Cooperative Phenomena Research Articles

Progress and challenges in the synthesis of two-dimensional Van der Waals ferroic materials and heterostructures

Abstract Two-dimensional ferroelectric and magnetic van der Waals materials are emergent platforms for the discovery of novel cooperative quantum phenomena and development of energy-efficient logic and memory applications as well as neuromorphic and topological computing. This review presents a comprehensive survey of the rapidly growing 2D ferroic family from the synthesis perspective, including brief introductions to the top-down and bottom-up approaches for fabricating 2D ferroic flakes, thin films, and heterostructures as well as the important characterization techniques for assessing the sample properties. We also discuss the key challenges and future directions of the field, including scalable growth, property control, sample stability, and integration with other functional materials.

Graphene/chitosan nanoreactors for ultrafast and precise recovery and catalytic conversion of gold from electronic waste

The extraction of gold (Au) from electronic waste (e-waste) has both environmental impact and inherent value. Improper e-waste disposal poses environmental and health risks, entailing substantial remediation and healthcare costs. Large efforts are applied for the recovery of Au from e-waste using complex processes which include the dissolution of Au, its adsorption in an ionic state and succeeding reduction to metallic Au. These processes themselves being complex and utilizing harsh chemicals contribute to the environmental impact of e-waste. Here, we present an approach for the simultaneous recovery and reduction of Au3+ and Au+ ions from e-waste to produce solid Au0 forms, thus skipping several technological steps. We develop a nanoscale cross-dimensional composite material via self-assembly of two-dimensional graphene oxide and one-dimensional chitosan macromolecules, capable of acting simultaneously as a scavenger of gold ions and as a reducing agent. Such multidimensional architecture doesn't require to apply any voltage for Au adsorption and reduction and solely relies on the chemisorption kinetics of Au ions in the heterogeneous GO/CS nanoconfinements and their chemical reduction on multiple binding sites. The cooperative phenomena in ionic absorption are responsible for the extremely high efficiency of gold extraction. The extraction capacity reaches 16.8 g/g for Au3+ and 6.2 g/g for Au+, which is ten times larger than any existing gold adsorbents can propose. The efficiency is above 99.5 wt.% (current limit is 75 wt.%) and extraction ability is down to very low concentrations of 3 ppm.

Computation of emitter-plasmon interactions using an axis-symmetric model for off-axis dipoles

The axis-symmetric modeling technique is based on expanding vector fields in cylindrical harmonics and computing the response on a two-dimensional cross-section separately for each azimuthal harmonic, significantly reducing computational costs. However, it has limitations when dealing with dipoles placed away from the symmetry axis due to challenges in the expansion of angular modes. To address this, we propose a reformulated axis-symmetric model based on the Fourier expansion of the delta function distribution concerning the azimuthal variable. This model is validated using standard Mie theory for off-axis dipoles and applied to study multiple-emitter-plasmon interactions. The emission properties of a non-cooperative ensemble near a plasmonic nanoparticle are observed to scale with the number of emitters considered, N. Notably, a Dicke effect-like superradiance (N2-dependence) is observed when a spatially disordered ensemble of dipoles oscillates collectively inside a plasmonic dimer gap. This kind of high-level cooperative quantum phenomenon is of high interest in fields such as quantum optics and light-harvesting.

Cooperative Adsorption and Diffusion of Small Alcohols in Metal-Organic Framework ZIF-8 and Intrinsically Microporous Polymer PTMSP.

Fundamental understanding of molecular interactions and transport within microporous materials displaying cooperative Type V adsorption is challenged by the unique features of this isotherm type. In order to capture a broad understanding of this uncommon, yet industrially relevant, behavior in microporous materials, this investigation examines the adsorption equilibria and kinetics of methanol and ethanol in both a metal-organic framework (MOF) material, ZIF-8, and a high free volume polymer of intrinsic microporosity, poly[1-(trimethylsilyl)-1-propyne] (PTMSP). A novel formulation that can capture the cooperative effects of small alcohols in its description of adsorption equilibria and kinetics is proposed. It is subsequently applied to successfully capture some previously uncharacterized or semiempirically characterized data for equilibria and the loading dependence of the diffusivity in both ZIF-8 and PTMSP, which are materials chosen for their industrial relevance. Finally, it is anticipated that the results of this study can fill the current void that exists in meaningful mechanistic and analytical descriptions of cooperative equilibrium and diffusion phenomena in microporous materials.

The regenerative solar system. Unified theory of physics

The Euler’s holomorphic regenerative universe is a quantum-gravitational theory of Earth development recognizing that oxygen, hydrogen, nitrogen and carbon dioxide in the Earth’s hydrosphere engender biological processes along with living organisms able to reshape the planet as surely as any physical force, but with delayed effects, the so-called torsional/gravitational buckling lag. Herein, the environmental sciences as a Vernadsky’s hypothesis precursor to these, become vital for preserving biological recurrent cycles, their nature being artificially changed by a vicious human intervention. The present paper describes the thermal gravitational mechanism of a solar system associated with the regenerative processes of molecular structures (in biology called metabolism or growth) at the quantum-gravitational scale, too slow to be perceived. The term “morph” (or the concept of “morphing” in aeronautics, in mathematics called topological holomorphism) originates from ancient Greeks and refers to the shape, figure, or other related aspects of an evolving entity. Therefore, morphing/morphism pertains to the process of modifying the original form or appearance of a particular object or system. The planets of solar system like “cosmic organisms” can manipulate the curvature and twist of their surfaces to maintain precise control over their recurrent cyclical complex motions (double, orbital and sideral rotations) by the thermal gravitational waves. The out of order function of the thermal gravitational mechanism can lead to the global warming effects associated with both reshaping (earthquakes, fires, floods) surfaces and morphing (as a whole energy metabolism) mutations, crucial for perpetuity of human beings. At the same time, the concept of quantum-gravity light with a topological dual isomorphic structure solves the fundamental problem of a unified theory of physical forces, as kinematic fast dynamo electromagnetic forces for splitting quanta bonded into atomic structures, and persistent (long time) gravitational forces for non-splitting quanta bonded into thermomolecular morphing structures. The only problem remains to gauge such multiple cooperative physical phenomena induced by light, which is solved by diverse reciprocity/equivalence theorems and corresponding conversion factors.

Enhancing cooperativity of molecular J-aggregates by resonantly coupled dielectric metasurfaces

Abstract J-aggregates are supramolecular assemblies of dyes exhibiting strong absorption and fluorescence with narrow linewidths, as well as large optical nonlinearities, induced by the formation of largely delocalized molecular excitons. The degree of cooperativity achievable in J-aggregates ensembles, however, is limited by local disorder and thermally induced decoherence effects. A way to overcome these limitations and increase molecular exciton delocalization and coherence is to couple the ensemble of highly ordered molecular dipoles to a common electromagnetic mode in an optical resonator. In this work, we use dielectric metasurfaces to alter the radiative properties of coupled J-aggregate films and demonstrate a 5-fold Purcell enhancement of the luminesce intensity and narrowing of the emission directivity down to ∼300 mrad around the normal. These results highlight the potential of designer dielectric metasurfaces to foster the emergence of cooperative phenomena in excitonic systems, including optical nonlinearities and superradiance.

Yb-to-Eu Cooperative Sensitization Upconversion in a Multifunctional Molecular Nonanuclear Lanthanide Cluster in Solution.

Lanthanide metal clusters excel in combining molecular and material chemistry properties. Here, we report an efficient cooperative sensitization UC phenomenon of a Eu3+/Yb3+ nonanuclear lanthanide cluster in CD3OD. The synthesis and characterization of the heteronuclear cluster in the solid state and solution are described together with the UC phenomenon showing Eu3+ luminescence in the visible region upon 980 nm NIR excitation of Yb3+ at concentrations as low as 100 nM. Alongside being the Eu/Yb cluster to display UC (with a quantum yield value of 4.88 × 10-8 upon 1.13 W cm-2 excitation at 980 nm), the cluster exhibits downshifted light emission of Yb3+ in the NIR region upon 578 nm visible excitation of Eu3+, which is ascribed to sensitization pathways for Yb through the 5D0 energy levels of Eu3+. Additionally, a faint emission is also observed at ca. 500 nm upon 980 nm excitation, originating from the cooperative luminescence of Yb3+. The [Eu8Yb(BA)16(OH)10]Cl cluster (BA = benzoylacetonate) is also a field-induced single-molecular magnet (SMM) under 4K with a modest Ueff/kB of 8.48 K, thereby joining the coveted list of Yb-SMMs and emerging as a prototype system for next-generation devices, combining luminescence with single-molecular magnetism in a molecular cluster.

Tetrameric self-assembling of water-lean solvents enables carbamate anhydride-based CO2 capture chemistry

Carbon capture, utilization and storage is a key yet cost-intensive technology for the fight against climate change. Single-component water-lean solvents have emerged as promising materials for post-combustion CO2 capture, but little is known regarding their mechanism of action. Here we present a combined experimental and modelling study of single-component water-lean solvents, and we find that CO2 capture is accompanied by the self-assembly of reverse-micelle-like tetrameric clusters in solution. This spontaneous aggregation leads to stepwise cooperative capture phenomena with highly contrasting mechanistic and thermodynamic features. The emergence of well-defined supramolecular architectures displaying a hydrogen-bonded internal core, reminiscent of enzymatic active sites, enables the formation of CO2-containing molecular species such as carbamic acid, carbamic anhydride and alkoxy carbamic anhydrides. This system extends the scope of adducts and mechanisms observed during carbon capture. It opens the way to materials with a higher CO2 storage capacity and provides a means for carbamates to potentially act as initiators for future oligomerization or polymerization of CO2.

Emergent clustering due to quorum sensing interactions in active matter

Many organisms in nature use local interactions to generate global cooperative phenomena. To unravel how the behavior of individuals generates effective interactions within a group, we introduce a simple model, wherein each agent senses the presence of others nearby and changes its physical motion accordingly. This generates non-physical, or virtual interactions between agents. We study the radial distribution function and the cluster size distribution to quantify the emergent interactions for both social and anti-social behavior; We identify social behavior as when an agent exhibits a tendency to remain in the vicinity of other agents, whereas anti-social behavior as when it displays a tendency to escape from the vicinity of others. Using Langevin dynamics simulations in two and three spatial dimensions, we discover that under certain conditions, positive correlations, which indicate attraction can emerge even in the case of anti-social behavior. Our results are potentially useful for designing robotic swimmers that can swim collectively only based on sensing the distance to their neighbors, without measuring any orientational information.

Is Quantization a Co-Operative Phenomenon? On the Ensemble Interpretation of Quantum Physics

A fresh look at Planck's quantum, h, re-interprets action as the companion of power in a dynamic interplay of energies in a multi particle system of the micro world. An exchange of energy, δE, requires a characteristic duration, δτ, with δE and δτ tied together in a natural way. Action, the product δEδτ, must have a nonzero lower limit, h, as a classical necessity everywhere in physics. Zero h would constitute a singularity. The veritable quantum is action, not energy. Black body radiation formulas (Wien, Planck, and Rayleigh) all require this non zero h. Planck's thermodynamic approach was not consistently developed further. Einstein in his 1905 description of the photo effect chose the single "quantum of light" as statistically independent actor in radiation. The resulting discussions about the wave-particle dualism, the meaning of uncertainty, the collapse of wave packets when observed, self-interference, and related problems can be avoided by the consistent view of the ensemble interpretation. In agreement with action defined as δEδτ only co-operative phenomena produce the effects we observe. In particular, this concerns the photon, directly associated with h, as naturally interactive quantum. Careful experiments on low intensity interference suggest to take the photon out of the isolation, thus changing the general view of quantum physics with surprising consequences. Do photons transport energy or action? To understand where 20th century physics has gone a glance at the historical background is in order.

Coherent electronic coupling in quantum dot solids induces cooperative enhancement of nonlinear optoelectronic responses.

Synchronized dynamics of quantum dot (QD) ensembles are essential for generating ultrafast and giant optical responses beyond those of individual QDs. Increasing the strength of the direct electronic coupling between QDs is a key strategy for the realization of cooperative quantum phenomena. Here, we observe a quantum cooperative effect on nonlinear photocurrents caused by the coherent electronic coupling in semiconductor QD solids. We measure quantum interference signals cooperatively generated in QD solids. We control the inter-QD distance with atomic precision using bidentate ligands that strongly link the QDs. The harmonic quantum interference signals are strongly enhanced when shortening the molecular length of the ligand. Furthermore, we clarify that the coherence length of multiexcitons extends to neighbouring QDs. This finding is direct evidence that multiexciton coherent tunnelling assists the ultrafast exciton delocalization. Cooperative enhancement in QD solids may find application in advanced quantum optoelectronics.

Synthesis and Characterization Conducting Polymer Supported CDS-ZNS Nano Composites Used for Various Applications

Keys include undertaking polymer synthesis and physical property research. Conductive is polyaniline. The presence of pristine nano CdS particles in the matrix was demonstrated by X-ray diffraction (XRD).
 In this study, four sol-gel techniques are used to prepare nanostructured polyaniline (PANI). PANI molecular structure was characterized using X-ray diffraction to assess the morphology of PANI samples.
 The results of the prepared PANI's characterization reveal that the unconventional synthesis methods utilized to create it drastically changed its morphology, chemical composition, crystallinity, conductivity, and surface area. The outcomes of the characterization supported this. The manufacturing and properties of polyaniline conducting polymers are examined in this research. The classic and grafted techniques of polyaniline synthesis have been examined. The relationship between structure and properties is established by this high-accuracy development procedure. In the future, polyaniline with altered structure may be employed.
 PANI/CdS nanocomposites have higher DC conductivity than PANI, according to observations.
 In situ production of conducting polyaniline nanocomposites with CdS nanoparticles was achieved by oxidizing aniline with cadmium sulphate at 3.5 pH. Electrical conductivity of polyaniline is influenced by CdS-nanoparticles. In contrast to pure polyaniline, the electrical conductivity of polyaniline nano-composite is increased by the homogenous intercalation of CdS nanoparticles, which results in a cooperative phenomenon between polyaniline and the nanoparticles.

Experimental investigation on the effect of interfacial properties of chemical flooding for enhanced heavy oil recovery

Chemical compound flooding has demonstrated its efficacy in enhancing light oil recovery through ultra-low interfacial tension (IFT). However, the optimization of chemical systems properties for displacing heavy oil has not been clarified. This research aims to address this problem by designing common polymer and three surfactant-polymer (SP) systems with varying IFT and interfacial viscoelasticity behaviors, and comparing their ability to recover heavy oil. The findings of core flooding tests indicate that the system with low IFT and high interfacial viscoelasticity simultaneously has a better displacement efficiency for heavy oil than other flood systems, which could enhance heavy oil recovery by 21.94%. Micro-model tests reveal the underlying mechanisms driving the enhanced macro-scale oil recovery. The emulsion formation and interface expansion facilitated by low IFT, as well as increased emulsion stability and reduced snap-off of oil droplets due to the presence of an elastic oil-water interfacial film. These phenomena is more capable of driving microscopic heterogeneous remaining oil and film remaining oil than other solution. The comparative experiment analysis shows that the difference in chemical flooding between heavy oil and light oil is caused by the discrepant distributions of surfactants at the oil-water interface. The light oil interface is a monolayer surfactant molecular film, the heavy components and surfactant moleculars exhibit both competitive and cooperative adsorption phenomena at the oil-water interface. The occurrence of viscosity reduction and increased emulsion stability are more influential factors in the process of heavy oil displacement than those of conventional ultra-low IFT systems used for light oil recovery.

Prediction of microstructure evolution at the atomic scale by deep generative model in combination with recurrent neural networks

A novel method to predict multi-atom cooperative phenomena at atomic scale is proposed based on a deep generative model in combination with recurrent neural network. The variational autoencoder (VAE) model successfully identifies three different crystal orientations in the polycrystalline nickel by using 10-dimensional latent variables and restores the image of atomic configurations reflecting the crystal orientation of each grain. Moreover, microstructure evolution of the polycrystalline iron is successfully predicted through three steps: dimensionality reduction of atomic coordinates from the MD simulation using the encoder, time evolution of latent variables using the long short-term memory (LSTM) model, and data restoration using the decoder. We successfully predict the microstructure that cannot be reproduced on the time scale of MD simulations by decoding latent variables in the future time from the LSTM model. This is a new attempt of acceleration of the MD simulation that differs significantly from conventional acceleration methods.

Highly Cooperative CO2 Adsorption via a Cation Crowding Mechanism on a Cesium-Exchanged Phillipsite Zeolite.

An understanding of the CO2 adsorption mechanisms on small-pore zeolites is of practical importance in the development of more efficient adsorbents for the separation of CO2 from N2 or CH4 . Here we report that the CO2 isotherms at 25-75 °C on cesium-exchanged phillipsite zeolite with a Si/Al ratio of 2.5 (Cs-PHI-2.5) are characterized by a rectilinear step shape: limited uptake at low CO2 pressure (PCO2 ) is followed by highly cooperative uptake at a critical pressure, above which adsorption rapidly approaches capacity (2.0 mmol g-1 ). Structural analysis reveals that this isotherm behavior is attributed to the high concentration and large size of Cs+ ions in dehydrated Cs-PHI-2.5. This results in Cs+ cation crowding and subsequent dispersal at a critical loading of CO2 , which allows the PHI framework to relax to its wide pore form and enables its pores to fill with CO2 over a very narrow range of PCO2 . Such a highly cooperative phenomenon has not been observed for other zeolites.

Highly Cooperative CO2 Adsorption via a Cation Crowding Mechanism on a Cesium‐Exchanged Phillipsite Zeolite

AbstractAn understanding of the CO2 adsorption mechanisms on small‐pore zeolites is of practical importance in the development of more efficient adsorbents for the separation of CO2 from N2 or CH4. Here we report that the CO2 isotherms at 25–75 °C on cesium‐exchanged phillipsite zeolite with a Si/Al ratio of 2.5 (Cs‐PHI‐2.5) are characterized by a rectilinear step shape: limited uptake at low CO2 pressure (PCO2) is followed by highly cooperative uptake at a critical pressure, above which adsorption rapidly approaches capacity (2.0 mmol g−1). Structural analysis reveals that this isotherm behavior is attributed to the high concentration and large size of Cs+ ions in dehydrated Cs‐PHI‐2.5. This results in Cs+ cation crowding and subsequent dispersal at a critical loading of CO2, which allows the PHI framework to relax to its wide pore form and enables its pores to fill with CO2 over a very narrow range of PCO2. Such a highly cooperative phenomenon has not been observed for other zeolites.

Ferroelectric properties of triglycine sulfate crystals doped with glycine analogs

Single crystals of ferroelectric triglycine sulfate doped with glycine analogs serine, threonine, lactic acid, and alaninol were grown via the slow solvent evaporation method. The resulting ferroelectric domain structures and polarization–electric field hysteresis loops revealed that these dopants caused triglycine sulfate to form a multidomain structure. This was attributed to hydrogen bonds not being formed, which is significant in polarization reversal, due to the side chains and the substituents of the dopant molecules. Therefore, the dopants did not affect the surrounding dipoles enough to cause cooperative phenomena, such as dipole‒dipole interactions, and do not result in the formation of a single- domain, unlike alanine in our previous study.

Microscopic Hamiltonian and chaotic behavior for Barium Titanate nanoparticles revealed by photonic tunneling model

In order to understand the microscopic properties of the ferroelectric nanoparticles, we review concepts of the attractive BaTiO3 crystals where a photon field from its constituent electrons and ions are considered. We present an associated Hamiltonian and extended potential which are the bases of the physical description of the system from certain geometry of the semiquantal space with the specific phonon mode. Furthermore, we formulate the nonlinear dynamics equation of the systems with the famous microscopic Hamiltonian and Heisenberg equation of motion. In addition, we interest ourselves to a system of BaTiO3 crystals and hypothesis leading to order-disorder nature of phase transitions. The latter are linked to the cooperative phenomenon of chains. The numerical simulations reveal that complex behaviors propagate in such system that can be useful for future application of Barium Titanate crystals in modern electronic technologies.

Low-Gradient Magnetophoresis of Nanospheres and Nanorods through a Single Layer of Paper.

The possible magnetophoretic migration of iron oxide nanoparticles through the cellulosic matrix within a single layer of paper is challenging with its underlying mechanism remained unclear. Even with the recent advancements of theoretical understanding on magnetophoresis, mainly driven by cooperative and hydrodynamics phenomena, the contributions of these two mechanisms on possible penetration of magnetic nanoparticles through cellulosic matrix of paper have yet been proven. Here, by using iron oxide nanoparticles (IONPs), both nanospheres and nanorods, we have investigated the migration kinetics of these nanoparticles through grade 4 Whatman filter paper with a particle retention of 20-25 μm. By performing droplet tracking experiments, the real-time stained area growth of the particle droplet on the filter paper, under the influences of a grade N40 NdFeB magnet, were recorded. Our results show that the spatial and temporal expansion of the IONP stain is biased toward the magnet and such an effect is dependent on (i) particle concentration and (ii) particle shape. The kinetics data were first analyzed by treating it as a radial wicking fluid, and later the IONP distribution within the cellulosic matrix was investigated by optical microscopy. The macroscopic flow front velocities of the stained area ranged from 259 μm/s to 16 040 μm/s. Moreover, the microscopic magnetophoretic velocity of nanorod cluster was also successfully measured as ∼214 μm/s. Findings in this work have indirectly revealed the strong influence of cooperative magnetophoresis and the engineering feasibility of paper-based magnetophoretic technology by taking advantage of magnetoshape anisotropy effect of the particles.

Nonequilibrium dynamics of the Ising model on heterogeneous networks with an arbitrary distribution of threshold noise.

The Ising model on networks plays a fundamental role as a testing ground for understanding cooperative phenomena in complex systems. Here we solve the synchronous dynamics of the Ising model on random graphs with an arbitrary degree distribution in the high-connectivity limit. Depending on the distribution of the threshold noise that governs the microscopic dynamics, the model evolves to nonequilibrium stationary states. We obtain an exact dynamical equation for the distribution of local magnetizations, from which we find the critical line that separates the paramagnetic from the ferromagnetic phase. For random graphs with a negative binomial degree distribution, we demonstrate that the stationary critical behavior as well as the long-time critical dynamics of the first two moments of the local magnetizations depend on the distribution of the threshold noise. In particular, for an algebraic threshold noise, these critical properties are determined by the power-law tails of the distribution of thresholds. We further show that the relaxation time of the average magnetization inside each phase exhibits the standard mean-field critical scaling. The values of all critical exponents considered here are independent of the variance of the negative binomial degree distribution. Our work highlights the importance of certain details of the microscopic dynamics for the critical behavior of nonequilibrium spin systems.