X-ray absorption study of Ti-activated sodium aluminum hydride

Ti K-edge x-ray absorption near edge spectroscopy (XANES) was used to explore the Ti valence and coordination in Ti-activated sodium alanate. An empirical relationship was established between the Ti valence and the Ti K-edge onset based on a set of standards. This relationship was used to estimate oxidation states of the titanium catalyst in 2 mol% and 4 mol% Ti-doped NaAlH4. These results demonstrate that the formal titanium valence is zero in doped sodium alanate and nearly invariant during hydrogen cycling. A qualitative comparison of the edge fine structure suggests that the Ti is present on the surface in the form of amorphous TiAl3.Comment: 3 pages, 4 figures, submitted to Appl. Phys. Let

Limited risks of major congenital anomalies in children of mothers with coeliac disease: a population-based cohort study

Objective: To examine major congenital anomaly (CA) risks in children of mothers with coeliac disease (CD) compared with mothers without CD. Design: Population-based cohort study. Setting: Linked maternal–child medical records from a large primary care database from the UK. Population: A total of 562 332 live singletons of mothers with and without CD in 1990–2013. Methods: We calculated the absolute major CA risks in children whose mothers had CD, and whether this was diagnosed or undiagnosed before childbirth. Logistic regression with a generalised estimating equation was used to estimate adjusted odds ratios (aORs) with 95% confidence intervals (95% CIs) for CAs associated with CD. Main outcome measures: Fourteen system-specific major CA groups classified according to the European Surveillance of Congenital Anomalies and neural tube defects (NTDs). Results: Major CA risk in 1880 children of mothers with CD was 293 per 10 000 liveborn singletons, similar to the risk in those without CD (282; aOR 0.98, 95% CI 0.74–1.30). The risk was slightly higher in 971 children, whose mothers were undiagnosed (350; aOR 1.14, 95% CI 0.79–1.64), than in 909 children whose mothers were diagnosed (231; aOR 0.80, 95% CI 0.52–1.24). There was a three-fold increase in nervous system anomalies in the children of mothers with undiagnosed CD (aOR 2.98, 95% CI 1.06–8.33, based on five exposed cases and one had an NTD), and these women were all diagnosed with CD at least 4 years after their children were born. Conclusions: There was no statistically significant increase in risk of major CAs in children of mothers with coeliac disease overall, compared with the general population

"The legacy of thalidomide" - A multidisciplinary meeting held at the University of York, United Kingdom, on September 30, 2016 : A multidisciplinary meeting held at the University of York, UK on September 30, 2016

BACKGROUND: Between 1957 and 1962 thalidomide was used as a nonaddictive, nonbarbiturate sedative that also was successful in relieving the symptoms of morning sickness in early pregnancy. Infamously, thousands of babies were subsequently born with severe birth defects. The drug is used again, today, to successfully treat leprosy, and tragically, there is a new generation of thalidomide damaged children in Brazil. While the outward damage in babies has been documented, the effects of the damage upon the survivors as they grow up, the lifestyle changes and adaptations required to be made, as well as studies into ageing in survivors, has received little attention and remains understudied. METHODS: A unique multidisciplinary meeting was organized at the University of York bringing together thalidomide survivors, clinicians, scientists, historians, and social scientists to discuss the past, the current and the future implications of thalidomide. RESULTS: There is still much to learn from thalidomide, from its complex history and ongoing impact on peoples' lives today, to understanding its mechanism/s to aid future drug safety, to help identify new drugs retaining clinical benefit without the risk of causing embryopathy. CONCLUSION: For thalidomide survivors, the original impairments caused by the drug are compounded by the consequences of a lifetime of living with a rare disability, and early onset age-related health problems. This has profound implications for their quality of life and need for health and social care services. It is vital that these issues are addressed in research, and in clinical practice if thalidomide survivors are to "age well". Birth Defects Research 109:296-299, 2017. © 2017 Wiley Periodicals, Inc

Molecular Dynamics Simulation of Mechanical Deformation of Ultra-Thin Metal and Ceramic Films

We present an overview of the molecular dynamics computer simulation method as employed in the study of the mechanical properties of surfaces at the manometer scale. The embedded atom method is used to model a clean metal surface and the bond-order model is used to model ceramic surfaces. The computer experiment consists of the indentation and scraping of a hard diamond-like tool into and across the surface. Results are presented for the (111) surface of copper and silver and for the (100) surface of silicon. We explicitly demonstrate in our point indentation simulations that nanoscale plasticity in metals takes place by nondislocation mechanisms, a result suggested by recent nanoindentation experiments. We also observe the surface to accommodate nearly the entire volume of the tip and the annealing out of plastic work as the tip is removed. In our orthogonal cutting simulation, we observe an interesting phenomenon: the system dynamically reorients the gain in front of the tool tip to minimize the work performed on the shear plane (i.e. the shear plane becomes an easy slip plane). Silicon transforms into an amorphous state which then flows plastically

Time-efficient sintering processes to attach power devices using nanosilver dry film

Pressure-assisted sintering processes to attach power devices using wet nanosilver pastes with time scales of minutes to a few hours have been widely reported. This paper presents our work on time-efficient sintering, using nanosilver dry film and an automatic die pick and place machine, resulting in process times of just a few seconds. The combined parameters of sintering temperature 250 °C, sintering pressure 10 MPa and sintering time 5 s were selected as the benchmark process to attach 2 mm × 2 mm × 0.5 mm dummy Si devices. Then the effects of either the sintering temperature (240 to 300 °C), time (1 to 9 s) or pressure (6 to 25 MPa) on the porosity and shear strength of the sintered joints were investigated with 3 groups and a total of 13 experimental trials. The average porosities of 24.6 to 46.2% and shear strengths of 26.1 to 47.7 MPa are comparable with and/or even better than those reported for sintered joints using wet nanosilver pastes. Their dependences on the sintering temperature, time and pressure are further fitted to equations similar to those describing the kinetics of sintering processes of powder compacts. The equations obtained can be used to not only reveal different mechanisms dominating the densification and bonding strength, but also anticipate the thermal-induced evolutions of microstructures of these rapidly sintered joints during future reliability tests and/or in service

CPS49-induced neurotoxicity does not cause limb patterning anomalies in developing chicken embryos

The authors thank Elizabeth Kilby and Susan Reijntes for preliminary studies. CM was funded by a University of Aberdeen PhD studentship; AJR (née Diamond) was funded through a BBSRC EastBio DTP PhD Award; S-L B was funded by a Wellcome Trust/NIH PhD Studentship; SM was funded by a Siddall PhD Scholarship Award; LRF was funded by the Science Without Borders PhD Scheme.Peer reviewedPostprin

Ab initio study of ternary W5Si3 type TM5Sn2X compounds (TM = Nb, Ti and X = Al, Si)

The adhesion of the scale formed on Nb-silicide based alloys at 1473 K improves when Al and Sn are in synergy with Si and Ti. This improvement is observed when there is segregation of Sn in the microstructure below the alloy/scale interface and a layer rich in intermetallics that include TM5Sn2X compounds is formed at the interface. Data for the ternary compounds is scarce. In this paper elastic and thermodynamic properties of the Nb5Sn2Al, Ti5Sn2Si, Ti5Sn2Al and Nb5Sn2Si compounds were studied using the first-principles, pseudopotential plane-wave method based on density functional theory. The enthalpy of formation of the ternary intermetallics was calculated using the quasi-harmonic approximation. The calculations suggest that the Nb5Sn2Si is the stiffest; that the Nb5Sn2Al and Ti5Sn2Si are the most and less ductile phases respectively; and that Nb significantly increases the bulk, shear and elastic moduli of the ternary compound compared with Ti

Genetics of human neural tube defects

Neural tube defects (NTDs) are common, severe congenital malformations whose causation involves multiple genes and environmental factors. Although more than 200 genes are known to cause NTDs in mice, there has been rather limited progress in delineating the molecular basis underlying most human NTDs. Numerous genetic studies have been carried out to investigate candidate genes in cohorts of patients, with particular reference to those that participate in folate one-carbon metabolism. Although the homocysteine remethylation gene MTHFR has emerged as a risk factor in some human populations, few other consistent findings have resulted from this approach. Similarly, attention focused on the human homologues of mouse NTD genes has contributed only limited positive findings to date, although an emerging association between genes of the non-canonical Wnt (planar cell polarity) pathway and NTDs provides candidates for future studies. Priorities for the next phase of this research include: (i) larger studies that are sufficiently powered to detect significant associations with relatively minor risk factors; (ii) analysis of multiple candidate genes in groups of well-genotyped individuals to detect possible gene–gene interactions; (iii) use of high throughput genomic technology to evaluate the role of copy number variants and to detect ‘private’ and regulatory mutations, neither of which have been studied to date; (iv) detailed analysis of patient samples stratified by phenotype to enable, for example, hypothesis-driven testing of candidates genes in groups of NTDs with specific defects of folate metabolism, or in groups of fetuses with well-defined phenotypes such as craniorachischisis