Magnetization and Curie Temperature of Ilmenite–Hematite Ceramics

The morphology, structure, and magnetic properties of the magnetic semiconductor ceramic Ilmenite–Hematite (IH), (1− x )FeTiO₃– x Fe₂O₃, were studied as a function of the composition x . The magnetic ordering temperatures that we observed were consistently higher than those reported previously and were, for most of the composition range, above room temperature. We rule out the formation of Fe clusters as the origin of the magnetic properties. These magnetic properties of IH ceramics, in combination with their semiconducting characteristics, render them promising for spin-electronic applications.     

Hyperactive and hypoxic children: Signal detection, sustained attention, and behavior.

Two parameters from signal detection theory—perceptual sensitivity and decision criterion cutoff scores—were used in the analysis of vigilance performance of 30 hyperactive (mean age 8.5 yrs), 30 hypoxic (mean age 9 yrs), and 47 normal (mean age 8.8 yrs) children. Signal detection analyses of 3 Continuous Performance Test conditions indicated that with increasing age, Ss obtained significantly more hits, fewer false alarms, higher perceptual sensitivity, and responded with greater caution. Overall deficits in signal discrimination (perceptual sensitivity level) were obtained for both the hyperactive and hypoxic Ss when compared to normal age-mates. Whereas the hypoxic Ss demonstrated additional decrements in sustaining attention (sensitivity decrement over time), the hyperactive Ss were impaired by low-response caution, reflecting difficulty inhibiting impulsive responses. Possible differences in hyperactive sample characteristics across studies and time-related recovery factors following hypoxia are discussed. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The electrical conductivity of cast Al−Si alloys in the range 2 to 12.6 wt pct silicon

The changes in electrical conductivity of cast Al−Si alloys, in the range of 2 to 12.6 wt pct silicon due to strontium additions (0.03 wt pct) have been investigated and explained in terms of variations in microstructure. The strontium-containing alloys exhibited a higher conductivity than alloys with no strontium, and this conductivity difference increased as the silicon and magnesium contents were increased and the solidification rate was decreased. It has been demonstrated that this difference is due to changes in microstructural features of the eutectic silicon upon modification.     

Interaction of molecules with molybdenum disulphide catalysts: An experimental and molecular graphics study. Isoprene

The interaction of isoprene with molybdenum disulphide has been studied by computer-assisted modelling of the binding of the molecule at active sites. Possible structures of intermediate-active-site complexes were evaluated by the method of molecular mechanics. For isoprene hydrogenation the preferred catalytic sites, according to energy minimisation calculations, proved to be corner molybdenum atoms having threefold unsaturation. This conclusion agrees with deductions from experimental studies of isoprene hydrogenation. The modelling studies are valuable for revealing the steric relationships between active sites and substrate molecules, for calculating the most likely structures, and for revealing non-bonded interactions.     

Phagocyte dysfunction in common variable immune deficiency

The history of a 13-year old boy is reported who suffered from frequent bacterial, enteroviral, and protozoal infections since late infancy. A decrease in the serum levels of IgG2, IgG3, IgA, a neutrophil dysfunction, and a partial cellular immune deficiency could be demonstrated. A deficiency of folic acid produced a pancytopenia which enhanced the patient's susceptibility to infections. The combined substitution of gammaglobulins and folic acid only was able to break this vicious cycle.     

The development of the globally harmonized system (GHS) of classification and labelling of hazardous chemicals

The hazards of chemicals can be classified using classification criteria that are based on physical, chemical and ecotoxicological endpoints. These criteria may be developed be iteratively, based on scientific or regulatory processes. A number of national and international schemes have been developed over the past 50 years, and some, such as the UN Dangerous Goods system or the EC system for hazardous substances, are in widespread use. However, the unnecessarily complicated multiplicity of existing hazard classifications created much unnecessary confusion at the user level, and a recommendation was made at the 1992 Rio Earth summit to develop a globally harmonized chemical hazard classification and compatible labelling system, including material safety data sheets and easily understandable symbols, that could be used for manufacture, transport, use and disposal of chemical substances. This became the globally harmonized system for the Classification and Labelling of Chemicals (GHS). The developmental phase of the GHS is largely complete. Consistent criteria for categorising chemicals according to their toxic, physical, chemical and ecological hazards are now available. Consistent hazard communication tools such as labelling and material safety data sheets are also close to finalisation. The next phase is implementation of the GHS. The Intergovernmental Forum for Chemical Safety recommends that all countries implement the GHS as soon as possible with a view to have the system fully operational by 2008. When the GHS is in place, the world will finally have one system for classification of chemical hazards.     

Train drivers' sleep and alertness during short relay operations

Within Australia, there has been a recent expansion of relay working operations. To address concerns about the amount of sleep obtained by drivers in relay vans, and potential deficits in alertness associated with relay work, the current study assessed the sleep behaviour and alertness of 15 train drivers working short (<48 h) relay operations. In total, drivers obtained 8-12h of sleep during the relay trip (which took approx 40 h). Overall, they reported that they felt more alert following each sleep period. Drivers were able to sustain attention during the 10-min vigilance tasks administered before and after each shift. These findings suggest that the amount of sleep obtained in crew vans during short relay operations is sufficient to maintain alertness during the trip. They also emphasise the importance of scheduling shifts to maximise the number of sleep opportunities that occur between 2200 and 0700 h.     

Cannabis: Review of behavioral effects in animals.

Reviews research studies concerning the action of cannabis and its derivatives on numerous aspects of animal behavior. These aspects include spontaneous activity; escape and avoidance behavior; schedule-controlled behavior; state-dependent learning; miscellaneous appetitively and nonappetitively motivated behavior; food and water intake; and aggression. Disparate findings are discussed and attributed mainly to differences in dosage and experimental procedure. It is suggested that in a number of instances the effects of cannabis are similar to those of anticholinergic drugs. (4 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)