Microparticles trapping

Fast heating of droplets containing microparticles produces a dry skin of microparticles when the slurry does not contain macroparticles. In this case the dry skin of microparticles traps water inside the hollow sphere. Evaporation and evolution of the trapped water tends to produce a hole through the spherical grains obtained as a product. However, in the present process using a mixture of microparticles and macroparticles, the microparticles form a dry skin on the surface of the macroparticles. If the dry skin is too thick, fast heating may create craters on the otherwise uniform coating of the macroparticle. 

Li, X.F., Zhang, L.A., Wang, Y.X., Yang, X.L., Zhao, N., Zhang, XiL., et al. A bottom-up approach to fabricate patterned surfaces with asymmetrical Ti02 microparticles trapped in the holes of honeycomblike polymer film. J. Am. Chem. Soc. 133, 3736-3739 (2011)... 

Similar films are obtained from powdered molecular sieves loaded with organic molecules Zeolite Y microparticles embedded into a polystyrene film and loaded with appropriately sized transition metal complexes allow selective electron exchange reactions between trapped and mobile species in the film... 

Figure 7.3 shows the two-beam photon-force measurement system using a coaxial illumination photon force measurement system. Two microparticles dispersed in a liquid are optically trapped by two focused near-infrared beams ( 1 pm spot size) of a CW Nd YAG laser under an optical microscope (1064 nm, 1.2 MWcm , lOOX oil-immersion objective, NA = 1.4). The particles are positioned sufficiently far from the surface of a glass slide in order to neglect the interaction between the particles and the substrate. Green and red beams from a green LD laser (532 nm, 21 kWcm ) and a He-Ne laser (632.8 nm, 21 kW cm ) are introduced coaxially into the microscope and slightly focused onto each microparticle as an illumination light (the irradiated area was about 3 pm in diameter). The sizes of the illumination areas for the green and red beams are almost the same as the diameter of the microparticles (see Figure 7.4). The back scattered light from the surface of each microparticle is...

Figure 7.4 A microscope image of two trapped microparticles in water, illuminated by a green and red laser beam, respectively. The diameter of the particles is 3 xm.

Won, J., Inaba, T., Masuhara, H., Fujiwara, H., Sasaki, K, Miyawaki, S. and Sato, S. (1999) Photofhermal fixation of laser-trapped polymer microparticles on polymer substrates. Appl. Phys. Lett., 75, 1506-1508. 

Let T2J be the concentration of uncharged traps in the depletion band of the Au-ZnO microparticle contacts in the equilibrium conditions. Being exposed to light, the traps will be ionized giving electrons to the conduction band of the semiconductor. If we designate the concentration of nonequilibrium ionized traps N, then the rate of traps accumulation under illumination will be... 

Tona, M. Kimura, M., Parallel plate ion trap useful for optical studies of microparticles, Rev. Sci. Instrum. 2004, 75, 2276 2279... 

Kitamura, N. Kitagawa, F., Optical trapping chemical analysis of single microparticles in solution, J. Photochem. Photobiol. C Photochem. Rev. 2003, 4, 227 247... 

In a particle concentration fluoroimmunoassay system that is based on microtiter plates with 0.22-/ filters on the bottoms, microparticles are used with a flowthrough wash system. Either fluorescein-labeled antibodies or cells serve as labels.(41) Car-boxyfluorescein diacetate, which crosses the cell membrane, is hydrolyzed by cytoplasmic esterases, thereby trapping carboxyfluorescein within the cell. The method is also useful for screening and isotyping antibodies. 

Yang, M., J. M. Dale, W. B. Whitten, and J. M. Ramsey, Laser Desorption Mass Spectrometry of a Levitated Single Microparticle in a Quadrupole Ion Trap, Anal. Chem., 67, 1021-1025 (1995a). 

In another report, microparticles and biological cells were trapped in microvortices produced in the microchambers constructed in a PDMS chip. Figure 8.25 shows different designs of the microchambers, in which only Figures 8.25c and 8.25d produced stable micro vortices. Rotational motion of either particles (10 pm) or cells (B lymphocytes) was studied in these microvortices [1173]. 

Shelby, J.P., Mutch, S.A., Chiu, D.T., Direct manipulation and observation of the rotational motion of single optically trapped microparticles and biological cells... 

First we briefly summarize the existing schemes and their range of applicabilities. In a circularly polarized optical trap, birefringent microparticles are seen to rotate [2, 3], Microobjects, when trapped in a spiral optical pattern, have also been observed to rotate [4-6]. Rotations of specifically fabricated rather big rotors under an optical tiap have been... 

Microspheres can be used for chemoembolization of tumors in which the vasculature is blocked while anticancer agent is released from the trapped microparticles. 

N. K. Metzger, E.M. Wright, W. Sibbett, K. Dholakia, Visualization of optical binding of microparticles using a femtosecond fiber optical trap. Opt. Exp. 14 (2006) 3677. 

Very informative studies were conducted by Hatch and his associates (5, 14, 22, 23) on the penetration and retention of microparticles in the respiratory tract of human volunteers. They devised a special partitioning apparatus whereby the different fractions of respiratory air could be trapped and analyzed. The subjects were placed in a mechanical respirator in order to control the respiratory cycle, and were exposed to uniformly sized particles of clay. It was... 

M.J. Ruedas-Rama, A. Dominguez-Vidal, S. Radel, B. Lendl, Ultrasonic trapping of microparticles in suspension and reaction monitoring using Raman microspectroscopy, Anal. Chem. 79 (2007) 7853. 

H.M. Hertz, Standing-wave acoustic trap for nonintrusive positioning of microparticles, Journal of Applied Physics, 78(8), 4845 849 (1995). 

S., Trapping of microparticles in the near field of an ultrasonic transducer. Ultrasonics, 43, 293, 2005. 

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