Bidirectional Transfer Research Articles

Coupling multifunctional catalytic active sites into metal carbide catalysts to promote the multipath bidirectional conversion of Li-S redox

Li-S batteries are hampered by sluggish liquidsolid redox and shuttle effects. Herein, a strategy of coupling multifunctional catalytic sites is proposed to fabricate bidirectional catalysts to promote multipath bidirectional Li-S redox conversion. By engineering Co or Zr dopants into Ni3C/C, the obtained Co0.30Ni2.70C/C and Zr0.30Ni2.70C/C electrocatalysts play different roles in polysulfide adsorption and multipath bidirectional conversion. During the discharging/charging process, due to limited electron transfer between the Co3+/Co2+ pair and polysulfides, Co sites themselves are catalytically inactive for the conversion of polysulfides and only act as promoters to improve the catalytic activity of Ni sites. In contrast, in addition to being promoters, Zr sites serve as electron acceptors and donors to catalyze bidirectional Li-S redox due to the flexible electron transfer between the Zr4+/Zr2+ pair and polysulfides. Such bidirectional electron transfer is accompanied by thiosulfate-mediated redox. Therefore, Zr doping not only accelerates the inherent solid (S8)-liquid (polysulfide)-solid (Li2S) conversion pathway but also propels the reversible thiosulfate-mediated conversion pathway. As a result, when the Zr0.30Ni2.70C/C nanosheets were used to modify the commercial PP separator, the Li-S batteries exhibit improved electrochemical performance (a decay of 0.0756 % over 200 cycles with a sulfur loading of 5.0 mgs cm−2).

Water transport through the inward combined carbon nanotube

The structure of the carbon nanotube affects water transport greatly. However, there is little understanding of water transport through the inward combined carbon nanotube. Molecular dynamics simulations are adopted to investigate the properties of water molecules through the inward combined carbon nanotube in this article. We find that water unidirectional transport efficiency increases in the inward combined carbon nanotube unless water molecules cannot pass through the inward combined carbon nanotube. The occupancy of water molecules, the bidirectional water transfer rate, the unidirectional water transfer rate, the velocity, and the order parameter of water molecules in the inward carbon nanotube are dependent on the structure of the inward combined carbon nanotube. Our results pave the way for understanding the inward combined structure effect on the transport of water molecules.

Modular Multilevel Matrix Converter as Solid State Transformer for Medium and High Voltage AC Substations

The use of power converters as solid state transformers is an attractive solution to modernize the power network, but this solution has not been fully addressed for MV and HV substations. This paper presents a customized and simple control for the Modular Multilevel Matrix Converter (M3C), specially conceived for its operation on synchronous ports, which is the case of AC substations. The control allows bidirectional power transfer, generation/absorption of reactive power and provisions of ancillary services. The converter is compared to the back-to-back Modular Multilevel Converter (B2B-MMC) where the key performance indicators to carry out the comparison are power efficiency, number of semiconductor devices, passive components required, footprint, voltage cell balance, fault blocking capability and stress of components. The simulation results show the features, performance and attractiveness of the M3C topology in a 33/11 kV, 16 MW substation under different operating conditions, including grid faults and dynamic operation. The M3C presents similar efficiency and performance than the B2B-MMC, but it uses fewer semiconductor devices, passive components and total cell capacitor energy than the B2B-MMC, reducing cost and footprint. The experimental results show the performance of the M3C under less ideal conditions including a substation transformer saturation and power step response.

Assisted Power Transfer for Voltage Balance of Bipolar DC MicroGrids Using Inactive Motor Drives

A voltage balancer remains a good solution of power transfer for bipolar dc grids, which, however, would increase the costs due to its requirement for additional hardware support. In this article, an auxiliary power transfer strategy is proposed by using the inactive motor drives affiliated with the bipolar dc grid. During idle periods of the motor drive, one inverter bridge arm is connected with the bipolar dc grid at their neutral points, allowing bidirectional power transfer between the upper and lower dc-bus sources. The proposed strategy share part of the voltage balancer's power transfer burden without requiring additional hardware and affecting the normal operations of the motor drive. In addition, its effectiveness is verified by experimental results on an interior permanent magnet synchronous motor drive, showing that the power flows among the upper and lower dc-bus power supplies are controlled effectively. Also, the active control of the dc-bus voltages could be achieved by modulation of the phase currents.

Application of Blockchain for Secure Data Transmission in Distributed State Estimation

The application of renewable energy sources in the power grid increases the necessity of tracking the system state, especially in smart grids, where there is a bidirectional transfer of data and power. The complexity of coupling between communication and the electrical infrastructure in a smart grid increases the risk of security breaches. Increasing the state estimation accuracy helps the smart grid operator efficiently manage the system. This article proposes an integration of distributed state estimation with a blockchain-designed communication platform. Additionally, the asynchronous data transmission, which is more likely to happen in the real world, is considered as the second task of this research. Finally, a detailed analysis of the blockchain-based application in distributed state estimation is provided. The numerical analysis shows that the proposed method meets real-world performance requirements and brings high security and reliability to the distributed state estimation process.

Kinetics of DNA strand transfer between polymerase and proofreading exonuclease active sites regulates error correction during high-fidelity replication

We show that T7 DNA polymerase (pol) and exonuclease (exo) domains contribute to selective error correction during DNA replication by regulating bidirectional strand transfer between the two active sites. To explore the kinetic basis for selective removal of mismatches, we used a fluorescent cytosine analog (1,3-diaza-2-oxophenoxazine) to monitor the kinetics of DNA transfer between the exo and pol sites. We globally fit stopped-flow fluorescence and base excision kinetic data and compared results obtained with ssDNA versus duplex DNA to resolve how DNA transfer governs exo specificity. We performed parallel studies using hydrolysis-resistant phosphorothioate oligonucleotides to monitor DNA transfer to the exo site without hydrolysis. ssDNA binds to the exo site at the diffusion limit (109M-1 s-1, Kd = 40 nM) followed by fast hydrolysis of the 3'-terminal nucleotide (>5000s-1). Analysis using duplex DNA with a 3'-terminal mismatch or a buried mismatch exposed a unique intermediate state between pol and exo active sites and revealed that transfer via the intermediate to the exo site is stimulated by free nucleoside triphosphates. Transfer from the exo site back to the pol site after cleavage is fast and efficient. We propose a model to explain why buried mismatches are removed faster than single 3'-terminal mismatches and thereby provide an additional opportunity for error correction. Our data provide the first comprehensive model to explain how DNA transfer from pol to exo active sites and back again after base excision allow efficient selective mismatch removal during DNA replication to improve fidelity by more than 1000-fold.

Structure evolution and performance of poly (vinyl alcohol) fibers with controllable cross-section fabricated using a combination of melt-spinning and stretching

Profiled fibers are gained potential applications in the fields of both functional textiles and cements reinforcements. While the commercial Poly (vinyl alcohol) (PVA) fibers are generally produced by solution spinning, which is difficult to prepare profiled PVA fiber with controllable cross-section because of bidirectional mass transfer in coagulation bath. In this work, based on intermolecular complexation and plasticization, water was adopted to improve the thermal-processing of PVA, the special-shaped PVA fibers such as triangular, trilobal, cruciform and wavy cross-sections were prepared by melt-spinning. The crystallinity of profiled as-spun PVA fibers was lower than 32%, and their elongation at break was higher than 400%, resulting in good stretch-ability for hot-drawing. During the hot-drawing of profiled PVA fibers, the circular trend of the characteristic sections can be controlled, and the reduction in profile degree was lower than 9.4%. Hot-drawing improved the crystalline structure of PVA, and increased the crystallinity, orientation, tensile strength, and melting point of profiled fibers. When the draw ratio was 9, the tensile strength of triangular, cruciform, trilobal and wavy fibers were 585 MPa, 559 MPa, 481 MPa and 585 MPa, respectively, which proposed a new processing technology of special-shaped PVA fiber and enriched the kinds of special-shaped fibers.

Steering bi-directional charge transfer via non-conjugated insulating polymer

Exquisite tuning of spatial charge transfer and separation has been an enduringly core issue in heterogeneous photocatalysis. Nevertheless, precise modulation of directional charge transfer to the ideal catalytically active sites remains challenging owing to rapid recombination rate of photoinduced charge carriers and sluggish charge transfer kinetics. Herein, bi-directional spatially separated electron and hole transport channels were simultaneously constructed over transition metal chalcogenides (TMCs)-based heterostructures via an efficient and facile electrostatic self-assembly strategy. Tailor-made positively charged non-conjugated polymer of branched polyethyleneimine (BPEI) and negatively charged metal nanocrystals (NCs) building blocks were controllably anchored on the TMCs substrate. We found that electrons photoexcited over TMCs substrate can migrate spontaneously, smoothly and unidirectionally to the tightly integrated neighboring metal NCs, wherein metal NCs function as Schottky-type electron-trapping reservoirs and the ultra-thin intermediate BPEI layer serves as a directional hole transport mediator, thus synergistically contributing to the significantly enhanced charge separation and prolonged charge lifetime. Benefiting from these merits, such self-assembled TMC@BPEI/metal heterostructure exhibits the markedly enhanced photoreduction catalysis toward photocatalytic hydrogen generation and anaerobic selective reduction of nitroaromatics to amino derivatives under visible light irradiation. Our work would provide inspiring idea for fine modulation of charge separation and transfer toward solar-to-chemical energy conversion.

Lateral dynamics of a monopile partially embedded in layered saturated soil with radial disturbance

A bidirectional transfer matrix method is presented to investigate the impedances of a laterally loaded monopile partially embedded in layered saturated soil with radial disturbance. To characterize the radial variation of soil properties induced by construction excitations or cyclic lateral excitations, the radial transfer matrix of the saturated soil is developed to determine the horizontal resistance of soil to the pile shaft based on Biot's theory. Lateral, rocking and lateral-rocking coupled impedances at the head of the monopile are obtained by solving the differential equations for transverse vibration of the pile shaft based on the Timoshenko beam theory, combined with an axial transfer matrix to treat the layered property of soil along the partially embedded monopile. The proposed model is validated by comparing it with some existing results. The theoretical rigour and broad engineering applicability of the present model are highlighted by a series of parametric analyses for the influences of soil and pile properties on the impedances of the laterally loaded monopile.

Wireless Power and Bidirectional Data Transfer System for IoT and Mobile Devices

Wireless power and bidirectional wireless data transfer system using a conventional 2-coil inductive link is presented for Internet-of-Things (IoT) and mobile applications without any additional coil or antenna. The proposed system utilizes the dual-band frequency shift-keying and the load shift-keying for the downlink and uplink telemetries, respectively, while ∼140 mW power is delivered to the receiver in the 2-coil inductive link. The data rates for downlink and uplink telemetries are 800 kb/s and 14 kb/s with 3.12 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−5</sup> and <10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−6</sup> bit error rate at 10 mm distance, respectively.

Asymmetric Bidirectional Capacitive Power Transfer Method With Push–Pull Full-Bridge Hybrid Topology

Bidirectional capacitive power transfer technology makes it possible for energy sharing among multiple electronic devices. This article proposes an asymmetrical bidirectional power conversion topology to satisfy different input and output characteristics’ requirements and increase load variation tolerance. A π–T ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLC</i> – <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> ) resonant topology is designed for this bidirectional conversion mode with constant output voltage characteristics in both directions. A hybrid power flow regulation strategy is proposed by integrating multiple zero-voltage switching soft-switching operating points switching and phase-shifted mode. This method overcomes the problem of mixing two different type topologies (push–pull and full bridge) with two different power regulation modes (switch soft-switching operating points and phase shift), which provide a way to make two different chargers compatible. Simulation and experimental results verified the proposed method.

Optimal Design of Resonant Network for Resonant Converter

The dc transformer based on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLLC</i> resonant converter is widely researched in the dc microgrid due to its excellent bidirectional power transfer capacity. Many resonant network design methods assume that the resonant current is constant during the deadtime. It may lead to hard switching or large conduction loss. Besides, the effects of deadtime on soft switching have not been closely analyzed. This article proposes an optimized design method to minimize conduction losses while achieving zero voltage switching, and it can easily obtain the optimal region and deadtime selection range. Parametric design and deadtime selection principles are derived based on the time-domain models, and then the design method and corresponding procedure are developed. Finally, a 4-kW 500-kHz <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLLC</i> resonant converter prototype is built to verify the feasibility of the proposed optimal design method.

Exploiting high-order behaviour patterns for cross-domain sequential recommendation

The cross-domain sequential recommendation aims to predict the next item based on a sequence of recorded user behaviours in multiple domains. We propose a novel Cross-domain Sequential Recommendation approach with Graph-Collaborative Filtering (CsrGCF) to alleviate the sparsity issue of user-interaction data. Specifically, we design time-aware and relation-aware graph attention mechanisms with collaborative filtering to exploit high-order behaviour patterns of users for promising results in both domains. Time-aware Graph Attention mechanism (TGAT) is designed to learn the inter-domain sequence-level representation of items. Relationship-aware Graph Attention mechanism (RGAT) is proposed to learn collaborative items' and users' feature representations. Moreover, to simultaneously improve the recommendation performance in the two domains, a Cross-domain Feature Bidirectional Transfer module (CFBT) is proposed, transferring user's common sharing features in both domains and retaining user's domain-specific features in a specific domain. Finally, cross-domain and sequential information jointly recommend the next items that users like. We conduct extensive experiments on two real-world datasets that show that CsrGCF outperforms several state-of-the-art baselines in terms of Recall and MRR. These demonstrate the necessity of exploiting high-order behaviour patterns of users for a cross-domain sequential recommendation. Meanwhile, retaining domain-specific features is an important step in the process of cross-domain feature bidirectional transferring.

A Review of Compensation Topologies and Control Techniques of Bidirectional Wireless Power Transfer Systems for Electric Vehicle Applications

Owing to the constantly rising energy demand, Internal Combustion Engine (ICE)-equipped vehicles are being replaced by Electric Vehicles (EVs). The other advantage of using EVs is that the batteries can be utilised as an energy storage device to increase the penetration of renewable energy sources. Integrating EVs with the grid is one of the recent advancements in EVs using Vehicle-to-Grid (V2G) technology. A bidirectional technique enables power transfer between the grid and the EV batteries. Moreover, the Bidirectional Wireless Power Transfer (BWPT) method can support consumers in automating the power transfer process without human intervention. However, an effective BWPT requires a proper vehicle and grid coordination with reasonable control and compensation networks. Various compensation techniques have been proposed in the literature, both on the transmitter and receiver sides. Selecting suitable compensation techniques is a critical task affecting the various design parameters. In this study, the basic compensation topologies of the Series–Series (SS), Series–Parallel (SP), Parallel–Parallel (PP), Parallel–Series (SP), and hybrid compensation topology design requirements are investigated. In addition, the typical control techniques for bidirectional converters, such as Proportional–Integral–Derivative (PID), sliding mode, fuzzy logic control, model predictive, and digital control, are discussed. In addition, different switching modulation schemes, including Pulse-Width Modulation (PWM) control, PWM + Phase Shift control, Single-Phase Shift, Dual-Phase Shift, and Triple-Phase Shift methods, are discussed. The characteristics and control strategies of each are presented, concerning the typical applications. Based on the review analysis, the low-power (Level 1/Level 2) charging applications demand a simple SS compensation topology with a PID controller and a Single-Phase Shift switching method. However, for the medium- or high-power applications (Level 3/Level 4), the dual-side LCC compensation with an advanced controller and a Dual-Side Phase-Shift switching pattern is recommended.

Partial phase transition induced bidirectional transfer of charge carriers in SrTiO3:γ/α-Bi2O3 heterojunction for ultrafast photodegradation of norfloxacin and bisphenol A

The phase transition in heterojunction preparation can greatly change the energy band configuration to tune the separation efficiency of photogenerated charge carriers. In this paper, γ-Bi2O3 partially converted into α-Bi2O3 to form triphase heterostructure SrTiO3:γ/α-Bi2O3 after insitu-growth of γ-Bi2O3 and SrTiO3 heterojunction. The photocatalytic degradation rates of the norfloxacin and the bisphenol A using the optimum sample are 0.13 min−1 and 0.09 min−1, much faster than that of any other catalysts reported previously. In the five cycling tests, the degradation rates of the norfloxacin and the bisphenol A are higher than 0.11 min−1 and 0.08 min−1 while the sample has good structural stability. The ultrafast photodegradation rates come from the partial phase transition inducing double Z-type energy band formation, realizing the bidirectional transfer of charge carriers to accelerate their separation. The SrTiO3 conduction band potential − 1.6 V and γ-/α-Bi2O3 valence band potential 2.3/1.75 V are preserved to generate O2•-, OH•, and hole for photocatalytic degradation. The degradation paths of these two pollutants are given via mass spectrum analysis and the final products are non-toxicity to environment by the growth by the Escherichia coli. The partial phase transition gives a novel idea for the designing of highly active heterojunction catalyst with multidirectional transfer of charge carriers.

King Ranch: Ranching on the edge

•The King Ranch in Wyoming, established in 1911, has for generations been “Ranching on the Edge” and adapting to new challenges as they operate on the perimeter of Wyoming's largest city, Cheyenne.•Lessons learned from King Ranch are highlighted regarding decision-making approaches, management strategies, and partnerships used to manage complex and highly variable systems for multiple goals.•Challenges presented to the King Ranch were turned into opportunities—“make lemonade when lemons are presented”—through creative collaborations resulting in new economic opportunities providing an avenue to involve the next family generation, leveraging existing skill sets of personnel on the ranch and ranch assets, and embracing community-centric relations.•Management-science partnerships involving multiple local, state, and federal entities on contemporary issues foster bidirectional knowledge transfer and learning for both ranchers and scientists.

Classification of 17 species Aegilops using DNA barcoding and SNPs, reveals gene flow among Aegilops biuncialis, Aegilops juvenalis, and Aegilops columnaris.

Rapid changes in agricultural environments caused by global warming pose a major challenge to food production and safety. Common wheat (Triticum aestivum) is a hexaploid plant (AABBDD) that shares large numbers of quantitative traits and resistance genes with B and D genomes of Aegilops species, which are responsible for several metabolic functions and biosynthetic processes, particularly in plant adaptation to biotic as well as abiotic stresses. Comparatively, the abundance of the Aegilops gene pool is much higher than that of Triticum. Therefore, we used four universal DNA barcodes for plants (ITS2, matK, rbcL, and psbM-petN) to construct a phylogenetic tree to classify the genus Aegilops. Fourteen species were distinguished among a total of 17 representative species. Aegilops biuncialis, Aegilops juvenalis, and Aegilops umbellulata could not be grouped into any of the clusters in the phylogenetic tree, indicating that these three species could not be distinguished by four DNA barcodes. Therefore, from 2408 SNPs obtained using genotyping by sequencing (GBS), we manually screened 30 SNPs that could be potentially used to classify these three species. The results of gene flow and genetic differentiation index (Fst) showed that the genetic differentiation among the three species was small, and there was bidirectional horizontal gene transfer between the three species, which was consistent with our results that the three species were difficult to classify by DNA barcode.

Two polarity reversal modes lead to different nitrate reduction pathways in bioelectrochemical systems

Polarity reversal is one of the effective strategies to rapidly start up denitrifying BESs，but the long-term performances of the denitrifying BESs operated under polarity reversal receive little attention. This study investigated the effects of periodic polarity reversal (PPR) and polarity reversal once only (PRO) on the long-term performances of denitrifying BESs. Repeatable oxidative and reductive currents were observed in the BESs obtained by PPR (PPR-BESs). The peak reductive currents of the PPR-BESs reached 0.95 A/m2, and nitrate was mainly removed by dissimilatory nitrate reduction to ammonium pathway with removal rates higher than 95 %. In contrast, the peak reductive currents of the BESs obtained by PRO (PRO-BESs) progressively decreased from 1.01 A/m2 to 0.12 A/m2. The nitrate removal rates of the PRO-BESs were <50 %, and the product of nitrate reduction turned to N2 instead of ammonium. 16S rDNA sequencing and metatranscriptomic analysis revealed that Geobacter capable of bidirectional extracellular electron transfer (EET) and Afipia capable of autotrophic growth were the dominant genera in the two types of BESs. Outer membrane cytochrome c and formate dehydrogenase were potentially involved in the cathodic electron uptake. These findings contribute to a better understanding of the EET mechanisms of electroautotrophic denitrifiers.

Comparative analysis of extracellular vesicle isolation methods from human AML bone marrow cells and AML cell lines.

Cellular crosstalk between hematopoietic stem/progenitor cells and the bone marrow (BM) niche is vital for the development and maintenance of myeloid malignancies. These compartments can communicate via bidirectional transfer of extracellular vesicles (EVs). EV trafficking in acute myeloid leukemia (AML) plays a crucial role in shaping the BM microenvironment into a leukemia-permissive niche. Although several EV isolation methods have been developed, it remains a major challenge to define the most accurate and reliable procedure. Here, we tested the efficacy and functional assay compatibility of four different EV isolation methods in leukemia-derived EVs: (1) membrane affinity-based: exoEasy Kit alone and (2) in combination with Amicon filtration; (3) precipitation: ExoQuick-TC; and (4) ultracentrifugation (UC). Western blot analysis of EV fractions showed the highest enrichment of EV marker expression (e.g., CD63, HSP70, and TSG101) by precipitation with removal of overabundant soluble proteins [e.g., bovine serum albumin (BSA)], which were not discarded using UC. Besides the presence of damaged EVs after UC, intact EVs were successfully isolated with all methods as evidenced by highly maintained spherical- and cup-shaped vesicles in transmission electron microscopy. Nanoparticle tracking analysis of EV particle size and concentration revealed significant differences in EV isolation efficacy, with exoEasy Kit providing the highest EV yield recovery. Of note, functional assays with exoEasy Kit-isolated EVs showed significant toxicity towards treated target cells [e.g., mesenchymal stromal cells (MSCs)], which was abrogated when combining exoEasy Kit with Amicon filtration. Additionally, MSC treated with green fluorescent protein (GFP)-tagged exoEasy Kit-isolated EVs did not show any EV uptake, while EV isolation by precipitation demonstrated efficient EV internalization. Taken together, the choice of EV isolation procedure significantly impacts the yield and potential functionality of leukemia-derived EVs. The cheapest method (UC) resulted in contaminated and destructed EV fractions, while the isolation method with the highest EV yield (exoEasy Kit) appeared to be incompatible with functional assays. We identified two methods (precipitation-based ExoQuick-TC and membrane affinity-based exoEasy Kit combined with Amicon filtration) yielding pure and intact EVs, also suitable for application in functional assays. This study highlights the importance of selecting the right EV isolation method depending on the desired experimental design.

Improved Feedback Control and Optimal Management for Battery Storage System in Microgrid Operating in Bi-Directional Grid Power Transfer

This paper presents an improved feedback controller and optimal management system to operate a battery storage system in a microgrid. The aim is to optimize the storage usage by reducing the battery degradation. The feedback controller regulates the battery current to track a reference despite uncertainties. It includes a disturbance observer to compensate unknown uncertainties and improve its tracking performance. The current reference is carried out using a management system based on the power balance in the microgrid connected to the main grid. Furthermore, the management system uses a coefficient to operate the battery depending on its constraints and the grid electricity price. This allows online optimization of the battery operation based on the price variations to reduce its degradation. The control and management systems are validated by simulation and the results are provided to demonstrate their effectiveness. Furthermore, experimentation is conducted to evaluate the control performance. The results show that the proposed feedback controller and disturbance observer provide better mean absolute error (0.0846) for the current tracking compared to only feedback controller (0.2073) and conventional proportional-integral controller (0.1126). Moreover, the proposed management system represents a reduction in the battery degradation by 74.56% compared to the conventional management system.