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Complex Mixtures: Mixtures of many components in inexact proportions, usually natural, such as Plant extracts; Venoms; and Manure. These are distinguished from Drug combinations which have only a few components in definite proportions.
 JoVE Environment

Removal of Trace Elements by Cupric Oxide Nanoparticles from Uranium In Situ Recovery Bleed Water and Its Effect on Cell Viability

1Division of Physical Therapy, Department of Orthopedics & Rehabilitation, University of New Mexico, 2Department of Ecosystem Science and Management, University of Wyoming, 3School of Pharmacy, University of Wyoming, 4Department of Environmental and Radiological Health Sciences, Colorado State University, 5Center for Environmental Medicine, Colorado State University, 6College of Pharmacy, California Northstate University

JoVE 52715

 JoVE Chemistry

Conducting Miller-Urey Experiments

1School of Chemistry and Biochemistry, Georgia Institute of Technology, 2Earth-Life Science Institute, Tokyo Institute of Technology, 3Institute for Advanced Study, 4Astromaterials Research and Exploration Science Directorate, NASA Johnson Space Center, 5Goddard Center for Astrobiology, NASA Goddard Space Flight Center, 6Geosciences Research Division, Scripps Institution of Oceanography, University of California at San Diego

JoVE 51039

 JoVE Biology

Reconstitution of a Transmembrane Protein, the Voltage-gated Ion Channel, KvAP, into Giant Unilamellar Vesicles for Microscopy and Patch Clamp Studies

1Institut Curie, Centre de Recherche, CNRS, UMR 168, PhysicoChimie Curie, Université Pierre et Marie Curie, 2Kavli Institute for Brain and Mind, University of California, San Diego, 3Molecular Physiology and Biophysics Section, National Institute for Neurological Disorders and Stroke, National Institute of Health

JoVE 52281

 Science Education: Essentials of Earth Science

Purification of a Total Lipid Extract with Column Chromatography

JoVE Science Education

Source: Laboratory of Jeff Salacup - University of Massachusetts Amherst

The product of an organic solvent extraction, a total lipid extract (TLE), is often a complex mixture of hundreds, if not thousands, of different compounds. The researcher is often only interested in a handful of compounds. The compounds of interest may belong to one of several classes of compounds, such as alkanes, ketones, alcohols, or acids (Figure 1), and it may be useful to remove the compound classes to which it does not belong in order to get a clearer view of the compounds you are interested in. For example, a TLE may contain 1,000 compounds, but the Uk'37 sea surface temperature proxy is based on only two compounds (alkenones) and the TEX86 sea surface temperature proxy is based on only four (glycerol dialkyl glycerol tetraethers). It would behoove the researcher to remove as many of the compounds they are not interested in. This makes the instrumental analysis of the compounds of interest (alkenones or GDGTs) less likely to be complicated by other extraneous compounds. In other cases, an upstream purification technique may have produced compounds you wish to now remove from the sample, such as the production of carboxylic acids during saponification in our

 Science Education: Essentials of General Chemistry

Le Châtelier's Principle

JoVE Science Education

Source: Laboratory of Dr. Lynne O'Connell — Boston College

When the conditions of a system at equilibrium are altered, the system responds in such a way as to maintain the equilibrium. In 1888, Henri-Lewis Le Châtelier described this phenomenon in a principle that states, "When a change in temperature, pressure, or concentration disturbs a system in chemical equilibrium, the change will be counteracted by an alteration in the equilibrium composition." This experiment demonstrates Le Châtelier's principle at work in a reversible reaction between iron(III) ion and thiocyanate ion, which produces iron(III) thiocyante ion: Fe3+(aq) + SCN- (aq) FeSCN2+ (aq) The concentration of one of the ions is altered either by directly adding a quantity of one ion to the solution or by selectively removing an ion from the solution through formation of an insoluble salt. Observations of color changes indicate whether the equilibrium has shifted to favor formation of the products or the reactants. In addition, the effect of a temperature change on the solution at equilibrium can be obs

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