Search Results (440)

The high-efficiency polishing of large-sized polycrystalline diamond (PCD) wafers continues to pose significant challenges in its practical applications. Conventional mechanical polishing suffers from a low material removal rate (MRR) and surface damage. To improve the process efficiency, this study investigates the effect of chemomechanical abrasive polishing (CMAP) with a slurry containing high-concentration H₂O₂ and varying mass percentages of SiO₂ powder and diamond particles on surface morphology, surface roughness, material removal rate (MRR), and microstrain of PCD disks. The contributions of mechanical action, chemical action, and bubble cavitation to the CMAP process are analyzed. Scanning electron microscopy (SEM) observations indicate that large grains present in PCD are effectively eliminated after CMAP, leading to a notable reduction in surface roughness. The optimal results are obtained with 60 wt% SiO₂ powder and 40 wt% diamond particles, achieving a maximum MRR of 1039.78 μm/(MPa·h) (15.5% improvement compared to the mechanical method) and a minimum surface roughness (Sa) of 3.59 μm. Additionally, the microstrain on the PCD disk shows a slight reduction following the CMAP process. The material removal mechanism is primarily attributed to mechanical action (70.8%), with bubble cavitation and chemical action (27.5%) and action of SiO₂ (1.7%) playing secondary roles. The incorporation of SiO₂ leads to the formation of a lubricating layer, significantly reducing surface damage and decreasing the surface roughness Sa to 1.39 µm. 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

To improve environmental sustainability and operational safety in maritime industries, the development of efficient methods for removing biofouling from submerged surfaces is critical. This study investigates the erosion mechanisms of cavitation jets as a non-contact, high-efficiency method for detaching marine organisms, including bacteria and larvae, from ship hulls and underwater infrastructure. Through erosion experiments on coated specimens, variations in jet morphology, and flow visualization using the Schlieren method, we examined how factors such as jet incident angle and nozzle configuration influence removal performance. The results reveal that erosion occurs not only at the direct jet impact zone but also in regions where cavitation bubbles exhibit intense motion, driven by pressure fluctuations and shock waves. Notably, single-hole jets with longer potential cores produced more concentrated erosion, while multi-jet interference enhanced bubble activity. These findings underscore the importance of understanding bubble distribution dynamics in the flow field and provide insight into optimizing cavitation jet configurations to expand the effective cleaning area while minimizing material damage. This study contributes to advancing biofouling removal technologies that promote safer and more sustainable maritime operations. Full article

Cavitation-induced degradation of metallic materials presents a significant challenge for engineers and users of equipment operating with high-velocity fluids. For any metallic material, the mechanical strength and ductility characteristics are controlled by the mobility of dislocations and their interaction with other defects in the crystal lattice (such as dissolved foreign atoms, grain boundaries, phase separation surfaces, etc.). The increase in mechanical properties, and consequently the resistance to cavitation erosion, is possible through the application of heat treatments and cold plastic deformation processes. These factors induce a series of hardening mechanisms that create structural barriers limiting the mobility of dislocations. Cavitation tests involve exposing a specimen to repeated short-duration erosion cycles, followed by mass loss measurements and surface morphology examinations using optical microscopy and scanning electron microscopy (SEM). The results obtained allow for a detailed study of the actual wear processes affecting the tested material and provide a solid foundation for understanding the degradation mechanism. The tested material is the Ni-based alloy INCONEL 625, subjected to stress-relief annealing heat treatment. Experiments were conducted using an ultrasonic vibratory device operating at a frequency of 20 kHz and an amplitude of 50 µm. Microstructural analyses showed that slip bands formed due to shock wave impacts serve as preferential sites for fatigue failure of the material. Material removal occurs along these slip bands, and microjets result in pits with sizes of several micrometers. Full article

This paper investigates the pressure fluctuation characteristics induced by cavitation in the blade-tip region of an axial flow pump through experimental and numerical methods. Compared with previous studies, this research not only analyzes the development of cavitation bubbles under varying flow rates but also explores the transient pressure fluctuation features caused by cavitation. It is found that partial-loading conditions tend to exacerbate cavitation, leading to more pronounced transient flow characteristics. The primary frequency of pressure fluctuations consistently corresponds to the impeller’s rotational frequency and its harmonics, with the magnitude inversely related to flow rate. At the same cavitation stage, lower flow rates exhibit larger amplitudes and more significant fluctuations in high-frequency components. This indicates stronger entrainment disturbance between the cavitation morphology and the mainstream in the blade-tip region at lower flow rates, resulting in more complex flow structures. This study provides a theoretical basis for understanding the mechanisms of pressure fluctuations induced by cavitation in the blade-tip region of axial flow pumps. Full article

Background: Boiling histotripsy (BH) uses high-amplitude, short-pulse focused ultrasound to disrupt tissue mechanically. Oncolytic virotherapy using reovirus has shown modest clinical benefit in pancreatic cancer patients. Here, reovirus and BH were used to treat pancreatic tumours, and their effects on the immune transcriptome of these tumours were characterised. Methods: Orthotopic syngeneic murine pancreatic KPC tumours grown in immune-competent subjects, were allocated to control, reovirus, BH and combined BH and reovirus treatment groups. Acoustic cavitation was monitored using a passive broadband cavitation sensor. Treatment effects were assessed histologically with hematoxylin and eosin staining. Single-cell multi-omics combining whole-transcriptome analysis with the expression of surface-expressed immune proteins was used to assess the effects of treatments on tumoural leukocytes. Results: Acoustic cavitation was detected in all subjects exposed to BH, causing cellular disruption in tumours 6 h after treatment. Distinct cell clusters were identified in the pancreatic tumours 24 h post-treatment. These included neutrophils and cytotoxic T cells overexpressing genes associated with an N2-like and an exhaustion phenotype, respectively. Reovirus decreased macrophages, and BH decreased regulatory T cells compared to controls. The combined treatments increased neutrophils and the ratio of various immune cells to Treg. All treatments overexpressed genes associated with an innate immune response, while ultrasound treatments downregulated genes associated with the transporter associated with antigen processing (TAP) complex. Conclusions: Our results show that the combined BH and reovirus treatments maximise the overexpression of genes associated with the innate immune response compared to that seen with each individual treatment, and illustrate the anti-immune phenotype of key immune cells in the pancreatic tumour microenvironment. Full article

Free stroke, which means the intermittent no-load operation state of dampers, can cause an abnormal noise and unavoidably lead to the deterioration of vehicle NVH performance. In electric vehicles, the noise is particularly intolerable because there are no engine sounds to mask it. Focusing on this, the mechanism of the free-stroke phenomenon is analyzed. A method, which involves parametric models and numerical simulation, is proposed to prevent free-stroke phenomena during the damper design phase. This paper proposes a free-stroke mechanism based on a fluid–structure interaction (FSI) numerical method, combined with experiments, which intends to provide a design reference with guaranteed performance for dampers. Initially, according to parametric cavitation models and by applying numerical methods, simulations for the proposed FSI model are calculated. By analyzing the simulation results, strain variation characteristics near the bottom of the damper valves are revealed, which establish the relationships between strain change, cavitation and the free-stroke phenomena. Meanwhile, the specific position and distribution of free-stroke failure are clearly located by running diverse loading speeds. Finally, all the theoretical analysis results are verified using damper noise tests and indicator bench tests. Full article

Micro-nano bubbles (MNBs) are tiny bubbles with diameters ranging from 200 nm to 30 µm. They possess unique physicochemical properties such as a large specific surface area, slow rising velocity, high gas dissolution rate, high mass transfer efficiency, and strong interfacial zeta potential. These properties endow MNBs with great potential in various fields, including water treatment, enhanced oil recovery, medical and health care, and agriculture. This paper systematically reviews the physicochemical properties, generation methods, and applications of micro-nano bubbles. The main production methods include the mechanical stirring, pressurized dissolved gas release, ultrasonic cavitation, venturi injection, electrolysis, etc. The principles, advantages and disadvantages, and optimization strategies of these methods are comprehensively analyzed. In terms of applications, the mechanisms and typical cases of MNBs in enhanced oil recovery, water treatment, mineral flotation, medical drug delivery, and crop yield enhancement are thoroughly discussed. Extensive research has shown that MNB technology is highly efficient, energy-saving, and environmentally friendly. However, improving bubble stability, generation efficiency, and large-scale application remain key directions for future research. Full article

Nickel aluminum bronze (NAB) and manganese aluminum bronze (MAB) are widely used in propulsion and seawater handling systems in naval platforms due to their attractive combination of mechanical strength, toughness, and very low susceptibility to marine corrosion. Nevertheless, it is well known that they can suffer from selective phase corrosion and erosion–corrosion, primarily caused by cavitation and sand erosion. Both alloys have a multiphase microstructure that governs their mechanical and chemical behavior. The tribocorrosion behavior of cast NAB and MAB alloys was studied in artificial seawater to analyze the effect on microstructure. The microstructure and nanohardness were evaluated and correlated with tribocorrosion test results conducted under two different loads (10 and 40 N) in a unidirectional sliding mode using a 1 M NaCl solution as the electrolyte. A significant increase in the corrosion rate due to the wear effect was observed in both alloys. MAB exhibited a slightly better tribocorrosion performance than NAB, which was attributed to significant differences in the shape, distribution, and size of the intermetallic kappa phases—rich in iron, aluminum, and nickel—within the microstructure. Pitting corrosion was observed in NAB, while selective corrosion of kappa phases occurred in MAB, highlighting the role of the protective layer in the tribocorrosion behavior of both alloys. These findings were supported by post-test solution analysis using ICP-AES and corrosion product characterization by EDX. A synergistic effect between wear and corrosion was confirmed for both alloys, as erosion removes the protective layer, exposing fresh material to continuous friction and favoring a progressive material loss over time. The practical impact of this study lies in improving the control and design of highly alloyed bronze microstructures under in-service corrosion–erosion conditions. Full article

The upstream pumping effect of mechanical face seals has a significant influence on their sealing performance. In order to reveal the effect of deep grooves on upstream pumping effects, an experimental and theoretical analysis is carried out in this study. The main novelty of this paper is to analyze the feasibility of deep grooves in a mechanical seal design from the perspective of cavitation and leakage rate. Firstly, an upstream pumping spiral groove is designed and fabricated, with different groove depths from 2 μm to 90 μm. Then, testing is performed with water as the sealing medium. Finally, the cavitation phenomena are captured, and leakage rates are measured during the experiment. The obtained results show that the groove with a depth of tens of microns can be designed according to the laminar flow hypothesis, and Reynolds equation is still valid to predict the cavitation and leakage rate theoretically. The spiral groove with a depth of tens of microns shows a significant upstream pumping effect. Both the theoretical and experimental analyses show that under certain working conditions, deep grooves can realize the zero-leakage sealing design of liquid, which might provide significant guidance for the sealing design of mechanical face seals to enhance sealing performance. Full article

The influence of multiwall carbon nanotube (MWCNT) reinforcements on electrochemical corrosion investigations at varying NaCl concentrations (0.4 M, 0.6 M, 0.8 M, 1 M) of Mg-Zn-Ce nanocomposites is studied in this work. The Mg-Zn-Ce/MWCNT nanocomposites were developed by using an ultrasonication-assisted hybrid stir–squeeze (UHSS) casting method with different MWCNT concentrations (0, 0.4, 0.8, 1.2 wt.%) in a Mg-Zn-Ce magnesium alloy matrix. The microstructural characterizations shown using X-ray diffraction revealed the presence of secondary phases (MgZn₂, Mg₁₂Ce), T-phase (Mg₇Zn₃RE), α-Mg, and MWCNT peaks. Optical microscopy results showed grain refinement in the case of nanocomposites. Transmission electron microscope studies revealed well-dispersed MWCNT, indicating the good selection of processing parameters. The uniform dispersion of MWCNTs was achieved due to a hybrid stirring mechanism along with transient cavitation, ultrasonic streaming, and squeeze effect. The higher E_corr value of −1.39 V, lower I_corr value (5.81 µA/cm²), and lower corrosion rate of 0.1 mm/Yr (↑77%) were obtained by 0.8% nanocomposite at 0.4 M NaCl concentration, when compared to the monolithic alloy. The Mg(OH)₂ passive film formation on 0.8 wt.% nanocomposite was denser, attributed to the refined grains. At higher NaCl concentration, the one-dimensional morphological advantage of MWCNT helped to act as a barrier for further Mg exposure to excessive Cl⁻ attack, which reduced the formation of MgCl₂. Therefore, the UHSS-casted Mg-Zn-Ce/MWCNT nanocomposites present a good potential as sacrificial anodes for use in a wide range of industrial applications. Full article

Background: Influenza B usually causes mild illness in children. Severe and fatal cases can occur when complicated by secondary Staphylococcus aureus (S. aureus) pneumonia, including community-acquired methicillin-resistant Staphylococcus aureus (MRSA). We present a rare, rapidly progressive fatal case in an adolescent with no known medical history to highlight diagnostic and therapeutic pitfalls. Case Presentation: A 16-year-old boy with no known underlying conditions (unvaccinated for influenza) presented critically ill at “Sf. Ioan” Clinical Emergency Pediatric Hospital in Galați after one week of high fever and cough. He was in respiratory failure with septic shock, requiring immediate intubation and vasopressors. Chest X-ray (CXR) showed diffuse bilateral infiltrates (acute respiratory distress syndrome, ARDS). Initial laboratory tests revealed leukopenia, severe thrombocytopenia, disseminated intravascular coagulation (DIC), rhabdomyolysis, and acute kidney injury (AKI). Reverse transcription polymerase chain reaction (RT-PCR) confirmed influenza B, and blood cultures grew MRSA. Despite maximal intensive care, including mechanical ventilation, antibiotics (escalated for MRSA), antiviral therapy, and cytokine hemoadsorption therapy, the patient developed refractory multi-organ failure and died on hospital day 6. Autopsy revealed bilateral necrotizing pneumonia (NP) without radiographic cavitation, underscoring the diagnostic challenge. Discussion: The initial chest radiography showed diffuse bilateral pulmonary infiltrates, predominantly in the lower zones, with an ill-defined, patchy, and confluent appearance. Such appearance, in our case, was more suggestive of rapid progressive NP caused by MRSA rather than the typical pneumococcal one. This is one of the few reported cases of influenza B–MRSA coinfection with fulminant rhabdomyolysis and autopsy-confirmed necrosis. Our fulminant case illustrates the synergistic virulence of influenza and MRSA. Toxin-producing MRSA strains can cause NP and a “cytokine storm,” causing capillary leak, ARDS, shock, and DIC. Once multi-organ failure ensues, the prognosis is grim despite aggressive care. The absence of early radiographic necrosis and delayed anti-MRSA therapy (initiated after culture results) likely contributed to the poor outcome. Conclusions: Influenza B–MRSA co-infection, though rare, demands urgent empiric anti-MRSA therapy in severe influenza cases with leukopenia or shock, even without radiographic necrosis. This fatal outcome underscores the dual imperative of influenza vaccination and early, aggressive dual-pathogen targeting in high-risk presentations. Full article

Ultrasound technology has emerged as a transformative tool in modern food science, offering non-destructive, real-time assessment and enhancement of food quality attributes. This review systematically explores the fundamental mechanisms by which ultrasound interacts with food matrices, including mechanical effects such as acoustic cavitation, localized shear forces, and microstreaming, as well as thermal and acoustic attenuation phenomena. Applications of ultrasound in food texture evaluation are discussed across multiple sectors, with particular emphasis on its role in assessing moisture distribution, fat content, structural integrity, and microstructural alterations in meat, dairy, fruits, and vegetables. The versatility of ultrasound—spanning low-intensity quality assessments to high-intensity processing interventions—makes it an invaluable technology for both quality control and product innovation. Moreover, emerging innovations such as ultrasound-assisted extraction, non-thermal pasteurization, and real-time quality monitoring are highlighted, demonstrating the synergy between ultrasound and advanced technologies like AI-driven data interpretation and portable, handheld sensing devices. Despite these advances, challenges related to technical limitations in heterogeneous food systems, high initial investment costs, scalability, and the absence of standardized protocols remain critical barriers to widespread adoption. The future directions emphasize the integration of ultrasound with multi-modal approaches, the development of miniaturized and cost-effective equipment, and the establishment of global regulatory standards to facilitate its broader application. Overall, ultrasound is positioned as a key enabler for sustainable, efficient, and non-invasive quality assurance across the global food industry. Full article

In this study, cavitation erosion tests were conducted to investigate the effects of the presence of coolant additives and chlorides on the corrosion and cavitation erosion of cylinder liners in marine diesel engines. Electrochemical experiments were conducted to evaluate the corrosion characteristics of ductile cast iron (DCI), and the corrosion potential and corrosion current density were measured. In addition, weight loss, surface roughness, and maximum surface damage depth were quantified as a function of cavitation exposure time. Furthermore, to investigate the erosion and erosion–corrosion characteristics induced by cavitation attack, the damaged surface morphology was closely examined using a scanning electron microscope (SEM) after the cavitation erosion tests. The results revealed that the coolant additive effectively protected the DCI from corrosion caused by aggressive chlorides. In particular, when an appropriate amount of additive was added to a coolant containing 100 ppm of chloride, the corrosion current density of DCI was reduced by approximately 31.7 times, significantly improving corrosion resistance. Therefore, different surface damage mechanisms corresponding to cavitation erosion and cavitation erosion–corrosion were identified depending on the presence or absence of the coolant additive during the cavitation erosion tests. Full article

Soft lithography with microfabricated molds is a widely used manufacturing method. Recent advancements in 3D printing technologies have enabled microscale feature resolution, providing a promising alternative for mold fabrication. It is well established that the curing of PDMS is influenced by parameters such as temperature, time, and curing agent ratio. This study was conducted to address inconsistencies in PDMS curing observed when using different 3D-printed mold materials during the development of a Lab-on-a-Chip (LoC) system, which is typically employed for investigating the effect of hydrodynamic cavitation on blood clot disintegration. To evaluate the impact of mold material on PDMS curing behavior, PDMS was cast into molds made from polylactic acid (PLA), polyethylene terephthalate (PET), resin, and aluminum, and cured at controlled temperatures (55, 65, and 75 °C) for various durations (2, 6, and 12 h). Curing performance was assessed using Soxhlet extraction, Young’s modulus calculations derived from Atomic Force Microscopy (AFM), and complementary characterization methods. The results indicate that the mold material significantly affects PDMS curing kinetics due to differences in thermal conductivity and surface interactions. Notably, at 65 °C, PDMS cured in aluminum molds had a higher Young’s modulus (~1.84 MPa) compared to PLA (~1.23 MPa) and PET (~1.17 MPa), demonstrating that the mold material can be leveraged to tailor the mechanical properties. These effects were especially pronounced at lower curing temperatures, where PLA and PET molds offered better control over PDMS elasticity, making them suitable for applications requiring flexible LoC devices. Based on these findings, 3D-printed PLA molds show strong potential for PDMS-based microdevice fabrication. Full article