Finding the <Emphasis Type="Italic">K</Emphasis> Least Cost Paths in an Acyclic Activity Network

This paper presents an application of the Kth shortest path problem to an agricultural problem-dairy waste management. It goes on to compare several algorithms for this problem and concludes by using computational results to provide a basis for choosing the most appropriate algorithm for a variety of applications.     

Classifying multi-frequency fisheries acoustic data using a robust probabilistic classification technique

A robust probabilistic classification technique, using expectation maximization of finite mixture models, is used to analyze multi-frequency fisheries acoustic data. The number of clusters is chosen using the Bayesian Information Criterion. Probabilities of membership to clusters are used to classify each sample. The utility of the technique is demonstrated using two examples: the Gulf of Alaska representing a low-diversity, well-known system; and the Mid-Atlantic Ridge, a species-rich, relatively unknown system.     

Resistive-pulse studies of proteins and protein/antibody complexes using a conical nanotube sensor

There is increasing interest in using nanopores in synthetic membranes as resistive-pulse sensors for molecular and macromolecule analytes. In general, this method entails measuring current pulses associated with translocation of the analyte through the nanopore sensor element. A key challenge for this sensing paradigm is building selectivity into the protocol so that the current pulses for the target analyte can be distinguished from current pulses for other species that might be present in the sample. We show here that this can be accomplished with a protein analyte by adding to the solution an antibody that selectively binds the protein. We demonstrate this concept using bovine serum albumin (BSA) and a Fab fragment from a BSA-binding polyclonal antibody. Because the complex formed upon binding of the Fab to BSA is larger than the free BSA molecule, the current-pulse signature for the BSA/Fab complex can be easily distinguished from the free BSA. Furthermore, the BSA/Fab pulses can be easily distinguished from the pulses obtained for the free Fab and from pulses obtained for a control protein that does not bind to the Fab. Finally, we also show that the current-pulse signature for the BSA/Fab complex can provide information about the size and stoichiometry of the complex.     

Efficient route to C2 symmetric heterocyclic backbone modified cyclic peptides

[reaction: see text] A tandem dimerization-macrocyclization approach using 1,3-dipolar azide-alkyne cycloaddition reactions has been employed in the facile and convergent solution phase syntheses of C2 symmetric cyclic peptide scaffolds bearing triazole epsilon2-amino acids as dipeptide surrogates.     

Crystal structure of a pentanuclear gold-silver cluster complex

The title compound, [C₁₆H₃₆N]⁺[C₄₈H₃₀Au₃Ag₂]^–, crystallizes in the triclinic space groupP1^–1, witha=18.199(12),b=19.210(8),c=19.270(9)Å,=71.34(3)°=76.43(4)° =72.95(5)° andZ=4, with two independent molecules in the asymmetric unit. The structure was solved by direct methods and refined by full-matrix least squares methods toR=0.072 for 3739 observed reflections. The metal atoms have a trigonal-bipyramidal arrangement with the three Au atoms forming an equilateral triangle and two Ag atoms occupying apical positions. Each Au atom is -bonded to phenylethynyl ligands in a linear coordination. Each Ag atom is asymmetrically pi-bonded to three alkyne groups. The Au-Au distances lie in the range of 3.934–4.010 A, indicating the lack of Au-Au bond.     

Structure and absolute configuration of 9-desoxy-9-chloroquinine,C20H23N2OCl

The title compound crystallizes in the orthorhombic space groupp2₁2₁2₁a=8.674(1),b=8.944(1),c=23.255(4) Å,Z=4. The structure was solved by direct methods, and refined by full-matrix least squares toR=0.047 for 1472 observed reflections. Determination of the absolute configuration [S at C(9)] enabled a discrepancy in the literature concerning the stereochemical outcome of the reaction between SOCl₂ and quinine to be resolved.     

Crystal and molecular structure of 3,3-diphenyl-3-phosphoniabicyclo[3.2.1]octane bromide monohydrate

The title compound crystallizes in the monoclinic space groupP2₁/n, witha=13.316(2),b=18.513(3),c=14.621(4) Å,=90.73(2)°,Z=8, and two independent molecules in the asymmetric unit. The structure was solved by heavy-atom methods and refined to a finalR value of 0.036. The phosphoranium ring adopts a chair conformation, which is substantially flattened at the phosphorus end. The ring conformation and torsion angles are compared with those of similar compounds.