Tissue Heating Research Articles

Safety of non-invasive brain stimulation in patients with implants: a computational risk assessment.

Non-invasive brain stimulation (NIBS) methodologies, such as transcranial electric (tES) are increasingly employed for therapeutic, diagnostic, or research purposes. The concurrent presence of active/passive implants can pose safety risks, affect the NIBS delivery, or generate confounding signals. A systematic investigation is required to understand the interaction mechanisms, quantify exposure, assess risks, and establish guidance for NIBS applications. We used measurements, simplified generic, and detailed anatomical modeling to: (i) systematically analyze exposure conditions with passive and active implants, considering local field enhancement, exposure dosimetry, tissue heating and neuromodulation, capacitive lead current injection, low-impedance pathways between electrode contacts, and insulation damage; (ii) identify risk metrics and efficient prediction strategies; (iii) quantify these metrics in relevant exposure cases and (iv) identify worst case conditions. Various aspects including implant design, positioning, scar tissue formation, anisotropy, and frequency were investigated. At typical tES frequencies, local enhancement of dosimetric exposure quantities can reach up to one order of magnitude for deep brain stimulation (DBS) and stereoelectroencephalography implants (more for elongated passive implants), potentially resulting in unwanted neuromodulation that can confound results but is still 2-3 orders of magnitude lower than active DBS. Under worst-case conditions, capacitive current injection in the active implants' lead can produce local exposures of similar magnitude as the passive field enhancement, while capacitive pathways between contacts are negligible. Above 10 kHz, applied current magnitudes increase, necessitating consideration of tissue heating. Furthermore, capacitive effects become more prominent, leading to current injection that can reach DBS-like levels. Adverse effects from abandoned/damaged leads in direct electrode vicinity cannot be excluded. Safety related concerns of tES application in the presence of implants are systematically identified and explored, resulting in specific and quantitative guidance and establishing basis for safety standards. Furthermore,several methods for reducing risks are suggested while acknowledging the limitations(see Sec. 4.5).

A pearl millet plasma membrane protein, PgPM19, facilitates seed germination through the negative regulation of abscisic acid-associated genes under salinity stress in Arabidopsis thaliana.

The pearl millet gene PgPM19 inhibits seed dormancy by negatively regulating the ABA biosynthesis and ABA signaling pathways in response to salinity stress in Arabidopsis. Abscisic acid (ABA) plays a pivotal role in orchestrating plant stress responses and development. However, how the ABA signal is transmitted in response to stresses remains primarily uncertain, particularly in monocotyledonous plants. In this study, PgPM19, a gene whose expression is induced by drought, salinity, heat, and ABA in both leaf and root tissues, was isolated from pearl millet. The expression of PgPM19 in yeast cells did not influence their growth when subjected to mannitol, sorbitol, or NaCl stress. However, Arabidopsis plants overexpressing PgPM19 (PgPM19_OE plants) exhibited increased germination rates, greater fresh weights and longer roots under salinity stress during germination, compared to wild-type (WT) plants. Conversely, the pm19L1 (SALK_075435) mutant, featuring a transfer DNA insertion in a closely related PgPM19 homolog (AT1G04560) in Arabidopsis, demonstrated reduced germination rates and smaller fresh weights under salinity-stressed condition than did WT and PgPM19_OE plants. A pivotal ABA biosynthesis gene, NCED3, ABA signaling pathway genes, such as PYL6 and SnRK2.7, alongside downstream ABI genes and stress-responsive genes RAB28 and RD29, were downregulated in PgPM19_OE plants, as evidenced by both transcriptome analysis and quantitative reverse transcription-PCR. These findings raise the possibility that PgPM19 is involved in regulating seed germination by mediating ABA biosynthesis and signaling pathway in response to salinity stress in Arabidopsis. This study contributes to a better understanding of PgPM19 in response to salinity stress and establishes a foundation for unraveling the crosstalk of stress responses and ABA in Arabidopsis and other plant species.

Inhibition of LPS-induced inflammatory response in RAW264.7 cells by natural Chlorogenic acid isomers involved with AKR1B1 inhibition

Inflammation is the physiological response of the immune system to injury or infection, typically manifested by local tissue congestion, swelling, heat, and pain. Prolonged or excessive inflammation can lead to tissue damage and the development of many diseases. The anti-inflammatory effects of natural ingredients have been extensively researched and confirmed. This study investigated the effects of Chlorogenic acid (CGA) isomers —— 3-Caffeolyquninic acid (3-CQA), 4-Caffeolyquninic acid (4-CQA), and 5-Caffeolyquninic acid (5-CQA) —— on the inflammatory response and oxidative stress reaction induced by LPS in RAW264.7 cells. Overall, 3-CQA exhibited the most significant reduction in levels of TNF-α, IL-6, NO, and ROS. 4-CQA showed superior inhibition of TNF-α compared to 5-CQA (p < 0.05), while no significant difference in other parameters. We further used DARTS and CETSA to demonstrate that CGA isomers have stable affinity with AKR1B1. As a positive control, the AKR1B1 antagonist epalrestat exhibited similar effects to the CGA isomers. 3-CQA having the smallest half-inhibitory concentration (IC50) for AKR1B1, while 4-CQA and 5-CQA have similar values. AutoDock simulations of the docking conformations revealed minimal differences in the average binding energies of the CGA isomers. The main differences were that VAL47 formed a hydrogen bond with 3-CQA, whereas GLN49 formed hydrogen bonds with 4-CQA and 5-CQA. Additionally, the number of hydrophobic bonds involving PHE122 and LEU300 varies. Our conclusion is that differences in non-covalent interactions result in the varying inhibitory abilities of CGA isomers on AKR1B1, which further affect the anti-inflammatory and antioxidant effects of CGA isomers.

Development of a murine laser interstitial thermotherapy system.

The objective of this study was to develop a murine system for the delivery of laser interstitial thermotherapy (LITT) with probe-based thermometry as a model for human glioblastoma treatment to investigate thermal diffusion in heterogeneous brain tissue. First, the tissue heating properties were characterized using a diode-pumped solid-state near-infrared laser in a homogeneous tissue model. The laser was adapted for use with a repurposed stereotactic surgery frame utilizing a micro laser probe and Hamilton syringe. The authors designed and manufactured a stereotactic frame attachment to work as a temperature probe stabilizer. Application of this novel design was used as a precise method for real-time thermometry at known distances from the thermal ablative center mass during murine LITT studies. Temperature measurements were achieved during LITT that verified the direct thermometry capability of the system without the need for MR-based thermal monitoring. Application of multiple stereotactic design iterations led to an accurately reproducible surgical laser ablation procedure. Histological staining confirmed precise thermal ablation and controllable lesion size based on time and temperature control. Treatment of a syngeneic intracranial glioma model highly resistant to conventional therapy resulted in a modest survival benefit. The authors have successfully developed a murine model system of LITT with direct in situ thermometry for investigation into the effects of thermal ablation and combinatorial treatments in murine brain tumor models.

Exploring the Potential of Tunnel Field-Effect Transistors in Biomedical Devices: A Comprehensive Survey

Implantable medical devices have revolutionized healthcare by providing continuous monitoring and therapeutic interventions within the human body. The overall performance of these devices is heavily dependent on the effectiveness and efficiency of integrated electronic components, such as transistors. This survey explores the growing utilization of Tunnel Field-Effect Transistors (TFETs) in implantable devices, shedding light on their advantages and challenges in this specific application domain. TFETs, characterized by their unique tunnelling mechanism, offer several advantages that make them well suited for implantable devices. Their low-power consumption, reduced leakage current, and improved subthreshold swing make them ideal for energy-efficient, long-lasting operation within the constrained power budgets of implantable devices. Furthermore, TFETs exhibit excellent performance at low supply voltages, ensuring minimal tissue damage and heat generation. This survey also addresses the challenges associated with TFETs in implantable devices, including fabrication complexities, variability, and compatibility with existing technologies. It highlights recent advancements in TFET technology that address these concerns, such as improved material choices and manufacturing techniques. As technology continues to advance, TFETs are poised to play a pivotal role in improving the overall efficiency and reliability of life-saving technologies and medical devices. Overall, this survey provides valuable insights into the current state and future prospects of TFETs in implantable devices, guiding researchers and engineers in harnessing their potential for the benefit of healthcare and patient well-being.

Utilizing Carbon Nanomaterials for Enhanced Photothermal Therapy in Breast Cancer Treatment

Breast cancer is the most often diagnosed cancer in women and the second largest cause of cancer mortality worldwide. Photothermal therapy (PTT) has emerged as a viable cancer treatment that uses near-infrared (NIR) light-absorbing chemicals to selectively heat and destroy tumor cells while sparing healthy tissue. PTT has advantages such as high specificity, little invasiveness, and efficient tumor ablation. Recent advances include developing imageable photothermal agents to aid in therapy planning. This review focuses on the function of carbon nanoparticles in PTT, investigating their processes and advantages and analysing in vitro and in vivo investigations. Carbon nanomaterials like carbon nanotubes (CNTs) and graphene have a large surface area, great electrical conductivity, and biocompatibility, making them ideal for PTT. Carbon nanomaterials absorb NIR light, enabling deep tissue penetration and targeted heating of tumor tissues, resulting in necrosis and apoptosis. Carbon nanomaterials also increase tumor vascular permeability, which promotes chemotherapeutic drug accumulation and improves treatment results. Repurposing carbon nanomaterials for increased PTT is a potential method because of its capacity to target various pathways, select cytotoxicity against cancer cells, and synergistic effects with other anticancer drugs.

Osteogenic Potential and Long-Term Enzymatic Biodegradation of PHB-based Scaffolds with Composite Magnetic Nanofillers in a Magnetic Field.

Millions of people worldwide suffer from musculoskeletal damage, thus using the largest proportion of rehabilitation services. The limited self-regenerative capacity of bone and cartilage tissues necessitates the development of functional biomaterials. Magnetoactive materials are a promising solution due to clinical safety and deep tissue penetration of magnetic fields (MFs) without attenuation and tissue heating. Herein, electrospun microfibrous scaffolds were developed based on piezoelectric poly(3-hydroxybutyrate) (PHB) and composite magnetic nanofillers [magnetite with graphene oxide (GO) or reduced GO]. The scaffolds' morphology, structure, mechanical properties, surface potential, and piezoelectric response were systematically investigated. Furthermore, a complex mechanism of enzymatic biodegradation of these scaffolds is proposed that involves (i) a release of polymer crystallites, (ii) crystallization of the amorphous phase, and (iii) dissolution of the amorphous phase. Incorporation of Fe3O4, Fe3O4-GO, or Fe3O4-rGO accelerated the biodegradation of PHB scaffolds owing to pores on the surface of composite fibers and the enlarged content of polymer amorphous phase in the composite scaffolds. Six-month biodegradation caused a reduction in surface potential (1.5-fold) and in a vertical piezoresponse (3.5-fold) of the Fe3O4-GO scaffold because of a decrease in the PHB β-phase content. In vitro assays in the absence of an MF showed a significantly more pronounced mesenchymal stem cell proliferation on composite magnetic scaffolds compared to the neat scaffold, whereas in an MF (68 mT, 0.67 Hz), cell proliferation was not statistically significantly different when all the studied scaffolds were compared. The PHB/Fe3O4-GO scaffold was implanted into femur bone defects in rats, resulting in successful bone repair after nonperiodic magnetic stimulation (200 mT, 0.04 Hz) owing to a synergetic influence of increased surface roughness, the presence of hydrophilic groups near the surface, and magnetoelectric and magnetomechanical effects of the material.

Feasibility and safety assessment of RF double applications in very high power and short duration ablation

BackgroundThe QDOT-MICRO catheter enables very high power and short duration (vHPSD) ablation. However, low first-pass isolation rates have been reported, possibly because of shallow lesion formation, necessitating deeper lesions to improve treatment outcomes. ObjectiveThis study aimed to confirm the safety and efficacy of double radiofrequency applications of vHPSD ablation in an in vivo beating swine heart model. MethodsEighteen swine were anesthetized and underwent vHPSD ablation using the QDOT-MICRO catheter at 90 W for 4 seconds, targeting a contact force of 10 g. Radiofrequency applications were performed as single application (SA) and double applications (DAs) with 4- to 8-second rest intervals. Lesion surface area and volume were measured postablation. ResultsA total of 337 atrial lesions and 74 ventricular lesions were created. Both 4- to 6-second DA and 7- to 8-second DA produced significantly larger and deeper lesions than did SA, with atrial surface lengths averaging 9.0 mm for 4- to 6-second DA, 9.2 mm for 7- to 8-second DA, and 8.0 mm for SA. Transmurality was observed at 100% for 4- to 6-second and 7- to 8-second DAs, while it was 94% for SA (P = .002). Ventricular lesion metrics followed similar trends. Except for 1 event of tiny char formation during 4-second DA in the ventricle, neither steam pops nor char formation was observed in either the atrium or the ventricle. ConclusionIn an in vivo swine heart model, DA with 4- to 6-second and 7- to 8-second intervals create deeper and wider lesions than does SA, suggesting its potential for clinical application in areas with thicker myocardial walls. However, DA with very short intervals may still pose a risk of excessive tissue heating.

Design of a Conformal Ablation System Based on Independent Control of Radiofrequency Electrode Arrays

This study aims to develop an independent control system for radiofrequency electrode arrays, intended for the conformal ablation of unwanted tissues. Unlike traditional single radiofrequency voltage applications, this study employs high-frequency transformer isolation and radiofrequency load matching technologies to divide the radiofrequency signal source into eight independent groups. Each group operates at the same phase and frequency but with different voltage values. Experimental results indicate that the designed system can independently output various combinations of radiofrequency signals. The actual output voltage has a relative error controlled within 6%, the frequency error is less than 0.5%, and the phase difference among the groups is less than 1°. In the biomimetic tissue heating experiments, it is found that by controlling the voltage of each electrode within the electrode array, ablation of different shapes can be achieved, and the ablation depth is positively correlated with the applied radiofrequency voltage.

Characterizing Temperature-Dependent Acoustic and Thermal Tissue Properties for High-Intensity Focused Ultrasound Computational Modeling

High-intensity focused ultrasound (HIFU) thermal therapies utilize concentrated sound waves to ablate diseased tissue at precise locations within the body. Computational simulations of HIFU can assist clinicians by predicting the death of target tissues, identifying sensitive healthy tissues that risk thermal damage, and optimizing acoustic power delivery to minimize treatment times and maximize treatment efficacy. Accurate simulations require accurate inputs, and many computational solvers neglect property changes induced by tissue heating during treatment. Additionally, temperature-dependent tissue property data in the literature are relatively scarce. This study presents methodology for characterizing temperature-dependent acoustic and thermal properties in ex vivo porcine muscle tissue. From 20 – 50 °C, speed of sound is found to increase from approximately 1580 – 1620 m/s. The acoustic attenuation coefficient increases for 20 – 50 °C from 0.09 – 0.24 Np/cm at 0.5 MHz and 0.16 – 0.37 Np/cm at 1.6 MHz. Thermal conductivity and thermal diffusivity increase from 0.52 – 0.55 W/m °C and 0.147 – 0.158 mm2/s, respectively, over 20 – 60 °C. Specific heat capacity increases from approximately 3500 – 3800 J/kg °C, over 20 – 80 °C. Each property is consistent with data found in the literature, extends the literature to a larger temperature range, and, for acoustic properties, extends to unique frequencies. Temperature-dependent predictive models are also developed for each of the five properties. This study’s property measurement methodologies can be used to characterize other biological tissues, and the predictive models developed herein will facilitate future efforts in temperature-dependent modeling and uncertainty quantification of HIFU thermal therapies.

Absolute Quantification of Glutathione Using Top-Hat Optics for IR-MALDESI Mass Spectrometry Imaging.

Infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) uses an infrared laser to desorb neutral biomolecules with postionization via ESI at atmospheric pressure. The Gaussian profile of the laser with conventional optics results in the heating of adjacent nonablated tissue due to the energy profile being circular. A diffractive optical element (DOE) was incorporated into the optical train to correct for this disadvantage. The DOE produces a top-hat beam profile and square ablation spots, which have uniform energy distributions. Although beneficial to mass spectrometry imaging (MSI), it is unknown how the DOE affects the ability to perform quantitative MSI (qMSI). In this work, we evaluate the performance of the DOE optical train against our conventional optics to define the potential advantages of the top-hat beam profile. Absolute quantification of glutathione (GSH) was achieved by normalizing the analyte of interest to homoglutathione (hGSH), spotting a dilution series of stable isotope labeled glutathione (SIL-GSH), and analyzing by IR-MALDESI MSI with either the conventional optical train or with the DOE incorporated. Statistical comparison indicates that there was no significant difference between the quantification of GSH by the two optical trains as evidenced by similar calibration curves. Results support that both optical trains can be used for qMSI without a change in the ability to carry out absolute quantification but providing the benefits of the top-hat optical train (i.e., flat energy profile and square ablation spots)-for future qMSI studies.

On fractional Pennes bio-heat equation using Legendre collocation method

In this paper, the distribution of heat in skin tissue during thermal treatment using the time-fractional Pennes model is studied. Temperature variations concerning several parameters such as derivative [Formula: see text] time, blood perfusion, and transmitted power are described using the Legendre collocation technique. The best feature of the proposed technique is the conversion of fractional-order differential equations into a set of algebraic systems and the ability to approximate both spatial and temporal coordinates with a single basis. The obtained results and comparison with an exact solution are illustrated.

Facemask vapor trapping, condensation, and thermoregulation

The widespread adoption of facemasks in various contexts has highlighted challenges associated with prolonged mask-wearing. Despite their effectiveness in preventing the spread of pathogens, issues such as discomfort, stuffiness, and fogging of eyeglasses can deter individuals from wearing masks consistently. Understanding the mechanisms of thermal and humidity regulation during facemask use is crucial for addressing these challenges. This study investigates the impact of face mask-wearing on facial thermoregulation and moisture accumulation, comparing conditions with and without masks. An integrated computational model was developed to consider respiratory flows, tissue heat generation, skin convective heat dissipation, the influence of inhaled cool air and exhaled warm air, and their interactions with the mask media. Model validation was conducted using complementary Schlieren imaging and transient temperature measurements. Results reveal significant increases in facial temperature with well-fitted masks and highlight the role of trapped moisture inside the mask. Thermo-humidity variations beneath the mask and condensations in the mask were quantified, providing insights into facemask-wearing thermoregulation. The effects of moist vs. dry air, steady vs. tidal breathing, and with vs. without buoyancy were quantitatively compared. These findings have implications for improving mask design and promoting adherence in diverse environmental settings. Addressing these discomfort-related challenges is crucial for enhancing mask adherence and ensuring adequate protection.

Asymptotic solution of electromagnetic heating of skin tissue with lateral heat conduction

We study the temperature evolution in the three-dimensional skin tissue exposed to an electromagnetic beam of millimeter wavelength. The skin absorption coefficient of the beam frequency determines how deep the electromagnetic energy penetrates into the skin tissue, which gives a sub-millimeter penetration depth for a 94 GHz wave. In contrast, in the lateral directions perpendicular to the depth, the beam size is usually much larger than the penetration depth. Based on this separation of length scales, we establish an asymptotic formulation in which each term has separable dependences on the depth coordinate and on the lateral coordinates. We solve it analytically to obtain a two-term asymptotic solution of the temperature distribution in the three-dimensional skin tissue. This closed-form analytical solution provides a practical and accurate way of predicting the temperature. When the beam size is moderately larger than the penetration depth (a ratio of 20), the effect of lateral heat conduction is well captured in the asymptotic solution with maximum error less than 0.0017 in the normalized temperature of magnitude well above 1.

Multifrequency Circuit Impedance Measurements may Improve Durable Ablation Lesion Assessment: Differentiating Cellular Destruction From Tissue Heating

Multifrequency Circuit Impedance Measurements may Improve Durable Ablation Lesion Assessment: Differentiating Cellular Destruction From Tissue Heating

Effects of monopolar pulsed-capacitive dielectric radiofrequency diathermy in patients with chronic low back pain: a randomised clinical trial

Monopolar capacitive diathermy is a physiotherapy technique that uses high-frequency currents to generate heat in deep tissues. This heat can have several therapeutic effects, especially in the treatment of chronic low back pain (CLBP), however, until now there is little evidence of this type of diathermy. The purpose was to evaluate the efficacy of a pulsed monopolar dielectric radiofrequency diathermy (PRF)-capacitive type versus simulated treatment on symptomatology of patients with CLBP. A single-blind randomised controlled trial was conducted. Sixty patients with CLBP were randomly assigned to a PRF-capacitive or a simulated treatment group. All participants received 3 sessions per week for 3 weeks. Disability, pain intensity, movement phobia, lumbar anteflexion, quality of life, and sleep quality were assessed at baseline, after treatment, and at two months. The application of 9 sessions of PRF-capacitive showed significant improvements compared to simulated therapy during the entire follow-up for disability (F = 26.99, p < 0.001), pain intensity (F = 0.550, p < 0.001), the quality of life components of physical function (F = 0.780, p < 0.001), social function (F = 0.780, p < 0.001) and mental health (F = 0.858, p = 0.003) and for sleep duration (F = 0.863, p = 0.004).

Disaggregation of canopy photosynthesis among tree species in a mixed broadleaf forest.

Carbon dioxide sequestration from the atmosphere is commonly assessed using the eddy covariance method. Its net flux signal can be decomposed into gross primary production and ecosystem respiration components, but these have seldom been tested against independent methods. In addition, eddy covariance lacks the ability to partition carbon sequestration among individual trees or species within mixed forests. Therefore, we compared gross primary production from eddy covariance versus an independent method based on sap flow and water-use efficiency, as measured by the tissue heat balance method and δ13C of phloem contents, respectively. The latter measurements were conducted on individual trees throughout a growing season in a mixed broadleaf forest dominated by three tree species, namely English oak, narrow-leaved ash and common hornbeam (Quercus robur L., Fraxinus angustifolia Vahl, and Carpinus betulus L., respectively). In this context, we applied an alternative ecophysiological method aimed at verifying the accuracy of a state-of-the-art eddy covariance system while also offering a solution to the partitioning problem. We observed strong agreement in the ecosystem gross primary production estimates (R2=0.56; P<0.0001), with correlation being especially high and nearly on the 1:1 line in the period before the end of July (R2=0.85; P<0.0001). After this period, the estimates of gross primary production began to diverge. Possible reasons for the divergence are discussed, focusing especially on phenology and the limitation of the isotopic data. English oak showed the highest per-tree daily photosynthetic rates among tree species, but the smaller, more abundant common hornbeam contributed most to the stand-level summation, especially early in the spring. These findings provide a rigorous test of the methods and the species-level photosynthesis offers avenues for enhancing forest management aimed at carbon sequestration.

Repeatability of image quality in very low-field MRI.

Very low-field MR has emerged as a promising complementary device to high-field MRI scanners, offering several advantages. One of the key benefits is that very low-field scanners are generally more portable and affordable to purchase and maintain, making them an attractive option for medical facilities looking to reduce costs. Very low-field MRI systems also have lower RF power deposition, making them safer and less likely to cause tissue heating or other safety concerns. They are also simpler to maintain, as they do not require cooling agents such as liquid helium. However, these portable MR scanners are impacted by temperature, lower magnetic field strength, and inhomogeneity, resulting in images with lower signal-to-noise ratio (SNR) and higher geometric distortions. It is essential to investigate and tabulate the variations in these parameters to establish bounds so that subsequent in vivo studies and deployment of these portable systems can be well informed. The aim of this work is to investigate the repeatability of image quality metrics such as SNR and geometrical distortion at 0.05 T over 10 days and three sessions per day. We acquired repeatability data over 10 days with three sessions per day. The measurements included temperature, humidity, transmit frequency, off-resonance maps, and 3D turbo spin echo (TSE) images of an in vitro phantom. This resulted in a protocol with 11 sequences. We also acquired a 3 T data set for reference. The image quality metrics included computing SNR and eccentricity (to assess geometrical distortion) to investigate the repeatability of 0.05 T image quality. The image reconstruction included drift correction, k-space filtering, and off-resonance correction. We computed the experimental parameters' coefficient of variation (CV) and the resulting image quality metrics to assess repeatability. We have explored the impact of electromagnetic interference (EMI) on image quality in very low-field MRI. The investigation involved varying both the distance and amplitude of the EMI-producing coil from the signal generator to analyze their effects on image quality. The range of temperature measured during the study was within 1.5 °C. The off-resonance maps acquired before and after the 3D TSE showed similar hotspots and were changed mainly by a global constant. The SNR measurements were highly repeatable across sessions and over the 10 days, quantified by a CV of 6.7%. The magnetic field inhomogeneity effects quantified by eccentricity showed a CV of 13.7%, but less than 5.1% in two of the three sessions over 10 days. The use of conjugate phase reconstruction mitigated geometrical distortion artifacts. Temperature and humidity did not significantly affect SNR or mean frequency drift within the ranges of these environmental factors investigated. The EMI experiment showed that as the amplitude increased the SNR decreased, and concurrently the root mean square of the background increased with a rise in EMI amplitude or a reduction in distance. We found that humidity and temperature in the range investigated did not impact SNR or frequency. Based on the CV values computed session-wise and for the overall study, our findings indicate high repeatability for SNR and magnetic field homogeneity.

In Vitro Study of Tumor-Homing Peptide-Modified Magnetic Nanoparticles for Magnetic Hyperthermia.

Cancer cells have higher heat sensitivity compared to normal cells; therefore, hyperthermia is a promising approach for cancer therapy because of its ability to selectively kill cancer cells by heating them. However, the specific and rapid heating of tumor tissues remains challenging. This study investigated the potential of magnetic nanoparticles (MNPs) modified with tumor-homing peptides (THPs), specifically PL1 and PL3, for tumor-specific magnetic hyperthermia therapy. The synthesis of THP-modified MNPs involved the attachment of PL1 and PL3 peptides to the surface of the MNPs, which facilitated enhanced tumor cell binding and internalization. Cell specificity studies revealed an increased uptake of PL1- and PL3-MNPs by tumor cells compared to unmodified MNPs, indicating their potential for targeted delivery. In vitro hyperthermia experiments demonstrated the efficacy of PL3-MNPs in inducing tumor cell death when exposed to an alternating magnetic field (AMF). Even without exposure to an AMF, an additional ferroptotic pathway was suggested to be mediated by the nanoparticles. Thus, this study suggests that THP-modified MNPs, particularly PL3-MNPs, hold promise as a targeted approach for tumor-specific magnetic hyperthermia therapy.

A wireless-power and data-transfer using inductive RF link and ASK modulation

This paper aims to present a novel trans-cutanaeous, wireless and an efficient radio frequency (RF) inductive power and data link (IPDL) based on amplitude shift key (ASK) - modulator with an efficient ‘Class-E’– RF ‘power amplifier’ that is applicable to implantable medical devices (IMDs). The IPDL system comprises an external device placed on exterior to human skin to transmitting power and data to IMDs like implantable micro-systems (cardiac pacemakers, cochlear implants, retinal implants, deep brain stimulators) to excite and monitor respective neural and muscular system. The entire system is designed to operate with a ‘low-band-frequency’ of 4 MHz by avoiding the problem of tissue heating. A practical model for the IPDL with results is presented. Various graphs such as frequency vs primary coil/secondary coil output are plotted and shown. Typical specifications of the exterior device, namely, the modulation-index (MI) and the modulation-rate (MR) are 40% and 4.3% respectively with a data rate of 172 Kbps. The design is simulated with electronic workbench MULTISIM 12.0 and TINA Ver 9.