Pattern Formation Research Articles

Complete Visibility Algorithms of Luminous Robots With Two‐Color Lights on Grid

ABSTRACTAn autonomous mobile robot system is a distributed system consisting of multiple mobile computational entities, called robots, which autonomously and repeatedly perform three fundamental operations: look, compute, and move. Various challenges in such systems, including gathering, pattern formation, and flocking, have been extensively studied to explore the relationship between the robots' capabilities and the feasibility of solving these problems (i.e., solvability). In this study, we focus on the complete visibility problem, which aims to relocate all robots on an infinite grid plane so that every robot is visible to every other robot (i.e., complete visibility). We assume that each robot is a luminous robot (i.e., has a light with a constant number of colors) and opaque (non‐transparent). This paper primarily examines the number of light colors required for each robot to solve the complete visibility problem. Specifically, we investigate the question: “how many colors can we reduce while still achieving complete visibility?” (even under certain stronger assumptions). As an answer to the above question, we show the existence of a deterministic algorithm to achieve complete visibility (i.e., every robot can observe all the other robots) using only two colors of light, if the robots agree on the directions and orientations of both axes. The proposed algorithm correctly works even if robots operate asynchronously and have no knowledge of the total number of robots. Moreover, its spatial complexity (i.e., the area of the smallest enclosed rectangle that includes all robots in the final configuration) ensures the optimal one, , where is the number of robots.

Lateral Phase Heterojunction for Perovskite Microoptoelectronics.

Perovskite heterojunction engineering is the prerequisite but still a deficiency in the fabrication of micro-optoelectronic devices, where the present top-down or bottom-up techniques mainly focus on preparing the vertical heterojunction stacks. Perovskite lateral heterojunction structures generally rely on epitaxial growth, which cannot meet the demands of mass production of micro-devices. Here, a contact diffusion lithography technique is proposed to demonstrate a perovskite lateral phase heterojunction (LPH) polycrystalline film by ion-driven local phase transition. Under the guidance of thermodynamic simulations, methylamine contact and migration collectively promote in situ formation of α-phase formamidine-based perovskite patterns surrounded by δ-phase polymorphs. Spontaneous type-I heterojunction alignment between α- and δ-phases establishes energy funnels in the LPH film to facilitate carrier utilization and radiative recombination. The wide-bandgap δ-phase also serves as the coplanar isolator to achieve local anti-leakage for device integration. Based on the bright and stable LPH pattern layer, the near-infrared microscale perovskite light-emitting diode (micro-PeLED) with impressive device performance is achieved by following conventional device fabrication protocol. The proposed LPH enriches the perovskite heterojunction family, creates a new optoelectronic processing platform, and advances its versatile applications in micro-optoelectronics and photonics.

Role of membrane H+ transport and plasmalemma excitability in pattern formation, long-distance transport and photosynthesis of Characean algae

Illuminated giant cells of Characeae comprise alternating areas with H+ pump activity and zones with high conductivity for H+/OH–, which create counter-directed H+ flows between the medium and the cytoplasm. In areas where H+ enters the cell, the pH on the surface (pHo) increases to pH 10, while the cytoplasmic pH (pHc) decreases. The lack of the permeant substrate of photosynthesis (CO2) and the acidic pHc shift in the region of external alkaline zones redirect electron transport in chloroplasts from CO2-dependent (assimilatory) pathway to O2 reduction. This electron transport route is associated with an increase in thylakoid membrane ΔpH and an enhanced nonphotochemical quenching (NPQ) of chlorophyll excitations, which underlies strict coordination between nonuniform distributions of pHo and photosynthetic activity in resting cells. When the action potential (AP) is generated, the longitudinal pH profile is temporarily smoothed out, while the heterogeneity of the distribution of NPQ and PSII photochemical activity (YII) sharply increases. The damping of the pHo profile is due to the suppression of the H+ pump and passive H+ conductance under the influence of an almost 100-fold increase in the cytoplasmic of Ca2+ level ([Ca2+]c) during AP. The increase in [Ca2+]c stimulates photoreduction of O2 in chloroplasts under external alkaline zones and, at the same time, arrests the cytoplasmic streaming, which causes the accumulation of excess amounts of H2O2 in the cytoplasm in areas of intense production of this metabolite, with a weak effect on areas of CO2 assimilation. These changes enhance the nonuniform distribution of cell photosynthesis and account for the long-term oscillations of chlorophyll fluorescence Fm' and the quantum efficiency of linear electron flow in microscopic cell areas after the AP generation.

Fabrication of Flexible Organic Field Effect Transistor Using Patterned Electrospray Deposition

ABSTRACTThe electrospray deposition (ESD) method is a wet process that uses the solution spray formed by an electric field between the needle of a syringe containing the solution and a conductive substrate or an insulated electrode. In this study, we fabricated thin films based on 6,13‐bis(triisopropyl‐silylethynyl) pentacene (TIPS‐pentacene) formed by a new direct patterning ESD method. This method utilizes an electric field applied between the nozzle and patterned electrodes on the substrate. It enables the formation of patterns on materials such as plastic films. Moreover, this ESD method allows for the control of patterned film width using the voltage on a counter‐patterned electrode. These results demonstrate that the patterned TIPS‐pentacene film width can be controlled by controlling voltage. We fabricated a flexible organic field‐effect transistor (OFET) using this method and measured its static electrical characteristics.

Pattern formation on regular polygons and circles

We investigate the formation of Turing patterns on regular polygonal domains, as the number of edges grow, leading to the limiting case of the circle. Using linear and weakly nonlinear analysis, and evidence by simulations, we demonstrate how the domain shape can fundamentally change the expected bifurcation structure. Specifically, on the square domain we are able to derive pitchfork bifurcations for stripe and spot solutions, as well as show that both branches cannot bifurcate to produce stable patterns. This compares with the case of the equilateral triangle domain that causes the Turing bifurcation to be generically transcritical and, in some cases, none of the bifurcating branches are stable. Moreover, we find a monotonically increasing, but nonlinear relationship, between the minimal bifurcation area and the number of edges. Thus, patterns can occur on triangles with much smaller areas than circles. Overall, this work raises questions for researchers who are simulating applications on domains with simple shapes. Specifically, even small changes to domain geometry can have large impacts on the produced patterns; thus, domain perturbations should be considered in any sensitivity analyses.

Induction of patterns through crowding in a cross-diffusion model

In this paper we focus on pattern formation in systems of interacting populations. We show that if one considers these populations to be “crowded” in a way that is defined below, then cross-diffusion terms appear naturally. Moreover, we show that these additional cross-diffusion terms can generate stable spatial patterns that are not manifest in the corresponding standard “dilute” formulation. This result demonstrates the need for care when choosing standard Fickian diffusion as the default in applications to population dynamics.

Research on identification and zoning control of territorial spatial risk pattern based on deep learning: A case study of Shenzhen, China

In the era of globalization, digitalization, and diversification, currently societal cities face risks intertwined by uncertainty and complexity. Thus, it is crucial to address risks concerns to achieve modernization of spatial management. Moreover, how to scientifically identify the risk pattern of territorial space and how to map and control it in space becomes a critical and urgent issue to be addressed for achieving modernization of spatial management. Understanding the intricate relationship between land use, environmental factors, and population density is essential for identifying risk patterns that can inform effective disaster management strategies. By employing advanced analytical methods, this study aims to provide a comprehensive framework for recognizing and mitigating territorial spatial risks in an increasingly complex urban landscape. This study used a case study to conduct the unsupervised algorithm of stack autoencoder self-organizing map to analyze the distribution and spatial clustering of Shenzhen's land spatial risk pattern and reveal the driving mechanism of its risk pattern formation in detail. It was found that: (1) The overall territorial spatial risk pattern of Shenzhen presents a distribution trend of "high in the west and low in the east, high in the south and low in the north"; that is, I and II risk areas are clustered in the hilly areas in the northeast and IV and V risk areas in the coastal areas in the southwest; (2) Population density, land use intensity, seawater intrusion, geological disasters, relief amplitude, soil type, soil erosion intensity are the main driving forces for the formation of Shenzhen's territorial spatial risk pattern. In particular, seawater intrusion, population density and land use intensity, soil type were found having significantly synergistic impact on the risk pattern.

Slow-fast dynamics in non-linear enzyme cascades gives rise to spatial multiscaling.

Slow-fast dynamics in a well-mixed biological system is known to be associated with functional modularity with temporal hierarchy of processes. Yet, the significance of slow-fast dynamics in spatially distributed reaction-diffusion systems remains to be clarified.We assessed such systems with slow-fast dynamics, such as blood coagulation and predator-prey models to identify spatial patterns with independent parametric regulation, and performed their reaction-rate based sensitivity analysis with the help of computational one-dimensional reaction-diffusion models.In blood coagulation, spatial distribution of fibrin had two scales: a larger region with a high and almost constant fibrin concentration (corresponding to solid blood clot) and a narrow transition zone, where fibrin concentration decayed to zero (semi-liquid clot). Slow variables (e.g., the concentration of the coagulation factor IXa) regulated the clot size (large scale), while fast variables (e.g., concentrations of thrombin and factor Xa) regulated the thickness of the gel-to-liquid transition zone (small scale). Analysis of the simplified model of blood coagulation, composed only of factor X and IX activation, and of the predator-prey model confirmed this finding to be sufficiently general, and revealed that the limitation of fast enzyme production (due to precursor depletion or to kinetics with saturation) was crucial for this multi-scaling. Independent regulation of spatial scales also required species with slow kinetics to be upstream from species with fast kinetics.The shared slow-fast dynamics of the examined systems endow them with the ability to form spatial patterns, representing a new mechanism complementing the Turing-type and the Positional Information type pattern formation.

Facile Formation of Metallic Surface with Microroughness via Spray-Coating of Copper Nanoparticles for Enhanced Liquid Metal Wetting

This paper presents a simple, fast, and cost-effective method for creating metallic microstructured surfaces by spray-coating a dispersion of copper nanoparticles (CuNPs) onto polymethyl methacrylate (PMMA) substrates, enabling the imbibition-induced wetting of liquid metal. The formation of these microstructured patterns is crucial for the spontaneous wetting of gallium-based liquid metals. Traditional techniques for producing such microstructures often involve complex and costly lithography and vacuum deposition methods. In contrast, this study demonstrates that liquid metal wetting can occur with metal microstructures formed through a straightforward spray-coating process. To immobilize the CuNPs on the polymer substrate, an organic solvent that dissolves the polymer surface was employed as the dispersion medium. The effects of various spray-coating parameters, including distance and time, on the uniformity and immobilization of CuNP films were systematically investigated. Under optimal conditions (120 s of spray time and 10 cm spray distance), CuNPs dispersed in dichloromethane (DCM) yielded uniform and stable microstructured surfaces. The spontaneous wetting of gallium-based liquid metal was observed on the fabricated CuNP film. Additionally, liquid metal selectively wet the CuNP patterns formed by stencil techniques, establishing electrical connections between electrodes. These findings underscore the potential of spray-coating for fabricating metallic surfaces to drive the formation of liquid metal patterns in flexible electronics applications.

A three-layer Hele-Shaw problem driven by a sink

In this paper, we investigate a sink-driven three-layer flow in a radial Hele-Shaw cell. The three fluids are of different viscosities, with one fluid occupying an annulus-like domain, forming two interfaces with the other two fluids. Using a boundary integral method and a semi-implicit time stepping scheme, we alleviate the numerical stiffness in updating the interfaces and achieve spectral accuracy in space. The interaction between the two interfaces introduces novel dynamics leading to rich pattern formation phenomena, manifested by two typical events: either one of the two interfaces reaches the sink faster than the other (forming cusp-like morphology), or they come very close to each other (suggesting a possibility of interface merging). In particular, the inner interface can be wrapped by the other to have both scenarios. We find that multiple parameters contribute to the dynamics, including the width of the annular region, the location of the sink, and the mobilities of the fluids.

Nature's All-in-One: Multitasking Robots Inspired by Dung Beetles.

Dung beetles impressively coordinate their 6 legs to effectively roll large dung balls. They can also roll dung balls varying in the weight on different terrains. The mechanisms underlying how their motor commands are adapted to walk and simultaneously roll balls (multitasking behavior) under different conditions remain unknown. This study unravels the mechanisms of how dung beetles roll dung balls and adapt their leg movements to stably roll balls over different terrains for multitasking robots. A modular neural-based loco-manipulation control inspired by and based on ethological observations of the ball-rolling behavior of dung beetles is synthesized. The proposed neural-based control contains a central pattern generator (CPG) module, a pattern formation network (PFN) module, and a robot orientation control (ROC) module. The integrated control mechanisms can control a dung beetle-like robot (ALPHA) with biomechanical feet to perform adaptive (multitasking) loco-manipulation (walking and ball-rolling) on various terrains (flat and uneven). It can deal with different ball weights (2.0 and 4.6kg) and ball types (soft and rigid). The control mechanisms can serve as guiding principles for solving sensory-motor coordination for multitasking robots. Furthermore, this study contributes to biological research by enhancing the understanding of sensory-motor coordination for adaptive (multitasking) loco-manipulation behavior in animals.

Correlation between temperature distribution and changes in self-organized luminous pattern in an atmospheric pressure DC glow discharge by sheath gas flow

Abstract The self-organized luminous patterns observed above the anode surface in atmospheric-pressure DC glow discharges were changed by the composition of the gas flow. The patterns were observed not only with liquid anodes but also with metal anodes. Various pattern structures were observed by changing the helium gas flow rate in the core and the ambient oxygen gas flow rate supplied during the discharge. When the pattern formation was observed, the emission spectra and the radial spread of the positive column changed, and the voltage-current characteristic also changed. These results suggest that not only the anode surface but the entire discharge affects the pattern formation. Comparing the results for the liquid and metal anodes, the trends in the pattern formation and voltage-current characteristics were almost identical. The gas temperature in the discharge was also investigated in two different ways, by the LIF of OH radicals and by Rayleigh scattering, and these two results were in good agreement. Under the condition where the pattern formed, the gas temperature in the discharge was approximately 2500-3000 K and higher than that of the discharge without the pattern formation. Focusing on the gradient of the temperature distribution, the discharge with the pattern formation had a steeper gradient than that of the discharge without the pattern formation. It was suggested that not only the high temperature of the discharge but also the large gradient of the temperature change plays an important role in the pattern formation. The role of oxygen gas in the pattern formation may be the effect of increasing the temperature and altering the temperature gradient in the discharge rather than generating negative ions in the discharge.

Formation and evolution of optical wave patterns in dispersion oscillating tapered fiber for dispersion managed applications

Formation and evolution of optical wave patterns in dispersion oscillating tapered fiber for dispersion managed applications

CircCSPP1 Competitively Binds miR-10a to Regulate BMP7 Expression and Affects the Proliferation of Dermal Papilla Cells

A series of differentially expressed circular RNAs (circRNAs), microRNAs (miRNAs), and messenger RNAs (mRNAs) were identified through sequencing in the hair follicle tissues of Hu sheep with small-waved and straight wool patterns. Based on these findings, the circCSPP1-miR-10a-BMP7 (Bone Morphogenetic Protein 7) regulatory network was constructed. The preliminary study highlighted that miR-10a and the BMP7 gene exhibited not only significant differential expression across hair follicle tissues with different patterns in Hu sheep but also had an impact on the proliferation of hair papilla cells. The proliferation of hair papilla cells is intricately linked to hair follicle development and growth. Consequently, we selected the circCSPP1-miR-10a-BMP7 regulatory network to validate its role in promoting hair papilla cell proliferation in Hu sheep. Firstly, the authenticity of circCSPP1 was successfully confirmed through RNase R digestion and reverse primer amplification. Additionally, nucleoplasmic localization analysis determined that circCSPP1 was predominantly distributed in the cytoplasm. Using the dual-luciferase gene reporter system, we verified the targeting relationship between circCSPP1 and miR-10a, building upon our previous validation of the miR-10a-BMP7 interaction. This clarified the competing endogenous RNA (ceRNA) mechanism within the circCSPP1-miR-10a-BMP7. Furthermore, rescue experiments confirmed that circCSPP1 competitively binds to miR-10a, thereby regulating BMP7 expression and influencing the proliferation of hair papilla cells in Hu sheep. This discovery provides a solid foundation for future investigations into the mechanisms underlying wool curvature and the formation of lambskin patterns, offering insights into the complex regulatory networks that govern these phenotypic traits in Hu sheep.

Влияние избыточной массы тела и ожирения на спирометрические, гематологические показатели, уровень общего иммуноглобулина Е и интерлейкина-6 в сыворотке крови у детей и подростков с бронхиальной астмой

There is undoubtedly insufficient number of studies dedicated to the interleukin-6 (IL-6) in blood serum of children and adolescents with bronchial asthma (BA) and those are contradictory. Connection between the IL-6 serum level and systemic markers of type 2 inflammation in BA in children and adolescents depending on the nutritional status remains a subject to discussion as well. The purpose of this research was to study the effect of excess body weight (BW) and obesity on spirometric, hematological parameters, total immunoglobulin E (IgE), IL-6 levels in blood serum of children and adolescents with BA. Materials and methods used: a single-center observational cross-sectional pilot study of 76 adolescents aged 6 to 17 y/o (75% (57) boys) with BA was conducted. All were measured for anthropometric and spirometric parameters, body composition, hematological parameters, total IgE and IL-6 levels in blood serum. Dysanapsis was diagnosed when three conditions were simultaneously met: 1. high or high-to-normal zFVC (above 0.674), 2. normal zFEV1 (above -1.645), and 3. low FEV1/FVC index (below 80%). Results: the number of monocytes (109/l) in peripheral blood and the serum IL-6 level (pg/ml) were statistically significantly higher in the group of patients with overweight and obesity compared to patients with underweight/normal BW (0.55 [0.49; 0.77] v 0.51 [0.42; 0.58], p=0.043 and 1.99 [1.20; 5.78] v 1.28 [0.31; 2.43], p=0.002, respectively). In patients with excess BW and obesity, an inverse statistically significant relationship was found between the serum IL-6 level, zFEV1/FVC and the dysanapsis ratio (R=-0.53, p=0.009, R=-0.61, p=0.002, respectively). Conclusion: formation of an obstructive pattern in children and adolescents with BA with excess BW and obesity may be associated with non-T2-dependent inflammatory mechanisms.

Electroless Copper Patterning on TiO2-Functionalized Mica for Flexible Electronics

The formation of conductive copper patterns on mica holds promise for developing cost-effective flexible electronics and sensing devices, though it is challenging due to the low adhesion of mica’s atomically flat surface. Herein, we present a wet-chemical method for copper patterning on flexible mica substrates via electroless copper deposition (Cu-ELD). The process involves pre-functionalizing 50 µm thick muscovite mica with a titanium dioxide (TiO2) layer, via a sol–gel dip-coating method with a titanium acetylacetonate-based sol. Photolithography is employed to selectively activate the TiO2-coated mica substrates for Cu-ELD, utilizing in situ photodeposited silver (Ag) nanoclusters as a catalyst. Copper is subsequently plated using a formaldehyde-based Cu-ELD bath, with the duration of deposition primarily determining the thickness and electrical properties of the copper layer. Conductive Cu layers with thicknesses in the 70–130 nm range were formed within 1–2 min of deposition, exhibiting an inverse relationship between plating time and sheet resistance, which ranged from 600 to 300 mΩ/sq. The electrochemical thickening of these layers to 1 μm further reduced the sheet resistance to 27 mΩ/sq. Finally, the potential of Cu-ELD patterning on TiO2-functionalized mica for creating functional sensing devices was demonstrated by fabricating a functional resistance temperature detector (RTD) on the titania surface.

Pattern formations and their actively manipulation in a Rydberg noisy-dressed Bose-Einstein condensates

Pattern formations and their actively manipulation in a Rydberg noisy-dressed Bose-Einstein condensates

Self-assembled micro-patterns in uphill-diffusion solution system.

In this work we present self-organized regular patterns in a solution system through uphill-diffusion. Micrometer thick organic semiconductor solution is sandwiched between a substrate and cover-plate. Self-assembled regular patterns can be observed on the substrate after solvent evaporation. Different micro-patterns and pattern defects were displayed and analyzed. Mechanisms of defect formation, mode selection process during patten generation, and pattern sedimentation onto substrate from solution were proposed. Organic thin film transistors were fabricated with the assembled line patterns which demonstrate a promising way to produce patterned micro/nano materials.

TRNA and tsRNA: From Heterogeneity to Multifaceted Regulators.

As the most ancient RNA, transfer RNAs (tRNAs) play a more complex role than their constitutive function as amino acid transporters in the protein synthesis process. The transcription and maturation of tRNA in cells are subject to stringent regulation, resulting in the formation of tissue- and cell-specific tRNA pools with variations in tRNA overall abundance, composition, modification, and charging levels. The heterogeneity of tRNA pools contributes to facilitating the formation of histocyte-specific protein expression patterns and is involved in diverse biological processes. Moreover, tRNAs can be recognized by various RNase under physiological and pathological conditions to generate tRNA-derived small RNAs (tsRNAs) and serve as small regulatory RNAs in various biological processes. Here, we summarize these recent insights into the heterogeneity of tRNA and highlight the advances in the regulation of tRNA function and tsRNA biogenesis by tRNA modifications. We synthesize diverse mechanisms of tRNA and tsRNA in embryonic development, cell fate determination, and epigenetic inheritance regulation. We also discuss the potential clinical applications based on the new knowledge of tRNA and tsRNA as diagnostic and prognostic biomarkers and new therapeutic strategies for multiple diseases.

Atomistic understanding on the surface formation mechanism of nanoscale scratches along different crystal orientations of silicon carbide

Single crystal silicon carbide has been widely used in many fields due to its excellent physical and chemical properties. However, these special properties of silicon carbide can lead to surface defects and subsurface damage in precision machining processes. In this research, high-speed scratching experiments and molecular dynamics simulations were used to study the surface formation mechanism of nanoscale scratches along the [1-210] and [1-100] crystal orientations of silicon carbide. For both the simulations and experiments, different scratching crystal orientations result in the formation of different amorphous patterns. The angle between the scratching orientation [1-210] and the amorphous pattern is 60°, while the angle between scratching orientation [1-100] and the amorphous pattern is 30°. The stress concentration during the scratching process along the orientations [1-210] and [1-100] is mainly located at the two edges and one edge of the amorphous patterns, respectively. The amorphous patterns along the < 1-210 > directions on the (0001) plane are caused by dislocations and slips on the {10-10} plane. This study reveals the material deformation mechanism and removal mechanism of silicon carbide along different crystal orientations scratching, providing theoretical guidance for the nanoscale machining of silicon carbide.