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The use of chlorine for disinfection dates back to 1847, when Semmelweis ordered hand-washing with chlorinated water before deliveries. 1 It was later realized that aqueous chlorine solution is highly effective in preventing streptococcal infection. In recent years it has become a common practice to use acidic electrolyzed water (acidic EW) prepared by the electrolysis of an aqueous NaCl solution for disinfection. Acidic EW has strong bactericidal activity, and has been used in medical applications, such as in the prevention of methicillin resistant Staphylococcus aureus (MRSA) infections. It has also become useful in the food and agricultural industry. It has recently been established in our laboratory that in the case of Escherichia coli (E. coli) K12 and Bacillus subtilis PCI219, the bactericidal activity of acidic EW was virtually identical to that of a hypochlorous acid solution at the same pH value. 2 We thus concluded that the bactericidal activity of acidic EW is correlated with the concentration of hypochlorous acid.Chlorine species that exist in aqueous medium and are available for disinfection are generally called available chlorine for disinfection. It is known that in aqueous media chlorine exists in three different chemical species, i.e., Cl2, HClO, ClO -, depending upon the pH. The concentration of the unreacted mixture of Cl2, HClO and ClO -is called free available chlorine. It has, however, been known that the bactericidal activity of free available chlorine is strongly influenced by the concentration of non-specific reducing agents that coexist in the medium. This indicates that we must be careful in quantitating the effective concentration of free available chlorine in the medium in order to achieve the maximum effect of acidic EW for disinfection.Free available chlorine, as determined around neutral pH, is known to be depleted through oxidation-reduction reactions with a variety of inorganic and organic materials. 3 Furthermore, it can react with ammonia and amino acids to form N-chloro compounds. The total amount of this form of reacted chlorine is generally termed combined available chlorine.3 Combined available chlorine is much lower in bactericidal activity than the free form. [3][4][5][6] In the present report we show that the concentration of free available chlorine is influenced by the presence of reducing agents in order to characterize the optimal condition for disinfection by acidic EW. Three methods are commonly used for quantitating the available chlorine concentration in aqueous media: iodometric titration, the o-tolidine method and the N,Ndiethyl-p-phenylenediamine (DPD) method. The iodometric titration method is unable to distinguish free available chlorine from combined available chlorine. The o-tolidine method can distinguish these two forms, but only with poor accuracy. The DPD method is the most selective method for assaying these two forms. This method is based on the oxidation of an indicator (DPD) to colored species. In the absence of iodide ion, free available chlorine ...

ABSTRACT:We developed a trapped-field magnet system using a bulk high-temperature superconducting (HTS) material (Sm-Ba-Cu-O; abbreviated as Sm123) and used it to observe a signal of 1 H nuclear magnetic resonance (NMR). The compact magnet system can fit on a table and needs no conventional refrigerant such as liquid helium. The magnet has a c-axis-oriented single-domain Sm123 bulk superconductor containing 20 wt.% Ag and was synthesized in the melt-textured process. The magnet is constructed of two cylindrical pieces, 36-mm outer and 7-mm inner diameters, respectively, and 16-mm thickness. This configuration results in magnetic field stability and suitable homogeneity for observation of NMR signal. The magnet was magnetized to 3 T by an ordinary NMR superconducting magnet by using a field cooling (FC) method. The bulk magnet was magnetized at 60K and has been kept at the temperature under 58K by using a pulse tube refrigerator. We observed 1 H NMR signal from the silicon rubber with the size of 1.2 mm diameter and 1.5 mm length at 2.89 Tesla (123 MHz) and 228 kHz peak width.

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The present paper reports on the results of a series of authors’ parabolic flight experiments on spray cooling in addition to ground-based experiments in which the influence of heater orientation and the behavior of rebounded droplets were especially studied in detail. Water and FC-72 (perfluorocarbon) were employed alternatively as a test liquid sprayed from a single full-cone nozzle onto a Cr-plated surface of an electrically heated copper block for transient cooling experiments or onto a transparent ITO (indium tin oxide) coated surface of a glass block for steady state experiments in a relatively low superheat region. Each experimental run was accomplished within some 15 sec through which a stable reduced gravity condition (0.01 times the terrestrial gravity) was maintained in the aircraft. Cooling curves were obtained over a wide range of each of the following parameters: the wall superheat, the spray volume flux and the Weber number for the spray droplets. It is demonstrated that the gravity dependency of the spray cooling characteristics varies with the spray volume flux and the droplet Weber number. Qualitative interpretations of the observed gravity dependency are provided.