Large Leakage Research Articles

Ferroelectric Domains Engineering in 2D Van Der Waals Ferroelectric α‑In2Se3 Via Flexoelectric Effect.

2D) Van der Waals ferroelectrics offer the opportunity for developing novel nanoelectronics devices. For device applications, it is necessary to generate controllable ferroelectric polarization domains and achieve non-destructive polarization switching. However, it is very challenging to use the electric field to manipulate the domain state of ultra-thin ferroelectric film due to the large leakage current and even electric breakdown. Here, the flexoelectric effect on the manipulation of polarization states at bending α-In2Se3 flakes is explored via piezoresponse force microscopy (PFM). By introducing patterned Si trench substrates, the stripe micron-scale ferroelectric domains with alternating arrangements of the out of-plane polarization in the curved α-In2Se3 are observed. It is found that the polarization at the bending region of α-In2Se3 can be directly reversed by the large flexoelectric field. The controllable mechanical modulation of α-In2Se3 ferroelectric domains opens up potential applications of ferroelectrics in strain engineering functional devices.

Design and Improvement of Curved Envelope Meshing Pair Profile of Single Screw Compressor

Abstract In recent years, the wear problem of the wheel tooth in the single screw compressor (SSC had been solved due to the development and application of various envelope profiles. Among these profiles, the curved envelope profile shows performance advantages, which displays great application potential in the fields of high-temperature heat pump, steam compression, etc. However, SSC with curved envelop profile still faces the problem of incomplete design method, large leakage clearance, difficult processing and meshing pair interference under extreme conditions. Therefore, aiming at solving these problems, a coupling profile design method for the curved envelope meshing pair of the SSC was presented and studied. The profile equation of curved envelop meshing pair of a SSC with an ellipse profile as the characteristic line was established. The method of using standard tooth width was proposed for the quick geometric design of the SSC. The coupling profile design of the star wheel tooth angle and the groove bottom angle with variable diameter circular arc was invented. The equation of the transition arc surface of the bottom angle of the groove and the angle of the star wheel tooth was derived. It provided a theoretical basis for the design and improvement of meshing pair with curved envelop profile.

Ultralarge Hyperpolarizability, Novel Ladder‐Type Heteroarenes Electro‐Optic Chromophores: Influence of Fused Heterocyclic π‐System and Push–Pull Effect on Nonlinear Optical Properties

ABSTRACTA new series of ladder‐type heteroarenes electro‐optic (EO) chromophores based on unique fused oligothiophene, oligofuran, and oligopyrrole bridge with a strong push–pull effect were designed, and their distinctive electric structure and nonlinear optical (NLO) properties were investigated by multiple methods, including DOS analysis, CPKS method, SOS model, TSM model, and hyperpolarizability density analysis. Interestingly, it is found that the introduction of different strengths of donor and acceptor moieties, the nature of ladder‐type heteroarenes bridge, and the medium polarity play critical roles in achieving ultra‐large hyperpolarizabilities. Encouragingly, the DN1‐6Fu‐AS1 and DN1‐6Py‐AS1 both exhibit ultra‐large βprj values (up to 12965.5 × 10−30 esu) and βtot value (up to 13238.2 × 10−30 esu), owing to their exceptionally low transitions energy and large variation of dipole moment. The DO2‐6Fu‐AO2, DO2‐6Th‐AO2, DO2‐6Fu‐AS1, and DO2‐6Th‐AS1, exhibit very deep HOMO levels, which are expected to have superior air stability and effectively prevent large leakage currents. Hirshfeld surface analysis and interaction region indicator analysis were employed to explore the noncovalent interactions in the dimer. The DO2‐6Fu‐AS1 and DO2‐6Py‐AS1 show the outstanding electro‐optical Pockels effect, and DN1‐6Fu‐AO2 exhibit large SHG responses. These unique and brand‐new push‐pull ladder‐type heteroarenes chromophores are promising candidates for chip‐scale EO modulators, and electronic and photonic devices in emerging communication, energy, analog, and digital technologies.

Study of thermal annealing on gallium oxide heteroepitaxial layers grown on SiC for vertical Schottky barrier diodes applications

This study successfully grew ꞵ-Ga2O3 epitaxial films on silicon carbide substrates by metalorganic chemical vapor deposition and fabricated vertical Schottky barrier diodes (SBDs), which were annealed in a high temperature furnace. The high surface roughness and oxygen vacancies of the unannealed device caused a large leakage current, thus three different annealing durations were used to repair the surface oxygen vacancies in an O2:N2=1:4 gas environment. The results showed that a 5-minute thermal annealing process was the most effective in repairing surface oxygen vacancies. According to the X-ray photoelectron spectroscopy spectra of the O 1 s core levels in Ga2O3 epilayers, the proportion of oxygen vacancies decreased from 56.56 % to 49.71 %. Additionally, the leakage current density was decreased from 10−3 to 10−5 A/cm2 and the surface roughness decreases to 32.6 nm due to stress release. Furthermore, the barrier heights (φb) of the SBDs without annealing, and after annealed for 5, 20, and 40 min were measured at 0.911, 1.229, 1.090, and 1.115 eV, respectively. It was observed that the SBD fabricated on the epilayer annealed for 5 min exhibited the lowest leakage current (approximately 2 × 10⁻⁵ A/cm²) and the highest breakdown voltage, measuring around 132 V.

High-performance cold-source field-effect transistors based on Cd3C2/ boron phosphide heterojunction

To overcome the short-channel effect and large gate leakage current in the field-effect transistors (FETs), some cold-source materials have been suggested as alternative materials. We explore the performance of FET based on the cold-source material Cd3C2 using the ab initio quantum transport method. It is shown that the figure of merits (FOMs) of Cd3C2/ Boron phosphide (BP) FET satisfies the requirements of ITRS2028 HP for UL=2 and UL=3nm. The performance of Cd3C2/BP FET is improved when Cd3C2 is p-type doped. Doping causes a super-exponential decrease in carrier concentration, thus the cold-source FET based on Cd3C2/BP is formed. When the doping concentration reaches 10.0 × 1013cm−2, the device satisfies the requirements of ITRS2028 HP. More importantly, at the doping concentration of 10.0 × 1013cm−2 for UL=2 and 3 nm, the subthreshold swings are 52.32 and 56.84 mV/dec, which are lower than 60 mV/dec. This work proposes a new cold-source FET based on Cd3C2/BP, whose excellent performance can make it a competitive candidate in future electronic devices.

Super High-k Unit-Cell-Thick α-CaCr2O4 Crystals.

High-dielectric-constant (high-k) insulators are indispensable components to integrate semiconductors into metal-oxide-semiconductor field-effect transistors with sub-10 nm channel length, where the equivalent oxide thickness (EOT) of high-k insulator needs to be decreased to subnanometer scale. The traditional insulators, including Al2O3, SiO2, and HfO2, fit well with the existing silicon industry but suffer from serious degeneration of insulating properties, such as large leakage currents caused by high-density borders and interface traps, when their thicknesses are reduced to a few nanometers. Here, we synthesize a high-quality nonlayered ultrathin α-CaCr2O4 crystal down to unit-cell thickness (∼1.2 nm) by an elements slow-supply chemical vapor deposition (CVD) method. The unit-cell-thick α-CaCr2O4 crystals show a super high dielectric constant of 87.34, which is over 20 times higher than that of well-known layered insulator h-BN and corresponds to an EOT below 1 nm. Furthermore, it has a high breaking strength (39 GPa) and excellent stability. This strategy can also be used to fabricate other ultrathin ternary oxides, such as high-k ultrathin FeNb2O6 crystals, demonstrating the universality of the CVD method.

Advancements to generalized equivalence theory for preserving cross-sections of whole core simulations

The conventional two-step approach, without the use of an equivalence method, can introduce significant error for the simulation of non-LWRs (Light Water Reactors), especially fast reactors, due to the large leakage and high anisotropic neutron distribution. To improve upon the accuracy of the two-step approach, a 3D whole core model is simulated with a transport method to generate region-wise homogenized cross-sections (XS). These XS can then be used in a diffusion whole core solver during the second step to extend the application to cycle and transient analysis. Discontinuity factors (DFs) are then introduced to improve the accuracy during the simulation of the second step. With properly generated DFs from Generalized Equivalence Theory (GET), the region-averaged solutions from the first transport step can then be reproduced by the second step diffusion solver. The Monte Carlo method was selected to perform the whole core transport simulation to generate region-wise XS. However, simulating whole core problems with Monte Carlo may result in poor statistics near the peripheral region especially for partial current tallies. This paper introduces an advancement to GET to reproduce region-wise solutions for select regions when the reaction rates and surface currents have good statistics in these regions but poor statistics in other regions. A reference high-fidelity model was constructed using the Serpent 2 Monte Carlo code based on the EBR-II benchmark evaluation and verification was carried out using the TriPEN-4 method in PARCS. The results show that it is possible to reproduce the exact eigenvalue and power distributions of whole core problems in a feasible manner.

Probabilistic safety analysis of the large primary circuit leakages accident scenarios in the VVER-reactor

Probabilistic safety analysis of the loss of coolant accidents in the VVER-type reactor plant has been performed taking into account the internal initiating events of the reactor primary circuit large leakages. Swedish program code RiskSpectrum PSA was used for probabilistic safety analysis. Logical probabilistic models of the accident scenarios of the large primary circuit leakages in the VVER-type reactor were developed taking into account different operation modes of the power plant unit. Critical paths and probabilities of the accident scenarios occurrence of the large leakages were identified. The critical path of development of the reactor primary circuit large leakages accident with large leakages of 140–346 mm diameters is the accident sequence with a leak in the pipeline to the reactor pressurizer vessel. It has been established that the greatest contribution to the failure of safety functions during this initiating event is made by the failures due to common causes of the supporting systems (cooling and ventilation systems), critical consumers cooling circuit, emergency injection system. The critical path of the accident with large leakages of 346–850 mm diameters is the accident sequence with the rupture of any of the four primary circuit loops. The greatest contribution to the failure of safety functions during this initiating event is made by the failures due to common causes of the emergency injection system elements. Based on the accident analysis, recommendations for increase of performance reliability of safety functions during the large leakages accidents under all operation states of the nuclear power plant unit were given. In order to increase reliability of safety systems, it is necessary to eliminate failures due to common causes of equipment, increase the reliability of operation of supporting systems, change the maintenance and checking equipment procedures.

Multiphase soft metal enabled high-performance fabric-based wearable energy harvesting

Highly efficient and flexible power sources have always been the focus and goal in the field of wearable electronics. However, the existing wearable power sources are limited by their large size, high weight, electrolyte leakage, and poor mechanical compliance, which seriously hinders their practical applications. Herein, we propose a novel strategy to achieve and demonstrate a fabric-based high-performance wearable triboelectric nanogenerator (TENG) structure. The metals of gallium (Ga), bismuth (Bi), indium (In), and tin (Sn) are mixed according to specific mass ratios, and then they are transformed in liquid phase to form room-temperature multiphase soft metals of GaBiInSn. The material exhibits both metallic and fluidic properties, and possesses a characteristic of multiphase structure. The GaBiInSn material is directly deposited between polytetrafluoroethylene (PTFE) layers and nonwoven fabrics to establish multi-level conductive and frictional interfaces, creating charge transfer and solid-liquid hybrid dielectric layers. Therefore, the thin film-type triboelectric nanogenerators with a structure of PTFE/GaBiInSn/nonwoven fabric (LM-P-TENGs) is manufactured. The LM-P-TENGs can be integrated onto fabrics without compromising their breathability, comfortableness, and flexibility. Particularly, LM-P-TENGs efficiently convert the mechanical energy of human limb movements into sustainable electrical energy output. Under the human limb mechanical triggering conditions, LM-P-TENG achieves a champion specific open-circuit voltage up to 900 V, peak short-circuit current density of 43.3 mA/m2, and high power density of 12.56 W/m2. This work demonstrates the application potential of room-temperature multiphase soft materials in flexible wearable power sources, while introducing a novel power supply mode for wearable electronics. Additionally, the LM-P-TENGs also present applications in self-powered wearables, medical biosensing systems, human-machine interaction systems, near-eye display systems, etc. for the flexible electronics.

Experimental Investigation on Leakage and Frictional Heat Generation Characteristics of Low Hysteresis Brush Seals

Abstract Low hysteresis brush seals are frequently used in systems operating at a high speed in environments featuring a high temperature and pressure. The high-speed rotor comes into contact with the bottom end of the bristles of the brush seal in such scenarios to generate a significant amount of frictional heat, which directly affects its sealing performance and service life, while a high temperature can increase the magnitude of its friction-induced heat. In this study, we report the cyclical testing of a low hysteresis brush seal while increasing and decreasing the speed of the rotor under varying differences in the pressure and temperature. We focus on the characteristics of leakage, hysteresis effect, and temperature rise at the bottom end of the bristles of the brush seal owing to frictional heat. The results showed that the volume of leakage increased at a high temperature under a strong hysteresis effect and a small rise in the temperature. Moreover, as the speed of the rotor exceeded 6000 rpm, the temperature of the system increased rapidly owing to frictional heat. During the speed decrease stage, the temperature rise decreased sharply and then gradually until it became nearly constant. The hysteresis effect resulted in a lower temperature rise during the decrease in the speed of the rotor compared with that during an increase in its speed. While the low hysteresis structure can effectively reduce hysteresis effect compared with that of the conventional brush seal, it induced greater leakage. It is necessary to choose a pressure relief chamber of a suitable size to minimize leakage. Furthermore, the low hysteresis brush seal exhibited a smaller friction temperature rise than the conventional seal, where this is beneficial for its service life.

379. SUCCESSFUL MANAGEMENT OF ANASTOMOTIC LEAKAGE FOLLOWING ESOPHAGECTOMY USING ENDO-VACUUM ASSISTED CLOSURE (EVAC) THERAPY: A CASE REPORT

Abstract Background Esophagectomy is a crucial curative treatment for potentially resectable esophageal cancer. However, anastomotic leakage poses a significant complication, with reported incidences ranging from 11.4% to 21.2% and mortality rates between 7.2% and 35%. Endoluminal or cavitary type of vacuum therapy (EVAC) represents a minimally invasive approach adapted from negative pressure wound closure techniques. Our case demonstrates the successful application of EVAC in managing a significant postoperative leak. Methods A 70-year-old male who underwent esophagectomy for early esophageal cancer. On postoperative day 23, a 20mm-sized large anastomotic leakage was detected, leading to the insertion of Endo-VAC for treatment. Endoscopically exchange was regularly. Results Endoscopically exchange was performed seven times, gradually reducing the size of the leakage hole. In the end, the anastomotic leakage was completely healed, and the patient was discharged on postoperative day 86. The patient id currently undergoing outpatient follow-up with no recurrence or metastasis of the disease confirmed. Conclusion Through our case, we highlight the potential suitability of EVAC therapy as a less invasive and effective treatment modality for anastomotic leakage following esophagectomy. This approach may be considered as a priority treatment for anastomotic leak.

Research on lubrication mechanism of plunger pair considering viscosity temperature and pressure effect

Aiming at the key problems such as serious friction and wear and large leakage of aviation piston pumps operating under high-speed and high-pressure harsh conditions, the lubrication characteristics of aviation plunger pumps are studied in this paper. In order to improve the lubrication performance of the plunger pump, as well as its working efficiency and service life, the equations of pressure, the thickness, and the leakage of the plunger pair oil film under the combined actions of viscosity temperature and pressure under pressure flow, shear flow, and cylinder elastic deformation are established. The finite difference method is used to analyze the lubrication characteristics and the leakage of the plunger pair under these four different conditions: considering, respectively, the effect of viscosity temperature and pressure, only considering the effect of viscosity temperature or viscosity pressure, without considering the effect of viscosity temperature and viscosity pressure. As a result, coupled by the effects of viscosity temperature and viscosity pressure, when the temperature increases from 20 to 60 °C, the oil film pressure increases, and the thickness decreases faster. When the temperature increases from 60 to 120 °C, the oil film pressure increases and the thickness decreases slower When the contact length of the plunger pair increases from 17 to 37 mm, the leakage ratio decreases more rapidly, and when it is greater than 37 mm, it decreases more slowly. The following conclusions were obtained: the viscosity of lubricating fluid is greatly affected by temperature and pressure. The viscosity decreases and increases hyperbolically with the increase in temperature and pressure, the maximum oil film pressure when considering the effect of viscosity temperature and pressure was significantly greater than that without considering the viscosity temperature and pressure, and the minimum oil film thickness was much smaller than that without considering the viscosity temperature and pressure. The leakage curve when considering the viscosity temperature and pressure effect was obviously different from when only considering a single factor or not considering the viscosity temperature and pressure effect. The magnitude of leakage in the four cases is: considering the viscosity temperature effect, considering the viscosity temperature and pressure effect, not considering the viscosity temperature and pressure effect, and considering the viscosity pressure effect. This study can provide a reference for the accurate theoretical design and safe and stable operation of the plunger pair in the plunger pump.

Resolving sustainable development conflicts caused by vinyl leakage accidents in the USA: From the perspective of graph model under fuzzy preferences with self-confidence

On February 3, 2023, a railroad accident led to the release and combustion of 115,580 gallons of vinyl chloride monomer in East Palestine, Ohio, USA. The large leakage and long-time combustion of vinyl chloride monomer harmed the stability of local sustainable ecosystems and the health of residents, as the burning produced deadly toxins, triggering dissatisfaction from residents and environmental protection organizations. With the COVID-19 pandemic still unfolding globally, decision makers (DMs) in vinyl chloride leakage accidents must consider the existing environmental health uncertainty, potentially leading to uncertainty in their preference cognitive. Thus, this paper proposes a novel fuzzy preference with a self-confidence structure of the graph model for conflict resolution (GMCR) to resolve the sustainable development conflicts caused by the vinyl chloride leakage accident in Ohio. Fully considering the uncertainty of option choice by DMs and the different levels of confidence in DMs’ preference selection, four different fuzzy stability definitions of self-confidence are defined in GMCR. The analysis results suggest the following: (1) During conflicts, the US Norfolk Southern Corp should assume corporate responsibility by setting up a health monitoring system for residents in Ohio; the company should pay for the medical examinations and related care expenses for residents within the scope of the vinyl chloride leakage accident. (2) The negotiation of all stakeholders in conflicts can promote reconciliation. Finally, the analysis process and results of this study can provide guidance to government departments for properly handling major accidents and appeasing affected residents.

Influence mechanisms of ultraviolet irradiation aging on DC surface discharge properties of silicone rubber in dry and humid air

In the modern DC electrical transmission system, high-energy photons interact with silicone rubber (SIR) chains during long-term ultraviolet (UV) irradiation, it degrades the surface properties and triggers surface discharge (flashover) along the SIR-air interface, threatening the secure operation of the advanced electrical equipment. To further comprehend how UV-aging influences the flashover performance, in this work, the chemical bonds, surface charge transport parameters, and flashover performance of UV-aged SIR samples are characterized, and the influence mechanisms of UV-aging on surface discharge in dry and humid air are comprehensively clarified through the investigation from “molecular-mesoscopic-macroscopic” scales. The results indicate both degradation and oxidization reactions occur during UV-aging. The degraded molecular chains dominate the discharge in dry air, while oxidization reactions determine the discharge in humid environment: The degradation reactions reduce the surface trap depth and increase surface conductivity, leading to large surface leakage current and surface charge dissipation rate, causing flashover voltage in dry air increases and decreases as UV-aging time increasing. The oxidization of the chains introduces –OH and –COOH groups into chains, enhancing permittivity and adsorbing H2O molecules, significantly increasing surface leakage current, causing surface discharge voltage in humid air to decrease as UV-aging time increases.

Phase and defect structures of MnO2‐doped 75BiFeO3–25BaTiO3 ceramics and their effects on electrical properties

AbstractBismuth ferrite (BiFeO3)‐based high‐temperature piezoelectric ceramics have high Curie temperatures and excellent thermal stability; however, their applications are limited by inadequate piezoelectric performance due to large coercive fields and high leakage conduction. This study investigates the impact of MnO2 doping on the phase transition, defect structure, domain morphology, as well as the dielectric, ferroelectric, and electrical conduction behaviors of 75BiFeO3–25BaTiO3 ceramics sintered under an oxygen atmosphere. A structural transformation from distorted rhombohedral to pseudo‐cubic symmetry was observed with increasing MnO2 content, accompanied by domain fragmentation. MnO2 doping at an appropriate level inhibited defects such as and . Regarding electrical properties, the reduction in rhombohedral distortion and enhancement in the pseudo‐cubic phase after MnO2 doping resulted in decreased remanent polarization and electrostrain, which could potentially hinder piezoelectric response. However, appropriate MnO2 doping effectively reduced leakage conduction, significantly enhancing the poling efficiency of the ceramics. The maximum d33 value of 107 pC/N and kp of 0.36 were achieved at an MnO2 doping content of 0.1 wt.%. Excessive MnO2 addition may generate defect dipoles, as indicated by increased coercive field (Ec) and dielectric loss. The observed increase in high‐temperature resistivity with MnO2 content is primarily attributed to reduced grain size and increased concentration of mobile defects. This study provides valuable insights for further research on the application of 75BiFeO3–25BaTiO3 systems in high‐temperature piezoelectric devices.

Enhancement of ferroelectric properties of the Ga0.6Fe1.4O3 films by Zn,N co-doping

Multiferroic materials have attracted considerable interests due to their scientific and technological importance in advanced devices. Ga0.6Fe1.4O3 thin film exhibits ferrimagnetism above room temperature but suffers from large leakage current. To reduce the charge conduction and enhance the ferroelectric properties of Ga0.6Fe1.4O3 film, ion doping is a useful technique. In this study, we fabricated Ga0.6Fe1.4-xZnxO3/N films by substituting Zn2+ and N3- ions in Ga0.6Fe1.4O3 for Fe and O, respectively. The influence of Zn, N co-doping on the structure, leakage current, magnetic and ferroelectric properties of the films were investigated. The results indicated that the films exhibited the orthorhombic structure with the incorporation of Zn and N. All Ga0.6Fe1.4-xZnxO3/N films showed above room temperature ferrimagnetism, and the magnetization and transition temperature values decreased with Zn,N co-doping. The microscopic and macroscopic ferroelectric measurements have demonstrated the ferroelectric polarization switching of the films. The ferroelectric hysteresis loops of the Ga0.6Fe1.38Zn0.02O3/N film showed the remnant polarization of ∼0.46 μC/cm2 with the coercive field of ±2 V at room temperature. The leakage current significantly reduced from ∼3.27×10−1 A/cm2 for pure Ga0.6Fe1.4O3 film to ∼1.48×10−5 A/cm2 for Ga0.6Fe1.35Zn0.05O3/N film, by four orders of magnitude. This may be attributed to the incorporation of Zn2+ and N3-, providing charge compensation to valence fluctuations of Fe between Fe3+ and Fe2+. These results provide an effective method to improve the ferroelectricity of Ga0.6Fe1.4O3 film, and open a wide perspective for the potential application in magnetoelectric devices.

Research on Leak Detection of Low-Pressure Gas Pipelines in Buildings Based on Improved Variational Mode Decomposition and Robust Kalman Filtering.

Aiming at the complex characteristics of negative pressure waves in low-pressure pipelines inside of buildings, we proposed an estimation method of pressure fluctuation trends based on the robust Kalman filter and the improved VMD, which can be used for leakage detection. The reconstructed baseline signal can accurately describe the fluctuation trend of the negative pressure wave after the pressure drop, and quantitatively express the characteristic difference between the leakage condition and the gas usage condition. The robust Kalman filter was used to estimate the pressure fluctuations. The parameters of VMD were adaptively calculated based on the WAA and discrete scale space. The trend components contained in the IMFs were separated by a reconstruction based on the Fourier series. Based on the simulation signal, the method can accurately restore the trend component contained in the complex pressure signal. Based on the actual signals, the accuracy of small leakage detection is 96.7% and the accuracy of large leakage detection is 73.3%.

Exploring the long-term impact of a cadmium pollution accident on microbial communities in river ecosystems

The large leakage accidents of heavy metals from industrial facilities pose a serious environmental problem; however, not enough studies have been conducted to assess the long-term ecological risk associated with such accidents. This study evaluated changes in the bacterial communities within river sediment and identified the key functional microorganisms responding to the 2012 cadmium contamination incident in the Long River, Guangxi Province, China. Results revealed that after a prolonged period of pollution accidents, cadmium pollution still had a discernible effect on the bacterial communities of the river sediment. In comparison to the control site (S1), the bacterial α-diversity in sediments from the accident area (S3) and its downstream (S5) showed a significant increase following the incident. In the control site, Burkholderiaceae was dominant, while in S3 and S5, Pedosphaeraceae, Nitrosomonadaceae, Nitrospiraceae and Geobacteraceae were significantly increased. Sulfur bacteria were found to be more responsive to this cadmium contamination than other bacteria. At site S3, the abundances of Sulfuricurvum, Sulfurifustis, Thioalkalispira, Desulfobacteraceae and Desulfarculaceae were hundreds of times higher than at site S1, indicating an intensification of sulfur cycling processes. The functional prediction implied that cadmium pollution may promote methane oxidation coupled with sulfate reduction reactions and altered the processes of nitrification and denitrification. Environmental factors influencing the microbial community included the levels of metals (cadmium, arsenic, iron) in sediment, as well as other sediment characteristics like temperature and electrical conductivity. These findings contribute to our understanding of the long-term ecological consequences of environmental pollution in river ecosystems.Graphical abstract

Optimization of deep acid fracturing parameters for Shunbei carbonate dissolved fault reservoirs

Abstract When encountering favorable reservoirs that have not been drilled along the wellbore trajectory of Shunbei carbonate fracture-cavity reservoirs, deep acid fracturing technology is required to communicate with favorable reservoirs and achieve production. Currently, there is no optimized method for designing deep acid fracturing parameters for Shunbei fracture-cavity reservoirs, which results in problems such as failure to communicate with favorable reservoirs after deep acid fracturing or rapid decline in production after communication. To address these issues, this paper establishes a geological feature model for fracture-cavity reservoirs based on the characteristics of Shunbei fracture-cavity reservoirs and proposes a deep acid fracturing fracture parameter optimization approach with production capacity as the goal. Using a multi-field coupled acid fracturing model that can reflect the large leakage characteristics of fracture-cavity reservoirs, the proposed fracture parameters are used to simulate and optimize the scale of pre-flushing liquid and acid liquid. The simulation results show that the desired increase in production can be achieved when the fracture diversion capacity is 30D·cm and the penetration ratio is between 0.1 and 0.3. Furthermore, this paper recommends injecting 450~900 m3 of pre-flushing liquid to communicate with favorable reservoirs (0.1≤De≤0.2), followed by the injection of 900 m3 of cross-linked acid and 450 m3 of gelled acid to construct the fracture diversion capacity through acid corrosion.

Enlargement of effective area in Schottky barrier diodes on heteroepitaxial (001) diamond substrates by defect reduction and their radiation tolerance

A major obstacle to realizing diamond electronics is the presence of device-killing defects. Characteristics of diamond-based diodes are degraded with increasing contact size, and a large Ohmic-like leakage current can be generated. Here, we introduced a buffer layer to suppress the killer defects, which extended from the substrate to the epitaxial layer. With the utilization of the buffer layer created using the metal-assisted termination (MAT) technique, Schottky barrier diodes (SBDs) with diametric sizes of Schottky contact ranging from 65 to 1000 μm were fabricated on heteroepitaxial-grown diamond (001) substrates. The SBDs exhibited an explicit rectifying behavior with a rectification ratio of >1010 even with 1000 μm circular contact (7.85 × 10−3 cm2). Satisfying diode parameters were obtained with an ideality factor of 1.52, a Schottky barrier height of 1.66 eV, and a picoampere of leakage current at a reverse bias of 10 V. Interestingly, the diode parameters of the diamond-based SBDs such as ideality factor, Schottky barrier height and rectifying ratio were likely not changed or degraded even after absorption to 1 MGy in the dose of white X-ray. Overall, this demonstration indicates a promising way to realize a large active area of diamond electronics that is applicable to high-output power transmission devices and detector applications.