1,347 research outputs found
Driving dynamic colloidal assembly using eccentric self-propelled colloids
Designing protocols to dynamically direct the self-assembly of colloidal
particles has become an important direction in soft matter physics because of
the promising applications in fabrication of dynamic responsive functional
materials. Here using computer simulations, we found that in the mixture of
passive colloids and eccentric self-propelled active particles, when the
eccentricity and self-propulsion of active particles are high enough, the
eccentric active particles can push passive colloids to form a large dense
dynamic cluster, and the system undergoes a novel dynamic demixing transition.
Our simulations show that the dynamic demixing occurs when the eccentric active
particles move much faster than the passive particles such that the dynamic
trajectories of different active particles can overlap with each other while
passive particles are depleted from the dynamic trajectories of active
particles. Our results suggest that this is in analogy to the entropy driven
demixing in colloid-polymer mixtures, in which polymer random coils can overlap
with each other while deplete the colloids. More interestingly, we find that by
fixing the passive colloid composition at certain value, with increasing the
density, the system undergoes an intriguing re-entrant mixing, and the demixing
only occurs within certain intermediate density range. This suggests a new way
of designing active matter to drive the self-assembly of passive colloids and
fabricate dynamic responsive materials.Comment: Accepted in Soft Matter. Supplementary information can found at
https://www.dropbox.com/sh/xb3u5iaoucc2ild/AABFUyqjXips7ewaie2rFbj_a?dl=
Self-Assembled Chiral Photonic Crystals From Colloidal Helices Racemate
Chiral crystals consisting of micro-helices have many optical properties
while presently available fabrication processes limit their large-scale
applications in photonic devices. Here, by using a simplified simulation
method, we investigate a bottom-up self-assembly route to build up helical
crystals from the smectic monolayer of colloidal helices racemate. With
increasing the density, the system undergoes an entropy-driven
co-crystallization by forming crystals of various symmetries with different
helical shapes. In particular, we identify two crystals of helices arranged in
the binary honeycomb and square lattices, which are essentially composed by two
sets of opposite-handed chiral crystal. Photonic calculations show that these
chiral structures can have large complete photonic bandgaps. In addition, in
the self-assembled chiral square crystal, we also find dual polarization
bandgaps that selectively forbid the propagation of circularly polarized lights
of a specific handedness along the helical axis direction. The self-assembly
process in our proposed system is robust, suggesting possibilities of using
chiral colloids to assemble photonic metamaterials.Comment: Accepted in ACS Nan
The research infrastructure of Chinese foundations, a database for Chinese civil society studies
This paper provides technical details and user guidance on the Research Infrastructure of Chinese Foundations (RICF), a database of Chinese foundations, civil society, and social development in general. The structure of the RICF is deliberately designed and normalized according to the Three Normal Forms. The database schema consists of three major themes: foundations’ basic organizational profile (i.e., basic profile, board member, supervisor, staff, and related party tables), program information (i.e., program information, major program, program relationship, and major recipient tables), and financial information (i.e., financial position, financial activities, cash flow, activity overview, and large donation tables). The RICF’s data quality can be measured by four criteria: data source reputation and credibility, completeness, accuracy, and timeliness. Data records are properly versioned, allowing verification and replication for research purposes
A Improved Particle Swarm Optimization Algorithm with Dynamic Acceleration Coefficients
Particle swarm optimization (PSO) is one of the famous heuristic methods. However, this method may suffer to trap at local minima especially for multimodal problem. This paper proposes a modified particle swarm optimization with dynamic acceleration coefficients (ACPSO). To efficiently control the local search and convergence to the global optimum solution, dynamic acceleration coefficients are introduced to PSO. To improve the solution quality and robustness of PSO algorithm, a new best mutation method is proposed to enhance the diversity of particle swarm and avoid premature convergence. The effectiveness of ACPSO algorithm is tested on different benchmarks. Simulation results found that the proposed ACPSO algorithm has good solution quality and more robust than other methods reported in previous work
Non-Equilibrium Structural and Dynamic Behaviors of Polar Active Polymer Controlled by Head Activity
Thermodynamic behavior of polymer chains out of equilibrium is a fundamental
problem in both polymer physics and biological physics. By using molecular
dynamics simulation, we discover a general non-equilibrium mechanism that
controls the conformation and dynamics of polar active polymer, i.e., head
activity commands the overall chain activity, resulting in re-entrant swelling
of active chains and non-monotonic variation of Flory exponent . These
intriguing phenomena lie in the head-controlled railway motion of polar active
polymer, from which two oppose non-equilibrium effects emerge, i.e., dynamic
chain rigidity and the involution of chain conformation characterized by the
negative bond vector correlation. The competition between these two effects
determines the polymer configuration. Moreover, we identify several generic
dynamic features of polar active polymers, i.e., linear decay of the end-to-end
vector correlation function, polymer-size dependent crossover from ballistic to
diffusive dynamics, and a polymer-length independent diffusion coefficient that
is sensitive to head activity. A simple dynamic theory is proposed to
faithfully explain these interesting dynamic phenomena. This sensitive
structural and dynamical response of active polymer to its head activity
provides us a practical way to control active-agents with applications in
biomedical engineering.Comment: 9 pages, 5 figure
Self-Organized Time Crystal in Driven-Dissipative Quantum System
Continuous time crystals (CTCs) are characterized by sustained oscillations
that break the time translation symmetry. Since the ruling out of equilibrium
CTCs by no-go theorems, the emergence of such dynamical phases has been
observed in various driven-dissipative quantum platforms. The current
understanding of CTCs is mainly based on mean-field (MF) theories, which fail
to address the problem of whether the long-range time crystalline order exists
in noisy, spatially extended systems without the protection of all-to-all
couplings. Here, we propose a new kind of CTC realized in a quantum contact
model through self-organized bistability (SOB). The exotic CTCs stem from the
interplay between collective dissipation induced by the first-order absorbing
phase transitions (APTs) and slow constant driving provided by an incoherent
pump. The stability of such oscillatory phases in finite dimensions under the
action of intrinsic quantum fluctuations is scrutinized by the functional
renormalization group method and numerical simulations. Occurring at the edge
of quantum synchronization, the CTC phase exhibits an inherent period and
amplitude with a coherence time diverging with system size, thus also
constituting a boundary time crystal (BTC). Our results serve as a solid route
towards self-protected CTCs in strongly interacting open systems.Comment: 15 pages, 7 figure
Online near-infrared analysis coupled with MWPLS and SiPLS models for the multi-ingredient and multi-phase extraction of licorice (Gancao)
Additional file 1. Table S1. The sampling intervals in different extraction phases. Table S2. The HPLC results of different indicators. Table S3. The evaluation parameters of PLS and SiPLS models
Transformable Super-Isostatic Crystals Self-Assembled from Segment Colloidal Rods
Colloidal particles can spontaneously self-assemble into ordered structures,
which not only can manipulate the propagation of light, but also vibration or
phonons. Using Monte Carlo simulation, we study the self-assembly of perfectly
aligned segment rod particles with lateral flat cutting. Under the help of
surface attractions, we find that particles with different cutting degree can
self-assemble into different crystal phases characterized by bond coordination
that varies from 3 to 6. Importantly, we identify a transformable
super-isostatic structures with \emph{pgg} symmetry and redundant bonds
(). We find that this structure can support either the soft bulk model or
soft edge model depending on its Poisson's ratio which can be tuned from
positive to negative by a uniform soft deformation. Importantly, the bulk soft
modes are associated with states of self-stress along the direction of zero
strain during the uniform soft deformation. This self-assembled transformable
super-isostatic structure may act as mechanical metamaterials with potential
application in micro-mechanical engineering.Comment: 11pages,5 figure
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