Regulation of phonon localization on thermal transport in complex networks.

The regulation of thermal transport is a challenging topic in complex networks. At present, the hidden physical mechanism behind thermal transport is poorly understood. This paper addresses this issue by proposing a complex network model that focuses on the thermal transport regulation through the manipulation of the network's degree distribution and clustering coefficient. Our findings indicate that increasing the degree distribution regulation parameter σ leads to reduced phonon localization and improved thermal transport efficiency. Conversely, increasing the clustering coefficient c results in enhanced phonon localization and reduced thermal transport efficiency. Meanwhile, by calculating the pseudodispersion relation of the network, we find that the maximum (or the second smallest) eigenfrequency decreases with increasing σ (or c). Finally, we elucidate that phonon localization plays a pivotal role in the thermal transport of the network, as demonstrated through density of states and the participation ratio.

Critical transition of thermal rectification on complex networks.

Thermal rectification is a mechanism that controls the direction of heat conduction, allowing it to flow freely in one direction and hindering it in the opposite direction. In this study, we propose a heat conduction model on a complex network where the node masses are non-uniformly distributed according to mi∼kiα. Our findings show that the existence of a critical point, α=1, determines the working mode of thermal rectification. For α>1, the working mode of thermal rectification is positive, whereas for α<1, the working mode is negative. Additionally, we discovered that this critical transition is a general phenomenon and does not vary with changes in network size, average degree, or degree distribution. By conducting theoretical analyses based on phonon spectra, we also identified the physical mechanism of the critical transition. These results provide a new approach to implement and enrich thermal diodes, opening up new possibilities for more efficient thermal management.

Ab initio study of the topological itinerant transport properties observed between excited edge states in a 2D compound with the Mn15B16Ni composition.

We theoretically demonstrate how the competition between band inversion and spin-orbit coupling (SOC) results in the nontrivial topology of band evolution, using two-dimensional (2D) Mn16B16 as a matrix. This study utilizes the ab initio method with the generalized gradient approximation (GGA+U scheme) and Wannier functions to investigate the topological and transport properties of the Ni-doped structure. The Ni atom induces dynamical antilocalization, which appears due to the phase accumulation between time-reversed fermion loops. A key observation is that when band inversion dominates over SOC, "twin" Weyl cones appear in the band structure, in which the Weyl cones caused by the large Berry curvature coupling with the net magnetization lead to the significantly enhanced anomalous Hall conductivity (AHC). Interestingly, the nested small polaron and energy band inversion coexist with SOC. An analysis of the projected energy band shows that the doped Ni atom induces a strong spin wave for both spin up and spin down.

Phononic band gap in random spring networks.

We investigate the relation between topological and vibrational properties of networked materials by analyzing, both numerically and analytically, the properties of a random spring network model. We establish a pseudodispersion relation, which allows us to predict the existence of distinct transitions from extended to localized vibrational modes in this class of materials. Consequently, we propose an alternative method to control phonon and elastic wave propagation in disordered networks. In particular, the phonon band gap of our spring network model can be enhanced by either increasing its average degree or decreasing its assortativity coefficient. Applications to phonon band engineering and vibrational energy harvesting are briefly discussed.

Regulating heat conduction of complex networks by distributed nodes masses.

Developing efficient strategy to regulate heat conduction is a challenging problem, with potential implication in the field of thermal materials. We here focus on a potential thermal material, i.e. complex networks of nanowires and nanotubes, and propose a model where the mass of each node is assigned proportional to its degree with [Formula: see text], to investigate how distributed nodes masses can impact the heat flow in a network. We find that the heat conduction of complex network can be either increased or decreased, depending on the controlling parameter [Formula: see text]. Especially, there is an optimal heat conduction at [Formula: see text] and it is independent of network topologies. Moreover, we find that the temperature distribution within a complex network is also strongly influenced by the controlling parameter [Formula: see text]. A brief theoretical analysis is provided to explain these results. These findings may open up appealing applications in the cases of demanding either increasing or decreasing heat conduction, and our approach of regulating heat conduction by distributed nodes masses may be also valuable to the challenge of controlling waste heat dissipation in highly integrated and miniaturized modern devices.

Corydaline and l-tetrahydropalmatine attenuate morphine-induced conditioned place preference and the changes in dopamine D2 and GluA1 AMPA receptor expression in rats.

Corydalis is a Chinese herb that has been used in China for hundreds of years for analgesic and other purposes. Corydaline and l-tetrahydropalmatine (l-THP) are the main active ingredients of Corydalis. This study was aimed to study the potential utility of corydaline and l-THP in the treatment of opioid abuse and addiction and explore the possible mechanisms underlying their pharmacological actions. Conditioned place preference (CPP) was used to evaluate the rewarding effects of morphine and Western-blot immunoreactive assays were used to evaluate morphine-induced changes in dopamine D2 receptor and GluA1 AMPA receptor and GluA2 AMPA receptor expression in the brain of rats. Systemic administration of corydaline (5 mg/kg, i.p.) or l-THP (1.25, 2.5,5 mg/kg) significantly inhibited the acquisition and expression of morphine-induced CPP in a dose-dependent manner. Corydaline or l-THP alone, at the same doses, failed to produce CPP or conditioned place aversion, and didn't affect locomotor activity. We then examined the expression of dopamine D2 receptor and GluA1 AMPA receptor and GluA2 AMPA receptor subunit expression in rats after acquisition of morphine-induced CPP. We found that repeated administration of morphine produced a significant reduction in dopamine D2 receptor expression in the prefrontal cortex, hippocamps, and striatum, while an increase in the striatal GluA1 AMPA receptor expression. Pretreatment with corydaline or l-THP blocked morphine-induced dopamine D2 receptor down-regulation and GluA1 AMPA receptor up-regulation in these brain regions. Corydaline and l-THP may have therapeutic potential in prevention and treatment of opioid abuse and addiction. The underlying mechanisms may be related to their antagonism on morphine-induced changes in dopamine and glutamate transmission in the brain.

Thermal-siphon phenomenon and thermal/electric conduction in complex networks.

In past decades, a lot of studies have been carried out on complex networks and heat conduction in regular lattices. However, very little attention has been paid to the heat conduction in complex networks. In this work, we study (both thermal and electric) energy transport in physical networks rewired from 2D regular lattices. It is found that the network can be transferred from a good conductor to a poor conductor, depending on the rewired network structure and coupling scheme. Two interesting phenomena were discovered: (i) the thermal-siphon effect-namely the heat flux can go from a low-temperature node to a higher-temperature node and (ii) there exits an optimal network structure that displays small thermal conductance and large electrical conductance. These discoveries reveal that network-structured materials have great potential in applications in thermal-energy management and thermal-electric-energy conversion.

Influence of the degree of a complex network on heat conduction.

Devices made of nanotubes and nanowires networks are of great interest for applications and have caught increasing attention in recent years. In this work, we study heat conduction in a network model with nodes being atoms and links being one-dimensional chains of atoms. It is found that heat conduction in the complex network is fundamentally different from that of regular lattices. It depends very sensitively on the average degrees of complex networks and the degrees of nodes that are attached to the two heat baths. For example, when the two heat source nodes have the same degree k_{0}, the heat flux reaches a maximum at an optimized value of k_{0} and decreases with the increase of the average degree 〈k〉. In other words, the source nodes with optimal degree k_{0} and the sparse network are more favorable to heat flux. Thermal rectification effect is found when the two heat source nodes have different degrees or the network model has multiple heat source nodes. Theoretical analysis is provided to explain the numerical results.