Design of a new,twelve-channel electrophoretic apparatus based on the Gradiflow technology

The Gradiflow technology, originally designed to carry out binary, size-based and charge sign-based electrophoretic protein separations, has been extended to simultaneously obtain multiple protein fractions from a single electrophoretic separation. The separation unit of the new apparatus houses the anode and cathode compartments and up to twelve shallow separation compartments through which the background electrolyte solution that contains the separated protein fractions is recirculated. The separation compartments are formed from grids as thin as 1.2 mm and polyacrylamide membranes as thin as 0.15 mm, all with corresponding multiple inlet and outlet ports. The average pore size of the polyacrylamide membranes can be varied to permit passage of proteins in the 5000-800 000 molecular mass range. The electric field, orthogonal to the flow paths of the recirculated background electrolyte, selectively moves the sample components across the polyacrylamide separation membranes. Selective protein transport can be achieved by exploiting differences in either the relative size of the proteins or the charge sign of the proteins. The advantages of the new apparatus stem from the synergistic combination of the short electrophoretic transfer distances, high electric field strength, large effective surface areas of the separation membranes, and the great flexibility with which apparati containing one to twelve separation compartments can be created.     

Simultaneous and stereoselective formation of planar and axial chiralities in enantiopure sulfinyl iron diene complexes

[reaction: see text] Enantiopure (1Z,3E)-1-sulfinyl dienes bearing an o-dithianylphenyl group can be prepared and complexed with (bda)Fe(CO)(3) to afford the corresponding sulfinyl diene iron(0) tricarbonyl complexes. This diastereoselective complexation introduces planar and axial chirality simultaneously, with a high degree of facial selectivity as well as atropselectivity. Dynamic kinetic resolution is likely to be the origin of the atropselectivity.     

The evaluation of rate constants in rate laws containing two terms

A simple computerized method using APL is described which gives the rate constants for systems obeying the rate law –d[A]/dt = k₁[A][B] + k₂[A] ^m [B]^l from sets of concentrations and times. Applications are discussed.     

Gravity and large black holes in Randall-Sundrum II braneworlds

We show how to construct low energy solutions to the Randall-Sundrum II (RSII) model by using an associated five-dimensional anti-de Sitter space (AdS(5)) and/or four-dimensional conformal field theory (CFT(4)) problem. The RSII solution is given as a perturbation of the AdS(5)-CFT(4) solution, with the perturbation parameter being the radius of curvature of the brane metric compared to the AdS length ?. The brane metric is then a specific perturbation of the AdS(5)-CFT(4) boundary metric. For low curvatures the RSII solution reproduces 4D general relativity on the brane. Recently, AdS(5)-CFT(4) solutions with a 4D Schwarzschild boundary metric were numerically constructed. We modify the boundary conditions to numerically construct large RSII static black holes with radius up to ~20?. For a large radius, the RSII solutions are indeed close to the associated AdS(5)-CFT(4) solution.     

Synthesis of epoxybenzo[d]isothiazole 1,1-dioxides via a reductive-Heck, metathesis-sequestration protocol

An atom-economical purification protocol, using solution phase processing via ring-opening metathesis polymerization (ROMP) has been developed for the synthesis of tricyclic sultams. This chromatography-free method allows for convenient isolation of reductive-Heck products and reclamation of excess starting material via sequestration involving metathesis catalysts and a catalyst-armed Si-surface.     

Coxeter groups,Coxeter monoids and the Bruhat order

Associated with any Coxeter group is a Coxeter monoid, which has the same elements, and the same identity, but a different multiplication. (Some authors call these Coxeter monoids 0-Hecke monoids, because of their relation to the 0-Hecke algebras—the q=0 case of the Hecke algebra of a Coxeter group.) A Coxeter group is defined as a group having a particular presentation, but a pair of isomorphic groups could be obtained via non-isomorphic presentations of this form. We show that when we have both the group and the monoid structure, we can reconstruct the presentation uniquely up to isomorphism and present a characterisation of those finite group and monoid structures that occur as a Coxeter group and its corresponding Coxeter monoid. The Coxeter monoid structure is related to this Bruhat order. More precisely, multiplication in the Coxeter monoid corresponds to element-wise multiplication of principal downsets in the Bruhat order. Using this property and our characterisation of Coxeter groups among structures with a group and monoid operation, we derive a classification of Coxeter groups among all groups admitting a partial order.