Sur les proportions respectives de triangles uni,bi ou tricolores dans un tricoloriage des arêtes du n-emble

On determine le nombre maximum de triangles bicolores quand n tend vers l'infini, soit $\text{24}\text{25}\text{(}{}^{\mathrm{n}}{}_3\text{)+O(n}{}^2\text{)}$. On prouve aussi que, pour n assez grand, plus d'un triangle sur vingt-neuf est unicolore le methode suivie est susceptible de constituer une approche du probléme posé par une conjecture d'Erdos. Sos et Turan sur le nombre maximum de triangles tricolores.     

The thermal isomerization of cyclobutenes. XVI. 1,2-bis(trimethylsiloxy)cyclobutene

The gas phase thermal isomerization of 1,2-bis(trimethylsiloxy)cyclobutene has been studied in the temperature range 172°–204°C. The reaction is homogeneous, kinetically first order, and yields 2,3-bis(trimethylsiloxy)buta-1,3-diene as the only product. The rate constants fit the Arrhenius equation These results, taken with those obtained previously, demonstrate the insensitivity of the kinetics of the reaction to the nature of the groups substituted on the 1- and/or 2-positions of the cyclobutene ring.     

The FKG inequality for the Yukawa2 quantum field theory

We establish the FKG correlation inequality for the Euclidean scalar Yukawa₂ quantum field model and, when the Fermi mass is zero, for pseudoscalar Yukawa₂. To do so we approximate the quantum field model by a lattice spin system and show that the FKG inequality for this system follows from a positivity condition on the fundamental solution of the Euclidean Dirac equation with external field. We prove this positivity condition by applying the Vekua-Bers theory of generalized analytic functions.Research partially supported by the National Research Council of Canada.Alfred P. Sloan Foundation Fellow.     

Enantiospecific synthesis of optically active cyclohexylidene bromomethanes

Optically pure cyclohexylidene bromomethanes were prepared by stereospecific bromination alpha to a chiral sulfoxide, followed by the stereospecific pyrolytic elimination of the sulfoxide moiety.     

The crystal and molecular structure of bicyclo[2.2.1]-hept-2-en-5,6-dinitrosocobalt-η5-cyclopentadienide. Evidence for a nitroxyl diradical bidentate ligand

An accurate X-ray crystallographic structural study of a metal complex having a nitroxyl diradical as a bidentate ligand has been carried out. Bicyclo[2.2.1]-hept-2-en-5,6-dinitrosocobalt-η⁵-cyclopentadienide crystallizes in space group P$\text{1}$ with Z 2, a 8.245 ± 0.007, b 10.285 ± 0.016, c 7.888 ± 0.008 Å and α 59.276 ± 0.073, β 101.099 ± 0.053, γ 108.802 ± 0.067°. Intensities of 1831 independent reflections were used in the refinement of the structure to an R(F) of 4.6%. The bonding of the Co atom to the cyclopentadienyl ligand appears to be a normal pentahapto linkage. The lone double bond and the CC single bonds adjacent to the endo hydrogens of the norbornene fragment of the molecule are shorter than have previously been reported for this moiety. This study represents the first structural report of NO groups bridging to Co. The CoNO angles (129.4(3) and 128.9(3)°) and the NO stretching frequency (1357 cm^?1) of the title compound resemble values found in nitroxyl free radical compounds more closely than values found in bridging NO group compounds.     

Coherent production of π+ mesons in ν-neon interactions

The coherent production of π⁺ mesons by charged current neutrino interactions on neon nuclei in BEBC is compared to the predictions of the PCAC hypothesis and the meson dominance model. Good agreement is observed.