Publications

ChemInform Abstract: Reticular Chemistry of Metal—Organic Polyhedra

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Progress and Challenges in K-Ar and⁴⁰Ar/³⁹Ar Geochronology

K-Ar and more recently the 40 Ar/ 39 Ar variant are well established dating methods. The 40 Ar/ 39 Ar method requires irradiation with neutrons, posing some complications that are greatly outweighed by the benefits. The 40 Ar/ 39 Ar method is particularly powerful due to the availability of internal reliability criteria, the ability to analyze single crystals, and the amenability of the analyses to automation. 40 Ar/ 39 Ar dating has the capability for unsurpassed precision and is applicable to the broadest range of geologic environments and time scales of any radioisotope dating technique. For chronostratigraphic applications, 40 Ar/ 39 Ar is most important in the Cenozoic, becoming progressively less useful into the early Phanerozoic due to alteration and loss of radiogenic argon. Precision and accuracy of 40 Ar/ 39 Ar dating have been improved considerably in recent years, but an uncertainty of about 1% in the decay constant for 40 K, probably mainly in the electron capture decay branch, still limits accuracy at about this level. Inconsistent use of standards (neutron fluence monitors) and attribution of variable ages to standards is still a source of confusion, but straightforward recalculation procedures can overcome the underlying problems provided that appropriate standards are used.

Optical properties and electronic structure of InN and In-rich group III-nitride alloys

Characterization of mechanical degradation in an all-solid-state battery cathode

In this work, we visualize and quantify the microstructure evolution in the composite electrode after solid-state battery (SSB) cycling. The observed severe mechanical degradation highlights the importance of mechanical considerations in SSB design.

Iugs–IUPAC Recommendations and Status Reports on the Half-Lives of 87Rb, 146Sm, 147Sm, 234U, 235U, and 238U

The IUPAC–IUGS joint Task Group “Isotopes in Geosciences” (TGIG) has evaluated the published literature on the half-lives of six long-lived, geologically relevant radioactive nuclides. Where conflicting literature estimates are present, it is necessary to first identify any systematic bias in accordance with metrological traceability and to exclude the biased estimates from further consideration. The TGIG recommends three robust half-life estimates: 49.61 ± 0.16 Ga for 87Rb, corresponding to a decay constant λ(87Rb) = (1.3972 ± 0.0045) × 10−11 a−1; 106.25 ± 0.38 Ga for 147Sm, and a corresponding decay constant λ(147Sm) = (6.524 ± 0.024) × 10−12 a−1; 4.4683 ± 0.0096 Ga for 238U, i.e. a decay constant λ(238U) = (1.55125 ± 0.00333) × 10−10 a−1. All cited uncertainties have a coverage factor k = 2. For other radionuclides of Sm and U, no unambiguous consensus value can be endorsed at present by TGIG, which limits its evaluation to a status report highlighting unaccounted-for potential sources of bias. The improved repeatability of mass spectrometric measurements has revealed systematic bias effects that had been dismissed as subordinate in the past. These issues can only be resolved by future dedicated investigations.

Photonic Band Structure

Gate-dependent pseudospin mixing in graphene/boron nitride moiré superlattices

The pressure distribution along stone columns in soft clay under consolidation and foundation loading

The mechanism whereby foundation loading is transmitted through the column has received little attention from researchers. This paper reports on some interesting findings obtained from a laboratory-based model study in respect of this issue. The model tests were carried out on samples of soft clay, 300 mm in diameter and 400 mm high. The samples were reinforced with fully penetrating stone columns, of three different diameters, made of crushed basalt. Four pressure cells were located along each stone column. The 60 mm diameter footing used in the model was supported on a clay bed reinforced with a stone column and subjected to foundation loading under drained conditions. The results show that the dissipation of excess pore water pressure developed during the initial application of total stresses, when the foundation was subjected to no loading, generated considerable stresses within the column, and that this was directly attributable to the development of negative skin friction. The pressure distributions in the column during foundation loading showed some complex behaviour.

The Oxidation of Hydrogen on Oxidized Platinum

Abstract not Available.

Clean energy demand must secure sustainable nickel supply

Seasonal and diurnal variation in the co2 flux and co2—water flux ratio of alfalfa

On the Formation of Voids in Anodic Oxide Films on Aluminum

A mechanism is proposed for the formation of voids at triple points between grains in the anodic oxide formed on aluminum and for the growth of porous films. The proposed mechanism involves the condensation of cation and/or metal vacancies below regions in the barrier film (triple points) that are characterized by high cation vacancy diffusivity, due to the high degree of lattice disorder. Vacancy condensation causes local decohesion of the barrier layer from the substrate, thereby inhibiting the growth of the layer into the metal in these regions. The lower film growth rate, relative to the surrounding areas, accounts for the observation that the voids subtend protrusions of the metal into the film. Periodic detachment of the voids, followed by nucleation and growth of new voids at the apex of the protrusions, accounts for decoration of the barrier layer with voids as well as for the formation of the hexagonal array of pores, when aluminum is anodized in some electrolytes.

Solution‐Processed, Molecular Photovoltaics that Exploit Hole Transfer from Non‐Fullerene, n‐Type Materials

Solution-processed organic photovoltaic devices containing p-type and non-fullerene n-type small molecules obtain power conversion efficiencies as high as 2.4%. The optoelectronic properties of the n-type material BT(TTI-n12)2 allow these devices to display high open-circuit voltages (>0.85 V) and generate significant charge carriers through hole transfer in addition to the electron-transfer pathway, which is common in fullerene-based devices. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An n-SIPOS: p-SIPOS homojunction and a SIPOS-Si-SIPOS double heterostructure

For maximal performance, solar cells should resemble semiconductor lasers; i.e. they should be constructed in the form of a double heterostructure. This configuration is also sometimes called ''minority carrier mirrors''. We have found rather good performance in SIPOS-crystalline silicon-SIPOS double heterostructures as well as in a p-n homojunction made entirely of SIPOS. This sheds some light on the truly outstanding performance of the n/sup +/-SIPOS: Si heterojunction which has a J /sub o/ = 10/sup -14/ Amps/cm/sup 2/. It has been recognized for some time that the structure of an ideal solar cell should resemble that of a semiconductor laser. The solar cell should be built in the form of a double heterostructure. In this configuration, a narrow bandgap active layer is sandwiched between two wide bandgap layers of opposite doping. The wide bandgap materials may be called ''minority carrier mirrors'' although this term is more frequently applied to high-low homojunctions at the rear of solar cells.

Fluorescent probes for nitric oxide and hydrogen peroxide in cell signaling

Plasmid [omega]-3 Fatty Acid Desaturase cDNA from Ricinus communis

Chloroplast membrane lipids are rich in the polyunsaturated fatty acids hexadecatrienoic acid and a-linolenic acid.

Optical properties of microalgae for enhanced biofuels production

Research seeks to alter the optical characteristics of microalgae in order to improve solar-to-biofuels energy conversion efficiency in mass culture under bright sunlight conditions. This objective is achieved by genetically truncating the size of the light-harvesting chlorophyll arrays that serve to absorb sunlight in the photosynthetic apparatus.

The potential of remotely sensed phenology as indicator of structure and function in wetland ecosystems