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Laser light scattered from particles in the streaming protoplasm of a living cell is shifted in frequency by the Doppler effect. The spectrum of the scattered light can be measured and interpreted to infer details of the velocity distribution in the protoplasm. We have developed this approach to study the protoplasmic streaming in the fresh-water alga Nitella. Our results indicate a characteristic flow pattern to which diffusion makes a negligible contribution. No difference in the velocity of particles of different size is indicated. The streaming velocity linearly with temperature with a supraoptimal temperature of 34 degrees C, and the velocity distribution becomes narrower at high temperatures. The protoplasmic streaming can be inhibited by laser light, and this effect has been used to study the photoresponse of the algae. Using beam diameters of about 50 mum, we have shown that the inhibition is very local, becoming minimal at a displacement of about 200 mum in the upstream direction and 400 mum in the downstream direction. Prolonged exposure produces a bleached area free of chloroplasts, which is three orders of magnitude less sensitive to photoinhibition.

Field as well as laboratory gas chromatography-mass spectrometry (GC-MS) systems are limited in several ways. Laboratory systems with air circulation ovens are bulky, power inefficient, and have a narrow range of temperature programming rates. Commercial field-portable GC-MS systems are too heavy, and many are limited to isothermal column temperature control. A resistively heated low thermal mass (LTM) GC system has been developed that can overcome most of these limitations, offering laboratory-level performance, or better, in a small, lightweight package. A prototype LTM GC was developed and evaluated in parallel with a commercial laboratory GC-MS used as a benchmark. A series of hydrocarbons, a Grob mixture, and a drug mixture critical pair of cocaine and nortriptyline were analyzed under different chromatographic conditions, and the performance of both systems was compared in terms of speed, efficiency, temperature control, resolution, precision, and power demand. The LTM GC was found to provide performance that was equivalent to the lab-based commercial GC when conventional temperature ramp rates were used (up to 30 • C/min). The LTM GC provided additional advantages over the conventional GC system in terms of positive or negative temperature ramping rates and range, cool-down time reduction, and lower power requirements (1-5 W/m). This new GC system demonstrated a capability for a wider range of linear temperature programming rates providing analysts flexibility when performing established forensic methods. Method development and implementation of the LTM GC was successful in demonstrating GC analyses that are controllable, reproducible, and fieldable.

Data are presented which demonstrate that the laser light scattered from the protoplasm of living algae cells is Doppler shifted by the streaming motion of the macromolecules and particles in the protoplasm. The laser-light-scattering spectra are used to determine the velocities and velocity distributions inside the cells.We show that a finite cutoff of the hydrodynamic modes (order fluctuations) in the nematic liquid-crystalline phase explains the measured spin-lattice relaxation in this phase. A calculation of T { based upon such a cutoff and a fit to the data of MBBA (4-wmethoxybenzylidene-4'~rc-butylaniline) show this cutoff to be 1 molecular length. At T ip frequencies, far from the cutoff, order fluctuations are shown to be the dominant relaxation mechanism. This is done by comparing the predicted angular dependence of T i0 for these modes with that measured in MBBA.