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The adsorption of CO at 300 K on a reduced (H2, 713 K) 1% Au/Al2O3solid leads to the formation of a linear CO species adsorbed on the Au particles (denoted L1) characterized by an IR band at 2098 cm−1that slightly shifts to higher wavenumbers with the decrease in the coverage. For adsorption pressures Pa> 5 kPa, it is shown that there is a progressive reconstruction of the Au surface with the increase in the duration of the adsorption taleading to the disappearance of the Au sites associated with the L1 CO species and to the formation of new Au sites forming a linear CO species (denoted L2) characterized by an IR band at 2070 cm−1. The heats of adsorption of the two adsorbed species are determined as the function of their respective coverages by using the adsorption equilibrium infrared spectroscopy procedure previously developed. It is shown that they linearly decrease with the increase in their coverages from 62 to 43 kJ/mol for the L1 and from 100 to 50 kJ/mol for the L2 CO species at coverages 0 and 1, respectively. The values for the L1 CO species are consistent with a previous study on Au/TiO2and with literature data on model Au particles. The higher heat of adsorption of the L2 CO species as compared to that of L1 can be a driving force for the reconstruction of the Au particles. Moreover, it is shown that the L2 CO species presents a property similar to that of adsorbed CO species on reduced supported metal particles: the position of its IR band shifts to lower wavenumbers with the decrease in its coverage (the singleton is situated at 2025 cm−1). The sintering of the gold particles as a function of the number of pretreatment/reconstruction cycles leads to the detection of a third linear CO species characterized by an IR band at 2048 cm−1at 300 K with heats of adsorption of 80 and 60 kJ/mol at low and high coverages, respectively.

The heats of adsorption of linear and bridged CO species adsorbed on Ag0sites of a reduced 3% Ag/Al2O3catalyst and of the linear CO species on Agsites of the oxidized catalyst are determined as the function of their respective coverages by using the adsorption equilibrium infrared spectroscopy method previously developed. The evolutions of the intensities of the IR bands of each adsorbed species:  2045 cm-1and 2000 cm-1at 300 K, for the linear and bridged CO species, respectively, on Ag0sites of the reduced solid and 2168 cm-1for a linear CO species on Agsites of the oxidized solid are determined as a function of the adsorption temperature Ta, at a constant CO adsorption pressure PCO. This provides the evolutions of the coverages of each adsorbed CO species with Tain isobar conditions that give the individual heats of adsorption of the three adsorbed CO species at several coverages according to an adsorption model. The heats of adsorption of the linear and bridged adsorbed CO species on Ag0sites vary linearly with their coverages :  from E076 kJ/mol to E158 kJ/mol for the linear CO species and from E088 kJ/mol to E184 kJ/mol for the bridged CO species at coverages 0 and 1, respectively. Volumetric measurements indicate that the total amount of the adsorbed CO species represents a small fraction of the superficial sites of the reduced Ag particles suggesting that they are adsorbed on defect sites. The heat of adsorption of the linear CO species on the Agsites linearly varies with its coverage from E066 kJ/mol to E141 kJ/mol at coverages 0 and 1, respectively.

Signs of attentional dysfunction mimicking spatial neglect have been described both in humans with lateralised Parkinson's Disease (PD) and in animals with MPTP-related hemiparkinsonism. Such deficits have been attributed to dopamine loss in basal ganglia and cortical targets. However, in previous studies the existence of neglect was assumed from behavioural tests which needed a motor output, thus entailing interpretation ambiguities due to effects of directional hypokinesia. We recorded brain event-related potentials (ERPs) evoked by the presentation of target somatic stimuli to the affected and non-affected sides in 44 patients with unilateral or asymmetrical PD. The N2 and P3 ERP components were specifically analysed, since (a) they are triggered selectively by task-relevant, attended sensory stimuli; (b) their latency reflects stimulus evaluation time, independently from the execution of a motor response, and (c) they have proved to be abnormal in hemineglect syndromes due to focal brain lesions. Irrespective of the side (left or right) of motor symptom predominance there were no significant ERP differences to stimulation of the affected and non-affected limbs, nor was there any correlation between ERP latencies and the degree of dopaminerelated motor impairment. The P3 latency was abnormally delayed in 23% of the patients, but there was no trend for abnormalities to concentrate on the affected side. This study does not confirm the existence of a significant attentional impairment toward the affected limb in lateralised PD, and suggests that previous clinical evidence of ‘neglect’ behaviour in PD might be linked to directional hypokinesia, thus reflecting intentional, rather than attentional lateralised deficits.