Aerosol Generation Method for Measuring Particles Suspended in Water – Detection of Particulate Impurities in Ultrapure Water and Sizing of Fine Powders –

The method described is based on the fact that the measurement of particles in the gaseous phase is generally easier than that in the liquid phase for fine particles smaller than 1 μm in diameter. The system consists of a liquid nebulizing unit, evaporator, condenser, mixing diluter and two different aerosol sizing instruments. It has been found that this method can continuously detect particulate impurities in ultrapure water in situ and can measure the size distribution of fine powders in the submicron particle size range down to about 0.05 μm.     

Spherical neutron polarimetry studies on the magnetic structure of single crystal Cr1−xMoxB2 (x=0, 0.15)

By applying spherical neutron polarimetry technique to Cr_1−xMo_xB₂ (x=0, 0.15), we successfully determined its precise magnetic structures. We emphasize here that the ratio of magnetic component was determined by measuring the two satellite reflections and rotating the incident neutron spin directions.     

Bifurcation structure of chaotic attractor in switched dynamical systems with spike noise

High-frequency ripple (spike noise) effects in the qualitative properties of DC/DC converter circuits. This study investigates the bifurcation structure of a chaotic attractor in a switched dynamical system with spike noise. First, we introduce the system dynamics and derive the associated Poincaré map. Next, we show the bifurcation structure of the chaotic attractor in a system with spike noise. Finally, we investigate the dynamical effect of spike noise in the existence region of the chaotic attractor compare with that of a chaotic attractor in a system with ideal switching. The results suggest that spike noise enlarges an invariant set and generates a new bifurcation structure of the chaotic attractor.     

Precipitation of Zinc Sulfide Particles from Homogeneous Solutions

Zinc sulfide particles were homogeneously precipitated by thermal decomposition of thioacetamide in acidic aqueous solutions in a one-step process. The influence of the operating conditions (initial concentration of zinc ion and TAA) on the nucleation time and number concentration of the generated particles was investigated. The experimental results show that the model of homogeneous nucleation previously developed and successfully tested for silver particle generation by a chemical reduction method can also be applied to the formation of zinc sulfide particles by homogeneous precipitation. Furthermore, in the particle formation method in which the nucleation time t* can be measured, the particle number concentration n* can be predicted by the simple relation n*=1/(4pir*Dt*) (r* is the critical nucleus radius, and D the monomer diffusion coefficient). Thus the particle number concentration can be easily predicted even if the rate expression and the critical supersaturation concentration are unknown. Copyright 2000 Academic Press.     

Photo‐induced association behavior of poly(sodium acrylate) bearing a small amount of malachite green

The photo‐induced association and dissociation of poly(sodium acrylate) containing a small amount of photoresponsive malachite green (MG) in aqueous solution were studied. It is known that MG dissociates into ion pairs under UV irradiation to produce the green triphenylmethyl cation. The cation thermally recombines with its counter anion to regenerate the colorless neutral compound. The random copolymer of acrylic acid with 0.05 mol % of MG monomer [P(A/MG0.05)] was soluble in aqueous 0.01 M NaCl at pH 12 as a unimer due to electrostatic repulsion between carboxylate pendent groups when the MG moieties were in the neutral form. On the other hand, these MG groups were converted to the cationic form on UV irradiation, leading to polymer aggregation driven by electrostatic interactions between the cationic MG and anionic carboxylate pendent groups. These aggregates could be dissociated by heating in the dark, as the cationic MG reverted to its neutral form, eliminating these attractive electrostatic interactions. The association and dissociation of the copolymer was monitored by dynamic light scattering (DLS). When the salt concentration in aqueous solutions of P(A/MG0.05) was increased from 0.01 to 0.5 M at pH 12, no aggregation was observed on UV irradiation because of ionic screening of the aforementioned electrostatic interactions. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Development and micro-gap flow evaluation of electro-rheological nano-suspensions

Electro-rheological (ER) nano-suspensions based on titanium dioxide nano-particles with particle diameter on the order of 100 nm were prepared. Micro-gap flow behavior and microstructure were evaluated for the suspensions with a particle volume fraction of 8.8 vol%. For the nano-suspension based on a silicone oil, the ER effect and flow behavior were found to be stable during the sharing time on the order of 10²?s. The ER response measured at a given strength of the electric field for the nano-suspension based on a chemically modified silicone oil was effectively induced by the electric field, especially with low strengths, and it was larger than that of the nano-suspension based on the silicone oil but slightly lower than that based on a hydrocarbon oil. Furthermore, the relaxation of the ER response after removal of the electric field was somewhat slow for the nano-suspension based on the hydrocarbon oil, whereas it was fairly well for the nano-suspension based on the modified silicone oil.     

Visualization of dynamic change in contraction-induced lipid composition in mouse skeletal muscle by matrix-assisted laser desorption/ionization imaging mass spectrometry

Lipids in skeletal muscle play a fundamental role both in normal muscle metabolism and in disease states. Skeletal muscle lipid accumulation is associated with several chronic metabolic disorders, including obesity, insulin resistance, and type 2 diabetes. However, it is poorly understood whether the lipid composition of skeletal muscle changes by contraction, due to the complexity of lipid molecular species. In this study, we used matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) to investigate changes in skeletal muscle lipid composition induced by contraction. We successfully observed the reduction of diacylglycerol and triacylglycerol, which are generally associated with muscle contraction. Interestingly, we found the accumulation of some saturated and mono-unsaturated fatty acids and poly-unsaturated fatty acids containing phosphatidylcholine in contracted muscles. Moreover, the distributions of several types of lipid were changed by contraction. Our results show that changes in the lipid amount, lipid composition, and energy metabolic activity can be evaluated in each local spot of cells and tissues at the same time using MALDI-IMS. In conclusion, MALDI-IMS is a powerful tool for studying lipid changes associated with contractions.