Nanomechanical properties of commercial float glass

The float process produces flat glass with a tin-rich surface due to contact with the molten metal bath. The incorporation of tin into the glass network is expected to modify the mechanical properties of the surface and the relative durability of the two sides of the material. In this work nanoindentation was used to evaluate the elastic modulus and hardness of a 2 mm thick commercial float glass. The near-surface elastic modulus (depths < 400 nm) of both sides of the glass was elevated by up to 10%, and could not be attributed solely to the presence of tin. However, slight differences in hardness (<10%) between the air and tin sides of the float glass were observed. These results suggest that tin may alter the flow properties of the glass, but the elastic modulus changes are masked by other structural and chemical differences between the air and tin sides of the float glass.     

Identification of archaeological ivories using FT-Raman spectroscopy

FT-Raman spectroscopy has been used successfully for the non-destructive identification of modern ivories and is evaluated here for the identification of osseous materials from archaeological sites. Results on archaeological ivories are reported and the problems faced in matching FT-Raman spectra to standards for the validation of these materials are highlighted. Archaeological specimens of different dates, provenance and taphonomic history, including both conserved and unconserved items, have been analysed.     

Application of portable Raman spectroscopy and benchtop spatially offset Raman spectroscopy to interrogate concealed biomaterials

In this paper, we demonstrate the ability of portable Raman spectroscopy and benchtop spatially offset Raman spectroscopy (SORS) techniques to rapidly identify real and fake ivory samples. Both techniques were able to identify exposed genuine from fake ivory samples. In contrast to conventional Raman spectroscopy, SORS was, in addition, able to identify ivory concealed by plastics, paints, varnishes and cloth. Application of the SORS technique allows the interrogation of biomaterial samples through materials in which conventional Raman spectroscopic instrumentation cannot penetrate. Copyright © 2009 John Wiley & Sons, Ltd.     

Thermal degradation of flame-retardant compounds derived from castor oil

Castor oil is a non-edible plant oil produced in a large quantity annually. It is a triglyceride of primarily (approximately 90%) ricinoleic acid. The acid residues contain both a hydroxyl group and a double bond which permit ready functionalization. The hydroxyl group may be converted to phosphorus esters of varied structure while the unsaturation readily undergoes addition of bromine. Derivatives of castor oil containing phosphorus, bromine, or phosphorus and bromine have been prepared and fully characterized using spectroscopic and thermal methods. The thermal stability and mode of degradation for these compounds have been assessed using thermogravimetry and infrared spectroscopy. The primary mode of degradation for the phosphorus esters is elimination of the corresponding phosphorus acid (phosphates more readily than phosphonates). Brominated castor oil undergoes thermally induced dehydrobromination at relatively modest temperatures and this promotes dehydration (at temperatures well below that required for dehydration of unmodified castor oil). Brominated phosphorus esters of castor oil undergo degradation initiated by dehydrobromination.

     

Nanoscale dendritic organoplatinum antitumor drugs

Organoplatinum compounds exhibit broad antitumor activity. Cisplatin [cis- dichlorodiammine platinum (II)] is the most prominent of this family and is currently the most prescribed cancer drug. It is widely used for the treatment of human testicular, ovarian, bladder, head and neck carcinomas. However, it is an extremely toxic compound and side effects such as nephrotoxicity and myelotoxicity are major drawbacks for its use in clinical applications. A way to combat the side effects associated with the administration of platinum drugs would be to generate a prodrug conjugate that, when present in the extracellular fluid, would slowly release active platinum species at a level below the threshold for side effects. Traditionally, linear hydrophilic polymers have been examined for potential application as carrier platforms for these drugs. The advent of dendrimers, which are highly branched macromolecules with precisely controlled nanoscale size, shape and end-group functionality, has provided an excellent opportunity to design and formulate novel multivalent time-release drug systems. For example, treatment of a generation 4.5 (carboxylate surface) poly(amidoamine) [PAMAM] dendrimer with diaquo(1,2-diaminocyclohexane) platinum(II) generates a nanoparticle with forty platinum moieties attached at the surface. This polymer-drug conjugate displays a very good release profile for the platinum species. Under physiological conditions about 80% of the platinum units are released over the first 24 hours. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A microfluidic mixer with grooves placed on the top and bottom of the channel

A new microfluidic mixer is presented consisting of a rectangular channel with grooves placed in the top and bottom. This not only increases the driving force behind the lateral flow, but allows for the formation of advection patterns that cannot be created with structures on the bottom alone. Chevrons, pointing in opposite directions on the top and bottom, are used to create a pair of vortices positioned side by side. Stripes running the width of the channel generate a pair of vertically stacked vortices. Computational fluid dynamics (CFD) simulations are used to model the behavior of the systems and provide velocity maps at cross-sections within the mixer. Experiments demonstrate the mixing that results when two segregated species enter the mixer side-by-side and pass through two cycles of the mixer (i.e., two alternating sets of four stripes and four chevrons).     

Raman spectroscopic analysis of cyanobacterial gypsum halotrophs and relevance for sulfate deposits on Mars

The Raman spectra of cyanobacterial species, Gloecapsa and Nostoc, in clear gypsum crystals from the Haughton Crater, Devon Island, Canadian High Arctic, site of a meteorite impact during the Miocene some 23 Mya, have been recorded using several visible and near-infrared excitation wavelengths. The best spectra were obtained using a green wavelength at 514.5 nm and a confocal microscope with an image footprint of about 2 micro in diameter and 2 micro theoretical depth. Raman biosignatures for beta-carotene and scytonemin were obtained for one type of colony and parietin and beta-carotene for another; chlorophyll was detected in both types of colony. The different combination of these radiation protectant biomolecules suggests that the two cyanobacterial colonies, namely Nostoc and Gloecapsa, are adopting different survival strategies in the system. Confocal spectroscopic probing of the gypsum crystals exhibited sufficient discrimination for the identification of the biomolecules through the gypsum crystal, in simulation of the detection of extant or extinct halotrophs. This supports the viability of Raman spectroscopic techniques for incorporation as part of the instrumentation suite of a robotic lander for planetary surface exploration for the detection of organisms inside sulfate crystals from previous hydrothermal activity on Mars.     

Phonational profiles of female professional singers and nonsingers

Measures of the SFF, vocal intensity, phonational range, and habitualpitch level are reported for 39 professional singer and 39 nonsinger females, who were divided into three age groups (young, middle, and old age), with the professionals further divided into sopranos and altos. Each read the “Rainbow Passage” and spoke extemporaneously, from which measures of the SFF and vocal intensity were calculated; phonational range and habitual pitch levels were also determined. No significant differences were noted between the reading and speaking tasks. The SFF and intensity levels were significantly higher for the professionals in comparison to the nonsingers, but only for certain age groups. Moreover, whereas the nonsinger SFF levels varied significantly as a function of age, those for the professional singers did not. Although trends occurred, no significant differences were found for the mean phonational range or habitual pitch levels when the professionals and nonsingers were compared.     

The reaction of diironenneacarbonyl with 1,2-cyclononadiene

1,2-Cyclononadiene reacts with Fe₂ (CO)₉ with dimerization of the allene ligand to give the bis(π-allylene)Fe₂ (CO)₆ complex, which ¹³C and ¹H NMR studies show to be fluxional.     

Amphitropic liquid crystals. Two lamellar phases in a surfactant containing thermotropic and lyotropic mesogenic groups

We have studied the lyotropic liquid-crystalline behaviour of cationic surfactants containing a potentially thermotropic moiety, a terminal cyanobiphenyloxy group. Both mono-alkyl and mid-chain substituted dialkyl surfactants have been examined using optical microscopy and NMR spectroscopy. Incorporation of the cyanobiphenyloxy group destabilizes the hexagonal and bicontinuous cubic phases, with only an extensive lamellar region being observed. For the dialkyl surfactant there is a range of compositions where two lamellar phases co-exist, one water-rich and the second surfactant-rich.