Local Heating Effect Research Articles

Unconventional mechanical responses and mechanisms of Ti-6Al-4V sheet subjected to electrically-assisted cyclic loading-unloading: Thermal and athermal effects

For the sake of unveiling the macro-micro behaviors and underlying control mechanisms of electroplastic effect (EPE) of sheet metals during recent thriving electrically-assisted incremental forming (EAIF) processes, electrically-assisted cyclic loading-unloading tension (EACT) experiments were carried out at a current density of 14～20A/mm2 followed by forced and unforced cooling. The electro-thermo-mechanical responses and the evolution rules of dislocation configurations, fracture modes, phase composition and local orientation distribution were characterized by IR imaging, SEM, quantitative EBSD and TEM tests. Moreover, the thermal and athermal components of the electrically-induced stress drop throughout the EACT processes were decoupled and systematically analyzed via temperature control tests and isothermal correction. The results show that thermal effect of electric current possesses a great proportion of 75 % in the overall stress drop and plays a key role in elastic modulus degradation and ductility enhancement by activating pyramidal {101‾1}⟨12‾10⟩ slip systems, weakening (0001) texture and promoting dynamic recrystallization (DRX) and α→β→α′ phase transformation. While the athermal effect only operates after reaching both threshold current density and plastic strain, it increases monotonically with current density, brings about “hot spots” effect, local charge imbalance and weakened atomic bonding, and further causes intensified local strain gradient, substructure formation and DRX nucleation. The ratio of athermal stress drop first decreases and then increases significantly with loading cycle at the later stage of EACT under the combined effect of local Joule heating effect and flow localization. Additionally, the athermal effect only activates short-range solute diffusion and localized diffusional α→β phase transformation, while the combined thermal and athermal effects promote long-range solute diffusion and an increasing rate in β content of 261.8 %. The present work provides theoretical basis for optimizing the EAIF forming process and realizing extreme manufacture of light-weight thin-walled complex components.

Microstructure Evolution and Mechanical Properties of In Situ TiB2/Al–Zn–Mg–Cu Composites by Electropulsing‐Assisted Solution Treatment

The traditional solution treatment is not completely applicable for in situ TiB2/Al–Zn–Mg–Cu composite due to the influence of TiB2 particles. This study investigates the impact of the electropulsing‐assisted solution (EAS) process on the microstructure evolution and mechanical properties of TiB2/Al–Zn–Mg–Cu composites. The nonuniform microstructure evolution related to the difference in temperature and current density is supported by simulative and experimental results. EAS treatment significantly enhances the degree of supersaturation, allowing phases surrounding TiB2 particles to dissolve without extensive overburning, unlike traditional solution treatments. This improvement is attributed to the reduced thermodynamic barrier and accelerated atomic diffusion, facilitated by both localized and average Joule heating effects and enhanced thermal electron/phonon scattering. Meanwhile, grain size remains stable during the temperature rise induced by EAS treatment. Furthermore, the mechanical properties of composites increase, among which the increase in strength is mainly ascribed to solid–solution strengthening, and the increase in elongation is related to multiple factors referring to TiB2 particles fracture and interface crack between the undissolved phases and matrix. This study provides an approach to achieve an efficient dissolution of phases aggregated with particles and without widespread overburning in particle‐reinforced Al matrix composites via electropulsing techniques.

Rapid detection of benzoic, sorbic, and dehydroacetic acids in processed foods using surface-enhanced Raman scattering spectroscopy

Benzoic acid (BA), sorbic acid (SA), and dehydroacetic acid (DHA) are among the most common food additives that are classified as antimicrobial preservatives. However, their consumption in excess can lead to damage to the human liver and kidneys. At the present time, no rapid method has been developed for the simultaneous detection of these preservatives in processed foods. In this study, an expedited process based on surface-enhanced Raman scattering (SERS) and solid-phase extraction (SPE) has been developed to determine the content of the preservatives in processed seafood, minced fish, and cheese products. The effect of local heating on SERS spectra at the center of the droplet, which was deposited onto silver nanopillar arrays used as the SERS substrate, was examined. A recirculating flow, manifested as twin vortices merging within the droplet, brought the preservative molecules down to the droplet’s center, resulting in an increase in the SERS signals. Furthermore, the screening efficiency of the detection method for the three preservatives was experimentally evaluated in real samples. The experimentally determined Raman bands of the added BA, SA, and DHA were compared with amounts obtained by the conventional method of high-performance liquid chromatograph (HPLC).

Construction of bilayer cellulose-based aerogel with salt-resistant design for efficient solar desalination and wastewater purification

Solar-driven interfacial evaporation (SDIE) technology, which utilizes green and renewable solar energy to produce clean water, has shown great potential in alleviating global water scarcity. However, practical applications still face numerous challenges, including salt crystallization precipitation and accumulation, low energy utilization, and complex preparation processes. Hence, We designed a vertically ordered porous bilayer aerogel based on nanofibrillated cellulose (NFC)/polyethyleneimine (PEI) with excellent salt resistance, light absorption and local thermal effects to achieve efficient solar steam generation. Specifically, the photothermal conversion layer (PCL) at the top had excellent light absorption and photothermal conversion efficiency by introducing graphene oxide (GO) as a highly efficient photothermal material. The water transport layer (WTL) at the bottom ensured a stable water supply to the evaporation layer by virtue of the vertical water transfer path and inherent hydrophilicity, and effectively prevented formation of salts in the evaporation area. In addition, the designed aerogel had a low thermal conductivity, which achieved effective thermal insulation and further enhanced the localized heating effect. This superhydrophilic bilayer aerogel achieved a high evaporation rate of 1.9596 kg m−2 h−1 and an energy conversion efficiency of 92.28% under one solar irradiation. It is noteworthy that evaporation process exhibited excellent stability during 8 h of continuous evaporation in 20 wt% brine and no salt accumulation was observed on the evaporated surface. In addition, the bilayer aerogel demonstrated excellent long-term stability and self-cleaning. Meanwhile, its excellent anti-contamination and wastewater treatment capabilities give SDIE technology a stable and continuous operation in practical applications, thus demonstrating significant application potential.

Electroplasticity mechanism of Ti2AlNb alloys under hot compression with the application of a lower electric current

In this study, a lower electric current (1.0–2.0 A/mm2) was applied during hot compression of Ti2AlNb alloys, and the mechanical response, microstructure evolution, and electroplasticity mechanism were investigated. The results showed that the maximum flow stress drop could reach 18.7 % after applying a lower electric current of 2.0 A/mm2, which confirms the existence of electroplasticity. The stress drop increased with increasing electric current density. However, the flow stresses of the samples in the isothermal compression test and those subjected to a 1.0 A/mm2 electric current compression test were similar, indicating that there is a threshold value for the electroplasticity effect on flow stress. The lower strain hardening rate caused by the electric current confirmed the electroplasticity effect, promoting the softening effect. Additionally, the lower average activation energy Q, affected by the electric current, implied the improvement of the deformability of the alloy due to the deformation mechanism of dynamic recovery (DRV), dynamic globularization, or dynamic recrystallization (DRX). The gradual reduction of dislocation density with increasing electric current density resulted in the stress drop, which can be ascribed to the directional drifting electrons colliding with dislocations, which promoted the movement of dislocations by arranging the dislocations in parallel. The local high temperature induced by the local Joule heating effect at the O lamella had a strong promoting effect on the globularization of the O lamella by producing uniform lattice distortion/local strain at the O/B2 interface. With increasing furnace temperature, the drifting electrons accelerated the transformation of LAGBs to HAGBs which promoted the appearance of dynamic recrystallization grains.

Computational insights from the thermal spike model into mesoporous silica behavior during swift heavy ion irradiation

Mesoporous silica materials are pivotal in various scientific domains due to their unique properties and versatile applications. However, understanding their response to irradiation, particularly from Swift Heavy Ions (SHI), remains limited. We address this gap by investigating experimental mesoporous silica behavior under 12 MeV Carbon and 92 MeV Xenon bombardment using the Three-Dimensional Thermal Spike Model (3DTS) simulation. Our computational simulations reveal localized heating effects and provide mechanistic insights into experimental observations, shedding light on pore closure and different observed damage patterns. This study is the first application of this model to porous silica and deepens our knowledge of the mechanism of structural evolution under ion bombardment.

Photo-Fenton-Active MIL-88A/CNT-Based PVA Hydrogel for Solar-Driven Water Evaporation and Simultaneous Volatile Organic Compound Removal.

Solar-driven interfacial water evaporation (SIWE) has emerged as a promising avenue for cost-effective freshwater production from seawater or wastewater. However, the simultaneous evaporation of volatile organic compounds (VOCs) presents a limitation for the widespread implementation of this technique. Thus, developing dual-functional evaporators capable of both desalining seawater and degrading VOCs is challenging. Herein, we fabricated an iron-based metal-organic framework MIL-88A/carbon nanotubes (CNTs) poly(vinyl alcohol) hydrogel (MCH) evaporator via the conventional freezing method for solar-driven seawater desalination and simultaneous photo-Fenton VOC degradation. Because of the superior photothermal conversion capability of CNTs, reduced thermal conductivity and water evaporation enthalpy within the hydrogel, and the photo-Fenton activity of rod-shaped MIL-88A, the MCH evaporator exhibits a higher evaporation rate of 2.26 kg m-2 h-1 under 1 sun illumination with simultaneous VOC degradation. The higher hydrophilicity and vertical channels in the MCH evaporator enable its self-salt cleaning ability, facilitating consistent seawater desalination, even in high salt concentrations up to 10 wt %. The synergistic effects of localized heating from CNTs and hydrogen peroxide activation through reactive sites of MIL-88A allow the MCH evaporator to degrade more than 93% of the added phenol during evaporation. This work presents a sustainable and efficient approach for solar-driven seawater desalination, offering simultaneous VOC degradation.

Effects of Local Heating and Whole-Body Hyperthermia on Neuromuscular and Cognitive Function in Young and Old Healthy Adults

Background and objectives: Aging population is growing fast in European Union and worldwide (Shimizu et al., 2020). A progressive decline in neuromuscular function (Lexell et al., 1983), structural changes in the brain ( Smith et al., 2010; Zahra et al., 2019)aged 30 to 99 years, were studied with MRI. Age was related to estimated volumes of: gray matter, white matter, and CSF of the cerebrum and cerebellum; gray matter, white matter, white matter abnormality, and CSF within each cerebral lobe; and gray matter of eight subcortical structures. The results were: 1, and inefficiencies in thermoregulatory regulation (Blatteis, 2012; Yamashiro et al., 2020) were found in the old population. We conducted three experiments to investigate the effects of short-term and long-term passive heating on motor performance, as well as the impact of whole-body passive heating on cognitive functioning in both healthy older and young adults. Methods: In the first study, weight (kg), body fat (%), height (cm), body mass index (BMI), skinfold thickness (mm), and the mean subcutaneous fat thickness were calculated (McArdle et al., 1984). Ankle muscle torque production and contractile properties were determined by isometric torque of the ankle plantar flexion and the isokinetic (dynamic) torque of the ankle plantar flexion/dorsiflexion muscles using an isokinetic dynamometer (System 4; Biodex Medical Systems, Shirley, NY, USA). In the second study, body surface area, heart rate, muscle temperature, and thermal sensation were measured. Prolactin, interleukin-6, dopamine and cortisol concentrations were obtained via venous blood samples. The isometric torque of ankle plantar flexion muscles was assessed as the first study. In the third study, body weight, sweating rate, rectal temperature, heart rate, physiological strain index (PSI), thermal sensations were investigated. A programmed cognitive test to assess cognitive functioning (Brazaitis et al., 2015). Results: In the first study, for the older adults (vs. younger adults), the application of local heating (vs. control trial) was accompanied by a significant increase in maximal voluntary peak torque, rate of torque development, and isokinetic peak torque of plantar flexion/dorsiflexion muscle contraction. In the second study, older males demonstrated greater neuromuscular fatigability resistance and faster maximal voluntary contraction (MVC) torque recovery after a 2-min sustained isometric MVC task under thermoneutral and severe hyperthermic conditions. In the third study, PSI was lower and cortisol concentration was greater after whole-body heating in the older group compared with the younger group. Surprisingly, hyperthermia improved cognitive flexibility only in old adults, whereas short-term and visual recognition memories were maintained in both age groups. Conclusions: In the first study, the spinal and supraspinal reflex excitability of older adults increased during local knee-heating application. The improved motor drive transmission observed in older adults was accompanied by increased voluntarily induced torque production of the ankle muscles during isometric/isokinetic contractions. In the second study, neuromuscular performance during fatigue-provoking sustained isometric exercise under severe whole body hyperthermia conditions appears to decline in both age groups, but a lower relative decline in torque production for older males may relate to lower psychological and thermophysiological strain along with a diminished dopamine response and prolactin release. In the third study, A ≈ 2.5 ◦C increase in rectal temperature can improve executive function in old adults, and this increase parallels the increased cortisol concentration and the lower thermophysiological strain under severe whole-body hyperthermia conditions.

Flash joining of (La0.2Nd0.2Sm0.2Gd0.2Yb0.2)2Zr2O7 high-entropy ceramic to 3YSZ

(La0.2Nd0.2Sm0.2Gd0.2Yb0.2)2Zr2O7 high-entropy ceramic (HEC) and 3 mol% yttria-stabilized zirconia were directly joined in seconds using an innovative pressure-assisted flash joining technique. An optimized shear strength of 26 ± 3 MPa was obtained at 1200 °C under uniaxial pressure of 9 MPa in 30 s. The contact resistance at the interface was found to induce intense local Joule heating, which accelerated interfacial mass transport and the joining process. However, this local heating effect also led to segregation and precipitation of the HEC near the interface, forming large La/Yb-rich rare-earth zirconate grains and intergranular pores. Increasing the pressure inhibited these issues by lowering the contact resistance, suppressing grain growth, and promoting grain sliding, rearrangement, and coalescence of grain boundaries. The proposed mechanism, based on the local heating effect, provides new insights into flash joining, highlighting the critical role of this phenomenon in triggering thermal runaway and mass transport.

Mechanical behavior and underlying mechanism of nickel-based superalloy during coupling electrical pulse and ultrasonic treatment

Coupling electric pulse and ultrasonic treatment (CEPUT) is a multi-energy field-assisted forming technology that can improve the forming efficiency of materials. The current research focused on the surface modification of materials by CEPUT, lacking the explanation of its coupling mechanism. In this study, Inconel 718 was adopted as the research object to observe the mechanical behavior and microstructure after CEPUT uniaxial tension experiment. The deformation tendency of grain under coupling multi-energy field was described by analyzing the texture evolution and dislocation morphology. The coupling mechanism of ultrasonic vibration and pulsed current was revealed in CEPUT. The experimental results revealed that there was a nonlinear relationship between the increase of flow stress softening efficiency and the increase of ultrasonic energy density and current density. This phenomenon was the macroscopic manifestation of interference between initial ultrasonic vibration and vibration after energy attenuation, which was related to dislocation slip and recrystallization under coupled multi-field. In addition, more efficient path of dislocation slip was demonstrated through the CEPUT. Among them, ultrasonic vibration caused local resistance to rise at the dislocation source and dislocation pile-up, which strengthened the local Joule heating effect; while the pulsed current reduced the activation energy required for dislocation slip near the waning points. This effectively reduced the resistance of dislocation motion near the pinning point, promoting the chance of dislocation crossing and annihilation. Meanwhile, the high temperature caused by pulsed current and local high strain caused by ultrasonic vibration were more favorable to dynamic recrystallization, and the change of grain orientation was more active. The texture strength and grain orientation of the matrix can be effectively controlled by adjusting the input power of ultrasonic vibration and pulsed current.

Construction of robust silica-titania polydopamine composite membrane with light-absorption property for photothermal vacuum membrane distillation

A robust silica-titania polydopamine composite membrane was fabricated adding a photothermal polydopamine coating to the surface of polypropylene membrane for photothermal vacuum membrane distillation. Detailly, the surface of an inert PP membrane was modified with atomically controllable titanium and silicon to enhance the hydroxyl groups on the membrane surface, then, a photothermal effect layer of polydopamine was generated on the composite membrane surface through the self-polymerization reaction of dopamine. The polydopamine coating has significant light absorption and heating properties, and it can act as a local heater when exposed to light sources. This local heating effect significantly raises the temperature at the membrane interface, creating a thermal gradient that drives the evaporation of water molecules. Specifically, we quantitatively analyzed the three reasons (surface energy, free radicals, and photothermal effect) for the increase in evaporation rate of the pristion PP membrane caused by the membrane composite membrane. Among these reasons, the photothermal effect caused by black polydopamine is the most important factor for improving evaporation efficiency. The dark-illumination alternating experiment revealed that the PP-TiO2-SiO2-PDA composite membrane delivered a noteworthy enhancement in vacuum membrane distillation performance (approximately 40%), while the improvement of the PP membrane was only 1.7%.

Au@AgPt core/cage nanoframes as photothermal catalyst for enhanced NIR-induced 4-nitrophenol reduction

The selection and optimization of catalysts have been a subject of considerable research interest in recent decades. Bimetallic and multimetallic nanocatalysts, comprised of plasmonic and catalytic components, have recently emerged as a promising approach to achieving high catalytic performance due to synergistic effects. In this study, an Au@AgPt core/cage nanoframe has been successfully fabricated. It features a controllable hollow silver-platinum alloy nanoframe with an in-built plasmonic gold nanorod, serving as a plasmon-enhanced photothermal catalyst for the reduction of 4-nitrophenol (4-NP). This well-designed trimetallic nanostructure exhibits a unique core-cage nanoframes structure and surface roughness, offering advantages in both composition and structure. The LSPR-excited local heating effect and hot-electron generation, as well as the intrinsic catalytic active sites, work synergistically and are highly beneficial for temperature-sensitive reaction of 4-NP reduction. Experimental results have shown that the optimized nanocatalysts of Au@AgPt-4, featuring an optimal Pt content and robust photothermal performance, display stable photothermal catalytic properties and the best photothermal catalytic performance compared with other nanostructures, completing the reduction reaction within approximately one minute. This study provides a rational design of nanoscale materials with plasma-enhanced properties, which can help to inspire further catalyst design and optimization.

Formation of ferromagnetic Fe5Se8 via phase transition and enhanced hydrogen evolution reaction with alternating magnetic fields

Leveraging alternating magnetic fields (AMFs) to induce localized heating in catalysts has emerged as a powerful approach to boost electrocatalytic reactions. However, the rational design and synthesis of ferromagnetic catalysts that can be stably coupled with an AMF to improve the hydrogen evolution reaction (HER) performance are still urgent and challenging. Herein, the ferromagnetic triclinic Fe5Se8 has been realized through the phase transition from nonmagnetic orthorhombic FeSe2 synergistically triggered by the selenium vacancies and the strain engineering, making it a good candidate for AMFs-assisted HER. Experimental results and theoretical calculation demonstrate that the phase transition-prepared ferromagnetic Fe5Se8 exhibits much better HER performance than nonmagnetic FeSe2. More importantly, under high-frequency AMF stimulation, the HER performance of ferromagnetic Fe5Se8 is greatly enhanced (the overpotential decreased by 63 mV), which is mainly attributed to the localized magnetic heating effect. This study realizes the controlled phase transition synthesis of ferromagnetic catalysts, indicating that AMF is an effective approach to manipulate the performance of ferromagnetic catalysts.

Non-uniform microstructure evolution rules and mechanisms of Ti55 alloy with initial basket-weave structure during electrically-assisted V bending

Electrically assisted V-bending (EAVB) experiments of Ti55 alloy sheets with initial basketweave structure were carried out at effective current densities of 3–5A/mm2. The history of temperature field, microstructure patterns and mechanical properties were characterized by IR imaging, OM, EBSD and hardness tests. The results show that α lamellae continuously decrease in thickness (from 2.38 μm to 0.64 μm) with increasing current density. The microstructure patterns of the three deformation zones are significantly different due to different deformation mode and electro-thermo-mechanical routes. Due to limited plastic strain, the orientation rotation and shear fracture of the α lamellae are restricted in the neutral layer, while the ones in the inner and outer layers are refined and become more uniform at mild current density. With increasing current density, the main deformation mode of α grains in the inner layer is {1010} prismatic slip and dynamic spheroidization/recrystallization tends to occur at α lamellae with <0110>α//TD orientation. In the neural and outer layer, intense local Joule heat effect induces α→β→α′ phase transformation in “hot spots”, leading to massive growth of 3 variant needle-like α′, intensified heterogeneous micro-deformation and significant strengthening effect. The combined effects of local Joule heat, residual α phase and deformation-induced defect nucleation break the strict Burgers orientation relationship between α/α’ lamellae and β matrix during EAVB and subsequent cooling process.

Effect of local heating on couplings between cardio-respiratory and peripheral oscillations in type 2 diabetes mellitus

Effect of local heating on couplings between cardio-respiratory and peripheral oscillations in type 2 diabetes mellitus

Ni-based plasmonic photocatalysts for solar to energy conversion: A review

Plasmonic-based semiconductors are compelling contenders of current research endeavors to drive chemical reactions via plasmonic and phononic light-matter interactions. Among various plasmonic metals, Ni as a non-precious metal has been extensively studied due to its ability to participate in interband excitation and comparable metal-hydrogen binding energy to that of noble metals including Pt and Ag. The phenomenally high charge-carrier density in photoexcited Ni-based plasmonic nanomaterials offers photochemical conversion of high-energy chemical bonds accompanied by thermal effect. Since the research on the plasmonic activity of the non-precious metal is still emerging, no comprehensive review has addressed the significance of Ni as a plasmonic photocatalyst to the best of our knowledge. This review article sums up the recent progress in the field of plasmonic photocatalysis focusing on Ni-based photocatalysts. The basic principles of the plasmonic effect have been presented, along with an explanation of why Ni may be a viable option. Ni has been investigated for use as a co-catalyst and plasmonic photocatalyst in composite photocatalysis to achieve an accelerated process. After the energy transfer mechanism has been assessed, the review covers the state-of-the-art of two significant effects—plasmon energy transfer and the localized heating effect that are responsible for increased efficiency in energy production. In conclusion, we have included a synopsis of the assessment and emphasized the problems that must be resolved before the technology can be made available for purchase. In a nutshell, the chemistry of plasmonic photocatalysis is promising; but acquiring a detailed mechanism of charge transfer and utilization of charge carriers is still a roadblock in apprehending the full potential of plasmonic photocatalysis. Therefore, this study aims to motivate the scientific community to envision impactful work in the creation of next-generation plasmonic photocatalysts.

Anomalous enhancing effects of electric pulse treatment on strength and ductility of TC17 linear friction welding joints

Mechanical properties of TC17 titanium alloy undergo a significant reduction after linear friction welding (LFW), of which the strength and ductility are hard to be improved simultaneously by traditional aging heat treatment (AHT), seriously limiting the application of LFW in the manufacturing of TC17 titanium alloy blisks. To this end, the present work proposes to use electric pulse treatment (EPT) to enhance the strength and ductility of TC17 LFW joints simultaneously by improving its microstructure. The results show that, in comparison to the uneven distribution of α phases in the welding zone (WZ), heat-affected zone (HAZ), and base metal (BM) zone after AHT, EPT can selectively homogenize the α phase distribution of WZ and HAZ without impacting the BM. The selective effect of EPT is reflected as the synergistic influence of the local Joule heating effect and the electron wind effect, which promotes the diffusion of β phase stabilizing element Mo and leads to a competitive precipitation of β phase and α phase in the α phase transition temperature range. The ratio of α phase to β phase in the WZ and HAZ finally approaches an equilibrium point which is similar to that of BM, leading to a uniform distribution of α phase and realizing the synergy of strength-ductility of LFW joint: the maximum strength increase observed is 12.9 %, accompanied by a corresponding elongation increase of 122 % (by AHT & EPT), and the maximum plasticity improvement is 185 %, accompanied by a corresponding strength increase of 4.3 % (by EPT for 1 h). This study provides essential insights for improving the strength and ductility of LFW TC17 titanium alloy blisks and enhancing the applications of LFW in aeroengine components.

Electropulsing-enhanced atomic diffusion and recrystallization to optimize mechanical properties of Al/Cu laminated metal composites

This work adopted the combined processing of electropulsing bonding (EPB) and electropulsing rolling (EPR) to prepare high-performance Al/Cu laminated metal composites (LMCs). The results show that electropulsing (EP) significantly accelerates the diffusion of Al and Cu atoms, thus facilitating the formation of diffusion layer. Through EP treatment, the recrystallization behavior of the Al and Cu layers is enhanced. The microstructure composed of a diffusion layer with suitable thickness and fine recrystallized grains contributes to the mechanical properties. Due to the introduction of intermetallic compounds (IMCs), the hardness and elastic modulus of Al, Cu, and diffusion layers exist large differences. The hard diffusion layer can exert a rigid deformation constraint on the ductile Al and Cu layers, and promote the interface deformation. Meanwhile, the tensile strength of as-EPRed samples increases and then decreases with the increasing EP frequency, the maximum is ∼215.2 MPa at 20 kHz. Theoretical analysis indicates that the local Joule heating and athermal effect should be the principal factors for microstructure evolution and property optimization. These results are expected to clarify the EP-related mechanism on atomic diffusion and recrystallization, which provides guidance for the fabrication of Al/Cu LMCs.

Impact of Nanoheater Subcellular Localization on the Antitumor Immune Efficacy of Magnetic Hyperthermia

Magnetic nanoparticles (MNPs)-mediated magnetic hyperthermia therapy is garnering attention as a promising modality for tumor remission. This therapy combines localized nano-scale heating and reactive oxygen species-related immunologic effects. A critical aspect in optimizing this therapy involves understanding how nanoheaters’ subcellular localizations influence the therapeutic efficacy and immunological effects of magnetic hyperthermia. Herein, we investigate these effects by focusing on the strategic localization of ferrimagnetic vortex-domain iron oxide (FVIO) nanorings within lysosomes and the cytoplasm of hepatocellular carcinoma (HCC) cells. The comparative analysis revealed that lysosomal-localized magnetic hyperthermia markedly increased apoptosis in Hepa1–6 cells and effectively induced immunogenic cell death (ICD). Mechanistically, lysosomal-localized magnetic hyperthermia led to Bid-associated apoptosis and caspase-1-dependent interleukin-1β (IL-1β) secretion, likely due to enhanced lysosomal membrane permeabilization. Moreover, it reduced calreticulin degradation and increased its presence at the cell membrane, thereby boosting ICD efficiency. In contrast, cytoplasmic-localized magnetic hyperthermia showed comparatively lesser impact than its lysosomal-localized counterpart. In vivo experiments reinforced the exceptional efficacy of lysosomal-localized magnetic hyperthermia, which notably enhanced dendritic cells activation and T cells infiltration in both tumors and lymph nodes, thereby triggering a robust antitumor immune response. Additionally, lysosomal-localized magnetic hyperthermia improved tumor vaccine efficacy and demonstrated the potential for sustaining long-term immune responses in antitumor treatments. This study highlights the crucial role of subcellular positioning of magnetic nanoheaters in determining the efficacy of antitumor immunological responses in magnetic hyperthermia therapy, offering valuable insights for future cancer treatment strategies.

Local laser heating effects in diamond probed by photoluminescence of SiV− centers at low temperatures

The accurate measurement of thermal conductivity of diamond below 10 K has always been a challenge, mainly due to significant error in temperature sensing using the thermocouple method. Diamond is generally considered to have high thermal conductivity, so little attention has been paid to the laser heating effects. Here, we observed the dynamic redshift and broadening of zero phonon line of silicon-vacancy (SiV−) centers at 4 K. Utilizing the intrinsic temperature response of the fine structure spectra of SiV− as a probe, we confirmed that laser heating effect appears and the temperature rising results from high defect concentration. By simulating the thermal diffusion process, we have estimated the thermal conductivity of around 1 W/(m K), which is a two-order magnitude lower than that of single-crystal diamond. Our results provide a feasible scheme for all-optical non-contact temperature sensing and help to solve the problem of accurate measurement of thermal conductivity at cryogenic temperatures.