In situ observation of synthesized nanoparticles in ultra-dilute aerosols via X-ray scattering

In-air epitaxy of nanostructures (Aerotaxy) has recently emerged as a viable route for fast, large-scale production. In this study, we use small-angle X-ray scattering to perform direct in-flight characterizations of the first step of this process, i.e., the engineered formation of Au and Pt aerosol nanoparticles by spark generation in a flow of N₂ gas. This represents a particular challenge for characterization because the particle density can be extremely low in controlled production. The particles produced are examined during production at operational pressures close to atmospheric conditions and exhibit a lognormal size distribution ranging from 5–100 nm. The Au and Pt particle production and detection are compared. We observe and characterize the nanoparticles at different stages of synthesis and extract the corresponding dominant physical properties, including the average particle diameter and sphericity, as influenced by particle sintering and the presence of aggregates. We observe highly sorted and sintered spherical Au nanoparticles at ultra-dilute concentrations (< 5 × 10⁵ particles/cm³) corresponding to a volume fraction below 3 × 10^–10, which is orders of magnitude below that of previously measured aerosols. We independently confirm an average particle radius of 25 nm via Guinier and Kratky plot analysis. Our study indicates that with high-intensity synchrotron beams and careful consideration of background removal, size and shape information can be obtained for extremely low particle concentrations with industrially relevant narrow size distributions.

     

Absence makes the adaptations grow fonder: Proportion of time apart from partner, male sexual psychology, and sperm competition in humans (Homo sapiens).

Sperm competition occurs when the sperm of multiple males concurrently occupy the reproductive tract of a female and compete to fertilize an egg. We used a questionnaire to investigate psychological responses to the risk of sperm competition for 237 men in committed, sexual relationships. As predicted, a man who spends a greater (relative to a man who spends a lesser) proportion of time apart from his partner since the couple's last copulation reported (a) greater sexual interest in his partner, (b) greater distress in response to his partner's sexual rejection, and (c) greater sexual persistence in response to his partner's sexual rejection. All effects were independent of total time since the couple's last copulation and the man's relationship satisfaction. Discussion addresses limitations of the current research and situates the current results within the broader comparative literature on adaptation to sperm competition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perthes' disease treated by prolonged recumbency and femoral head containment: a long-term appraisal

The results of a long-term review of 102 hips in eighty-seven patients with Perthes' disease are described, the mean follow-up interval being seventeen years. All had been treated by an extremely rigorous conservative regime in which the patients were kept in hospital for an average period of twenty-six months, during which time they were confined to bed with the legs in wide abduction, first in traction and later in "broomstick" plasters to ensure "containment" of the femoral head. The patients were assessed by the joint clincial and radiological method described by Ratliff (1956). The results were very satisfactory, with only 2 per cent poor results and 10 per cent fair. The remaining 88 per cent were good. The radiological results at the end of treatment have also been compared with control series described by Catterall (1972) and with the osteotomy series of Lloyd-Roberts, Catterall and Salamon (1976). From this it appears that the described regime offers no benefit compared with the natural history in Catterall's Groups I and II, and in Group III the results were only marginally better than those following osteotomy. In Group IV cases, however, where the femoral head was totally involved, the benefit was important, and since these are the cases which carry the worst natural prognosis it is suggested that the use of the method described in such instances must be seriously considered in spite of its social disadvantages. The theoretical implications of the findings are considered, and it is concluded that the benefits of the method cannot be ascribed wholly to the application of the "containment" principle.     

The composition of beef heart cardiolipins isolated by solvent and chromatographic fractionation

A method is described for the isolation of cardiolipin from beef heart lipids by a single pass through a silica gel column. The isolated cardiolipin was free of neutral lipids and phospholipids and accounted for 10% of total phospholipid phosphorus. It was compared to commercial cardiolipins prepared by the Pang-born method of selective precipitation. Analysis for fatty acids, glycerol and phosphorus revealed a molar ratio of 2∶1.5∶1 for both preparations, provided the fatty acid esters were assayed colorimetrically. If the fatty acids were determined by titration, the commercial cardiolipin had a molar ratio of fatty acid to phosphorus of 1.6, while ours remained at 2.0. Upon hydrolysis with acetic acid, the former yielded 76% water-soluble phosphorus, the latter only 2%. Both cardiolipins contained over 90% C-18 fatty acids, with our preparation containing 76% linoleate, the commercial preparation, 90%. After alkaline hydrolyses a component was isolated from the commercial cardiolipin which represented 15.5% of the total weight. It developed an interfering pigment in the fatty acid ester determination but has not been identified. After its removal analysis demonstrated three fatty acids per molecule of the commercial cardiolipin.     

Fractures of the distal femur in the elderly treated with a carbon fibre supracondylar plate

The use of a contoured supracondylar carbon fibre plate in 22 patients with a fracture of the lower femur is reported. The patients were all elderly (mean age 80.6 years) and three patients in the study died of unrelated medical causes. Of the 19 surviving patients, in 17 the fracture united (89 per cent). The supracondylar plate was technically simple to use and the authors feel that it represents a significant advantage over existing implants for this difficult fracture.     

Recurrent neural robot controllers: feedback mechanisms for identifying environmental motion dynamics

In this paper a series of recurrent controllers for mobile robots have been developed. The system combines the iterative learning capability of neural controllers and the optimisation ability of particle swarms. In particular, three controllers have been developed: an Exo-sensing, an Ego-sensing and a Composite controller which is the hybrid of the latter two. The task for each controller is to learn to follow a moving target and identify its trajectory using only local information. We show how the learned behaviours of each architecture rely on different sensory representations, although good results are obtained in all cases.     

An unusual case of mitral valve aneurysm: two dimensional echocardiographic and cineangiocardiographic features

A patient is described in whom an aneurysm of the posterior mitral leaflet caused severe mitral incompetence and cardiac failure. The aneurysm was seen as an additional echo-free space within the left atrium in the real time two dimensional echocardiogram. Both echocardiographic and cineangiocardiographic appearances were misinterpreted initially because the aneurysmal leaflet did not more into the left ventricle during diastole. This feature was explained during the successful surgical repair of the valve by the observation that the aneurysm was adherent to the left atrial wall.     

Perceived risk of female infidelity moderates the relationship between objective risk of female infidelity and sexual coercion in humans (Homo sapiens).

Female extrapair copulation (EPC) can be costly to a woman's long-term romantic partner. If a woman has copulated recently with a man other than her long-term partner, her reproductive tract may contain the sperm of both men, initiating sperm competition (whereby sperm from multiple males compete to fertilize an egg). Should the woman become pregnant, her long-term partner is at risk of cuckoldry—investing unwittingly in offspring to whom he is not genetically related. Previous research in humans (Homo sapiens) and in nonhuman animals suggests that males have evolved tactics such as partner-directed sexual coercion that reduce the risk of cuckoldry. The current research provides preliminary evidence that mated men (n = 223) at greater risk of partner EPC, measured as having spent a greater proportion of time apart from their partner since the couple's last in-pair copulation, more frequently perform partner-directed sexually coercive behaviors. This relationship is moderated, however, by men's perceived risk of partner EPC, such that the correlation between the proportion of time spent apart since last in-pair copulation and sexually coercive behaviors remains significant only for those men who perceive themselves to be at some risk of partner EPC. Discussion addresses limitations of this research and highlights directions for future research investigating the relationship between female EPC and men's partner-directed sexual coercion. (PsycINFO Database Record (c) 2011 APA, all rights reserved)