The design, fabrication and use of mesh microcontactor structures is described. These allow contact between immiscible fluid phases (liquid/liquid or gas/liquid) enabling mass transfer and reaction between and within the phases. The phases are not mixed and are removed separately for subsequent use or analysis. The structures were designed for kinetic studies on biphasic reactions with the ability to handle sequential samples without excessive sample dispersion. Mass transport conditions are defined by fluid layer depths of 100 microm and the volume for each phase contacting in the reaction region was selected at 100 microl as sufficient for a range of analytical techniques. Micromeshes with pore diameter, depth, and spacing each of approximately 5 microm were formed by electrodeposition of nickel onto substrates with defined photoresist layers, and released by etching a copper sub-layer. Reactor enclosures defining chambers on each side of the mesh were formed from milled glass and metal components. The assembled structures have been used in flow-through and static fluid modes. System function has been demonstrated for both liquid/liquid and gas/liquid reactions. Test chemistries selected for ease of optical monitoring were hydrolysis of colourless fluorescein diacetate in toluene with transfer as fluorescein anion to aqueous alkali, and oxygen absorption into aqueous alkaline pyrogallol solution generating a coloured product, purpurogallin.
A microstructured mesh contactor that can offer residence time of more than minutes is used for gas-liquid-solid hydrogenations and gas-liquid asymmetric hydrogenations. Applications for catalyst/chiral inductor screening and for kinetic data acquisition are demonstrated.
Analytical design studies, simulation, and a series of wind tunnel tests have led to the demonstration of a closed-loop vibration suppression system in the Baeing Vertol V/STOL Wlnd Tunnel. Using small amounts of oscillatory swashplate molion, this active ronlrol system simullsneously suppressed up to 90 percent of the fourper-rev vertical force, pitching moment, and rolling moment of a 3.05 m (10 fool)-diameter, four-bladed hingeless rotor. The system operated successfully in a large number of flight coaditions including trsnsition and autorotation. Response time to cancel sudden changes of vibration level was very short, about 1.25 rotor revolutions. Thus the system will be able to suppress vibration of a flight vehicle during maneuvers and gusty conditions. The system, although demonstrated on a hingeless rotor, is also applicable to arlieulated single and tandem rotor configurations. The wind tunnel testing included measurement of rotor fatigue loads, control loads, and performance. Based on the data, active control appears to be a practical approach to vibration suppression. The technology is now ready for full scale development.
A fire experiment conducted in a British 1950s-style house is described. Measurements of temperature, smoke, CO, CO2 , and O2 were taken in the Lounge, stairwell, and front and back bedrooms. The front bedroom door was wedged open, while the door to the back bedroom was wedged closed. Contrary to expectations and despite the relatively small fire load, analysis and hazard calculations show permeation of toxic fire gases throughout the property with lethal concentrations of effluent being measured at each sampling point. A generally poor state of repair and missing carpets in the upper story contributed to a high degree of gas and smoke permeation. The available egress time was calculated as the time before the main escape route became impassable. Given known human responses to fire, such an incident could have caused fatalities to sleeping or otherwise immobile occupants.
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