313 research outputs found
Detection of carbon monoxide and hydrogen with non-stoichiometric perovskites, and variation in transduction modes
Peer reviewed: YesNRC publication: Ye
Strong Bulk Photovoltaic Effect in Planar Barium Titanate Thin Films
The bulk photovoltaic effect (BPE) leads to the generation of a photocurrent
from an asymmetric material. Despite drawing much attention due to its ability
to generate photovoltages above the band gap (), it is considered a weak
effect due to the low generated photocurrents. Here, we show that a remarkably
high photoresponse can be achieved by exploiting the BPE in simple planar
BaTiO (BTO) films, solely by tuning their fundamental ferroelectric
properties via strain and growth orientation induced by epitaxial growth on
different substrates. We find a non-monotonic dependence of the responsivity
() on the ferroelectric polarization () and obtain a remarkably
high BPE coefficient () of 10 1/V, which to the best of
our knowledge is the highest reported to date for standard planar BTO thin
films. We show that the standard first-principles-based descriptions of BPE in
bulk materials cannot account for the photocurrent trends observed for our
films and therefore propose a novel mechanism that elucidates the fundamental
relationship between and responsivity in ferroelectric thin films. Our
results suggest that practical applications of ferroelectric photovoltaics in
standard planar film geometries can be achieved through careful joint
optimization of the bulk structure, light absorption, and electrode-absorber
interface properties.Comment: 12 pages, 8 figure
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An Enhanced Tilted-Angle Acoustofluidic Chip for Cancer Cell Manipulation
In recent years, surface acoustic wave (SAW) devices have demonstrated great potentials and increasing applications in the manipulation of nano- and micro-particles including biological cells with the advantages of label-free, high sensitivity and accuracy. In this letter, we introduce a novel tilted-angle SAW devices to optimise the acoustic pressure inside a microchannel for cancer-cell manipulation. The SAW generation and acoustic radiation force are improved by seamlessly patterning electrodes in the space surrounding the microchannel. Comparisons between this novel SAW device and a conventional device show a 32% enhanced separation efficiency while the input power, manufacturing cost and fabrication effort remain the same. Effective separation of HeLa cancer cells from peripheral blood mononuclear cells is demonstrated. This novel SAW device has the advantages in minimizing device power consumption, lowering component footprint and increasing device density.This work was supported by the Natural Science Basic Research Program of Shaanxi Province (2020JQ-233); Fundamental Scientific Research of Central Universities (grant number 3102017OQD116); the Engineering and Physical Sciences Research Council (EPSRC) (EP/P002803/1 and EP/P018998/1); and the Royal Society (IEC/NSFC/170142, IE161019)
SPH study of the evolution of water–water interfaces in dam break flows
The mixing process of upstream and downstream waters in the dam break flow could
generate significant ecological impact on the downstream reaches and influence the
environmental damages caused by the dam break flood. This is not easily investigated with
the analytical and numerical models based on the grid method due to the large deformation of
free surface and the water-water interface. In this paper, a weakly compressible Smoothed
Particle Hydrodynamics (WCSPH) solver is used to study the advection and mixing process
of the water bodies in two-dimensional dam-break flows over a wet bed. The numerical
results of the mixing dynamics immediately after the release of the dam water are found to
agree satisfactorily with the published experimental and numerical results. Then further
investigations are carried out to study the interface development at the later stage of dambreak
flows in a long channel. The analyses concentrate on the evolution of the interface at
different ratios between the upstream and downstream water depths. The potential
capabilities of the mesh-free SPH modelling approach for predicting the detailed
development of the water-water interfaces are fully demonstrated.The first author acknowledges the Jafar Studentship during her PhD study at the University of
Cambridge. The other authors acknowledge the support of the
Major State Basic Research Development Program (973) of China (No. 2013CB036402),
Open Fund of the State Key Laboratory of Hydraulics and Mountain River Engineering,
Sichuan University (SKHL1404; SKHL1409), Start-up Grant for the Young Teachers of
Sichuan University (2014SCU11056) and National Science and Technology Support Plan
(2012BAB0513B0).This is the accepted manuscript. The final version is available at http://link.springer.com/article/10.1007%2Fs11069-015-1726-6
Team Dynamics Theory: Nomological network among cohesion, team mental models, coordination, and collective efficacy
I put forth a theoretical framework, namely Team Dynamics Theory (TDT), to address the need for a parsimonious yet integrated, explanatory and systemic view of team dynamics. In TDT, I integrate team processes and outputs and explain their relationships within a systemic view of team dynamics. Specifically, I propose a generative nomological network linking cohesion, team mental models, coordination, collective efficacy, and team outcomes. From this nomological conceptualization, I illustrate how myriad alternative models can be derived to account for variance in different working teams, each comprised of unique members, and embedded in singular contexts. I outline TDT’s applied implications for team development, the enhancement of team functioning, and the profiling of team resilience. I conclude by discussing how TDT’s ontological and nomological propositions can be tested through various theoretical inquiries, methodological approaches, and intervention-based studies
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