Mesogenicity of testosterone and estrone derivatives

Mesogenicity of 3β, 17β-bis(4-n-alkoxybenzoyloxy) androstene homologues (BABA) (carbon No. of alkoxy group, n, = 1-10) were studied by use of D.S.C. and a polarized microscopy. It was found that the n = 4-10 compounds of BABA have one cholesteric mesophase with high thermal stability enantiotropically, and that the n = 1-3 compounds decompose just above the melting point. Mesogenicities of BABA and several testosterone and estrone derivatives were also discussed from the perspective of chemical structure and shape. The presence of an intramolecular long-range dipole coupling in two alkoxybenzoyloxy chromophores is found in BABA from CD spectral studies.     

A nonlinear least squares program, MULTI(FILT), based on fast inverse Laplace transform for microcomputers

A nonlinear curve fitting program MULTI(FILT) into which the fast inverse Laplace transform (FILT) is incorporated was developed on a microcomputer. FILT is an algorithm for the numerical inversion of Laplace-transformed equations (image equations) to generate the corresponding real time courses. The pharmacokinetic models can be defined in the form of Laplace-transformed equations as a subroutine in MULTI(FILT). MULTI(FILT) achieves the numerical inversion of the defined image equations according to FILT and the subsequent curve-fitting of the inverse-transformed time courses to the experimental data points to estimate the pharmacokinetic parameters by the nonlinear least-squares method. MULTI(FILT) has a function to impose constraints on the pharmacokinetic parameters. In order to verify the reliability of MULTI(FILT), the pharmacokinetic parameters estimated by MULTI(FILT) were compared with those by MULTI using 100 time courses which were artificially generated according to the Monte Carlo method, based on data for theophylline and bishydroxycoumarin. The estimated pharmacokinetic parameters by MULTI(FILT) agreed with those by MULTI. Thus, it is suggested that FILT, developed in the field of electronic technology, is also useful in the pharmacokinetic field.     

Raman characteristics of carbon nitride synthesized by nitrogen-ion-beam-assisted pulsed laser deposition

Raman characteristics of carbon nitride films synthesized by nitrogen-ion-beam-assisted pulsed laser deposition were investigated. In addition to the D (disorder) band and G (graphitic) band commonly observed in carbon nitride films, two Raman bands located at 1080–1100 and 1465–1480 cm^-1 were found from our carbon nitride films. These two bands were well matched with the predicted Raman frequencies for βC₃N₄ and the observed Raman bands reported for carbon nitride films, indicating their relation to carbon-nitrogen stretching vibrations. Furthermore, the relative intensity ratio of the two Raman bands to the D and G bands increased linearly with increasing nitrogen content of the carbon nitride films. Received: 30 October 2000 / Accepted: 5 February 2001 / Published online: 2 October 2001     

Top-gathering pillar array of hybrid organic–inorganic material by means of self-organization

Two-dimensional (2D) pillar arrays with submicrometer to micrometer repetitions have been fabricated from hybrid organic–inorganic material by mask lithography or multi-beam interference lithography. The type of array structure depends on structural parameters such as the pillar height, diameter and distance between neighboring pillars. Two kinds of periodic arrays, 2D arrays and ‘top-gathering’ arrays, can be obtained by controlling the structural parameters. In the top-gathering arrays, the pillars are gathered at the top by means of self-organization, and ‘top-gathering’ units composed of four pillars can be formed. PACS 68.35.Gy; 81.20.Fw; 82.50.-m     

A Triphenylamine with Two Phenoxy Radicals Having Unusual Bonding Patterns and a Closed‐Shell Electronic State

Reported herein is the structure and the electronic properties of a novel triphenylamine derivative having two phenoxy radicals appended to the amino nitrogen atom. X‐ray single crystal analysis and the magnetic resonance measurements demonstrates the unexpected closed‐shell electronic structure, even at room temperature, of the molecule and two unusual C? N bonds with multiple‐bond character. The theoretical calculations support the experimentally determined molecular geometry with the closed‐shell electronic structure, and predicted a small HOMO–LUMO gap originating from the nonbonding character of the HOMO. The optical and electrochemical measurements show that the molecule has a remarkably small HOMO–LUMO gap compared with its triphenylamine precursor.     

Palladium‐Catalyzed Direct C?H Arylation of Isoxazoles at the 5‐Position

A palladium‐catalyzed direct arylation of isoxazoles with aryl iodides has been achieved. The C H bond at the 5‐position is activated selectively to give coupling products in moderate to good yields. This direct arylation was applied to the synthesis of a spiro‐type chiral ligand, which proved to be most effective to the palladium‐catalyzed tandem cyclization of a dialkenyl alcohol.     

Fast and Robust Nanocellulose Width Estimation Using Turbidimetry

The dimensions of nanocelluloses are important factors in controlling their material properties. The present study reports a fast and robust method for estimating the widths of individual nanocellulose particles based on the turbidities of their water dispersions. Seven types of nanocellulose, including short and rigid cellulose nanocrystals and long and flexible cellulose nanofibers, are prepared via different processes. Their widths are calculated from the respective turbidity plots of their water dispersions, based on the theory of light scattering by thin and long particles. The turbidity‐derived widths of the seven nanocelluloses range from 2 to 10 nm, and show good correlations with the thicknesses of nanocellulose particles spread on flat mica surfaces determined using atomic force microscopy.

     

Effect of preparation process of microfibrillated cellulose-reinforced polypropylene upon dispersion and mechanical properties

Microfibrillated cellulose (MFC)-reinforced polypropylene (PP) was prepared via two engineering approaches: disintegration of the pulp by a bead mill followed by a melt-compounding process with PP (B-MFC-reinforced PP); and disintegration of the pulp mixed with PP by a twin screw extruder followed by a melt-compounding process (T-MFC-reinforced PP). The effects that the engineering process and the microfibrillation of the pulp had upon the dispersion and mechanical properties were investigated through tensile tests, rheological analysis and X-ray computed tomography. The bead-milling method enabled a uniform microfibrillation of the pulp to under 100 nm, which corresponded to a surface area of 133–146 m²/g for the pulp, found by the Brunauer–Emmett–Teller (BET) analysis. The T-MFC-reinforced PP with 30 wt% MFC content exhibited a tensile modulus of 5.3 GPa and a strength of 85 MPa, whereas the B-MFC-reinforced PP composites with the same content of MFC exhibited values of 4.1 GPa and 59.6 MPa, respectively. Rheological analysis revealed that the complex viscosity and storage modulus at 170 °C of T-MFC-reinforced PP with 30 wt% MFC content are 5–7 and 5–8 times higher than that of B-MFC-reinforced PP, respectively. This indicated that T-MFC was more dispersed in the PP than B-MFC. Therefore, T-MFC produced a more rigid interconnected network in the matrix during the melting state than B-MFC.     

Radiation in a hypersonic shock layer generated around a projectile

Radiation emitted from the shock layer generated around a hypersonic flight model is experimentally investigated by using a ballistic range (two-stage light-gas gun). A polyethylene projectile of 1.2 cm in diameter is launched in this facility at the velocity of 5 km/sec (M=15), and the emission from the induced shock layer around the projectile is observed with a spectroscope. As a result, molecular band-spectra from NO and N₂ are detected along with those from carboncontaining molecules. Total emission power is measured with a diode-type powermeter. In addition, dimension effect of the flight model is theoretically and numerically examined, and a scaling law on thermochemical structure of the shock layer is developed. It shows that the thickness of thermal boundary-layer formed on the model surface does not follow the conventional scaling law based on the reaction distance and on the energy relaxation distance. Finally, the radiative field around the projectile is numerically computed, and the total power emitted from the shock layer is estimated. From the comparison between computed and measured results, the validity of the calculation model is discussed.     

Mass,momentum and total excess energy transported by a weak planeN wave

A weakly nonlinear plane acoustic wave is emitted into an ideal gas of semi-infinite extent from an infinite plate by its sinusoidal motion of single period. The wave develops into anN wave in the far field, as long as the energy dissipation is negligible everywhere except for discontinuous shock fronts. The third-order effects at shock fronts are evaluated, i.e., the generation of reflected acoustic wave as a result of the interaction of shock and expansion wave and the production of entropy by the energy dissipation at shock fronts. Consideration of these effects enables one to estimate the whole mass, momentum and total excess energy (sum of the kinetic energy and excess of internal energy over an initial undisturbed value) transported by theN wave to the accuracy of third order of wave amplitude. It is shown that the mass and total excess energy transported by theN wave increase and the momentum decreases to asymptotic limits as the wave propagates. The result shows good agreement with a numerical result obtained by solving the Euler equations with a high-resolution TVD upwind scheme.