The preparation and structure of 1,4,5,6,7,7-hexachloro-2-endo-ferrocenylhydroxymethyl-3-endo-hydroxymethyl-5-norbornene

The crystal structure of a novel ferrocene derivative with potential flame-retardant/smoke-suppressant activity, 1,4,5,6,7,7-hexachloro-2-endo-ferrocenyl-hydroxymethyl-3-endo-hydroxymethyl-5-norbornene, has been determined. Some of the carbon–carbon bonds within the chlorendic residue are unusually long, and there is no interaction between the hydroxyl groups and the iron atom. There is evidence of intramolecular hydrogen bonding between the two hydroxyl groups.     

Kinetically inert transition metal complexes that reversibly bind to DNA

Transition metal complexes that reversibly bind to DNA have been studied for almost 30 years. In the last few years a variety of new systems have been developed, employing a range of metal ions and ligand architectures. In many cases, high affinity binding and specific selectivities have been observed. These complexes display properties that make them attractive as probes of DNA structure and function, suggesting that they may find a r?le as prototypical tools for a spectrum of applications, from basic molecular biology to medicine. This review presents an overview of some of the structures and properties of such complexes.     

Observation of apigenin anionic clusters in the gas phase

The ubiquity and favorable medicinal properties of flavonoids make essential the determination of flavonoid levels in various matrices. While developing a liquid chromatography/tandem mass spectrometry method for the analysis of the flavonoid, apigenin, anionic oligomers and nitrate- and chloride-bound clusters of this compound were observed. Tandem mass spectrometry of these oligomers and cluster ions showed the cleavage of apigenin molecules from the precursor. The observation of these cluster ions shows the possibility of post-column derivatization techniques to enhance specificity in analysis. Copyright 2000 John Wiley & Sons, Ltd.     

Liquid chromatographic determination of hyoscine (scopolamine) in urine using solid phase extraction.

A sensitive method for the determination of hyoscine (scopolamine) in urine is described. After concentration and "clean-up" on C18 and CN solid phase extraction columns, hyoscine was quantified by high performance liquid chromatography with coulometric detection (oxidation at +0.9 V). The limit of detection was 5 ng per sample and the precision for 5 mL samples containing 2 ng/mL was 12.3%. The method was applied to urine samples collected from 12 volunteers wearing Scopoderm TTS patches. The mean excretion rate of unmetabolized hyoscine was 0.45 micrograms/h and 87% of the total hyoscine was present as conjugates. Apohyoscine (aposcopolamine) was identified as a urinary metabolite. The significance of this with regard to hyoscine assays is discussed.     

Observation of Na(+)-bound oligomers of quercetin in the gas phase

While developing a liquid chromatography/tandem mass spectrometry method for the analysis of the flavonoid quercitin, it was observed that quercetin (3,3',4',5,7-pentahydroxyflavone) exhibited clustering in both the positive and negative ion mode. Two series of positive ion clusters were observed; the first series corresponds to singly charged [2M + Na](+) at m/z 627.2 to [13M + Na](+) at m/z 3947.5, while the second series corresponds to doubly charged [7M + 2Na](2+) at m/z 1080.4 to [25M + 2Na](2+) at m/z 3798.5. In the negative ion mode, the behavior of quercetin parallels that of apigenin (4',5,7-trihydroxyflavone) in that [M + NO(3)](-), [2M + NO(3)](-), and [3M + NO(3)](-) were observed at m/z 364.1, 666.0, and 968.9, respectively; in addition, quercitin clusters with chloride ions ([2M + Cl](-) at m/z 638.9 and [3M + Cl](-) at m/z 940. 9) were observed. The results of tandem mass spectrometric examination of several cluster ions are reported.     

Expressivity in chain-based modal logics

We investigate the expressivity of many-valued modal logics based on an algebraic structure with a complete linearly ordered lattice reduct. Necessary and sufficient algebraic conditions for admitting a suitable Hennessy–Milner property are established for classes of image-finite and (appropriately defined) modally saturated models. Full characterizations are obtained for many-valued modal logics based on complete BL-chains that are finite or have the real unit interval [0, 1] as a lattice reduct, including ?ukasiewicz, Gödel, and product modal logics.     

Endogenous Nanoparticles Strain Perovskite Host Lattice Providing Oxygen Capacity and Driving Oxygen Exchange and CH4 Conversion to Syngas

Particles dispersed on the surface of oxide supports have enabled a wealth of applications in electrocatalysis, photocatalysis, and heterogeneous catalysis. Dispersing nanoparticles within the bulk of oxides is, however, synthetically much more challenging and therefore less explored, but could open new dimensions to control material properties analogous to substitutional doping of ions in crystal lattices. Here we demonstrate such a concept allowing extensive, controlled growth of metallic nanoparticles, at nanoscale proximity, within a perovskite oxide lattice as well as on its surface. By employing operando techniques, we show that in the emergent nanostructure, the endogenous nanoparticles and the perovskite lattice become reciprocally strained and seamlessly connected, enabling enhanced oxygen exchange. Additionally, even deeply embedded nanoparticles can reversibly exchange oxygen with a methane stream, driving its redox conversion to syngas with remarkable selectivity and long term cyclability while surface particles are present. These results not only exemplify the means to create extensive, self‐strained nanoarchitectures with enhanced oxygen transport and storage capabilities, but also demonstrate that deeply submerged, redox‐active nanoparticles could be entirely accessible to reaction environments, driving redox transformations and thus offering intriguing new alternatives to design materials underpinning several energy conversion technologies.     

Cathodoluminescence from gallium nitride implanted with arsenic or phosphorus

Phosphorus and arsenic impurities have been introduced into single crystal thin films of gallium nitride by ion implantation. New luminescence bands are observed at 2.85 eV for the phosphorus implant and at 2.58 eV for the arsenic implant. There is some evidence for charge carrier compensation. A band at 2.2 eV is associated with implantation damage and high temperature annealing.     

The refractive index correction to the radiative rate constant in fluorescence lifetime measurements

The dependence of fluorescence decay times upon the refractive index of the solvent has been measured in two types of system: (a) in a single solvent at different temperatures, (b) in different solvents. The results are consistent with an n² dependence of the radiative rate constant, as has been predicted theoretically.