Inactivation of Escherichia coli and Streptococcus mutans by ultrasound at 500 kHz

This paper shows a systematic study of the 500 kHz frequency ultrasound efficiency on the microbial inactivation as a function of ultrasonic power delivered into the bacterial suspension. The inactivation of Escherichia coli IAM 12058, a Gram-negative bacterium and Streptococcus mutans JCM 5175, a Gram-positive bacterium is enhanced by increasing the ultrasonic power in the range of 1.7–12.4 W and the logarithm of survival ratio decreases linearly with irradiation time, except for E. coli sonicated with the highest power level. The rate constants were estimated in the linear region of the plots representing survival ratio logarithm vs. sonication time. A better understanding of the inactivation process at 500 kHz could be gained by suppressing the chemical effects with a radical scavenger. We find out that the rate constants increase with the ultrasonic power delivered into the solution and dramatically decrease by the addition of t-butanol as a radical scavenger to the bacterial suspension. For comparison, experiments were carried out at a low frequency level of 20 kHz. It was found out that for the same ultrasonic power delivered into the bacterial suspension, the inactivation was slightly enhanced at 500 kHz frequency. The examinations of bacterium performed with a TEM revealed lethal damages arising from the interaction of bacterial cells with the cavitational bubbles. A significant amount of empty cell envelopes as well as their cytoplasmatic content was detected. Thus, based on these new data, the mechanism of bacterial inactivation by ultrasounds at high frequency is discussed here.     

Colored Turaev-Viro invariants of twist knots

In the present paper we give a formula for colored Turaev-Viro invariants of twist knots using special polyhedra derived from (1,1)-decomposition of the knots.     

Multiple Phase Transitions in CuO Studied by μSR

Precise measurements of the local magnetic field at muon sites in CuO were performed. The temperature dependence of the local field including spatial orientation was obtained in the ordered state. Not only zero field μSR measurements were performed, but also external magnetic fields were applied to obtain an unambiguous determination of field direction. Multiple stages of muon signals were observed at 55 and 80 K. An incommensurate phase between 212 K and 227 K was confirmed from the line shapes of the local fields at the muon sites. This revised version was published online in September 2006 with corrections to the Cover Date.     

Improvement of thermochromic property at low temperatures of CuMo0.94W0.06O4 by Zn substitution

Zinc-doped copper molybdenum oxide, Zn-doped CuMo_0.94W_0.06O₄, was synthesized, and the effects of the Zn doping on the thermochromic property of CuMo_0.94W_0.06O₄ were investigated at low temperatures. X-ray diffractometry and diffuse reflectance UV–Vis spectroscopy clarified that Zn doping for CuMo_0.94W_0.06O₄ promoted the structural phase transition of the γ-phase to the α-phase of CuMo_0.94W_0.06O₄ at low temperatures and Zn-doped CuMo_0.94W_0.06O₄ exhibited a drastic color change in the temperature range of 30–70 °C. Differential scanning calorimetry also confirmed that Zn doping changed the phase transition temperature of CuMo_0.94W_0.06O₄. Consequently, Cu_1?xZn_xMo_0.94W_0.06O₄ with x?=?0.01 exhibited a larger thermal change in the diffuse reflectance spectrum in the visible light range, compared with CuMo_0.94W_0.06O₄. An appropriate Zn-doping ratio was effective for enhancing the thermochromic property of the CuMo_0.94W_0.06O₄ pigment in the visible region in the temperature range of 30–70 °C.

     

Quantification of ultrasonic intensity based on the decomposition reaction of porphyrin

A simple method is proposed for quantification of the effective ultrasonic intensity in the reaction vessel based on the decomposition reaction of 5,10,15,20-tetrakis(4-sulfotophenyl) porphyrin (H₂TPPS⁴⁻). The change of concentration of porphyrin in solution irradiated by the ultrasound wave depends on the irradiation time and the output power of ultrasound generator. The decomposition ratio of porphyrin is defined as the ratio of the concentration of porphyrin after ultrasonic irradiation to that before ultrasonic irradiation. A linear relationship between the decomposition ratio of porphyrin and the concentration Fe³⁺ in the Fricke solution under sonication was obtained. The decomposition ratio was related to the absorption dose in radiation chemistry.     

A comparison of injection techniques using botulinum toxin injection for treatment of the spasmodic dysphonias

The benefit duration and side effects following effective treatment of spasmodic dysphonia or voice tremor using botulinum toxin injection were studied following 477 open trial unilateral or bilateral injections provided to 178 patients. A comparison of unilateral and bilateral injections in male and female patients with adductor spasmodic dysphonia demonstrated an increased benefit duration following unilateral injections in women, longer periods of breathiness in men than in women following bilateral or unilateral injections, and a trend for reduced benefit durations following repeated treatments using bilateral injections. Outcomes were similar in the adductor spasmodic dysphonia and vocal tremor groups following thyroarytenoid injection while benefit durations were reduced and side effects lasted longer in patients with abductor spasmodic dysphonia following cricothyroid injections. Long-term benefit > 1 year occurred in 12.3% of patients following injection.     

Scanning near-field optical images of ordered polystyrene particle layers in transmission and luminescence excitation modes

Scanning near-field optical images of hexagonally close-packed layers of polystyrene spherical particles with a diameter of 1.0 microm have been investigated. The layers were composed of particles that were doped either totally or partially with an organic fluorescent dye. Observations were made in the transmission and luminescence excitation modes with a scanning near-field optical microscope (SNOM) with a spatial resolution shorter than the wavelength of light. The patterns observed in the SNOM images are significantly dependent on the microstructures of layers, that is, the layers are either single or double layered, and the particles are either totally or partially doped. These results are discussed in terms of specific modes of electromagnetic waves transmitting across and along the layers after the local excitation at the tip end of the scanning microprobe.