Asymmetric Aggregation Research Articles

The Feasibility of Coordinating International Monetary Policy Strategies in the Context of Asymmetric Demand Shocks

In the context of the increasing interdependence of countries due to the development of international trade, a relevant question arises as to whether it is necessary to conduct independent monetary policies for each country or whether it is advisable to coordinate these policies. This question becomes a key in the debate on optimal monetary policy strategies in open economies. The aim of this study is to analyze the impact of asymmetric aggregate demand shocks on the appropriateness of monetary policy coordination in a simple stochastic model of two interacting countries. The analysis of equilibrium states of the monetary authorities’ interaction strategies under study was carried out analytically by minimizing the loss function and solving one-period static optimization problems. The equilibrium states of macroeconomics of interacting countries under coordination of monetary policy and in cases of lack of coordination (Nash and Stackelberg equilibrium) in the presence of asymmetric, serially uncorrelated demand shocks have been analyzed. It is proven that the response of inflation to asymmetric demand shocks is smaller in the case of coordinated policy than in the case of non-cooperative policy. The loss function analysis shows that the compensation of demand shocks is found to be more costly in Nash equilibrium than in the case of monetary authority coordination policy. The analysis of the monetary authorities’ interaction strategies showed that the real exchange rate plays an important role in balancing supply and demand in the two economies.

Novel Asymmetric Aggregation Strategy to Boost Charge Separation in Carbon Nitride Polymers for High-Performance Hydrogen Photosynthesis

Novel Asymmetric Aggregation Strategy to Boost Charge Separation in Carbon Nitride Polymers for High-Performance Hydrogen Photosynthesis

Asymmetric aggregation enables red-light CO2 reduction with tunable activity and selectivity by intermolecular electronic coupling

Photocatalytic CO2 reduction to value-added chemicals is a promising way to simultaneously mitigate environmental and energy issues. Integrating low-energy red light harvesting, fast charge separation, and robust CO2 activation in a photosystem is a crucial prerequisite for highly efficient CO2 photoreduction but remains a huge challenge. Herein, we constructed an aggregated [Ru(2, 2'-bipyridine)3]Cl2 (denoted as Ru(bpy)3Cl2) photosystem. Various characterizations combining molecular dynamic simulations and theoretical calculations confirm that the electronic coupling between adjacent Ru(bpy)3Cl2 molecules can induce orbital hybridization, thus broadening the light absorption edge to the red light region. Meanwhile, the asymmetric aggregation of Ru(bpy)3Cl2 enables exciton dissociation and charge transfer through a dipole polarization effect. Significantly, this dipole polarization can also upshift the d-orbital of Ni catalytic centers, greatly strengthening the activation of CO2 and lowering the formation energy barrier of COOH* intermediates. Consequently, the apparent quantum yield (AQY) of aggregates for CO2-to-CO reduction reaches 4.2% at 610 nm, significantly higher than the AQYs of other reported photosystems at wavelengths ≥ 600 nm. More importantly, the catalytic efficiency and selectivity of CO2 reduction can be rationally tuned by controlling the aggregated degrees of Ru(bpy)3Cl2. This work highlights the key role of Ru(bpy)3Cl2 aggregation in prompting red-light harvesting and CO2 activation, which may help boost CO2 photoreduction efficiency from a fresh perspective.

Controlled asymmetric aggregation advances n → π* electronic transition and charge separation for enhanced photocatalytic hydrogen synthesis

Photocatalytic water splitting into hydrogen is considered as a promising approach for solar energy storage. The existing organic semiconductor photocatalysts are mainly dominated by π-conjugated covalent structures featuring π → π* electronic transition. Recent studies found that activating n → π* electronic transition is an effective strategy for improving photocatalytic activity of organic semiconductors. Nevertheless, n → π* electronic transition is generally forbidden in perfect symmetric structures. Herein, we have successfully synthesized asymmetric trithiocyanuric acid (TA) aggregates by a solvent chemistry strategy. The asymmetric degrees of TA aggregates can be greatly tuned by changing the pulling strength of solvent molecules. The asymmetric characteristic of TA aggregates increases the orbital overlap between the lone pair electrons on sulfur atoms and the adjacent π* orbitals of triazine, thus allowing n → π* electronic transition. Simultaneously, the asymmetric aggregation induces a large dipole moment, significantly improving the separation and transfer of charge carriers. After an assay of a hydrogen evolution reaction, a quantum yield of 42.9 % at 400 nm was recorded for the asymmetric TA aggregates, which is much higher than those of most existing covalent semiconductors. This study unlocks a fresh realm of artificial photosynthesis, which uses asymmetric aggregates featuring n → π* electronic transition for efficient photocatalytic hydrogen production.

Asymmetric Aggregation Network for Accurate Ship Detection in Optical Imagery

Asymmetric Aggregation Network for Accurate Ship Detection in Optical Imagery

Realized semi variance quantile connectedness between oil prices and stock market: Spillover from Russian-Ukraine clash

This study aims to investigate the dynamic relationship between oil prices and stock markets in the G5+ countries using Parkinson's proximal realized volatility. We separate positive and negative semi-variance to compute asymmetric aggregate static spillovers according to the Diebold and Yilmaz (DY) approach. Moreover, we use a Quantile VAR to investigate the behavior of series in different quantiles corresponding to different market scenarios. Consistently with the literature concerns, we use a daily sample of market indices prices with the Brent oil price from June 1, 2017, to July 2, 2022. We found an asymmetric linkage between oil prices and the stock market, which has significant implications for portfolio hedging strategies. Specifically, our research indicates that the impact of the Russian-Ukrainian conflict on the energy crisis has been significantly higher than that of the COVID-19 pandemic, especially in the short term. However, we observe a higher persistence of negative spillovers for COVID-19 compared to those recorded during the Russia-Ukraine war. From a methodological viewpoint, this result enforces the choice of an asymmetric model to investigate the volatility transmission between financial market series. Finally, we found crude oil to emit volatility spillovers in quantiles above 80%. This result emphasizes the instability perceived in crude oil price when general market volatility increase. Quite the opposite, about one-third of oil price shocks, are linked to the national stock exchange uncertainty in low and middle quantiles, underlining the investors' dependency on this commodity. These results have important implications for policymakers and institutional authorities, who must consider the changing macroeconomic environment and reduce dependence on Russian energy.

Nonreciprocal transparency in asymmetric gyrotropic trimers

We demonstrate theoretically an extreme scattering nonreciprocity, namely nonreciprocal transparency, in an asymmetric aggregate of deep-subwavelength gyrotropic trimer rods. By examining the asymmetric characteristics indicated in the differential extinction efficiency spectra, we explicitly reveal the underlying mechanism of such pronounced scattering nonreciprocity, arising from the asymmetrical magnetoelectric cross interactions besides the simultaneous excitations of the rotating magnetic dipole and electric dipole at each rod. Further, both far-field and near-field distributions are also investigated to validate our finding through full-wave numerical simulations. It may shed new light on the field of optics and photonics related to the nonreciprocal scattering on particle clusters.

Effects of gradient distribution and aggregate structure of fibers on the flexibility and flexural toughness of natural moso bamboo (Phyllostachys edulis)

Bamboo is a unidirectional fiber-reinforced material with excellent flexibility and flexural toughness arising from its unique cellular hierarchical structure, which creates an urgent demand in the bamboo industry to understand potential mechanisms of those two performances. In this study, a proposed original method was used to quantitatively evaluate the gradient distribution and aggregate structure of fibers on the flexibility and flexural toughness of natural moso (Phyllostachys edulis) bamboo, with a comparison to two other natural wood. Results showed that gradient distribution of fibers across the bamboo culm is the key to bamboo's varying flexibility along the diameter at the tissue level, whereas the asymmetric aggregate structure (vascular bundles) of fibers causes a difference in the flexibility when under different bending directions. Bamboo had possessed high strength and high toughness, but a conflict between the flexibility and flexural toughness existed. Compared to natural wood species of similar density, the flexibility and flexural toughness of bamboo was ∼1.8 and 1.42–4.96 times greater that of wood, respectively. At the cell level, the combination of high-performance hard fibers and soft foamy parenchyma cells act upon the bamboo's flexibility, while the excellent flexural toughness stemmed from the fiber bridging and pull-out caused by high performance and aspect ratio, low microfibrils angle of fibers, and crack deflection along the longitudinal/radial direction. These findings helped contribute critical knowledge surrounding the flexibility and flexural toughness of bamboo, especially for optimizing the process of bamboo-based winding composites pipes (BWCPs).

Supramolecular chirality of multicomponent self-assembled systems and their applications

<p indent=0mm>Chirality is closely associated with life, such as amino acids at the molecular level, secondary structures of proteins (DNA, RNA), nanoscale helices and macroscopic conches. Due to the dynamic property of non-covalent bond, self-assembly of molecule shows environmental adaptability. The stacking form of molecule can be regulated via tunning non-covalent interaction. The asymmetric aggregation of molecular building blocks is called supramolecular chirality which is not only related to the structure of molecule and molecular chirality, but also influenced by non-covalent interaction. Regulation of the emergence, amplification, transfer and inversion of supramolecular chirality is an important field. The assemblies with supramolecular chirality are usually driven by various non-covalent interactions with unique chiral micro-environment. Design and fabrication of supramolecular assemblies with two or more kinds of components are much more complex than the single component systems due to the complexity of possible pathways. Compared with single-component systems which have already matured, both basic and application research of multi-component supramolecular chiral assemblies are still limited. However, the study of supramolecular chirality of multicomponent self-assembled systems not only benefit to simulate complex biological systems, but also contribute to the deep understanding of the origin of homochirality in nature to further apply in bionics, which is of great significance. Therefore, in this review article, we mainly discuss the construction of multicomponent self-assembled systems including solvent effect, hydrogen bond, structural analogues, organic/inorganic co-assembly. Solvent polarity has a great influence on self-assembled process of molecules especially for amphiphiles whose molecular stacking layer that exposes to solvents should be solvophilic. Besides the effect of polarity, solvent molecules also could act as an active component to participate self-assembled process generating significant influence on self-assembly behavior and even supramolecular chirality. Due to the directionality and relatively strong intensity compared with other non-covalent interactions, hydrogen bonding has been considered as the important interaction to construct supramolecular assemblies. Hydrogen bonding could be widely observed among amide/imide, ureido and carboxylic acid groups which has been introduced in this review in detail. And the influence of hydrogen bond to supramolecular chirality also has been fully discussed. Introducing structural analogues into building block with chiral center is another effective method to construct multicomponent supramolecular assemblies. Two different paths upon the aggregation of structural analogues including self-sorting and coassembly might occur which are controlled via equilibrium of kinetically or thermodynamically. The realization of coassembly between structural analogues requires strong interactions between components or similarly staking mode. Because of the excellent properties of inorganic material especially in luminescence, inorganic/organic coassembled materials which could be applied in chiroptical with tunable chiral and optical properties have emerged. Moreover, a serial of three component supramolecular assemblies with tunable chiral and optical properties based on the research of double components have been developed. Strong non-covalent interactions including hydrogen bond and π-π stacking interaction are benefit for forming multicomponent supramolecular chiral assemblies. Besides design and fabrication multicomponent supramolecular chiral assemblies, we also introduced their applications in chiral recognition, circularly polarized luminescence (CPL), chiral catalysis and chiral template. Chiral recognition not only displays the interaction between achiral molecules with various chiral molecules, but also between supramolecular assemblies with chiral molecules. We mainly discussed the recognition of supramolecular assemblies to enantiomers. CPL is a nonnegligible application field of multicomponent supramolecular chiral assemblies which has attracted increasing attention due to its wide potential applications in optical displays, encryption and storage of information, photoelectric devices, chiroptical materials, and so on. Catalysts for asymmetric reactions under mild conditions have been widely studied based on different supramolecular assemblies including helical nanorods, nanotubes and vesicles. We expect this review will serve as an introduction and reference for researchers who are interested in exploring this field.

Combining Multiple Biometric Traits Using Asymmetric Aggregation Operators for Improved Person Recognition

Biometrics is a scientific technology to recognize a person using their physical, behavior or chemical attributes. Biometrics is nowadays widely being used in several daily applications ranging from smart device user authentication to border crossing. A system that uses a single source of biometric information (e.g., single fingerprint) to recognize people is known as unimodal or unibiometrics system. Whereas, the system that consolidates data from multiple biometric sources of information (e.g., face and fingerprint) is called multimodal or multibiometrics system. Multibiometrics systems can alleviate the error rates and some inherent weaknesses of unibiometrics systems. Therefore, we present, in this study, a novel score level fusion-based scheme for multibiometric user recognition system. The proposed framework is hinged on Asymmetric Aggregation Operators (Asym-AOs). In particular, Asym-AOs are estimated via the generator functions of triangular norms (t-norms). The extensive set of experiments using seven publicly available benchmark databases, namely, National Institute of Standards and Technology (NIST)-Face, NIST-Multimodal, IIT Delhi Palmprint V1, IIT Delhi Ear, Hong Kong PolyU Contactless Hand Dorsal Images, Mobile Biometry (MOBIO) face, and Visible light mobile Ocular Biometric (VISOB) iPhone Day Light Ocular Mobile databases have been reported to show efficacy of the proposed scheme. The experimental results demonstrate that Asym-AOs based score fusion schemes not only are able to increase authentication rates compared to existing score level fusion methods (e.g., min, max, t-norms, symmetric-sum) but also is computationally fast.

Cone-in-cone and beef mineralization associated with Triassic growth basin faulting and shallow shale diagenesis, Edgeøya, Svalbard

AbstractCone-in-cone (CIC) and beef (BF) carbonate lenses ornament detachment zone faults underlying Triassic growth basins on Edgeøya. Field relationships place CIC and BF growth as during early diagenesis and a transition from hydroplastic to a later brittle-style of faulting that is marked by coarser calcite veining. Deformation is constrained to have occurred at &lt;300 m depth. Multiple models exist for CIC formation. For the Edgeøya example, textural analysis of thin-sections suggests that small tensile fractures and carbonate shell fragments nucleated development of calcite aggregates with CIC and BF morphology within unconsolidated to poorly consolidated sediment to form asymmetric antitaxial tensile aggregates subparallel to bedding and fault surfaces. The conical forms result from differential growth on stepped, cleavage-parallel faces of fibres facing host sediment, with preferential inclusion incorporation at inner corners. The preferred directions of calcite growth are attributed to local stresses and seepage flow associated with pore pressure gradients. Substantial framboidal pyrite in the sediments represents an early phase of microbially driven sulphate reduction, which may have induced calcite mineralization. The transition to brittle-style faulting was marked by development of deformation twins in CIC/BF fibres, and a transition to coarse, blocky calcite growth in relay arrays of steeply oriented microveins. This indicates local fault-related stresses substantially changed during shallow diagenesis and lithification, an evolution attributed to changing pore pressures, seepage forces and material moduli. Calcite mineralizations at Edgeøya track the very significant changes in mechanical properties and stress states that occur during synlithification deformation at very shallow crustal levels.

Supramolecular Chirality Based on Calixarenes

Supramolecular chirality has an exciting potential in mimetic enzyme, asymmetric catalyst, separation and analysis of enantiomers, explanation of chiral origin, information recording and reading, functional nanomaterials, and so on. With calixarenes as building blocks, supramolecular chirality with various topologies such as propeller type, single helix, double helices, triple helices and quintuple helices, helical nanotubes, β-sheets, chiral cavity and capsule, (10,3)-a net topology, chiral Kagome lattice, chiral metal nanomaterials, as well as many other asymmetric aggregates existing in solution, solid state and even on two dimensional surface can be realized. This review describes the research works about supramolecular chirality based on calixarenes. Keywords: Calixarenes, supramolecular chirality, self-assembly, asymmetric catalyst, propeller type, quintuple helices, β-sheets, chiral Kagome lattice, chiral metal nanomaterials, hydrophobic cavity, mimetic enzyme, helical nanofibers, nonlinear optical (NLO), stoichiometry

Correlated nucleation model for simulating nanocluster pattern formation on Si(111)7 × 7 surface

We study the aggregation mechanisms of metal nanoclusters on the Si(111)7 × 7 reconstructed surface using a correlated nucleation model, in which the nucleation and growth behavior of a cluster (irreversible or partially reversible growth) depend on the local environment of the cluster. The kinetic Monte Carlo simulation of the model shows that with increasing temperature, the correlated nucleation effect causes a transition of growth behavior from asymmetric adatom aggregation between faulted and unfaulted half cells with a strong preference of occupation of faulted half cells, to compact cluster aggregation with a low occupation preference at high temperatures. As a result the preference as a function of the temperature exhibits a nonmonotonous behavior, with a maximum located at the temperature at which the transition of growth behavior has been observed. Both the simulated cluster morphologies and the quantitative analysis of the cluster distribution are in good agreement with the results observed from relevant growth experiments.

Bending of nanoscale filament assemblies by elastocapillary densification

We report a mechanism by which nanoscale filaments self-assemble into asymmetric aggregates by elastocapillary action. Specifically, capillary rise of liquid into an asymmetric pattern of vertically aligned filaments causes the filaments to deflect laterally during elastocapillary densification. We quantitatively show that the lateral deflection can be controlled precisely by the pattern shape and the coupling strength among the filaments. We exploit this mechanism to fabricate asymmetric micropillars and multidirectional bridges of densely packed carbon nanotubes. Analogous behavior occurs as biological filaments interact with liquids, and these findings enable scalable fabrication of anisotropic filament assemblies for manipulating surface interactions between solids and liquids.

Simulation study of asymmetric aggregation behavior of adatoms on Si(1 1 1)7×7

We perform detailed simulations of the nucleation and growth of adatoms on the Si(1 1 1)7×7 reconstructed surface based on a modified cooperative diffusion model, and analyze the effect of different asymmetric diffusion and aggregation mechanisms on the growth behavior. We demonstrate that the asymmetry controlled by the difference of effective binding energies between faulted and unfaulted half cells has a strong influence on the preference of occupation of faulted half cells at higher temperatures for both irreversible and partially reversible aggregation. Using the occupation preference as a measure of cluster ordering, the simulation clearly shows growth mode transition from random nucleation at low temperatures to ordered self-organized growth at high temperatures in the case of partially reversible aggregation.

Aggregation of asymmetric distances in Computer Science

In this paper we provide a general description of how to combine a collection (not necessarily finite) of asymmetric distances in order to obtain a single one as output. To this end we introduce the notion of asymmetric distance aggregation function that generalizes the well-known one for distance spaces given by Borsik and Doboš [J. Borsik, J. Doboš, On a product of metricspaces, Math. Slovaca 31 (1981) 193–205]. Among other results, a characterization of such functions is obtained in terms of monotony and subadditivity. Finally, we relate our results to Computer Science. In particular we show that the mathematical formalism based on complexity distances, which has been introduced by Romaguera and Schellekens [S. Romaguera, M. Schellekens, Quasi-metric properties of complexity spaces, Topol. Appl. 98 (1999) 311–322] for the complexity analysis of programs and algorithms, can be obtained as a particular case of our new framework using appropriate asymmetric aggregation distance functions.

An Organozinc Hydrazide-Thiolate Aggregate with a Zn3N4S2 Core

The first organometallic zinc hydrazide-thiolate cluster, [(MeZn)2(PhSZn)(HNNMe2)(H2N-NMe2)(SPh)2]2 (1) has been prepared by alkane elimination from dimethylzinc solutions upon treatment with N,N-dimethylhydrazine and thiophenol and characterised by NMR spectroscopy, elemental analysis and single crystal X-ray diffraction. Compound 1 forms asymmetric aggregates containing a Zn3N4S2 core. The core features rings with different connectivities. A seven-membered ZnSZnNNZnS ring comprises three fivemembered rings, two of a ZnSZnNN and one of a ZnNZnNN atom sequence. Intermolecular S···H bonding is observed in the crystal.

Adsorption of CTAB on Hydrophilic Silica Studied by Linear and Nonlinear Optical Spectroscopy

Vibrational sum-frequency spectroscopy (SFS) and total internal reflection Raman scattering (TIR Raman) have been used to study the adsorption of hexadecyltrimethylammonium bromide (CTAB) to hydrophilic silica. These two complementary techniques permit the determination of the adsorbed amount with a sensitivity of approximately 1% of the maximum surface coverage, changes in the average tilt of the adsorbed molecules, the presence of asymmetric aggregates in the adsorbed film, and the structure and orientation of the water molecules in the interfacial region. The TIR Raman spectra show a monotonic increase with CTAB concentration with no measurable changes in the relative intensities of the different polarization combinations probed, implying that no significant changes occur in the conformational order of the hydrocarbon chain. In the sum-frequency (SF) spectra, no detectable peaks from the surfactant headgroup and hydrophobic chain were observed at any surface coverage. Major changes are observed in the water bands of the SF spectra, as the originally negatively charged silica surface becomes positively charged with an increase in the adsorbed amount, inducing a change in the polar orientation of the water molecules near the surface. The detection limits for hydrocarbons chains in the SF spectra were estimated by comparison with the SF spectrum of a disordered octadecyltrichlorosilane monolayer. The simulations demonstrate that the asymmetry in the adsorbed CTAB layer at any concentration is less than 5% of a monolayer. The results obtained pose severe constraints on the possible structural models, in particular at concentrations below the critical micellar concentration where information is scarce. The formation of hemimicelles, monolayers and other asymmetric aggregates is ruled out, with centrosymmetric aggregates forming from early on in the adsorption process.

Zinc Hydrazides and Hydrazide‐Alkoxides with Cyclic and Acyclic Hydrazide Substituents

AbstractThe tetrameric organometallic zinc hydrazides the {(RZn)4[NHN(CH2)n]4} (R = Me, Et, iPr and n = 5, 4) (1–6), were prepared by alkane elimination from dialkyl zinc solutions and the ring‐substituted hydrazine derivatives 1‐aminopiperidine and 1‐aminopyrrolidine at ambient temperature. They were characterized by NMR (1H, 13C) and IR spectroscopy, by mass spectrometry and by elemental analyses. The compounds form asymmetric aggregates, containing Zn4N8 cores. Zinc trisalkoxide‐monohydrazides can be prepared in one‐pot syntheses by reacting dialkylzinc solutions simultaneously with alcohols and hydrazines. Reactions of dimethylzinc with isopropanol and monomethylhydrazine or mono‐t‐butylhydrazine in 2:1:1.03 ratio resulted in the formation of [(MeZn)4(NHNHR)(OiPr)3] [R = Me (7), tBu (8)]. In a similar fashion, dialkylzinc compounds react with 1‐aminopiperidine and alcohol in 5:4:4 ratio to give {(RZn)4[NHN(CH2)5](OR′)3]} [R = Me, R′ = iPr (9); R = Et, R′ = Et (10), iPr (11)]. These compounds were characterized as the above compounds. The structures of compounds 8 and 9 were also determined by crystal structure analyses. These compounds show an unsymmetrical aggregation with a Zn4N2O3 cage structure, confirmed by spectroscopic methods in solution.

Bucky ball functions in Balbiani body assembly and animal–vegetal polarity in the oocyte and follicle cell layer in zebrafish

The Balbiani body is an evolutionarily conserved asymmetric aggregate of organelles that is present in early oocytes of all animals examined, including humans. Although first identified more than 150 years ago, genes acting in the assembly of the Balbiani body have not been identified in a vertebrate. Here we show that the bucky ball gene in the zebrafish is required to assemble this universal aggregate of organelles. In the absence of bucky ball the Balbiani body fails to form, and vegetal mRNAs are not localized in oocytes. In contrast, animal pole localized oocyte markers are expanded into vegetal regions in bucky ball mutants, but patterning within the expanded animal pole remains intact. Interestingly, in bucky ball mutants an excessive number of cells within the somatic follicle cell layer surrounding the oocyte develop as micropylar cells, an animal pole specific cell fate. The single micropyle permits sperm to fertilize the egg in zebrafish. In bucky ball mutants, excess micropyles cause polyspermy. Thus bucky ball provides the first genetic access to Balbiani body formation in a vertebrate. We demonstrate that bucky ball functions during early oogenesis to regulate polarity of the oocyte, future egg and embryo. Finally, the expansion of animal identity in oocytes and somatic follicle cells suggests that somatic cell fate and oocyte polarity are interdependent.