Reaction-times of hearing-impaired children to acoustic stimuli of different sensation levels

This paper discusses a study to determine the relation between sensation level and response time to acoustic stimuli.

Synthesis of S-linked carbohydrate analogues via a Ferrier reaction

In this work, the synthetic utility of the Ferrier reaction to access S-linked disaccharides and S-linked glycoamino acids has been probed. Significantly, entry to a range of 1,4- and 1,6-S-linked disaccharides has been achieved using glycals derived from glucose and galactose, and sulfur containing coupling partners derived from methyl α-d-glucopyranoside. Access to S-linked glycoamino acids and glycopeptides has also been achieved using protected cysteine and homocysteine coupling partners within the Ferrier reaction. Functionalisation of the Ferrier products, for example, via dihydroxylation using OsO4 or amino acid coupling, and deprotection of the targets have also been achieved. In this way, entry to materials of interest as mimics of biologically interesting disaccharides and glycopeptides has been realised, including targets derived from rare sugars such as talopyranose and gulopyranose.

Functional disconnection of a prefrontal cortical-dorsal striatal system disrupts choice reaction time performance: implications for attentional function

This series of experiments investigated the role of a prefrontal cortical-dorsal striatal circuit in attention, using a continuous performance task of sustained and spatially divided visual attention. A unilateral excitotoxic lesion of the medial prefrontal cortex and a contralateral lesion of the medial caudate-putamen were used to "disconnect" the circuit. Control groups of rats with unilateral lesions of either structure were tested in the same task. Behavioral controls included testing the effects of the disconnection lesion on Pavlovian discriminated approach behavior. The disconnection lesion produced a significant reduction in the accuracy of performance in the attentional task but did not impair Pavlovian approach behavior or affect locomotor or motivational variables, providing evidence for the involvement of this medial prefrontal corticostriatal system in aspects of visual attentional function.

Interfacial structure of wild-type and mutant forms of puroindoline-b bound to DPPG monolayers

The interaction of wild-type puroindoline-b (Pin-b+) and two mutant forms having single residue substitutions (G46S or W44R) with L-alpha-dipalmitoylphosphatidyl-dl-glycerol (DPPG) as a Langmuir monolayer at the air/water interface was investigated by neutron reflectivity (NR) and Brewster angle microscopy (BAM). NR profiles were fitted using a three-layer model to enable differences in penetration of protein between the lipid headgroup and acyl regions to be determined. The data showed similar surface excesses for each of the three proteins at the interface; however, it was revealed that the depth of penetration of protein into the lipid region differed for each protein with Pin-b+ penetrating further into the acyl region of the lipid compared to the mutant forms of the protein that interacted with the headgroup region only. BAM images revealed that the domain structure of the DPPG monolayers was disrupted when Pin-b+ adsorption had reached equilibrium, suggesting protein penetration had led to compression of the lipid region. In contrast, the domain structure was unaffected by the W44R mutant, suggesting no change in compression of the lipid region and hence little or no penetration of protein into the lipid layer.

Reactive uptake coefficients for heterogeneous reaction of N2O5 with submicron aerosols of NaCl and natural sea salt

The kinetics of uptake of gaseous N2O5 on submicron aerosols containing NaCl and natural sea salt have been investigated in a flow reactor as a function of relative humidity (RH) in the range 30-80% at 295±2K and a total pressure of 1bar. The measured uptake coefficients, γ, were larger on the aerosols containing sea salt compared to those of pure NaCl, and in both cases increased with increasing RH. These observations are explained in terms of the variation in the size of the salt droplets, which leads to a limitation in the uptake rate into small particles. After correction for this effect the uptake coefficients are independent of relative humidity, and agree with those measured previously on larger droplets. A value of γ=0.025 is recommended for the reactive uptake coefficient for N2O5 on deliquesced sea salt droplets at 298K and RH>40%.