Phase diagram of Si-doped spin-Peierls compound CuGeO3

We have performed magnetic susceptibility measurements on CuGe_1−xSi_xO₃ single crystals and obtained a detailed (T,x) phase diagram. In order to fully characterize the nature of the SP and AF phases in this diagram, we studied both order parameters by neutron diffraction as a function of temperature and Si concentration.     

High-depth-resolution SIMS analysis for InGaAs/InP interfaces

The influence of the primary ion impact conditions and of the surface chemical composition on beam-induced effects is investigated in order to achieve a high-depth-resolution analysis for the InGaAs/InP interfaces. The main result is that the oxygen adsorption with an appropriate pressure on the Cs⁺ bombarded surface can suppress the element-dependence of depth resolution which is an artefact in SIMS analysis.     

New vector bosons at a 1 TeVe + e − collider

We develop a simple and realistic strategy to identify the theoretical origin of aZ′ of massM _z′ ? 400 GeV if the latter were directly produced at a futuree ⁺ e ^? collider. A measurement of the muonic width and of two ratios of hadronic to muonic widths would lead to an almost complete identification within a very general class of extraU(1) models. Alternative models, though, would be better classified by measuring three longitudinal polarization asymmetries.     

First efficient uncharged reactivators for the dephosphylation of poisoned human acetylcholinesterase

Nerve agents are highly toxic organophosphorus compounds with strong inhibition potency against acetylcholinesterase (AChE). Herein, we describe two first extremely promising uncharged reactivators for poisoned human AChE with a superior or similar in vitro ability to reactivate the enzyme as compared to that of HI-6, obidoxime, TMB-4 and HL?-7.     

A novel and unusually long-lived chemiluminophore based on the 7-hydroxycoumarin scaffold

Synthesis and chemiluminescent properties of a new 1,2-dioxetane chemiluminophore bearing a 7-hydroxycoumarin moiety are presented. The 1,2-dioxetane decomposition ended up with strong and long-lived emission of light. This new structure opens way to the development of a new generation of bright chemiluminescent bio-probes.     

How Well Do We Handle the Sample Preparation,FT-ICR Mass Spectrometry Analysis,and Data Treatment of Atmospheric Waters?

FT-ICR MS (Fourier-transform ion cyclotron resonance mass spectrometry) analysis has shown great potential to aid in the understanding of the extremely high molecular diversity of cloud water samples. The main goal of this work was to determine the differences in terms of formula assignment for analytical (i.e., measurement replicates) and experimental replicates of a given cloud water sample. The experimental replicates, obtained by solid phase extraction, were also compared to the results obtained for freeze-dried samples to evaluate whether the presence of salts interferes with the analysis. Two S/N ratios, generally adopted for atmospheric samples, were evaluated, and three different algorithms were used for assignment: DataAnalysis 5.3 (Bruker), Composer (Sierra Analytics), and MFAssignR (Chemical Advanced Resolution Methods Lab). In contrast to other works, we wanted to treat this comparison from the point of view of users, who usually must deal with a simple list of m/z ratios and intensity with limited access to the mass spectrum characteristics. The aim of this study was to establish a methodology for the treatment of atmospheric aqueous samples in light of the comparison of three different software programs, to enhance the possibility of data comparison within samples.     

About a possible constancy of the total cross-section of the e+e− annihilation into hadrons

We show how a series of vector mesons can give a constant total cross-section in agreement with the experimental results up to 5 GeV. We discuss also the ratios n_π^°/n_π±,n_K/n_π and the breakdown of scaling in the inclusive spectra.     

Critical behaviour of a uniaxial ferromagnet,ErCl3·6H2O with predominant dipolar interactions

The parallel magnetic susceptibility χ of a uniaxial ferromagnet ErCl₃·6H₂O has been measured between 0.3 and 4.2K and specially near T_c = 0.353 K. The predominant contribution to the Curie-Weiss temperature is due to the dipolar interactions. χ is proportional to ?^?γ with $\text{? =}\text{T}\text{T}{}_{\mathrm{c}}\text{?1}$ in the range 10^?3 < ? < 5 × 10^?2. The γ value, γ = 1.01 ±0.03 is consistent with the theoretical prediction for a uniaxial dipolar ferromagnet.     

Anomalous effects ine + e − annihilation into boson pairs II.e + e −→ZZ, γZ, γγ

In application of the general procedure defined in I, we analyze various kinds of anomalous effects which could appear either in the leptonic or in the bosonic sector of the reactionse ⁺ e ^?→ZZ, γZ and γγ: excited electron, excited vector boson or isoscalar partner, anamalous three-neutral boson couplings, residual contact terms involving transverse or longitudinalZ-components. Results are given in view of SLC, LEP and future linear colliders.     

Crystal growth,structure, electron paramagnetic resonance and magnetic properties of (NH4)2V3O8

A method to grow single crystals of ammonium vanadate (IV, V) (NH₄)₂V₃O₈ has been devised. The crystal structure is tetragonal P4bm; residual factor is R = 0.030. Cell parameters are $\text{a = 8.891 ± 0.004}\text{A}\text{?}$ and $\text{c = 5.582 + 0.002}\text{A}\text{?}$. The V⁵⁺ atom lies at the center of a triangular pyramide (VO₄ tetrahedron) while the V⁴⁺ atom is on A 4-fold rotation axis at the center of a square-based pyramide VO₅ whose symmetry point group is almost C_4v with the short V = O bond lying along the 4-fold axis parallel to the c edge of the tetragonal cell. Crystals are thin platlets with (001) cleavage planes. The platlets have very often a square or rectangular shape limited by {100} or {110} planes. Each single crystal was not large enough to record a good e.p.r. spectrum, but by sticking on the same quartz plate a score of them it was possible to gather enough crystals so to record correct spectra and by orienting the plate to obtain resonance lines separately for g_∥ = 1.9263 et g_τ = 1.9755. Measurements at 283 K on powder samples gave times for spin-spin relaxation T₂ = 0.4 × 10^?7s and for spin-lattice relaxation T₁ = 1.6 × 10^?7s. The magnetic structure is characterized by an exchange narrowing ω_e = 3 × 10¹⁰rad/s which corresponds to a transition temperature of about 0.5 K. Static susceptibility measurements at high magnetic field show a paramagnetic behaviour with an antiferromagnetic interaction which is interpreted in the magnetic space group P_2c4bm as the interaction between V⁴⁺ ions from consecutive planes parallel to (001).