239PuN powder neutron diffraction study

A powder neutron diffraction study has been carried out on ²³⁹PuN, which was reported to be antiferromagnetic below T = 13 K. No magnetic ordering has been detected at 4K, the limit of the magnetic ordering which could be detected being μ_ord = 0.25μ_B per Pu atom. Moreover a neutron scattering length determination of ²³⁹Pu was performed which gave a value of b_²³⁹Pu = (0.81 ± 0.05) × 10^-12 cm at neutron wavelength $\text{λ = 1.219}\text{A}\text{?}$.     

Demonstration simple du theoreme de Kuratowski et de sa forme duale

Consideration of non planar graphs irreducible for edge-constractions gives a simpler proof of the well-known Kuratowski theorem (Theorem 2), from its classical dual form (Theorem 1).     

S-wave ππ scattering from the reaction π+p → π+pπ0π0 at 3.5 GeV/c

We have studied the 2π⁰ system produced in the reaction π⁺p → π⁺pπ⁰π⁰ at 3.5 GeV/c, using the heavy-liquid bubble chamber technique. The cross section of the reaction π⁺π^? → π⁰π⁰ saturates the S-wave unitarity limit around 750 MeV/c² and near threshold is indicative of an I=0 S-wave scaterring length larger than expected.     

Rare-gas oxide excimers in matrices

A model of interaction between low-lying electronic states of oxygen atoms and a host crystal has been designed to account for luminescence and chemiluminescence processes observed during far UV photolysis of oxygenated precursors in rare-gas matrices. A mechanism that involves different trapping sites (substitution in neon, insertion in argon, krypton and xenon) explains the observed features.     

Magnetic properties of neptunium diarsenide

The magnetic properties of a collection of single crystals of NpAs₂ have been investigated in the temperature range 4.2-300 K and in applied fields up to 100 kOe. For small magnetic fields (3 kOe), NpAs₂ is ferromagnetic up to T_IC=18 K, antiferromagnetic from 28 K to T_N=52 K, then paramagnetic. Both transitions are first order. When the applied field increases T_IC is shifted towards T_N. The antiferromagnetic phase disappears for H#62;30 kOe. The ferromagnetic range is characterized by a very large anisotropy. In the paramagnetic state, NpAs₂ has an effective moment 1.88 μ_B.     

Rearrangement thermique des adduits du tetracyanoethylene de 2H-pyrannes

The addition of tetracyanotehylene to 2H-pyrans 1 results in a mixture of two isomeric adducts 6. The thermal decomposition of the compounds 6 gives rise to both a small percentage of the retro Diels-Alder, and a new mode of evolution leading to a mixture of furans (E+Z) 7. A detailed interpretation of the ¹³C spectra of the compounds 7 was established by comparison with the ¹³C spectra of 2,5-diphenylfuran and trans-stilbene. The structure 7 is confirmed by chemical degradation.     

Die Anwendung der Stufen-Regeln für niedrige Grenzflächen spanung auf Gemische binärer Kohlenwasser stoffe

Ohne Zusammenfassung     

Majorants andL p norms

It is shown that ifG is an infinite compact abelian group, thenL ^p (G) has the upper majorant property only ifp is even orp=∞. The research for this paper was partially supported by National Research Council of Canada Operating Grant A-4822.