Proton-proton correlations at small relative momentum in neon-nucleus collisions at E/A=400 and 800 MeV

Proton-proton small angle correlations have been measured in neon-nucleus collisions, using the 4 pi detector Diogene, at 400 and 800 MeV per nucleon incident energies. Values of the size of the emitting region are obtained by comparison with the Koonin formula, taking into account the biases of the apparatus. The dependence of the density on target mass and incident energy is also analysed.     

Determination of oxprenolol in human plasma by high-performance liquid chromatography, in comparison with gas chromatography and gas chromatography-mass spectrometry

A high-performance liquid chromatographic method for the quantitative assay of oxprenolol in human plasma is described. After addition of alprenolol as internal standard, the compounds are extracted from plasma at alkaline pH into an organic phase and back-extracted into an acidic aqueous phase. Separation of the plasma components and metabolites was achieved on a reversed-phase column. Concentrations down to 66 nmol/l (20 ng/ml) can be determined with UV detection at 222 nm. This technique compares favourably with gas chromatographic and gas chromatographic-mass spectrometric methods.     

Multivariate analyses for biomarkers hunting and validation through on-tissue bottom-up or in-source decay in MALDI-MSI: application to prostate cancer

The large amount of data generated using matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) poses a challenge for data analysis. In fact, generally about 1.10⁸–1.10⁹ values (m/z, I) are stored after a single MALDI-MSI experiment. This imposes processing techniques using dedicated informatics tools to be used since manual data interpretation is excluded. This work proposes and summarizes an approach that utilizes a multivariable analysis of MSI data. The multivariate analysis, such as principal component analysis–symbolic discriminant analysis, can remove and highlight specific m/z from the spectra in a specific region of interest. This approach facilitates data processing and provides better reproducibility, and thus, broadband acquisition for MALDI-MSI should be considered an effective tool to highlight biomarkers of interest. Additionally, we demonstrate the importance of the hierarchical classification of biomarkers by analyzing studies of clusters obtained either from digested or undigested tissues and using bottom-up and in-source decay strategies for in-tissue protein identification. This provides the possibility for the rapid identification of specific markers from different histological samples and their direct localization in tissues. We present an example from a prostate cancer study using formalin-fixed paraffin-embedded tissue.     

Baryon-Baryon correlations at small relative momentum in Neon- and Argon-nucleus collisions betweenE/A=200 and 1000 MeV

Two-proton correlation functions at small relative momentum have been systematically studied with the large solid angle detector DIOGENE at Saturne for interactions induced by Ne and Ar beams on various targets, and incident energies per nucleon ranging from 200 to 1000 MeV. From these distributions, informations on the space-time structure of the source have been derived as a function of the centrality of the collision, the target-projectile combinations and the incident energy, using the model of Koonin. Special attention has been devoted to take into account all experimental biases in order to get the distorted theoretical correlation curves before comparison to the experimental data. Other interesting conclusions have been obtained when comparing the extracted source radii to the dimensions of the overlapping volume of target by projectile in a pure geometrical model of the collision (clean cut geometry). Some results concerning fragment-fragment small angle correlations are also presented.     

New method to measure oxygen isotopic concentration ratios18O/16O by gamma-activation analysis,especially in biological media

The photonuclear reactions used for this isotopic analysis are as follows:¹⁶O(γ, n)¹⁵O threshold energy 15.7 MeV;¹⁸O(γ, p)¹⁷N threshold energy 16.3 MeV.¹⁵O is a pure β⁺ emitter of half-life 2.03 minutes, whereas¹⁷N presents a 4.2 second neutron emission. The principle of the method is founded on the simultaneous measurement of the above characteristic radioactivities, the intensities of which are proportional to the respective quantities of¹⁶O and¹⁸O present in the irradiated sample. The potentialities of this new oxygen isotope analysis method, based on the use of an electron accelerator, are described. Detection limit of 0.1 μg¹⁸O is easily attainable. The equipment designed and built to industrialise this technique is described. It allows a hundred samples to be analysed automatically, the accelerator, detection instruments and pneumatic transfer circuits being controlled by a logic system linked to an electronic chronometer.     

Analyse par activation aux photons gamma et aux particules chargees

The activation methods, nuclear reactions and chemical separation processes used to determine traces of carbon, nitrogen and oxygen in the metals and semiconductors considered are described briefly. The results obtained are reviewed. They mainly concern the following analyses: (1) determination of carbon and oxygen in alkaline metals; (2) determination of nitrogen and oxygen in refractory metals; (3) determination of carbon, nitrogen and particularly oxygen in various other metals; (4) determination of these same elements in semiconducting materials. In some cases the concentrations measured by γ photon or charged particle activation methods are compared with the results obtained by other techniques.     

2H( 3He, t)2p reaction at 2 GeV

The exclusive ²H( ³He, t)2p reaction has been studied at 2 GeV for energy transfers up to 500 MeV and triton angles up to 3.4^°. The protons were measured in the large acceptance magnetic detector DIOGENE, in coincidence with the forward tritons detected in a dedicated magnetic arm. The energy transfer spectra extend well above the pion threshold. However, in the region of Δ excitation, the yield is less than 10% of the inclusive ²H( ³He, t) cross-section, which indicates the small contribution of the ΔN ↦ NN process. The angular distributions of the two protons in their center of mass have been analysed as a function of energy transfer and triton angle and a Legendre polynomial decomposition has been achieved. These data have been compared to a model based on a coupled-channel approach for describing the NN and NΔ systems. Received: 21 October 2002 / Accepted: 15 November 2002 / Published online: 11 March 2003 RID="a" ID="a"e-mail: ramstein@ipno.in2p3.fr RID="†" ID="†"Deceased. RID="†" ID="†"Deceased. RID="d" ID="d"Present adress: School of Engineering, J?nk?ping University, P.O. Box 1026, S-551 11 J?nk?ping, Sweden. Communicated by M. Gar?on     

On the Supra-LUMO Interaction: Case Study of a Sudden Change of Electronic Structure as a Functional Emergence

The synergistic functioning of redox-active components that emerges from prototypical 2,2′-di(N-methylpyrid-4-ylium)-1,1′-biphenyl is described. Interestingly, even if a trans conformation of the native assembly is expected, due to electrostatic repulsion between cationic pyridinium units, we demonstrate that cis conformation is equally energy-stabilized on account of a peculiar LUMO (SupLUMO) that develops through space, encompassing the two pyridiniums in a single, made-in-one-piece, electronic entity (superelectrophoric behavior). This SupLUMO emergence, with the cis species as superelectrophore embodiment, originates in a sudden change of electronic structure. This finding is substantiated by insights from solid state (single-crystal X-ray diffraction) and solution (NOE NMR and UV-vis-NIR spectroelectrochemistry) studies, combined with electronic structure computations. Electrochemistry shows that electron transfers are so strongly correlated that two-electron reduction manifests itself as a single-step process with a large potential inversion consistent with inner creation of a carbon-carbon bond (digital simulation). Besides, absence of reductive formation of dimers is a further indication of a preferential intramolecular reactivity determined by the SupLUMO interaction (cis isomer pre-organization). The redox-gated covalent bond, serving as electron reservoir, was studied via atropisomerism of the reduction product (VT NMR study). The overall picture derived from this in-depth study of 2,2′-di(N-methylpyrid-4-ylium)-1,1′-biphenyl proves that trans and cis species are worth considered as intrinsically sharply different, that is, as doubly-electrophoric and singly-superelectrophoric switchable assemblies, beyond conformational isomerism. Most importantly, the through-space-mediated SupLUMO may come in complement of other weak interactions encountered in Supramolecular Chemistry as a tool for the design of electroactive architectures.     

Excitation of theΔ (1232)-resonance in proton-nucleus collisions

The excitation of theΔ resonance is observed in proton collisions on C, Nb and Pb targets at 0.8 and 1.6 GeV incident energies. The mass E₀ and widthΓ of the resonance are determined from the invariant mass spectra of correlated (p, π^±)-pairs in the final state of the collision: The mass E₀ is smaller than that of the free resonance, however by comparing to intra-nuclear cascade calculations, this reduction is traced back to the effects of Fermi motion, NN scattering and pion reabsorption in nuclear matter.