Determining the composition of the vacuum-liquid interface in ionic-liquid mixtures.

The vacuum-liquid interfaces of a number of ionic-liquid mixtures have been investigated using the combination of reactive-atom scattering with laser-induced fluorescence detection (RAS-LIF), selected surface tension measurements, and molecular dynamics (MD) simulations. The mixtures are based on the widespread 1-alkyl-3-methylimidazolium ([Cnmim]+) cation, including mixed cations which differ in chain length or chemical functionality with a common anion; and different anions for a common cation. RAS-LIF results imply that the surface compositions exhibit a general form of non-stoichiometric behaviour that mimics the well-known Henry's and Raoult's laws at low and high mole fraction, respectively. The extended Langmuir model provides a moderately good single-parameter fit, but higher-order terms are required for an accurate description. The quantitative relationship between RAS-LIF and surface tension, which probes the surface composition only indirectly, is explored for mixtures of [C2mim]+ and [C12mim]+ with a common bis(trifluoromethylsulfonyl)imide ([NTf2]-) anion. Extended Langmuir model fits to surface tension data are broadly consistent with those to RAS-LIF; however, several other common approaches to extracting surface compositions from measured surface tensions result in much larger discrepancies. MD simulations suggest that RAS-LIF faithfully reports on the alkyl-chain exposure at the surface, which is only subtly modified by composition-dependent structural reorganisation.

Bent-core liquid crystals forming two- and three-dimensional modulated structures.

Two columnar phases of bent-core molecules have been observed, with a two-dimensional (2D) structure modulated in the plane perpendicular to the direction of the spontaneous polarization vector. The phases are switchable under an applied electric field, contrary to the commonly observed 2D modulated B1 phase. These new phases are built from broken smectic layers with orthogonal or tilted molecules. The evidence for a 3D structure in which the density modulations along and perpendicular to the spontaneous polarization vector co-exists is also given.

Specific molecular interactions in Pd(II) complexes identify a new approach to the biaxial nematic phase.

Liquid-crystalline complexes of Pd(II) allow a new approach to the realisation of the biaxial nematic phase.

Visual field loss after stroke: confrontation and perimetry in the assessment of recovery.

The purpose of this study was to examine the recovery of visual field deficits after first-ever stroke and to determine the accuracy of standard clinical assessment using oculokinetic perimetry. Of 148 patients with a hemisphere stroke and a normal conscious level, 75 (50.6%) were found to have a visual field deficit by clinical examination. Only 19 (11 women) stroke patients with visual field deficits were able to complete a perimetric examination within 1 week of their stroke. They were followed-up for a period of 12 weeks with serial clinical and perimetric examinations every 4 weeks. Clinical assessment of the patient failed to note further recovery after 4 weeks. By using oculokinetic perimetry, 8 (42.1%) patients recovered central vision but had a persistent peripheral field loss; maximal recovery of central vision was noted in the first 4 weeks. By using oculokinetic perimetry as the gold standard, the sensitivity of clinical assessment of visual field deficits was 94.4% on admission. The sensitivity fell to 55.5% during follow-up because of the clinicians' inability to detect central recovery by confrontation. The small numbers recruited show the difficult in recruiting acute stroke patients in measurements of recovery.

Calamitics, cubics, and columnars-liquid-crystalline complexes of silver(I).

The study of metallomesogens has added several new dimensions to the wider field of liquid crystals. In this Account, just one family of complexes is considered, namely alkoxystilbazole complexes of various silver(I) salts. These complexes show an incredibly rich and diverse mesomorphism ranging from nematic and smectic to columnar phases; in particular, many complexes show the still rare thermotropic cubic phase. Through systematic structural variations, it has been possible to gain a good understanding of the factors influencing the behavior of these fascinating systems.

The association of visual field deficits and visuo-spatial neglect in acute right-hemisphere stroke patients.

BACKGROUND: Visuo-spatial neglect (VSN) after stroke is associated with a poor prognosis for rehabilitation. The co-existence of a visual field deficit (VFD) with VSN may be associated with impaired visuo-spatial functioning and thereby poor functional outcome. OBJECTIVE: To determine whether the presence of a VFD (i) exacerbates VSN and (ii) influences recovery of VSN. METHODS: A prospective study of consecutive acute (<7 days), right-hemisphere stroke patients who were able to undergo detailed assessment of visuo-spatial functioning and visual fields. Clinical assessment and a standardized neuropsychological test was administered by one observer, followed by independent assessment of visual fields by a second observer. Patients were followed up for 12 weeks with 4-weekly re-assessments. RESULTS: 44 consecutive patients (23 women) with a first in a lifetime, acute hemisphere stroke were recruited. Twenty had VSN and VFD, seven VSN only, one VFD only and 17 had normal visual fields and no neglect. The finding of a VFD was significantly associated with the presence of VSN (P<0.0001). Patients with both VFD and VSN had a significantly lower score on the behavioural inattention test. One month post-stroke, this difference was no longer significant. Recovery of VSN and VFD was maximal in the first month, however VSN recovery continued for up to 12 weeks. Patients with VSN and a VFD on admission had a greater mortality at 1 and 3 months. CONCLUSION: The presence of a VFD does appear to exacerbate neglect in the acute stroke patient; this effect is no longer seen after 1 month. Recovery of VSN continues independent of a VFD. Patients with neglect and a VFD have an increased mortality, probably because of greater neurological impairment.

Economic effects of clinical chicken anemia agent infection on profitable broiler production.

An outbreak of anemia dermatitis syndrome caused by chicken anemia agent (CAA) occurred in 15 broiler flocks. An average of 29% of chickens in these flocks were derived from a common breeder flock. The breeder flock had no antibody to CAA at 20 weeks of age but had seroconverted by 31 weeks. Diseased broiler flocks were derived from eggs laid by the breeder flock between 25 and 30 weeks of age. CAA infection in the breeder flock was subclinical, with no apparent effects on mortality or performance. A strategic program of therapeutic and/or prophylactic antibiotic therapy was begun in affected broiler flocks as soon as the disease was diagnosed. Nevertheless, when the cost of therapy was taken into account, affected broiler flocks had a net income 17.3% to 19.6% lower than normal flocks. Average bird weights were 3.3% to 3.5% lower in affected flocks than in unaffected flocks, and affected flocks had a significantly greater proportion of lighter birds. Average mortality in affected flocks was 2.0% to 2.3% higher than in normal flocks, with peak mortality occurring in the third week of life. There was no apparent effect on feed-conversion ratio.

The cost benefit of vaccinating broiler flocks against subclinical infectious bursal disease.

In an attempt to reduce economic losses due to subclinical infectious bursal disease (IBD), broilers reared in 23 houses known to have been infected with IBD virus were vaccinated with live, attenuated IBD virus vaccine at 20 days of age. Vaccination of either one, two or three consecutive flocks resulted in significant increases in net income and average bird weight, and in a decrease in mortality. An improvement in broiler performance was not restricted to vaccinated flocks, but was also apparent for at least 1 year following placing of the first vaccinated flock in subsequent flocks reared in the same houses.

Economic effects of subclinical chicken anemia agent infection in broiler chickens.

To evaluate the economic effects of subclinical chicken anemia agent (CAA) infection on broiler performance, clinically normal broiler flocks were grouped into two categories: A) flocks in which none of 10 birds sampled at slaughter had antibody to CAA, and B) flocks in which six or more of 10 similarly sampled birds had CAA antibody. Production and performance parameters of 25 flocks in each category were compared. No statistically significant differences were found between category A and category B flocks in major production parameters such as sex, feed manufacturer, type of litter, stocking density, and age at slaughter. However, category A flocks achieved 13% (P less than 0.05) greater net income per 1000 birds, 2.0% better feed-conversion ratio (P less than 0.05), and 2.5% (P less than 0.05) greater average weight per bird than category B flocks. No significant differences in hockburn bonus per 1000 birds (a bonus payable to growers whose broilers have the lowest prevalence of contact dermatitis lesions on the hocks) and mortality were found between category A and category B flocks. These results show that subclinical CAA infection has a substantial, statistically significant effect on commercial broiler performance and profitability.

Epidemiology of a contact dermatitis of broilers.

A computerised information retrieval system of broiler production data has been used to study the epidemiology of contact dermatitis. The results of the analyses of broiler production data for the period 1984/85 were compared and contrasted with those for the period 1986/1987. The prevalence of breast lesions recorded in the latter period was 33% less than in the former. The prevalence of hock lesions was similar in both periods, but the degree of variation in the prevalence of lesions recorded by individual flocks was substantially reduced in 1986/87. Stocking density, average age of removal and the sex of birds all had an effect on the prevalence of the condition in broiler flocks in both time periods. The condition was more frequently recorded in flocks during the winter and a strong correlation with ambient relative humidity, obtained.