Thermal Tissue Damage Research Articles

Engineering Coatings Inspired by Cell Membrane Thermal Dynamics to Enhance Photothermal Therapy and Osteogenesis for Implant Infections.

Photothermal therapy (PTT) encounters challenges of rapid thermal loss and potential tissue damage. In response, we propose a Heat-Boost and Lock implant coating strategy inspired by the thermal adaptation of biological membranes, enabling precise local photothermal utilization. This coating incorporates a poly(tannic acid) (pTA) bridging layer on implants, facilitating stable layer-by-layer integration of a black phosphorus (BP) photothermal layer and a top cell membrane Heat-Boost and Lock layer. The cell membrane layer significantly curtails photothermal loss (extending the heat retention by 17.62%) and stores energy within its phospholipid bilayer, boosting photothermal effects near implants (achieving a temperature increasement of 275%). Theoretical analysis indicates that these local heat preservation properties of the cell membrane arise from its low thermal conductivity and phase-change properties. In a Staphylococcus aureus-infected bone implant model, our coating demonstrates precise antibacterial action around implants (reach an antibacterial ratio of 99.52%). The synergetic locking function of cell membrane and pTA delays BP biodegradation, ensuring favorable photothermal stability and long-term osteo-inductive performance (increasing the bone volume fraction by 53.45%). Beyond providing an endogenic biointerface, this strategy extends the application of cell membrane in local thermal management, offering possibilities for effective and safe PTT modalities.

Numerical simulation of heat transfer properties of skin tissue acted on repetitive laser irradiation

Pulsed laser has been widely used in the clinical treatment of various diseases and injuries due to its unique advantages in the process of interaction with skin tissue. In order to ensure the therapeutic effect and patient safety, it is necessary to accurately monitor the time-space response of the whole-field temperature of the target tissue irradiated by pulsed laser. A research strategy to explore the thermal response and incidental thermal damage of skin tissue induced by repeated pulses laser has been proposed in present work. A theoretical model involved variable physical properties was first proposed, in which the dual-phase lag (DPL) equation and Henrique burn equation were employed to evaluate the tissue temperature and thermal damage induced by repeated pulse laser irradiation. With the help of finite difference method, the governing equation with variable physical properties was then numerical solved to obtain the time-space distribution of tissue temperature, and the evolution process of the thermal damage was further calculated. The effects of laser input parameters and variable physical parameters on the laser penetration depth, temperature distribution and burn degree of the irradiated tissue were analyzed.

Bio-thermal non-equilibrium dynamics and thermal damage in biological tissues induced by multiple time pulse-laser irradiations

BackgroundLaser therapy offers precise medical treatment by directing focused light beams to specific areas without harming surrounding tissue. This precision is particularly valuable in tissue treatment, including cancer therapy, where minimizing collateral damage is critical. The current study focuses on bio-thermal dynamics and thermal damage in biological tissues induced by multiple pulse-laser irradiations. ModelThe Local Thermal Non-Equilibrium (LTNE) bio-heat Transfer model with porosity and dual lag effects is developed to investigate the thermal behavior in tissues. The model contains partial differential equations that is solved through numerical method. ResultsObtained results show temperature variations and thermal damage in tissues, influenced by parameters such as laser intensity, incident duration, and tissue porosity. Higher intensity of laser and extended laser durations increase the temperature distribution and thermal damage. Porosity inversely affects temperature distribution, with large values of porosity leading to decreased distribution. NoveltyThis study introduces the application of multi-time lasers induced on tissue for the therapies, a novel approach that has not been previously explored in the literature.

Enhancing orthopedic outcomes: A comparative analysis of gentamicin sulphate and nanosilver in bone cement

BackgroundOrthopedic surgeries frequently utilize bone cement, which can increase the risk of postoperative infections. Addressing this challenge, this study aims to enhance the mechanical, physical, and handling properties of bone cement by integrating gentamicin sulfate (GS) and nanosilver (nAg). The objective is to evaluate and compare the effects of these additives on properties such as compressive strength, flexural strength, doughing time, working time, setting time, and exothermic temperature. By doing so, the study seeks to identify a safer and more effective alternative to traditional antibiotics in bone cement formulations, thereby improving clinical outcomes in orthopedic procedures. MethodsThis research involved a comparative analysis of modified cements against standard cements, focusing on compressive strength, flexural strength, doughing time, working time, setting time, and exothermic temperature. Various bone cement samples with GS and nAg additives were prepared and tested in accordance with international standards (ISO 5833:2002 and ASTM F451). Statistical analysis, including one-way and two-way ANOVA tests, was used to assess the significance of the results. ResultsnAg-loaded cements exhibit mechanical and physical properties on par with or supe-rior to those of GS-loaded and standard cements. Notably, nAg incorporation leads to significantly lower exothermic temperatures, reducing the risk of thermal bone tissue damage. This finding highlights that nAg-loaded cement is a safer alternative. Alongside unaltered or enhanced strength, nAgs demonstrate promise for orthopedic applications, particularly in primary arthroplasty. Additionally, nAgs reduce doughing time, enhancing the practicality of these methods in surgical settings. ConclusionsIn conclusion, this study underscores the potential advantages of incorporating GSs and nAgs into bone cement. nAg-loaded cement offers improved properties and reduced infection risk, making it a valuable choice for orthopedic procedures. It enhances both mechanical performance and safety, addressing crucial concerns in orthopedic surgery.

A new model of electrosurgical tissue damage for neurosurgery simulation

BackgroundBipolar hemostasis electrocoagulation is a fundamental procedure in neurosurgery. A precise electrocoagulation model is essential to enable realistic visual feedback in virtual neurosurgical simulation. However, existing models lack an accurate description of the heat damage and irreversible tissue deformation caused by electrocoagulation, thus diminishing the visual realism. This work focuses on the electrocoagulation model for neurosurgery simulation. MethodIn this paper, a position-based dynamics (PBD) model with a bioheat transfer and damage prediction (BHTDP) method is developed for simulating the deformation of brain tissue caused by electrocoagulation. The presented BTHDP method uses the Arrhenius equation to predict thermal damage of brain tissue. A deformation model with energy and thermal damage constraints is developed to characterize soft tissue deformation during heat absorption before and after thermal injury. Visual effect of damaged brain tissue is re-rendered. ResultTo evaluate the accuracy of the proposed method, numerical simulations were conducted and compared with commercial finite element software. The maximum normalized error of the proposed model for predicting midpoint temperature is 10.3 % and the maximum error for predicting the thermal damage is 5.4 %. The contraction effects of heat-exposed anisotropic tissues are also simulated. The results indicate that the presented electrocoagulation model provides stable and realistic visual effects, making it applicable for simulating the electrocoagulation process in virtual neurosurgery.

An experimental study on low-temperature plasma tissue ablation and its thermal effect

Low-temperature plasma ablation has been recently used for minimally invasive surgeries. However, more research is still needed on its generation process during tissue ablation and the underlying mechanism of tissue thermal damage. In this paper, high-speed camera footage, voltage–current signal collection, temperature analysis, and histological analysis were used to investigate the dynamic process of plasma tissue ablation and its thermal effect of dual-needle electrodes immersed in normal saline, which were driven by a high-frequency DC power supply with an output voltage ranging from 220 V to 320 V and a squire wave of 100 kHz. Microbubbles occurred around the ground electrode and merged to form a vapor layer that could completely cover the ground electrode. Plasma capable of ablating tissue would occur in the vapor layer between the ground electrode and tissue. The effect of electrical parameters on plasma generation and its thermal effect are analyzed by statistical results. The experimental results indicated that the voltage applied to the electrodes significantly influenced both the generation and stability of plasma, as well as the heat generation and tissue damage around the electrodes. Furthermore, under the same voltage, the existence of biological tissue promotes the formation of a vapor layer around the electrode, thereby facilitating the generation and stability of plasma. Notably, the temperature rise around the ground electrode is much higher than that around the powered electrode. These results have direct application to the design of plasma tissue ablation systems, which could achieve tissue ablation effects with minimal thermal damage.

Patient-specific temperature distribution prediction in laser interstitial thermal therapy: single-irradiation data-driven method

Laser interstitial thermal therapy (LITT) is popular for treating brain tumours and epilepsy. The strict control of tissue thermal damage extent is crucial for LITT. Temperature prediction is useful for predicting thermal damage extent. Accurately predicting in vivo brain tissue temperature is challenging due to the temperature dependence and the individual variations in tissue properties. Considering these factors is essential for improving the temperature prediction accuracy. Objective. To present a method for predicting patient-specific tissue temperature distribution within a target lesion area in the brain during LITT. Approach. A magnetic resonance temperature imaging (MRTI) data-driven estimation model was constructed and combined with a modified Pennes bioheat transfer equation (PBHE) to predict patient-specific temperature distribution. In the PBHE for temperature prediction, the individual specificity and temperature dependence of thermal tissue properties and blood perfusion, as well as the individual specificity of optical tissue properties were considered. Only MRTI data during one laser irradiation were required in the method. This enables the prediction of patient-specific temperature distribution and the resulting thermal damage region for subsequent ablations. Main results. Patient-specific temperature prediction was evaluated based on clinical data acquired during LITT in the brain, using intraoperative MRTI data as the reference standard. Our method significantly improved the prediction performance of temperature distribution and thermal damage region. The average root mean square error was decreased by 69.54%, the average intraclass correlation coefficient was increased by 37.5%, the average Dice similarity coefficient was increased by 43.14% for thermal damage region prediction. Significance. The proposed method can predict temperature distribution and thermal damage region at an individual patient level during LITT, providing a promising approach to assist in patient-specific treatment planning for LITT in the brain.

BiZact-Assisted Endoscopic Resection of a Sinonasal Tumor.

The BiZact device, a bipolar electrosurgical scissor designed for tonsillectomy, minimizes thermal tissue damage and seals blood vessels <3 mm in diameter while dividing the soft tissue. This study describes the authors' experience with sinonasal tumor surgery using a BiZact and discusses its clinical utility and advantages. The authors analyzed BiZact-assisted endoscopic sinonasal tumor surgery cases between January 2021 and May 2023. Data were collected on patients' demographics, histopathology, extent of tumor involvement, surgical records, and postoperative medical records. Clinical utility was assessed using the success rate of complete tumor excision, estimated blood loss during surgery, device-related complications, and operation time. A survey of the surgeons' BiZact experience was also conducted. The diagnoses of the 20 patients in this study included squamous cell carcinoma (n = 2), malignant melanoma (n = 1), sarcoma (n = 1), natural killer cell lymphoma (n = 1), inverted papilloma (n = 12), angiofibroma (n = 2), and schwannoma (n = 1). This pilot study demonstrated a shortened operative time, with a median of 0.8 hours and <100 mL of intraoperative blood loss. In addition, no BiZact-related complications were observed. The BiZact device allows efficient sinonasal surgery because it has the unique advantage of one-step sealing and cutting. BiZact-assisted endoscopic sinonasal tumor surgery is a beneficial and safe procedure that reduces blood loss during surgery, shortens the operative time, and minimizes postoperative complications.

WATTS happening? Evaluation of thermal dose during holmium laser lithotripsy in a high-fidelity anatomic model.

To evaluate the thermal profiles of the holmium laser at different laser parameters at different locations in an in vitro anatomic pelvicalyceal collecting system (PCS) model. Laser lithotripsy is the cornerstone of treatment for urolithiasis. With the prevalence of high-powered lasers, stone ablation efficiency has become more pronounced. Patient safety remains paramount during surgery. It is well recognized that the heat generated from laser lithotripsy has the potential to cause thermal tissue damage. Utilizing high-fidelity, 3D printed hydrogel models of a PCS with a synthetic BegoStone implanted in the renal pelvis, laser lithotripsy was performed with the Moses 2.0 holmium laser. At a standard power (40W) and irrigation pressure (100cm H2O), we evaluated operator duty cycle (ODC) variations with different time-on intervals at four different laser settings. Temperature was measured at two separate locations-at the stone and away from the stone. Temperatures were highest closest to the laser tip with a decrease away from the laser. Fluid temperatures increased with longer laser-on times and higher ODCs. Thermal doses were greater with increased ODCs and the threshold for thermal injury was reached for ODCs of 75% and 100%. Temperature generation and thermal dose delivered are greatest closer to the tip of the laser fiber and are not dependent on power alone. Significant temperature differences were noted between four laser settings at a standardized power (40W). Temperatures can be influenced by a variety of factors, such as laser-on time, operator duty cycle, and location in the PCS.

Comparison of temperature and renal tissue thermal damage by holmium laser with different energy parameters during lithotripsy: in vitro porcine kidney model.

Holmium laser percutaneous nephrolithotripsy was simulated by porcine kidney calculus model in vitro to investigate thermal damage of renal tissue by different energy parameters of the holmium laser. We placed human kidney calculus specimen in fresh vitro porcine kidney, then insert thermocouple temperature probes into the submucosa of the renal pelvis and reheated in a 37°C water bath. A percutaneous nephrological sheath was used to penetrate the renal parenchyma with a moderate irrigation rate of 30ml/min at 18℃. The Holmium laser was used to fragment the stones under a nephroscope, and the temperature was recorded. The four independent models were lithotripsy with 30W and 60W laser for 5 and 10min, respectively; the mean temperature of 30W vs. 60W within 5min was 36.06°C vs. 39.21°C (t = 5.36, P < 0.01) and the highest temperature was 43.60°C vs. 46.60°C; the mean temperature of 30W vs. 60W within 10min was 37.91°C vs. 40.13℃ (t = 5.28, P < 0.01), maximum temperature 46.80℃ vs. 49.20℃. Pathologically, each kidney was observed to have different degrees of thermal damage lesions, and the higher power and longer time the more severe the injury, but the injury was mainly limited to the uroepithelial and subepithelial tissues, with rare damage to renal tubules. The higher laser excitation power and longer duration raised the intrarenal temperature significantly and caused a certain degree of thermal damage to the kidney tissue, but overall it was found to be safe and reliable. Urologists can avoid further side effects through surgical expertise.

Correlation Between the Effects of CO2 Laser and Histopathological Analysis in Vocal Cord Lesions: An Observational Study.

Lasers are based on the principle of light amplification by empowering atoms to store and emit light in a coherent form. Through their effect on tissues, lasers reduce hemorrhage allowing the surgeon to work in a clear field with precise removal of the tissues. Irradiation of the soft tissues by lasers produces thermal effects on the surrounding healthy tissues which can make histopathological examination difficult. Hence this study was done to find a correlation between adjustable parameters of CO2 laser and the extent of collateral thermal damage in the excised vocal cord lesions on histopathological examination and diagnosis. In this study, we enrolled 80 patients who were divided into 4 groups with different combinations of laser power and mode, used during transoral laser micro laryngeal surgery for the excision of vocal cord lesions and subsequent histopathological analysis to objectively measure the extent of thermal damage zone and subjectively assess histo-morphological effects of thermal damage in terms of grade of carbonization. The extent of the thermal damage zone is directly related to the power of the laser, but the mode of the laser had no relation with the thermal damage zone in our study. On subjective histo-morphological examination of excised lesions showed that both power and mode of laser have significant effects on tissue morphology. Continuous mode causes a significantly higher grade of carbonization as compared to the superpulsed mode of the laser. However, in our study it was seen that charring in no way affected the diagnosis in any of the biopsies examined whatever the power or mode of the laser used. The depth and width of the tissue thermal damage zone are mainly dependent upon the laser parameters (power and mode). Although considering the limitations of this study carried out in terms of sample size, it would be pertinent to mention here that further studies with larger cohorts need to be done to authenticate these results.

Thermal Damage in Orthopaedics.

There are numerous potential sources of thermal damage encountered in orthopaedic surgery. An understanding of the preclinical mechanisms of thermal damage in tissues is necessary to minimize iatrogenic injuries and use these mechanisms therapeutically. Heat generation is a phenomenon that can be used to a surgeon's benefit, most commonly for hemostasis and local control of tumors. It is simultaneously one of the most dangerous by-products of orthopaedic techniques as a result of burring, drilling, cementation, and electrocautery and can severely damage tissues if used improperly. Similarly, cooling can be used to a surgeon's advantage in some orthopaedic subspecialties, but the potential for harm to tissues is also great. Understanding the potential of a given technique to rapidly alter local temperature-and the range of temperatures tolerated by a given tissue-is imperative to harness the power of heat and cold. In all subspecialties of orthopaedic surgery, thermal damage is a relevant topic that represents a direct connection between preclinical and clinical practice.

Machine learning-based high-frequency neuronal spike reconstruction from low-frequency and low-sampling-rate recordings

Recording neuronal activity using multiple electrodes has been widely used to understand the functional mechanisms of the brain. Increasing the number of electrodes allows us to decode more variety of functionalities. However, handling massive amounts of multichannel electrophysiological data is still challenging due to the limited hardware resources and unavoidable thermal tissue damage. Here, we present machine learning (ML)-based reconstruction of high-frequency neuronal spikes from subsampled low-frequency band signals. Inspired by the equivalence between high-frequency restoration and super-resolution in image processing, we applied a transformer ML model to neuronal data recorded from both in vitro cultures and in vivo male mouse brains. Even with the x8 downsampled datasets, our trained model reasonably estimated high-frequency information of spiking activity, including spike timing, waveform, and network connectivity. With our ML-based data reduction applicable to existing multichannel recording hardware while achieving neuronal signals of broad bandwidths, we expect to enable more comprehensive analysis and control of brain functions.

A novel electrode for reducing tissue thermal damage in radiofrequency-induced intestinal anastomosis

Purpose This study aimed to design a novel electrode for reducing tissue thermal damage in radiofrequency-induced intestinal anastomosis. Material and methods We developed and compared two electrodes (Ring electrode, and Plum electrode with reduced section of the middle fusion area by nearly 80% arising from novel structural design) by performing ex-vivo experiments and finite element analysis. Results In contrast to the Ring electrode group, slightly higher mean strength is acquired with the tensile force and burst pressure results increasing from 9.7 ± 1.47 N, 84.0 ± 5.99 mmHg to 11.1 ± 1.71 N, 89.4 ± 6.60 mmHg, respectively, as well as a significant reduction in tissue thermal damage for the Plum electrode group, with compression pressure of 20 kPa, RF energy of 120 W and welding duration of 8 s applied to the target regions to achieve anastomosis. Besides, the novel structural design of the Plum electrode can counteract the tension generated by intestinal peristalsis and enhance the biomechanical strength of the anastomotic area. The histological observation showed that the fusion area of the two-layer intestinal tissue is tightly connected with decreased thickness. Conclusion The novel electrode (Plum electrode) could reduce tissue thermal damage in radiofrequency-induced intestinal anastomosis.

Comparison of two advanced bipolar tissue sealer/dividers for laparoscopic ovariectomy in dogs: articulating enseal G2 versus Ligasure Maryland device

BackgroundAdvanced bipolar tissue sealer/dividers provide the most reliable and efficient means of tissue dissection and blood vessel sealing in laparoscopic surgery and the techniques are continuously improved. In veterinary practice, cost-effectiveness is of major impact, leading to re-use of instruments designed and sold for single use. Two high-end devices were evaluated and compared in a highly standardized laparoscopic ovariectomy procedure in dogs: The new generation Ligasure Maryland Sealer/Divider (LMSD) with improved atraumatic curved jaw shape for delicate tissue handling and dissection and non-stick nanocoating, and the new-generation Articulating Enseal G2 (AENG2) with several proclaimed features improving surgical performance, including articulation of the forceps tip; improved tissue compression during sealing; unique offset electrode configuration; and specific nanoparticle coating minimizing thermal spread and tissue sticking. Twenty-one client-owned dogs admitted for elective laparoscopic ovariectomy were randomly assigned to one of two groups: ovariectomy using AENG2 on the left ovary and LMSD in the right ovary or vice-versa. Procedural video recordings were used to assess ovarian ligament fat score, smoke formation, occurrence of bleeding, and excision duration. Excised tissues were examined histopathologically and collateral thermal damage was scored in three anatomic zones: suspensory ligament, vascular pedicle, and uterine junction. Tissue sealers were used repeatedly following standardized cleaning protocol with instrument washing machine and ethylene oxide gas sterilization and the number of uses until device failure was recorded.ResultsExcision times were significantly increased for AENG2 (median 01:35 min) compared to LMSD (median 01:00 min). Minor hemorrhage from incomplete sealing occurred in 3 sites in 2 patients (2x AENG2, 1x LMSD) and was not significantly different between groups. Smoke production as scored on videos and thermal tissue damage scores on histopathology also did not differ between AENG2 and LMSD. Both vessel sealers could be re-used repeatedly.ConclusionAENG2 provides a good alternative to LMSD in laparoscopic ovariectomy, with only minor differences in measured variables. Subjectively, the articulating feature of AENG2 did not improve surgical performance in laparoscopic ovariectomy and the use of LMSD appeared more straight-forward for this specific procedure. However, differences in operating these devices may be subject to personal preference.

Effect of the antenna slot numbers and position on the performance of microwave ablation

Microwave ablation (MWA) is a type of thermal ablation used for cancer treatment in interventional radiology. To induce localized tissue heating MWA employs electromagnetic waves within the microwave energy spectrum, which is done by the precisely designed antenna. This study substantially emphasizes the design and performance ameliorating of slot (both single and double) antennae and compares the results with conventional monopole antennae in terms of temperature distribution, specific absorption ratio (SAR), and thermal tissue damage rate. The simulation has been done in COMSOL by solving the Bioheat equation along with Maxwell electromagnetic equations using the finite element method. The simulation results reveal that the double-slot antenna has the most accurate and directional heat dissipation for liver tumors as well as the highest tissue damage rate and SAR. The highest SAR was found to be 3500 ​W/kg and 3350 ​W/kg at the implant depth of 61 ​mm and 63 ​mm for double and single-slot antennae, respectively. In addition, the fastest tissue damage occurred near the upper slot of the double-slot antenna. This study helps to understand the basic design parameters for enhancing single and double-slot antennae performance.

Thermal damage analysis in tissue caused by electromagnetic radiation using space–time collocation method

Over the past half-century, the usage of external heat sources in medical applications has increased substantially. Controlling heat damage is essential for ensuring the efficacy of the treatment. Living tissues are highly non-homogeneous; hence, it is important to take into account the effects of local non-equilibrium on their thermal behavior. In the present study, two- and three- space dimensional time-space fractional single-phase-lag (SPL) and dual-phase-lag (DPL) models for bio-heat transfer in tissue are considered to study the thermal damage and temperature in tissue caused by electromagnetic radiation as an external heat source. The considered mathematical models are more general and consider non-Fourier as well as non-local effects. We obtain the numerical solution for the models by combining Gaussian RBFs and shifted Chebyshev polynomials in the space and time directions, respectively. The RBFs depend on Euclidean distance, so they can easily be used in multidimensional space domain, and the use of Chebyshev polynomials gives spectral accuracy in time direction. It is also explored how different parameters, such as blood perfusion rate Wb, phase lags τq, τt, and fractional derivatives α, β, affect the temperature distribution and thermal damage in the tissue.

Experimental study of the effect of temperature on collagen conformational changes in skin tissue welded by femtosecond laser

In this study, in vitro skin tissues were welded using various laser settings at four temperature ranges, 30–40 °C, 40–60 °C, 60–80 °C, and > 80 °C., Raman spectra between 500 and 2000 cm−1 were examined in order to examine the relationship between the changes of collagen and the mechanical properties of skin tissue bonding and the degree of thermal damage of tissue. How collagen in skin tissues changed into disordered and less stable structures due to the thermal damage, and how the structure of protein and amino acid-related bands changed with increasing temperature were analyzed. Analysis of the deconvolution of the amide I band (1580–1720 cm−1) and the secondary structure of collagen showed that the secondary structure of collagen changed from α-like helix-dominated to β-aggregate-dominated structures due to the thermal damage. As the temperature increased, the number of protein molecule chain dissociation and reconnection within the skin tissue increased, which contributed to the improvement of the tensile strength of the skin after welding. However, when the temperature was too high, the collagen structure presented an extremely unstable state, and the degree of protein denaturation increased, causing serious thermal damage. When the skin tissue was welded using the femtosecond laser process parameters of laser power of 18 W, scanning speed of 50 mm/s, and scanning 50 times, the tensile strength of the in vitro skin tissue incision was greater and the degree of protein denaturation was less. The degree of thermal damage characterized by the degree of protein denaturation was consistent with that characterized by the microstructure texture characteristics parameters of the skin tissue.

A symplectic approach for the fractional heat transfer and thermal damage in 2D biological tissues

PurposeThis paper aims to focus on the accurate analysis of the fractional heat transfer in a two-dimensional (2D) rectangular monolayer tissue with three different kinds of lateral boundary conditions and the quantitative evaluation of the degree of thermal damage and burn depth.Design/methodology/approachA symplectic method is used to analytically solve the fractional heat transfer dual equation in the frequency domain (s-domain). Explicit expressions of the dual vector can be constructed by superposing the symplectic eigensolutions. The solution procedure is rigorously rational without any trial functions. And the accurate predictions of temperature and heat flux in the time domain (t-domain) are derived through numerical inverse Laplace transform.FindingsComparison study shows that the maximum relative error is less than 0.16%, which verifies the accuracy and effectiveness of the proposed method. The results indicate that the model and heat source parameters have a significant effect on temperature and thermal damage. The pulse duration (Δt) of the laser heat source can effectively control the time to reach the peak temperature and the peak slope of the thermal damage curve. The burn depth is closely correlated with exposure temperature and duration. And there exists the delayed effect of fractional order on burn depth.Originality/valueA symplectic approach is presented for the thermal analysis of 2D fractional heat transfer. A unified time-fractional heat transfer model is proposed to describe the anomalous thermal behavior of biological tissue. New findings might provide guidance for temperature prediction and thermal damage assessment of biological tissues during hyperthermia.

Nanoscale zerovalent Iron-incorporated kaolinite for hemostatic and antibacterial applications

Nanoscale zero-valent iron (nZVI) was converted into iron oxide and used as an active component in hemostasis, but have to avoid inefficient nano agglomerates and tissue thermal damage. Herein, a nZVI-kaolinite composite was fabricated with kaolinite as the support material through the sodium borohydride reduction method, and its multiple hemostatic mechanisms and broad-spectrum antibacterial activity were studied. Incorporated kaolinite improves the dispersed state in an appropriate spacing against the exothermic oxidation reaction in advance, reducing exothermic side effects within a tissue-tolerable allowance. Regarding the hemostatic properties of nZVI-incorporated kaolinite, the blood coagulation index was 4.10% to 7.30%, and the hemolysis rate in vitro was less than 5%. The hemostatic mechanism originates from negatively charged silanol groups on the kaolinite surface and the iron oxide nanoparticles oxidized from nZVI. In addition, broad-spectrum antibacterial activities were obtained in vitro due to the synergistic effect of nZVI particles and kaolinite, including physical adsorption, exothermic effects, and the generation of reactive oxygen species. This work offered a feasible idea for using nZVI to treat infectious wounds.