Proton‐Detected Solid‐State NMR Spectroscopy of Natural‐Abundance Peptide and Protein Pharmaceuticals

The natural way : A sensitive NMR spectroscopic method is developed to obtain well‐resolved two‐dimensional spectra (¹⁵N–¹H and ¹³C–¹H) for natural‐abundance (that is, without the need for isotopic enrichment) large‐molecule samples, such as biopharmaceuticals. This method gives structural insights on two lyophilized aprotinin samples and three insulin samples in lyophilized, microcrystalline suspension formulation (red; see picture) and fibril (green) forms.

     

Exploiting the 1,2,3‐Triazolium Motif in Anion‐Templated Formation of a Bromide‐Selective Rotaxane Host Assembly

Bromide is best : The first [2]rotaxane incorporating the triazolium anion‐binding motif is prepared using bromide anion templation. Preliminary anion‐binding investigations reveal that the rotaxane exhibits the rare selectivity preference for bromide over chloride ions.

     

The Number of Linearly Independent Binary Vectors with Applications to the Construction of Hypercubes and Orthogonal Arrays,Pseudo (<Emphasis Type="Italic">t</Emphasis>, <Emphasis Type="Italic">m</Emphasis>, <Emphasis Type="Italic">s</Emphasis>)-Nets and Linear Codes

We study formulae to count the number of binary vectors of length n that are linearly independent k at a time where n and k are given positive integers with 1kn. Applications are given to the design of hypercubes and orthogonal arrays, pseudo (t, m, s)-nets and linear codes.This revised version was published online in October 2004 with a corrected Received date.     

Check Character Systems using Quasigroups: I

We consider check character systems with one check character over an arbitrary quasigroup under different check equations which have one permutation. The aim of using such a system is to discover transmission errors. These systems always detect all single errors (that is errors only one component of a code word). We establish necessary and sufficient conditions for a general quasigroup check character system over this quasigroup to be able to detect all transpositions. jump transpositions, twin errors and jump twin errors. We also study capabilities of check character systems over loops, in particular, over Moufang loops and groups when the permutation in the check equations is the identify permutation.Communicated by: P. Wild     

A Novel Nitrone Cycloaddition/Rearrangement

Adamantanone-derived nitrone 4 and some other keto-nitrones, when reacted with aromatic and aliphatic aldehydes in refluxing toluene or tetrahydrofuran, formed the corresponding aldonitrones (Z)- 10 , the latter arising from the fragmentation of an initially formed 1 , 4 , 2 -dioxazolidine 6 to adamantan-2-one and an oxaziridine intermediate 11 , which then rearranges to (Z)- 10 .     

Complexation of uranium (VI) with the siderophore desferrioxamine B

Siderophores are microbial produced low molecular weight iron chelators and strongly bind to hard Lewis acids. The siderophore desfern oxamine B (DFO) has hydroxamate functional groups, similar to acetohydroxamic acid (AHA), a ligand that is proposed for actinide complexation in advanced separations. In the proposed separation involving AHA, the exact role of the complex in the extraction behavior of actinides is unclear DFO can be used to clarify the role of AHA if the fundamental interactions of DFO with actinides are determined Experiments with uranyl are performed from pH 3.5 to pH 10 showing three complexes. UO₂DFOH₂, UO₂DFOH, and UOOHDFOH with stability constants of log β(UO₂DFOH₂) = 22.93±0.04, log β(UO₂DFOH) = 17.12±0.35, and log β(UO₂OHDFOH) = 22.76±0.34.     

Amperometric biosensor for rapid measurement of 3-hydroxybutyrate in undiluted whole blood and plasma

A simple, rapid (< 30 s) electrochemical method for the determination of 3-hydroxybutyrate in whole blood or plasma is described, which uses NAD⁺-dependent d-3-hydroxybutyrate dehydrogenase immobilized at novel platinized carbon electrodes. The steady-state oxidation current produced by enzymatically generated NADH is measured at + 150 mV vs. Ag/AgCl. Enzyme electrodes produced by direct adsorption were stable for at least 3 months. Undiluted whole blood measurement with the sensor was compared with routine spectrophotometric analysis of plasma and perchloric acid extracts of whole blood.     

The Performance of an Electrorheological Fluid in Dynamic Squeeze Flow: The Influence of Solid Phase Size

This paper is concerned with an experimental investigation of a comparison of the rheological performance of an ER fluid, consisting of a carrier with a range of solid phase sizes, in oscillatory squeeze-flow under DC conditions. The fluid is sandwiched between two parallel plane electrodes, the upper one stationary and the lower one oscillating normal to its plane. It is seen that the dynamic performance of the fluid, in terms of the capacity for the transmission of imposed forces across the fluid, is highly dependent on the size of the dispersed solid phase and has an optimum value which is dependent on the mean value of the interelectrode gap. In addition the paper includes some measurements of the current through the fluid which may help to shed some further light on the mechanism of the ER effect. Finally the implications of the results to vibration control are discussed. Copyright 1999 Academic Press.