Thermal stability of titanium nitride for shallow junction solar cell contacts

To demonstrate the thermal stability of titanium nitride as a high-temperature diffusion barrier, the TiN-Ti-Ag metallization scheme has been tested on shallow-junction (~2000 Å) Si solar cells. Electrical measurements on reference samples with the Ti-Ag metallization scheme show serious degradation after a 600 °C, 10-min annealing. With the TiN-Ti-Ag scheme, no degradation of cell performance is observed after the same heat treatment if the TiN layer is >~1700 Å. The glass encapsulation of cells by electrostatic bonding requires such a heat treatment

Generation and manipulation of magnetic droplets

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.The continuous flow generation and downstream manipulation of magnetic droplets inside a microfluidic device was investigated. Magnetic droplets were generated from aqueous ferrofluids in organic oil phase using T-junction and flow-focusing geometries in glass microfluidic devices. Due to the hydrophilic nature of glass surfaces, it was necessary to apply a hydrophobic coating in the form fluorocarbons. The size of the magnetic droplets and distance between them were controlled by adjusting the relative flow velocities of ferrofluid and oil carrier liquid. Two modes of droplet manipulation were investigated by placing small permanent magnets in the vicinity of the microfluidic channels: (i) droplet deflection across a flow chamber which could be used for sorting of droplets based on the magnetic field applied and (ii) droplet splitting at a branching junction resulting in two daughter droplets of high and low magnetite content.This study is funded by The University of Kuwait

The temporary anatomical structures prominent in the first trimester may be fulfilling exchange functions assigned to the placenta in the second and third trimester

The extra-embryonic coelom (EEC) and secondary yolk sac are prominent structures in the gestational sac during the first trimester of human pregnancy, at a time before the definitive placental circulation becomes established. We propose that the EEC and yolk sac play a critical role in the nutrition of early pregnancy, fulfilling exchange functions which are assumed by the placenta at a later stage

The generation of multi-laminar reagent streams for rapid, sequential (bio)chemical reactions on magnetic particles in a continuous flow microreactor

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.We demonstrate a versatile microfluidic system for performing rapid, consecutive (bio)chemical reactions in continuous flow. Surface-functionalised magnetic microparticles are introduced into a chamber and pulled, via a magnet, across a series of laminar flow streams containing different reagents, thus performing multiple sequential reactions on the particles’ surface. Such a continuous flow method eliminates many of the inefficiencies associated with batch techniques, such as the time-consuming, laborious sequential reaction and washing steps, to yield a system that can perform analyses far more rapidly and with less reagent volume than conventional methods. This innovative device has been applied to a two-reaction step mouse IgG sandwich immunoassay and one- and two-reaction step DNA hybridisation assays, all of which were completed within one minute. These results pave the way for a multi-purpose microreactor that can perform a variety of analytical and synthetic processes.This study is funded by the Engineering and Physical Sciences Research Council (EPSRC)

Direct evidence for the magnetic ordering of Nd ions in NdFeAsO by high resolution inelastic neutron scattering

We investigated the low energy excitations in the parent compound NdFeAsO of the Fe-pnictide superconductor in the $\mu$eV range by a back scattering neutron spectrometer. The energy scans on a powder NdFeAsO sample revealed inelastic peaks at E = 1.600 $\pm 0.003 \mu$eV at T = 0.055 K on both energy gain and energy loss sides. The inelastic peaks move gradually towards lower energy with increasing temperature and finally merge with the elastic peak at about 6 K. We interpret the inelastic peaks to be due to the transition between hyperfine-split nuclear level of the $^{143}$Nd and $^{145}$Nd isotopes with spin $I = 7/2$. The hyperfine field is produced by the ordering of the electronic magnetic moment of Nd at low temperature and thus the present investigation gives direct evidence of the ordering of the Nd magnetic sublattice of NdFeAsO at low temperature

Temperature-based tuning of magnetic particle separation by on-chip free-flow magnetophoresis

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.Free-flow magnetophoresis provides a fast and efficient means of continuous flow magnetic separation for the detection of biological analytes, due to the wide variety of magnetic particle surface properties available for binding specific targets. Here, we investigate the effect of temperature changes on the deflection behaviour of magnetic particles in a microfluidic magnetophoresis separation chamber. It was found that the extent of deflection was greatly increased at higher temperatures due to decreased solution viscosity and thus reduced resistance against particle motion. This concept was used to improve the resolution of the separation of 2.8 μm and 1 μm diameter magnetic particles. Hence, controlling the temperature of the separation system provides a simple but highly effective means of enhancing magnetic separation efficiency. This concept could also be applied to the temperature-based tuning of microparticle trajectories in many others types of continuous flow processes, such as those using optical, electrical or acoustic forces.This study is funded by the Engineering and Physical Sciences Research Council (EPSRC)

Shifting vital rate correlations alter predicted population responses to increasingly variable environments

Author Posting. © University of Chicago Press , 2019. This article is posted here by permission of University of Chicago Press for personal use, not for redistribution. The definitive version was published in Iles, D. T., Rockwell, R. F., & Koons, D. N. Shifting vital rate correlations alter predicted population responses to increasingly variable environments. American Naturalist, 193(3), (2019): E57-E64. , doi:10.1086/701043.Time series of vital rates are often used to construct “environment-blind” stochastic population projections and calculate the elasticity of population growth to increased temporal variance in vital rates. Here, we show that the utility of this widely used demographic tool is greatly limited by shifts in vital rate correlations that occur as environmental drivers become increasingly variable. The direction and magnitude of these shifts are unpredictable without environmentally explicit models. Shifting vital rate correlations had the largest fitness effects on life histories with short to medium generation times, potentially hampering comparative analyses based on elasticities to vital rate variance for a wide range of species. Shifts in vital rate correlations are likely ubiquitous in increasingly variable environments, and further research should empirically evaluate the life histories for which detailed mechanistic relationships between vital rates and environmental drivers are required for making reliable predictions versus those for which summarized demographic data are sufficient.D.T.I. received support from Ducks Unlimited Canada, the S. J. and Jesse E. Quinney Foundation, Utah State University, the Frank M. Chapman Memorial Fund, and California Waterfowl. D.N.K. is supported by a James C. Kennedy Endowed Chair of Wetland and Waterfowl Conservation. We thank the editors and anonymous reviewers whose insightful comments greatly improved our study.2020-01-0

Attachment-security priming attenuates amygdala activation to social and linguistic threat

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.A predominant expectation that social relationships with others are safe (a secure attachment style), has been linked with reduced threat-related amygdala activation. Experimental priming of mental representations of attachment security can modulate neural responding, but the effects of attachment-security priming on threat-related amygdala activation remains untested. Using functional magnetic resonance imaging, the present study examined the effects of trait and primed attachment security on amygdala reactivity to threatening stimuli in an emotional faces and a linguistic dot-probe task in 42 healthy participants. Trait attachment anxiety and attachment avoidance were positively correlated with amygdala activation to threatening faces in the control group, but not in the attachment primed group. Furthermore, participants who received attachment-security priming showed attenuated amygdala activation in both the emotional faces and dot-probe tasks. The current findings demonstrate that variation in state and trait attachment security modulates amygdala reactivity to threat. These findings support the potential use of attachment security-boosting methods as interventions and suggest a neural mechanism for the protective effect of social bonds in anxiety disorders