Heat capacity and phase transition of a five-coordinated antiferromagnet,IODOBIS (N,N-diethyldithiocarbamato) iron (III), in the temperature range from 0.4 TO 300 K

The heat capacity of iodobis (N,N-diethyldithiocarbamato) iron (III) has been measured between 0.4 and 300 K. A phase transition from an antiferromagnetic to a paramagnetic state was found at T_N = (1.937 ± 0.010) K, and a Schottky-type anomaly arising from a zero-field single ion splitting was observed around 12 K. The total magnetic entropy and enthalpy, including the phase transition and the Schottky-type anomaly, are 11.36JK^?1mol^?1 and 134.5 J mol^?1, respectively. The entropy is approximately equal to Rln 4 ( = 11.53 JK^?1mol^?1), confirming that the spin manifold is really a quartet. The entropy and enthalpy due to the phase transition are estimated to be (5.57±0.01)JK^?1mol^?1 and (13.2±0.05)Jmol^?1, respectively. The entropy and enthalpy above t_n are quite large, as in the case of the related compound chlorobis (N,N-diethyldithiocarbamato) iron (III). This fact suggests that the present complex may be considered to have a two-dimensional type of magnetic structure from a thermodynamic point of view. A correlation diagram between the transition entropy and energy is proposed, this being a diagnostic for the determination of the magnetic dimensionality.     

Transfer of exogenous macromolecules from rat stomach wall to blood and lymph is dependent on molecular weight.

Transfer selectivity to the blood and the lymph of exogenous dextrans of various average molecular weight (approximate 4, 10, 18, 39 and 70 kilodaltons (kDa)) after dosing to the subserosal layer of the rat stomach wall was investigated by measuring the fluorescein isothiocyanate labelled dextran concentrations in the lymph of the thoracic duct and the peripheral plasma. The lymph/plasma level ratio of the dextrans rose greatly with the increase in molecular weight (over 10kDa) owing largely to the lower plasma concentration, although the lymph levels of small dextran (4kDa) were not significantly higher than the plasma levels. These results indicate that there is an inverse relation between plasma levels of dextrans and their molecular weight, and also suggest that the molecular weight threshold of transfer selectivity of dextran to the blood and the lymph administered in the rat stomach wall is between 4-10 kDa.     

Use of an adjustable soft segment as an effective molecular design for crystal engineering of hydrogen-bonded tape motifs

From all the 11 alkylsilylated guanosine and adenosine derivatives having different numbers and types of nonpolar and flexible alkylsilyl side chains, 13 crystals were obtained from appropriate solvents in spite of their low molecular symmetry, and their crystal structures were studied by X-ray crystallography and thermal analysis. In these crystals, a clear structural hierarchy was observed, and one-dimensional tape motifs were preferentially formed by multiple inter-base hydrogen bonds. The tape motifs were arranged in lamellar-like (L), herringbone (H) or widened lamella (WL) structures in the crystals. However, the alkylsilylated ribose unit adopted a variety of conformations with notable disorders at the alkylsilyl moiety. These results suggested that role of the adjustable and nonpolar alkylsilyl ribose unit was to provide cushioning or a filling effect as a molecular pad, which assisted the crystal packing of the robust tape motifs. The packing mode of the tape motifs could be understood from the size instead of the shape of the adjustable alkylsilyl ribose moiety, offering a novel approach to their crystal engineering.     

Analog Integrated Circuit for Motion Detection against Moving Background Based on the Insect Visual System

A network for displaying the velocity signal of a target edge which has larger velocity than the background was proposed and designed based on an insect visual system. In the insect visual system, the velocity signals generated by the background are inhibited by the signals generated by averaging the velocity signals from each cell and can only display the velocity signals of the target. The proposed network was constructed with simple analog circuits. The measured results of the test chip fabricated with the 1.2$mUm complementary metal-oxide-semiconductor (CMOS) process showed that the edge detection circuit inserted to the first stage of the proposed network can detect the edge position. It was apparent from the measured results of the test circuit constructed with discrete metal-oxide-semiconductor (MOS) transistors that the proposed unit circuit constructing the network can generate the velocity signals by inputting the edge signals. The results with the simulation program with integrated circuit emphasis (SPICE) showed that the proposed network can only display the velocity signals of the target edges but not those of the background. Thus, it was clarified that the various motion directions of the target can be detected independent of the background by using the proposed network.     

On Modular Standard Modules of Association Schemes

We will determine the structure of the modular standard modules of association schemes of class two. In the process, we will give the theoretical interpretation for the p-rank theory for strongly regular graphs, and understand the p-rank as the dimension of a submodule of the modular standard module. Considering the modular standard module, we can obtain the detailed classification more than the p-rank and the parameters.     

Different pathways in mechanical unfolding/folding cycle of a single semiflexible polymer

Kinetics of conformational change of a semiflexible polymer under mechanical external field were investigated with Langevin dynamics simulations. It is found that a semiflexible polymer exhibits large hysteresis in mechanical folding/unfolding cycle even with a slow operation, whereas in a flexible polymer, the hysteresis almost disappears at a sufficiently slow operation. This suggests that the essential features of the structural transition of a semiflexible polymer should be interpreted at least on a two-dimensional phase space. The appearance of such large hysteresis is discussed in relation to different pathways in the loading and unloading processes. By using a minimal two-variable model, the hysteresis loop is described in terms of different pathways on the transition between two stable states.