Rearrangement of 6,7-dithiabicyclo[3.1.1]heptane 6-oxides to a 7,8-dithia-6-oxabicyclo[3.2.1]octane catalyzed by montmorillonite K 10

Treatment of 2,2,4,4-tetramethyl-1,5-diphenyl-6,7-dithiabicyclo[3.1.1]heptane 6-endo-oxide ( 2 ) with Montmorillonitc K 10 in dichloromethane gave 2,2,-4,4-tetramethyl-1,5-diphenyl-7,8-dithia-6-oxabicyclo-[3.2.1]octane ( 6 ) (11%) with recovery of 2 (87%). Under similar reaction conditions, the 6-exo-oxide 7 and the sulfenate 6 gave a mixture of 6 (21%), 2 (67%), and 7 (9%) and a mixture of 2 (89%) and 6 (9%), respectively. These results indicate the relative thermodynamic stabilities of the three compounds to be 2 > 6 > 7 . PM3 calculations on these compounds showed the heats of formation (kcal/mol) to be in the following order: 6 (44.12783), 2 (57.46721), and 7 (59.37918). The driving force of this unusual 1,2-rearrangement of 2 and 7 to 6 would be the release of the ring strain of the bicyclo[3.1.1]heptane system of 2 and 7 by ring expansion.     

Fiber-optic distributed measurement of polarization beat length using slope-assisted Brillouin optical correlation-domain reflectometry

Optical Review - We demonstrate distributed measurement of the polarization beat length along single-mode optical fibers (SMFs) using slope-assisted Brillouin optical correlation-domain...     

Proton Conduction at High Temperature in High-Symmetry Hydrogen-Bonded Molecular Crystals of RuIII Complexes with Six Imidazole-Imidazolate Ligands

A new H-bonded crystal [Ru^III(Him)₃(Im)₃] with three imidazole (Him) and three imidazolate (Im⁻) groups was prepared to obtain a higher-temperature proton conductor than a Nafion membrane with water driving. The crystal is constructed by complementary N−H⋅⋅⋅N H-bonds between the Ru^III complexes and has a rare Icy-c* cubic network topology with a twofold interpenetration without crystal anisotropy. The crystals show a proton conductivity of 3.08×10⁻⁵ S cm⁻¹ at 450 K and a faster conductivity than those formed by only HIms. The high proton conductivity is attributed to not only molecular rotations and hopping motions of HIm frameworks that are activated at ∼113 K, but also isotropic whole-molecule rotation of [Ru^III(Him)₃(Im)₃] at temperatures greater than 420 K. The latter rotation was confirmed by solid-state ²H NMR spectroscopy; probable proton conduction routes were predicted and theoretically considered.     

Applications and extensions of cost curves to marine container inspection

Drummond and Holte introduced the theory of cost curves, a graphical technique for visualizing the performance of binary classifiers over the full range of possible class distributions and misclassification costs. In this paper, we use this concept to develop the Improvement Curve, a new performance metric for predictive models. Improvement curves are more user-friendly than cost curves and enable direct inter-classifier comparisons. We apply improvement curves to measure risk-assessment processes at Canada’s marine ports. We illustrate how implementing even a basic predictive model would lead to improved efficiency for the Canada Border Services Agency, regardless of class distributions or misclassification costs.     

Multi-moment advection scheme for Vlasov simulations

We present a new numerical scheme for solving the advection equation and its application to Vlasov simulations. The scheme treats not only point values of a profile but also its zeroth to second order piecewise moments as dependent variables, for better conservation of the information entropy. We have developed one-and two-dimensional schemes and show that they provide quite accurate solutions within reasonable usage of computational resources compared to other existing schemes. The two-dimensional scheme can accurately solve the solid body rotation problem of a gaussian profile for more than hundred rotation periods with little numerical diffusion. This is crucially important for Vlasov simulations of magnetized plasmas. Applications of the one- and two-dimensional schemes to electrostatic and electromagnetic Vlasov simulations are presented with some benchmark tests.     

Water‐ and Temperature‐Triggered Reversible Structural Transformation of Tetranuclear Cobalt(II) Cores Sandwiched by Polyoxometalates

Although stimuli‐responsive structural transformations of inorganic materials have attracted considerable attention because of their potential use as functional switchable materials, multinuclear metal cores frequently suffer from unexpected dissociation of metal cations and/or irreversible transformations into infinite structures. In this study, we describe the successful demonstration of the water‐ and temperature‐triggered reversible structural transformation between cubane‐ and planar‐type tetranuclear Co^II cores sandwiched by polyoxometalates. The arrangements and coordination geometries of the Co^II cations were interconverted by simple hydration and dehydration, resulting in the manipulation of the magnetic and optical properties of these compounds. Moreover, this system showed unique thermochromism through temperature‐dependent reversible structural interconversion.     

Chilling resistances of isolates of Pythium ultimum var. ultimum from the Arctic and Temperate Zones

Chilling resistances in moss pathogenic fungi, Pythium ultimum var. ultimum, from Longyearbyen, Svalbard (78 degree N, 15 degree E), located in the Arctic Zone and in the same isolates from Temperate Zone, were determined. Both strains had similar optimum growth temperatures. However, the strains from Svalbard could grow and survive at 0 - 5 degrees C. In addition, chilling treatment induced irregular mycelial morphology in the Arctic isolates. On the other hand, the isolates from Japan did not grow at temperatures below 5C and were destroyed after chilling stress (0 degree C for 3 days or at 4 degrees C for 1 week). The results suggested that isolates from Svalbard highly adapted to the severe spring condition in Polar environments.     

A fluorimetric determination of lecithin-cholesterol acyltransferase in blood plasma

A fluorimetric assay for lecithin-cholesterol acyltransferase in human plasma (normal and pathological) is described. The lowered cholesterol concentration in the enzyme reaction is determined fluorimetrically by using the cholesterol oxidase—peroxidase —tyramine system. The assay requires only 10 μl of plasma.     

On the miscibility gap in liquid bismuth-bismuth tribromide system

We have determined the location of the miscibility gap in liquid Bi-BiBr₃ system in the concentration-temperature, x?T, plane from the measurement of the electrical conductivity. The measurements have been done in the concentration range between 30.5 and 92.5 mol.% Bi and in the temperature range between 300 and 600°C. It is found that the temperature dependence of the conductivity of the mixture changes near the retrograde solubility region.     

Vector meson pole dominance in Jψ decays into mesons

The validity of the assumption that $\text{J}\text{ψ}$ decays into mesons proceed via ω, φ and ?⁰ poles followed by cascade decays is examined. $\text{Λ(}\text{J}\text{ψ}\text{→}\text{B}\text{π)}$ is well reproduced by using $\text{Λ(}\text{J}\text{ψ}\text{→ ?π), Λ(ω → ?π), Λ(}\text{B}\text{→ ωπ)}$ and the B → ωπ helicity structure. The structure of OZI-violating $\text{J}\text{ψ}\text{?}\text{V}{}^0$ transitions including the electromagnetic contribution is examined, and compared with the data on inclusive $\text{J}\text{ψ}$ decay.