Takashi Nakagawa

Highly efficient synthesis of propargyl- and allenyltitanium reagents from propargyl halides or propargyl alcohol derivatives. Practical synthesis of allenyl and homopropargyl alcohols

Abstract Reaction of Ti(O-i-Pr) 4 /2 i-PrMgBr, synthetic equivalent of practical Ti(II) reagent, with propargyl halides or propargyl alcohol derivatives affords allenyl titanium compounds in excellent yields, thus providing an efficient and practical method for synthesis of both allenyl and homopropargyl alcohols by the successive treatment with aldehydes or ketones.

Experimental results and model for the permeability of sprayed NiZn ferrite films

The high-frequency permeabilities of several NiZn ferrite films prepared by spray plating were investigated up to 6GHz. An adaptation of the Bouchaud–Zerah effective medium model provided an analytical expression for the microwave permeability, with a simple dependence on the magnetization distribution. An excellent agreement with the experimental results was obtained, in the demagnetized state as well as in the remnant state.The high-frequency permeabilities of several NiZn ferrite films prepared by spray plating were investigated up to 6GHz. An adaptation of the Bouchaud–Zerah effective medium model provided an analytical expression for the microwave permeability, with a simple dependence on the magnetization distribution. An excellent agreement with the experimental results was obtained, in the demagnetized state as well as in the remnant state.

Coupling of MnZn-ferrite films onto electronic components by a novel solution process for high frequency applications

A novel approach for the preparation of “coupling-type noise suppressors” in which ferrite films are directly deposited onto the components of the printed circuit board is reported. Crystalline MnxZnyFe3−x−yO4 films were fabricated on IC chips and polyimide substrates by a soft-chemistry route at temperatures below 100 °C. A “reaction-solution” comprising MCl2 (M = Mn, Zn, Fe) and an “oxidizing-solution” (pH buffer + oxidizing agent) were sprayed simultaneously onto a substrate maintained at 90 °C on a rotating disk. The as-prepared films were highly crystalline and hence do not require any post annealing. The magnetic and electrical properties of the films were studied. The films exhibited a large magnetic loss (imaginary permeability µ″) in GHz range and also exhibited high resistivity in accordance to overcome the heat treatment during the reflow soldering process. Resistivity of 2 × 105 Ω sq−1 was found to be the lower limit for the coupling-type noise suppressors. Noise suppression of above 50% at 10 GHz was obtained for a 6.7 µm thick MnZn-ferrite film and was equivalent to that of commercialized composite sheet noise suppressors of 50 µm thickness.

Synthesis and pharmacological activities of 13-Dehydro derivatives of primary prostaglandins

13-Dehydro derivatives of prostaglandin E1, E2, E3, F1 alpha and F2 alpha were synthesized. Compared with natural prostaglandins, 13-dehydro analogues were found to exhibit more potent inhibitory activity against human platelet aggregation and relaxation of guinea-pig isolated trachea, while they showed less potent activity of contraction of guinea-pig isolated ileum.

Quantitative Methods for Testing Antiviral Activities of Textile Fabrics

Objective: In recent years, antiviral products modified with various antiviral agents are now widely studied and developed. The establishment of appropriate antiviral testing methods for such products is necessary to discuss the efficiency of antiviral agents in the products. In this study, quantitative antiviral testing methods for textile fabrics were studied under several test conditions. nMethod: Influenza virus and feline calicivirus were used as model viruses. A cotton fabric and a 100% polyester fabric were used as control samples and Ag nanoparticles were used as model antiviral agents. In testing the antiviral performance of a product with an antiviral treatment, a virus suspension is inoculated onto the product and subsequently washed out of the products. The virus infectivity titer in the washed-out suspension is then measured. The viral infectivity titer of the test suspension was determined by counting the plaque-forming units (PFU). In estimating the antiviral activity of textile products, the components of the virus suspension, the contact time, and the contact temperature were chosen as study points. nResults: The virus infectivity titer was significantly affected by experimental conditions such as the concentration of the medium of the virus suspension, the contact temperature, and the type of textile fabric support. To estimate the antiviral efficiency under stable conditions for viruses, a lower temperature and a lower Eagle’s minimal essential medium (EMEM) concentration appear to be appropriate. It was confirmed that Ag nanoparticles on textile fabrics have antiviral activity; however, this antiviral activity was suppressed in media of high concentrations. nConclusions: It was shown that inactivation of antiviral agent might be caused by components of the virus suspension, as well as by other experimental conditions. Furthermore, the viruses can be deactivated by contact with textile fabrics, even in the absence of antiviral agents. These findings indicate that the antiviral performance testing conditions must be carefully chosen with due consideration of the field of application.