IntroductionRecently, polyhexamethylene biguanide hydrochloride (PHMBHCl), a cationic polyelectrolyte, is widely used for disinfectants in personal-care products for cosmetics and toiletries, and for sanitizers in swimming pools. So far, many determination methods for polyelectrolytes, such as a poly(diallyldimethylammonium chloride) (Cat-floc), were developed by using conductometry, 1 turbidimetry, 2 potentiometry using ion-selective electrodes (ISEs), 3-21 colorimetric Toluidine Blue (TB) method, [22][23][24] fluorometry, 25-28 photometric titration method 29-31 and a voltammetric method. [32][33][34] However, only a few determination methods of PHMB-HCl have been reported. Hattori et al. 34 have reported an indirect determination of PHMB by using adsorptive voltammetry of 2-(5-bromo-2-pyridyl)azo-5-[N-npropyl-N-(3-sulfopropyl)amino]phenol on a carbon paste electrode.They also have examined several titrimetric determinations for PHMB-HCl: Kjeldahl method, non-aqueous titration, argentometric titration and colloidal titration. 35 Rowhani et al. 36 have developed a colorimetric assay determination using a complexation between Ni 2+ and PHMB in pool and spa water. Abad-Villar et al. 37 have demonstrated its capillary electrophoresis with contactless conductivity detection for the determination of PHMB-HCl in eye drops. However, each measurement range of PHMB-HCl concentration was above a few parts per million (ppm). Improvement of the sensitivity of the methods is required for determining a low concentration (∼1 ppm) in such contact-lens detergents. Among the determination methods of cationic polyelectrolytes, ISE method is expected to be an alternative to these methods for the determination of PHMB-HCl because the procedure of the ISE method can be easily performed and applied to colored samples and samples containing suspended solids.3-21 Masadome et al. 17,18 reported a potentiometric titration method of anionic polyelectrolytes such as poly(vinyl sulfate) (PVSK) by using a surfactant-selective electrode as an indicator electrode and a cationic polyelectrolyte, Cat-floc, solution as a titrant, where dodecylbenzene sulfonate (DBS) ion was added to a sample solution as an indicator ion. Just after the end-point of the titration, the concentration of free indicator ion decreases abruptly due to the ion association reaction between the indicator ion and the titrant. This decrease in the concentration of the indicator anion (DBS -) is detected as the potential jump of the surfactant-ISE and the end-point of the titration is determined.Hattori et al. 21 reported a potentiometric titration method for the determination of cationic polyelectrolytes using a surfactant-ISE developed by Masadome et al. [38][39][40][41][42] and TB cation as an indicator. The surfactant-ISE also responded to the TB cation. An end-point of the titration was detected as a sharp potential change due to an abrupt decrease in the indicator (TB) concentration caused by an ion association reaction between the TB ion and the titrant, PVSK. The...
A novel fiber optic localized plasmon resonance (FO-LPR) sensor composed of a D-shape optical fiber was proposed and demonstrated in the present study. The D-shape optical fiber was fabricated by a femtosecond laser micromachining system. The dimensions of the D-shape zone were 100 μm in depth measured from the surface of the polymer jacket layer, and the total length was 6 mm. After annealing treatment, the mean roughness of the surface was 231.7 nm as determined by AFM. The exposed surface of the D-shape fiber was modified with self-assembled gold nanoparticles to produce the FO-LPR sensor. The response of the sensor shows that the signal increases linearly with increasing refractive index. The sensor resolution of the sensor was determined to be 4.1×10 -4 RIU.
Due to high Fe4N chemical stability, wear resistance, and BS (saturation magnetic flux density), it shows promise as a magnetic recording medium. The many types of iron nitride, and their properties depend on their preparation. Iron nitrides were prepared by new PV D : electron shower. Nitriding increased with N 2 gas pressure, and the Fe 4 N single phase was obtained at PN z = 7 x 10-3 Torr. BS was high...... 1.1T , but H, (coercive force) low......300e. To increase H, due to shape anisotropy, Fe film was prepared by oblique evaporation, and nitrided by electron shower bombardment in PN2 = 0.01Torr for 420s. The iron film changed to iron nitride film (Fe 4 N + Fe2-3N), Bs was 0.75T and I-I, was 500Oe. Which made the film applicable in magnetic recording media.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.