Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Topology-dependent self-structure mediation and efficient energy conversion in heat-flux-driven rotors of cholesteric droplets.

ABSTRACT: When heat flux is applied to a chiral liquid crystal, unidirectional rotation is induced around the flux axis, as first discovered by Otto Lehmann in 1900. In recent years, this heat-flux-induced phenomenon has been studied mostly in droplets of cholesteric liquid crystals undergoing phase transition from the isotropic to cholesteric phase, i.e., in the coexistence region, which occurs over a very narrow temperature range. Here, we report that the heat-flux-induced rotation can be stabilised by the use of a dispersion system, in which the cholesteric droplets are dispersed in a viscous and poorly miscible isotropic solvent. Interestingly, the phenomenon is found to be topology dependent. Moreover, the rotation is not only stable but also more efficient than that in the known systems. We describe in detail how the dynamics of the heat-flux-induced rotation are altered in the present dispersion system.

SUBMITTER: Yoshioka J

PROVIDER: S-EPMC5789817 | biostudies-other | 2018 Jan

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Publications

Topology-dependent self-structure mediation and efficient energy conversion in heat-flux-driven rotors of cholesteric droplets.

Yoshioka Jun J Araoka Fumito F

Nature communications 20180130 1

When heat flux is applied to a chiral liquid crystal, unidirectional rotation is induced around the flux axis, as first discovered by Otto Lehmann in 1900. In recent years, this heat-flux-induced phenomenon has been studied mostly in droplets of cholesteric liquid crystals undergoing phase transition from the isotropic to cholesteric phase, i.e., in the coexistence region, which occurs over a very narrow temperature range. Here, we report that the heat-flux-induced rotation can be stabilised by ...[more]

PMID: 29382841

Similar Datasets

Shaping nanoparticle fingerprints at the interface of cholesteric droplets.

Project description:The ordering of nanoparticles into predetermined configurations is of importance to the design of advanced technologies. Here, we balance the interfacial energy of nanoparticles against the elastic energy of cholesteric liquid crystals to dynamically shape nanoparticle assemblies at a fluid interface. By adjusting the concentration of surfactant that plays the dual role of tuning the degree of nanoparticle hydrophobicity and altering the molecular anchoring of liquid crystals, we pattern nanoparticles at the interface of cholesteric liquid crystal emulsions. In this system, interfacial assembly is tempered by elastic patterns that arise from the geometric frustration of confined cholesterics. Patterns are tunable by varying both surfactant and chiral dopant concentrations. Adjusting the particle hydrophobicity more finely by regulating the surfactant concentration and solution pH further modifies the rigidity of assemblies, giving rise to surprising assembly dynamics dictated by the underlying elasticity of the cholesteric. Because particle assembly occurs at the interface with the desired structures exposed to the surrounding water solution, we demonstrate that particles can be readily cross-linked and manipulated, forming structures that retain their shape under external perturbations. This study serves as a foundation for better understanding inter-nanoparticle interactions at interfaces by tempering their assembly with elasticity and for creating materials with chemical heterogeneity and linear, periodic structures, essential for optical and energy applications.

| S-EPMC6184783 | biostudies-literature

Optical Textures and Orientational Structures in Cholesteric Droplets with Conical Boundary Conditions.

Project description:Cholesteric droplets dispersed in polymer with conical boundary conditions have been studied. The director configurations are identified by the polarising microscopy technique. The axisymmetric twisted axial-bipolar configuration with the surface circular defect at the droplet's equator is formed at the relative chirality parameter N 0 ? 2.9 . The intermediate director configuration with the deformed circular defect is realised at 2.9 < N 0 < 3.95 , and the layer-like structure with the twisted surface defect loop is observed at N 0 ? 3.95 . The cholesteric layers in the layer-like structure are slightly distorted although the cholesteric helix is untwisted.

| S-EPMC7181251 | biostudies-literature

Effect of elastic constants on electrically induced transition in twisted radial cholesteric droplets.

Project description:In this work, we investigated the behavior of cholesteric droplets with homeotropic boundary conditions experimentally and by computer simulations. Small droplets forming twisted radial structures were studied. We obtained two different paths of structural transformations under electric field in such droplets. The choice between these paths has probabilistic nature. The ratio between the two transition types was found to be sensitive to the elastic constants of LC forming the droplet. We suggest the principal approach for in situ estimation of ratios between elastic constants in cholesteric LCs deposited in polymer-dispersed LC material and discuss its strong and weak sides.

| S-EPMC9187752 | biostudies-literature

Photo-controllable rotational motion of cholesteric liquid crystalline droplets in a dispersion system.

Project description:A photo-controllable rotational motion was demonstrated for an isolated cholesteric liquid crystalline droplet in a surfactant solution. The droplet showed unidirectional rigid-body rotation with UV light irradiation and the rotational rate could be controlled by the light intensity. Furthermore, the rotational direction could be controlled by the chirality of dopants. The motion was explained by the rotational torque induced by the photo-induced gradient of chemical concentrations and/or temperature inside the droplet from the theory of the Lehmann effect, and the possible mechanisms are discussed.

| S-EPMC9054377 | biostudies-literature

The vortex-driven dynamics of droplets within droplets.

Project description:Understanding the fluid-structure interaction is crucial for an optimal design and manufacturing of soft mesoscale materials. Multi-core emulsions are a class of soft fluids assembled from cluster configurations of deformable oil-water double droplets (cores), often employed as building-blocks for the realisation of devices of interest in bio-technology, such as drug-delivery, tissue engineering and regenerative medicine. Here, we study the physics of multi-core emulsions flowing in microfluidic channels and report numerical evidence of a surprisingly rich variety of driven non-equilibrium states (NES), whose formation is caused by a dipolar fluid vortex triggered by the sheared structure of the flow carrier within the microchannel. The observed dynamic regimes range from long-lived NES at low core-area fraction, characterised by a planetary-like motion of the internal drops, to short-lived ones at high core-area fraction, in which a pre-chaotic motion results from multi-body collisions of inner drops, as combined with self-consistent hydrodynamic interactions. The onset of pre-chaotic behavior is marked by transitions of the cores from one vortex to another, a process that we interpret as manifestations of the system to maximize its entropy by filling voids, as they arise dynamically within the capsule.

| S-EPMC7782531 | biostudies-literature

Near-field thermophotovoltaics for efficient heat to electricity conversion at high power density.

Project description:Thermophotovoltaic approaches that take advantage of near-field evanescent modes are being actively explored due to their potential for high-power density and high-efficiency energy conversion. However, progress towards functional near-field thermophotovoltaic devices has been limited by challenges in creating thermally robust planar emitters and photovoltaic cells designed for near-field thermal radiation. Here, we demonstrate record power densities of ~5 kW/m2 at an efficiency of 6.8%, where the efficiency of the system is defined as the ratio of the electrical power output of the PV cell to the radiative heat transfer from the emitter to the PV cell. This was accomplished by developing novel emitter devices that can sustain temperatures as high as 1270 K and positioning them into the near-field (<100 nm) of custom-fabricated InGaAs-based thin film photovoltaic cells. In addition to demonstrating efficient heat-to-electricity conversion at high power density, we report the performance of thermophotovoltaic devices across a range of emitter temperatures (~800 K-1270 K) and gap sizes (70 nm-7 µm). The methods and insights achieved in this work represent a critical step towards understanding the fundamental principles of harvesting thermal energy in the near-field.

| S-EPMC8285488 | biostudies-literature

Conversion of Continuous-Valued Deep Networks to Efficient Event-Driven Networks for Image Classification.

Project description:Spiking neural networks (SNNs) can potentially offer an efficient way of doing inference because the neurons in the networks are sparsely activated and computations are event-driven. Previous work showed that simple continuous-valued deep Convolutional Neural Networks (CNNs) can be converted into accurate spiking equivalents. These networks did not include certain common operations such as max-pooling, softmax, batch-normalization and Inception-modules. This paper presents spiking equivalents of these operations therefore allowing conversion of nearly arbitrary CNN architectures. We show conversion of popular CNN architectures, including VGG-16 and Inception-v3, into SNNs that produce the best results reported to date on MNIST, CIFAR-10 and the challenging ImageNet dataset. SNNs can trade off classification error rate against the number of available operations whereas deep continuous-valued neural networks require a fixed number of operations to achieve their classification error rate. From the examples of LeNet for MNIST and BinaryNet for CIFAR-10, we show that with an increase in error rate of a few percentage points, the SNNs can achieve more than 2x reductions in operations compared to the original CNNs. This highlights the potential of SNNs in particular when deployed on power-efficient neuromorphic spiking neuron chips, for use in embedded applications.

| S-EPMC5770641 | biostudies-literature

Cholesteric Flakes in Motion Driven by the Elastic Force from Nematic Liquid Crystals.

Project description:The paper presents a methodology to control the motion and orientation of suspended reflective cholesteric flakes in a nematic liquid crystal (LC) matrix. The flakes exhibit a dielectric anisotropy which controls their alignment with their in-plane axes parallel to an external electrical dc field. The elastic forces imposed by the LC host affect the switching behavior of the flakes and take care of the realignment to the planar state as soon as the dc field is switched off. When the LC host has a positive dielectric anisotropy, the switching voltage of the flakes is reduced by a factor of 2 in comparison with a LC host with negative dielectric anisotropy or in comparison with an isotropic host. We discovered that the LC host further regulates the back relaxation of cholesteric to return to the planar state upon retrieving the electric field. Whereas, in the isotropic fluid, flakes do not exhibit a preferred orientation when relaxed. Based on this newly proposed principle, we demonstrated its application as an optical switch for smart windows. Depending on the pitch of the cholesteric helix of the flakes, the light of a preset wavelength is reflected. Upon application of an electric field, the embedded flakes rotate their planes perpendicular to the substrate and consequently the incident light becomes fully transmitted without reflection or scattering of light.

| S-EPMC6823640 | biostudies-literature

Indirect optical trapping using light driven micro-rotors for reconfigurable hydrodynamic manipulation.

Project description:Optical tweezers are a highly versatile tool for exploration of the mesoscopic world, permitting non-contact manipulation of nanoscale objects. However, direct illumination with intense lasers restricts their use with live biological specimens, and limits the types of materials that can be trapped. Here we demonstrate an indirect optical trapping platform which circumvents these limitations by using hydrodynamic forces to exert nanoscale-precision control over aqueous particles, without directly illuminating them. Our concept is based on optically actuated micro-robotics: closed-loop control enables highly localised flow-fields to be sculpted by precisely piloting the motion of optically-trapped micro-rotors. We demonstrate 2D trapping of absorbing particles which cannot be directly optically trapped, stabilise the position and orientation of yeast cells, and demonstrate independent control over multiple objects simultaneously. Our work expands the capabilities of optical tweezers platforms, and represents a new paradigm for manipulation of aqueous mesoscopic systems.

| S-EPMC6418258 | biostudies-literature

Swimming droplets driven by a surface wave.

Project description:Self-propelling motion is ubiquitous for soft active objects such as crawling cells, active filaments, and liquid droplets moving on surfaces. Deformation and energy dissipation are required for self-propulsion of both living and non-living matter. From the perspective of physics, searching for universal laws of self-propelled motions in a dissipative environment is worthwhile, regardless of the objects' details. In this article, we propose a simple experimental system that demonstrates spontaneous migration of a droplet under uniform mechanical agitation. As we vary control parameters, spontaneous symmetry breaking occurs sequentially, and cascades of bifurcations of the motion arise. Equations describing deformable particles and hydrodynamic simulations successfully describe all of the observed motions. This system should enable us to improve our understanding of spontaneous motions of self-propelled objects.

| S-EPMC4338424 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data