13C NMR spectra of tricyclo[4.2.1.02,5]nonanes and tetracyclo[5.4.1.02,6.08,11]dodecanes

The ¹³C NMR spectra of tricyclo[4.2.1.0^2,5]nonanes and tetracyclo[5.4.1.0^2,6.0^8,11]dodecanes and their dimethyl derivatives were measured to demonstrate the four-membered ring annelation effects on the bicyclo[2.2.1]heptane skeleton, and the steric δ-syn effects of the methyl groups attached to the four-membered ring on the bridge carbons in these systems.     

Statistics of Gaussian Speckles with Enhanced Fluctuations

Some first-order statistics of speckle fields obeying the complex Gaussian probability density are investigated with the special emphasis on a possibility for the speckle contrast to exceed unity. It is shown that such enhanced fluctuations of speckle fields are generated when the probability density of the complex amplitude is non-circular with the vanishing mean. This means that Gaussian speckles having the contrast of unity are not necessarily fully developed speckles. Some practical situations producing such enhanced fluctuations in speckle fields are discussed.     

Selective oxidation of methane to formaldehyde over antimony oxide-loaded catalyst

A possibility of antimony oxide as a catalyst for the selective oxidation of methane with oxygen to formaldehyde was investigated. The activity measurement was carried out at an atmospheric pressure and at 873 K, where the homogeneous gas-phase reaction was negligible. Oxidized diamond (O-Dia)-supported antimony oxide catalyst produced 1.3 mmol h⁻¹ g-cat⁻¹ of formaldehyde with a formaldehyde selectivity of 23%. On the other hand, SiO₂ supported antimony oxide catalyst exhibited negligible catalytic activity. XRD and UV–vis analyses revealed that -Sb₂O₄ was formed on the oxidized diamond while Sb₆O₁₃ was formed on SiO₂. Selective oxidation of methane to formaldehyde seemed to proceed on -Sb₂O₄ with moderate activity and selectivity to formaldehyde, via a redox cycle of -Sb₂O₄ and Sb₂O_4−x. On the other hand, Sb₆O₁₃ on SiO₂ was stable under the reaction conditions and the selective oxidation occurred only slightly.     

Quality control of PET radiopharmaceuticals by high‐performance liquid chromatography with tris(2,2′‐bipyridyl)ruthenium(II) electrogenerated chemiluminescence detection

A highly sensitive reversed‐phase liquid chromatographic (HPLC) method was investigated to analyze a range of positron emission tomography (PET) radiopharmaceuticals using electrogenerated chemiluminescence (ECL) detection. ECL is based on the reaction of PET molecules with tris(2,2′‐bipyridyl)ruthenium(III) [Ru(bpy)₃³⁺], which is generated through the on‐line electro‐oxidation of Ru(bpy)₃²⁺. In 21 different radiopharmaceuticals studied, 18 compounds could be detected with detection limits (signal‐to‐noise ratio = 3) of 0.12–72 ng/mL per 20 μL injection. Sufficient reproducibility and linearity were obtained for the quantitative determination of PET molecules in pharmaceutical fluid. This method could be successfully applied to quality control tests of PET radiopharmaceuticals with ultra‐high specific radioactivity. Copyright © 2009 John Wiley & Sons, Ltd.     

Gelation of colloidal crystals without degradation in their transmission quality and chemical tuning

A single-domain colloidal crystal with high transmission quality, prepared by a shear-induced process, was fixed as a hydrogel film by photopolymerization. Upon gelation, the original optical quality was almost perfectly preserved. By replacing the solvent, the gelled crystal could be converted to smaller lattice constant crystals without significant degradation in its transmission characteristics. The conversion results in a stop-band wavelength coverage across the entire visible light range.     

Microanalytical Techniques Applied to Phase Identification and Measurement of Solute Redistribution at the Solid/Liquid Interface of Frozen Fe-4.3Ni Doublets

 A Fe-4.3Ni alloy has been solidified directionally by using the Bridgman system. The solidification conditions were chosen to obtain an oriented cellular structure of δ-ferrite. These are: a positive temperature gradient of about 60 K/cm and a growth rate of 6.6 μm/s. A change in these conditions can lead either to the formation of austenite or to the competitive growth of δ-ferrite/γ-austenite. The solid/liquid interface of δ-ferrite cells has been frozen and double instability has been revealed at the tip of the cells. The instability is described as the first harmonic wave of fundamental undulation, which appeared at the formerly planar solid/liquid interface. This means that a doublet structure is formed only with the imposed specific conditions of solidification. The Ni-solute redistribution after back-diffusion has been measured across the δ-ferrite doublet. Results of energy dispersive X-ray (EDX) measurements on the distribution of Ni and Fe correspond well to the theoretical prediction for redistribution developed especially for oriented structure formation (two dimensional solidification). Additionally, electron backscattered diffraction from the bulk Fe-4.3Ni alloy sample allowed us to determine the local structure, i.e. the distribution of single crystallite orientations in the microstructure. A unique correlation between fluctuations of the Ni-solute redistribution and crystalline orientations in the δ-ferrite doublets has been demonstrated. Moreover, a relationship between geometrical asymmetry of the doublets and solute redistribution has also been found.