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

Edge Manipulations for the Maximum Vertex-Weighted Bipartite b-matching

In this paper, we explore the Mechanism Design aspects of the Maximum Vertex-weighted $b$-Matching (MVbM) problem on bipartite graphs $(A\cup T, E)$. The set $A$ comprises agents, while $T$ represents tasks. The set $E$ is the private information of either agents or tasks. In this framework, we investigate three mechanisms - \MB, \MD, and \MG - that, given an MVbM problem as input, return a $b$-matching. We examine scenarios in which either agents or tasks are strategic and report their adjacent edges to one of the three mechanisms. In both cases, we assume that the strategic entities are bounded by their statements: they can hide edges, but they cannot report edges that do not exist. First, we consider the case in which agents can manipulate. In this framework, \MB and \MD are optimal but not truthful. By characterizing the Nash Equilibria induced by \MB and \MD, we reveal that both mechanisms have a Price of Anarchy ($PoA$) and Price of Stability ($PoS$) of $2$. These efficiency guarantees are tight; no deterministic mechanism can achieve a lower $PoA$ or $PoS$. In contrast, the third mechanism, \MG, is not optimal, but truthful and its approximation ratio is $2$. We demonstrate that this ratio is optimal; no deterministic and truthful mechanism can outperform it. We then shift our focus to scenarios where tasks can exhibit strategic behaviour. In this case, \MB, \MD, and \MG all maintain truthfulness, making \MB and \MD truthful and optimal mechanisms. In conclusion, we investigate the manipulability of \MB and \MD through experiments on randomly generated graphs. We observe that (1) \MB is less prone to be manipulated by the first agent than \MD (2) \MB is more manipulable on instances in which the total capacity of the agents is equal to the number of tasks (3) randomizing the agents' order reduces the agents' ability to manipulate \MB.Comment: 37 pages, 6 figures. arXiv admin note: substantial text overlap with arXiv:2307.1230

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

Role of protein acetylation, formation and dispersal of biofilms, and their impact on insects

Bacterial biofilms form on liquid/air and liquid/solid surfaces and consist of cells combined with an extracellular matrix such as exopolysaccharides, extracellular DNA, and glycoproteins. Bacteria have up to a 1000-fold increase of antibiotic resistance in biofilms compared to planktonic cells. Furthermore, biofilm cells show better tolerance to adverse environmental conditions such as nutrition limitations, temperature changes, pH changes, and non-optimal osmotic conditions. In Escherichia coli, the outer membrane protein OmpA increased biofilm formation on polystyrene, polypropylene, and polyvinyl chloride surfaces while it decreased biofilm formation on glass surfaces. This surface-dependent phenotype was because OmpA inhibits cellulose production by inducing the CpxRA two-component signal transduction pathway, and cellulose inhibits biofilm formation on plastic due to its hydrophilic nature. We discovered, and then engineered, BdcA (formerly YjgI), for biofilm dispersal. We found that in E. coli, BdcA increases motility and extracellular DNA production while it decreases exopolysaccharide production, cell length, and aggregation. We reasoned that the 3, 5-cyclic diguanylic acid (c-di-GMP) levels increase upon deleting bdcA, and showed that BdcA binds c-di-GMP in vitro. In addition, we used protein engineering to evolve BdcA for greater c-di-GMP binding and found that the single amino acid change E50Q causes nearly complete biofilm dispersal. We isolated Proteus mirabilis from the blowfly Lucilia sericata, which swarmed significantly. By motility screening and complementation with putative interkingdom signal molecules that have been shown to attract flies, we found lactic acid, phenol, NaOH, KOH, putrescine, and ammonia restore the swarming motility of seven different swarming deficient mutants. These mutants and putative signal molecules will be further tested for fly attraction and oviposition. Acetylation of lysine residues is conserved in all three kingdoms although its role in bacteria is not clear. We demonstrated that acetylation enables E. coli to withstand environmental stresses. Specifically, the bacteria became more resistant to heat and oxidative stress. Furthermore, we showed that the increase in oxidative stress resistance is due to the induction of catalase gene katG. Hence we demonstrate for the first time a specific physiological role for acetylation in prokaryotes

Phase Structure of Compact Star in Modified Quark-Meson Coupling Model

The K$^-$ condensation and quark deconfinement phase transitions are investigated in the modified quark-meson coupling model. It is shown that K$^-$ condensation is suppressed because of the quark deconfinement when $B^{1/4}<$202.2MeV, where $B$ is the bag constant for unpaired quark matter. With the equation of state (EOS) solved self-consistently, we discuss the properties of compact stars. We find that the EOS of pure hadron matter with condensed K$^-$ phase should be ruled out by the redshift for star EXO0748-676, while EOS containing unpaired quark matter phase with $B^{1/4}$ being about 180MeV could be consistent with this observation and the best measured mass of star PSR 1913+16. We then probe into the change of the phase structures in possible compact stars with deconfinment phase as the central densities increase. But if the recent inferred massive star among Terzan 5 with M$>$1.68M$_{\odot}$ is confirmed, all the present EOSes with condensed phase and deconfined phase would be ruled out and therefore these exotic phases are unlikely to appear within neutron stars.Comment: 11 pages, 5 figure

Poly[μ2-aqua-[μ2-1,1′-(butane-1,4-di­yl)diimidazole]bis­(μ4-naphthalene-1,4-dicarboxyl­ato)dimanganese(II)]

In the title compound, [Mn2(C12H6O4)2(C10H14N4)(H2O)]n or [Mn2(1,4-ndc)2(L)(H2O)]n, where 1,4-ndc is naphthalene-1,4-dicarboxyl­ate and L is 1,1′-(butane-1,4-di­yl)diimidazole, the coordination polyhedron around each MnII atom is distorted octa­hedral. The water mol­ecule and the L ligand are situated across a twofold rotation axis. The MnII atoms are bridged by 1,4-ndc and L ligands, forming a three-dimensional network. O—H⋯O hydrogen bonds are observed within the network

Poly[μ-aqua-[μ-1,1′-(butane-1,4-di­yl)diimidazole]bis­(μ4-naphthalene-1,4-dicarboxyl­ato)dicadmium(II)]

In the title compound, [Cd2(C12H6O4)2(C10H14N4)(H2O)]n, the coordination polyhedron around each CdII ion is a distorted CdNO5 octa­hedron. The water O atom has site symmetry 2 and the complete 1,1′-(butane-1,4-di­yl)diimidazole (L) ligand is generated by inversion. The naphthalene-1,4-dicarboxyl­ate and L ligands bridge the metal centres, forming a three-dimensional framework, which is consolidated by O—H⋯O hydrogen bonds