Development of a Millimeter Wave Compact Equipment for NDT of Materials

We developed a compact equipment working at 94 GHz to replace the commonly used network analyzer for nondestructive testing of materials. The compact equipment was designed to measure the variations in the amplitude and phase of the reflected signal from the material relative to a reference signal. A good accuracy of the amplitude and phase measurement of the equipment was obtained in the confirmative experiments. The distribution of a drop of water in a wood plate is clearly visible in the millimeter wave images obtained by the amplitude and phase measurement.     

Syntheses and antitumor activities of N6,N6-dimethyladenosine carboxylate analogues

Several analogues substituted with fatty acid at the 2'-, 3'-, or 5'-position of the ribose moiety of N6,N6-dimethyladenosine were synthesized and tested for antitumor activity against cultured cells of L1210 leukemia and/or Ehrlich ascites. The cytotoxicity and increase of life span obtained with congeners in the N6,N6-dimethyladenosine 3'- or 5'-substituted series were comparable to in vitro or several times better in vivo than those of the mother compound.     

Spectrophotometric determination of traces of hydrogen peroxide with the Ti(IV)-xylenol orange and the Ti(IV)-chromazurol S reagents

The formation of mixed ligand complexes in Ti(IV)-xylenol orange (XO)-H₂O₂ and Ti(IV)-chromazurol S (CAS)-H₂O₂ systems was studied by spectrophotometry. The former system gave constant absorbance (λ_max = 562 nm) under the condition of [XO]/[Ti(IV)] = 1 in the pH 2–4 region. In the latter system, a distinct maximum at 557 nm was observed when [CAS]/[Ti(IV)] = 4 in the pH range of 4.5–5.2. In both cases, the absorbance at λ_max was stable for a long time and proportional to the concentration of hydrogen peroxide. From those facts, the usefulness of the mixtures of Ti(IV)-XO and Ti(IV)-CAS as the colorimetric reagents for the determination of hydrogen peroxide can be expected. The conditions for the use of the Ti(IV)-XO and the Ti(IV)-CAS reagents were examined in detail, and both reagents were found to be available for trace analysis of hydrogen peroxide with high sensitivity.     

Effect of equimolar salt to decyltrimethylammonium decyl sulfate on vesicle formation and surface adsorption

The aqueous solution of mixture of sodium decyl sulfate (SDeS) and decyltrimethylammonium bromide (DeTAB) has been found to form equilibrium multilamellar vesicles (MLV) spontaneously. We measured the surface tension of the aqueous solution of 1:1 mixture of SDeS and DeTAB as a function of temperature T at various molalities m under atmospheric pressure. The surface density, the entropy of adsorption and the entropy of vesicle formation are evaluated and compared with those of the decyltrimethylammonium decyl sulfate (DeTADeS) aqueous solution system to investigate the role of small counterions in the mechanism of equilibrium vesicle formation. The saturated surface density Gamma (H,C ) vs T curve of the SDeS/DeTAB system sits below that of the DeTADeS system. Therefore, sodium and bromide ions are negatively adsorbed and nevertheless, they neutralize the electric charge of the decyl sulfate ion DeS(-) and the decyltrimethylammonium ion DeTA(+) to some extent to weaken the electrostatic attraction between the polar head groups in the adsorbed film. The net surfactant concentration required for vesicle formation was larger in the SDeS/DeTAB system. Hence, the electrostatic attraction between the polar head groups of the surfactant ions which is one of the major driving forces for vesicle formation is weakened by the presence of the counterions Na(+) and Br(-). Small but distinct changes in the surface density and the entropies of MLV formation of the SDeS/DeTAB system from those of the DeTADeS system were also found.     

Hexanuclear Pt complexes composed of two cyclic triplatinum units connected with 1,4-diphenylene and 1,1′-ferrocenylene spacer

1,4-Bis(dimethylsilyl)benzene reacted with [Pt₃H(PEt₃)₃(μ-PPh₂)₃] at room temperature to yield trinuclear Pt complex [Pt₃(SiMe₂C₆H₄SiMe₂H)(PEt₃)₂(μ-PPh₂)₃] (1a). Heating a solution containing an equimolar mixture of [Pt₃H(PEt₃)₃(μ-PPh₂)₃] and 1a at 60 °C produced a hexanuclear Pt complex [(PEt₃)₂(μ-PPh₂)₃Pt₃(SiMe₂C₆H₄SiMe₂)Pt₃(PEt₃)₂(μ-PPh₂)₃] (2a). Complex 1a was characterized by X-ray crystallography and NMR spectroscopy, while the structure of 2a was determined by X-ray crystallography of single crystals containing 2a and [Pt₃H₂(PEt₃)₂(μ-PPh₂)₄] in 1:1 ratio. [Pt₃(SiMe₂fcSiMe₂H)(PEt₃)₂(μ-PPh₂)₃] (fc = Fe(η⁵-C₅H₄)₂) (1b) and [(PEt₃)₂(μ-PPh₂)₃Pt₃(SiMe₂fcSiMe₂)Pt₃(PEt₃)₂(μ-PPh₂)₃] (2b) were obtained similarly from the reactions of 1,1′-bis(dimethylsilyl)ferrocene with [Pt₃H(PEt₃)₃(μ-PPh₂)₃] and characterized by NMR spectroscopy and elemental analyses.     

Factors affecting physicochemical properties of liposomes prepared with hydrogenated purified egg yolk lecithins by the microencapsulation vesicle method

We examined hydrogenated purified egg yolk lecithins, having practical advantages over non-hydrogenated ones, as liposomal membrane materials. Liposomes were prepared by the microencapsulation vesicle (MCV) method in which liposomes are formed through two-step emulsification and dispersion. Three types of purified egg yolk lecithins with different iodine values were examined after being dissolved in one of three lipid solvents. The liposome size increased as the temperature during the second emulsification increased, being closer to the boiling temperature of the solvent. The preparation temperature in relation to the transition temperature of each lecithin was also a factor affecting liposome sizes. As for the encapsulation efficiencies of the model compound calcein in liposomes, they differed mainly depending on the solubility of each lecithin in a lipid solvent and it was more obvious in hydrogenated lecithins. A high preparation temperature resulted in lower encapsulation efficiencies, suggesting that leakage of encapsulated calcein was facilitated at high temperature in the MCV methods. There was a significant correlation between liposome sizes and encapsulation efficiencies in non-hydrogenated purified egg yolk lecithin but not in hydrogenated ones. When using hydrogenated purified egg yolk lecithins as liposomal membrane materials, it was suggested that a lipid solvent should be chosen so that a lecithin completely dissolves under the preparation condition in order to achieve a higher encapsulation efficiency. Smaller liposome particles were obtained when the second emulsification was performed at a lower temperature compared with the boiling point of the lipid solvent. These findings can be applied to control encapsulation efficiencies and particle sizes in each particular liposome preparation enclosing therapeutic agents.     

Synthesis of diazepinoquinoxalines and imidazolobenzopteridines

Diazepinoquinoxalines 3, 4 and imidazolobenzopteridines 5, 6a-d, 7a-d, 8, 9 were synthesized from 3-allylamino-6,7-dimethyl-2-quinoxalinecarboxamide ( 1 ) and 2-allylamino-6,7-dimethyl-3,4-dihydrobenzo[g]pteridin-4-one ( 2 ) by the intramolecular cyclization using phenylselenenyl chloride.