Our assumption is that for each point and for each sufficiently small scale the coefficients have small mean oscillation and the boundary of the domain is sufficiently close to a hyperplane. As a consequence we prove the classical Wm,p, m=1,2,…, 1<p<∞, estimates for such a higher order equation. Our results easily extend to higher order elliptic and parabolic systems.