High Leakage Research Articles

Epitaxial growth of AlGaN/GaN HEMTs on patterned Si substrate for high voltage power switching applications

In this work, a series of AlGaN/GaN high electron mobility transistors (HEMTs) have been grown on patterned (Al)GaN-on-Si seed layers by metalorganic chemical vapor deposition (MOCVD) to study the effect of the (Al)GaN buffer thickness and its aluminum content on the vertical breakdown voltage. The atomic force microscopy (AFM) analysis performed on the GaN seed layers shows a perfectly smooth, MOCVD-like morphology with a threading dislocation density (TDD) around 2 × 109 cm−2. We succeeded to regrow up to 10 μm and 5 μm crack-free GaN + HEMT and Al0.30G0.70N + HEMT structures, respectively and scanning electron microscopy (SEM) revealed limited lateral growth on mesas with few microscopic defects while AFM show the same surface morphology of HEMT structures as ones grown on planar substrates. NiAu Schottky contacts were deposited on the regrown (Al)GaN HEMTs as well as on (Al)GaN seed layer structures. No breakdown was noticed up to 200 V for the regrown Al0.30Ga0.70N (3 μm) HEMT and the GaN seed layer structures and the leakage current remained in the range of 1 nA. However, the leakage current in the regrown GaN (5 μm) structure reached rapidly 1 mA. Such a high leakage was not noticed for non-patterned devices. Thus, it is possibly attributed to silicon contamination in the regrown GaN layer. On the other hand, the absence of noticeable leakage in the regrown 3 μm thick Al-rich AlGaN buffer HEMT opens the way to a new competitive solution for high power electronics applications on silicon substrate.

Bismuth ferrite-barium titanate system studies around morphotropic phase boundary

Nowadays, the electro-electronic industry and scientific community have a great interest in improving memory devices. A candidate is the bismuth ferrite owing to the coexistence of ferroelectricity and anti-ferromagnetism at room temperature, however, a high leakage current harms their ferroelectric properties. Thus, bismuth ferrite and barium titanate solutions improve the ferroelectric properties of bismuth ferrite and optimize the magnetoelectric coupling factor. This system is called multiferroic, materials exhibit the coexistence of ferromagnetic, ferroelectric, or ferro-elastic orders, which is of interest to the scientific physics community and electronic industry. In this paper, bismuth ferrite-barium titanate system around the morphotropic phase boundary was studied and analyzed. It was observed changes in the structural properties in function of barium titanate content. Calcination temperature was determined from thermogravimetric analysis curves to powders of bismuth ferrite-barium titanate system. Ceramic bodies were densified conventionally. Archimedes’ method was used for density measure. Ceramics with densities greater than 95% were obtained. 93% of the perovskite phase was obtained from structural results. Finally, structural properties were presented and analyzed using Mossbauer spectroscopy as complementary technique. These analyses are very important in solid state physics because to contribute to understanding the phenomenology and synthesis process of multiferroic materials.

The Efficiency of Humic Acid for Improving Salinity Tolerance in Salt Sensitive Rice (Oryza sativa): Growth Responses and Physiological Mechanisms

High-yielding rice cultivars exhibit a great performance in non-saline fields; however, their growth and productivity are greatly reduced in salt-affected lands. Humic acid has a promising stress-mitigating potential and can be effective in improving salt tolerance in salinity sensitive rice cultivars. Herein, seeds of Giza 177 (high-yielding but salt-sensitive rice cultivar) were primed in 40 mg/l humic acid, sown, and maintained. Then growth and physiological responses of the humic acid-primed plants to increased levels of salinity (EC: 0.55, 3.40, 6.77, and 8.00 mS/cm) were evaluated at the reproductive stage. Increasing salinity induced a progressive retardation in plant height, leaf area, fresh and dry weights. Such retardation was associated with Na+ buildup in shoot and root, high electrolyte leakage and accumulation of malondialdehyde, total soluble sugars, sucrose, glucose, proline, total soluble proteins, flavonoids, and phenolics. In contrast, salinity reduced K+, K+/Na+ ratio, total carbohydrates, and the activity of catalase, peroxidase, and polyphenol oxidase. Humic acid enhanced growth under non-saline and saline conditions. The humic acid-induced improvement in salt tolerance was associated with the reduction of Na+ toxicity, increasing K+/Na+ ratio, regulating osmolytes concentration, and enhancing the activities of antioxidant enzymes and thus reduce the oxidative stress. These results indicate that humic acid successfully reduced the salinity-induced plant damage, improved metabolism, and maintained active growth of Giza 177 under saline irrigation.

A new apparatus for investigating gas transport property in geomaterials with ultralow permeability

The gas flow in geological materials with ultra-low permeability can vary dramatically, i. e., from almost no measurable quantity of gas before breakthrough to a massive gas flux at breakthrough. It is a great challenge to realize the whole process measurement of gas transport in saturated geomaterials with ultra-low permeability. In this work, a newly designed temperature-controlled triaxial apparatus was developed. In which, a water-to-gas-exchanger was designed for precise injection of gas at a constant pressure or constant injection rate, due to that water is less compressible and much more difficult to leak through the seal of a regulator. Meanwhile, eddy current sensors and displacement transducer with high resolutions were utilized to accurately measure the specimen deformation at different locations in a non-contact way to explore the mechanism of gas entry and breakthrough. In addition, a gas flow detection device that contains four gas flowmeters with different measurement ranges and can automatically switch between these flowmeters was developed to monitor the gas outflow of the whole process. To validate the performance of the developed apparatus, systematic gas injection tests on Gaomiaozi (GMZ) bentonite were conducted, during which the helium gas was injected in a constant rate. Real-time data on inlet gas pressure, gas outflow rate, stress state (both isotropic and axial stresses) and volume deformation (both axially and radially) were monitored. Results show that the developed apparatus could successfully capture the gas entry and the subsequent breakthrough points of the compacted bentonite with ultralow permeability. For compacted bentonite with high saturation, capillary flow, dilatant flow and interfacial leakage could co-exist during the gas transport process and the dominated mechanism was closely related to the gas injection pressure.

A semi-analytical model for multi-well leakage in a depleted gas reservoir with irregular boundaries

Depleted gas reservoirs are potential sites for CO2 geo-sequestration (CGS). Improperly sealed wells may provide leakage pathways and increase the risk of environmental contamination. A fast and efficient method for injection performance monitoring and leakage risk assessment is essential for implementing CGS projects. This paper presents a new semi-analytical model for predicting the transient behavior of the injection pressure and leakage rate during CO2 injection. The proposed model considers the leakage through multiple abandoned wells and the effect of boundary irregularities on the injection performance. First, the CO2 seepage model for the depleted gas reservoir and the overlying aquifer is derived. Then, the boundaries are discretized into segments, given the boundary irregularities. Using the boundary element method (BEM), Laplace transform, and Duhamel’s principle, the mathematical model is solved, and the solutions are compared with those from numerical simulations for verification. Based on a case study of the Dongfang 1-1 gas field, the impacts of the parameters of the reservoir and leaky well on the injection performance and leakage rate are analyzed.The proposed model has a good fit with the results of the numerical simulations. The sensitivity analysis demonstrates that the cumulative leakage ratio increases linearly with the upper limit of injection pressure and reservoir permeability. The leakage risk induced by the leaky wells is relatively low in the reservoir with low permeability because of high seepage resistance and limited pressure propagation. However, the storage potential is restricted due to the poor injectability. The rate of CO2 inter-layer flow is determined by the leakage permeability of all of the abandoned wells, not just those with a high leakage permeability. Reservoirs with multiple abandoned wells and a large overlying aquifer are still at the risk of gas leakage even if the leakage permeability of the abandoned wells is low.

Evolution of High Dielectric Permittivity in Low-Temperature Solution Combustion-Processed Phase-Pure High Entropy Oxide (CoMnNiFeCr)O for Thin Film Transistors

An investigation of dielectric permittivity on the sintered high entropy oxide (HEO) capacitor composed of Co, Cr, Fe, Mn, and Ni (i.e., (CoCrFeMnNi)O) developed using solution combustion synthesis is performed. Stabilization of the phase in HEO is extremely important as it has a direct influence on the properties. In order to explore phase stabilization, in-depth studies of thermal, structural, morphological, and compositional analyses are carried out. The optimized processing parameters are further implemented on depositing (CoCrFeMnNi)O dielectric thin films followed by a thin film transistor. Irrespective of the reaction medium, the precursors undergo combustion at a low temperature below 250 °C, resulting in amorphous HEO. Upon crystallization at 500 °C, no secondary impurity oxides were detected and phase-stabilized to a spinel structure (Fd3m). A homogeneous distribution of all five cations without any segregation and a completely disordered occupancy of the cations were displayed by the bulk and thin films of HEOs. The spinel (CoCrFeMnNi)O exhibited high permittivity, with values approximately 7.3 × 102 (in bulk) and 3 × 101 (in a thin film), measured at 1 kHz owing to the entropy stabilization effect of HEO. Due to their high permittivity and low leakage current density (∼10–8 A/cm2), the (CoMnNiFeCr)O thin film was integrated into thin film transistors (TFTs) with molybdenum disulfide-channel. TFTs showed a field effect mobility of 8.8 cm2 V–1 s–1, an on–off ratio of approximately 105, a threshold voltage of −1.5 V, and a subthreshold swing of 0.38 V/dec. The low voltage operation (<5 V) of these TFTs makes solution combustion-derived HEO (CoMnNiFeCr)O a potential candidate in microelectronics and optoelectronics applications.

Neuromyelitis Optica Spectrum Disorders: Clinical Perspectives, Molecular Mechanisms, and Treatments

Neuromyelitis optica (NMO) is a rare autoimmune inflammatory disorder affecting the central nervous system (CNS), specifically the optic nerve and the spinal cord, with severe clinical manifestations, including optic neuritis (ON) and transverse myelitis. Initially, NMO was wrongly understood as a condition related to multiple sclerosis (MS), due to a few similar clinical and radiological features, until the discovery of the AQP4 antibody (NMO-IgG/AQP4-ab). Various etiological factors, such as genetic-environmental factors, medication, low levels of vitamins, and others, contribute to the initiation of NMO pathogenesis. The autoantibodies against AQP4 target the AQP4 channel at the blood–brain barrier (BBB) of the astrocyte end feet, which leads to high permeability or leakage of the BBB that causes more influx of AQP4-antibodies into the cerebrospinal fluid (CSF) of NMO patients. The binding of AQP4-IgG onto the AQP4 extracellular epitopes initiates astrocyte damage through complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC). Thus, a membrane attack complex is formed due to complement cascade activation; the membrane attack complex targets the AQP4 channels in the astrocytes, leading to astrocyte cell damage, demyelination of neurons and oligodendrocytes, and neuroinflammation. The treatment of NMOSD could improve relapse symptoms, restore neurological functions, and alleviate immunosuppression. Corticosteroids, apheresis therapies, immunosuppressive drugs, and B cell inactivating and complement cascade blocking agents have been used to treat NMOSD. This review intends to provide all possible recent studies related to molecular mechanisms, clinical perspectives, and treatment methodologies of the disease, particularly focusing on recent developments in clinical criteria and therapeutic formulations.

Machine learning prediction of venous thromboembolism after surgeries of major sellar region tumors

PurposeTo describe and predict the risk of venous thromboembolism (VTE) after surgical resection of major sellar region tumors. MethodPatients with sellar region tumors were identified from a database. The outcome was VTE, including deep vein thrombosis (DVT) and pulmonary embolism (PE) within 60 days after surgery. We trained regression and machine learning models to predict the outcome using baseline characteristics, surgical findings and postoperative laboratory tests. ResultsAmong 3818 patients included, 124 patients developed VTE after surgery. The total 60-day VTE incidence was 3.2 %, with incidence peak within ten days after the surgery. The risk increased in patients >65 years old (OR 2.96, p < 0.001), in patients with chordoma (OR 3.40, p = 0.006) or craniopharyngioma (OR 1.86, p = 0.036), in patients underwent craniotomy approach (OR 2.78, p = 0.017), in patients with high volume CSF leakage (OR 4.24, p < 0.001), and in patients with longer surgical duration (OR 1.78, p = 0.029). The linear discriminant analysis algorithm had the highest AUC (0.869, 95%CI, 0.840–0.898) in predicting the outcome. The specificity, accuracy, and sensitivity of the best model were 61.8 %, 93.6 %, and 92.8 %, respectively. Risk stratification using our best model suggested that 1.3 % and 24.5 % of the patient developed VTE in the low-risk group and in the high-risk group, respectively. We developed an online decision-support tool available on https://deepvep.shinyapps.io/VTEpred/. ConclusionThe overall incidence of VTE after surgical resection of major sellar region tumors was clinically significant, especially in older patients with chordoma or craniopharyngioma.

Selection principles of polymeric frameworks for solid-state electrolytes of non-aqueous aluminum-ion batteries.

Liquid electrolyte systems of aluminum-ion batteries (AIBs) have restrictive issues, such as high moisture sensitivity, strong corrosiveness, and battery leakage, so researchers have turned their attention to developing high safety, leak-free polymer electrolytes. However, the stability of the active factor of AIB systems is difficult to maintain with most of polymeric frameworks due to the special Al complex ion balance in chloroaluminate salts. Based on this, this work clarified the feasibility and specific mechanism of using polymers containing functional groups with lone pair electrons as frameworks of solid-state electrolytes for AIBs. As for the polymers reacting unfavorably with AlCl3, they cannot be used as the frameworks directly due to the decrease or even disappearance of chloroaluminate complex ions. In contrast, a class of polymers represented by polyacrylamide (PAM) can interact with AlCl3 and provide ligands, which not only have no effect on the activity of Al species but also provide chloroaluminate complex ions through complexation reactions. According to DFT calculations, amide groups tend to coordinates with AlCl2 + via O atoms to form [AlCl2(AM)2]+ cations, while disassociating chloroaluminate anions. Furthermore, the PAM-based solid-state and quasi-solid-state gel polymer electrolytes were also prepared to investigate their electrochemical properties. This work is expected to provide new theoretical and practical directions for the further development of polymer electrolytes for AIBs.

Sliding Mode Controller with Disturbance Rejection for Bidirectional Transformerless AC/DC Converter in EV Onboard Charger

Transformerless power converters are trending in automotive sector as the demand for onboard chargers rises. The high efficiency and leakage current mitigating property of highly efficient and reliable inverter concept (HERIC) converter make it an excellent choice among transformerless topologies. By using appropriate modulation technique, the HERIC converter can transmit bidirectional power. This article presents design of sliding mode controller (SMC) for bidirectional HERIC converter to enhance the tracking performance. The SMC parameters are selected utilizing Harris hawks optimization (HHO) algorithm. During vehicle-to-grid (V2G) operation, sliding mode controller is developed for reactive power regulation of the grid connected HERIC converter and for grid-to-vehicle (G2V) operation, the converter is operated with very low voltage ripples in the DC side. The stability analysis is done by considering model uncertainties to guarantee sinusoidal grid current, low THD, and unity power factor even in the presence of grid disturbances and parametric variations. The Typhoon Hardware in the Loop (HIL) 402 device is used to execute the real-time testing. The results confirmed the efficacy and robustness of the designed controller under different scenarios for both modes of operation.

High-threshold-voltage and low-leakage-current of normally-off H-diamond FET with self-aligned Zr/ZrO2 gate

Normally-off field effect transistor (FET) is highly required for the safe and energy-efficient operation of power switching system. The hydrogen-terminated diamond (H-diamond) FET possesses outstanding properties whereas it usually shows normally on operation. In this paper, high-threshold-voltage and low-leakage-current of normally-off H-diamond FET was achieved via ZrO2/Zr gate fabricated by thermal oxidation (TO) with merits of non-pollution and simple process. The normally-off operation owed to the work function difference between Zr and H-diamond and the positive fixed charge of ZrO2. The X-ray photoelectron spectroscopy results reveal the ZrO2/Zr gate structure and the stoichiometric composition of Zr to O (1:2). The high threshold voltage (−2.7 V) and low drain-source leakage current (10−8 mA/mm) may be attributed to the Schottky barrier of Zr/H-diamond. Additionally, the gate leakage is suppressed by TO-ZrO2. The subthreshold swing, on-off current ratio and gate oxide capacitance per square centimeter are 161 mV/dec, 108 and 0.37 μF/cm2, respectively. These performances demonstrate that the ZrO2/Zr/H-diamond FET would provide an alternative approach for low power H-diamond FET.

A Carrier-Based Low Total Current Ripple Modulation Strategy for Parallel Converters With Leakage Current Attenuation

In order to meet the high performance and low leakage current requirements in high power rating photovoltaic applications, an improved carrier-based modulation (ICBM) for parallel converters is presented in this paper. Different from existing methods which are based on PS-PWM, a proper zero-sequence modulation wave is injected into the three-phase modulation waves to achieve low total current ripple based on the root mean square value analysis of output current ripple. Aside from this, the initial phase shift angles for the carriers in each converter are modified to minimize the excitation source of leakage current, while the quality of total output current is not affected. Furthermore, the proposed ICBM is extended to parallel multilevel converters according to the vector shift principle. By using the proposed ICBM, total current ripple reduction and leakage current attenuation in parallel converters can be achieved simultaneously. Experimental results validated the correctness and effectiveness of the proposed method.

Transformer DGA Fault Diagnosis Method Based on Stacked Sparse Auto-Encoders

In the field of transformer fault diagnosis, the imbalance of fault samples seriously affects the fault identification performance of the diagnosis model. Focusing on the problems of low accuracy and high leakage rate of diagnosis model caused by unbalanced fault samples of transformer, a transformer fault diagnosis method is proposed. First of all, the Borderline SMOTE algorithm is used to balance the fault data set from a few samples on the boundary, so as to achieve the effect of power transformer fault sample equalization. Secondly, a diagnosis model of the stacked sparse auto-Encoders with the gas in oil as input characteristic parameter is built. Finally, an evaluation system consisting of accuracy rate, recall rate and F1 score is selected to compare the diagnosis effect of the model before and after category equalization, the experiment proves the effectiveness of this method.

Comparing different configurations for rotary transformer of wound-rotor resolvers

Wound-Rotor resolvers are the oldest and the most widely used resolvers. They are two-phase synchronous generators with high frequency AC excitation. Rotary Transformers (RTs) are used to supply the rotating excitation winding of the resolver. Although RTs offer the benefits of contactless power transmission, harmonic contents of the secondary voltage, phase shift error between the primary and the secondary voltages, and high leakage flux are the main challenges in their usage along with resolvers. Therefore, in this paper, different configurations are examined for RT’s ferromagnetic core to overcome the mentioned problems. All the simulations are done using 3-D time variant finite element method (TVFEM) and the best configuration is chosen for experimental prototyping and measurements. Close agreement between the simulation and the experimental test results approves the performed analysis.

Integrated Smart Management in WDN: Methodology and Application

Urbanization and population growth have been responsible for a significant increase in consumption of water and energy at a global scale. A careful management of water resource and infrastructures is crucial for Energy Transition, as well as for achieving a sustainable efficiency of these systems. High pressure values along with the ageing of the systems contribute to high leakage levels of Water Distribution Networks (WDN). The simultaneous control of excess pressure and containment of water losses are mainly performed by using Pressure Reducing Valves (PRVs) in WDN, which dissipate the surplus of hydraulic energy. Instead of being dissipated, energy can be recovered by the transformation of the excess pressure into electrical energy with the use of Pump as Turbines (PAT), which results in an increased reliability, reduction of cost and an overall improvement in the efficiency of WDN. The work aims on presenting an integrated efficiency management methodology in terms of Effectiveness (E), capability (ηpi), reliability (μpi) and sustainability (χpi) with values between 47 to 98%, also associated with the pressure and leakage management, and energy recovery. This research presents a modelling of a real WDN of a District Metering Areas (DMA) of Beloura endowed with seasonal consumption variability to better show its applicability. Additionally, an economic analysis to assess the solution’s feasibility is presented concluding an annual energy recovered of 9.8 MWh and a saving of about 30% of water leakage, which correspond, in the analyzed case study, to about 3523 m3. The payback period found is around 9 or 12 years, for only one PAT or two different PATs installed, due to the small available energy of the analyzed case study. Acknowledging the synergy between water and energy efficiency and taking advantage of these integrated smart management methodology exemplification, it resulted in more efficient systems to achieve both effectiveness solutions, digital and energy transition in the water sector.

On the mechanism of turbulent heat transfer in composite porous-fluid systems with finite length porous blocks: Effect of porosity and Reynolds number

The majority of literature studies on composite porous-fluid systems involve fully-developed porous channel flows where the porous media covers the whole length of the channel. These studies utilized periodic boundary conditions at the inlet and outlet. In these systems, the stagnation at the frontal face of the porous block, turbulent separation bubble over the porous-fluid interface, and flow leakage from the porous to non-porous regions do not exist. The existence of these flow features in the case of a finite porous block immersed in a channel flow modifies turbulent interactions across the porous-fluid interface. In contrast to the previous studies, this paper investigates the flow and thermal characteristics of turbulent channel flow containing a porous block with a finite length. To this end, pore-scale large eddy simulations are performed in composite porous-fluid systems with two porosities (53% and 91%) at three Reynolds numbers of 3600, 7200 and 14400. Flow visualization shows that two distinct regions are formed over the interface in low-porosity cases: Region#1 near the leading edge with organised hairpin structures and high flow leakage; Region#2 away from the leading edge with unorganised hairpin structures and lower flow leakage. In region#1, maximum turbulent fluctuations occur far away from the interface while they approach the interface in region#2. The results showed that by increasing either the Reynolds number or porous length, the location of maximum turbulence statistics approaches the interface. This observation supports earlier findings for fully-developed porous channel flows which are only valid in region#2. Whereas, with a low Reynolds number or a short porous length, the turbulent statistics peak far from the interface, consistent with the observations in region#1. Besides, it was found that increasing the porosity and Reynolds number reduces the flow leakage (from the porous region to the non-porous region) up to 50% and 10%, respectively, which in turn disrupts the patterns of contour-rotating vortex pairs and hairpin structures over the interface. It is further found that for a fixed Reynolds number, the overall Nusselt number for the high-porosity case is 2.6 times higher than that of the low-porosity case. The pressure drop for the low-porosity cases is 1.8 times more than that for the high-porosity cases.

A new transformer‐less common grounded five‐level grid‐tied inverter with leakage current elimination and voltage boosting capability for photovoltaic applications

AbstractDue to serious Concerns such as air pollution, global warming, and fossil fuels shortcoming, renewable energy sources such as photovoltaic applications are dramatically being integrated into the power generation systems all of the world. Here, a new switched‐capacitor‐based transformer‐less grid‐tied inverter has been proposed. By applying the series–parallel switching technique of the utilized switched‐capacitor module, the voltage boosting capability has been obtained. By implementing common ground technique, high overall efficiency and leakage current elimination capability have been obtained. Since the proposed inverter provides a multi‐level output voltage, the total harmonic distortion of the injected grid current is reduced. The introduced control strategy has been implemented to control both active and reactive powers and generate the switches pulses. Therefore, a high quality and adjusted current is injected to the grid. This inverter requires a single renewable energy source as input DC source. Here, the comprehensive description of the proposed inverter and its performance with design considerations have been presented. The proposed structure has been compared with several similar structures and the obtained results have been investigated. To evaluate the performance of the proposed inverter, a 620 W laboratory prototype is assembled and experimental results are analyzed.

Schottky contacts on ultra-high-pressure-annealed GaN with high rectification ratio and near-unity ideality factor

We investigate the electrical characteristics of Ni Schottky contacts on n-type GaN films that have undergone ultra-high-pressure annealing (UHPA), a key processing step for activating implanted Mg. Contacts deposited on these films exhibit low rectification and high leakage current compared to contacts on as-grown films. By employing an optimized surface treatment to restore the GaN surface following UHPA, we obtain Schottky contacts with a high rectification ratio of ∼109, a near-unity ideality factor of 1.03, and a barrier height of ∼0.9 eV. These characteristics enable the development of GaN junction barrier Schottky diodes employing Mg implantation and UHPA.

Synthesis and characterization of bismuth ferrite particles using a nano-agitator bead mill

Bismuth ferrite (BiFeO3) nanocomposites were synthesized using a novel nano-agitator bead milling method followed by calcination. Bismuth oxide and iron oxide nanoparticles were mixed in a stoichiometric ratio and milled for 3 h and calcined at 650 °C in air. X-ray diffraction with Rietveld refinement, scanning electron microscopy, and transmission electron microscopy techniques were used to elucidate the structure of BiFeO3. The particle diameter was found to be ∼17 nm. Magnetic and electrical measurements were performed, and these results were compared with those of similar methods. Mostly, BiFeO3 was obtained with minor secondary phase formation. The resulting powder was weakly ferromagnetic with a remnant magnetization of 0.078 emu/g. This can be attributed to residual strain and defects introduced during the milling process. Electrical testing revealed a high leakage current density that is typical of undoped bismuth ferrite.

A bHLH transcription factor, CsSPT, regulates high-temperature resistance in cucumber

High-temperature stress threatens the growth and yield of crops. Basic helix-loop-helix (bHLH) transcription factors (TFs) have been shown to play important roles in regulating high-temperature resistance in plants. However, the bHLH TFs responsible for high-temperature tolerance in cucumbers have not been identified. We used transcriptome profiling to screen the high temperature-responsive candidate bHLH TFs in cucumber. Here, we found that the expression of 75 CsbHLH genes was altered under high-temperature stress. The expression of the CsSPT gene was induced by high temperatures in TT (Thermotolerant) cucumber plants. However, the Csspt mutant plants obtained by the CRISPR-Cas9 system showed severe thermosensitive symptoms, including wilted leaves with brown margins and reduced root density and cell activity. The Csspt mutant plants also exhibited elevated H2O2 levels and down-regulated photosystem-related genes under normal conditions. Furthermore, there were high relative electrolytic leakage (REC), malondialdehyde (MDA), glutathione (GSH), and superoxide radical (O2·−) levels in the Csspt mutant plants, with decreased Proline content after the high-temperature treatment. Transcriptome analysis showed that the photosystem and chloroplast activities in Csspt mutant plants were extremely disrupted by the high-temperature stress compared with wild-type (WT) plants. Moreover, the plant hormone signal transduction, as well as MAPK and calcium signaling pathways were activated in Csspt mutant plants under high-temperature stress. The HSF and HSP family genes shared the same upregulated expression patterns in Csspt and WT plants under high-temperature conditions. However, most bHLH, NAC, and bZIP family genes were significantly down-regulated by heat in Csspt mutant plants. Thus, these results demonstrated that CsSPT regulated the high-temperature response by recruiting photosynthesis components, signaling pathway molecules, and transcription factors. Our results provide important insights into the heat response mechanism of CsSPT in cucumber and its potential as a target for breeding heat-resistant crops.