Differential Resistance Research Articles

Minigap-induced negative differential resistance in multilayer MoS2 -based tunnel junctions

Despite extensive research, the high-energy band properties of transition metal dichalcogenides remain unexplored. Here, we reveal that a multilayer MoS2-based tunnel junction exhibits substantial negative differential resistance (NDR) owing to the presence of a minigap, which is the energy gap between the upper and lower bands of the valence band at the Γ point. We fabricated a highly p-doped multilayer p+−MoS2/h-BN/p+−MoS2 tunnel junction. When a bias is applied across the junction, holes at the Fermi level at the Γ point in the valence band of the source-side p+−MoS2 resonantly tunnel to the drain-side p+−MoS2 with momentum conservation. When the energy of the injected hole coincides with the minigap of the drain-side p+−MoS2, the tunneling conductance is suppressed; thus, NDR is observed in the current-voltage characteristics. We identified minigap-induced NDR over a broad range of MoS2 thicknesses, including the bulk, that was observable even at room temperature. Published by the American Physical Society 2024

Негативний диференціальний опір і спектральні характеристики вихідних та опромінених електронами (з Е = 2 МеВ) світлодіодів GaAs1-xPx

The electrophysical and radiation characteristics of the original and irradiated electrons with E = 2 MeV GaAsP light emitting diodes were studied. The results of measurements of current-current characteristics in the range of 77 - 300 K are given. In the range of 180 - 77 K, a region of negative differential resistance was detected. The main characteristic parameters of light emitting diodes radiation are determined. The consequences of the effect of radiation defects on the emissivity and quantum yield of the studied structures are discussed.

Властивості вихідних та опромінених фосфідо-галієвих світлодіодів

Spectral features of the original and irradiated with electrons with E = 2 MeV GaP light emitting diodes (LEDs) were studied. Recombination lines of the exciton bound on the N isoelectronic center and on the pair complexes NN1 were detected. The change in the spectral composition of radiation when passing through a section of negative differential resistance is analyzed. Dose dependences of luminescence intensity were obtained for green GaP(N) and red GaP(Zn-O) LEDs. The maximum critical radiation dose was established, after which the LEDs lost their characteristic exciton emission mechanism. The results of the annealing of irradiated LEDs are given.

Effect of the Pyrolysis Temperature on the Negative Differential Resistance in Carbon/Vanadium Nanocomposite

Effect of the Pyrolysis Temperature on the Negative Differential Resistance in Carbon/Vanadium Nanocomposite

Switching Behavior and Negative Differential Resistance in a Carbon Matrix Based on Resorcinol-Formaldehyde

Switching Behavior and Negative Differential Resistance in a Carbon Matrix Based on Resorcinol-Formaldehyde

Variety-dependent responses of common tobacco with differential cadmium resistance: Cadmium uptake and distribution, antioxidative activity, and gene expression

Cadmium (Cd), which accumulates in tobacco leaves, enters the human body through inhalation of smoke, causing harmful effects on health. Therefore, identifying the pivotal factors that govern the absorption and resistance of Cd in tobacco is crucial for mitigating the harmful impact of Cd. In the present study, four different Cd-sensitive varieties, namely, ZhongChuan208 (ZC) with resistance, ZhongYan100 (ZY), K326 with moderate resistance, and YunYan87 (YY) with sensitivity, were cultivated in hydroponic with different Cd concentrations (20 µM, 40 µM, 60 µM and 80 µM). The results indicated that plant growth was significantly decreased by Cd. Irrespective of the Cd concentration, ZC exhibited the highest biomass, while YY had the lowest biomass; ZY and K326 showed intermediate levels. Enzymatic (APX, CAT, POD) and nonenzymatic antioxidant (Pro, GSH) systems showed notable variations among varieties. The multifactor analysis suggested that the ZC and ZY varieties, with higher levels of Pro and GSH content, contribute to a decrease in the levels of MDA and ROS. Among all the Cd concentrations, ZC exhibited the lowest Cd accumulation, while YY showed the highest. Additionally, there were significant differences observed in Cd distribution and translocation factors among the four different varieties. In terms of Cd distribution, cell wall Cd accounted for the highest proportion of total Cd, and organelles had the lowest proportion. Among the varieties, ZC showed lower Cd levels in the cell wall, soluble fraction, and organelles. Conversely, YY exhibited the highest Cd accumulation in all tissues; K326 and ZY had intermediate levels. Translocation factors (TF) varied among the varieties under Cd stress, with ZC and ZY showing lower TF compared to YY and K326. This phenomenon mainly attributed to regulation of the NtNramp3 and NtNramp5 genes, which are responsible for the absorption and transport of Cd. This study provides a theoretical foundation for the selection and breeding of tobacco varieties that are resistant to or accumulate less Cd.

Various amino acid substitutions in succinate dehydrogenase complex regulating differential resistance to pydiflumetofen in Magnaporthe oryzae

Rice blast, caused by Magnaporthe oryzae, is a devastating fungal disease worldwide. Pydiflumetofen (Pyd) is a new succinate dehydrogenase inhibitor (SDHI) that exhibited anti-fungal activity against M. oryzae. However, control of rice blast by Pyd and risk of resistance to Pyd are not well studied in this pathogen. The baseline sensitivity of 109 M. oryzae strains to Pyd was determined using mycelial growth rate assay, with EC50 values ranging from 0.291 to 2.1313 μg/mL, and an average EC50 value of 1.1005 ± 0.3727 μg/mL. Totally 28 Pyd-resistant (PydR) mutants with 15 genotypes of point mutations in succinate dehydrogenase (SDH) complex were obtained, and the resistance level could be divided into three categories of very high resistance (VHR), high resistance (HR) and moderate resistance (MR) with the resistance factors (RFs) of >1000, 105.74–986.13 and 81.92–99.48, respectively. Molecular docking revealed that all 15 mutations decreased the binding-force score for the affinity between Pyd and target subunits, which further confirmed that these 15 genotypes of point mutations were responsible for the resistance to Pyd in M. oryzae. There was positive cross resistance between Pyd and other SDHIs, such as fluxapyroxad, penflufen or carboxin, while there was no cross-resistance between Pyd and carbendazim, prochloraz or azoxystrobin in M. oryzae, however, PydR mutants with SdhBP198Q, SdhCL66F or SdhCL66R genotype were still sensitive to the other 3 SDHIs, indicating lack of cross resistance. The results of fitness study revealed that the point mutations in MoSdhB/C/D genes might reduce the hyphae growth and sporulation, but could improve the pathogenicity in M. oryzae. Taken together, the risk of resistance to Pyd might be moderate to high, and it should be used as tank-mixtures with other classes of fungicides to delay resistance development when it is used for the control of rice blast in the field.

Negative Differential Resistance in Single‐Molecule Junctions Based on Heteroepitaxial Spherical Au/Pt Nanogap Electrodes

AbstractSingle‐molecule junctions exploit the internal structure of molecular orbitals to construct a new class of functional quantum devices. The demonstration of negative differential resistance (NDR) in single‐molecule junctions is direct evidence of quantum mechanical tunneling through a molecular orbital. Here, a pronounced NDR effect is reported with a peak‐to‐valley ratio of 30.1 on a single‐molecule junction of π‐conjugated quinoidal‐fused oligosilole derivatives, Si2 × 2, embedded between the unique electroless gold‐plated heteroepitaxial spherical Au/Pt nanogap electrodes. This NDR feature persists in a consecutive endurance test of 180 current traces. the thermally stable NDR effects in the Si2 × 2 single‐molecule junctions between 9 and 300 K are demonstrated. The density functional theory calculations under electric fields indicate that the NDR effect can be ascribed to the bias‐dependent resonant tunneling transport via the polarized HOMO, which has asymmetrically changed electrode coupling with increased bias voltages. The results confirm a promising electrical platform for constructing functional quantum devices at the single‐molecule level.

Effects of Current Filaments on IGBT Avalanche Robustness: A Simulation Study

With the increase in voltage level and current capacity of the insulated gate bipolar transistor (IGBT), the avalanche effect has become an important factor limiting the safe operating area (SOA) of the device. The hole injection into the p/n junction on the backside of the IGBT after avalanche is the main feature that distinguishes the avalanche effect from other devices. In this paper, the avalanche breakdown characteristics of IGBT and the nature of current filament are investigated using theoretical analysis and numerical simulation, and the underlying physical mechanism controlling the nature of current filaments is revealed. The results show that the hole injection on the backside of the IGBT leads to an additional negative differential resistance (NDR) branch on the avalanche breakdown curve. The device’s common-base current gain, αpnp, is a crucial factor in determining the current filament. As αpnp increases, the avalanche-induced current filament becomes stronger and slower, resulting in weaker avalanche robustness of the device.

Unraveling the intricate relationship between lipid metabolism and oncogenic signaling pathways.

Lipids, the primary constituents of the cell membrane, play essential roles in nearly all cellular functions, such as cell-cell recognition, signaling transduction, and energy provision. Lipid metabolism is necessary for the maintenance of life since it regulates the balance between the processes of synthesis and breakdown. Increasing evidence suggests that cancer cells exhibit abnormal lipid metabolism, significantly affecting their malignant characteristics, including self-renewal, differentiation, invasion, metastasis, and drug sensitivity and resistance. Prominent oncogenic signaling pathways that modulate metabolic gene expression and elevate metabolic enzyme activity include phosphoinositide 3-kinase (PI3K)/AKT, MAPK, NF-kB, Wnt, Notch, and Hippo pathway. Conversely, when metabolic processes are not regulated, they can lead to malfunctions in cellular signal transduction pathways. This, in turn, enables uncontrolled cancer cell growth by providing the necessary energy, building blocks, and redox potentials. Therefore, targeting lipid metabolism-associated oncogenic signaling pathways could be an effective therapeutic approach to decrease cancer incidence and promote survival. This review sheds light on the interactions between lipid reprogramming and signaling pathways in cancer. Exploring lipid metabolism as a target could provide a promising approach for creating anticancer treatments by identifying metabolic inhibitors. Additionally, we have also provided an overview of the drugs targeting lipid metabolism in cancer in this review.

Electronic and transport properties of U-cut edge patterned AGNR superlattice for RTD application

In this paper, we first characterize a superlattice structure created by repeating a heterostructure formed from two armchair graphene nanoribbon (AGNR) segments with different widths. We investigate the electronic and transport properties of this structure by varying its widths and lengths to demonstrate the tunability of its overall band gap. The plot of the local density of states shows the formation of localized states at the low band gap segments of the superlattice. The superlattice is then used as a barrier to create a double barrier quantum well (DBQW) to design a proposed resonant tunneling diode (RTD) structure. We observe this device's negative differential resistance (NDR) operation for a range of bias voltages between the contacts. We study the effect of dimensional parameters on the RTD performance. The non-equilibrium Green's function method, based on a tight-binding model, is employed for numerical computation.

Harnessing Quantum Capacitance in 2D Material/Molecular Layer Junctions for Novel Electronic Device Functionality.

Two-dimensional (2D) materials promise advances in electronic devices beyond Moore's scaling law through extended functionality, such as non-monotonic dependence of device parameters on input parameters. However, the robustness and performance of effects like negative differential resistance (NDR) and anti-ambipolar behavior have been limited in scale and robustness by relying on atomic defects and complex heterojunctions. In this paper, we introduce a novel device concept that utilizes the quantum capacitance of junctions between 2D materials and molecular layers. We realized a variable capacitance 2D molecular junction (vc2Dmj) diode through the scalable integration of graphene and single layers of stearic acid. The vc2Dmj exhibits NDR with a substantial peak-to-valley ratio even at room temperature and an active negative resistance region. The origin of this unique behavior was identified through thermoelectric measurements and ab initio calculations to be a hybridization effect between graphene and the molecular layer. The enhancement of device parameters through morphology optimization highlights the potential of our approach toward new functionalities that advance the landscape of future electronics.

Transcriptional Comparison Reveals Differential Resistance Mechanisms between CMV-Resistant PBC688 and CMV-Susceptible G29.

The Cucumber mosaic virus (CMV) presents a significant threat to pepper cultivation worldwide, leading to substantial yield losses. We conducted a transcriptional comparative study between CMV-resistant (PBC688) and -susceptible (G29) pepper accessions to understand the mechanisms of CMV resistance. PBC688 effectively suppressed CMV proliferation and spread, while G29 exhibited higher viral accumulation. A transcriptome analysis revealed substantial differences in gene expressions between the two genotypes, particularly in pathways related to plant-pathogen interactions, MAP kinase, ribosomes, and photosynthesis. In G29, the resistance to CMV involved key genes associated with calcium-binding proteins, pathogenesis-related proteins, and disease resistance. However, in PBC688, the crucial genes contributing to CMV resistance were ribosomal and chlorophyll a-b binding proteins. Hormone signal transduction pathways, such as ethylene (ET) and abscisic acid (ABA), displayed distinct expression patterns, suggesting that CMV resistance in peppers is associated with ET and ABA. These findings deepen our understanding of CMV resistance in peppers, facilitating future research and variety improvement.

The Negative Differential Resistance Effect of Substitutional Doped Monolayer GeS and Its Application in Gas Sensor

The Negative Differential Resistance Effect of Substitutional Doped Monolayer GeS and Its Application in Gas Sensor

22‐3: Negative Capacitance ZAO/ZnO Ferroelectric Thin‐Film Transistor for Neuromorphic Computing

We report complementary metal‐oxide semiconductor (CMOS)‐compatible, negative capacitance (NC) ferroelectric (FE) zirconium‐aluminum oxide (ZAO)/ZnO thin‐film transistors (TFTs) at a low thermal budget of 360 °C. The NC‐FE‐TFTs demonstrate uniform device‐to‐device performances, featuring a high memory window of 6.7 ± 0.1 V and steep subthreshold swing of 43 ± 4 mV dec–1 . The observation of negative differential resistance at room temperature confirms the NC effect in FE‐ZAO/ZnO TFTs. In addition, a learning accuracy of ≈92% is achieved, highlighting the potential for high precision neuromorphic computing application.

Fluid-Solid Interfacial Properties and Drag-Reducing Characterization of the Flexible Conical Microstructured Film Inspired by the Streamlined Body Surface of the Pufferfish.

Given the challenges in accurately replicating the surface of the pufferfish, this study employed three-dimensional (3D) printing to create a model based on inverse modeling. The morphology of the pufferfish exhibits a streamlined configuration, characterized by a gradual widening from the anterior oral region to the central ocular area, followed by a progressive narrowing from the midabdominal region toward the caudal extremity. The RNG k-ε turbulence simulation results demonstrate that the streamlined body surface of the pufferfish diminishes differential pressure resistance. This enhancement promotes laminar flow formation, delays fluid separation, minimizes turbulence-induced vortices, and reduces frictional resistance. Moreover, the pufferfish's supple and uneven outer epidermis was simplified into a flexible, nonsmooth planar film to conduct fluid-solid coupling simulations. These revealed that the pufferfish's unique skin can absorb turbulent energy and minimize momentum transfer between the fluid and the solid film, lowering the fluid resistance during swimming. In summary, The high-efficiency swimming capacity of pufferfish stems not only from their streamlined body surface but also significantly from the unique structural characteristics and mechanical properties of their flexible skin. This research provides critical theoretical underpinnings for the design of functional bionic surfaces aimed at drag reduction.

Double ferromagnetic barriers resonant tunneling diodes (RTD) based on the surface of a topological insulator

Resonant tunneling diodes (RTDs), which are based on double barrier quantum well structures, are typically achieved by combining different materials with varying band gap sizes. However, this approach often poses challenges such as material mismatching and dislocations. In this study, we present a novel resonant tunneling diode scheme utilizing the unique properties of topological insulator materials. Specifically, we exploit the gap opening in the band structure of the topological insulator by employing perpendicular magnetization. In this proposed RTD platform, the barrier regions are formed from a ferromagnetic topological insulator through the proximity effect. By adjusting the thickness and spacing of the ferromagnetic barriers, a well region with confined states emerges between the barrier regions. Theoretical analysis reveals that by tuning the back gate voltage, the I-V characteristics exhibit two significant behaviors: negative differential resistance (NDR) and step-like behavior for Fermi energy values of EF = −3 and EF = 3, respectively. Furthermore, we observe an increase in the peak-to-valley ratio (PVR) with higher magnetization values. Notably, the PVR reaches a value of 7.13 for a magnetization value of m = 9. Additionally, we investigate the influence of the well width and barrier thickness on the transport properties of the device.

Studying quantum effects of fine scaling on the buckling behavior of CNTs under torsional loading using the density functional theory and molecular mechanics approach

In this study, we introduce a comprehensive investigation into the buckling behavior of carbon nanotubes (CNTs) using a combined approach of quantum mechanics and molecular mechanics methods. A novel aspect of our research lies in the exploration of the quantum effects of fine scaling on the buckling behavior of finite‐length nanotubes across various dimensions and chiralities. Specifically, we analyze the critical buckling strain variations in CNTs with distinct lengths, diameters, and chiralities, revealing pronounced differences influenced by atomic arrangement and the type of structure used in nanotube construction. Our findings elucidate that at smaller dimensions, nanotubes exhibit a higher critical buckling strain than other chiralities, while zigzag atomic arrangements demonstrate greater resistance to torsional loading at larger diameters. Additionally, we compare the buckling behavior of nanotubes obtained by wrapping armchair and zigzag nanosheets, highlighting differential resistance trends. This research not only underscores the critical role of quantum effects in determining nanotube buckling but also provides valuable insights into the nuanced influences of atomic arrangement and nanosheet type on the mechanical properties of CNTs. Thus, our work contributes a novel perspective to the field, bridging the gap between quantum mechanics and the mechanical behavior of nanostructures, which has significant implications for the design and application of nanoscale materials

High rectification effects of heterojunctions based on C3N4 nanoribbons

Two heterojunctions based on zigzag graphitic carbon nitride nanoribbons (ZCNNRs), namely, BnAn and CnAn, are considered and their electronic transport properties are studied using the nonequilibrium Green's function (NEGF) in combination with the density functional theory (DFT). The BnAn is formed by the joining of bare and partially hydrogenated ZCNNRs. The CnAn is created by the attachment of bare and fully hydrogenated ZCNNRs which leads to a Schottky barrier. The results show that current–voltage characteristics (I–V) can be significantly tuned by the length variation of heterojunctions. Furthermore, it is found that both heterojunctions have a remarkable nonlinear behavior in the whole bias range. The B4A4, B3A4, and B4A3 have forward rectifier performance whereas B2A2, B3A3, C2A2, C3A3, C4A4, C3A4, C4A3, C5A3, and C6A3 show the reverse rectification behavior. In the case of BnAn, the maximum rectification ratio (RR) of B4A4 is boosted up to 3.97 × 107 at 0.4 V. Additionally, for CnAn, the maximum RR of C4A3 can reach 1.37 × 105 at 1.0 V. Our investigation reveals that the BnAn heterojunction has negative differential resistance (NDR) under positive bias.The peculiar transport behaviors of B4A4 and C4A3 are explained due to the energy level shifts of electrodes with applied bias voltage and great alterations in the transmission spectrum. Furthermore, the Molecular projected self-consistent Hamiltonian (MPSH) and projected local density of states (PLDOS) are analyzed for these devices. The findings of this work reveal unique opportunities to design the ZCNNRs nanoelectronic devices.

Characterizing the differential susceptibility and resistance to insecticides in populations of Chrysodeixis includens and Rachiplusia nu (Lepidoptera: Noctuidae) in Brazil.

Chrysodeixis includens (Walker) and Rachiplusia nu (Guenée) are major Plusiinae pests of soybean in the Southern Cone region of South America. In recent decades, C. includens was the main defoliator of soybean in Brazil, but from 2021 onwards, R. nu emerged as an important soybean pest in various regions of the country. Here, we characterize the differential susceptibility and resistance to insecticides in these Plusiinae pests from two soybean regions of Brazil. Except for spinetoram and chlorfenapyr (comparable lethality against both species) and a Bt-based biopesticide (more lethal for C. includens), the tested insecticides showed higher lethality against R. nu than against C. includens, but populations of the same species, even separated by long distances, presented similar resistance levels. For both species, the 90% lethal concentration (LC90) values of most insecticides were higher than the field-recommended dose. Nevertheless, the field-recommended doses of spinetoram, metaflumizone, emamectin benzoate, cyclaniliprole and chlorfenapyr showed comparable control efficacy against both species, whereas indoxacarb, chlorantraniliprole, flubendiamide, teflubenzuron and chlorfluazuron were more lethal for R. nu, and methoxyfenozide and the Bt-based insecticide were more lethal for C. includens. Thiodicarb, methomyl and lambda-cyhalothrin showed low lethality against both species. Large interspecific differences in the susceptibility to insecticides was found in major Plusiinae pests of soybean in Brazil. Furthermore, variations in susceptibility to insecticides occurred consistently among species and populations, regardless of the collection site and thus despite unequal temporal and spatial exposure to insecticides. These results demonstrate that accurate species identification is essential for effective control of Plusiinae in soybean. © 2024 Society of Chemical Industry.