Studying model suspensions using high resolution synchrotron X-ray microtomography

The addition of minor quantities of secondary liquids to suspensions may lead to a transition from a fluid-like structure to paste-like structure for the system. Previous studies have shown how rheological properties such as viscosity and yield stress are affected, however, qualitative visual observation on the micro-scale during both short and long term storage has yet to be achieved or reported. This research focuses on the movement of a secondary immiscible liquid (water or saturated sucrose solution) when added to a model food system. The model food system used in this study is a suspension of sucrose particles in a continuous oil phase to better understand the interactions between the particles and the liquid phases present. This was accomplished using dynamic X-ray computer tomography to study the behaviour of the sample. This non-destructive approach allowed the movement of the secondary liquid as well as the solid particles from the bulk suspension to be monitored through a time lapse of scans. This was achieved by observing the changes in the grey scale range of the droplet with time, which was then correlated to the uptake and movement of sucrose into the secondary liquid using an innovative method. This movement was due to the hydrophilicity and solubility of sucrose with gravity/sedimentation playing a minimal role

Direct digital control of an efficient silicon+lequid crystal phase shifter

We demonstrate a phase shifter based on a silicon slot waveguide infiltrated with liquid crystal. We achieve a phase shift of 73 pi for a 5V drive voltage, with a voltage-length product of 0.022V.mm around 1V. We can drive the phase shifter directly with a 1V, duobinary pulse-width-modulated signal, allowing direct digital CMOS control of an analog optical phase shifter

Silicon-organic hybrid electro-optical devices

Organic materials combined with strongly guiding silicon waveguides open the route to highly efficient electro-optical devices. Modulators based on the so-called silicon-organic hybrid (SOH) platform have only recently shown frequency responses up to 100 GHz, high-speed operation beyond 112 Gbit/s with fJ/bit power consumption. In this paper, we review the SOH platform and discuss important devices such as Mach-Zehnder and IQ-modulators based on the linear electro-optic effect. We further show liquid-crystal phase-shifters with a voltage-length product as low as V pi L = 0.06 V.mm and sub-mu W power consumption as required for slow optical switching or tuning optical filters and devices

40 Gbit/s silicon-organic hybrid (SOH) phase modulator

A 40 Gbit/s electro-optic modulator is demonstrated. The modulator is based on a slotted silicon waveguide filled with an organic material. The silicon organic hybrid (SOH) approach allows combining highly nonlinear electro-optic organic materials with CMOS-compatible silicon photonics technology

Plasma testosterone in fetal rats and their mothers on day 19 of gestation

Plasma testosterone levels were higher in pooled samples from male fetuses than from female fetuses on day 19 of pregnancy. Plasma testosterone from female fetuses with males located caudally in the uterus was higher than from females that lacked such males. Testosterone level of both male and female fetuses was correlated with maternal testosterone. No correlation was found between maternal testosterone and number of males in the litter, male-to-female ratio, or litter size. These results corroborate earlier findings of a sex difference in plasma testosterone levels on fetal day 19 in rats, and provide support for the hypothesis that female rats receive androgens from males located caudally in the uterus. No evidence was found that testosterone of pregnant females is affected by the sex ratio or size of her litter

Silicon-Organic Hybrid (SOH) and Plasmonic-Organic Hybrid (POH) integration

Silicon photonics offers tremendous potential for inexpensive high-yield photonic-electronic integration. Besides conventional dielectric waveguides, plasmonic structures can also be efficiently realized on the silicon photonic platform, reducing device footprint by more than an order of magnitude. However, nei-ther silicon nor metals exhibit appreciable second-order optical nonlinearities, thereby making efficient electro-optic modulators challenging to realize. These deficiencies can be overcome by the concepts of silicon-organic hybrid (SOH) and plasmonic-organic hybrid integration, which combine SOI waveguides and plasmonic nanostructures with organic electro-optic cladding materials

Dopamine-modulated dynamic cell assemblies generated by the GABAergic striatal microcircuit

The striatum, the principal input structure of the basal ganglia, is crucial to both motor control and learning. It receives convergent input from all over the neocortex, hippocampal formation, amygdala and thalamus, and is the primary recipient of dopamine in the brain. Within the striatum is a GABAergic microcircuit that acts upon these inputs, formed by the dominant medium-spiny projection neurons (MSNs) and fast-spiking interneurons (FSIs). There has been little progress in understanding the computations it performs, hampered by the non-laminar structure that prevents identification of a repeating canonical microcircuit. We here begin the identification of potential dynamically-defined computational elements within the striatum. We construct a new three-dimensional model of the striatal microcircuit's connectivity, and instantiate this with our dopamine-modulated neuron models of the MSNs and FSIs. A new model of gap junctions between the FSIs is introduced and tuned to experimental data. We introduce a novel multiple spike-train analysis method, and apply this to the outputs of the model to find groups of synchronised neurons at multiple time-scales. We find that, with realistic in vivo background input, small assemblies of synchronised MSNs spontaneously appear, consistent with experimental observations, and that the number of assemblies and the time-scale of synchronisation is strongly dependent on the simulated concentration of dopamine. We also show that feed-forward inhibition from the FSIs counter-intuitively increases the firing rate of the MSNs. Such small cell assemblies forming spontaneously only in the absence of dopamine may contribute to motor control problems seen in humans and animals following a loss of dopamine cells. (C) 2009 Elsevier Ltd. All rights reserved

WS22D nanosheets in 3D nanoflowers

In this work it has been established that 3D nanoflowers of WS2 synthesized by chemical vapour deposition are composed of few layer WS2 along the edges of the petals. An experimental study to understand the evolution of these nanostructures shows the nucleation and growth along with the compositional changes they undergo