Reflection of cold atoms from an array of current-carrying wires

We report the realization of a new type of magnetostatic mirror for slowly moving atoms which comprises a planar array of parallel wires alternately carrying electric current in opposite directions. One of the features of this atomic mirror is that the magnetic field may be readily varied, switched or modulated by altering the current in the wires. Reflection signals close to 100% at a pulsed current of 3 A are demonstrated for a beam of free-falling laser-cooled cesium atoms at normal incidence. The current dependence of the reflection signals exhibits structure which is associated with the sequential onset of reflection of cesium 6² S _1/2 , F=4 atoms in the m=+4, +3, +2 and +1 magnetic states. Measurements of the spatial distribution of the reflected atoms indicate the reflection is predominantly specular at currents of 3 A. Received: 31 August 1998 / Accepted: 6 October 1998     

Comparison of connective tissue invaded by Lewis lung carcinoma to healthy connective tissue by means of micro‐Raman spectroscopy

We have measured the micro‐Raman spectra of mouse tissues invaded by Lewis lung carcinoma (LLC). We have also carried out categorical principal component analysis (CATPCA) on the acquired spectra. The results indicate that the tumor tissues can be well discriminated from normal tissues by the first two principal components extracted from the spectra. Furthermore, we have found that the concentrations of nucleic acids and lipids/fatty acids in the tumor are considerably higher than those in the normal tissue, whereas the collagen concentration is lower. These differences can be detected and characterized by Raman images using the 788 cm⁻¹ DNA/RNA band and the 1301 cm⁻¹ lipid/fatty acid band. Copyright © 2009 John Wiley & Sons, Ltd.     

The mass-mobility correlation redux: The conformational landscape of anhydrous biomolecules

Structural separations on the basis of gas-phase ion mobility-mass spectrometry are increasingly used for the analysis of complex biological samples. As a tool to elucidate biomolecular structure, ion mobility-mass spectrometry methods are unique in that direct molecular structural information is obtained for all resolved species, largely irrespective of the complexity of the sample. Computational approaches are used to interpret and discern structural details consistent with the empirical results. To a first approximation, correlations of mobility with mass allow for qualitative identification of the molecular class to which a particular species belongs. These correlations allow simultaneous characterization of different classes of biomolecules, which provides a means for combining omics measurements, such as lipidomics, proteomics, glycomics, and metabolomics, in the same analysis. Examination of the correlation of fine structure reveals that specific structural motifs, chemical functionality, chemical connectivity, and composition may also be determined, depending on the specific biomolecular class. Mapping the coarse and fine structure in ion mobility-mass spectrometry conformation space measurements provides an atlas for interpretation and discovery in complicated spectra.     

Bimolecular rate constants for diffusion in ionic liquids

The temperature dependence of the bimolecular rate constants for a diffusion controlled reaction involving neutral reactants have been directly determined in five commonly used ionic liquids over the temperature range 5-70 degrees C.     

Mass spectrometric determination of N-hydroxyphenacetin in urine using multiple metastable peak monitoring following thin-layer chromatography

This work describes a method for the quantitative determination of the labile, toxic N-hydroxy metabolite of phenacetin in urine. A thin-layer chromatography step was used for the preliminary purification of extracts, and the specificity of the assay was based on the monitoring of specific metastable decompositions in a forward geometry double-focussing mass spectrometer, in a manner analogous to conventional tandem mass spectrometry. This precluded the need for a gas chromatographic separation, thus minimizing thermal decomposition which can occur with these compounds, as well as enabling very rapid analyses.