Heterogeneous Coupling Research Articles

Highly efficient heterogeneous copper-catalysed coupling of oxime acetates with isothiocyanates leading to 2-aminothiazoles_ESI

Highly efficient heterogeneous copper-catalysed coupling of oxime acetates with isothiocyanates leading to 2-aminothiazoles_ESI

Eosin Y dye-based porous organic polymers for highly efficient heterogeneous photocatalytic dehydrogenative coupling reaction

Eosin Y dye has been successfully embedded into a nanoporous networkEY-POPsthrough a bottom-up strategy. The polymers could be used as highly effective and reusable heterogeneous organo-photocatalyst for the dehydrogenative coupling reaction.

Dynamics of phase oscillators with generalized frequency-weighted coupling.

Heterogeneous coupling patterns among interacting elements are ubiquitous in real systems ranging from physics, chemistry to biology communities, which have attracted much attention during recent years. In this paper, we extend the Kuramoto model by considering a particular heterogeneous coupling scheme in an ensemble of phase oscillators, where each oscillator pair interacts with different coupling strength that is weighted by a general function of the natural frequency. The Kuramoto theory for the transition to synchronization can be explicitly generalized, such as the expression for the critical coupling strength. Also, a self-consistency approach is developed to predict the stationary states in the thermodynamic limit. Moreover, Landau damping effects are further revealed by means of linear stability analysis and resonance poles theory below the critical threshold, which turns to be far more generic. Our theoretical analysis and numerical results are consistent with each other, which can help us understand the synchronization transition in general networks with heterogenous couplings.

Active tectonics of Peru: Heterogeneous interseismic coupling along the Nazca megathrust, rigid motion of the Peruvian Sliver, and Subandean shortening accommodation

AbstractOver 100 GPS sites measured in 2008–2013 in Peru provide new insights into the present‐day crustal deformation of the 2200 km long Peruvian margin. This margin is squeezed between the eastward subduction of the oceanic Nazca Plate at the South America trench axis and the westward continental subduction of the South American Plate beneath the Eastern Cordillera and Subandean orogenic wedge. Continental active faults and GPS data reveal the rigid motion of a Peruvian Forearc Sliver that extends from the oceanic trench axis to the Western‐Eastern Cordilleras boundary and moves southeastward at 4–5 mm/yr relative to a stable South America reference frame. GPS data indicate that the Subandean shortening increases southward by 2 to 4 mm/yr. In a Peruvian Sliver reference frame, the residual GPS data indicate that the interseismic coupling along the Nazca megathrust is highly heterogeneous. Coupling in northern Peru is shallow and coincides with the site of previous moderate‐sized and shallow tsunami‐earthquakes. Deep coupling occurs in central and southern Peru, where repeated large and great megathrust earthquakes have occurred. The strong correlation between highly coupled areas and large ruptures suggests that seismic asperities are persistent features of the megathrust. Creeping segments appear at the extremities of great ruptures and where oceanic fracture zones and ridges enter the subduction zone, suggesting that these subducting structures play a major role in the seismic segmentation of the Peruvian margin. In central Peru, we estimate a recurrence time of 305 ± 40 years to reproduce the great 1746Mw~8.8 Lima‐Callao earthquake.

Synchronization Regime of Star-Type Laser Network With Heterogeneous Coupling Delays

The synchronization properties and the sensitivity of generalized lag synchronization (GLS) in all-optical star network with mutually coupled semiconductor laser in the presence of heterogeneous delays are investigated numerically. The hub node and the side nodes are optically coupled with asymmetrical injection strength. The dependence of GLS on the effects of lasers’ pump current, injection strength, asymmetrical injection factor, and frequency detuning distribution is examined. It is found that, except for the injection strength and frequency detuning, the pump current of hub laser and the asymmetrical injection factor are also key factors that determine the quality of GLS in star network with heterogeneous delays. Extremely asymmetrical injection as well as large pump current of hub laser is suggested to obtain high-quality GLS in wide parameter regions. Such GLS can also be obtained in a large-scale laser network with heterogeneous coupling delays, and is hardly affected by the time delay distribution, which opens possibilities for multi-user chaotic communication and synchronization-based secure key distribution network among the side nodes.

Optimization of noise-induced synchronization of oscillator networks.

We investigate common-noise-induced synchronization between two identical networks of coupled phase oscillators exhibiting fully locked collective oscillations. Using the collective phase description method for fully locked oscillators, we demonstrate that two noninteracting networks of coupled phase oscillators can exhibit in-phase synchronization between the networks when driven by weak common noise. We derive the Lyapunov exponent characterizing the relaxation time for synchronization and develop a method of obtaining the optimal input pattern of common noise to achieve fast synchronization. We illustrate the theory using three representative networks with heterogeneous, global, and local coupling. The theoretical results are validated by direct numerical simulations.

ChemInform Abstract: A Highly Efficient Heterogeneous Copper‐Catalyzed Chan‐Lam Coupling Between Thiols and Arylboronic Acids Leading to Diaryl Sulfides under Mild Conditions.

Abstract The heterogeneous Chan-Lam coupling reaction between thiols and arylboronic acids was achieved in EtOH at room temperature in the presence of 5 mol % of MCM-41-immobilized 1,10-phenanthroline-copper(II) complex [MCM-41-1,10-Phen-CuSO4] with n-Bu4NOH (40% aq) as base under O2 atmosphere, yielding a variety of unsymmetrical diaryl sulfides in good to excellent yields under mild and green conditions. The new heterogeneous copper complex can easily be prepared by a simple procedure from commercially readily available and inexpensive reagents, and recovered by a simple filtration of the reaction solution and recycled for at least eight times without significant loss of catalytic activity.

Aqueous Suzuki Coupling Reactions of Basic Nitrogen-Containing Substrates in the Absence of Added Base and Ligand: Observation of High Yields under Acidic Conditions

A series of aqueous heterogeneous Suzuki coupling reactions of substrates containing basic nitrogen centers with phenylboronic acid in the absence of added base and ligand is presented. High yields of products were obtained by employing aryl bromides containing aliphatic 1°, 2°, and 3° amine substituents, and good to high yields were obtained by employing a variety of substituted bromopyridines. In the former series, the pH of the aqueous phase changed from basic to acidic during the course of the reaction, while in the latter series the aqueous phase was on the acidic side of the pH scale throughout the entire course of reaction. A mechanistic interpretation for these observations, which generally preserves the oxo palladium catalytic cycle widely accepted in the literature, is presented.

Chimera states in two populations with heterogeneous phase-lag.

The simplest network of coupled phase-oscillators exhibiting chimera states is given by two populations with disparate intra- and inter-population coupling strengths. We explore the effects of heterogeneous coupling phase-lags between the two populations. Such heterogeneity arises naturally in various settings, for example, as an approximation to transmission delays, excitatory-inhibitory interactions, or as amplitude and phase responses of oscillators with electrical or mechanical coupling. We find that breaking the phase-lag symmetry results in a variety of states with uniform and non-uniform synchronization, including in-phase and anti-phase synchrony, full incoherence (splay state), chimera states with phase separation of 0 or π between populations, and states where both populations remain desynchronized. These desynchronized states exhibit stable, oscillatory, and even chaotic dynamics. Moreover, we identify the bifurcations through which chimeras emerge. Stable chimera states and desynchronized solutions, which do not arise for homogeneous phase-lag parameters, emerge as a result of competition between synchronized in-phase, anti-phase equilibria, and fully incoherent states when the phase-lags are near ±π2 (cosine coupling). These findings elucidate previous experimental results involving a network of mechanical oscillators and provide further insight into the breakdown of synchrony in biological systems.

The abatement of fine particles from desulfurized flue gas by heterogeneous vapor condensation coupling two impinging streams

A novel process was proposed for fine particles abatement via heterogeneous vapor condensation coupling two impinging steams (TIS) technique in this paper. The essential supersaturation was established by adding steam or humid air into desulfurized flue gas, and the application of TIS technique in this process made the mixture of desulfurized flue gas and humid air or steam more sufficient. The fine particles were enlarged by the heterogeneous vapor condensation and the collision-coalescence in two impinging steams condensational growth chamber (TISCGC), then the enlarged fine particles were intercepted by a wire mesh demister at the top of TISCGC. The results indicated that the enlargement of fine particles in TISCGC was more significant than that of conventional condensational growth chamber (CCGC), thus the fine particle removal performance of wire mesh demister was better. The removal performance of fine particles by this process was influenced by many factors, such as flue gas velocity of opposing jets in TISCGC, additive amount of steam or humid air and the desulfurized flue gas temperature. Under the optimum conditions, the removal efficiency of TISCGC could be increased to 50–60% by using this process.

Suppression of Chaos Time Delay Signature in a Ring Network Consisting of Three Semiconductor Lasers Coupled With Heterogeneous Delays

The properties of chaos time delay signature (TDS) in a ring network consisting of three mutually coupled semiconductor lasers (MCSLs) are investigated numerically, where heterogeneous coupling delays are proposed to obtain the TDS concealment from the intensity chaos in wide parameter regions. The evolution of the TDS patterns, which are quantified via the autocorrelation function, for a ring network with identical coupling delays as well as that with heterogeneous coupling delays is compared. By analyzing the effects of the coupling strength, frequency detuning, and injection current on the TDS, the parameter regions for successful TDS concealment are identified. It is found that the intensity chaos with a desirable TDS concealment can be generated in the proposed ring network in which the TDS is mainly affected by the injection current and coupling strength, but is not so sensitive to the frequency detuning. In particular, a larger injection current and smaller coupling strength are preferable to obtain chaos with a low TDS. Besides, the ring network with heterogeneous coupling delays allows for better TDS concealment in much wider parameter regions, compared to that with identical coupling delays, and, thus, is highly desirable for the chaos-based random bit generators.

Global cluster synchronization in nonlinearly coupled community networks with heterogeneous coupling delays

This investigation establishes the global cluster synchronization of complex networks with a community structure based on an iterative approach. The units comprising the network are described by differential equations, and can be non-autonomous and involve time delays. In addition, units in the different communities can be governed by different equations. The coupling configuration of the network is rather general. The coupling terms can be non-diffusive, nonlinear, asymmetric, and with heterogeneous coupling delays. Based on this approach, both delay-dependent and delay-independent criteria for global cluster synchronization are derived. We implement the present approach for a nonlinearly coupled neural network with heterogeneous coupling delays. Two numerical examples are given to show that neural networks can behave in a variety of new collective ways under the synchronization criteria. These examples also demonstrate that neural networks remain synchronized in spite of coupling delays between neurons across different communities; however, they may lose synchrony if the coupling delays between the neurons within the same community are too large, such that the synchronization criteria are violated.

Heterogeneous copper-catalyzed coupling of amines: a possible way for the preparation of imines

Copper(II) on 4-A molecular sieves is an efficient catalyst for the preparation of imines from benzylamines under simple reaction conditions. No oxidative atmosphere or oxidizing agents are required. Preparative experiments showed that no aldehyde intermediate can be detected even under ambient atmospheric conditions.

Sensitivity Tuning through Additive Heterogeneous Plasmon Coupling between 3D Assembled Plasmonic Nanoparticle and Nanocup Arrays.

Plasmonic substrates have fixed sensitivity once the geometry of the structure is defined. In order to improve the sensitivity, significant research effort has been focused on designing new plasmonic structures, which involves high fabrication costs; however, a method is reported for improving sensitivity not by redesigning the structure but by simply assembling plasmonic nanoparticles (NPs) near the evanescent field of the underlying 3D plasmonic nanostructure. Here, a nanoscale Lycurgus cup array (nanoLCA) is employed as a base colorimetric plasmonic substrate and an assembly template. Compared to the nanoLCA, the NP assembled nanoLCA (NP-nanoLCA) exhibits much higher sensitivity for both bulk refractive index sensing and biotin-streptavidin binding detection. The limit of detection of the NP-nanoLCA is at least ten times smaller when detecting biotin-streptavidin conjugation. The numerical calculations confirm the importance of the additive plasmon coupling between the NPs and the nanoLCA for a denser and stronger electric field in the same 3D volumetric space. Tunable sensitivity is accomplished by controlling the number of NPs in each nanocup, or the number density of the hot spots. This simple yet scalable and cost-effective method of using additive heterogeneous plasmon coupling effects will benefit various chemical, medical, and environmental plasmon-based sensors.

Heterogeneity and nearest-neighbor coupling can explain small-worldness and wave properties in pancreatic islets.

Many multicellular systems consist of coupled cells that work as a syncytium. The pancreatic islet of Langerhans is a well-studied example of such a microorgan. The islets are responsible for secretion of glucose-regulating hormones, mainly glucagon and insulin, which are released in distinct pulses. In order to observe pulsatile insulin secretion from the β-cells within the islets, the cellular responses must be synchronized. It is now well established that gap junctions provide the electrical nearest-neighbor coupling that allows excitation waves to spread across islets to synchronize the β-cell population. Surprisingly, functional coupling analysis of calcium responses in β-cells shows small-world properties, i.e., a high degree of local coupling with a few long-range "short-cut" connections that reduce the average path-length greatly. Here, we investigate how such long-range functional coupling can appear as a result of heterogeneity, nearest-neighbor coupling, and wave propagation. Heterogeneity is also able to explain a set of experimentally observed synchronization and wave properties without introducing all-or-none cell coupling and percolation theory. Our theoretical results highlight how local biological coupling can give rise to functional small-world properties via heterogeneity and wave propagation.

A highly efficient heterogeneous copper-catalyzed Chan-Lam coupling between thiols and arylboronic acids leading to diaryl sulfides under mild conditions

The heterogeneous Chan-Lam coupling reaction between thiols and arylboronic acids was achieved in EtOH at room temperature in the presence of 5 mol % of MCM-41-immobilized 1,10-phenanthroline-copper(II) complex [MCM-41-1,10-Phen-CuSO4] with n-Bu4NOH (40% aq) as base under O2 atmosphere, yielding a variety of unsymmetrical diaryl sulfides in good to excellent yields under mild and green conditions. The new heterogeneous copper complex can easily be prepared by a simple procedure from commercially readily available and inexpensive reagents, and recovered by a simple filtration of the reaction solution and recycled for at least eight times without significant loss of catalytic activity.

Event-Triggered Master–Slave Synchronization With Sampled-Data Communication

In this brief, the event-triggered synchronization is investigated for a class of heterogeneous master-slave coupling systems consisting of a high-dimensional master system but a low-dimensional slave system. An event-triggered sampled-data transmission strategy is designed, which allows the event-triggered condition to be examined only at sampling instants. With the assumption that only some sampled-data outputs of the master system are available to the slave system, a kind of observer-based synchronization controller is constructed and utilized. Based on a delayed-input approach, the master-slave synchronization problem is equivalently converted into the asymptotical stability problem of a time-delay system. By constructing an appropriate Lyapunov-Krasovskii functional and employing the free-weighting matrix approach, some sufficient synchronization criteria in terms of linear matrix inequalities are derived. Numerical simulations are finally provided to verify the theoretical results.

Muscle-on-chip: An in vitro model for donor-host cardiomyocyte coupling.

A key aspect of cardiac cell–based therapy is the proper integration of newly formed cardiomyocytes into the remnant myocardium after injury. In this issue, Aratyn-Schaus et al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201508026) describe an in vitro model for heterogeneous cardiomyocyte coupling in which force transmission between cells can be measured.

A highly efficient heterogeneous copper-catalyzed three-component coupling of tetrahydroisoquinolines, aldehydes and 1-alkynes

A highly efficient heterogeneous copper-catalyzed three-component coupling of tetrahydroisoquinolines, aldehydes and 1-alkynes has been described.

Evanescent coupling between surface and linear-defect guided modes in phononic crystals

Evanescent coupling between surface and linear-defect waveguide modes in a two-dimensional phononic crystal of steel cylinders in air is numerically demonstrated. When the ratio of scatterer radii to the lattice constant is set to 0.47 in the square phononic crystal, the two types of modes start interacting if there is one-row separation between the surface and waveguide. Supercell band structure computations through the Finite Element Method suggest that the waveguide band is displaced significantly, whereas the surface band remains almost intact when the waveguide and surface are in close proximity. The two resultant hybrid bands are such that the coupling length, which varies between 8 and 22 periods, initially changes linearly with frequency, while a much sharper variation is observed towards the top of the lower hybrid band. Such small values facilitate the design of compact devices based on heterogeneous coupling. Finite-element simulations demonstrate bilateral coupling behaviour, where waves incident from either the surface or waveguide can efficiently couple to the other side. The coupling lengths calculated from simulation results are in agreement with the values predicted from the supercell band structure. The possible utilisation of the coupling scheme in sensing applications, especially in acoustic Doppler velocimetry, is discussed.