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We outline a strategy to improve the thermoelectric performance of n-type XNiSn based half-Heusler alloys through Cu doping into vacant tetrahedral sites. A comprehensive combination of structural characterisation and modelling is employed to discriminate the competing mechanisms for thermoelectric enhancement. During synthesis a mineralising effect occurs that improves the homogeneity of the alloying elements Ti, Zr and Hf, and promotes grain growth, leading to a doubling of the electron mobility. In the formed materials, Cu is a strong n-type dopant, like Sb, but occupies the interstitial site and strongly enhances phonon scattering without diminishing carrier mobility (in contrast to interstitial Ni). Simultaneous alloying with Ti, Zr and Hf serves to minimise the thermal conductivity via regular mass disorder and strain effects. A best electronic power factor, S2/ρ, of 3.6 mW m−1 K−2 and maximum ZT of 0.8 at 773 K were observed for a Ti0.5Zr0.25Hf0.25NiCu0.025Sn composition, enabling promising device power densities of ∼6 W cm−2 and ∼8% conversion efficiency from a 450 K gradient. These findings are important because they provide new insight into the mechanisms underpinning high ZT in the XNiSn system and indicate a direction for further improvements in thermoelectric performance. [ABSTRACT FROM AUTHOR]

Oxygen isotope ratios of quartz inclusions (QI) within garnet from granulite and amphibolite facies gneisses in the Adirondack Mountains, NY were analysed and used to determine metamorphic temperatures. Primary QI for eight of 12 samples have δ18O values significantly lower than matrix quartz (MQ). The primary QI retain δ18O values representative of thermal conditions during garnet crystallization, whereas the δ18O values of MQ were raised by diffusive exchange with other matrix minerals (e.g. mica and feldspar) during cooling. The δ18O differences between QI and MQ show that garnet (a mineral with slow diffusion of oxygen) can armour QI from isotopic exchange with surrounding matrix, even during slow cooling. These differences between δ18O in MQ and QI can further be used to test cooling rates by Fast Grain Boundary diffusion modelling. Criteria for identifying QI that preserve primary compositions and are suitable for thermometry were developed based on comparative tests. Relations between δ18O and inclusion size, distance of inclusion to host-garnet rim, core-rim zonation of individual inclusions, and presence or absence of petrological features (healed cracks in QI, inclusions in contact with garnet cracks lined by secondary minerals, and secondary minerals along the inclusion grain boundary) were investigated. In this study, 61% of QI preserve primary δ18O and 39% were associated with features that were linked to reset δ18O values. If δ18O in garnet is homogeneous and inclusions are removed, laser-fluorination δ18O values of bulk garnet are more precise, more accurate, and best for thermometry. Intragrain δ18O(Grt) profiles measured in situ by ion microprobe show no δ18O zonation. Almandine-rich garnet (Alm60-75) from each sample was measured by laser-fluorination mass-spectrometry ( LF- MS) for δ18O and compared with ion microprobe measurements of δ18O in QI for thermometry. The Δ18O(Qz-Grt) values for Adirondack samples range from 2.66 to 3.24‰, corresponding to temperatures of 640-740 °C (A[Qz-Alm] = 2.71). Out of 12 samples that were used for thermometry, nine are consistent with previous estimates of peak temperature (625-800 °C) based on petrological and carbon-isotope thermometry for regional granulite and upper amphibolite facies metamorphism. The three samples that disagree with independent thermometry for peak metamorphism are from the anorthosite-mangerite-charnockite-granite suite in the central Adirondacks and yield temperatures of 640-665 °C, ~100 °C lower than previous estimates. These low temperatures could be interpreted as thermal conditions during late (post-peak) crystallization of garnet on the retrograde path. [ABSTRACT FROM AUTHOR]

Type I recessive congenital methaemoglobinaemia (RCM), caused by the reduced form of nicotinamide adenine dinucleotide (NADH)-cytochrome b5 reductase (cyt b5r) deficiency, manifests clinically as cyanosis without neurological dysfunction. Two mutations, E255- and G291D, have been identified in the NADH-binding lobe of cyt b5r in previously reported patients, and we have detected a further novel mutation, D239G, in this lobe in two unrelated Irish families. Although one family belongs to the genetically isolated Traveller Community, which separated from the general Irish population during the 1845–48 famine, the D239G mutation was present on the same haplotype in both families. Three known cyt b5r mutations were also identified, including the R159- mutation, which causes loss of the entire NADH-binding lobe and had previously been reported in an individual with type II RCM. Characterization of the three NADH-binding lobe mutants using a heterologous expression system revealed that all three variants retained stoichiometric levels of flavin adenine dinucleotide with spectroscopic and thermodynamic properties comparable with those of native cyt b5r. In contrast to the E255- and G291D variants, the novel D239G mutation had no adverse impact on protein thermostability. The D239G mutation perturbed substrate binding, causing both decreased specificity for NADH and increased specificity for NADPH. Thus cyt b5r deficient patients who are heterozygous for an NADH-binding lobe mutation can exhibit the clinically less severe type I phenotype, even in association with heterozygous deletion of the NADH-binding lobe. [ABSTRACT FROM AUTHOR]

A prospective study of abdominal ultrasound was undertaken in 100 consecutive infants who presented with a history of persistent vomiting aged 5 to 90 days. Each infant had a 'test feed' followed by an ultrasonographic scan of the pylorus at the cotside. On test feeding a palpable tumour was evident in 38 infants. On real time ultrasound using the criteria for diagnosing pyloric stenosis, these 38 infants as well as six others were documented as having pyloric stenosis. In the other 56 patients the vomiting settled in six and a barium examination was performed on the remaining 50. This confirmed gastro-oesophageal reflux in 46, two of whom had an associated hiatus hernia, one with a duodenal malrotation, and three were reported as normal. Ultrasound of the abdomen is an accurate, reliable, and rapid screening method to differentiate the causes of severe vomiting in infancy. [ABSTRACT FROM PUBLISHER]

Reports that compressivehead-wrapping has been advocated as an alternative to surgery in the treatment of selected cases of hydrocephalus. Absence of irritability, vomiting, scalp problems or apparent neurologic deficit; Recommendation of the physician not to repeat the air-ventriculograms after the treatment; Use of other drugs in the control of the ventricular enlargement to allow more time for absorption of the blood clot.

Pyloric muscle dimensions were measured in 1400 consecutive newborn infants. Nine of these subsequently developed pyloric stenosis. Their pyloric measurements at birth were all within the normal range. Congenital preformed muscular hypertrophy does not appear to be present in babies who later develop pyloric stenosis. [ABSTRACT FROM AUTHOR]