17,112 research outputs found
Chromatographic separation and identification of some peptides in partial hydroylsates of gelatin
Recently we have been engaged in a study of the chemical structure of collagen and gelatin with the object of determining the sequence of the amino acid residues in the polypeptide chains of these proteins. In the course of this study we have made considerable progress in the chromatographic analysis of complex mixtures of peptides and we have isolated and identified several simple peptides which occur in partial hydrolysates of gelatin. The initial separation of the mixture into zones of one or more peptides has been made on a column of ion exchange resin; further separation of the peptides in each zone has been achieved by chromatographing in the form of dinitrophenyl (DNP) peptides on columns of silicic acid-Celite. It is to be hoped that the particular combination of chromatographic methods which has been successfully used in the present study will be helpful in the resolution of the complex mixtures which result from the partial hydrolysis of other proteins
Move-minimizing puzzles, diamond-colored modular and distributive lattices, and poset models for Weyl group symmetric functions
The move-minimizing puzzles presented here are certain types of one-player
combinatorial games that are shown to have explicit solutions whenever they can
be encoded in a certain way as diamond-colored modular and distributive
lattices. Such lattices can also arise naturally as models for certain
algebraic objects, namely Weyl group symmetric functions and their companion
semisimple Lie algebra representations. The motivation for this paper is
therefore both diversional and algebraic: To show how some recreational
move-minimizing puzzles can be solved explicitly within an order-theoretic
context and also to realize some such puzzles as combinatorial models for
symmetric functions associated with certain fundamental representations of the
symplectic and odd orthogonal Lie algebras
On the t-Term Rank of a Matrix
For t a positive integer, the t-term rank of a (0,1)-matrix A is defined to
be the largest number of 1s in A with at most one 1 in each column and at most
t 1s in each row. Thus the 1-term rank is the ordinary term rank. We generalize
some basic results for the term rank to the t-term rank, including a formula
for the maximum term rank over a nonempty class of (0,1)-matrices with the the
same row sum and column sum vectors. We also show the surprising result that in
such a class there exists a matrix which realizes all of the maximum terms
ranks between 1 and t.Comment: 18 page
Cyclic Matching Sequencibility of Graphs
We define the cyclic matching sequencibility of a graph to be the largest
integer such that there exists a cyclic ordering of its edges so that every
consecutive edges in the cyclic ordering form a matching. We show that the
cyclic matching sequencibility of and equal
Chemical Characterization and Subunit Hybridization of Human Hemoglobin H and Associated Compounds
Two abnormal hemoglobin components have been detected in association with thalassemiahemoglobin H disease. These components, as well as the major hemoglobin component, have been chemically characterized by determination of the amino acid composition, N-terminal amino acid sequence, tryptic peptide patterns, sedimentation coefficients, and subunit hybridization. The abnormal component in larger amount has a subunit formula of β_4; the abnormal component in smaller amount has a subunit formula of γ_4. The major hemoglobin component could not be distinguished chemically from normal hemoglobin A. Subunit hybridization studies of hemoglobins indicate that the affinities of the various subunits for one another are not equal
Relativistic spherical plasma waves
Tightly focused laser pulses as they diverge or converge in underdense plasma
can generate wake waves, having local structures that are spherical waves. Here
we report on theoretical study of relativistic spherical wake waves and their
properties, including wave breaking. These waves may be suitable as particle
injectors or as flying mirrors that both reflect and focus radiation, enabling
unique X-ray sources and nonlinear QED phenomena.Comment: 6 pages; 4 figure
European Preferences for Beef Steak Attributes
A choice experiment is used to evaluate how consumers in London, Frankfurt, and Paris value beef steaks with attributes such as: "hormone-free," "GM-free," farm-specific source verification, and domestic origin. The effect of various consumer characteristics on steak selection is also evaluated. Results suggest that European consumers are significantly heterogeneous in their preferences for beef steak attributes. French and German consumers have a higher willingness to pay to avoid genetically modified feed use than British consumers, while German and British consumers would pay more for growth hormone-free beef. French and German consumers are willing to pay for farm-specific source verification.beef, choice experiment, country of origin, genetically modified, hormones, preference heterogeneity, random parameters, source verification, Consumer/Household Economics,
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