Search Results (270)

The rapid advancement of high-performance electronics has intensified the demand for wide-bandgap semiconductor materials capable of operating under high-power and high-temperature conditions. Among these, silicon carbide (SiC) has emerged as a leading candidate due to its superior thermal conductivity, chemical stability, and mechanical strength. However, the high cost and complexity of SiC wafer fabrication, particularly in slicing and exfoliation, remain significant barriers to its widespread adoption. Conventional methods such as wire sawing suffer from considerable kerf loss, surface damage, and residual stress, reducing material yield and compromising wafer quality. Additionally, techniques like smart-cut ion implantation, though capable of enabling thin-layer transfer, are limited by long thermal annealing durations and implantation-induced defects. To overcome these limitations, ultrafast laser-based processing methods, including laser slicing and stealth dicing (SD), have gained prominence as non-contact, high-precision alternatives for SiC wafer exfoliation. This review presents the current state of the art and recent advances in laser-based precision SiC wafer exfoliation processes. Laser slicing involves focusing femtosecond or picosecond pulses at a controlled depth parallel to the beam path, creating internal damage layers that facilitate kerf-free wafer separation. In contrast, stealth dicing employs laser-induced damage tracks perpendicular to the laser propagation direction for chip separation. These techniques significantly reduce material waste and enable precise control over wafer thickness. The review also reports that recent studies have further elucidated the mechanisms of laser–SiC interaction, revealing that femtosecond pulses offer high machining accuracy due to localized energy deposition, while picosecond lasers provide greater processing efficiency through multipoint refocusing but at the cost of increased amorphous defect formation. The review identifies multiphoton ionization, internal phase explosion, and thermal diffusion key phenomena that play critical roles in microcrack formation and structural modification during precision SiC wafer laser processing. Typical ultrafast-laser operating ranges include pulse durations from 120–450 fs (and up to 10 ps), pulse energies spanning 5–50 µJ, focal depths of 100–350 µm below the surface, scan speeds ranging from 0.05–10 mm/s, and track pitches commonly between 5–20 µm. In addition, the review provides quantitative anchors including representative wafer thicknesses (250–350 µm), typical laser-induced crack or modified-layer depths (10–40 µm and extending up to 400–488 µm for deep subsurface focusing), and slicing efficiencies derived from multi-layer scanning. The review concludes that these advancements, combined with ongoing progress in ultrafast laser technology, represent research opportunities and challenges in transformative shifts in SiC wafer fabrication, offering pathways to high-throughput, low-damage, and cost-effective production. This review highlights the comparative advantages of laser-based methods, identifies the research gaps, and outlines the challenges and opportunities for future research in laser processing for semiconductor applications. Full article

This study investigates the effectiveness and underlying mechanisms of electropulsing treatment (EPT) for rapid stress relief of Ti-6Al-4V titanium alloy. Stress relief is an essential step in manufacturing processes to ensure long component lifespan. Residual stress accumulation within a component is often undesirable, as it may lead to premature failures. Currently, the stress relief of titanium alloys is typically carried out using an annealing heat-treatment process in a vacuum furnace. However, this method is time-consuming, usually requiring several hours. In this paper, an alternative fast stress relief method by EPT was investigated. A controllable pulsing treatment using alternating high density pulsing current with short pulse width was carried out. Results showed that EPT is effective in relieving residual stress in Ti-6Al-4V alloy. Up to 90% of the surface residual stresses induced by shot peening were successfully relieved by EPT with a treatment duration of only 114 ms. Reductions of low-angle grain boundaries (2–10°), local misorientation, and deformed grains were observed, while no significant grain growth or phase transformation was found. The stress-relief mechanism of EPT is attributed to the combined effects of dislocation movement driven by electron wind force (EWF), dislocation creep at elevated temperatures, and dislocation glide due to local yielding of residual stress under high-temperature conditions. The temperature rise during EPT was identified as a significant factor enabling stress relaxation. Full article

In the last 32 years (1993–2024), the application of electric fields in soil management (soil electrokinetic, SEK) has undergone several stages of optimization and intensification. SEK has used both alternating current (AC) and direct current (DC). Numerous fields, including agriculture, sedimentation, phosphorus management in soil and sludge, fertilizer production, consolidation, reclaiming salt-affected soils, metal extraction, dewatering, remediation of contaminated soil (both organic, such as PFAS, and inorganic, such as heavy metals), and soil nutrient availability, have utilized the SEK concept. Numerous innovations were included in the SEK equipment’s design or combined with other biological, chemical, and physical processes. While we recently published a review article on soil electrokinetic/electroosmosis–vacuum systems for sustainable soil improvement and contaminant separation, the current study illustrates the role of applying the pressure-assisted soil electrokinetics technique and shows the effect of the opposite technique. Four points were used to show the function of pressure-assisted soil electrokinetics based on our analysis of six search engines from 1993 to 2024 (the previous 32 years), including (1) polluted soil remediation, (2) dewatering, (3) soil improvement, and (4) making soil ready for electrokinetic action by applying pressure. In contrast to other intensification methods (such as reverse polarity, pulsed electric field, and design change), we found very few publications addressing pressure-assisted soil electrokinetics throughout the literature search. Most investigations focused on the dewatering mechanism, despite the paucity of relevant papers. In contrast to conventional electrokinetic remediation, pump-assisted electrokinetic-flushing remediation increased the removal efficiencies of Cs⁺ and Co²⁺ from contaminated soil by 2% and 6%, respectively. Additionally, the results demonstrated that the pressured electro-osmotic dewatering approach outperformed the conventional electrokinetic techniques. At 40 kPa, hydraulic conductivity was reduced four-fold by electro-rehabilitation for alternative fuels, while at 100 kPa, it was reduced three-fold. It was also observed that pressure may be used to achieve the soil ready for electrokinetic action in order to guarantee proper operation. Since there are not many articles on the subject, future research may examine how pressure-assisted soil electrokinetics can be integrated with vacuum systems, reverse polarity mode, pulsed electric field mode, modifying the SEK design, overcoming the formation of cracks, etc. Full article

Sodium-ion batteries (SIBs) are gaining attention in research and industry as a sustainable alternative to lithium-ion batteries (LIBs). However, the advantages of sodium over lithium in terms of accessibility, price, and environmental impact are currently not fully exploited because of inexperience in production, leading to inhomogeneities in their behavior. Using electrical (e.g., open-circuit voltage curve (OCV), electrochemical impedance spectroscopy) and non-electrical measurement methods (e.g., laser scanning microscopy, computed tomography), three widely used LIB technologies and one SIB technology, all with the same rated capacity (1500 mAh) and format (18650), are compared in this article. The study reveals significant differences, such as a 12% lower cell weight at the same rated capacity of the SIB using less windings in the jelly roll, as well as a high energy density cell configuration and a much more severe dependency of the discharge capacity on temperature, exceeding the LIBs by at least a factor of 5. Additionally, the impedance of the SIB differs due to slower ion kinetics on the electrodes, showing relevant differences in both the frequency behavior and the pulse relaxation to the LIBs. An OCV reconstruction indicates the sparsity in the available literature data and the necessity to further investigate the characteristics of the SIB to validate it as a drop-in technology on the market. Full article

We present a time-domain direct current (DC) approach to differentiate positive- (PE) and negative-electrode (NE) contributions from two-electrode full-cell signals in lithium-ion batteries, enabling electrode-resolved diagnostics without specialized instrumentation. The responses of a LiNi_0.8Co_0.1Mn_0.1O₂ (PE)/graphite (NE) cell were recorded across −20 to 20 °C during galvanostatic pulses and subsequent open-circuit relaxations, alongside electrochemical impedance spectroscopy (EIS) measurements. These responses were analyzed using an equivalent-circuit-based model to decompose them into terms with characteristic times. Their distinct temperature dependences enabled attribution of the dominant terms to PE or NE, especially at low temperatures where temporal separation is substantial. The electrode attribution and activation energies were cross-validated against three-electrode measurements and were consistent with EIS-derived time constants. Reconstructing full-cell voltage transients from the identified terms reproduced the measured electrode-specific behavior, and quantitative comparisons showed that the DC time-domain separation aligned closely with directly measured PE/NE overpotentials during the current pulse. These results demonstrate a practical pathway to extract electrode-resolved information from cell voltage alone, offering new methodological possibilities for battery diagnostics and management while complementing three-electrode and alternating current (AC) techniques that are often constrained in field applications. Full article

Conventional electro-permanent magnet (EPM) lifting/holding systems, typically based on NdFeB magnets, face efficiency limitations because continuous current is required either for standby condition to avoid accidentally attracting the objects around or for gently approaching and separating from sensitive iron-based target objects during gripping and releasing processes. Low Coercive Force (LCF) magnets offer an alternative, as their magnetization can be tuned with short current pulses and maintained without continuous current. However, this approach demands fast and precise flux control to eliminate the issues mentioned above. This paper introduces a novel flux control method based on the Hill Climb Search (HCS) algorithm. Once the required flux is identified, the system rapidly adjusts the magnetization of LCF magnet by applying optimized pulse trains within a short time. Experimental evaluation confirms that the proposed method effectively establishes and sustains the target magnetization level without additional current input. This approach has significant potential to advance and expand the use of Low Coercivity EPM systems as an alternative to classical systems. Full article

Background: Hidradenitis suppurativa (HS) is a chronic, recurrent skin disease that significantly impairs patients’ quality of life both physically and mentally. It often requires a complex treatment process. Laser therapy, which is highly effective and well-tolerated, is an effective alternative to pharmacological treatment. This review aimed to synthesize information on laser therapy for HS, highlighting its clinical outcomes. In the current management guidelines for hidradenitis suppurativa, laser therapy is listed as one of the recommended procedural treatment options, applicable at different stages of disease severity (Hurley I–III). Methodology: This systematic review was conducted using the PubMed and Embase databases, regardless of publication year, in accordance with the PRISMA guidelines. Applied key search terms were: “laser AND (hidradenitis suppurativa OR acne inversa)”. A total of 26 relevant studies were identified, and their data were extracted. Results: The CO₂ laser is mainly used in advanced stages of the disease (Hurley II–III). It allows effective removal of lesions with a minimal risk of relapse and a good aesthetic effect. The Nd:YAG (neodymium-doped yttrium aluminum garnet; Nd: Y₃Al₅O₁₂) laser is effective at various stages of the disease (Hurley I–III) by reducing inflammation and destroying hair follicles, thereby reducing disease symptoms. IPL (intense-pulse light) therapy, or the combination of IPL with radiofrequency (RF), known as LAight^®, delivers significant clinical improvement and enhanced quality of life, especially in less advanced cases. The diode laser works precisely and deeply, leading to the selective destruction of hair follicles and fistulas. The Alexandrite laser (755 nm) also limits hair follicle occlusion and is particularly effective in patients with lighter skin phototypes. Conclusions: In modern dermatology, laser therapy is a reliable treatment for HS, contributing to effective regression of the disease at all stages. Combination strategies seem to improve clinical outcomes and enable a more personalized approach to HS, which is essential as various factors influence therapeutic efficacy. Further, larger-scale studies are needed to validate long-term outcomes and establish clinical guidelines. Full article

Pulse wave velocity (PWV) is a useful biomarker in the monitoring and risk stratification of various cardiovascular diseases including hypertension. The current gold standard for non-invasive measurement is carotid-femoral PWV (cfPWV) measurement via direct tonometry. However, cfPWV provides only a global PWV measure, which emphasises the need for an alternative capable of local PWV assessment. There are several alternatives for local PWV measurement proposed in the literature and one promising alternative is ultrasound, which offers good penetration depth, accessibility, and a relatively low cost, making it well-suited for non-invasive, real-time acquisition of haemodynamic parameters for PWV estimation. This paper aims to evaluate the different approaches for ultrasound-based acquisition while considering technical and physiological constraints to optimise the accuracy, reliability, and reproducibility of the parameters collected for estimation. In particular, this paper focuses on the flow-area (QA) and lnDiameter-velocity (lnDU) methods, which require local area and velocity data for PWV estimation. Accordingly, this paper discusses the use of ultrasound imaging in vessel data acquisition, highlights various challenges and considerations to be managed during acquisition and processing, outlines the different ultrasound-based imaging modalities for acquiring area and velocity data, and compares the simultaneous and non-simultaneous acquisition of data for PWV estimation. Full article

Due to the ever-increasing energy demand, Algeria’s sustainable energy crisis is a significant problem. Plant and crop residues can be a solution to this problem if they are used for bioethanol production, a viable alternative to fossil fuels. This study explores the potential of existing agricultural crop residues to overcome the sustainable energy crisis in Algeria. Agricultural residues such as cereals, roots and tubers, pulses, oil crops, vegetables, and fruits have great potential to solve the problem. The agricultural residues that are normally wasted can be utilized to produce bioethanol, which provides sustainable energy and also help to obtain a clean environment. It has been found that 1.65 million tons of bioethanol can be produced from Algeria’s available residues, which is equivalent to 44.10 petajoule of energy. Cereal and fruit residues contribute to most bioethanol generation, about 47.22% and 23.38%, respectively. In addition, bioethanol generated from residue can be used in Algeria’s transportation sector. Considering Algeria’s current energy condition, gasoline blended with ethanol such as E10 and E5 can be used in Algerian vehicles since no modification of vehicles is needed for utilizing these fuels. Research indicates that lignocellulosic biomass sources in Algeria, such as Alfa, olive pomace, and cereal straw, could provide up to 0.67 million tons of oil equivalent (Mtoe), representing approximately 4.37% of the energy consumption of the transport sector in Algeria. Algeria has the potential to produce up to 73.5 Mtoe and 57.9 Mtoe of renewable energy utilizing the energy crops. This study will also encourage relevant policymakers to develop sustainable energy policies that will enhance the renewable energy share in Algerian energy dynamics. Full article

This systematic review examines the combined use of electroencephalography (EEG) and transcranial electrical stimulation (tES) in both clinical and healthy populations. The review focuses on EEG’s role in guiding, monitoring, and evaluating tES interventions and assesses the generalizability of EEG responses to different tES protocols. A comprehensive search across Google Scholar, PubMed, Scopus, IEEE Xplore, ScienceDirect, and Web of Science identified 162 relevant studies using the query: “EEG AND (tDCS OR transcranial direct current stimulation OR tACS OR transcranial alternating current stimulation OR tRNS OR transcranial random noise stimulation OR tPCS OR transcranial pulsed current stimulation)”. Quality was assessed using the Quality Assessment Tool for Quantitative Studies (QATQS). Most studies used EEG post tES to assess neuromodulatory effects, with fewer studies using EEG for protocol design or incorporating real-time EEG for adaptive stimulation. Some studies integrated EEG both before and after stimulation, but considerable heterogeneity in tES parameters and EEG metrics limited reproducibility and comparability. Many studies reported non-significant EEG changes despite standardized approaches. Methodological quality was generally low, and the link between EEG changes and clinical outcomes remains unclear. The findings underscore the potential of EEG-informed, personalized tES protocols, though the use of real-time closed-loop systems remains a limited approach in current research. Full article

Natural food colourants are gaining momentum in the food industry due to their clean-label appeal, safety, and potential health benefits. However, their practical application is often constrained by instability under environmental stressors such as pH fluctuations, heat, light, and oxygen. In response, both traditional and innovative strategies have emerged to improve pigment stability, with some studies reporting up to 50–80% retention of colour intensity under optimised conditions. Most existing research focuses on extraction, with limited emphasis on post-processing stability. This article reviews a wide range of food processing strategies aimed at enhancing the stability of natural pigments. It covers conventional and emerging approaches, including natural chemical stabilisers such as co-pigments, antioxidants, and metal ion chelators, physicochemical methods such as micro- and nanoencapsulation using biopolymers, and physical interventions involving drying technologies, particle size modification, and protective packaging. Modern technologies such as high-pressure processing, pulsed electric fields, ultrasound, and cold plasma are discussed as promising non-thermal alternatives, demonstrating 20–70% improvement in pigment retention compared to untreated controls. By integrating these diverse approaches, this article highlights current advancements, identifies knowledge gaps, and discusses future directions to support the development of stable, sustainable, and functional natural colourant systems for next-generation food products. Collectively, these approaches demonstrate significant potential to improve the performance and resilience of natural pigments in complex food systems. Full article

This paper introduces a novel sensorless speed control strategy for squirrel-cage induction motors, which ensures robust operation in the presence of external disturbances by applying the state feedback technique. Based on the induction motor model, the speed controller is synthesized by defining a sliding variable that is driven to zero through the supertwisting control law, ensuring the stabilization of the tracking error. The time derivative of the error variable is estimated using a robust differentiator based on the sliding-mode twisting algorithm, thereby eliminating the need to estimate the load torque. A robust observer is employed to estimate the rotor speed and flux linkages simultaneously. The convergence of the estimated rotor flux linkages is enforced through a discontinuous first-order sliding-mode input, while the convergence of the rotor speed estimate is attained via a quasi-continuous super-twisting sliding-mode input. In the proposed model, the inductance parameters are determined from the magnetizing inductance and the leakage inductances of the stator and rotor. A procedure is also presented for adjusting the stator resistance and leakage inductances, taking into account the squirrel-cage rotor type and the skin effect in alternating current conduction. The performance of the sensorless speed control system under variations in load torque and reference speed is validated through experimental testing. The rotor speed estimation provided by the robust observer is accurate. The reference speed tracking control, evaluated using a 1600–1700 rpm pulse train phase-shifted by 4 s with respect to a 0–0.5 N·m pulse train, demonstrates high precision. Full article

Research on the WEDM process has traditionally focused on analyzing discharge initiation, material removal mechanisms and surface formation from the perspective of the machined part. However, the same phenomena also affect the tool, namely the wire electrode. A comprehensive understanding of the process requires to examine how these effects impact the electrode itself, particularly in terms of wear. Despite its significance, electrode wear in WEDM is not a topic frequently addressed in the literature. The most common method for evaluating wear involves determining the wire wear ratio (WWR), based on the electrode’s weight before and after machining. However, this approach does not provide insight into changes in the microstructure of the electrode surface. This study presents an alternative approach to interpreting wire electrode wear, using surface roughness parameters in relation to the surface texture of the machined workpiece. Measurements were conducted using an optical focus variation microscope. The influence of selected process parameters—including discharge current I_p, pulse-off time t_off and workpiece height h—on selected surface roughness parameters was investigated. The experimental tests were carried out for three alloys representing distinct material groups: 42CrMo4 steel, Inconel 718 nickel alloy, and Ti6Al4V titanium alloy. The results were compared with the roughness parameters of the corresponding machined surfaces. The presented interpretation of the key factors affecting the electrode surface condition after WEDM serves as an initial step in a broader research initiative. It lays the foundation for further studies on wire electrode wear and the development of new wear assessment parameters such as the electrode wear index based on surface texture parameters. Full article

The transition to high-energy-density lithium metal batteries (LMBs) is essential for advancing electric vehicle (EV) technologies beyond the limitations of conventional lithium-ion batteries. A key challenge in scaling LMB production is the precise, contamination-free separation of lithium metal (LiM) anodes, hindered by lithium’s strong adhesion to mechanical cutting tools. This study investigates high-speed, contactless laser cutting as a scalable alternative for shaping double-coated LiM anodes. The effects of pulse duration, pulse energy, repetition frequency, and scanning speed were systematically evaluated using a nanosecond pulsed laser system on 30 µm LiM foils laminated on both sides of an 8 µm copper current collector. A maximum single-pass cutting speed of 3.0 m/s was achieved at a line energy of 0.06667 J/mm, with successful kerf formation requiring both a minimum pulse energy (>0.4 mJ) and peak power (>2.4 kW). Cut edge analysis showed that shorter pulse durations (72 ns) significantly reduced kerf width, the heat-affected zone (HAZ), and bulge height, indicating a shift to vapor-dominated ablation, though with increased spatter due to recoil pressure. Optimal edge quality was achieved with moderate pulse durations (261–508 ns), balancing energy delivery and thermal control. These findings define critical laser parameter thresholds and process windows for the high-speed, high-fidelity cutting of double-coated LiM battery anodes, supporting the industrial adoption of nanosecond laser systems in scalable LMB electrode manufacturing. Full article

Histotripsy is a novel, noninvasive, non-thermal technology invented in 2004 for the precise destruction of biologic tissue. It offers a powerful alternative to more conventional thermal or surgical interventions. Using short-pulse, low-duty cycle ultrasonic waves, histotripsy creates cavitation bubble clouds that selectively and precisely destroy targeted tissue in a predefined volume while sparing critical structures like bile ducts, ureters, and blood vessels. Such precision is of value when treating tumors near vital structures. The FDA has cleared histotripsy for the treatment of all liver tumors. Major medical centers are currently spearheading clinical trials, and some institutions have already integrated the technology into patient care. Histotripsy is now being studied for a host of other cancers, including primary kidney and pancreatic tumors. Preclinical murine and porcine models have already revealed promising outcomes. One of histotripsy’s primary advantages is its non-thermal mechanical actuation. This feature allows it to circumvent the limitations of heat-based techniques, including the heat sink effect and unpredictable treatment margins near sensitive tissues. In addition to its non-invasive ablative capacities, it is being preliminarily explored for its potential to induce immunomodulation and promote abscopal inhibition of distant, untreated tumors through CD8+ T cell responses. Thus, it may provide a multilayered therapeutic effect in the treatment of cancer. Histotripsy has the potential to improve precision and outcomes across a multitude of specialties, from oncology to cardiovascular medicine. Continued trials are crucial to further expand its applications and validate its long-term efficacy. Due to the speed of recent developments, the goal of this review is to provide a comprehensive and updated overview of histotripsy. It will explore its physics-based mechanisms, differentiating it from similar technologies, discuss its clinical applications, and examine its advantages, limitations, and future. Full article