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In stereochemistry, enantiomeric excess (ee) is a measurement of purity used for chiral substances. It reflects the degree to which a sample contains one enantiomer in greater amounts than the other. A racemic mixture has an ee of 0%, while a single completely pure enantiomer has an ee of 100%. A sample with 70% of one enantiomer and 30% of the ...
Biological specimens in an elementary school science lab.. A biological specimen (also called a biospecimen) is a biological laboratory specimen held by a biorepository for research.
Exome sequencing workflow: part 1. Exome sequencing, also known as whole exome sequencing (WES), is a genomic technique for sequencing all of the protein-coding regions of genes in a genome (known as the exome). [1]
Escherichia coli (/ ˌ ɛ ʃ ə ˈ r ɪ k i ə ˈ k oʊ l aɪ / ESH-ə-RIK-ee-ə KOH-lye) [1] [2] is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms.
In 1885, Theodor Escherich, a German pediatrician, first discovered this species in the feces of healthy individuals and called it Bacterium coli commune because it is found in the colon and early classifications of Prokaryotes placed these in a handful of genera based on their shape and motility (at that time Ernst Haeckel's classification of Bacteria in the kingdom Monera was in place [3]).
The world's first ESEM prototype. Starting with Manfred von Ardenne, [1] early attempts were reported of the examination of specimens inside "environmental" cells with water or atmospheric gas, in conjunction with conventional and scanning transmission types of electron microscopes.
Electroextraction (EE) is a sample enrichment technique that focuses charged analytes from a large volume of one phase into a small volume of aqueous phase through the application of an electric current. [1]
By column chromatography on regular silica gel with a hexane / ethyl acetate eluent (5:1), a 66.6% ee sample of a trifluoromethyl substrate is separated into several fractions ranging from 8.1% ee for the first fraction collected to > 99.9% ee for the last fraction collected.