Effect of 1.5 T steady magnetic field on neuroconduction of a bullfrog sciatic nerve in a partially active state within several hours after extraction.

The bullfrog sciatic nerve within six hours after extraction was determined from the change with time in the action potential and the impedance to be a partially active nerve. Steady magnetic fields have been determined to be ineffective in the neuroconduction in the fresh nerve just after extraction. Although ion motions involved in the neuroconduction in the partially active nerve are not normal, it was confirmed that a 1.5 T steady magnetic field is ineffective in the neuroconduction in the partially active nerve. The obtained results suggest that the neuroconduction in damaged nerves is not affected by the 1.5 T steady magnetic field used in MRI.     

Synthesis and properties of TSF-based spin-polarized donor

A novel organic donor radical, TSBN, which is a benzotetraselenafulvalene derivative carrying a nitronyl nitroxide group in a cross-conjugated manner was prepared. X-ray crystallographic analysis revealed that TSBN forms a sheet-like network within the ac plane through intermolecular chalcogen contacts. Its spin-polarized structure was confirmed by cyclic voltammogram, ESR spectra of singly oxidized species and DFT calculation. The neutral crystal of TSBN showed nonlinear I–V characteristics at 2 K and exhibited negative magnetoresistance (?5% at 2 K under 5 T).     

(P)-helicene displays chiral selection in binding to Z-DNA

Enantiomeric helicenes of (P)-A and (M)-A were synthesized. The binding of the helicenes to B- and Z-DNA was studied quantitatively by CD, equilibrium dialysis, and fluorescence spectroscopy. Enantiomeric (P)-A not only bound selectively to Z-DNA but also effectively converted the B-DNA conformation to Z-DNA. The enantioselectivity of the helicenes offers a new route for the rational design of inhibitors of biological functions that may depend on Z-DNA.     

Magnetic resonance imaging of molecular transport in living morning glory stems

MRI was applied to investigate the transport pathways in Morning Glory plant stems. The study was carried out on living plants without affecting their integrity. The architecture of a dicotyledonous plant was deeply characterized: the root system structure and the vascular bundle location were identified, the presence of central voids caused by cell maturation and loss were observed in the stem. Molecular transport components were recognized, by observing the concentration profile of a tracer, which changed with time after its absorption by the plant roots. MRI analysis revealed the presence of an axial transport as the progress of the tracer front through the vascular bundles and a radial molecular transport from the vascular bundles toward the surface of the stem. As a result, the tracer molecular transport formed the parabolic tracer front (PTF). A model was built up through the analysis of the PTF that consisted of an axial front at the peak position and a radial front at the width of the parabolic tail. PTF analysis revealed differences between the tracer transport velocities in the axial and the radial directions in the plant stem. The model revealed that the width of the parabolic tail reflected the magnitudes of diffusion and permeation of the tracer in the plant stem.     

Many different covering numbers of Yorioka’s ideals

For ${b \in {^{\omega}}{\omega}}$ , let ${\mathfrak{c}^{\exists}_{b, 1}}$ be the minimal number of functions (or slaloms with width 1) to catch every functions below b in infinitely many positions. In this paper, by using the technique of forcing, we construct a generic model in which there are many coefficients ${\mathfrak{c}^{\exists}_{{b_\alpha}, 1}}$ with pairwise different values. In particular, under the assumption that a weakly inaccessible cardinal exists, we can construct a generic model in which there are continuum many coefficients ${\mathfrak{c}^{\exists}_{{b_\alpha}, 1}}$ with pairwise different values. In conjunction with these results, we give a generic model in which there are many Yorioka’s ideals ${\mathcal{I}_{f_\alpha}}$ with pairwise different covering numbers.     

On the velocity of sound in an itinerant-electron antiferromagnet

The longitudinal sound velocity in an itinerant-electron antiferromagnet is studied, using a jellium model for the ions and a two-sub-band model for the itinerant electrons with an energy gap caused by the antiferromagnetic spin ordering. It is shown that the longitudinal sound velocity decreases with decreasing temperature, due to the electron-photon interaction. The exchange interaction between itinerant electrons is seen to play a particularly important role in the phonon softening phenomena for such a system; and although the model is a great simplification of reality it gives reason to believe that the observed elastic anomalies in the face-centred-cubic 3d transition metal alloys are directly related to their tendency towards antiferromagnetism.     

Diastereomeric difference of inclusion modes between (-)-epicatechin gallate, (-)-epigallocatechin gallate and (+)-gallocatechin gallate, with beta-cyclodextrin in aqueous solvent

Inclusion complexes of (-)-epicatechin gallate (ECg) as well as (+)-gallocatechin gallate (GCg) and beta-cyclodextrin (beta-CD) in an aqueous solution were investigated using several NMR techniques and a computational method. ECg and EGCg formed a 1:1 complex with beta-CD, in which the A ring and a portion of the C ring were included from the wide secondary hydroxyl group side of the beta-CD cavity, and the B and B' rings were left outside the cavity. GCg formed a 1:2 complex with beta-CD, in which the A and B rings of GCg were included by two molecules of beta-CD. The difference between the two modes of inclusion of the 1:1 complex of ECg, EGCg.beta-CD and the 1:2 complex of GCg.beta-CD might have resulted from the size of the space between the B and B' rings in aqueous solution. As a result of nuclear Overhauser effect (NOE) experiments, GCg was considered to have a large enough space between the B and B' rings to include the B ring in the beta-CD cavity; on the other hand, ECg and EGCg have no such large space.     

Lipophilicity measurement of drugs by reversed phase HPLC over Wide pH range using an alkaline-resistant silica-based stationary phase, XBridge Shield RP(18)

We propose a reversed phase HPLC (RP-HPLC) with an alkaline-resistant silica-based stationary phase, XBridge Shield RP(18), for the determination of the lipophilicity of drugs with diverse chemical nature ranging from acidic to basic. A set of 40 model compounds with well-defined solvatochromic parameters was selected to allow a broad distribution of structural properties. The chromatographic results showed that the lipophilicity index log k(w) obtained with XBridge Shield RP(18) was well correlated with experimental log P(oct) values (r(2)=0.96). Linear solvation free-energy relationship (LSER) analyses revealed that the retention mechanism of the stationary phase and 1-octanol/water partitioning were controlled by almost the same balance of intermolecular forces (hydrophobicity as expressed by the van der Waals volume V(w), H-bond acceptor basicity beta, and dipolarity/polarizability pi*). The results showed that XBridge Shield RP(18) phase overcomes the shortcomings of the silica-based stationary phases, the application of which to lipophilicity measurements had been limited to neutral and acidic compounds.