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Masaki Nonaka

Publications and source records attributed to Masaki Nonaka.

3 recordsLinked to original sources
PubMed2003

Spectroscopic analysis of liquid/liquid interfaces in multiphase microflows.

Microscopic quasi-elastic laser scattering (muQELS) spectroscopy has been developed for analysis of interfacial phenomena at laminar multiphase microflow in a microchannel. Transport phenomena of a metal chelate through a water/toluene interface were measured, and transient adsorption of the chelate in the initial step of the transport was measured. A water/methanol miscible interface was also measured, and the interfacial free energy of a miscible interface was determined for the first time. The muQELS is expected to be very effective not only for physicochemical investigations of transport and mixing, but also for elemental process analysis of heterogeneous reactions.

Journal Article↗
PubMed2002

Stabilization of liquid interface and control of two-phase confluence and separation in glass microchips by utilizing octadecylsilane modification of microchannels.

We demonstrated a liquid/liquid and a gas/liquid two-phase crossing flow in glass microchips. A 250-microm-wide microchannel for aqueous-phase flow was fabricated on a top glass plate. Then, as a way to utilize the surface energy difference for stable phase confluence and separation, a 250-microm-wide microchannel for organic-phase (or gas-phase) flow was fabricated on a bottom glass plate and the wall was chemically modified by octadecylsilane (ODS) group. The top and bottom plates were sealed only by pressure. A microchannel pattern was designed so that the two phases made contact at the crossing point of the straight microchannels. The crossing point was observed with an optical microscope. Results showed that the ODS modification of the microchannel wall clearly improved stability of the interface between the two fluids. Pressure difference between fluids was measured and the interface of water and nitrobenzene was stable for the pressure difference from +300 Pa to -200 Pa. The pressure drop in a countercurrent flow configuration was also estimated, and the pressure difference required to realize the counter current flow was less than the allowable pressure range. Finally, we discussed the advantages of utilizing this approach.

Journal Article↗