Microcapillaries

The instrumentation of HdC, including a pump, an injector, a column (set), a detector, and a recorder or computer, is very similar to size exclusion chromatography SEC). The essence of this technique is the column. There are two types of HdC columns open microcapillary tubes and a nonporous gel-packed column. This chapter emphasizes column technology and selection and the applications of this technique on the molecular weight analysis of macromolecules. 

II. OPEN MICROCAPILLARY TUBULAR HYDRODYNAMIC CHROMATOGRAPHY (OTHdC)... 

HdC separation also occurs in the interstices of a packed column, although the configuration of channels is not as simple as a microcapillary tube. The... 

Tsuda, T. and Novotny, M., Packed microcapillary columns in high performance liquid chromatography, Anal. Chem., 50, 271, 1978. 

Figures 4c and 4d demonstrate OCT images of two seeds out of the GMF group after 60 minutes when turgescence has started. One can distinctly detect darker layers of watered zones and the heterogeneous zones of water absorption. The water absorption zones merged in a united system of microcapillary vessels with sizes 50-10 pm. Individual differences in the structure of the water absorption zones in the seeds are also clearly seen.

Fig. 4 a - dry barley seed (control group) b - dry barley seed (GMF group) c, d - 2 different seeds from GMF group after 60 minutes of turgescence. Arrows indicate microcapillary vessels e, f - 2 different seeds from the control group (the same time period). 

Fig. 16. a,b Two parallel microcapillary connection concepts tube-and-shell multitubular and branched tube arrangements (Courtesy of ACS)... 

Utada AS, Lorenceau E, Link DR, Kaplan PD, Stone HA, Weitz DA (2005) Monodisperse double emulsions generated from a microcapillary device. Science 308 537-541... 

Fig. 13.1 Photonic sensors that are either based on MNF sensing ((a),(b), (d), (e), (f)) or use MNF for the input and output connection (c), (g) (j). (a) straight MNF sensor with surrounding evanescent field (b) straight MNF sensor coated with bio or chemical layer and surrounding evanescent field (c) generic structure of MNF based optical sensor with surrounding evanescent field (d) straight MNF sensor (e) MNF loop resonator (MLR) sensor (f) MNF coil resonator (MCR) sensor (g) MNF/microsphere sensor (h) MNF/microdisk sensor (i) MNF/micro cylinder sensor (j) MNF/microcapillary sensor (k) a sensor composed of an MNF coupled to a series of microcylinders (optical fibers)...

Fig. 13.25 (a) Measurement of the LCORRS sensitivity, (b) The sensitivity of the LCORRS measured when the silica microcapillary was not removed completely (curve 1) and for the removed microcapillary (curve 2). Curve 3 is the sensitivity predicted for the Teflon AF matrix. Reprinted from Ref. 54 with permission. 2008 Optical Society of America... 

Fig. 13.26 (a) Set of parallel MNFs and parallel microcylinders coupled to each other, (b) Two microspheres coupled to an MNF (from Ref. 38). (c) Two microcapillaries coupled to an MNF imbedded in a low index polymer. Reprinted from Ref. 69 with permission. 2008 Optical... 

Here functions Qnt X), Qj(X), and QP(X) can be determined experimentally using calibration samples. If these functions are linear independent then the parameters Ank, A, and Ap can be uniquely determined from the variation of P /1, , n2,. .. /( . /. / considered as a function of X. In particular, the side effects, i.e., the temperature and pressure dependences, can be eliminated from the transmission spectrum. The sensing method based on this simple idea was applied in Ref. 69 for determination of microfluidic refractive index changes in two microcapillaries coupled to a single MNF illustrated in Fig. 13.26c. The developed approach allowed to compensate the side temperature and pressure variation effects. 

A recent experiment compared for the first time pollutant degradation by chemotactic bacteria and nonchemotactic mutants [54]. The result suggested an important role of chemotaxis in the bioremediation of contaminated soils. In a heterogeneous system, in which naphthalene was supplied from a microcapillary, a 90% reduction in the initial amount of naphthalene took six hours with the chemotactic wild-type Pseudomonas putida PpG7, while a similar reduction with either a chemotaxis-negative or a nonmotile mutant strain took about five times longer. Only the systems inoculated with the chemotactic strain exhibited degradation rates in excess of the rate of naphthalene diffusion from the... 

Single-molecule detection in confocal spectroscopy is characterized by an excellent signal-to-noise ratio, but the detection efficiency is in general very low because the excitation volume is very small with respect to the whole sample volume, and most molecules do not pass through the excitation volume. Moreover, the same molecule may re-enter this volume several times, which complicates data interpretation. Better detection efficiencies can be obtained by using microcapillaries and micro structures to force the molecules to enter the excitation volume. A nice example of the application of single-molecule detection with confocal microscopy is... 

Aravamudhan, Rahman, and Bhansali. [70] developed a micro direct ethanol fuel cell with silicon diffusion layers. Each silicon substrate had a number of straight micropores or holes that were formed using microelec-tromechanical system (MEMS) fabrication techniques. The pores acted both as microcapillaries/wicking structures and as built-in fuel reservoirs. The capillary action of the microperforations pumps the fuel toward the reaction sites located at the CL. Again, the size and pattern of these perforations could be modified depending on the desired properties or parameters. Lee and Chuang [71] also used a silicon substrate and machined microperforations and microchannels on it in order to use it as the cathode diffusion layer and FF channel plate in a micro-PEMFC. 

Tsuda, T, Tanaka, L, and Nakagawa, G., Racked microcapillary hquid-chromatography with reduced Id columns, Journal of Chromatography 239(Apr), 507-513, 1982. 

Licklider, L. J., Thoreen, C. C., Peng, J. M., and Gygi, S. R, Automation of nanoscale microcapillary liquid chromatography-tandem mass spectrometry with a vented column, Analytical Chemistry 74(13), 3076-3083, 2002. 

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