The structure of thorikosite,a naturally occurring member of the bismuth oxyhalide group

Thorikosite, (Pb₃Sb_0.6As_0.4)(O₃0H)Cl₂, is a naturally occurring member of the bismuth oxyhalide group isostructural with LiBi₃O₄Cl₂. The space group isI4/mmm witha = 3.919(1)A?,c = 12.854(5)A?, andZ = 1. A crystal structure analysis showed complete solid solution of Pb²⁺, Sb³⁺, and As³⁺ on the single cation site and large atomic temperature factors indicative of pervasive structural disorder. The latter is due to the structural adjustments necessary to accommodate cations of very different sizes in the same site. Thorikosite is closely related to synthetic tetragonal PbSbO₂Cl through the coupled substitution Sb³⁺O^2? ? Pb²⁺(OH)^?.     

Polymer-assisted dispersion of single-walled carbon nanotubes in alcohols and applicability toward carbon nanotube/sol-gel composite formation

Single-walled carbon nanotubes (SWCNTs) were directly dispersed into various alcohols by sonicating the nanotubes in the presence of poly(4-vinylpyridine) (P4VP). Depending upon the alcohol, it was possible to disperse up to 0.3 g of SWCNTs per liter of alcohol using only 0.6 g of P4VP, and with solution stability greater than 6 weeks. Scanning electron microscopy of "bucky" paper prepared from the polymer-treated nanotubes revealed reduced bundle size compared to the corresponding untreated nanotube paper. Additionally, the applicability of the dispersion system in the formation of SWCNT/silica composites is demonstrated.     

Underquaternized anion exchange resins as covalent scavengers

The use of partially quaternized, chloromethylated polystyrene as a covalent scavenger of cholate ion in aqueous media has been demonstrated. The ability of such polymers to scavenge organic anions by covalent as well as by ionic means has important implications in the areas of medicinal and environmental chemistry, which are briefly discussed.     

A room-temperature neutron-diffraction study of NaH2PO4

The monoclinic crystal structure of NaH₂PO₄ at room temperature has been refined from neutron-diffraction measurements on a single-crystal sample and complied with the closely related structure of monoclinic KD₂PO₄. Attention is paid to the information obtained from these two structures about the geometry of hydrogen (deuterium) bonds ?2.6 A.     

Laser damage in optical materials at 1.06 μm

The high power and energy densities in a Q-switched laser beam modify the optical characteristics of a transmitting material and may ultimately cause damage. This paper reviews the mechanisms by which laser-induced damage occurs and summarizes the forms of such damage which are seen in practice. The experimental conditions for making accurate damage threshold measurements are set out, and the apparatus and procedures used in the present work are described. A summary of the laser-induced damage threshold measurements at 1.06 μm on a wide range of materials under the same conditions are presented and compared with other published data.     

Growth from the vapour by surface nucleation

The experimental conditions under which cadmium sulphide is grown from the vapour to form crystals having a (11.0) singular growth faces are calculated. This is done assuming that growth proceeds on these faces by one-dimensional surface nucleation. Calculations based on this assumption are compared with experimental observations on the habit of CdS, and the relationship between growth rate and supersaturation, and shown to be consistent with these.     

Nachweis und Bestimmung organischer S?uren

Ohne Zusammenfassung