Lateral trapping

Fig. 7. Schematic diagram of forces exerted on a cell when using an inverted microscope with (A) epi-illumination (i.e., laser focused through the objective) or (B) transillumination (i.e., laser focused through the condenser). is the axial force, and Fl is the lateral trapping force. Curved arrows represent the laser beam waist and point in the direction of light propagation.

Tidal trapping when parcels of water are advected into lateral traps during one phase of the tidal cycle and then moved out in another results in an overall upstream transport. 

Geyer, W.R., Signell, R., and Kineke, G. (1998) Lateral trapping of sediment in a partially mixed estuary. In Physics of Estuaries and Coastal Seas Proceedings of the 8th International Biennial Conference on Physics of Estuaries and Coastal Seas (Dronkers, J., and Sheffers, M., eds.), pp. 115-126, Rotterdam, The Netherlands. 

The emulsifieation mechanism has been suggested to work by either of two methods. The first is by forming an emulsion, whieh becomes mobile and later trapped in downstream pores. The emulsion bloeks the pores, which thereby diverts flow and increases sweep efficiency. The seeond meehanism is by again forming an emirlsion, whieh beeomes mobile and carries oil droplets that it has entrained to downstream production sites. 

Migration describes the process which has transported the generated hydrocarbons into a porous type of sediment, the reservoir rock. Only if the reservoir is deformed in a favourable shape or if it is laterally grading into an impermeable formation does a trap for the migrating hydrocarbons exist. 

When an atom or molecule approaches a surface, it feels an attractive force. The interaction potential between the atom or molecule and the surface, which depends on the distance between the molecule and the surface and on the lateral position above the surface, detemiines the strength of this force. The incoming molecule feels this potential, and upon adsorption becomes trapped near the minimum m the well. Often the molecule has to overcome an activation barrier, before adsorption can occur. 

Early experiments witli MOT-trapped atoms were carried out by initially slowing an atomic beam to load tire trap [20, 21]. Later, a continuous uncooled source was used for tliat purjDose, suggesting tliat tire trap could be loaded witli tire slow atoms of a room-temperature vapour [22]. The next advance in tire development of magneto-optical trapping was tire introduction of tire vapour-cell magneto-optical trap (VCMOT). This variation captures cold atoms directly from the low-velocity edge of tire Maxwell-Boltzmann distribution always present in a cell... 

Future Trends. Methods of laser cooling and trapping are emerging as of the mid-1990s that have potential new analytical uses. Many of the analytical laser spectroscopies discussed herein were first employed for precise physical measurements in basic research. AppHcations to analytical chemistry occurred as secondary developments from 10 to 15 years later. 

Evaporative emissions from the fuel tank and carburetor have been controlled on all 1971 and later model automobiles sold in the United States. This has been accomplished by either a vapor recovery system which uses the crankcase of the engine for the storage of the hydrocarbon vapors or an adsorption and regeneration system using a canister of activated carbon to trap the vapors and hold them until such time as a fresh air purge through the canister carries the vapors to the induction system for burning in the combustion chamber. 

The reaction mixture and contents of the cold trap are then transferred (Note 7) to a 500-ml. distilling flask attached through a short fractionating column to a water-cooled condenser which is connected in series to a receiver, a trap cooled in a dry ice-acetone bath, and a hydrogen chloride absorption trap which may later be attached to a water pump. The mixture is then distilled until the pot temperature reaches 100° and practically all of the acetyl chloride has been driven over. 

The acetyl chloride obtained is yellow in color, probably because of the presence of the sulfenyl chlorides mentioned above. The addition of cyclohexene will discharge the color (although a darker color develops later) and redistillation then yields a stable water-clear product. The yield of acetyl chloride varies from 60% to 85%, depending on the care with which liquids are transferred and the vapors are trapped. O he amount... 

Tile a-dithione 91, generated by photolysis of 92, is transformed into the dithiin 93 (417o) in the absenee of a trapping agent. The eonversion was proposed to proeeed by a [4 + 2] eyeloaddition of 91 with its dithiete tautomer 94 leading to the dithietane 95, whieh was followed by loss of S2 (85JOC1550). Sueh [4 + 2] dimerizations are often eneountered in the ehemistry of 1,2-dithietes as diseussed later. 

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