Relaxation and diffusion of perfluorocarbon gas mixtures with oxygen for lung MRI

We report measurements of free diffusivity D(0) and relaxation times T(1) and T(2) for pure C(2)F(6) and C(3)F(8) and their mixtures with oxygen. A simplified relaxation theory is presented and used to fit the data. The results enable spatially localized relaxation time measurements to determine the local gas concentration in lung MR images, so the free diffusivity D(0) is then known. Comparison of the measured diffusion to D(0) will express the extent of diffusion restriction and allow the local surface-to-volume ratio to be found.     

Residual Coulomb interaction fluctuations in chaotic systems: the boundary, random plane waves, and semiclassical theory

New fluctuation properties arise in problems where both spatial integration and energy summation are necessary ingredients. The quintessential example is given by the short-range approximation to the first order ground state contribution of the residual Coulomb interaction. The dominant features come from the region near the boundary where there is an interplay between Friedel oscillations and fluctuations in the eigenstates. Quite naturally, the fluctuation scale is significantly enhanced for Neumann boundary conditions as compared to Dirichlet. Elements missing from random plane wave modeling of chaotic eigenstates lead surprisingly to significant errors, which can be corrected within a purely semiclassical approach.     

Analysis of serum protein precipitated with antiserum by matrix-assisted laser desorption ionization/time-of-flight and electrospray ionization mass spectrometry as a clinical laboratory test

Serum transferrin precipitated with specific antisera was analyzed by matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI/TOF-MS) and electrospray ionization-mass spectrometry (ESI-MS). When analyzed by MALDI, transferrin showed signal peaks that clearly could be separated from ions of IgG present in the immunoprecipitate. By ESI-MS, when the immunoprecipitates were loaded through a microcapillary polymeric reversed-phase column connected to the electrospray ionization probe, the mass spectra of transferrin were observed with a high signal-to-noise ratio and good resolution. By MALDI/TOF-MS, the observed molecular weight of normal transferrin was ～ 1.2 ku smaller when analyzed in the reflectron mode than in the linear mode. The observed molecular weight of transferrin treated with sialidase was approximately the same in both modes. A comparison between the results obtained in both modes may help to estimate the number of sialic acids on the protein molecule. A transferrin isoform with a molecular weight of ～2.2 ku less than the normal species was identified in the serum of patients with a carbohydrate-deficient glycoprotein syndrome as well as in heavy alcohol consumers.     

Quantum group invariant integrable n-state models with periodic boundary conditions

Using the methods of topological quantum field theory we construct aU _q [sl(n)] invariant integrable transfer matrix for the case ofq being a root of unity. It corresponds to a 2-dimensional vertex model on a torus with topological interaction w.r.t. its interior. By means of the nested Bethe ansatz method we analyse conformai properties and discuss the representational content of the Bethe ansatz solutions.     

Excited state properties of transition metal phosphine complexes

Phosphine ligands determine the excited state properties of a variety of coordination compounds. Phosphines not only influence metal-centered excited states, but participate directly in charge transfer transitions owing to their electron donating and accepting ability. Moreover, intraligand excited states are accessible if the phosphine carries suitable substituents. This diversity is illustrated by selected examples. The excited state behavior is discussed on the basis of spectral (absorption and emission) and photochemical properties of appropriate phosphine complexes.     

RFA as control method of the reactive sputtering process of TiN films

In-situ X-ray fluorescence (XRF) analysis has been used to control the deposition process of Ti-N films on steel substrates during reactive sputtering. The analysis system consisted of a tungsten X-ray tube, secondary targets of Cu, Fe and Cr and a Si (Li) detector. The sputtering off the Ti target has been determined indirectly by plasma monitoring using optical emissions spetroscopy (OES) of the Ti atoms, and the film growth has been measured directly by XRF analysis of the surface mass of Ti atoms deposited on the substrate. For zero bias voltage and varying N₂ flow the increment of surface mass per deposition time has been found to incrase linearly with the intensity of the OES signal of Ti. A negative bias voltage U_B100 V changes strongly the growth rate by resputtering effects, especially in the range where stoichiometric TiN is formed.