In the Bayer process of preparing alumina from bauxite small molecular weight compounds such as C 2 -C 6 , mono-, di-, and trialiphatic carboxylic acids which have hydroxy substituents are formed from a humic material. While involatile as anions under refinery conditions, upon acidification they become volatile and can be lost either in processing or in workup of process liquors in the laboratory. The origin of these organics is unknown; however, this paper shows that they are directly derived from the water-soluble (mainly carbohydrate) fraction in the vegetation that is dissolved with the bauxite in preparing process liquors. Glucitol is shown to be a particularly stable carbohydrate to digestion and may, therefore, play an important role in Bayer poisoning processes.

Mobile learning technologies are spreading rapidly in educational institutions throughout the world. Although research findings concerning the efficacy of mobile technologies for improving student outcomes are generally promising, there are still significant gaps in the research literature, particularly data from direct observational studies. This empirical investigation focused on how students made use of tablet devices and digital pens for learning Chemistry in an undergraduate university course. Observational data in the form of videos and static images, as well as, interview responses, were the main sources of data collected for the study. Activity theory was employed as the guiding theoretical framework to analyse and interpret the data. Several themes emerged from the data analyses, including the affordances of digital pen technology for facilitating reflective thinking, flexibility, peer collaboration, emerging learning and focused learning. It was also found that the use of these mobile technologies was contextualized, dependent on individual differences, and had challenges, for example, there was limited synchronicity between the operational design of the mobile devices and natural human movement. One of the main implications of the research is that when higher education institutions consider the potential benefits and challenges associated with mobile technologies they should take account of the interactions that occur between components within a system including, students, technological devices, and emerging learning processes.

The effect of annealing at 1400 1C in argon on the bond structure of graphite ball milled for 100 h at 400 rpm in polar (water) and in non-polar (n-dodecane) liquids was investigated primarily by near-edge X-ray absorption fine structure spectroscopy (NEXAFS) and transmission electron microscopy (TEM). Carbon K-edge NEXAFS allows the distortion of bonds in the hexagonal lattice to be investigated. It is shown that in-plane sp 2 bonds are strained and distorted after ball milling because sp 3 bonds are introduced. Not surprisingly, annealing of the milled product restores sp 2 bonds but at the same time, coiling and formation of tube-like structures takes place. It is well established that graphite is not formed on annealing, and hence the results shown here demonstrate that the loss of sp 3 carbons on annealing must proceed via a different mechanism by which they are formed by milling. r

Both solution and solid state Nuclear Magnetic Resonance (NMR) spectroscopic techniques have been used to determine differences in commercially available condoms. Whilst solid state NMR is useful for determining the polymer backbone, it is not useful for forensic analysis due to the commonality of the latex condom. However solution NMR spectra obtained following a simple extraction procedure using hexane, provides a fingerprint of the additives in the lubricants. Following the development of a flow chart, basing decisions on the presence of particular peaks present in the solution spectra, 33 of 38 condoms could be individualized. Samples were also analyzed after having the lubricant manually removed and soaking the condom in water for 3 to 24 h. These experiments were performed to simulate a case of the sample having been used and disposed of by flushing down the toilet, as may be experienced in a case of a sexual assault. The results indicated that the only significant water soluble component was polyethylene glycol. The overall results suggest that the method developed may be a quick and useful technique in characterizing condoms. The information obtained can be used to provide associative evidence between suspect and crime, and so be useful in sexual assault cases.

This study explored reductions in tissue nitrogen concentration ([N]) at elevated CO2 concentrations ([CO2]), and changes in plant water and N uptake. Eucalyptus saligna Sm. seedlings were grown under three [CO2] levels (preindustrial (280 μL L–1), current (400 μL L–1) or projected (640 μL L–1)) and two air temperatures (current, (current + 4°C)). Gravimetric water use, leaf gas exchange and tissue dry mass and %N were determined. Solid-state 15N-NMR spectroscopy was used for determining the partitioning of N chemical groups in the dry matter fractions. Water use efficiency (WUE) improved with increasing [CO2] at ambient temperature, but strong leaf area and weak reductions in transpiration rates led to greater water use at elevated [CO2]. High temperature increased plant water use, such that WUE was not significantly stimulated by increasing [CO2] at high temperature. Total N uptake increased with increasing [CO2] but not temperature, less than the increase recorded for plant biomass. Tissue [N] decreased with rising [CO2] and at high temperature, but N use efficiency increased with rising [CO2]. Total N uptake was positively correlated with total water use and root biomass under all treatments. Growth [CO2] and temperature did not affect the partitioning of 15N among the N chemical groups. The reductions of tissue [N] with [CO2] and temperature were generic, not specific to particular N compounds. The results suggest that reductions in tissue [N] are caused by changes in root N uptake by mass flow due to altered transpiration rates at elevated [CO2] and temperature.

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