Abstract
We propose an adiabatic superconducting charge pump based on massive Dirac electrons. A superconductor is sandwiched in between two pumping sources, which are formed by introducing the ...time-dependent and out-of-phase staggered potentials in graphene as pumping parameters. The pump is shown to be characterized by not only the topological interface state (TIS) but also the non-topologically quasi interface state (QIS). Hereafter, our attention is focused on the pumping currents
I
L
NR
and
I
L
AR
from the normal and Andreev reflections, respectively, which predominate by making the electron energy reside in the effective energy gap. It is found that modulating the energy
E
, superconductor length
L
0
, and pumping source length
L
P
results in the considerable variation of competitive behaviors between
I
L
NR
and
I
L
AR
. In particular, the reversal effect of current direction can be realized by tuning
L
P
. More interestingly, the current-phase relationship exhibits the platform behaviors, which can be manipulated by
L
P
and the pumping strength. All the above pumping properties are attributed to the adiabatic evolution of TIS and non-topologically QIS, particularly the conversion between each other is the crucial origin. We also obtain the quantized pumping current by adjusting
L
P
and
L
0
, and present the corresponding qualitative explanation through the pumping contour circled by the two parameters. In addition, we discuss the features of pumping current based on the armchair graphene as well.
Abstract Current theoretical and experimental endeavors to realize an anomalous Floquet chiral topological superconductor (TSC), which is characterized by chiral Majorana edge modes independent of ...the Chern number, remain insufficient. Herein, we propose a new scheme that involves jointly tuning dynamic driving and static parameters within a magnetic topological insulator-superconductor sandwich structure to achieve this goal. The Josephson phase modulation induced by an applied bias voltage across the structure is utilized as a Floquet periodic drive. It is found that the interplay between the two kinds of tunings can bring about a lot more exotic Floquet TSC phases than those caused by only tuning the dynamic driving parameter (frequency ω or period τ ). More importantly, just tuning static parameters (the chemical potential µ , Zeeman field g z , and proximity-induced superconducting energy gap Δ b ) also can induce a series of novel topological phase transitions. Particularly, the features in the context of the three tunings are different from each other, originating from the combination of intrinsic and different extrinsic mechanisms. In addition, jointly tuning τ and µ ( g z ) can have its own unique TSC phases. The proposed scheme should be readily accessible in experiments, and thus the family of anomalous Floquet TSC phases may be considerably enriched.
With the increasing number of vehicles connected to the Internet of Vehicles (IoV), to accommodate the evolving needs and patterns of new vehicles, passengers, and drivers, traditional single Trusted ...Authority (TA) authentication model may no longer be suitable for the IoV scenario, it is crucial to develop secure, lightweight, efficient, and cross-TA identity authentication and key agreement algorithms. In 2021, Xu et al. proposed a blockchain-based Roadside Unit (RSU)-assisted authentication and key agreement protocol for IoV. However, we describe that their protocol is vulnerable to identity guessing attacks, vehicle forgery attacks, and lacks of session key security and known session key secrecy, and propose a novel blockchain and elliptic curve cryptography-based cross-TA authentication and key agreement protocol for IoV. Our protocol uses Physical Unclonable Functions (PUF) and biometric keys to resist RSU capture attacks and Onboard Unit (OBU) intrusion attacks. Formal security proof and comparative analysis indicate that the proposed protocol can resist various known attacks and maintains lower computational complexity.
We report the synthesis of TiO2 hierarchical spheres (THS) with large specific surface area via a facile one-pot solvothermal method. The as-prepared THS are self-assembled by ultrathin TiO2 ...nanosheets with thickness of several nanometers and they show a uniform spherical morphology with an average size of 500–700 nm. However, the as-prepared light yellow THS exhibit inferior photocatalytic activity for hydrogen evolution from water splitting due to the poor crystallization of TiO2 and the existence of oxygen vacancies. Significantly, a subsequent thermal treatment improves the crystallinity of THS, reduces the oxygen vacancies, and thereby enhances the photocatalytic performance. It demonstrates that the sample annealed at 550 °C (THS550) exhibits the highest photocatalytic activity, about 5 times higher than that of commercial TiO2 nanoparticles (CTiO2). Moreover, the THS550 sample loaded with 1 wt% Pt exhibits an hydrogen evolution rate as high as 17.9 mmol h−1g−1, and the corresponding apparent quantum efficiency has been determined to be 28.46% under 350 nm light irradiation.
Display omitted
•THS assembled by ultrathin nanosheets are synthesized via a solvothermal method.•Poor crystallization and oxygen vacancies induce low photocatalytic activity of THS.•THS annealed at 550 °C exhibits superior photocatalytic activity.•THS550 with 1 wt% Pt exhibits a hydrogen evolution rate of 17.9 mmol h−1g−1.
Defence against pathogens relies on intracellular nucleotide-binding, leucine-rich repeat immune receptors (NLRs) in plants. Hormone signaling including abscisic acid (ABA) pathways are activated by ...NLRs and play pivotal roles in defence against different pathogens. However, little is known about how hormone signaling pathways are activated by plant immune receptors. Here, we report that a plant NLR Sw-5b mimics the behavior of the ABA receptor and directly employs the ABA central regulator PP2C-SnRK2 complex to activate an ABA-dependent defence against viral pathogens. PP2C4 interacts with and constitutively inhibits SnRK2.3/2.4. Behaving in a similar manner as the ABA receptor, pathogen effector ligand recognition triggers the conformational change of Sw-5b NLR that enables binding to PP2C4 via the NB domain. This receptor-PP2C4 binding interferes with the interaction between PP2C4 and SnRK2.3/2.4, thereby releasing SnRK2.3/2.4 from PP2C4 inhibition to activate an ABA-specific antiviral immunity. These findings provide important insights into the activation of hormone signaling pathways by plant immune receptors.
In Internet of Things (IoT)-based healthcare, sensor nodes are deployed to detect the patient’s physiological data in a wireless sensor network. In order to prevent unwarranted users from accessing ...the sensor network to obtain patients’ data, designing lightweight and privacy-preserving authentication protocols plays a crucial role. Many lightweight authentication protocols for IoT-based healthcare have been proposed in recent years, but most of them may suffer from one or more security problems. In particular, few protocols can resist sensor node-captured attacks and achieve n-factor secrecy, which leads to unauthorized personnel being able to access the patient’s physiological data and obtain patients’ privacy. Therefore, a lightweight and privacy-preserving authentication protocol for healthcare based on elliptic curve cryptography (ECC) and physical unclonable function (PUF) is proposed to surmount the above obstacles. We design a dynamic anonymity strategy to achieve users’ anonymity and unlinkability and use PUF to protect information stored in users’ devices and sensor nodes. In addition, higher security features such as three-factor secrecy, perfect forward secrecy, resistance to sensor node-captured attacks, and update asynchronous attacks are guaranteed. The proposed protocol is proven to be secure under the random oracle model and maintains lightweight computing efficiency.
Software defect prediction can predict the defective modules in the project in advance, which is helpful to optimize the allocation of test resources. Recently, privacy protection for datasets and ...models has gradually attracted the attention of researchers. In this study, we are the first to apply homomorphic encryption to software defect prediction model construction and propose a novel method HOPE. Specifically, we adopt an algorithm approximation strategy to approximate the sigmoid function and select the Paillier homomorphic encryption algorithm for Logistical regression. In our case study, we choose the MORPH dataset gathered from real-world open-source projects as our experimental subjects. Then we design three control groups to simulate three different scenarios based on whether the client sends the encrypted data to the server and whether the server uses the HOPE method. The final results show that if the server uses the original Logistic regression to construct the model on the encrypted data, the performance of the trained model is similar to random guess, which can guarantee the privacy protection of the data. Moreover, compared with the original Logistical regression method, the method HOPE only needs a small amount of computational cost, but there is no obvious performance decrease. We share our implementation scripts and datasets to encourage researchers to conduct more studies on this research direction.
The feeding relationship between copepods and phytoplankton has immense ecological significance. This study investigated the feeding behavior of copepods by studying the feeding selectivity of ...Paracalanus parvus, a key small copepod species, using a high-speed camera. The feeding behavior of P. parvus separately fed on three algae, Prorocentrum minimum, Alexandrium minutum, and Thalassiosira weissflogii, was studied at five different concentrations. The factors characterizing feeding behavior, including the beating frequency (BF), beating time (BT), and rejection behavior, were analyzed. The average BT and BF of P. parvus fed on toxic algae were significantly lower than those of copepods fed on nontoxic algae, indicating that the toxic algae negatively affected their feeding behavior. There were no significant differences in feed rejection among the three algae during the short period of experimentation, indicating that the rejection behavior was insignificant in the early period (within 20 min) of feeding on toxic algae. The feeding behavior was inhibited when the concentration reached 250 cells/mL. The BT was initially affected at increasing concentrations followed by the BF, and P. minimum and A. minutum reduced the BF at concentrations of 250 and 1000 cells/mL, respectively. Analysis of the average BFs revealed that P. parvus was more significantly affected by P. minimum containing diarrheal shellfish poison than by A. minutum containing paralytic shellfish poison. The BF of copepods fed on P. minimum was significantly lower than that of copepods fed on A. minutum at 250–500 cells/mL but was not significantly different from that at 1000 cells/mL. This indicated that the inhibitory effect of P. minimum on the feeding behavior was more significant at concentrations observed at the onset of red tide blooms (0.25–0.5 × 102 cells/mL), but insignificant at concentrations reaching those in advanced red tides (>103 cells/mL). This study demonstrates that toxic dinoflagellates alter the feeding behavior of copepods and describes the variations in their feeding response to different algal species and concentrations. The findings provide crucial insights for further studies on the feeding relationship between copepods and phytoplankton and on functional assessment of plankton ecosystems.
A tigecycline-resistant
Acinetobacter pittii
clinical strain from pleural fluid carrying a
bla
NDM–1
gene and a novel
bla
OXA
gene,
bla
OXA–1045
, was isolated and characterized. The AP2044 strain ...acquired two copies of the
bla
NDM–1
gene and six antibiotic resistance genes (ARGs) from other pathogens. According to the whole-genome investigation, the GC ratios of ARGs (50–60%) were greater than those of the chromosomal backbone (39.46%), indicating that ARGs were horizontally transferred. OXA-1045 belonged to the OXA-213 subfamily and the amino acid sequence of OXA-1045 showed 89% similarity to the amino acid sequences of OXA-213. Then,
bla
OXA–1045
and
bla
OXA–213
were cloned and the minimum inhibitory concentrations (MICs) of β-lactams in the transformants were determined using the broth microdilution method. OXA-1045 was able to confer a reduced susceptibility to piperacillin and piperacillin-tazobactam compared to OXA-213. AP2044 strain exhibited low pathogenicity in
Galleria mellonella
infection models. The observation of condensed biofilm using the crystal violet staining method and scanning electron microscopy (SEM) suggested that the AP2044 strain was a weak biofilm producer. Quantitative reverse transcription-PCR (qRT-PCR) was used to detect the expression of resistance-nodulation-cell division (RND) efflux pump-related genes. The transcription level of
adeB
and
adeJ
genes increased significantly and was correlated with tigecycline resistance. Therefore, our genomic and phenotypic investigations revealed that the AP2044 strain had significant genome plasticity and natural transformation potential, and the emergence of antibiotic resistance in these unusual bacteria should be a concern for future investigations.
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