Thermal Stimulation Research Articles

Human Brain Organoids Model Abnormal Prenatal Neural Development Induced by Thermal Stimulation.

The developing human foetal brain is sensitive to thermal stimulation during pregnancy. However, the mechanisms by which heat exposure affects human foetal brain development remain unclear, largely due to the lack of appropriate research models for studying thermal stimulation. To address this, we have developed a periodic heating model based on brain organoids derived from human pluripotent stem cells. The model recapitulated neurodevelopmental disruptions under prenatal heat exposure at the early stages, providing a paradigm for studying the altered neurodevelopment under environmental stimulation. Our study found that periodic heat exposure led to decreased size and impaired neural tube development in the brain organoids. Bulk RNA-seq analysis revealed that the abnormal WNT signalling pathway and the reduction of G2/M progenitor cells might be involved in heat stimulation. Further investigation revealed increased neural differentiation and decreased proliferation under heat stimulation, indicating that periodic heat exposure might lead to abnormal brain development by altering key developmental processes. Hence, our model of periodically heating brain organoids provides a platform for modelling the effects of maternal fever on foetal brain development and could be extended to applications in neurodevelopmental disorders intervention.

The psychophysical assessments of tactile, temperature and electrical perception for implants with metal prosthetic surfaces.

The tactile function and thermal perception are two primary functions of oral structures. Implants without periodontal ligament and pulp might fail to sense the tactile and temperature change. This study aimed to investigate implants' tactile, thermal, and electrical perception by detailed psychophysical assessments. A total of forty-eight patients with single implant restoration were recruited. Mechanical (5 intensities), cold (4 temperatures), and electrical stimulation were respectively applied to implants and natural teeth, and the psychophysical results were recorded with a visual analog scale (VAS) and compared between implants and natural teeth. For tactile perception, at low and medium forces, implants were significantly poorer than natural teeth (P<0.01), but at the largest force, there were no significant differences (P >0.05). Regarding thermal perception, thermal changes on implants could be detected, although the signals were weaker when compared to natural teeth (P<0.01). Implants were less sensitive to electrical stimulation than natural teeth (P<0.01). Even though there is no periodontium and pulp, dental implants could perceive the mechanical, thermal, and electrical stimulation weakly.

Advancements and Future Prospects in the Hydraulic Fracturing of Geothermal Reservoirs

Reservoir reconstruction is a critical challenge in many significant underground energy projects, such as enhanced geothermal systems, oil shale extraction, and shale gas development. Effectively reconstructing geothermal reservoirs can significantly enhance the exploitation and production capacity of geothermal resources. However, this process requires stringent technical standards and varies with different geological conditions across regions, necessitating tailored reconstruction strategies. This review offers a comprehensive examination of hydraulic fracturing within geothermal reservoirs, covering the geological and physical characteristics inherent to these systems, the effects of injection methods and thermal stimulation on hydraulic fracturing processes, and the assessment and optimization of transformation effects, as well as environmental implications and risk management considerations. We explore the influence of various injection modes on hydraulic fracturing dynamics. Moreover, we compare the differences between hydraulic fracture propagation with and without thermal effects. Additionally, we summarize optimization strategies for reservoir reconstruction. Finally, we discuss several challenges and potential future directions for development, offering insights into possible advancements. This review is of substantial significance for both research and commercial applications related to hydraulic fracturing in geothermal reservoirs.

Advanced Thermoactive Nanomaterials for Thermomedical Tissue Regeneration: Opportunities and Challenges.

Nanomaterials usually possess remarkable properties, including excellent biocompatibility, unique physical and chemical characteristics, and bionic attributes, which make them highly promising for applications in tissue regeneration. Thermal therapy has emerged as a versatile approach for wound healing, nerve repair, bone regeneration, tumor therapy, and antibacterial tissue regeneration. By combining nanomaterials with thermal therapy, multifunctional nanomaterials with thermogenic effects and tissue regeneration capabilities can be engineered to achieve enhanced therapeutic outcomes. This study provides a comprehensive review of the effects of thermal stimulation on cellular and tissue regeneration. Furthermore, it highlights the applications of photothermal, magnetothermal, and electrothermal nanomaterials, and thermally responsive drug delivery systems in tissue engineering. In Addition, the bioactivities and biocompatibilities of several representative thermal nanomaterials are discussed. Finally, the challenges facing thermal nanomaterials are outlined, and future prospects in the field are presented with the aim of offering new opportunities and avenues for the utilization of thermal nanomaterials in tissue regeneration.

Simulation of peak properties in thermoluminescence dosimeters with the potential stimulation of all electron traps

In thermoluminescence (TL) models, the competition between energy levels for electron trapping is a direct consequence of conduction band mediation in electron transport. From a theoretical perspective, these competitive effects are considered responsible for many TL phenomena. Furthermore, while they are easily detectable in simulation studies, there are no clear and reliable criteria for their experimental verification. In the present work, it is suggested that in certain materials with narrow band gap energies, existing electron traps can be accessed by thermal stimulation up to 500 °C. It is possible to predict properties through simulation that can then be verified experimentally. The simulation is applied to a complex TL glow curve consisting of four electron trapping levels and one luminescence center. With the appropriate selection of simulation parameter values, the competition is limited solely to electron transport, rather than to significant differences in parameter values. The simulation indicated that the last peak serves as the primary competitor. Furthermore, the shape of the TL glow curve depends on the strength of the competition. When the competitor is strong, the lower temperature peaks behave as first-order peaks, and the shape of the glow curve remains stable as a function of dose. The last peak, which acts as the final competitor, exhibits behavior similar to that of the peak derived from the one trap, one recombination (OTOR) model. This OTOR-like behavior provides an excellent experimental test for the simulation results and, consequently, for the model used. The validity of the simulation was assessed by comparing the input values of kinetic parameters with the output values obtained from computerized glow curve deconvolution (CGCD) analysis for each TL glow curve.

The Effectiveness of Thermal Stimulation Plus Conventional Therapy for Functional Recovery After Stroke: A Systematic Review and Meta-Analysis.

Background: Motor impairments limit the functional abilities of patients after stroke; it is important to identify low-cost rehabilitation avenues. The aim of this study is to determine the effectiveness of thermal stimulation in addition to conventional therapy for functional recovery in post-stroke patients. Methods: An electronic search was performed in the MEDLINE, Scopus, Web of Science, EMBASE, CINAHL, SPORTDiscus, Epistemonikos, LILACS, and PEDro databases. The eligibility criterion was randomized clinical trials that analyzed the clinical effects of thermal stimulation plus conventional therapy. Two authors independently performed the search, study selection, data extraction, and risk of bias assessment. Results: Eight studies met the eligibility criteria, and six studies were included in the quantitative synthesis. For thermal stimulation plus conventional therapy versus conventional therapy alone, the mean difference (MD) for function was 6.92 points (95% CI = 4.36-9.48; p < 0.01), for motor function was 6.31 points (95% CI = 5.18-7.44; p < 0.01), for balance was 4.41 points (95% CI = -2.59-11.4; p = 0.22), and for walking was 1.01 points (95% CI = 0.33-1.69; p < 0.01). For noxious thermal stimulation versus innocuous thermal stimulation, the MD for activities of daily living was 1.19 points (95% CI = -0.46-2.84; p = 0.16). Conclusions: In the short term, adding thermal stimulation to conventional therapy showed statistically significant differences in functional recovery in post-stroke patients. The quality of evidence was high to very low according to GRADE rating. The studies included varied in the frequency and dosage of thermal stimulation, which may affect the consistency and generalizability of the results. A larger quantity and a better quality of clinical studies are needed to confirm our findings. PROSPERO registration: CRD42023423207.

Displaying Tactile Sensation by SMA-Driven Vibration and Controlled Temperature for Cutaneous Sensation Assessment

In this paper, we propose a novel tactile display that can present vibration patterns and thermal stimuli simultaneously. The vibration actuator employs a shape memory alloy (SMA) wire to generate micro-vibration with a frequency control of up to 300 Hz. The micro-vibration is conducted to a tactile pin for amplifying the vibration, to be sufficiently recognized by a user. A thermal stimulation unit, on the other hand, consists of four Peltier elements with heatsinks for heat radiation. Four vibration actuators and a thermal unit are arranged in a flat plane with a size of 20 mm × 20 mm, on which a user places the tip of an index finger to feel the presented vibratory stimuli under different temperature conditions. We conducted an experiment by employing nine subjects to evaluate the performance of the proposed tactile display and also to investigate the effects of temperature on recognizing tactile sensation. The results demonstrated that the proposed device was feasible for the quantitative diagnosis of tactile sensation. In addition, we verified that the sensitivity of tactile sensation decreased with colder stimuli.

High-temperature stimulation enhances polyhydroxyalkanoates accumulation in thermophile Aeribacillus pallidus BK1

Polyhydroxyalkanoates (PHAs) are intracellular storage polymers that enhance bacterial resistance in environments. While the role of PHAs regulation in thermophiles under high-temperature stimulation is understudied, this work investigates Aeribacillus pallidus BK1, a thermophile with heat resistance up to 155 °C. Our results showed that A. pallidus’s PHAs yield was 1.45 g/L. After 90 °C and 121 °C stimulations, the PHAs yield doubled to 3.33 g/L. The PHAs ratios increased from 35.63 % (60 °C) to 75.46 % (90 °C) and 77.15 % (121 °C). RNA-seq analysis revealed a common strategy of activating glucose transporters to enhance glucose uptake at both temperatures. At 90 °C, A. pallidus BK1 prioritized PHAs accumulation over the TCA cycle. At 121 °C, PHAs production was further enhanced by upregulating monomer polymerization and downregulating acetyl-CoA carboxylase expression. These findings offered valuable insights into the high-temperature defense mechanisms of thermophiles and suggested that A. pallidus BK1 holds promise as a bio-production platform for PHAs production under thermal stimulation.

Photoelectric Interaction and Photochromic Mechanism of K0.5Na0.5NbO3 Ceramics.

Rare-earth materials are widely used in the optical field due to their rich energy-level structures, and if endowed with photoelectric response characteristics, they are expected to be applied to photoelectric multifunctional devices. In this paper, Ho3+- and Yb3+-codoped K0.5Na0.5NbO3 (KNN) ferroelectric ceramics are synthesized, and the up-conversion and down-conversion luminescence intensity as well as the decay degree after photochromism can be controlled by the content of Yb3+. Strong green luminescence visible to the naked eye is realized, and the maximum luminescence decay is more than 50%. 2 s of color change fully indicates that the ceramic has the characteristics of fast response photochromic, under the most efficient wavelength of 405 nm by changing the irradiation wavelength. By incorporating data from thermal and electrical stimulation experiments, a comprehensive photochromic mechanism diagram is constructed, where the photochromic properties are predominantly governed by defects. It is believed that this work will provide a theoretical basis for the design of high-performance photochromic ceramics.

Hydrogen-Bonded Supramolecular Network Enabled Gentle Reprogramming of Liquid Crystal Elastomer toward Evolutionary Robot.

In nature, many organisms augment chances of survival by reprogramming their structures to evolving environment, among which sea squirts being a prime example. Such reprogramming has been demonstrated in liquid crystal elastomer (LCE) actuator assembled with heat assistance. However, the required temperature being higher than the actuation temperature limits its application. Here, we reported a hydrogen-bonded supramolecular network LCE to construct soft modular and reprogrammable actuator by assembling with a gentle heat treatment. Leveraging the Michael addition reaction, we introduced hydrogen bonding to the LCE matrix with functionalized pyridine monomers. Experimental and molecular dynamics modeling proved the efficient dynamic hydrogen bond exchange at 60 °C, significantly lower than the actuating temperature of the LCE. This gave rise to the reversible and robust adhesion of the same collection of LCE modules capable of being built into different bilayers and performing various morphing upon a short thermal stimulation. Therefore, we demonstrated that these comparatively weak cross-links enabled reconfiguration of the LCE actuator. With the developed hydrogen-bonding LCEs, we built proof-of-concept modular reprogrammable robot, performing crawling, sailing, and microcircuit repair tasks. This bioinspired and efficient method for evolutionary LCE robot offers a viable path for further development of intelligent actuators sustainable in complex environments.

Hydrogen‐Bonded Supramolecular Network Enabled Gentle Reprogramming of Liquid Crystal Elastomer toward Evolutionary Robot

AbstractIn nature, many organisms augment chances of survival by reprogramming their structures to evolving environment, among which sea squirts being a prime example. Such reprogramming has been demonstrated in liquid crystal elastomer (LCE) actuator assembled with heat assistance. However, the required temperature being higher than the actuation temperature limits its application. Here, we reported a hydrogen‐bonded supramolecular network LCE to construct soft modular and reprogrammable actuator by assembling with a gentle heat treatment. Leveraging the Michael addition reaction, we introduced hydrogen bonding to the LCE matrix with functionalized pyridine monomers. Experimental and molecular dynamics modeling proved the efficient dynamic hydrogen bond exchange at 60 °C, significantly lower than the actuating temperature of the LCE. This gave rise to the reversible and robust adhesion of the same collection of LCE modules capable of being built into different bilayers and performing various morphing upon a short thermal stimulation. Therefore, we demonstrated that these comparatively weak cross‐links enabled reconfiguration of the LCE actuator. With the developed hydrogen‐bonding LCEs, we built proof‐of‐concept modular reprogrammable robot, performing crawling, sailing, and microcircuit repair tasks. This bioinspired and efficient method for evolutionary LCE robot offers a viable path for further development of intelligent actuators sustainable in complex environments.

Solid-State Reversible Phase Transition and Photoluminescence Properties of Organic-Inorganic Hybrid Halide: (BTPA)2MnBr4.

Multifunctional materials have long been a popular research area, with organic-inorganic hybrids frequently utilized due to their diverse properties and versatile assembly techniques. In this context, a novel Mn-based organic-inorganic hybrid compound (BTPA)2MnBr4(1) was prepared, with strong green photoluminescence, phase transition under thermal stimulation, and two reversible dielectric-state switches. This compound exhibits strong green photoluminescence under ultraviolet excitation, boasting a quantum yield of 44.36%. Furthermore, it demonstrates a reversible ferroelastic phase transition at 358/348 K. The integration of temperature and photosensitivity in compound 1 opens up new avenues for the development and exploration of a broader spectrum of multifunctional phase transition materials.

Stimuli-responsive hydrogel microspheres encapsulated with tumor-cell-derived microparticles for malignant ascites treatment

Tumor-cell-derived microparticles (TMPs) have been recognized as chemotherapeutic drug carriers and immunomodulators for anti-tumor therapy. Research in the clinical application of TMPs has been devoted to developing an effective delivery formulation that could enhance their therapeutic effects. Here, we propose thermal-responsive agarose hydrogel microspheres (MTX-TMPs@MSs) with encapsulation of Methotrexate (MTX)-packaging TMPs (MTX-TMPs) and black phosphorus quantum dots (BPQDs) by microfluidic technology for synergistic treatment of malignant ascites. The laden MTX-TMPs, separated from apoptotic tumor cells, could target tumor cells for the delivery of chemotherapy drugs and modulate the tumor immune microenvironment. Under near-infrared (NIR) induced thermal stimulation, MTX-TMPs could be controllably released from the low-melting-point agarose matrix hydrogel microspheres for chemotherapy (CHT) and immunotherapy (IMT). In addition, benefiting from photothermal therapy (PTT)-induced tumor immunogenic death, the anti-tumor immune response triggered by MTX-TMPs was further enhanced. Based on these features, the MTX-TMPs@MSs could remarkably eliminate tumor cells in vitro and obviously suppress tumor growth in vivo through synergistic PTT, CHT, and IMT. Therefore, it is envisaged that this TMPs-integrated microcarrier will have promising applications in clinical tumor therapy. Statement of SignificancePrimary liver cancer ranks third among the causes of cancer deaths globally, with hepatocellular carcinoma (HCC) being the most common type. In particular, patients with advanced HCC accompanied by malignant ascites, a common complication, indicate tumor metastasis and a poor prognosis. In this paper, we developed stimuli-responsive hydrogel microspheres from microfluidics for the delivery of methotrexate (MTX)-loaded tumor-cell-derived microparticles (MTX-TMPs) for synergistic chemotherapy, photothermal therapy, and immunotherapy. The release of MTX-TMPs from hydrogel microspheres could be on-demand controlled through BPQDs-mediated photothermal stimulus. On the other hand, BPQDs-mediated mild hyperthermia cooperatesss with MTX-TMPs-induced chemotherapy could participate in remodeling the tumor immunosuppressive microenvironment. Thus, the prepared microcarrier system holds great promise for tumor therapy.

Light‐ and Temperature‐Controlled Hybridization, Chiral Induction and Handedness of Helical Foldamers

AbstractHelical foldamers have attracted much attention over the last decades given their resemblance to certain biomacromolecules and their potential in domains as different as pharmaceutics, catalysis and photonics. Various research groups have successfully controlled the right‐ or left‐ handedness of these oligomers by introducing stereogenic centers through covalent or non‐covalent chemistry. However, developing helical structures whose handedness can be reversibly switched remains a major challenge for chemists. To date, such an achievement has been reported with light‐responsive single‐stranded foldamers only. Herein, we demonstrate that grafting a unidirectional motor onto foldamer strands constitutes a relevant strategy to i) control the single or double helical state of a foldamer, ii) switch on the chiral induction process from the motor to the helical strands and iii) select the handedness of double helical structures through photochemical and thermal stimulations.

Light- and Temperature-Controlled Hybridization, Chiral Induction and Handedness of Helical Foldamers.

Helical foldamers have attracted much attention over the last decades given their resemblance to certain biomacromolecules and their potential in domains as different as pharmaceutics, catalysis and photonics. Various research groups have successfully controlled the right- or left- handedness of these oligomers by introducing stereogenic centers through covalent or non-covalent chemistry. However, developing helical structures whose handedness can be reversibly switched remains a major challenge for chemists. To date, such an achievement has been reported with light-responsive single-stranded foldamers only. Herein, we demonstrate that grafting a unidirectional motor onto foldamer strands constitutes a relevant strategy to i) control the single or double helical state of a foldamer, ii) switch on the chiral induction process from the motor to the helical strands and iii) select the handedness of double helical structures through photochemical and thermal stimulations.

Photo-thermal and temperature-regulated sodium alginate-g-mPEG/carbon nanotube hybrid fibers with improved tensile strength

Despite the remarkable potential of phase change fibers for energy storage, their practical deployment has been hindered by two crucial challenges: inadequate external thermal stimulation to induce phase transition and leakage of the phase-change material. In this study, we successfully incorporated carbon nanotubes (CNTs) into a solution of sodium alginate grafted polyethylene glycol monomethyl ether (SA-g-mPEG) and utilized wet spinning processing to fabricate CNTs/SA-g-mPEG hybrid fibers with enhanced photo-thermal conversion and robust solid-solid phase change capabilities. Upon exposure to sunlight for merely 60 s, the hybrid fibers achieved a remarkable peak temperature of 40 °C. Upon cessation of sunlight exposure, these fibers demonstrated a gradual release of thermal energy, thereby underlining their exceptional photothermal conversion and temperature regulation capabilities. Furthermore, DSC analysis revealed that, at an optimal grafting ratio of 36.6 %, the hybrid fibers exhibited ΔHc and ΔHm values of 48.23 J/g and 50.83 J/g, respectively. Notably, hybrid fibers with a grafting ratio of 20.2 % demonstrated substantial enhancements in tensile properties, achieving a maximum breaking strength of approximately 2.02 cN/dtex—an impressive 11.3 % increase compared to SA-g-mPEG composite fibers. Our findings suggest that CNTs/SA-g-mPEG hybrid fibers hold immense promise for applications in body heat storage, fabric temperature regulation, and related fields.

A Study on the Physiological Diversity of Hand Bathing under Different Conditions

Achieving the best outcomes and ensuring patients are as comfortable as possible are crucial goals for healthcare professionals. Hospital stress has been linked to worsening patient outcomes and so it is important to implement methods for keeping patients calm. Targeting the autonomic nervous system through hand bathing could provide answers. Associate Professor Hajime Nakano and his collaborators at the Faculty of Nursing, Josai International University, Japan, used precise tools to measure the heart rates of patients bathing their hands in waterbaths maintained at carefully controlled temperatures. The researchers used a probe to non-invasively measure brain activation and found that hand bathing decreased sympathetic nervous system activity, increased parasympathetic nervous system activity and produced feelings of relaxation. Nakano and the team conducted another study in which they activated the sympathetic nervous system in volunteers with mental arithmetic and found that hand bathing significantly suppressed the activation. This led them to posit that thermal stimulation has the potential to impact the stress responses in patients and their motivation in a bidirectional manner, which indicated significant possibilities for clinical applications. The researchers are keen to explore how altering the temperature of the hand bath can positively impact patients and an optimum temperature be selected. The team wants to ensure that interventions are tailored to the unique needs of patients and, as such, observed responses under different conditions and collected vast data that has enabled them to consider a research design that accommodated individual differences.

Pyramid-like magnetic carbon composites device toward tunable and adaptive radar-visible compatible properties

Equipped with intelligent adjustable electromagnetic-visible light compatibility characteristics is of significant importance in military stealth fields. In this work, a tunable microwave absorption and visible light change metamaterial based on polylactic acid (PLA) thermal stimulation was fabricated using 4D printing technology with hydroxylated carbon nanotubes (CNTOH) and carbonyl iron powder (CIP) as active ingredients. The printing filament was synthesized, which exhibited excellent absorption performance with a bandwidth of 5.83 GHz and sufficient shape recovery ability. On this basis, a temperature-dominated shape memory variation cone device was also manufactured and the visible light color-changing coating was sprayed. The microwave absorption performance is adjusted according to the petal angle, achieving a bandwidth variation of 5.9–9.8 GHz. This work confirms the potential exploratory value of the designed shape memory polymer in the field of microwave absorption, and provides unlimited possibilities for designing intelligent controlled stealth materials.

Exosomal circPTPRK promotes angiogenesis after radiofrequency ablation in hepatocellular carcinoma.

Radiofrequency ablation (RFA) is an effective treatment for hepatocellular carcinoma (HCC), but the recurrence rate remains high due to angiogenesis in residual cancer cells. We used thermal stimulation to simulate the post-RFA microenvironment. The expression profile of circRNAs between normal control HCC cell-derived exosomes and exosomes after heat stimulation were analyzed by RNA sequencing. Quantitative real-time PCR was applied to evaluate the expression of circPTPRK in exosomes and human umbilical vein endothelial cells (HUVECs). Then, the functions of heat-stimulated HCC cell-derived exosomes and exosomal circPTPRK on HUVECs were unveiled. Transcriptome sequencing was utilized to determine targeted genes of circPTPRK. Heat-stimulated HCC cell-derived exosomes augmented cell proliferation, migration, and angiogenesis of HUVECs. In total, 229 differentially expressed circRNAs were obtained, including 211 upregulated circRNAs and 18 downregulated circRNAs in heat-stimulated HCC cell-derived exosomes. The expression of circPTPRK was remarkably increased in heat-stimulated HCC cell-derived exosomes and the HUVECs incubated with them. Heat-stimulated HCC cell-derived exosomes with circPTPRK knockdown significantly inhibited cell proliferation, migration, and angiogenesis of HUVECs. Mechanistic studies indicated that PLA2G4E is a downstream target of circPTPRK, and PLA2G4E overexpression reversed the inhibitory effect of circPTPRK knockdown on HUVEC angiogenesis. Our results indicated that exosomal circPTPRK activated HUVEC angiogenesis by upregulating PLA2G4E expression.

A molecular-chemistry-manipulation strategy toward functional lignin-based porous carbon nanospheres with tunable-pore structure

Porous carbon nanospheres derived from biomass materials have inspired numerous interests in various areas. Nevertheless, their fabrications mainly depend on template-assisted or chemical activation routes. Here, a molecular-chemistry-manipulation strategy was proposed innovatively by taking advantage of the heterogeneous self-condensation characters of lignin molecules under thermal stimulation, opening a practical and versatile synthetic platform for the construction of lignin-based hierarchical porous carbon nanospheres (LHPCS). We can manipulate the condensed kinetics by tuning the environmental variables and forming designated nanospheres with inhomogeneous molecular chemistry. This intraparticle difference could provide a possibility to tune its refined structure for synthesizing hierarchical porous carbon nanospheres. Such LHPCS behaved the specific surface area of 962 m2 g−1 and pore volume of 0.76 cm3 g−1, as well as regulable pore ratios (15.5–22.9 % of macropore, 12.7–37 % for mesopore and 45–68.9 % for micropore). Besides, the monodisperse spherical morphology with hierarchical interleaved channels affords them excellent performance in optical management and energy storage, including pore-determined photothermal properties, extremely low reflectance of ca. 1.9 %, stable multi-angles specular reflectance, and anti-self-discharge induced by charge rearrangement. Our proposed molecular chemistry strategy provides an alternative pathway for constructing gradient and adjustable pore structures.