Types Of Junctions Research Articles

Pure valley and spin polarization current in ferromagnetic graphene junction

We investigate the band structure and spin- and valley-dependent transport in ferromagnetic graphene double junctions using the transfer matrix method. The ferromagnetic double junctions include a lateral layout of normal/magnetic vector potential/normal/effective exchange field/normal graphene regions. We find that the strain combined with magnetic vector potentials breaks the valley degeneracy, and the strain combined with the effective exchange field breaks the spin degeneracy, so that there exists a spin- and valley-dependent gap in the ferromagnetic graphene double junctions, which allows only one spin species with special valley characteristics to be transported. Thus, this type of junction can achieve simultaneously pure spin- and pure valley-polarized currents and function as a perfect valley filter and a perfect spin filter. The exact nature of the valley filtering and spin filtering can be tuned by the strain, magnetic barrier, and effective exchange field strength.

Identification of KIAA1210 as a novel X-chromosome-linked protein that localizes to the acrosome and associates with the ectoplasmic specialization in testes.

Cell junctions are necessary for spermatogenesis, and there are numerous types of junctions in testis, such as blood–testis barrier, intercellular bridge, and ectoplasmic specialization (ES). The details of their functions and construction are still unknown. To identify a novel protein essential to the function of a cell junction, we enriched testis membrane protein and analyzed it using a proteomics approach. Here, we report a novel ES protein, which is encoded on the X chromosome and an ortholog of hypothetical human protein KIAA1210. KIAA1210 is expressed in testis predominantly, localized to the sex body in spermatocyte, acrosome, and near ES. Moreover, KIAA1210 possesses a topoisomerase 2 (TOP2)-associated protein PAT1 domain, a herpes simplex virus 1 (HSV-1) large tegument protein UL36 hypothetical domain, and a provisional DNA translocase FtsK domain. Using IP-proteomics with specific antibody to KIAA1210, we identified proteins including TOP2 isoforms as components of a complex with KIAA1210, in cell junctions in testis. The interaction between KIAA1210 and TOP2 was confirmed by two different proteomic analyses. Furthermore, immunofluorescence showed that KIAA1210 and TOP2B co-localize around the sex body in spermatocyte, apical ES, and residual bodies in elongated spermatids. Our findings suggest that KIAA1210 may be essential cell junction protein that interacts with TOP2B to regulate the dynamic change of chromatin structures during spermiogenesis.

Towards the Predicted High Performance of Waveguide Integrated Electro-Refractive Phase Modulators Based on Graphene

Here in this work, we study the electro-refractive modulation of CVD grown single layer graphene placed on top of a silicon microring resonator biased using a polymer electrolyte gate. A voltage length product for a phase shift of π, VπL = 2.7 Vmm has been extracted, which is better compared to silicon depletion horizontal and interleaved pn junction type phase modulators and competitive with Silicon-Insulator-Silicon Capacitor modulators.

On the design and optimization of acoustic network resonators for tire/road noise reduction

In this work we propose a numerical method for the calculation of resonant frequencies of network resonators and we also present an optimization method based on genetic algorithms to get targeted resonant frequencies of the network resonators. We can optimize parameters of the network structure such as junction types and end positions. Experiments are conducted on optimized wooden network resonators to validate the method. Good agreement is found between the measured and targeted resonant frequencies. Applications to tire/road noise are considered.

The Role of Interfaces in Heterostructures.

Nanocomposites represent an interesting class of materials because their applications are of multidisciplinary importance. Herein, interactions at the interface of heterostructures, leading to superior performance and sometimes to synergistic interactions, are highlighted. Although the types of junctions seem to be similar in different fields, the requirements for their function is device-dependent and thus no generally valid recipe can be utilized. Nonetheless, the overlap between research fields unveils the unique opportunity to combine the different knowledge and expertise as an inspiration to designing new composites for photoelectrochemical water splitting, photocatalysis, chemoresistive sensors, batteries, and composite multiferroics. A non-comprehensive overview is provided with focus on selected examples to highlight the concepts behind these nanojunctions.

Monte Carlo simulation of the kinetics of decomposition and the formation of precipitates at grain boundaries of the general type in dilute BCC Fe–Cu alloys

The kinetics of decomposition of a polycrystalline Fe–Cu alloy and the formation of precipitates at the grain boundaries of the material have been investigated theoretically using the atomistic simulation on different time scales by (i) the Monte Carlo method implementing the diffusion redistribution of Cu atoms and (ii) the molecular dynamics method providing the atomic relaxation of the crystal lattice. It has been shown that, for a small grain size (D ~ 10 nm), the decomposition in the bulk of the grain is suppressed, whereas the copper-enriched precipitates coherently bound to the matrix are predominantly formed at the grain boundaries of the material. The size and composition of the precipitates depend significantly on the type of grain boundaries: small precipitates (1.2–1.4 nm) have the average composition of Fe–40 at % Cu and arise in the vicinity of low-angle grain boundaries, while larger precipitates that have sizes of up to 4 nm and the average composition of Fe–60 at % Cu are formed near grain boundaries of the general type and triple junctions.

Ключевой алгоритм метода частичных областей в анализе резонансных штырей, тройниковых, турникетных и некоторых других многоплечих соединений

Ключевой алгоритм метода частичных областей в анализе резонансных штырей, тройниковых, турникетных и некоторых других многоплечих соединений

Fabrication and characterization of thermochemical hydrogen sensor with laminated structure

In this study, we reported the simple and cost-effective fabrication of thermochemical hydrogen (TCH) sensors composed of chalcogenide thin films and Pt/Al2O3 powders. Chalcogenide thin films of two types, composed of Bi2Te3 (monomorphic-type) and Bi2Te3Sb2Te3 (four-leg PN junction-type), were prepared by electrochemical deposition. The Pt/Al2O3 powder, which acts as a heating catalyst, was synthesized by impregnation of an Al2O3 powder with an aqueous solution of platinum (IV) chloride pentahydrate. Its heating process was optimized via a hydrogen-sensing evaluation to control the size of the Pt particles. The monomorphic-type TCH sensor showed an output signal of 14.2 μV in response to 10 vol% hydrogen gas, whereas an output signal of 39.6 μV was obtained from a four-leg PN junction–type TCH sensor. Even though the n–p junction-type had the same deposition area as that of the monomorphic-type, the output signal of the n–p junction TCH sensor was greater by a factor of 2.8. In addition, the monomorphic-type TCH sensor had an inferior response time (T90) of 31 s and a longer recovery time (D10) of 38 s; the four-leg PN junction-type TCH sensor had a lowest response time of 27 s and a fastest recovery time of 9 s (in 3% H2/air at room temperature).

Signatures of time-reversal-invariant topological superconductivity in the Josephson effect

For Josephson junctions based on s-wave superconductors, time-reversal symmetry is known to allow for powerful relations between the normal-state junction properties, the excitation spectrum, and the Josephson current. Here we provide analogous relations for Josephson junctions involving one-dimensional time-reversal-invariant topological superconductors supporting Majorana-Kramers pairs, considering both topological-topological and s-wave-topological junctions. Working in the regime where the junction is much shorter than the superconducting coherence length, we obtain a number of analytical and numerical results that hold for arbitrary normal-state conductance and the most general forms of spin-orbit coupling. The signatures of topological superconductivity we find include the fractional ac Josephson effect, which arises in topological-topological junctions provided that the energy relaxation is sufficiently slow. We also show, for both junction types, that robust signatures of topological superconductivity arise in the dc Josephson effect in the form of switches in the Josephson current due to zero-energy crossings of Andreev levels. The junction spin-orbit coupling enters the Josephson current only in the topological-topological case and in a manner determined by the switch locations, thereby allowing quantitative predictions for experiments with the normal-state conductance, the induced gaps, and the switch locations as inputs.

Hygrothermal aging effects on shear behavior of pultruded FRP composite web-flange junctions in bridge application

Abstract This paper reports the outcome of the third phase of a multi-phase comprehensive study that aimed at characterizing both short- and long-term behavior of web-flange junctions (WFJs) of pultruded fiber reinforced polymer (PFRP) commonly used in bridge applications. Both monolithic and adhesively-bonded junctions were evaluated. The focus of this paper is on shear characteristics of such junctions before and after exposure to hygrothermal aging. In this study, a total of eighteen shear tests were performed on as-built (unexposed) WFJ specimens, in addition to seventy-six shear tests that were conducted on other specimens that were exposed to both fresh water and artificial seawater environments at temperatures of 40 °C, 60 °C, and 80 °C in order to characterize shear behavior of six types of pultruded web/flange junctions and hygrothermal aging effect of one type of these web-flange junctions. Experimental results showed that increasing the web thickness of the pultruded member has an impact on junction's shear stiffness, however, increasing both flange thickness and junction's fillet radius have less effect on web-flange junctions' shear strength and stiffness. The difference in ultimate shear strength degradation of specimens exposed to freshwater and artificial seawater environments, at temperatures of 40 °C, and 80 °C is relatively small, however, the ultimate shear strength of WFJ specimens exposed to fresh-water environment degraded slightly higher as compared to specimens that were immersed in artificial seawater environment at 60 °C temperature. The difference in mechanical properties degradation at different temperatures was found to be relatively small (from 0.0 h to 672.0 h). However, a relatively higher degradation was observed at higher temperatures during an exposure period from 672.0 h to 4392.0 h. Moreover, the hygrothermal effects on axial, shear and rotation behaviors of web-flange junctions were compared. Based on the results of the three-phases of this multi-phase study, it was shown that the degradation of WFJ's moment capacity is the largest, the reduction in axial capacity is the least and the shear capacity degradation is in the middle when junctions are exposed to both water and artificial seawater aging environments at temperatures of 40 °C, 60 °C and 80 °C.

Impact of contact couplings on thermoelectric properties of anti, Fano, and Breit-Wigner resonant junctions

Quantum interference is a well-known phenomenon which results in unique features of the transmission spectra of molecular junctions at the nanoscale. We investigate and compare the thermoelectric properties of three types of junctions like the anti, Breit-Wigner, and Fano resonances. Due to its asymmetric line-shaped transmission function, Fano resonances lead to a larger thermoelectric figure of merit (ZT) than the symmetric anti and Breit-Wigner resonances. The occurrence of quantum interference in molecular and other nanoscale junctions is independent of contact couplings between the sandwiched molecules and left/right electrodes. However, it is found that the contact couplings determine the electric and thermoelectric performances of quantum interference junctions. In anti-resonant junctions, the Seebeck coefficient is enhanced by strong contact couplings. By contrast, for Breit-Wigner resonant junctions, this same property will increase in the weak contact coupling regime. Contrary to what is observed for anti and Breit-Wigner resonant junctions, some optimal contact couplings are found in Fano-resonant junctions for which the maximum Seebeck coefficient and ZT are obtained. Finally, thermoelectric properties are also investigated when the resonances crossover from Breit-Wigner to Fano types and, subsequently, to anti resonances.

Modeling the rheological properties of highly nano-filled polymers

Organic and inorganic materials are usually added to polymers in order to achieve some benefits such as reducing the product cost, as well as achieving higher modulus and strength. Addition of these materials would change polymers’ behavior. Adding nano-materials to polymers on the other hand is a new challenge in the field of polymer composites where previous studies were unable to achieve good correlation with nano-composites at higher particle volume fractions. In this research, Yamamoto network theory is developed to investigate the behavior of highly nano-filled systems. For this purpose, five different types of sub-chain and two types of junctions are considered and the effect of particle size, concentration, and the model parameters in association with the behavior of the junctions are studied. Moreover, some experiments are performed on polystyrene filled with nano-silica at different particle size and concentration values in frequency mod in the linear region. At last, we compared the results of our final model with the experiments in order to evaluate its accuracy, which confirmed a very good agreement.

Shear zone junctions: Of zippers and freeways

Ductile shear zones are commonly treated as straight high-strain domains with uniform shear sense and characteristic curved foliation trails, bounded by non-deforming wall rock. Many shear zones, however, are branched, and if movement on such branches is contemporaneous, the resulting shape can be complicated and lead to unusual shear sense arrangement and foliation geometries in the wall rock. For Y-shaped shear zone triple junctions with three joining branches and transport direction at a high angle to the branchline, only eight basic types of junction are thought to be stable and to produce significant displacement. The simplest type, called freeway junctions, have similar shear sense in all three branches. The other types show joining or separating behaviour of shear zone branches similar to the action of a zipper. Such junctions may have shear zone branches that join to form a single branch (closing zipper junction), or a single shear zone that splits to form two branches, (opening zipper junction). All categories of shear zone junctions show characteristic foliation patterns and deflection of markers in the wall rock. Closing zipper junctions are unusual, since they form a non-active zone with opposite deflection of foliations in the wall rock known as an extraction fault or wake. Shear zipper junctions can form domains of overprinting shear sense along their flanks. A small and large field example are given from NE Spain and Eastern Anatolia. The geometry of more complex, 3D shear zone junctions with slip parallel and oblique to the branchline is briefly discussed.

Vibrational analysis of single-walled carbon nanotube/graphene junctions using finite element modeling

Current study concerns the vibrational behavior of single-walled carbon nanotube/graphene junctions using the finite element method. The effects of different parameters including nanotube and graphene geometry/boundary conditions on the vibrations of nanotube/graphene junction are investigated. Two types of junctions are considered. In the first type, the nanotube is connected to one side of graphene, while in the second type, both sides of the graphene are connected to nanotubes. It is shown that increasing the height-to-length ratio of graphene results in decreasing the fundamental natural frequency of the junctions. When the boundary conditions are imposed on the graphene, increasing the radius of carbon nanotube leads to decreasing the frequency. Moreover, the frequencies of the second type models are larger than those of the first type.

Electro-Optical Ring Modulator: An Ultracompact Model for the Comparison and Optimization of p-n, p-i-n, and Capacitive Junction

Silicon photonics electro-optical ring modulators are key components in short-range optical interconnects, as they can be operated at low-voltage, compatible with CMOS circuit drivers. However, a full exploration of design tradeoffs is currently lacking. In this paper, a semianalytical simulation scheme is proposed for the optimization and comparison of different kinds of silicon ring modulator junction. We first describe the physical parameters used in the conventional models of active ring resonators, and apply the model to the case of carrier depletion in the well-known p-n junction. The same approach is applied to both p-i-n and capacitive junctions, and leads to a comparison of each type of modulation junction in which the strengths and weaknesses of each configuration are highlighted. We then propose a compact optimization model that directly provides the best opto-geometrical compromise between high modulation efficiency, low optical losses and large bandwidth.

Out-of-Plane Directional Charge Transfer-Assisted Chemical Enhancement in the Surface-Enhanced Raman Spectroscopy of a Graphene Monolayer

We present an out-of-plane directional charge transfer (CT)-assisted chemical enhancement (CM) in the surface-enhanced Raman scattering (SERS) of a graphene monolayer (GM) sandwiched at an individual Au prism-Au thin film (TF) plasmonic junction. By comparing previous reports, in which the enhancement of out-of-plane phonon modes of a GM was mostly governed by z-directional local field formed at a Au nanoparticle (NP)–Au TF junction, we can reveal that a CT-assisted CM along the z-direction has a pivotal role by enhancing radial breathing-like mode (RBLM) intensity at face-to-face junction types. The anticorrelation between 2D and RBLM intensity from ridge to flat domains of an Au prism indicates that a plasmonic EM effect is not a critical element at flat domain, whereas the RBLM intensity is strongly enhanced at face-to-face junction. Furthermore, the closest GM from a z-axis has a significant role based on vector-based investigation in enhancing CT-assisted CM effect between Au prism and TF. These phen...

Plasticity-induced restructuring of a nanocrystalline grain boundary network

The grain boundary-mediated mechanisms that control plastic deformation of nanocrystalline metals should cause evolution of the grain boundary network, since they directly alter misorientation relationships between crystals. Unfortunately, current experimental techniques are unable to track such evolution, due to limits on both spatial and temporal resolution. In this work, molecular dynamics simulations are used to study grain boundary restructuring in nanocrystalline Al during both monotonic tension and cyclic loading. This task is enabled by the creation of new analysis tools for atomistic datasets that allow for a complete characterization and tracking of microstructural descriptors of the grain boundary network. Quantitative measurements of grain boundary character distribution, triple junction type, grain boundary plane normal, and other interfacial network characteristics are extracted and analyzed. The results presented here show that nanocrystalline plasticity leads to an increase in special boundary fraction and disruption of two-dimensional boundary connectivity, with the most dramatic evolution occurring in the smallest grain sizes.

Block Co-PolyMOCs by Stepwise Self-Assembly.

We report a stepwise assembly strategy for the integration of metal-organic cages (MOCs) into block copolymers (BCPs). This approach creates "block co-polyMOC" (BCPMOC) materials whose microscopic structures and mechanical properties are readily tunable by adjusting the size and geometry of the MOCs and the composition of the BCPs. In the first assembly step, BCPs functionalized with a pyridyl ligand on the chain end form star-shaped polymers triggered by metal-coordination-induced MOC assembly. The type of MOC junction employed precisely determines the number of arms for the star polymer. In the second step, microphase separation of the BCP is induced, physically cross-linking the star polymers and producing the desired BCPMOC networks in the bulk or gel state. We demonstrate that large spherical M12L24 MOCs, small paddlewheel M2L4 MOCs, or a mixture of both can be incorporated into BCPMOCs to provide materials with tailored branch functionality, phase separation, microdomain spacing, and mechanical properties. Given the synthetic and functional diversity of MOCs and BCPs, our method should enable access to BCPMOCs for a wide range of applications.

A Role for DLK in Microtubule Reorganization to the Cell Periphery and in the Maintenance of Desmosomal and Tight Junction Integrity

Dual leucine zipper-bearing kinase (DLK) is an inducer of keratinocyte differentiation, a complex process also involving microtubule reorganization to the cell periphery. However, signaling mechanisms involved in this process remain to be elucidated. Here, we demonstrate that DLK enhances and is required for microtubule reorganization to the cell periphery in human cell culture models and in Dlk knockout mouse embryos. In tissue-engineered skins with reduced DLK expression, cortical distribution of two microtubule regulators, LIS1 and HSP27, is impaired as well as desmosomal and tight junction integrity. Altered cortical distribution of desmosomal and tight junction proteins was also confirmed in Dlk knockout mouse embryos. Finally, desmosomal and tight junction defects were also observed after microtubule disruption in nocodazole-treated tissue-engineered skins, thus confirming a role for microtubules in the maintenance of these types of cell junctions. Globally, this study demonstrates that DLK is a key regulator of microtubule reorganization to the cell periphery during keratinocyte differentiation and that this process is required for the maintenance of desmosomal and tight junction integrity.

Exploring the characteristics of potential and current users of mobility scooters, among older people in Israel

Recognizing the decline in the ability of older people to serve as vehicle drivers and their physical limitations for long walks, mobility scooters are considered as an alternative mobility means for older people. An increasing popularity of scooters is recently being observed in Israel, raising safety concerns. This study explored the characteristics of potential users of mobility scooters among older people in Israel and the behaviours of their current users, by means of an opinion survey and field observations in urban areas. The opinion survey applied structured interviews, with 110 persons aged 65+. The survey's results showed that most people agreed that scooters may improve their mobility and quality of life. However, they expressed a relatively low willingness to use scooters, mostly, due to the preference for private cars but also the lack of appropriate infrastructure for safe scooter travel in the city. An increasing potential for scooters' use was associated with ages 70–84, people who are aware of their health problems and less involved in physical activities but still maintain an active lifestyle, living independently and appreciating scooter benefits. The observations included 55 video-records with older scooter riders. They showed that regardless the types of urban road or junction, the majority of scooter riders behaved like a vehicle, i.e. travelled on the roadway. Scooters' moving on a sidewalk did not create conflicts with pedestrians, while scooters travelling on the roads sometimes disturbed vehicle flows and created dangerous situations. To ensure safety of the scooter users, their travels on the sidewalks should be stimulated and, thus, appropriate adjustments of urban infrastructure are required.