Levels in152Gd and152Sm populated by the decay of152Eu

The energy level schemes of¹⁵²Gd and¹⁵²Sm have been established on the basis of singlesγ-spectra, andγ- γ coincidence measurements. Ge(Li) detectors were used to study the gamma spectra produced in the EC/β⁺ and β^? decays of¹⁵²Eu to¹⁵²Sm and¹⁵²Gd, respectively. Thirteen new transitions are reported and data from eleven coincidence gates enabled five new levels to be suggested. Relative intensities and logf t values were calculated and spin/parities deduced. Comparisons are made with new predictions of the Interacting Boson Model.     

Dissipation rate correction methods

Dissipation rates of the turbulent kinetic energy and of the scalar variance are underestimated when the measurement resolution of the small scales of a turbulent flow field are insufficient. Results are presented of experiments conducted in a salt-stratified water tunnel (Schmidt number ∼700). Dissipation rates are determined to be underestimated, and thus correction techniques based on velocity structure functions and mixed-moment functions are proposed. Dissipation rates in laboratory experiments of shear-free, grid-generated turbulence are determined from balance calculations of the kinetic energy and scalar variance evolution equations. Comparisons between the structure function and balance estimates of dissipation show that the corrections are O(1) for the kinetic energy dissipation rate, and are O(100) for the scalar variance dissipation rate. This difference is due to the lack of resolution down to the Batchelor scales that is required for a high Schmidt number flow. Simple correction functions based on microscale Reynolds numbers are developed for both turbulent kinetic energy and scalar variance dissipation rates. Application of the technique to the results of laboratory experiments of density stratified turbulence, sheared turbulence, and sheared density stratified turbulence yields successful corrections. It is also demonstrated that the Karman–Howarth equality (and the analogous Yaglom equation) that relates second and third-order structure functions to dissipation rates is valid for both unstrained (decaying grid-generated turbulence) and density stratified and sheared turbulence at least up to the magnitudes of strains of the current experiments Nt∼10, St∼10, respectively. This is helpful for it allows the use of these equations in the analysis of turbulence even when the large scale background profiles of velocity and scalar are unknown.     

Reactivity of bis(2,2,5,5-tetramethyl-2,5-disila-1-azacyclopent-1-yl)tin with CO(2), OCS, and CS(2) and comparison to that of bis[bis(trimethylsilyl)amido]tin

The heterocumulenes carbon dioxide (CO(2)), carbonyl sulfide (OCS), and carbon disulfide (CS(2)) were treated with bis(2,2,5,5-tetramethyl-2,5-disila-1-azacyclopent-1-yl)tin {[(CH(2))Me(2)Si](2)N}(2)Sn, an analogue of the well-studied bis[bis(trimethylsilyl)amido]tin species [(Me(3)Si)(2)N](2)Sn, to yield an unexpectedly diverse product slate. Reaction of {[(CH(2))Me(2)Si](2)N}(2)Sn with CO(2) resulted in the formation of 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane, along with Sn(4)(μ(4)-O){μ(2)-O(2)CN[SiMe(2)(CH(2))(2)]}(4)(μ(2)-N═C═O)(2) as the primary organometallic Sn-containing product. The reaction of {[(CH(2))Me(2)Si](2)N}(2)Sn with CS(2) led to formal reduction of CS(2) to [CS(2)](2-), yielding [{[(CH(2))Me(2)Si](2)N}(2)Sn](2)CS(2){[(CH(2))Me(2)Si](2)N}(2)Sn, in which the [CS(2)](2-) is coordinated through C and S to two tin centers. The product [{[(CH(2))Me(2)Si](2)N}(2)Sn](2)CS(2){[(CH(2))Me(2)Si](2)N}(2)Sn also contains a novel 4-membered Sn-Sn-C-S ring, and exhibits a further bonding interaction through sulfur to a third Sn atom. Reaction of OCS with {[(CH(2))Me(2)Si](2)N}(2)Sn resulted in an insoluble polymeric material. In a comparison reaction, [(Me(3)Si)(2)N](2)Sn was treated with OCS to yield Sn(4)(μ(4)-O)(μ(2)-OSiMe(3))(5)(η(1)-N═C═S). A combination of NMR and IR spectroscopy, mass spectrometry, and single crystal X-ray diffraction were used to characterize the products of each reaction. The oxygen atoms in the final products come from the facile cleavage of either CO(2) or OCS, depending on the reacting carbon dichalogenide.