Two-way Switch Research Articles

Valley switch effect based on monolayer WSe2 modulated by circularly polarized light and valley Zeeman field

The high-quality monolayer (ML) WSe2 leads to the possibility of an efficient manipulation of the spin and valley degrees of freedom. Here considering valley Zeeman field, which refers to the strongly anisotropic lifting of the degeneracy of the valley pseudospin degree of freedom using an external magnetic field, we investigate the spin and valley transport properties in the ML WSe2 quantum structure with circularly polarized light. Without valley Zeeman field, it is obviously found that the valley-dependent transmission can be well modulated by the orientation of circularly polarized light. The valley-dependent transmission can be filtered by the right () circularly polarized light, while the perfect filtering effect of K valley-dependent transmission occurs when the left () circularly polarized light irradiates. In the presence of valley Zeeman field, the valley-dependent transmission presents more interesting phenomena by controlling the orientation of circularly polarized light. When the circularly polarized light is applied, the valley polarization can be turned 100% to −100% with the enhancement of the effective energy about circularly polarized light. However, irradiating the circularly polarized light only 100% valley polarization can be obtained, which is independent of the effective energy of circularly polarized light and the height of electric barrier. Moreover, the results show that the valley polarization can also be from 100% to −100% in this device by adjusting the valley Zeeman field coupled with electrical field. Thus a two-way switch is formed in this quantum structure. These intriguing features indicate that the ML WSe2 structure is a promising candidate for future valleytronics devices, for valley switch, valley filter.

Two-way switch: Maximizing productivity of tilted panel in membrane bioreactor

Membrane fouling is a major challenge in membrane bioreactors (MBRs) and its effective handling is the key to improve their competitiveness. Tilting panel system offers significant improvements for fouling control but is strictly limited to one-sided panel. In this study, we assess a two-way switch tilting panel system that enables two-sided membranes and project its implications on performance and energy footprint. Results show that tilting a panel improves permeance by up to 20% to reach a plateau flux thanks to better contacts between air bubbles and the membrane surface to scour-off the foulant. A plateau permeance could be achieved at aeration rate of as low as 0.90 l min−1, a condition untenable by vertical panel even at twice of the aeration rate. Switching at short periods (<5min) can maintain the hydraulic performance as in no-switch (static system), enables application of a two-sided switching panel. A comparison of vertical panel under 1.80 l min−1 aeration rate with a switching panel at a half of the rate, switched at 1 min period shows ≈10% higher permeance of the later. Since periodic switching consumes a very low energy (0.55% of the total of 0.276 kWh m−3), with reduction of aeration by 50%, the switching tilted panel offers 41% more energy efficient than a referenced full-scale MBR (0.390 kWh m−3). Overall results are very compelling and highly attractive for significant improvements of MBR technologies.

Bipolar-type Dynamic Voltage Conditioner Using P-Leg and N-Leg Structured AC-AC Converter

The voltage fluctuation caused by the high proportion of residential photovoltaic (PV) grid-connected not only restricts the capacity of network to absorb renewable energy, but also seriously affects the normal operation of electrical equipment. Voltage problems in the low voltage distribution network with high proportion of residential PV are described and a novel bipolar-type dynamic voltage conditioner (B-DVC) is introduced to solve the voltage problem in this paper. The topology of the B-DVC adopts the positive current leg (P-Leg) and the negative current leg (N-Leg). By combining two separation inductors together, the voltage distortion caused by the traditional full-bridge two-way switch converter is overcome. Due to the use of the P-Leg and N-Leg structure, the B-DVC can be short- and open-circuited without damaging the switching devices. Neither lossy RC snubber nor a dedicated soft commutation strategy is required in the proposed B-DVC. Furthermore, B-DVC can not only output the voltage with the same polarity as the grid voltage, but also output the voltage opposite the polarity, which can ensure the stability of the power grid voltage and improve the capacity of grid to absorb renewable energy. A 10-kW prototype of single-phase B-DVC is developed, and its performance is experimentally verified.

Landscape reveals critical network structures for sharpening gene expression boundaries

BackgroundSpatial pattern formation is a critical issue in developmental biology. Gene expression boundary sharpening has been observed from both experiments and modeling simulations. However, the mechanism to determine the sharpness of the boundary is not fully elucidated.ResultsWe investigated the boundary sharpening resulted by three biological motifs, interacting with morphogens, and uncovered their probabilistic landscapes. The landscape view, along with calculated average switching time between attractors, provides a natural explanation for the boundary sharpening behavior relying on the noise induced gene state switchings. To possess boundary sharpening potential, a gene network needs to generate an asymmetric bistable state, i.e. one of the two stable states is less stable than the other. We found that the mutual repressed self-activation model displays more robust boundary sharpening ability against parameter perturbation, compared to the mutual repression or the self-activation model. This is supported by the results of switching time calculated from the landscape, which indicate that the mutual repressed self-activation model has shortest switching time, among three models. Additionally, introducing cross gradients of morphogens provides a more stable mechanism for the boundary sharpening of gene expression, due to a two-way switching mechanism.ConclusionsOur results reveal the underlying principle for the gene expression boundary sharpening, and pave the way for the mechanistic understanding of cell fate decisions in the pattern formation processes of development.

Zn doped δ-MnO2 nano flakes: An efficient electrode material for aqueous and solid state asymmetric supercapacitors

Asymmetric supercapacitors based on aqueous and solid-state electrolytes are useful for a variety of applications. The birnessite δ-MnO2 is one of the efficient materials from the MnOx family characterized by large interlayer distance (∼7.3 Å) and high theoretical specific capacitance (∼1370 F g−1). However the main concern which hinders its usage for practical applications is its low electronic conductivity (∼10−6 S cm−1). There are different means to enhance the conductivity and in the present studies, two simultaneous methods viz; a method of synthesis of nano-flakes along with Zn-doping in δ-MnO2 is implemented. A specific capacitance of ∼466 F g−1 at a current density of 0.5 A g−1 is obtained for an optimum Zn doping concentration of 1 mol% which is almost two times more than the corresponding pristine one. Both aqueous and solid-state asymmetric supercapacitor devices are fabricated using Zn doped δ-MnO2 as electrode material which can be easily scalable to industrial level. A lab-scale demonstration prototype is constructed which essentially validated the charging of solid-state supercapacitor using battery and allowing the supercapacitor to discharge through a red-LED by means of a two-way switch.

Switching alternating current (AC) using a fully screen‐printed current‐driven transistor

The authors report on a large area, fully screen-printed transistors, using nanostructured silicon as the active material. The transistors are produced by simple screen printing processes under ambient conditions without the need for post-processing steps. The devices can be operated as two-way switches both with a direct or alternating current (AC). The authors demonstrated the operation of the devices printed on flexible substrates (office paper 80 g/m2) using silver as the conductive electrodes and highly doped p-type nanostructured silicon as the active layer. A method of switching sinusoidal AC using a single printed transistor is demonstrated at a frequency of 50 Hz at ambient condition. The silicon used as active materials, present domains, and blocks at a microscopic level, with an electric behaviour similar to one of the varistor-like components used as surge suppressors. So, unlike conventional transistors which rely on electric field modulation or charge injection, these AC switches operate by activation transport of charge carriers in the active silicon layer. Switching AC is achieved by applying a signal to the base which results in a change of the current's direction from between the collector and base to between the base and emitter.

Targeted Activation of Molecular Transportation by Visible Light.

Regulated transportation of nanoscale objects with a high degree of spatiotemporal precision is a prerequisite for the development of targeted molecular delivery. In vitro integration of the kinesin-microtubule motor system with synthetic molecules offers opportunities to develop controllable molecular shuttles for lab-on-a-chip applications. We attempted a combination of the kinesin-microtubule motor system with push-pull type azobenzene tethered inhibitory peptides (azo-peptides) through which reversible, spatiotemporal control over the kinesin motor activity was achieved locally by a single, visible wavelength. The fast thermal relaxation of the cis-isomers of azo-peptides offered us quick and complete resetting of the trans-state in the dark, circumventing the requirement of two distinct wavelengths for two-way switching of kinesin-driven microtubule motility. Herein, we report the manipulation of selected, single microtubule movement while keeping other microtubules at complete rest. The photoresponsive inhibitors discussed herein would help in realizing complex bionanodevices.

Nonreciprocal quantum-state conversion between microwave and optical photons

Optomechanical quantum interfaces can be utilized to connect systems with distinctively different frequencies in hybrid quantum networks. Here we present a scheme of nonreciprocal quantum state conversion between microwave and optical photons via an optomechanical interface. By introducing an auxiliary cavity and manipulating the phase differences between the linearized optomechanical couplings, uni-directional state transmission can be achieved. The interface can function as an isolator, a circulator, and a two-way switch that routes the input states to a selected output channel. We show that under a generalized impedance matching condition, the state conversion can reach high fidelity and is robust against the thermal fluctuations in the mechanical mode.

Vapor-grown carbon nanofiber/poly(ethylene-co-vinyl acetate) composites with electrical-active two-way shape memory behavior

Vapor-grown carbon nanofibers were filled into poly(ethylene-co-vinyl acetate) through solution mixing to achieve electrical-active two-way shape memory. The vapor-grown carbon nanofiber/poly(ethylene-co-vinyl acetate) nanocomposites were systematically and explicitly investigated through combined analytical techniques. Experimental results showed an increase in crystallization temperature ( Tc) and a decrease in melting temperature ( Tm) as the vapor-grown carbon nanofiber concentration in the nanocomposites increased. This result indicates that carbon nanofibers can act as nucleating agents during crystallization but may hinder the formation of thermodynamically stable crystals. The nanocomposites had a higher modulus but a lower strength than pure poly(ethylene-co-vinyl acetate). In two-way shape memory testing, a decrease in reversible strain and shape recovery occurred in the nanocomposites. Nevertheless, obvious two-way shape switching was observed in all samples during cyclic heating and cooling. The nanocomposite with 15% vapor-grown carbon nanofibers could be electrically heated rapidly and uniformly because of the high conductivity of vapor-grown carbon nanofibers and their uniform distribution in the matrix. Finally, the electrical-active two-way shape memory effect was achieved. This work contributes to the design of electrical-active two-way shape memory polymers in device applications for advanced functions.

Outage Analysis and Optimization of SWIPT in Network-Coded Two-Way Relay Networks

This paper investigates the outage performance of simultaneous wireless information and power transfer (SWIPT) in network-coded two-way relay systems, where a relay first harvests energy from the signals transmitted by two sources and then uses the harvested energy to forward the received information to the two sources. We consider two transmission protocols, power splitting two-way relay (PS-TWR) and time switching two-way relay (TS-TWR) protocols. We present two explicit expressions for the system outage probability of the two protocols and further derive approximate expressions for them in high and low SNR cases. To explore the system performance limits, two optimization problems are formulated to minimize the system outage probability. Since the problems are nonconvex and have no known solution methods, a genetic algorithm- (GA-) based algorithm is designed. Numerical and simulation results validate our theoretical analysis. It is shown that, by jointly optimizing the time assignment and SWIPT receiver parameters, a great performance gain can be achieved for both PS-TWR and TS-TWR. Moreover, the optimized PS-TWR always outperforms the optimized TS-TWR in terms of outage performance. Additionally, the effects of parameters including relay location and transmit powers are also discussed, which provide some insights for the SWIPT-enabled two-way relay networks.

Liquid-crystal order during synthesis affects main-chain liquid-crystal elastomer behavior.

This study presents the first direct comparison of the influence of liquid-crystal order during synthesis on the thermo-mechanical behaviors of main-chain liquid-crystal elastomers (LCEs) in thiol-acrylate networks. Six polydomain nematic elastomer (PNE) chemistries were compared directly by synthesizing with the mesogens in either an isotropic state (i-PNE) or a nematic state (n-PNE). The i-PNE networks were created in the presence of solvent, which disrupted any liquid-crystal order during network formation. Conversely, the n-PNE networks were created without the presence of solvent below the isotropic transition (TNI). Differential scanning calorimetry (DSC) was first performed, and it showed that i-PNE networks experienced a clearly defined nematic-to-isotropic transition upon heating, whereas the transition in n-PNE networks was unable to be identified, which may be the result of a nematic-to-paranematic phase transition. Dynamic mechanical analysis (DMA) tests revealed that while both networks maintained elevated loss tangent in the nematic region, only i-PNE networks prominently displayed dynamic soft elasticity behavior. The two-way shape switching behaviors of LCE networks were examined using actuation tests under a 100 kPa bias stress. It showed that the strain amplitude strongly depends on synthesis history; it ranges from 66% to 126% in i-PNE samples and 3% to 61% in n-PNE samples. To help interpret the different actuation strain behaviors between i-PNEs and n-PNEs, wide-angle X-ray scattering (WAXS) was then performed where the LCE samples were strained to 40%. The results showed that order parameter (S) in n-PNE samples (ranging from 0.37 to 0.50) is lower than that in i-PNE samples (0.54 for all cases), and the parameter decreased as the cross-linking density increased. The stress-strain behaviors of the LCE networks measured from uniaxial tension tests revealed that all i-PNE samples had a lower soft-elasticity plateau during loading compared to the n-PNE samples. Finally, free-standing strain recovery of LCE samples after being strained to 100% was investigated. Immediately after removing stress on the samples, i-PNE and n-PNE samples recovered 14% to 38% and 27% to 73% of strain, respectively. We discuss the advantages and disadvantages of the different synthetic histories on LCE design.

All oxide semiconductor-based bidirectional vertical p-n-p selectors for 3D stackable crossbar-array electronics.

Three-dimensional (3D) stackable memory devices including nano-scaled crossbar array are central for the realization of high-density non-volatile memory electronics. However, an essential sneak path issue affecting device performance in crossbar array remains a bottleneck and a grand challenge. Therefore, a suitable bidirectional selector as a two-way switch is required to facilitate a major breakthrough in the 3D crossbar array memory devices. Here, we show the excellent selectivity of all oxide p-/n-type semiconductor-based p-n-p open-based bipolar junction transistors as selectors in crossbar memory array. We report that bidirectional nonlinear characteristics of oxide p-n-p junctions can be highly enhanced by manipulating p-/n-type oxide semiconductor characteristics. We also propose an associated Zener tunneling mechanism that explains the unique features of our p-n-p selector. Our experimental findings are further extended to confirm the profound functionality of oxide p-n-p selectors integrated with several bipolar resistive switching memory elements working as storage nodes.

Operating principles of Notch–Delta–Jagged module of cell–cell communication

Notch pathway is an evolutionarily conserved cell–cell communication mechanism governing cell-fate during development and tumor progression. It is activated when Notch receptor of one cell binds to either of its ligand—Delta or Jagged—of another cell. Notch–Delta (ND) signaling forms a two-way switch, and two cells interacting via ND signaling adopt different fates—Sender (high ligand, low receptor) and Receiver (low ligand, high receptor). Notch–Delta–Jagged signaling (NDJ) behaves as a three-way switch and enables an additional fate—hybrid Sender/Receiver (S/R) (medium ligand, medium receptor). Here, by extending our framework of NDJ signaling for a two-cell system, we show that higher production rate of Jagged, but not that of Delta, expands the range of parameters for which both cells attain the hybrid S/R state. Conversely, glycosyltransferase Fringe and cis-inhibition reduces this range of conditions, and reduces the relative stability of the hybrid S/R state, thereby promoting cell-fate divergence and consequently lateral inhibition-based patterns. Lastly, soluble Jagged drives the cells to attain the hybrid S/R state, and soluble Delta drives them to be Receivers. We also discuss the critical role of hybrid S/R state in promoting cancer metastasis by enabling collective cell migration and expanding cancer stem cell (CSC) population.

A covering Ka-band two-way switch filter module using a three-line and anE-plane waveguide band-pass filters

A millimeter-wave ultrawideband two-way switch filter module is presented in this article. The switch filter module covers whole Ka-band (26–40 GHz), and is composed of two wideband band-pass filters and two monolithic microwave integrated circuit (MMIC) single pole two throw (SP2T) switches. One filter is realized using E-plane iris waveguide band-pass filter, and another is realized by a novel 11-pole three-line microstrip structure band-pass filter. Compared with the traditional three-line filter, the proposed three-line filter not only retains virtues of the traditional three-line filter, but also resolves drawbacks of it, which include discontinuities between adjacent sections, many parameters of design, and no effective matching circuits at input/output ports. The developed switch filter module is fabricated using hybrid integrated technology, which has a size of 51 × 26 × 9.8 mm3, and interconnections between MMICs and microstrip are established by bond wires. The fabricated switch filter module exhibits excellent performances: for two different states, the measured insertion loss and return loss are all better than 7 and 10 dB in each pass-band, respectively. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:305–310, 2015.

더블 빔 구조, 다파장 분석을 적용한 연속식 실시간 COD 측정 센서 개발

Abstract At present, the index of chemical oxygen demand (COD) is widely used as an indicator of organic water pollution with biochemicaloxygen demand (BOD). But, traditional COD measurement method are not only with various chemical reagents exhausted, but alsolong time consumed, the operation procedure and the modification are much professional. This paper reported a novel COD mea-surement system using double-beam and multiple wavelength analysis UV-VIS spectrometries. It consists of pulsed xenon lamp, two-way optical fiber, optical switch, spectrometer and main processor. Proposed COD measurement system obtains any spectral inform ationof water sample (KHP standard sample and two river water and wastewater) and reference sample (distilled water) in the range of200~520 nm, corresponding to the COD concentration from 0 to 300 mg/L through calculating the UV absorbance. The system showimproved precision and can work continuously fast at time interval about 25 seconds.Keywords: COD, Chemical oxygen demand, Absorption photometry, Double beam, Linear regression

Order reconstruction phenomena and temperature-driven dynamics in a 3D zenithally bistable device

We model the zenithally bistable device (ZBD) in three dimensions (3D), within the Landau-de Gennes theory, and find three stable static states in 3D without an applied field: the vertically aligned nematic (VAN) state, the hybrid aligned nematic (HAN) state and a third, high-tilt state, which we call the THAN state, with an interior and a surface defect. We recover the order reconstruction (OR) phenomenon around the defects in the HAN and THAN states and the 3D THAN and HAN solutions exhibit stable biaxial cylinders connecting defects on opposite faces of the ZBD device. We demonstrate a two-way temperature-driven switching between high-tilt and low-tilt states through controlled heating and cooling procedures in two dimensions (2D), with no applied fields.

PDGFRβ reverses EphB4 signaling in alveolar rhabdomyosarcoma.

Alveolar rhabdomyosarcoma (aRMS) is an aggressive myogenic childhood malignancy, not infrequently presenting as incurable metastatic disease. To identify therapeutic targets, we performed an unbiased tyrosine kinome RNA interference screen in primary cell cultures from a genetically engineered, conditional mouse model of aRMS. We identified ephrin receptor B4 (EphB4) as a target that is widely expressed in human aRMS and that portends a poor clinical outcome in an expression level-dependent manner. We also uncovered cross-talk of this ephrin receptor with another receptor tyrosine kinase, PDGFRβ, which facilitates PDGF ligand-dependent, ephrin ligand-independent activation of EphB4 converging on the Akt and Erk1/2 pathways. Conversely, EphB4 activation by its cognate ligand, EphrinB2, did not stimulate PDGFRβ; instead, apoptosis was paradoxically induced. Finally, we showed that small-molecule inhibition of both PDGFRβ and EphB4 by dasatinib resulted in a significant decrease in tumor cell viability in vitro, as well as decreased tumor growth rate and significantly prolonged survival in vivo. To our knowledge, these results are the first to identify EphB4 and its cross-talk with PDGFRβ as unexpected vital determinants of tumor cell survival in aRMS, with EphB4 at the crux of a bivalent signaling node that is either mitogenic or proapoptotic.

Light‐ and Redox‐Gated Molecular Brakes Consisting of a Pentiptycene Rotor and an Indole Pad

AbstractTwo photochemically and electrochemically active alkenes 3Me and 3An containing pentiptycene and indole groups have been synthesized and investigated as light and/or redox‐gated molecular brakes. The pentiptycene group functions as the four‐bladed rotor, the indole group as the brake pad, and the vinylene group as the switch module. The E configuration corresponds to the brake‐off state, in which the rotation of the rotor is free with a rotation rate of 108‐109 at ambient temperature according to DFT calculations. The Z configuration corresponds to the brake‐on state, in which the rotation rate is decreased to 101‐102, depending on the N‐substituent of indole, according to line‐shape analysis of variable temperature 13C NMR spectra. The overall braking effect reaches a factor of 106‐108. While the combined photochemical E → Z and electrochemical Z → E switching has a higher capacity than the two‐way photochemical switching in the case of 3Me, the switching capacity are comparable for the two methods in 3An. The results also show that photochemical E‐Z isomerization is much more reliable than the electrochemical counterpart, as the stability of the redox intermediates plays a critical role in determining the robustness of the molecular brakes via electrochemical switching.

Moonlighting cell-surface GAPDH recruits apotransferrin to effect iron egress from mammalian cells.

Iron (Fe(2+), Fe(3+)) homeostasis is a tightly regulated process, involving precise control of iron influx and egress from cells. Although the mechanisms of its import into cells by iron carrier molecules are well characterized, iron export remains poorly understood. The current paradigm envisages unique functions associated with specialized macromolecules for its cellular import (transferrin receptors) or export (ferroportin, also known as SLC40A1). Previous studies have revealed that iron-depleted cells recruit glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a multitasking, 'moonlighting' protein, to their surface for internalization of the iron carrier holotransferrin. Here, we report that under the converse condition of intracellular iron excess, cells switch the isoform of GAPDH on their surface to one that now recruits iron-free apotransferrin in close association with ferroportin to facilitate the efflux of iron. Increased expression of surface GAPDH correlated with increased apotransferrin binding and enhanced iron export from cells, a capability lost in GAPDH-knockdown cells. These findings were confirmed in vivo utilizing a rodent model of iron overload. Besides identifying for the first time an apotransferrin receptor, our work uncovers the two-way switching of multifunctional molecules to manage cellular micronutrient requirements.

A plasma-treated chalcogenide switch device for stackable scalable 3D nanoscale memory

Stackable select devices such as the oxide p-n junction diode and the Schottky diode (one-way switch) have been proposed for non-volatile unipolar resistive switching devices; however, bidirectional select devices (or two-way switch) need to be developed for bipolar resistive switching devices. Here we report on a fully stackable switching device that solves several problems including current density, temperature stability, cycling endurance and cycle distribution. We demonstrate that the threshold switching device based on As-Ge-Te-Si material significantly improves cycling endurance performance by reactive nitrogen deposition and nitrogen plasma hardening. Formation of the thin Si₃N₄ glass layer by the plasma treatment retards tellurium diffusion during cycling. Scalability of threshold switching devices is measured down to 30 nm scale with extremely fast switching speed of ~2 ns.