25 research outputs found
Presentation and characterization of novel thick-film PZT microactuators.
International audienceWe propose in this paper the characterization of a new generation of piezoelectric cantilevers called thick-films piezoelectric actuators. Based on the bonding and thinning process of a bulk PZT layer onto a silicon layer, these cantilevers can provide better static and dynamic performances compared to traditional piezocantilevers, additionally to the small dimensions
Many-body tunneling dynamics of Bose-Einstein condensates and vortex states in two spatial dimensions
In this work, we study the out-of-equilibrium many-body tunneling dynamics of
a Bose-Einstein condensate in a two-dimensional radial double well. We
investigate the impact of interparticle repulsion and compare the influence of
angular momentum on the many-body tunneling dynamics. Accurate many-body
dynamics are obtained by solving the full many-body Schr\"odinger equation. We
demonstrate that macroscopic vortex states of definite total angular momentum
indeed tunnel and that, even in the regime of weak repulsions, a many-body
treatment is necessary to capture the correct tunneling dynamics. As a general
rule, many-body effects set in at weaker interactions when the tunneling system
carries angular momentum.Comment: 26 pages, 9 figure
Scalable production of graphene inks via wet-jet milling exfoliation for screen-printed micro-supercapacitors
The miniaturization of energy storage units is pivotal for the development of
next-generation portable electronic devices. Micro-supercapacitors (MSCs) hold
a great potential to work as on-chip micro-power sources and energy storage
units complementing batteries and energy harvester systems. The scalable
production of supercapacitor materials with cost-effective and high-throughput
processing methods is crucial for the widespread application of MSCs. Here, we
report wet-jet milling exfoliation of graphite to scale-up the production of
graphene as supercapacitor material. The formulation of aqueous/alcohol-based
graphene inks allows metal-free, flexible MSCs to be screen-printed. These MSCs
exhibit areal capacitance (Careal) values up to 1.324 mF cm-2 (5.296 mF cm-2
for a single electrode), corresponding to an outstanding volumetric capacitance
(Cvol) of 0.490 F cm-3 (1.961 F cm-3 for a single electrode). The
screen-printed MSCs can operate up to power density above 20 mW cm-2 at energy
density of 0.064 uWh cm-2. The devices exhibit excellent cycling stability over
charge-discharge cycling (10000 cycles), bending cycling (100 cycles at bending
radius of 1 cm) and folding (up to angles of 180{\deg}). Moreover, ethylene
vinyl acetate-encapsulated MSCs retain their electrochemical properties after a
home-laundry cycle, providing waterproof and washable properties for
prospective application in wearable electronics
Progress in upscaling Miscanthus biomass production for the European bio-economy with seed-based hybrids
Funded by UK's Biotechnology and Biological Sciences Research Council (BBSRC) Department for Environment, Food and Rural Affairs (DEFRA). Grant Number: LK0863 BBSRC strategic programme Grant on Energy Grasses & Bio-refining. Grant Number: BBS/E/W/10963A01 OPTIMISC. Grant Number: FP7-289159 WATBIO. Grant Number: FP7-311929 Innovate UK/BBSRC âMUSTâ. Grant Number: BB/N016149/1Peer reviewedPublisher PD
Insights from in\ua0vivo micro-CT analysis: testing the hydraulic vulnerability segmentation in Acer pseudoplatanus and Fagus sylvatica seedlings
The seedling stage is the most susceptible one during a tree\u2032s life. Water relations may be crucial for seedlings due to their small roots, limited water buffers and the effects of drought on water transport. Despite obvious relevance, studies on seedling xylem hydraulics are scarce as respective methodical approaches are limited.
Micro\u2010CT scans of intact Acer pseudoplatanus and Fagus sylvatica seedlings dehydrated to different water potentials (\u3a8) allowed the simultaneous observation of gas\u2010filled versus water\u2010filled conduits and the calculation of percentage loss of conductivity (PLC) in stems, roots and leaves (petioles or main veins). Additionally, anatomical analyses were performed and stem PLC measured with hydraulic techniques.
In A. pseudoplatanus, petioles showed a higher \u3a8 at 50% PLC (\u3a850 121.13MPa) than stems ( 122.51 MPa) and roots ( 121.78 MPa). The main leaf veins of F. sylvatica had similar \u3a850 values ( 122.26 MPa) to stems ( 122.74 MPa) and roots ( 122.75 MPa). In both species, no difference between root and stems was observed. Hydraulic measurements on stems closely matched the micro\u2010CT based PLC calculations.
Micro\u2010CT analyses indicated a species\u2010specific hydraulic architecture. Vulnerability segmentation, enabling a disconnection of the hydraulic pathway upon drought, was observed in A. pseudoplatanus but not in the especially shade\u2010tolerant F. sylvatica. Hydraulic patterns could partly be related to xylem anatomical traits