Cutoff Condition Research Articles

Design of Li-Si Alloy Anodes for Enhancing Mechanical Stability and Electrochemical Performance of Sulfide-Based All-Solid-State Batteries

Li metal all-solid-state batteries, valued for their higher energy density and stability, face issues with lithium metal anodes, such as dendrite structures formation. To address these issues, alloy-based anodes such as Si, Al, and In are replacing lithium metal due to their high-capacity and lithiophilic characteristics. However, there is an issue of large volume change (~300 %) in the alloy anodes during the charge-discharge cycling Pre-lithiation, is considered one of the effective solutions to mitigate volume expansion in the alloy anode. In the present study, we prepared full cells consisting of LixSi (x = 1, 1.7, 2.3, 3.25, 4.4) anodes, argyrodite (Li6PS5Cl) electrolytes, and sulfur composite cathodes, to study the effect of the lithium concentration on the mechanical stability as well as electrochemical performance of sulfide based all-solid-state batteries. During the charge-discharge cycles, we measured the voltage profiles and electrochemical impedance spectra using an embedded Indium reference electrode. Microstructure of the solid electrolyte and distribution of lithium ions were analyzed using secondary electron microscope (SEM) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). High lithium concentrations (LixSi, x = 3.25, 4.4) exhibited high areal capacity ( ~ 3.5 mAh/cm2), however the non-uniform deposition of lithium on the anode surface during alloying led to the formation of lithium dendrite structures. For a low lithium concentration, LiSi demonstrates limited capacity due to a low lithium-ion diffusion coefficient. The medium concentration, Li1.71Si, showed comparable areal capacity to that of high lithium concentration and maintained high stability even under high cut-off voltage condition without dendrite formation. Thus, this study indicates that the medium lithium concentration (x = 1.71) alloy anode provides superior chemo-mechanical stability as well as comparable areal capacity, to the high lithium concentration (x = 3.25, 4.4).

How Fast Charging Affects Manganese Spinel Structure

Lithium-ion batteries have transformed the market of portable electronics and electric vehicle due to their high energy density and efficiency. Positive electrode materials play a critical role in determining the performance and stability of Li-ion batteries. LiMn2O4 (LMO) and LiNi0.5Mn1.5O4 (LMNO) are important positive electrode materials known for their valuable electrochemical properties.1 LMO, a manganese-based spinel, exhibits low cost and high working potential, making it attractive material for consumer electronics.3 On the other hand, LMNO, which incorporates nickel into the manganese spinel structure, offers enhanced specific capacity and cycling stability, making it a potential candidate for high-energy applications such as electric vehicles.4,5 This study investigates the impact of fast charging on the structure of spinel-based positive electrode materials, focusing on LMO and LMNO representatives. Fast charging is achieved using the constant current constant voltage (CCCV) method, a common technique in Li-ion battery charging protocol characterized by an initial constant current phase followed by a constant voltage phase. We investigated samples charged at 2C, 5C and 10C-rate current as well as different voltage cut-off conditions. Ex situ Raman mapping, X-ray diffraction (XRD) and scanning electron microscopy (SEM) are employed to assess structural changes and possible impurity formation during the fast charging processes. Raman mapping is very sensitive on local structural changes and gives detailed insights into electrode composition with good statistics. By probing vibrational modes associated with spinel structures, the technique provides spatially resolved data on phase distribution and impurity formation. XRD complements this analysis by providing bulk structural information, including lattice parameters and crystallographic phase changes induced by fast charging. The combined application of these techniques allows a comprehensive understanding of the electrode's response to harsh charging conditions. This study underlines the importance of investigating structural stability and highlights the utility of readily available and very capable techniques, including Raman mapping and XRD, in explaining the mechanisms behind performance decline and capacity loss in Li-ion battery electrodes subjected to fast charging. An in-depth understanding of structural changes under fast charging conditions, especially in view of the growing fast charging infrastructure, is crucial for the advancement of battery technology.This work was funded by the National Center for Science in Poland through the Sonata BIS 11 programme (No. UMO-2021/42/E/ST5/00390). Marcus Fehse et al. Chem. Mater. 2022, 34, 14, 6529–6540Burak Aktekin et al. ACS Appl. Energy Mater. 2019, 2, 5, 3323–3335Francesco Paparoni et al. J. Phys. Chem. C 2023, 127, 18, 8649–8656Jinfeng Zeng et al. ACS Appl. Energy Mater. 2024, 7, 6, 2405–2415Nicholas P. W. Pieczonka et al. Phys. Chem. C 2013, 117, 31, 15947–15957

X-Ray Computed Tomography Evidence for Minimal Li-Metal Expansion during High-Rate Discharge in High-Energy Li|NMC811 Pouch Cells

Lithium (Li) metal batteries (LMBs) hold great promise in energy storage, offering high energy densities surpassing 350 Wh kg⁻¹ at the cell level.[1] However, their widespread adoption faces significant hurdles, including inefficient Li plating/stripping, low Coulombic efficiency, short cycle life, and dendrite formation. To address these challenges and enable the practical implementation of high-energy-density LMBs, a comprehensive understanding of degradation mechanisms affecting Li metal electrodes is crucial. Yet, the intricate degradation mechanisms of Li metal electrodes remain elusive, particularly regarding the impact of charge/discharge rates, which are essential for various practical applications. While several studies have extensively explored the influence of charging rates on LMB performance, the effect of discharging rates remains unclear.[2] Additionally, in high-energy-density cell designs, the Li metal electrode is prone to damage during disassembly, highlighting the importance of non-destructive techniques for accurate degradation assessment.This study investigates the impact of discharging rates on the degradation of Li metal electrodes in pouch-type cells with cell-level energy densities exceeding 350 Wh kg⁻¹.[3] Leveraging X-ray computed tomography (XCT) analysis as a non-destructive technique, three-dimensional structural information was obtained without sample damage. XCT analysis revealed substantial volume expansion of the Li electrode during charge/discharge cycles, especially under high-rate charging conditions. The repeated cycles induce unwanted side reactions between Li metal and the organic electrolyte, forming an electrically insulating solid-electrolyte interphase (SEI) layer on the electrode surface. Additionally, trapping of the limited amount of electrolyte (2 g Ah⁻¹) within the electrode pores exacerbates impedance growth and uneven current distribution. Interestingly, XCT observations, as shown in Figure 1, indicate suppressed volume expansion of Li during high-rate discharge, resulting in reduced impedance increase and improved cycle life. However, discharge rates beyond a threshold lead to declining capacity retention due to inefficient Li kinetics, amplifying discharge overpotential and prematurely reaching cut-off conditions. This study identifies an intermediate discharge rate offering superior cycle life, elucidating the interplay between Li electrode stability and kinetic constraints in high-energy-density LMBs under ultra-high discharge current rates. These insights hold substantial implications for advancing practical applications of high-power and high-energy LMBs.

Impact of cut-off frequency effect on resonance energy transfer and Casimir–Polder interaction

Abstract Using the Green’s function approach, we investigate the resonance energy transfer (RET) rate between two parallel, identical two-level atoms in the presence of three types of cylindrical system: a distributed Bragg reflector (DBR), a perfectly reflecting wall (PRW), and a two-layer silicon fiber. Our analysis, incorporating the cut-off frequency condition, reveals significant suppression of the RET rate for atoms positioned along the axis of the cylinder with the PRW. In contrast, for atoms located within the DBR, the RET rate is enhanced in the far zone. Additionally, we find that for atoms oriented radially are placed inside or near the surface of the silicon fiber, the RET rate is entirely inhibited. We also investigate the Casimir–Polder (CP) interaction between a cut-off-frequency DBR and an excited atom, discovering a fully attractive potential towards the surface for the atom within the waveguide.

Improving the physiological properties and yield of safflower by combining organic and chemical nitrogen in different irrigation cut-off conditions

The purpose of this work was to investigate how different nutrition systems (N0: 0:0, N1: 100:0, N2: 75:25, N3: 50:50, N4: 25:75, and N5: 0:100 kg ha−1 nitrogen from urea and organic fertilizer sources respectively) affect the physiological characteristics and yield of safflower (Carthamus tinctorius L.) under different irrigation regimes. These irrigation regimes include complete irrigation (S0), irrigation cut-off at stem elongation (S1), flowering and pollination (S2), and grain filling (S3) stages. The S1 irrigation level led to a decrease in Fv/Fm (5 %), relative water content (RWC) of the leaf (17 %), leaf total chlorophyll (22 %), and soluble proteins of the leaf (21 %) an increase in electrolyte leakage (33 %), carotenoids (43 %), proline content (42 %) and soluble sugars of the leaf (39 %) compared with S0 irrigation level. The safflower leaf showed increased Fv/Fm, RWC, total chlorophyll, and soluble proteins when organic fertilizer was used alone or in combination with chemical fertilizers under irrigation cut-off conditions. Additionally, the use of organic fertilizer resulted in a decrease in carotenoid content, proline content, and soluble sugars of the safflower leaf. The highest biological yield was obtained with S0 irrigation level (21.62 t ha−1) and N3 integrated nutrition system (21.93 t ha−1), respectively. The N3 and N2 nutrition systems increased the grain yield by 3.34 t ha−1 and 3.56 t ha−1 in 2015 and 2016, respectively. The greatest negative effect on biological yield was observed when irrigation was cut-off during the vegetative stage, while the most detrimental impact on grain yield occurred when irrigation was ceased during the flowering and pollination stages. Overall, the results indicated that N2 and N3 nutrition systems while implementing irrigation cut-off at various growth stages reduced the negative impact of water deficiency on plants. This leads to decreased production costs for stress-resistant osmolytes and, consequently, improved grain yield and biological yield.

The study of propagation characteristics of the millimeter-wave vortex in magnetized plasma by using the FDTD method

It is pointed out that the millimeter-wave vortex may contribute to an efficient method of plasma heating since it was found that the millimeter-wave vortex can propagate in magnetized plasma even in which the normal plane wave is in cut-off condition. Then, it was assumed that the vortex field was the Laguerre–Gaussian (L–G) mode which is a free-space solution, but the generation and stable propagation of the L–G mode vortex are not easy in the millimeter frequency range. On the other hand, it is known that the millimeter-wave hybrid mode of the cylindrical corrugated waveguide also has vortex properties. In this paper, we investigate the propagation characteristics of a millimeter-wave vortex of a hybrid mode of a cylindrical corrugated waveguide in the magnetized plasma by using three-dimensional numerical simulations with the finite-difference time-domain (FDTD) method. It is found that the millimeter-wave vortex of hybrid mode also can propagate in the magnetized plasma even in a condition in which the normal plane wave is in cut-off condition, and the propagation power in the plasma is highly dependent on the topological charge l.

Influences on Reliable Capacity Measurements of Hard Carbon in Highly Loaded Electrodes

Lithium-ion batteries (LIBs) are the current state of the art energy storage technology. However, to tackle the steady increasing demand for clean but also sustainable energy, other complementary cell chemistries are gaining significant importance. Sodium-ion batteries (NIBs) are considered to be a drop-in technology that can benefit from the knowledge about processing of LIBs and its existing manufacturing structures.For the development of a sodium-ion full-cell, commercially available hard carbon (HC) as an anode material was characterized within a half-cell setup. On the one hand, those measurements are essential to characterize individual electrodes in order to obtain electrochemical information that is needed to set up the full cell, e.g. balancing. On the other hand, the exact determination of the HC capacity is prone to errors, mainly due to the cut-off potential being close to 0 V against metallic sodium. This behavior and also electrolyte degradation in presence of elemental sodium were studied.It has been found that the potential of the current carrying sodium counter electrode in half-cells is not stable, resulting in measurement inaccuracies, particularly at elevated C-rates when charging is controlled by a cut-off potential. On the contrary, by using a three-electrode setup, the current-free reference electrode provides stable cut-off conditions. An improved setup for half-cell measurements is suggested to obtain reliable and reproducible capacity readings for HC anodes with an areal capacity of up to 2.4 mAh/cm². Figure : Schematic overview about the investigated control voltages and their effect on the electrochemical performance. [1] The initial coulombic efficiency (ICE) of HC is a current challenge because it is relatively low at about 80% and it can vary for different HC materials. Therefore, precise measurements are a necessity to develop HC materials with higher ICEs.Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – EXC 2154.[1] Müller, C., Wang, Z., Hofmann, A., Stüble, P., Liu-Théato, X., Klemens, J., Smith, A., “Influences on Reliable Capacity Measurements of Hard Carbon in Highly Loaded Electrodes” Batteries & Supercaps 2023, e202300322. Figure 1

Diffusion-Equation-Based Electrical Modeling for High-Power Lithium Titanium Oxide Batteries

Lithium titanium oxide (LTO) batteries offer superior performance compared to graphite-based anodes in terms of rapid charge/discharge capability and chemical stability, making them promising candidates for fast-charging and power-assist vehicle applications. However, commonly used battery models often struggle to accurately describe the current–voltage characteristics of LTO batteries, particularly before the charge/discharge cutoff conditions. In this work, a novel electrical model based on the solid-phase diffusion equation is proposed to capture the unique electrochemical phenomena arising from the diffusion mismatch between the positive and negative electrodes in high-power LTO batteries. The robustness of the proposed model is evaluated under various loading conditions, including constant current and dynamic current tests, and the results are compared against experimental data. The experimental results for LTO batteries exhibit remarkable alignment with the model estimation, demonstrating a maximum voltage error below 3%.

Is Thomas Tuchel wrong? Evaluation of hexagonal shaped drills based on machine learning and position data

As a variation of small-sided games (SSGs), Thomas Tuchel's hexagonal shaped possession drills attracted a lot of attention in coaches’ soccer education. Changing certain variables (e.g. pitch size) is one traditional approach to provide an optimal stimulus for a specific training goal. Therefore, the presented field study investigated whether hexagonal shaped drills show changes in tactical key performance indicators (KPIs) using positional data in a controlled experimental setting. Data were collected using player tracking systems (1 Hz) in 5 versus 5 SSGs in both the full-size pitch and pitch with cut-off corners condition. At match-related level, trial duration and outcome were examined. At player-related level, the tactical KPIs effective playing space (EPS), length-per-width ratio, space control and overplayed defenders were analyzed. The results show significant differences in length-per-width ratio (attacking team), the EPS and space control (30m-zone). However, it could not be confirmed that hexagonal shaped drills are played more vertically and faster toward the goal than on a normal pitch, as there were no changes in trial duration, outcome or overplayed defenders. Nevertheless, an experimental positional data analysis paradigm is a useful approach to investigate tactical principles in high-level professional soccer.

A bimetal strategy for suppressing oxygen release of 4.6V high-voltage single-crystal high-nickel cathode

High-voltage cathode materials, such as single-crystal high-nickel layered oxide materials, are a necessary condition for achieving high energy density lithium-ion batteries, but they have to be accompanied by the structural instability and irreversible release of lattice oxygen during operation, posing serious safety hazards. Here, to solve the lattice oxygen release issue of single-crystal high-nickel cathode, we propose an improved strategy for overall cathode by synchronously addressing interface and lattice instability, ensuring stable operation at a high voltage up to 4.6 V. By Al-doping, in the bulk phase, we intensify the charge transfer between transition metals and oxygen, and the columnar effect caused by doped atoms effectively alleviates internal strain, thereby significantly limiting lattice shrinkage and then suppressing oxygen release. On the other hand, the protective layer of LiNbO3 as the fast ion conductor formed at the cathode interface suppresses parasitic reactions and hinders lattice oxygen loss caused by dissolution of transition metals. Therefore, after 200 cycles at a cut-off voltage of 4.6 V, our cathode material still maintains a capacity retention rate of 89.1%. Density functional theory (DFT) calculations predict the effective suppression of oxygen release for the modified cathode materials, which has been further confirmed by differential electrochemical mass spectrometry (DEMS) tests. This work provides a new perspective for solving the problem of oxygen release under high cut-off voltage conditions for single crystal high nickel cathode.

The Hull Cutoff condition for magnetic insulation in crossed-field electron devices in the presence of a slow-wave structure

Crossed-Field Vacuum Electron Devices are ubiquitous in the High-Power Microwave field in either an oscillator/source or amplifier variant. A typical configuration consists of a magnetically insulated laminar electron flow in an anode–cathode gap with crossed electric (∝V, voltage) and magnetic (B-) fields and a series of open resonant cavities/vanes located on the anode block that serve as a slow-wave structure (SWS). The SWS slows the phase velocity of the electromagnetic signal down so that the wave becomes synchronous with a layer of the electron flow but is often neglected when calculating the Hull magnetic field necessary to insulate the electrons. In particular, the guiding design equation for the critical cutoff B-field assumes a smooth anode wall. In this paper, we show that such an assumption severely narrows the operating regime in B–V space and that upon inclusion of a revised Hull Cutoff condition taking into account the SWS, operation at lower B and higher V is possible. This revised Hull Cutoff criterion for magnetic insulation in crossed-field devices is corroborated by Particle-in-Cell simulations using CST Particle Studio.

Application of linear regression method to predict microcontroller-based infusion fluid volume using IoT

Infusion is a medical device under certain conditions used to replay lost fluids and balance the body's electrolytes. In emergency condition for examples in patients with dehydration, severe metabolic stress that causes hypovolemic shock, acidosis, dengue hemorrhagic fever (DHF), burn hemorhagle shock and trauma,infusion are needed immediately to replace lost body fluids. The manufacture of this system use two LM393 Optocoupler Infrared Sensors. Infrared sensors detect deteeted objects, namely droplets. If no droples are detected, the infrared sensor will not work or is a cut-off condition. This system is the Internet of Things (IoT). With the platform used, Ubidots, so that monitoring can be done with a smartphone. A warning will be send the infusion level has reached 100ml, so Ubidots will automatically send a notification in the form of an E-mail.

Mitigating Chemo-Mechanical Degradation in Sulfide-Based All-Solid-State Batteries Comprising Sulfur Composite Cathode and Li–Si Alloy Anode

In this study, all-solid-state batteries consisting of an Li2S5–P2S5 (LPS) glass electrolyte, a sulfur/LPS glass/carbon composite cathode, and an Li–Si anode are prepared and tested under high cut-off voltage conditions (0.5–3.7 V) to elucidate the effect of LPS redox activity on the chemo-mechanical stability of LPS-based cells. The cell cycled in the voltage range 0.5–3.7 V exhibits unstable charging behaviors and voltage noise, with substantial LPS oxidative decomposition. X-ray photoelectron spectroscopy and impedance spectra analyses of a three-electrode system reveal that the cathode resistance is remarkably increased by the oxidative decomposition of LPS when the cell is charged to 3.7 V, which induces dendritic lithium growth at the anode side, resulting in a micro-short circuit through the electrolyte. Composite anodes of Li3PS4 glass+Li–Si alloy (Type 1) and Li3N+LiF+Li–Si alloy (Type 2) are also prepared for all-solid-state batteries (ASSBs) with LPS glass electrolyte and sulfur/LPS glass/carbon composite cathode. Using a three-electrode system, the anode and cathode potentials are separated, and their polarization resistances are individually traced. Even under high-cutoff-voltage conditions (3.7 V), Type 1 and 2 cells are stably cycled without voltage noise for >200 cycles. Although cathode polarization resistance drastically increases after 3.7 V charge owing to LPS oxidation, LPS redox behavior is fairly reversible upon discharge–charge unlike the non-composite alloy anode cell. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis reveals that the enhanced cyclability is attributed to uniform Li–Si alloying throughout the composite anode, providing more pathways for lithium ions even when these ions are over-supplied via LPS oxidation. These results imply that LPS-based cells can be reversibly cycled with LPS redox even under high-cutoff voltages, as long as non-uniform alloying (lithium dendrite growth) is prevented.

Research on serial lithium‐ion battery alternating discharge equalization control systems

AbstractTo improve the discharge equalization efficiency of the battery and prevent the occurrence of overdischarge, in this paper, the 18,650 ternary lithium battery is taken as the object of investigation, and an alternating equalization control system for the discharge process of serial cells is proposed. The system implements the alternating discharge of serial cells by switching on and off, using state of charge (SOC) as the equalization variable, and eventually completes the equalization control of the entire battery pack. Discharge simulations were performed in Matlab/Simulink for faulty and normal operating conditions of the battery pack, respectively. The findings indicate that even in the presence of a malfunction, the battery pack can continue to operate continuously for a while; in contrast, under ideal circumstances, the battery pack is capable of maintaining SOC balance throughout the discharge process. Eventually, five batteries are used to construct the experimental platform for the alternating equalization system. The battery pack can still perform selective discharge under fault conditions until the battery pack reaches the discharge cutoff condition. Under normal conditions, the maximum SOC difference of all five batteries can stabilize at about 1%. The experimental results show that the proposed equalization control system can achieve the equalization of battery discharge and prolong the discharge time, and can prevent the occurrence of battery over discharge.

Supply chain contracting with asymmetric cost information and behavioral preferences: Theory and experiment

We investigate a supply chain composed of a retailer who designs a contract with wholesale price and order quantity, and a supplier who has private information of low or high unit production cost. The standard benchmark predicts that in equilibrium, the optimal contract possesses a threshold dividing a cutoff condition and a non-cutoff condition for the retailer. Under the cutoff condition, retailers trade only with low-cost suppliers, while under the non-cutoff condition, retailers trade with both low-cost and high-cost suppliers. Suppliers accept the critical non-negative profit contracts. We incorporate behavioral factors of the retailer’s risk preference and the supplier’s fairness concern in view of the decision-making scenario. The behavioral model shows that the risk preference influences the threshold of the optimal contract design, while the fairness concern only affects the optimal wholesale price. We conduct a laboratory experiment to examine both parties’ decision behaviors and find that human retailers with risk-averse preference make local optimal strategies rather than global optimal strategies, which counter-intuitively improves the channel profit; and human suppliers with fairness concern enables human retailers to provide fair contracts, which increases the channel profit and balances the channel profit distribution. These findings imply that the behavior of retailers and suppliers plays an important role in mechanism design of supply chains.

Stability assessment of a non-circular tunnel face with tensile strength cut-off subject to seepage flows: A comparison analysis

This work aims to develop a numerical-analytical framework within the kinematic approach of limit analysis to assess the stability of non-circular tunnel faces under seepage conditions with tensile strength cut-off from a discretization-based perspective. Considering the overestimation of the tensile strength of the soil by the Mohr-Coulomb criterion, a modification based on the concept of tensile strength cut-off is recommended to reduce or eliminate the tensile strength. A modified 3D rotational discretization-based failure mechanism incorporating the tension cut-off is generated point-to-point starting from a real non-circular tunnel face to model the face failure, where the failure surface on the top intersects more rapidly due to the increasing rupture angle in the tensile regime. The seepage towards the non-circular tunnel face is numerically simulated, and then the numerical seepage field is extracted into the 3D discretization-based failure mechanism. Within the kinematic approach, the seepage effect is introduced from two aspects: pore pressure and seepage force. A hybrid optimization routine is employed to search for the maximum required face pressure. The developed framework is validated by comparisons with numerical fluid-mechanical simulations and previous studies. Afterward, parametric analyses are carried out on different seepage conditions, different face pressure distributions, different soil strengths, and different tension cut-off conditions. The developed framework can give insight into the combined effect of the tension cut-off and seepage on the stability of non-circular tunnel faces under various conditions.

Negative curvature fiber for suppressing high-order radial OAM modes transmission

The combination of terahertz (THz) wave and the orbital angular momentum (OAM) multiplexing technology can further improve the communication capacity. Compared to other outer cladding structures, the negative curvature structure has been proven to provide stronger confinement effect on electromagnetic waves. Here, we propose a novel polymer (COC TOPAS) fiber which consists a central hollow-core, annular region and single layer negative curvature circle tubes as outer cladding for terahertz OAM modes transmission. The mode map is established by mathematical analysis of cut-off conditions for the vector modes, and the excitation of high-order radial modes in the fiber is successfully suppressed. In addition, the effective refractive index, confinement loss, effective mode area, mode purity and dispersion characteristics of the fiber are investigated under the condition of ‘single mode’ operation in the frequency range of 2.0–3.0 THz.

Risk Factors for Cefoperazone/Sulbactam-Induced Coagulation Disorder.

Cefoperazone/sulbactam is a β-lactam/β-lactamase inhibitor combination effective against intra-abdominal, urinary tract, and respiratory infections. Although some studies have suggested that cefoperazone/sulbactam is associated with coagulation disorders, it remains debatable whether the combination of cefoperazone/sulbactam with tigecycline or valproic acid increases the risk of bleeding, as both drugs can lead to coagulation disorders. This study aimed to explore the risk factors of cefoperazone/sulbactam-induced coagulopathy. This was a single-center, retrospective, nested case-control study. The sample groups were derived from individuals registered at the Department of Neurosurgery, Shanxi Provincial People's Hospital. Propensity score matching (PSM) was used to adjust for demographic data. Conditional logistic regression was used to estimate the matched odds ratios representing the odds of cefoperazone/sulbactam-induced coagulopathy (CIC), and a receiver operating characteristic curve was used to determine the optimal cut-off conditions. After PSM, 155 and 56 patients were included in the control and case groups, respectively. Multivariate analysis revealed that advanced age, treatment duration, and total dose were independent risk factors of cefoperazone/sulbactam-induced coagulation disorders. Concomitant use of vitamin K was an independent protective factor against CIC. The optimal cut-off for the length of treatment was 5 d, and the cut-off for the total dose was 48 g. Tigecycline and valproic acid were not associated with CIC. Advanced age and long treatment duration are risk factors for CIC. Supplementation with vitamin K during cefoperazone/sulbactam treatment was associated with a reduced risk.

A Gradient Vector Descent Strategy for Localizing Acoustic Emission Sources in Discontinuous Structures With a Hole

The analysis of acoustic signals to localize acoustic sources (AE) has emerged as a kind of favored approach. Despite recent advances, the task of localizing acoustic emission sources such as impacts in the discontinuous structure with a hole still poses a considerable challenge. A localizing method based on the gradient vector descent method is presented in this paper, which is applied to a discontinuous structure with a hole. When an impact event is observed, this method will first calculate the time difference-of-arrival values of different sensors and set the most likely location of impact as origin coordinates. Then the tracks of acoustic signals on the surface of the structure are calculated by vector analysis, which is used to compute the difference of path for different sensors. The calculated parameters will be used in an objective function, then coordinates of impact will be corrected by the gradient vector descent strategy and difference-of-path values will be recalculated to complete iteration until satisfying the cut-off condition. In addition, simulation and Laser Doppler experiments verify the correctness of the propagation path. The experiment results of extensive Pencil lead break (PLB) tests on the structure with a hole further indicate that the proposed method can achieve higher localizing accuracy (the average error is 1.034cm) than traditional methods with a relatively low computational cost.

Electron trajectories in a collisional crossed-field gap

The Hull cutoff represents the maximum magnetic field in a vacuum crossed-field gap (CFG) such that an electron emitted from the cathode reaches the anode. Prior studies demonstrated that introducing ions into a CFG always causes increased excursion of electrons toward the anode. In this paper, we assess a collisional CFG by incorporating collision frequency into the electron force law. The theoretical electron trajectories agree well with a one-dimensional particle-in-cell simulation and demonstrate that emitted electrons always cross a collisional CFG. We derive a modified Hull cutoff condition for a collisional CFG corresponding to an electron reaching the anode with zero velocity in the direction of the electric field. Rather than representing the threshold for magnetic insulation, this condition gives the maximum magnetic field and maximum collision frequency for which an electron reaches the anode without turning around; higher magnetic fields and/or collision frequencies cause the electron to turn around before crossing the gap. Further increasing either quantity causes the electron to change direction more frequently as it crosses the gap, noticeably increasing the transit time with each change in electron direction. In the limit of high collision frequency, the electron velocity across the gap approaches a constant, meaning that electrons will reach the anode at nonzero velocity. The transit time above this condition increases smoothly and monotonically with increasing magnetic field or collision frequency. These results elucidate the implications of collisions on magnetic insulation for future assessments of the limiting current in a collisional CFG.