7,452 research outputs found
A review of metal foam and metal matrix composites for heat exchangers and heat Sinks
Recent advances in manufacturing methods open the possibility for broader use of metal foams and metal matrix composites (MMCs) for heat exchangers, and these materials can have tailored material properties. Metal foams in particular combine a number of interesting properties from a heat exchanger's point of view. In this paper, the material properties of metal foams and MMCs are surveyed, and the current state of the art is reviewed for heat exchanger applications. Four different applications are considered: liquid-liquid, liquid-gas, and gas-gas heat exchangers and heat sinks. Manufacturing and implementation issues are identified and discussed, and it is concluded that these materials hold promise both for heat exchangers and heat sinks, but that some key issues still need to be solved before broad-scale application is possible
Chronic neural probe for simultaneous recording of single-unit, multi-unit, and local field potential activity from multiple brain sites
Drug resistant focal epilepsy can be treated by resecting the epileptic focus
requiring a precise focus localization using stereoelectroencephalography
(SEEG) probes. As commercial SEEG probes offer only a limited spatial
resolution, probes of higher channel count and design freedom enabling the
incorporation of macro and microelectrodes would help increasing spatial
resolution and thus open new perspectives for investigating mechanisms
underlying focal epilepsy and its treatment. This work describes a new
fabrication process for SEEG probes with materials and dimensions similar to
clinical probes enabling recording single neuron activity at high spatial
resolution. Polyimide is used as a biocompatible flexible substrate into which
platinum electrodes and leads are...
The resulting probe features match those of clinically approved devices.
Tests in saline solution confirmed the probe stability and functionality.
Probes were implanted into the brain of one monkey (Macaca mulatta), trained to
perform different motor tasks. Suitable configurations including up to 128
electrode sites allow the recording of task-related neuronal signals. Probes
with 32 and 64 electrode sites were implanted in the posterior parietal cortex.
Local field potentials and multi-unit activity were recorded as early as one
hour after implantation. Stable single-unit activity was achieved for up to 26
days after implantation of a 64-channel probe. All recorded signals showed
modulation during task execution. With the novel probes it is possible to
record stable biologically relevant data over a time span exceeding the usual
time needed for epileptic focus localization in human patients. This is the
first time that single units are recorded along cylindrical polyimide probes
chronically implanted 22 mm deep into the brain of a monkey, which suggests the
potential usefulness of this probe for human applications
Mechanical durability of hydrophobic surfaces fabricated by injection moulding of laser-induced textures
YesThe paper reports an investigation on the mechanical durability of textured thermoplastic surfaces together with their respective wetting properties. A range of laser-induced topographies with different aspect ratios from micro to nanoscale were fabricated on tool steel inserts using an ultrashort pulsed near infrared laser. Then, through micro-injection moulding the topographies were replicated onto polypropylene surfaces and their durability was studied systematically. In particular, the evolution of topographies on textured thermoplastic surfaces together with their wetting properties were investigated after undergoing a controlled mechanical abrasion, i.e. reciprocating dry and wet cleaning cycles. The obtained empirical data was used both to study the effects of cleaning cycles and also to identify cleaning procedures with a minimal impact on textured thermoplastic surfaces and their respective wetting properties. In addition, the use of 3D areal parameters that are standardised and could be obtained readily with any state-of-the-art surface characterisation system are discussed for monitoring the surfaces' functional response.European Commission H2020 ITN programme âEuropean ESRs Network on Short Pulsed Laser Micro/Nanostructuring of Surfaces for Improved Functional Applicationsâ (Laser4Fun) under the Marie SkĹodowska-Curie grant agreement No. 675063 (www.laser4fun.eu) and the UKIERI DST programme âSurface functionalisation for food, packaging, and healthcare applicationsâ. In addition, the work was supported by three other H2020 programmes, i.e. the projects on âModular laser based additive manufacturing platform for large scale industrial applicationsâ (MAESTRO), âHigh-Impact Injection Moulding Platform for mass-production of 3D and/or large micro-structured surfaces with Antimicrobial, Self-cleaning, Anti-scratch, Anti-squeak and Aesthetic functionalitiesâ (HIMALAIA) and âProcess Fingerprint for Zero-defect Net-shape Micromanufacturingâ (MICROMAN)
The ultra-low-frequency shear modes of 2-4 layer graphenes observed in their scroll structures at edges
The in-plane shear modes between neighbor-layers of 2-4 layer graphenes (LGs)
and the corresponding graphene scrolls rolled up by 2-4LGs were investigated by
Raman scattering. In contrast to that just one shear mode was observed in
3-4LGs, all the shear modes of 3-4LGs were observed in 3-4 layer scrolls (LSs),
whose frequencies agree well with the theoretical predication by both a
force-constant model and a linear chain model. In comparison to the broad width
(about 12cm) for the G band in graphite, all the shear modes exhibit an
intrinsic line width of about 1.0 cm. The local electronic structures
dependent on the local staking configurations enhance the intensity of the
shear modes in corresponding 2-4LSs zones, which makes it possible to observe
all the shear modes. It provides a direct evidence that how the band structures
of FLGs can be sensitive to local staking configurations. This result can be
extended to n layer graphene (n > 4) for the understanding of the basic phonon
properties of multi-layer graphenes. This observation of all-scale shear modes
can be foreseen in other 2D materials with similar scroll structures.Comment: 14 pages, 5 figure
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