Realization and efficiency evaluation of a micro-photocatalytic cell prototype for real-time blood oxygenation

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.A novel approach to blood oxygenation is presented. Microfluidic channels molded out of PDMS (using standard soft lithography techniques) work as photocatalytic cells, where the coupling of anatase titanium dioxide (TiO2) thin films and platinum electrodes, allow an electrically assisted photocatalytic reaction to produce dissolved oxygen gas from the water content of the flowing blood. The thin films were deposited onto quartz glass substrates at room temperature (300K) using reactive RF sputtering with a Ti metal target. The results of the current study, as a proof of concept, have shown that the device can generate oxygen at a rate of 4.06×10-3 mM O2/(cm2 min) and oxygenate venous blood to the oxygen saturation level of arterial blood

Uncertainty inequalities on groups and homogeneous spaces via isoperimetric inequalities

We prove a family of $L^p$ uncertainty inequalities on fairly general groups and homogeneous spaces, both in the smooth and in the discrete setting. The crucial point is the proof of the $L^1$ endpoint, which is derived from a general weak isoperimetric inequality.Comment: 17 page

Coupled distinct element method computational fluid dynamics analyses for reservoir landslide modelling

The Vajont landslide involved a large mass of rock splashing at high speed into the reservoir which in turn generated a highimpulse water that overtopped the dam and swept away the downstream village. In several cases of reservoir landslide, albeit the flood defence structures may remain intact, a catastrophe still occur due to the generation of a ‚tsunami‘ wave. Since the features of the tsunami wave strongly depend on the physics of the rock splashing and the subsequent rock –water interaction, a numerical tool accounting for such physics is required for predictions to be reliable. Here, the formulation of a coupled 3D Distinct Element Method (DEM) – Computational Fluid Dynamics (CFD) code used to simulate the rock slide from onset to impact with the reservoir and the subsequent generation of the impulse wave, is presented. To run realistic simulations in an affordable runtime, coarse graining is employed. The main results of quasi 3D analyses in plane strain along two cross-sections representative of the eastern and western slope sectors are presented. The results show to be in broad agreement with the available recorded observations

Perylene dye photodegradation due to ketones and singlet oxygen

The photodegradation rate of a perylene dye (Lumogen F Yellow 083) in methyl isobutyrate was found to increase with ketone concentration for two different ketones. Of the ketones employed, methyl pyruvate, an impurity in methyl methacrylate, was found to be particularly deleterious to dye stability. In agreement with other published studies, the addition of the anti-oxidant DABCO (1,4-diazabicyclo-[2.2.2] octane) to the dye matrix was found to increase dye stability; however when ketones were present, DABCO lead to increased photodegradation. These results highlight the importance of removing ketone impurities from dye matrices during production of Luminescent Solar Concentrators (LSCs). © 2009 Elsevier Ltd. All rights reserved

The Evershed Effect with SOT/Hinode

The Solar Optical Telescope onboard Hinode revealed the fine-scale structure of the Evershed flow and its relation to the filamentary structures of the sunspot penumbra. The Evershed flow is confined in narrow channels with nearly horizontal magnetic fields, embedded in a deep layer of the penumbral atmosphere. It is a dynamic phenomenon with flow velocity close to the photospheric sound speed. Individual flow channels are associated with tiny upflows of hot gas (sources) at the inner end and downflows (sinks) at the outer end. SOT/Hinode also discovered ``twisting'' motions of penumbral filaments, which may be attributed to the convective nature of the Evershed flow. The Evershed effect may be understood as a natural consequence of thermal convection under a strong, inclined magnetic field. Current penumbral models are discussed in the lights of these new Hinode observations.Comment: To appear in "Magnetic Coupling between the Interior and the Atmosphere of the Sun", eds. S.S. Hasan and R.J. Rutten, Astrophysics and Space Science Proceedings, Springer-Verlag, Heidelberg, Berlin, 200

A common periodic representation of interaural time differences in mammalian cortex

Binaural hearing, the ability to detect small differences in the timing and level of sounds at the two ears, underpins the ability to localize sound sources along the horizontal plane, and is important for decoding complex spatial listening environments into separate objects - a critical factor in 'cocktail-party listening'. For human listeners, the most important spatial cue is the interaural time difference (ITD). Despite many decades of neurophysiological investigations of ITD sensitivity in small mammals, and computational models aimed at accounting for human perception, a lack of concordance between these studies has hampered our understanding of how the human brain represents and processes ITDs. Further, neural coding of spatial cues might depend on factors such as head-size or hearing range, which differ considerably between humans and commonly used experimental animals. Here, using magnetoencephalography (MEG) in human listeners, and electro-corticography (ECoG) recordings in guinea pig-a small mammal representative of a range of animals in which ITD coding has been assessed at the level of single-neuron recordings-we tested whether processing of ITDs in human auditory cortex accords with a frequency-dependent periodic code of ITD reported in small mammals, or whether alternative or additional processing stages implemented in psychoacoustic models of human binaural hearing must be assumed. Our data were well accounted for by a model consisting of periodically tuned ITD-detectors, and were highly consistent across the two species. The results suggest that the representation of ITD in human auditory cortex is similar to that found in other mammalian species, a representation in which neural responses to ITD are determined by phase differences relative to sound frequency rather than, for instance, the range of ITDs permitted by head size or the absolute magnitude or direction of ITD

Influence of Inter-Particle Friction and Damping on the Dynamics of Spherical Projectile Impacting Onto a Soil Bed

This study investigates the dynamics of a spherical projectile impact onto a granular bed via numerical simulations by discrete element method (DEM). The granular bed is modeled as an assembly of polydisperse spherical particles and the projectile is represented by a rigid sphere. The DEM model is used to investigate the cratering process, including the dynamics of the projectile and energy transformation and dissipation. The cratering process is illustrated by tracking the motion of the projectile and granular particles in the bed. The numerical results show that the dynamics of the projectile follows the generalized Poncelet law that the final penetration depth is a power-law function of the falling height. The numerical results can match well the experimental data reported in the literature, demonstrating the reliability of the DEM model in analyzing the impact of a spherical projectile on a granular bed. Further analyses illustrate that the impact process consists of three main stages, namely the impact, penetration and collapse, as characterized by the evolution of projective velocity, strong force chains and crater shape. The initial kinetic and potential energy of the projectile is dissipated mainly by inter-particle friction which governs the projectile dynamics. The stopping time of projectile decreases as the initial impact velocity increases. The final penetration depth scales as one-third the power of total falling height and is inversely proportional to the macroscopic granular friction coefficient.National Natural Science Foundation of China (No. 42107155), the Royal Society, Sino-British Fellowship Trust International Exchanges Award (No. IES\R2\202023), the Fundamental Research Funds for the Central Universities (No. 2682021CX061), the National Key R&D Program of China (No. 2017YFC1502500