Distinct Switching Research Articles

Human Perifollicular Macrophages Undergo Apoptosis, Express Wnt Ligands, and Switch their Polarization during Catagen

Human Perifollicular Macrophages Undergo Apoptosis, Express Wnt Ligands, and Switch their Polarization during Catagen

Practical frequency-domain characterization of switching converters under PWM via Floquet theory

This paper presents the application of a frequency-domain characterization approach applicable to modern power systems involving distinct switching converters via Floquet transformation. As main feature, Floquet theory permits to characterize a network involving switching converters in terms of poles location in the complex plane. This feature can be utilized as an auxiliary tool for parameter design and for stability assessment of a switched network, especially in closed-loop operation. The paper shows that Floquet theory is readily applicable to pulse-width modulation schemes employed in modern electrical networks. Two switched networks, i.e., an HVDC system and a grid-tied system of three photovoltaic generators, are presented as case studies to support the statements above.

Light Driven Active Transition of Switching Modes in Homogeneous Oxides/Graphene Heterostructure.

Depending on the mobile species involved in the resistive switching process, redox random access memories and conductive bridge random access memories are widely studied with distinct switching mechanisms. Although the two resistance switching types have faithfully proved to be electrochemically linked in metal oxide‐based memristive devices, the corresponding photo‐induced transition has not yet been realized. Here, a photo‐induced transition through the integration of a graphene layer into a titanium oxide‐based memory device is demonstrated. Coupled with Raman mapping and an electron energy loss spectroscopy technique, the photo‐induced interaction at the heterostructure of graphene/titanium oxide are considered to dominate the transition process. Moreover, a negative differential resistance effect is observed by controlling the applied voltage, which can be credited to the saturation of trap centers (oxygen vacancies) and the increase of interfacial barrier at the graphene/titanium oxide heterojunction.

All-Solid-State Synaptic Transistors with High-Temperature Stability Using Proton Pump Gating of Strongly Correlated Materials.

Designing energy-efficient artificial synapses with adaptive and programmable electronic signals is essential to effectively mimic synaptic functions for brain-inspired computing systems. Here, we report all-solid-state three-terminal artificial synapses that exploit proton-doped metal-insulator transition in a correlated oxide NdNiO3 (NNO) channel by proton (H+) injection/extraction in response to gate voltage. Gate voltage reversibly controls the H+ concentration in the NNO channel with facile H+ transport from a H+-containing porous silica electrolyte. Gate-induced H+ intercalation in the NNO gives rise to nonvolatile multilevel analogue states due to H+-induced conductance modulation, accompanied by significant modulation of the out-of-plane lattice parameters. This correlated transistor operated by a proton pump shows synaptic characteristics such as long-term potentiation and depression, with nonvolatile and distinct multilevel conductance switching by a low voltage pulse (≥ 50 mV), with high energy efficiency (∼1 pJ) and tolerance to heat (≤150 °C). These results will guide the development of scalable, thermally-stable solid-state electronic synapses that operate at low voltage.

Above Room Temperature Reversible Phase Transition Induces Distinct Dielectric and Nonlinear Optical Switching Response Behavior in Crown-Ether-Based Supramolecular Clathrate

Stimuli-responsive materials with coexisting nonlinear optical (NLO) and dielectric properties are technologically important, which enable simultaneous conversion of optoelectronic properties between different states under external stimuli. By rationally screening guest cations (C6H5NF2)+ in the crown-ether inclusion system, we synthesized a crown-ether supramolecular compound [(C6H5NF2)(18-crown-6)][PF6] (1). Differential scanning calorimetry (DSC) showed that 1 undergoes a reversible phase transition above room temperatures (305 K/292 K), with a thermal hysteresis of 13 K. Temperature-dependent dielectric and NLO measurements show that the compound exhibits two distinct switching response behaviors. Structural analysis indicates that the order–disorder change of the host molecule 18-crown-6 and the guest organic cation during the phase transition induces the dielectric and NLO switching behavior of the compound.

Identification of regulatory elements recapitulating early expression of L-plastin in the zebrafish enveloping layer and embryonic periderm

We have cloned and characterized an intronic fragment of zebrafish lymphocyte cytosolic protein 1 (lcp1, also called L-plastin) that drives expression to the zebrafish enveloping layer (EVL). L-plastin is a calcium-dependent actin-bundling protein belonging to the plastin/fimbrin family of proteins, and is necessary for the proper migration and attachment of several adult cell types, including leukocytes and osteoclasts. However, in zebrafish lcp1 is abundantly expressed much earlier, during differentiation of the EVL. The cells of this epithelial layer migrate collectively, spreading vegetally over the yolk. L-plastin expression persists into the larval periderm, a transient epithelial tissue that forms the first larval skin. This finding establishes that L-plastin is activated in two different embryonic waves, with a distinct regulatory switch between the early EVL and the later leukocyte. To better study L-plastin expressing cells we attempted CRISPR/Cas9 homology-driven recombination (HDR) to insert a self-cleaving peptide (Cre-P2A-EGFP-CAAX) downstream of the native lcp1 promoter. This produced a stable zebrafish line expressing Cre recombinase in EVL nuclei and green fluorescence in EVL cell membranes. In vivo tracking of these labeled cells provided enhanced views of EVL migration behavior, membrane extensions, and mitotic events. Finally, we experimentally dissected key elements of the targeted lcp1 locus, discovering a ∼300 bp intronic sequence sufficient to drive EVL expression. The lcp1: Cre-P2A-EGFP-CAAX zebrafish should be useful for studying enveloping layer specification, gastrulation movements and periderm development in this widely used vertebrate model. In addition, the conserved regulatory sequences we have isolated predict that L-plastin orthologs may have a similar early expression pattern in other vertebrate embryos.

Kinetic control of tunable multi-state switching in ferroelectric thin films

Deterministic creation of multiple ferroelectric states with intermediate values of polarization remains challenging due to the inherent bi-stability of ferroelectric switching. Here we show the ability to select any desired intermediate polarization value via control of the switching pathway in (111)-oriented PbZr0.2Ti0.8O3 films. Such switching phenomena are driven by kinetic control of the volume fraction of two geometrically different domain structures which are generated by two distinct switching pathways: one direct, bipolar-like switching and another multi-step switching process with the formation of a thermodynamically-stable intermediate twinning structure. Such control of switching pathways is enabled by the competition between elastic and electrostatic energies which favors different types of ferroelastic switching that can occur. Overall, our work demonstrates an alternative approach that transcends the inherent bi-stability of ferroelectrics to create non-volatile, deterministic, and repeatedly obtainable multi-state polarization without compromising other important properties, and holds promise for non-volatile multi-state functional applications.

Two new transformerless high step‐down DC–DC converters

In this study, two new high step-down DC–DC converters are proposed. The proposed converters are designed transformerless and have similar power circuits. For controlling the switches of the proposed converters, two distinct switching patterns are applied. The first switching pattern is interleaved pulse-width modulation pulses with 180° phase shifts, which are applied for the first proposed converter, therefore, the first converter has an interleaved switching pattern and its structure is symmetrical, the voltage stress on its elements decreased. On the other hand, there will be two conversion ratio equations for the first proposed converter for duty cycles larger and less than 0.5. The second switching pattern is applied to the proposed second converter; therefore, in this case, the constant voltage gain is obtained for the whole ranges of duty cycles. The sum of voltage stress on its switches and diodes are a little more than the first converter. The proposed converters are analysed for all of their operating modes. To verify the theoretical results, a prototype of the first and second proposed converter for 500/26 and 800/20.5 V, respectively, and 430 W is implemented in laboratory and the extracted results are compared with calculated ones.

Investigating the Mode Switching Behavior from Different Non-Car Modes to Car: The Role of Life Course Events and Policy Opportunities

Life course events can lead to a habitual change of mode choice, which can sometimes be from non-car modes to the car, which is not a desirable outcome from a sustainable point of view. This research studied in depth the mode switching behavior from a range of non-car modes to the car, to identify opportunities for policy intervention to hold back such changes in habit toward car usage. Retrospective commute mode choice and various life course event data over four observation periods were collected. A mixed binary logit regression model was developed to study mode switching behavior from car to non-car modes, followed by the development of a set of “mirror models” (also mixed binary logit) that evaluated mode switches from non-car modes to the car. By observing their distinct reactions to life course events, it was found that users of different types of non-car modes display distinct mode switching behavior, especially in relation to getting married, having their first child and in response to different degrees of commute distance change. A thorough discussion on the policy implications of these findings is provided.

A Dual-Channel Magnetically Integrated EV Chargers Based on Double-Stator-Winding Permanent-Magnet Synchronous Machines

In this paper, a dual-channel isolated magnetically integrated charger is proposed for electric vehicles (EVs). The key is to apply and operate two interleaved power charging channels, each of which is composed of one dual-active-bridge isolated converter and one voltage-source inverter. The proposed configuration not only offers electric isolation under charging operation but also provides modular design and operation for each power conversion channel. By integrating the grid inductances with the double-stator-winding permanent-magnet (PM) synchronous machine under charging operation, the volume and weight of the charging system are saved for EVs. By reconfiguration of power circuits, the proposed dual-channel magnetically integrated EV chargers can be used for both single-phase and three-phase charging operations. The mechanical vibration caused by interaction between grid currents and PM flux can be mitigated by using the dual-channel charging operation. The interleaved operation and the phase-shifted modulation have been proposed for the dual charging channels to offer low current ripple on battery side and better harmonic performance on grid side. Furthermore, chaotic modulation strategies have been proposed to reduce the distinct switching harmonics in spectrum, which will facilitate improving the conducted electromagnetic compatibility in EVs. The experiments have been carried out on a 1-kW laboratory prototype to verify the validity of the proposed schemes.

Absence of Cytosolic 2-Cys Prx Subtypes I and II Exacerbates TNF-α-Induced Apoptosis via Different Routes

There are abundant peroxiredoxin (Prx) enzymes, but an increase of cellular H2O2 level always happens inapoptotic cells. Here, we show that cellular H2O2 switches different apoptosis pathways depending on which type of Prx enzyme is absent. TNF-α-induced H2O2 burst preferentially activates the DNA damage-dependent apoptosis pathway in the absence of PrxI. By contrast, the same H2O2 burst stimulates the RIPK1-dependent apoptosis pathway in the absence of PrxII by inducing the destruction of cIAP1 in caveolar membrane. Specifically, H2O2 induces the oxidation of Cys308 residue in the cIAP1-BIR3 domain, which induces the dimerization-dependent E3 ligase activation. Thus, the reduction in cIAP level by the absence of PrxII triggers cell-autonomous apoptosis in cancer cells and tumors. Such differential functions of PrxI and PrxII are mediated by interaction with H2AX and cIAP1, respectively. Collectively, this study reveals the distinct switch roles of 2-Cys Prx isoforms in apoptosis signaling.

Spin\u2013orbit torque switching in a T-type magnetic configuration with current orthogonal to easy axes

Different symmetry breaking ways determine various magnetization switching modes driven by spin–orbit torques (SOT). For instance, an applied or effective field parallel to applied current is indispensable to switch magnetization with perpendicular anisotropy by SOT. Besides of this mode, here we experimentally demonstrate a distinct field-free switching mode in a T-type magnetic system with structure of MgO/CoFeB/Ta/CoFeB/MgO where a perpendicular layer with tilted easy axis was coupled to an in-plane layer with a uniaxial easy axis. Current was applied orthogonal to both easy axes and thus also normal to an in-plane effective field experienced by the perpendicular layer. Dynamic calculation shows perpendicular layer could be switched at the same time as the in-plane layer is switched. These field-free switching modes realized in the same T-type magnetic system might expedite the birth of multi-state spin memories or spin logic devices which could be operated by all electric manners.

Coded Switching Scheme for Monitoring the Operation of Distribution Capacitors

A novel scheme is proposed to monitor the operation of capacitors scattered in MV distribution systems. It first codes each capacitor with a distinctive switching character by setting a unique combination of a three-phase switching order and time interval. As a result, the transient of the three-phase reactive power during capacitor switching will appear in a unique way. Then, the reactive power disturbances monitored in the substation are decoded to identify which capacitor is being switched on and off . A detailed decoding method is developed to realize this identification without being impacted by the switching interference of loads and other reactive power compensation devices. Moreover, the implementation of the proposed scheme in the field is elaborated, and the resultant three-phase voltage unbalance is analyzed in this paper. Compared with existing methods, this scheme only requires one power quality monitor located at the substation to monitor the operations (energizing or de-energizing) of downstream distribution capacitors without extra communication devices. The operation information is valuable for tackling power quality problems caused by capacitor switching and optimizing the distribution grid operation.

Abstract 16647: Loss of Reversibility in Flow-Induced Pulmonary Arterial Hypertension is Associated With a Senescent Vascular Phenotype and Can Be Rescued by Targeted Senolysis

Introduction: Patients with congenital heart disease (CHD) are at risk of developing progressive pulmonary arterial hypertension (PAH). Timely hemodynamic unloading (HU) by surgical shunt correction usually reverses the arteriopathy, but the timepoint when or reason why PAH becomes irreversible remains elusive. Methods: PAH was created in syngeneic rats by monocrotalin (MCT) injection and an aorto-caval shunt. For HU at different PAH stages, the left donor lung with PAH was transplanted into healthy recipients at t14/t21/t28. Recipients were sacrificed 21days after transplantation. Results: MCT+Shunt induced medial neomuscularization from t14, and neointimal lesions from t21, causing arteriolar occlusion and PAH. HU normalized the vascular morphology in all t14 rats and in 7/10 t21 rats, whereas no reversal or progressive occlusion occurred in 3/10 t21 and all t28 rats. RNA-sequencing revealed that activated pro-proliferative/regenerative, pro-apoptotic and DNA-repair pathways were associated with reversal after HU. This was confirmed immunohistochemically by increased vascular-specific Ki67, Caspase3 and Rad51 protein expression. In contrast, irreversibility was associated with deactivation of latter pathways and activated pro-survival, pro-senescence and pro-inflammatory pathways, as confirmed by increased Survivin, p16 ink4A , p21 cip1 , TNFα, IL6 and MMP2. These findings were also confirmed in human PAH-CHD explant tissue. Finally, we report that the senolytic BCL2 antagonist ABT263 selectively targets rat endothelial cells made senescent by irradiation. Moreover, low-dose ABT263 treatment from t25 to t32 in MCT+Shunt rats significantly improved pulmonary hemodynamics and relieved PAH symptoms. Conclusions: Similar to clinical observations in PAH-CHD, this study showed that HU reverses PAH only in an early stage, and describes a zone of no return. We characterized the mechanistic basis for (loss of) reversibility, showing a distinct switch from increased proliferation/regeneration, apoptosis and DNA-repair, to a growth arrested, apoptosis-resistant and intrinsically pro-inflammatory phenotype, suggesting a role for senescence. Reversal of this phenotype by targeted senolysis also reversed PAH beyond the zone of no return.

Exploring Controls on Rainfall‐Runoff Events: 1. Time Series‐Based Event Separation and Temporal Dynamics of Event Runoff Response in Germany

AbstractAnalyzing a response of catchments to rainfall inputs allows for deeper insights on the mechanisms of runoff generation at catchment scale. In this study an automated time series‐based event separation procedure consisting of available base flow separation, runoff event identification, and rainfall attribution methods and of a novel iterative procedure for the adjustment of thresholds used to identify single‐peak components of multiple‐peak events is proposed. Event runoff coefficient, time scale, rise time, and peak discharge of more than 220,000 identified rainfall‐runoff events are then used to analyze dynamics of event runoff response in 185 catchments at multiple temporal scales. In mountainous catchments with poor storage event runoff response is strongly controlled by the characteristics of rainfall and is generated by event‐fed saturation or infiltration excess. A distinct switch between saturated and unsaturated states occurs in these catchments. A weak relation between rainfall and runoff event properties is instead observed in lowland and hilly catchments with substantial storage, where a gradual transformation between functioning states occurs and the response is driven by preevent saturation. The seasonality of their event characteristics is governed by the contribution of snowmelt and the seasonality of the aridity index rather than of rainfall properties. Long‐term changes of total precipitation amount alone do not explain season‐specific long‐term changes of event characteristics that are rather consistent with changes of seasonal indicators of the wetness state. The effects of land use changes are detectable only in a few cases and display themselves mostly in the characteristic response time of catchments.

Urban Identities and Belonging: Young Men’s Discourses about Pikine (Senegal)

Suburbs in many parts of the world fall victim to discriminating assessments from the outside. Pikine, an urban area within the Dakar region of Senegal, which was one of urban Africa’s major government restructuring projects, is no exception. The frequently evoked and generalised narratives of urban lifeworlds often fail to describe the heterogeneous characteristics of neighbourhoods in precarious large agglomerations throughout the world. In particular, the youth in this urban quarter are important drivers of economic growth and means with which to combat poverty and strengthen social cohesion. This chapter, based on 11 months of ethnographic fieldwork in Pikine between 2011 and 2013, will illustrate how resourceful young men organise their lives. On the one hand, they have equipped themselves with distinct identities and switch them depending on the situation. On the other hand, they have resurrected their feelings of solidarity, courage and local pride in the notion of Pikinité as a ‘self-revaluation-standard’. Because of increasingly precarious realities and rising unemployment, individualistic tendencies—combined with the aspiration of self-realisation—have gained ground and challenge these stratagems.

Reversible photoswitching of encapsulated azobenzenes in water

Efficient molecular switching in confined spaces is critical for the successful development of artificial molecular machines. However, molecular switching events often entail large structural changes and therefore require conformational freedom, which is typically limited under confinement conditions. Here, we investigated the behavior of azobenzene-the key building block of light-controlled molecular machines-in a confined environment that is flexible and can adapt its shape to that of the bound guest. To this end, we encapsulated several structurally diverse azobenzenes within the cavity of a flexible, water-soluble coordination cage, and investigated their light-responsive behavior. Using UV/Vis absorption spectroscopy and a combination of NMR methods, we showed that each of the encapsulated azobenzenes exhibited distinct switching properties. An azobenzene forming a 1:1 host-guest inclusion complex could be efficiently photoisomerized in a reversible fashion. In contrast, successful switching in inclusion complexes incorporating two azobenzene guests was dependent on the availability of free cages in the system, and it involved reversible trafficking of azobenzene between the cages. In the absence of extra cages, photoswitching was either suppressed or it involved expulsion of azobenzene from the cage and consequently its precipitation from the solution. This finding was utilized to develop an information storage medium in which messages could be written and erased in a reversible fashion using light.

Monolayer microgel composite membranes with tunable permeability

Membranes with tunable gating functionality can be produced by modification with thermo-responsive polymers and colloids. We propose a straightforward method to gain this responsiveness by adsorption of microgels to the membrane surface. To be able to predict the filtration properties of the resulting composite membrane, a comprehensive understanding of the behavior of adsorbed microgels on porous substrates under convective flow is required. Previous studies focus on constant pressure experiments at various temperatures neglecting changes in viscosity and flux. In this study, we investigate the permeability and selectivity of poly-n-isopropyl-acrylamide (PNIPAM) monolayer microgel membranes under convective flow in cross-flow mode applying a constant flux. We use in-situ spectroscopic ellipsometry on a porous substrate to prove a reproducible and confluent monolayer microgel deposition. Supporting scanning electron micrographs and confocal laser scanning micrographs confirm the high reliability of the ellipsometry data set.The monolayer microgel membranes show distinct switching between 25 and 50 °C. When increasing the temperature above the microgel's volume phase transition temperature, the molecular weight cut-off (MWCO) of the functionalized membrane shifts to lower molar masses controlling the dextran retention between 30% and 70% only when the pore size of the support is in an appropriate range. The confluent monolayers are also mechanically stable when backwashed. Our data give insight into the responsive behavior of the PNIPAM network under convective flow – a key issue for custom-made filtration tasks.

Aligned P(VDF-TrFE) Nanofibers for Enhanced Piezoelectric Directional Strain Sensing.

Piezoelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) nanofibers fabricated by electrospinning have drawn increasing levels of attention in the fields of flexible sensors and nanogenerators. However, the directional dependence of piezoelectricity of electrospun nanofibers remains elusive. In this study, the piezoelectric performances of individual nanofibers are characterized by piezoresponse force microscopy (PFM), while the effects of annealing on β-phase crystallinities are investigated by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The experimental results reveal that the as-spun P(VDF-TrFE) nanofibers form higher content of β-phase compared with spin-coated films, and the content of β-phase increases by annealing. The annealed P(VDF-TrFE) nanofiber exhibits distinct vertical polarization switching characteristics. The high piezoelectric output in the thickness direction and low piezoelectric output in the longitudinal direction of the nanofiber mats further confirm that the preferential dipole orientation of electrospun P(VDF-TrFE) nanofibers is normal to the surface of the substrate. Highly aligned P(VDF-TrFE) nanofibers show directional strain sensing ability due to the piezoelectric and mechanical anisotropy.

Will they pitch or will they switch? Comparing Chinese and American consumers

AbstractThis study compares the conditions for consumer satisfaction and word of mouth (WOM) between Chinese and American consumers. The authors utilize a between‐subjects factorial design experiment to investigate the effect of service experience (positive or negative) and consumption context (hedonic vs. utilitarian) across these two cultures. Results indicate that consumers perceive higher levels of satisfaction and switching costs, and provide higher WOM intention for positive than for negative service experiences. The relationship between service experience and perceived switching costs is further moderated by consumption context and culture. Of importance is the critical mediating role of consumer satisfaction in driving perceived switching costs and WOM intention. The comparison of Chinese and American consumers also reveals the distinct switching behaviors between the two groups of consumers, which can be explained from a cultural perspective. The study findings provide insights into provider‐switching and WOM‐spreading behaviors by Chinese and American consumers, under hedonic versus utilitarian consumption contexts.