Search results for "column"

Novel porous carbon packings in reversed-phase high-performance liquid chromatography

1980

Abstract Porous carbon packings of particle size 5–20 μm were prepared by calcination of purified active carbons and cokes having narrow size ranges. Highly efficient columns packed with 10-μm particles were obtained by means of the high-viscosity slurry technique, and exhibited about 3000 theoretical plates at 100 mm length and optimal eluent flow-rate. The loading of columns, θ0.1, was determined to be 25–50 μg of solute per gram of packing. Eluotropic series of solvents were found to be similar to those on pyrocarbon-modified carbons and silicas. The log k′ values for homologous compounds increased linearly with the hydrocarbonaceous surface area at constant eluent composition. Studies w…

Micellar Liquid Chromatography: Fundamentals

2015

The reversed phase liquid chromatography (RPLC) mode with surfactant above the critical micellar concentration (CMC) has been called micellar liquid chromatography (MLC). In pure micellar systems, the retention behavior is explained by considering three phases or environments: surfactant-modified stationary phase, bulk aqueous solvent, and micellar pseudo-phase. Surfactant adsorption on the porous RPLC packing affects chromatographic retention, owing to the change of diverse surface properties of the stationary phase. In pure micellar systems, the retention behavior is explained by considering three phases or environments: surfactant-modified stationary phase, bulk aqueous solvent, and mice…

Climate controls on the Holocene development of a subarctic lake in northern Fennoscandia

2015

International audience; Climate exerts strong control over the functioning of northern freshwater ecosystems, yet their resilience and responses to climate forcing may vary. We examined postglacial development patterns in subarctic Lake Varddoaijavri to discern the impact of direct climate controls, catchment influence, and ontogenic processes on the ecological functioning of the lake over the Holocene. Subfossil diatom assemblages together with the elemental and stable isotopic (delta C-13, delta N-15) composition of sediment organic matter were used to examine climate-induced changes in the structure of the phototrophic community and transport of terrestrial organic matter from the catchm…

El miedo, arma política

1998

Photoconductivity in the columnar phases of a glassy discotic twin

1995

Sociedades fragiles

2001

Economía criminal y terror

2001

El honor de la sociedad civil israeli

2002

Antiamericanismo

2002

Retrieval of atmospheric CH4profiles from Fourier transform infrared data using dimension reduction and MCMC

2016

We introduce an inversion method that uses dimension reduction for the retrieval of atmospheric methane (CH4) profiles. Uncertainty analysis is performed using the Markov chain Monte Carlo (MCMC) statistical estimation. These techniques are used to retrieve CH4 profiles from the ground-based spectral measurements by the Fourier Transform Spectrometer (FTS) instrument at Sodankyla (67.4 degrees N, 26.6 degrees E), Northern Finland. The Sodankyla FTS is part of the Total Carbon Column Observing Network (TCCON), a global network that observes solar spectra in near-infrared wavelengths. The high spectral resolution of the data provides approximately 3 degrees of freedom about the vertical struc…