Search results for "Capillary Action"

ChemInform Abstract: Tuning the Defect Configurations in Nematic and Smectic Liquid Crystalline Shells

2013

Thin liquid crystalline shells surrounding and surrounded by aqueous phases can be conveniently produced using a nested capillary microfluidic system, as was first demonstrated by Fernandez-Nieves et al. in 2007. By choosing particular combinations of stabilizers in the internal and external phases, different types of alignment, uniform or hybrid, can be ensured within the shell. Here, we investigate shells in the nematic and smectic phases under varying boundary conditions, focusing in particular on textural transformations during phase transitions, on the interaction between topological defects in the director field and inclusions in the liquid crystal (LC), and on the possibility to relo…

Trapping and mobilization of residual fluid during capillary desaturation in porous media

1998

We discuss the problem of trapping and mobilization of nonwetting fluids during immiscible two-phase displacement processes in porous media. Capillary desaturation curves give residual saturations as a function of capillary number. Interpreting capillary numbers as the ratio of viscous to capillary forces the breakpoint in experimental curves contradicts the theoretically predicted force balance. We show that replotting the data against a novel macroscopic capillary number resolves the problem for discontinuous mode displacement.

Influence of the Electromagnetic, G-Jitter or Thermocapillary Forces on the Stability of the Stationary Buoyancy Convection

1992

Microgravity conditions seem to be very useful for crystal growth processes. Reduced gravitational force strongly weakens the buoyancy convection, so the convective oscillations in the melt become impossible [1]. This is the main reason of numerous attempts to obtain monocrystal materials with homogeneous internal structure in microgravity. On the other hand for non-isothermal fluid in microgravity conditions other driving forces become more significant than on the Earth. The main of them are thermocapillarity and g-jitter. The thermocapillary forces exist on the non-uniformly heated free liquid surfaces and cause motion of the fluid. The g-jitter appears in space unavoidably because of the…

Effects of Red Cell Spacing and Red Cell Movement Upon Oxygen Release Under Conditions of Maximally Working Skeletal Muscle

1989

The impacts of the particulate nature of blood upon capillary O 2 release have been studied extensively by Federspiel and Sarelius [8] and by Federspiel and Popel [9]. The latter authors found that the O 2 flux out of a capillary decreases rapidly as intracapillary red blood cell spacing increases. The O 2 flux out of a single RBC, however, is enhanced as long as the inter-erythrocytic plasma gap does not exceed the “zone-of-influence” of a single RBC, which they determined to be about 1 capillary diameter. In their model, they considered spherical red cells contained in a cylindrical tube filled with plasma, on the lateral surface of which a boundary Po 2 was specified. Based on earlier st…

Development of a triple-culture model of the alveolar-capillary barrier

2012

On-line analysis of carbonyl compounds with derivatization in aqueous extracts of atmospheric particulate PM10 by in-tube solid-phase microextraction…

2011

Abstract A new device for carbonyl compounds based on coupling on-line and miniaturizing both, sample pretreatment and chromatographic separation, is reported. Two capillary columns, a GC capillary column (95% methyl–5% phenyl substituted backbone, 70 cm × 0.32 mm i.d., 3 μm film thickness) in the injection valve for in-tube solid-phase microextraction (IT-SPME) and a Zorbax SB C18 (150 mm × 0.5 mm i.d., 5 μm particle diameter) LC capillary column were employed. Different combinations of IT-SPME and derivatization using 2,4-dinitrophenylhydrazine (DNPH) were examined for mixtures containing 15 carbonyl compounds (aliphatic, aromatic and unsaturated aldehydes and ketones). A screening analys…

A direct Capillary Liquid Chromatography with electrochemical detection method for determination of phenols in water samples

2010

A fast and direct method based on the use of Capillary Liquid Chromatography (LC) with electrochemical (EC) detection has been described for phenols pollutants in water samples. Concretely, phenol, o-cresol, 2-chlorophenol and bisphenol A have been selected as target analytes. The combination of Capillary LC with EC detection avoided the necessity of preconcentration steps typically used in environmental analysis. The sample injected volume was 2 μL. The achieved detection limits were between 1 and 2 μg/L and the linear dynamic range was up to 50 μg/L for all studied phenols. The precision and uncertainty were satisfactory. The analysis time per sample was 10 min. The proposed procedure has…

Advantages of monolithic over particulate columns for multiresidue analysis of organic pollutants by in-tube solid-phase microextraction coupled to c…

2011

Abstract The performance of a monolithic C 18 column (150 mm × 0.2 mm i.d.) for multiresidue organic pollutants analysis by in-tube solid-phase microextraction (IT-SPME)-capillary liquid chromatography has been studied, and the results have been compared with those obtained using a particulate C 18 column (150 mm × 0.5 mm i.d., 5 μm). Chromatographic separation has been carried out under isocratic elution conditions, and for detection and identification of the analytes a UV-diode array detector has been employed. Several compounds of different chemical structure and hydrophobicity have been used as model compounds: simazine, atrazine and terbutylazine (triazines), chlorfenvinphos and chlorp…

Exploring hand-portable nano-liquid chromatography for in place water analysis: Determination of trimethylxanthines as a use case.

2020

Abstract Analytical performance and optimization of figures of merit of a portable nano liquid chromatograph (NanoLC) with UV detection at 255 nm have been established for in place analysis. Methylxanthines: caffeine, theophylline and theobromine were selected as target analytes. A fast lab method based on IT-SPME coupled on line with capillary liquid chromatograph (CapLC) with diode array detection (DAD) was employed for comparative studies. IT-SPME and solid phase extraction were coupled off-line to NanoLC for improving instrumental parameters, mainly detection capacity and selectivity. IT-SPME or SPE/portable NanoLC based methods were superior in terms of chromatographic resolution and o…

Method and apparatus using selected superparamagnetic labels for rapid quantification of immunochromatographic tests

2009

Mika PA Laitinen1, Jari Salmela2, Leona Gilbert1, Risto Kaivola1, Topi Tikkala2, Christian Oker-Blom1, Jukka Pekola3, Matti Vuento11Department of Biological and Environmental Science; 2Department of Physics, University of Jyväskylä, Jyväskylä, Finland; 3Low Temperature Laboratory, Helsinki University of Technology, Helsinki, FinlandAbstract: A rapid method and instrumentation for quantification of immunochromatographic tests (ICT) are described. The principle and performance of the method was demonstrated by measuring the levels of human chorionic gonadotropin (hCG) present in urine. The test format was a sandwich assay using two distinct monoclonal antib…