The numerical simulation of flow field around Hayabusa capsule loaded with light-weight ablator thermal response coupled with pyrolysis gas flow inside the ablator was carried out. In addition, the radiation from high...The numerical simulation of flow field around Hayabusa capsule loaded with light-weight ablator thermal response coupled with pyrolysis gas flow inside the ablator was carried out. In addition, the radiation from high temperature gas around the capsule was coupled with flow field. Hayabusa capsule reentered the atmosphere about 12 km/sec in velocity and Mach number about 30. During such an atmospheric entry, space vehicle is exposed to very savior aerodynamic heating due to convection and radiation. In this study, Hayabusa capsule was treated as a typical model of the atmospheric entry spacecraft. The light-weight ablator had porous structure, and permeability was an important parameter to analyze flow inside ablator. In this study, permeability was a variable parameter dependent on density of ablator. It is found that the effect of permeability of light-weight ablator was important with this analysis.展开更多
Radiofrequency ablation(RFA),particularly endoscopic ultrasound-guided RFA(EUS-RFA),has emerged as a promising minimally invasive approach for the treatment of pancreatic cancer,especially in patients with locally adv...Radiofrequency ablation(RFA),particularly endoscopic ultrasound-guided RFA(EUS-RFA),has emerged as a promising minimally invasive approach for the treatment of pancreatic cancer,especially in patients with locally advanced or unresectable disease.This review outlines recent technological developments in EUS-RFA,including innovations in energy delivery systems,probe design,and real-time thermal monitoring,which have improved the precision and safety of the procedure.Clinical studies combining EUS-RFA with chemotherapy have demonstrated encouraging outcomes,with improvements in overall survival,progression-free survival,tumor necrosis,and symptom control compared to chemotherapy alone.Additionally,RFA-induced tumor antigen release and modulation of the tumor microenvironment suggest a potential synergistic role with immunotherapy.Despite its promise,the widespread adoption of EUS-RFA is limited by a lack of large-scale randomized controlled trials and standardized treatment protocols.展开更多
Hydrodynamic instability growth at the deuterium-tritium(DT)fuel-ablator interface plays a critical role in determining the performance of inertial confinement fusion implosions.During the late stages of implosion,ins...Hydrodynamic instability growth at the deuterium-tritium(DT)fuel-ablator interface plays a critical role in determining the performance of inertial confinement fusion implosions.During the late stages of implosion,insufficient doping of the ablator material can result in highenergy X-ray preheat,which may trigger the development of a classical-like Rayleigh-Taylor instability(RTI)at the fuel-ablator interface.In implosion experiments at the Shenguang 100 kJ-level laser facility,the primary source of perturbation is the roughness of the inner DT ice interface.In this study,we propose an analytical model to describe the feed-out process of the initial roughness of the inner DT ice interface.The perturbation amplitude derived from this model serves as the initial seed for the late-time RTI during the acceleration phase.Our findings confirm the presence of classical-like RTI at the fuel-ablator interface.Numerical simulations conducted using a radiation hydrodynamic code validate the proposed analytical model and demonstrate the existence of a peak mode number in both the feed-out process and the classical-like RTI.It provides an alternative bridge between the current target fabrication limitations and the unexpected implosion performance.展开更多
BACKGROUND Data comparing the outcomes of hepatocellular carcinoma(HCC)ablation by multibipolar radiofrequency ablation(mbp-RFA)and microwave ablation(MWA)are lacking.This study compares safety and efficacy of the two...BACKGROUND Data comparing the outcomes of hepatocellular carcinoma(HCC)ablation by multibipolar radiofrequency ablation(mbp-RFA)and microwave ablation(MWA)are lacking.This study compares safety and efficacy of the two techniques in treatment-naive HCC.AIM To compare the risk of local tumor progression(LTP)according to the technique;secondary endpoints included technique efficacy rate at one-month,overall survival and major complication rate.METHODS A bi-institutional retrospective analysis of patients undergoing treatment-naive HCC ablation by either technique was performed.Inverse probability of treatment weighting was used to compare the two groups.Mixed effects multivariate Cox regression was applied to identify risk factors for LTP.RESULTS A total of 362 patients(mean age,66.1±6.2 years,308 men)were included,of which 242(323 tumors)treated by mbp-RFA and 120(168 tumors)by MWA.After a median follow-up of 27 months,cumulative LTP was 11.4%after mbp-RFA and 25.2%after MWA.Independent risk factors for LTP at multivariate analysis were MWA(hazard ratio=2.85,P<0.001)and tumor size(hazard ratio=1.08,P<0.001).Two-year LTP-free survival was higher after mbp-RFA than MWA regardless of size(<3 cm:96%vs 87.1%,P<0.01;≥3 cm:87.5%vs 74%,P=0.04).Technique efficacy rate was higher after mbp-RFA(94.1%vs 87.5%,P=0.01).No difference was observed in major complication rate(9.5%vs 7.5%,P=0.59),nor 5-year overall survival(63.6%vs 58.3%,P=0.33).CONCLUSION Mbp-RFA leads to better local tumor control of treatment-naïve HCC than MWA regardless of tumor size and has better primary efficacy,while maintaining a comparable safety profile.展开更多
Colorectal cancer(CRC)with lung oligometastases,particularly in the presence of extrapulmonary disease,poses considerable therapeutic challenges in clinical practice.We have carefully studied the multicenter study by ...Colorectal cancer(CRC)with lung oligometastases,particularly in the presence of extrapulmonary disease,poses considerable therapeutic challenges in clinical practice.We have carefully studied the multicenter study by Hu et al,which evaluated the survival outcomes of patients with metastatic CRC who received image-guided thermal ablation(IGTA).These findings provide valuable clinical evidence supporting IGTA as a feasible,minimally invasive approach and underscore the prognostic significance of metastatic distribution.However,the study by Hu et al has several limitations,including that not all pulmonary lesions were pathologically confirmed,postoperative follow-up mainly relied on dynamic contrast-enhanced computed tomography,no comparative analysis was performed with other local treatments,and the impact of other imaging features on efficacy and prognosis was not evaluated.Future studies should include complete pathological confirmation,integrate functional imaging and radiomics,and use prospective multicenter collaboration to optimize patient selection standards for IGTA treatment,strengthen its clinical evidence base,and ultimately promote individualized decision-making for patients with metastatic CRC.展开更多
Lightweight and high-toughness carbon fiber/phenolic ablator(CFPA)is required as the Thermal Protection System(TPS)material of aerospace vehicles for next-generation space missions.To improve the ablative properties,s...Lightweight and high-toughness carbon fiber/phenolic ablator(CFPA)is required as the Thermal Protection System(TPS)material of aerospace vehicles for next-generation space missions.To improve the ablative properties,silica sol with good particle size distribution prepared using tetramethoxysilane(TMOS)was blended with natural rubber latex and deposited onto carbon fiber felt,which was then integrated with phenolic aerogel matrix,introducing nano-silica into the framework of CFPA.The modified CFPA with a low density of 0.28—0.31 g/cm3exhibits strain-in-fracture as high as 31.2%and thermal conductivity as low as 0.054 W/(m·K).Furthermore,a trace amount of nano-silica could effectively protect CFPA from erosion of oxidizing atmosphere in different high-temperature environments.The oxyacetylene ablation test of 3000°C for 20 s shows a mass ablation rate of 0.0225 g/s,a linear ablation rate of 0.209 mm/s for the modified CFPA,which are 9.64%and 24.82%lower than the unmodified one.Besides,the long-time butane ablation test of 1200°C for 200 s shows an insignificant recession with mass and linear ablation rate of 0.079 g/s and 0.039 mm/s,16.84%and 13.33%lower than the unmodified one.Meanwhile,the fixed thermocouple in the test also demonstrates a good thermal insulation performance with a low peak back-face temperature of 207.7°C,12.25%lower than the unmodified one.Therefore,the nano-silica modified CFPA with excellent overall performance presents promising prospects in high-temperature aerospace applications.展开更多
The paper investigates theoretically the optimization of the doped ablator layers for the plastic ignition capsule. The high-resolved one-dimensional implosion simulations show that the inner pure CFI layer of the Si-...The paper investigates theoretically the optimization of the doped ablator layers for the plastic ignition capsule. The high-resolved one-dimensional implosion simulations show that the inner pure CFI layer of the Si-doped design is excessively preheated by the hard x-ray, leading to the unstable ablator-fuel interface compared to the Ge-doped capsule. This is because that the Si K-shell absorption edge （1.8 keV） is higher than the Ge L-edge （1.3 keV）, and Si dopant makes more hard x-ray penetrate through the doped ablator layers to preheat the inner pure CH layer. So an optimization of the doped ablator layers （called ＂Si/Ge capsule＂） is performed： an Si-doped CH layer is placed next to the outer pure CH layer to keep the high implosion velocity; next to the Si-doped layer is a thin Ge-doped layer, in order to absorb the hard x-ray and protect the inner undoped CH-layer from excessively preheating. The simulations show that the Si/Ge capsule can effectively improve hydrodynamic stability at the ablator-fuel interface while keeping the high implosion velocity.展开更多
BACKGROUND Duodenal mucosal ablation(DMA)using irreversible electroporation(IRE)with a glucagon-like peptide-1 receptor agonist has been clinically shown to reduce liver lipid deposition in non-alcoholic fatty liver d...BACKGROUND Duodenal mucosal ablation(DMA)using irreversible electroporation(IRE)with a glucagon-like peptide-1 receptor agonist has been clinically shown to reduce liver lipid deposition in non-alcoholic fatty liver disease(NAFLD).However,the specific metabolic contributions of DMA using IRE in NAFLD remain unclear.AIM To assess the feasibility and effectiveness of DMA using IRE in NAFLD rat models.METHODS Seven-week-old male Sprague-Dawley rats underwent DMA using IRE after 8 weeks on a high-fat diet.Two weeks post-treatment,duodenal and liver tissues and blood samples were collected.We evaluated differences in the duodenal wall structure,liver lipid deposition,enteroendocrine,claudin,and zonula ocludens-1 in the duodenal mucosa.RESULTS DMA using IRE could be safely performed in rats with NAFLD without duodenal bleeding,perforation,or stenosis.The duodenum healed well 2 weeks after DMA and was characterized by slimmer villi,narrower and shallower crypts,and thicker myenterons compared with the sham-control setting.Liver lipid deposition was reduced and serum lipid index parameters were considerably improved in the DMA setting.However,these improvements were independent of food intake and weight loss.In addition,enteroendocrine parameters,such as claudin,and zonula ocludens-1 levels in the duodenal mucosa,differed between the different settings in the DMA group.CONCLUSION By altering enteroendocrine and duodenal permeability,simple DMA using IRE ameliorated liver lipid deposition and improved serum lipid parameters in NAFLD rats.展开更多
Multicomponent(Hf-Zr-Ta)B_(2)potentially provides improved ablation resistance compared with silicon-based ceramics.Here we deposited(Hf_(0.5-x/2)Zr_(0.5-x/2)Ta_(x))B_(2)(x=0,0.1,and 0.2)coatings onto C/C com-posites,...Multicomponent(Hf-Zr-Ta)B_(2)potentially provides improved ablation resistance compared with silicon-based ceramics.Here we deposited(Hf_(0.5-x/2)Zr_(0.5-x/2)Ta_(x))B_(2)(x=0,0.1,and 0.2)coatings onto C/C com-posites,and investigated their ablation behaviors under an oxyacetylene torch with a heat flux of 2.4 MW m^(-2).It was observed that the x=0.1 oxide scale bulged but was denser,and the x=0.2 oxide scale was blown away due to the formation of excessive liquid.Based on these findings,we further de-veloped a duplex(Hf-Zr-Ta)B_(2)coating that showed a linear recession rate close to zero(0.11μm s^(-1))after two 120-s ablation cycles.It is identified that the resulting oxide scale is mainly composed of(Hf,Zr)_(6)Ta_(2)O_(17)and(Hf,Zr,Ta)O_(2)by performing aberration-corrected(scanning)transmission electron microscopy.The protective mechanism is related to the peritectic transformation of orthorhombic-(Hf,Zr)_(6)Ta_(2)O_(17)to tetragonal-(Hf,Zr,Ta)O_(2)plus Ta-dominated liquid.This study contributes to the develop-ment of Ta-containing multicomponent UHTC bulk and coatings for ultra-high temperature applications.展开更多
Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety a...Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety and flight status of hypersonic vehicles.We numerically analyzes the mesoscopic ablation-erosion of C/C Composites with Inclined Fibers(CCIF).First,a thermochemical ablation model describing the reaction-diffusion coupled problem of C/C composites on mesoscale is employed to analyze ablative process,and the corresponding surface ablation morphology is obtained.Then,the ablation morphology of CCIF is taken as the geometrical model for mechanical erosion analysis,and their damage and failure behavior under high-speed airflow shear is analyzed by using progressive damage method.Moreover,the effects of fiber inclined angle and airflow direction on the mechanical erosion of CCIF are investigated,and the ablationerosion behavior is analyzed and discussed.The results show that the failure modes of mechanical erosion in inner and edge regions are obviously different,showing granular and block erosion phenomena respectively.The mechanical erosion of CCIF in the direction of reverse flow is easier than that in the direction of forward flow.These results can provide a theoretical basis for the design and optimization of thermal protection system materials.展开更多
The ablative material is supposed to be one of good candidates for LRE （liquid rocket engine） combustion chamber to achieve both high reliability and low cost and a numerical analysis for the ablator is considered t...The ablative material is supposed to be one of good candidates for LRE （liquid rocket engine） combustion chamber to achieve both high reliability and low cost and a numerical analysis for the ablator is considered to be a potentially efficient tool to reduce cost as well. So far, ablators have been successfully applied for many SRM （solid rocket motors）, but the application to LRE is still quite limited in Japan. The authors believe that this is primarily because of the unpredictable nature of the heat load from combustion gases to the combustor wall. Indeed, reliable thermal design of ablative combustion chamber, namely reliable prediction of thermal performance, needs both reliable heat load model and reliable ablator response model. This paper elaborates our research activities and our recent research findings.展开更多
This editorial comments on a study by Zuo et al.The focus is on the efficacy of he-patic arterial infusion chemotherapy combined with camrelizumab and apatinib(the TRIPLET regimen),alongside microwave ablation therapy...This editorial comments on a study by Zuo et al.The focus is on the efficacy of he-patic arterial infusion chemotherapy combined with camrelizumab and apatinib(the TRIPLET regimen),alongside microwave ablation therapy,in treating advanced hepatocellular carcinoma(HCC).The potential application of this combination therapy for patients with advanced HCC is evaluated.展开更多
Objective: To assess the predictors of successful inactivation of benign thyroid nodules using radiofrequency ablation (RFA) and the hormonal responses thereafter. Methods: A retrospective study conducted at Zhongnan ...Objective: To assess the predictors of successful inactivation of benign thyroid nodules using radiofrequency ablation (RFA) and the hormonal responses thereafter. Methods: A retrospective study conducted at Zhongnan Hospital of Wuhan University (January 2022 to January 2024) analysed thyroid tumor characteristics using B-mode ultrasound, colour Doppler imaging, and CEUS post-RFA. Thyroid hormone levels were also assessed before RFA and at 1, 3, and 6 months after the procedure. Results: The study involved 72 patients with benign thyroid nodules, comprising 13 males and 59 females, with a mean age of 45.8 ± 12.1 years. Complete inactivation was achieved in 70.8% of nodules, while 29.2% showed partial inactivation. Nodules with complete inactivation exhibited more calcification (p = 0.040), whereas those with partial inactivation demonstrated higher vascularity (p Conclusion: In conclusion, this study found that therapeutic RFA effectively achieves high rates of complete inactivation in benign thyroid nodules, with the degree of inactivation mainly influenced by nodule vascularity and calcifications.展开更多
Ultrasound-guided percutaneous thermal ablation has gained popularity as treatment for malignant hepatic tumors.It was first introduced as ablation therapy for hepatocellular carcinoma and cirrhosis comorbidity.Recent...Ultrasound-guided percutaneous thermal ablation has gained popularity as treatment for malignant hepatic tumors.It was first introduced as ablation therapy for hepatocellular carcinoma and cirrhosis comorbidity.Recently,this technique has also been used in the treatment of intrahepatic cholangiocarcinoma for patients who are not eligible for surgical resection.There are several types of thermal ablation techniques.Radiofrequency ablation and microwave ablation are two common methods that induce necrosis of the lesions.Irreversible electroporation is a relatively new non-thermal technique and is suitable in cases where thermal ablation would be ineffective or dangerous(e.g.,malignant tumors close to vascular or biliary structures).Irreversible electroporation can induce tumoral necrosis without damage to vascular and biliary structures.The aim of this minireview was to describe the safety,efficacy,and clinical indications of these techniques in the treatment of patients with intrahepatic cholangiocarcinoma who are ineligible for surgery.展开更多
BACKGROUND Atrial fibrillation,affecting approximately 33 million people globally,is the most common sustained arrhythmia,increasing risks of stroke,heart failure,and mortality.Pulmonary vein isolation via catheter ab...BACKGROUND Atrial fibrillation,affecting approximately 33 million people globally,is the most common sustained arrhythmia,increasing risks of stroke,heart failure,and mortality.Pulmonary vein isolation via catheter ablation is a key rhythm control strategy,with cryoballoon ablation(CBA)being a standard thermal method but associated with risks like phrenic nerve palsy(5%-10%),esophageal injury,and vein stenosis.Pulsed field ablation(PFA),a non-thermal technique using electrical pulses for selective electroporation,offers potential for shorter procedures and improved safety.Limited direct comparisons between PFA and CBA necessitate a systematic evaluation of their efficacy and safety.AIM To compare the procedural success,safety,and 1-year arrhythmia-free survival of PFA vs CBA for first-time pulmonary vein isolation in adults with paroxysmal or persistent atrial fibrillation.METHODS A Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review and metaanalysis was conducted,searching PubMed,EMBASE,Web of Science,and other databases up to August 2025 for comparative studies.Pooled mean difference for continuous outcomes and odds ratio(OR)for dichotomous outcomes were calculated using random-effects models.Study quality was assessed with the Newcastle-Ottawa Scale,heterogeneity with I2,and publication bias with funnel plots.RESULTS Seven studies(six cohorts,one randomized controlled trial)were included,with a mean age of approximately 66 years,59%-78%male,and high prevalence of hypertension and diabetes.PFA significantly reduced procedure time(mean difference=-15.24 minutes,95%CI:-16.63 to-13.85,P<0.00001;I2=89%),improved arrhythmia-free survival(OR=1.27,95%CI:1.04-1.55,P=0.02;I2=45%),and lowered phrenic nerve palsy risk(OR=0.17,95%CI:0.04-0.63,P=0.008;I2=0%).No significant differences were found in fluoroscopy time,cardiac tamponade,repeat ablation,or vascular complications.CONCLUSION PFA demonstrates shorter procedure times,reduced phrenic nerve palsy,and better arrhythmia control compared to CBA,with comparable safety profiles.However,evidence is limited by observational study designs,heterogeneity,and potential bias.Large-scale randomized controlled trials with extended follow-up are needed to confirm these findings and guide clinical practice.展开更多
To improve the compactness and properties of C/C-SiC-ZrC composites produced by precursor infiltration and pyrolysis(PIP)method,the low-temperature reactive melt infiltration(RMI)process was used to seal the composite...To improve the compactness and properties of C/C-SiC-ZrC composites produced by precursor infiltration and pyrolysis(PIP)method,the low-temperature reactive melt infiltration(RMI)process was used to seal the composites using Zr_(2)Cu as the filler.The microstructure,mechanical properties,and ablation properties of the Zr_(2)Cu packed composites were analyzed.Results show that during Zr_(2)Cu impregnation,the melt efficiently fills the large pores of the composites and is converted to ZrCu due to a partial reaction of zirconium with carbon.This results in an increase in composite density from 1.91 g/cm^(3)to 2.24 g/cm^(3)and a reduction in open porosity by 27.35%.Additionally,the flexural strength of Zr_(2)Cu packed C/C-SiC-ZrC composites is improved from 122.78±8.09 MPa to 135.53±5.40 MPa.After plasma ablation for 20 s,the modified composites demonstrate superior ablative resistance compared to PIP C/C-SiC-ZrC,with mass ablation and linear ablation rates of 2.77×10^(−3)g/s and 2.60×10^(−3)mm/s,respectively.The“selftranspiration”effect of the low-melting point copper-containing phase absorbs the heat of the plasma flame,further reducing the ablation temperature and promoting the formation of refined ZrO_(2)particles within the SiO_(2)melting layer.This provides more stable erosion protection for Zr_(2)Cu packed C/C-SiC-ZrC composites.展开更多
Microwave ablation(MWA)is emerging as a highly effective treatment for colorectal liver metastases(CRLMs).This review explores the advantages of MWA compared to other ablative techniques such as radiofrequency ablatio...Microwave ablation(MWA)is emerging as a highly effective treatment for colorectal liver metastases(CRLMs).This review explores the advantages of MWA compared to other ablative techniques such as radiofrequency ablation and cryoablation and highlights its clinical efficacy,safety,and technical considerations.MWA offers significant benefits,including higher intratumoral temperatures,larger ablation zones,and reduced susceptibility to the heat-sink effect,which make it particularly suitable for tumors near large blood vessels.This review details the patient selection criteria,procedural approaches,and the use of advanced imaging techniques to improve the precision and effectiveness of MWA.Clinical outcomes indicate that MWA achieves high rates of complete tumor ablation and long-term survival with a favorable safety profile.This review is significant because it provides updated insights into the expanding role of MWA in treating unresectable CRLM and its potential as an alternative to surgical resection for resectable tumors.By summarizing recent studies and clinical trials,this review highlights the comparative effectiveness,safety,and integration with systemic therapies of MWA.In conclusion,MWA is a promising treatment option for CRLM and offers outcomes comparable to or better than those of other ablative techniques.Future research should focus on optimizing technical parameters,integrating MWA with systemic therapies,and conducting large-scale randomized controlled trials to establish standardized treatment protocols.Advancing our understanding of MWA will enhance its application and improve long-term survival and quality of life for patients with CRLM.展开更多
Objective: To evaluate the efficacy of endovenous radiofrequency ablation (RFA) and laser ablation (EVLA) in the treatment of superficial varicose veins of the lower extremities. Methods: Seventy-eight patients with s...Objective: To evaluate the efficacy of endovenous radiofrequency ablation (RFA) and laser ablation (EVLA) in the treatment of superficial varicose veins of the lower extremities. Methods: Seventy-eight patients with superficial varicose veins treated at a hospital between April 2022 and May 2023 were selected and divided into a radiofrequency ablation group (RFA group;39 cases) and a laser ablation group (EVLA group;39 cases) based on the treatment method. Operation time, postoperative recovery duration, venous clinical severity score (VCSS) changes, complication rates, closure rates, and recurrence rates were compared between the groups at 1 month, 3 months, and 12 months postoperatively. The postoperative therapeutic outcomes were comprehensively evaluated. Results: No significant differences in age, gender, disease grade, or disease course were observed between the groups (P > 0.05). The superficial varicose vein closure rate was 100% in both groups at 1 and 3 months postoperatively. At 12 months, the closure rate was 94.87% in the RFA group and 97.43% in the EVLA group, with no statistically significant difference (P > 0.05). No significant differences were observed in VCSS changes or complication incidence between the groups (P > 0.05). Conclusion: Radiofrequency ablation and laser ablation demonstrate comparable efficacy and safety in the treatment of superficial varicose veins of the lower extremities.展开更多
The current generation of ultrahigh temperature ceramic precursors typically encounters obstacles in achieving high ceramic yields(<40 wt.%)due to the challenges in integrating significant amounts of boron,which ha...The current generation of ultrahigh temperature ceramic precursors typically encounters obstacles in achieving high ceramic yields(<40 wt.%)due to the challenges in integrating significant amounts of boron,which hampers their conversion into boride-based ultrahigh temperature ceramics.To tackle these challenges,a serious of pioneering liquid multi-component hafnium-containing ceramic SiHfCB precursors(with different Hf/Si ratios)have been developed.These novel precursors are featured with stable molec-ular structure and high ceramic yield which were successfully created through a novel one-pot polymer-ization process.They present in liquid form and their structure is characterized by C-C bonds forming its main chain with branched chains of O-Si-O,Si-O-Hf,Si-O-B,and B-O-Hf which have untapped advantages including uniform component dispersion,and excellent fluidity.The ceramic yield of SiHfCB precursor with Hf/Si of 0.2 is remarkably up to 68.6 wt.%at 1500℃,and their Hf content exceeded 50 wt.%.Of particular interest,the pyrolyzed product HfB_(2)-SiC nanopowders derived from the SiHfCB precursor with Hf/Si of 0.2,consist of nanopowders in the 40-60 nm range with a density of 5.23 g cm^(−3).Remarkably,this material demonstrates exceptional performance in ultrahigh temperature oxygen-containing environ-ments at 2500℃,showing near-zero ablation with a linear ablation rate of just 2.5×10^(−4) mm s^(−1).Post-ablation analysis of the microstructure reveals that the formation of a lava-like HfO_(2) and HfO_(2)-SiO_(2) oxide layer effectively blocks oxygen penetration and provides excellent oxidation resistance.The inno-vative SiHfCB hafnium-containing ceramic precursor offers a groundbreaking solution for the preparation of lightweight ultrahigh-temperature ceramics.This development is poised to provide robust technical support for the use of ultrahigh temperature ceramics in non-ablative thermal protective systems,partic-ularly in the construction of hypersonic vehicles,where ultrahigh temperature resilience is crucial.展开更多
Purpose:The major limitation of tumor microwave ablation(MWA)operation is the lack of predictability of the ablation zone before surgery.Operators rely on their individual experience to select a treatment plan,which i...Purpose:The major limitation of tumor microwave ablation(MWA)operation is the lack of predictability of the ablation zone before surgery.Operators rely on their individual experience to select a treatment plan,which is prone to either inadequate or excessive ablation.This paper aims to establish an ablation prediction model that guides MWA tumor surgical planning.Methods:An MWA process was first simulated by incorporating electromagnetic radiation equations,thermal equations,and optimized biological tissue parameters(dynamic dielectric and thermophysical parameters).The temperature distributions(the short/long diameters,and the total volume of the ablation zone)were then generated and verified by 60 cases ex vivo porcine liver experiments.Subsequently,a series of data were obtained from the simulated temperature distributions and to further fit the novel ablation coagulated area prediction model(ACAPM),thus rendering the ablation-dose table for the guiding surgical plan.The MWA clinical patient data and clinical devices suggested data were used to validate the accuracy and practicability of the established predicted model.Results:The 60 cases ex vivo porcine liver experiments demonstrated the accuracy of the simulated temperature distributions.Compared to traditional simulation methods,our approach reduces the long-diameter error of the ablation zone from 1.1 cm to 0.29 cm,achieving a 74%reduction in error.Further,the clinical data including the patients'operation results and devices provided values were consistent well with our predicated data,indicating the great potential of ACAPM to assist preoperative planning.展开更多
文摘The numerical simulation of flow field around Hayabusa capsule loaded with light-weight ablator thermal response coupled with pyrolysis gas flow inside the ablator was carried out. In addition, the radiation from high temperature gas around the capsule was coupled with flow field. Hayabusa capsule reentered the atmosphere about 12 km/sec in velocity and Mach number about 30. During such an atmospheric entry, space vehicle is exposed to very savior aerodynamic heating due to convection and radiation. In this study, Hayabusa capsule was treated as a typical model of the atmospheric entry spacecraft. The light-weight ablator had porous structure, and permeability was an important parameter to analyze flow inside ablator. In this study, permeability was a variable parameter dependent on density of ablator. It is found that the effect of permeability of light-weight ablator was important with this analysis.
文摘Radiofrequency ablation(RFA),particularly endoscopic ultrasound-guided RFA(EUS-RFA),has emerged as a promising minimally invasive approach for the treatment of pancreatic cancer,especially in patients with locally advanced or unresectable disease.This review outlines recent technological developments in EUS-RFA,including innovations in energy delivery systems,probe design,and real-time thermal monitoring,which have improved the precision and safety of the procedure.Clinical studies combining EUS-RFA with chemotherapy have demonstrated encouraging outcomes,with improvements in overall survival,progression-free survival,tumor necrosis,and symptom control compared to chemotherapy alone.Additionally,RFA-induced tumor antigen release and modulation of the tumor microenvironment suggest a potential synergistic role with immunotherapy.Despite its promise,the widespread adoption of EUS-RFA is limited by a lack of large-scale randomized controlled trials and standardized treatment protocols.
基金funded by the National Key R&D Program of China(Grant No.2023YFA1608400)the National Natural Science Foundation of China(Grant No.12302281).
文摘Hydrodynamic instability growth at the deuterium-tritium(DT)fuel-ablator interface plays a critical role in determining the performance of inertial confinement fusion implosions.During the late stages of implosion,insufficient doping of the ablator material can result in highenergy X-ray preheat,which may trigger the development of a classical-like Rayleigh-Taylor instability(RTI)at the fuel-ablator interface.In implosion experiments at the Shenguang 100 kJ-level laser facility,the primary source of perturbation is the roughness of the inner DT ice interface.In this study,we propose an analytical model to describe the feed-out process of the initial roughness of the inner DT ice interface.The perturbation amplitude derived from this model serves as the initial seed for the late-time RTI during the acceleration phase.Our findings confirm the presence of classical-like RTI at the fuel-ablator interface.Numerical simulations conducted using a radiation hydrodynamic code validate the proposed analytical model and demonstrate the existence of a peak mode number in both the feed-out process and the classical-like RTI.It provides an alternative bridge between the current target fabrication limitations and the unexpected implosion performance.
文摘BACKGROUND Data comparing the outcomes of hepatocellular carcinoma(HCC)ablation by multibipolar radiofrequency ablation(mbp-RFA)and microwave ablation(MWA)are lacking.This study compares safety and efficacy of the two techniques in treatment-naive HCC.AIM To compare the risk of local tumor progression(LTP)according to the technique;secondary endpoints included technique efficacy rate at one-month,overall survival and major complication rate.METHODS A bi-institutional retrospective analysis of patients undergoing treatment-naive HCC ablation by either technique was performed.Inverse probability of treatment weighting was used to compare the two groups.Mixed effects multivariate Cox regression was applied to identify risk factors for LTP.RESULTS A total of 362 patients(mean age,66.1±6.2 years,308 men)were included,of which 242(323 tumors)treated by mbp-RFA and 120(168 tumors)by MWA.After a median follow-up of 27 months,cumulative LTP was 11.4%after mbp-RFA and 25.2%after MWA.Independent risk factors for LTP at multivariate analysis were MWA(hazard ratio=2.85,P<0.001)and tumor size(hazard ratio=1.08,P<0.001).Two-year LTP-free survival was higher after mbp-RFA than MWA regardless of size(<3 cm:96%vs 87.1%,P<0.01;≥3 cm:87.5%vs 74%,P=0.04).Technique efficacy rate was higher after mbp-RFA(94.1%vs 87.5%,P=0.01).No difference was observed in major complication rate(9.5%vs 7.5%,P=0.59),nor 5-year overall survival(63.6%vs 58.3%,P=0.33).CONCLUSION Mbp-RFA leads to better local tumor control of treatment-naïve HCC than MWA regardless of tumor size and has better primary efficacy,while maintaining a comparable safety profile.
文摘Colorectal cancer(CRC)with lung oligometastases,particularly in the presence of extrapulmonary disease,poses considerable therapeutic challenges in clinical practice.We have carefully studied the multicenter study by Hu et al,which evaluated the survival outcomes of patients with metastatic CRC who received image-guided thermal ablation(IGTA).These findings provide valuable clinical evidence supporting IGTA as a feasible,minimally invasive approach and underscore the prognostic significance of metastatic distribution.However,the study by Hu et al has several limitations,including that not all pulmonary lesions were pathologically confirmed,postoperative follow-up mainly relied on dynamic contrast-enhanced computed tomography,no comparative analysis was performed with other local treatments,and the impact of other imaging features on efficacy and prognosis was not evaluated.Future studies should include complete pathological confirmation,integrate functional imaging and radiomics,and use prospective multicenter collaboration to optimize patient selection standards for IGTA treatment,strengthen its clinical evidence base,and ultimately promote individualized decision-making for patients with metastatic CRC.
基金partly supported by the National Natural Science Foundation of China(Grant Nos.22178107,U21A2060,22178116)Xinjiang Uygur Autonomous Region Key Research and Development Program(Grant No.2022B01030)Shanghai Pujiang Program(Grant No.21PJD019)。
文摘Lightweight and high-toughness carbon fiber/phenolic ablator(CFPA)is required as the Thermal Protection System(TPS)material of aerospace vehicles for next-generation space missions.To improve the ablative properties,silica sol with good particle size distribution prepared using tetramethoxysilane(TMOS)was blended with natural rubber latex and deposited onto carbon fiber felt,which was then integrated with phenolic aerogel matrix,introducing nano-silica into the framework of CFPA.The modified CFPA with a low density of 0.28—0.31 g/cm3exhibits strain-in-fracture as high as 31.2%and thermal conductivity as low as 0.054 W/(m·K).Furthermore,a trace amount of nano-silica could effectively protect CFPA from erosion of oxidizing atmosphere in different high-temperature environments.The oxyacetylene ablation test of 3000°C for 20 s shows a mass ablation rate of 0.0225 g/s,a linear ablation rate of 0.209 mm/s for the modified CFPA,which are 9.64%and 24.82%lower than the unmodified one.Besides,the long-time butane ablation test of 1200°C for 200 s shows an insignificant recession with mass and linear ablation rate of 0.079 g/s and 0.039 mm/s,16.84%and 13.33%lower than the unmodified one.Meanwhile,the fixed thermocouple in the test also demonstrates a good thermal insulation performance with a low peak back-face temperature of 207.7°C,12.25%lower than the unmodified one.Therefore,the nano-silica modified CFPA with excellent overall performance presents promising prospects in high-temperature aerospace applications.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11105013,11205017,and 11371065the National High-Tech R&D Program(863 Program) through Grant No.2012AA01A303
文摘The paper investigates theoretically the optimization of the doped ablator layers for the plastic ignition capsule. The high-resolved one-dimensional implosion simulations show that the inner pure CFI layer of the Si-doped design is excessively preheated by the hard x-ray, leading to the unstable ablator-fuel interface compared to the Ge-doped capsule. This is because that the Si K-shell absorption edge （1.8 keV） is higher than the Ge L-edge （1.3 keV）, and Si dopant makes more hard x-ray penetrate through the doped ablator layers to preheat the inner pure CH layer. So an optimization of the doped ablator layers （called ＂Si/Ge capsule＂） is performed： an Si-doped CH layer is placed next to the outer pure CH layer to keep the high implosion velocity; next to the Si-doped layer is a thin Ge-doped layer, in order to absorb the hard x-ray and protect the inner undoped CH-layer from excessively preheating. The simulations show that the Si/Ge capsule can effectively improve hydrodynamic stability at the ablator-fuel interface while keeping the high implosion velocity.
基金Supported by the National Key Research and Development Program,No.2023YFF0713700 and No.2023YFF0713705Common Technology R&D Platform of Shaanxi Province,No.2023GXJS-01-1-2the Cyrus Tang Foundation Chung Ying Young Scholars Program.
文摘BACKGROUND Duodenal mucosal ablation(DMA)using irreversible electroporation(IRE)with a glucagon-like peptide-1 receptor agonist has been clinically shown to reduce liver lipid deposition in non-alcoholic fatty liver disease(NAFLD).However,the specific metabolic contributions of DMA using IRE in NAFLD remain unclear.AIM To assess the feasibility and effectiveness of DMA using IRE in NAFLD rat models.METHODS Seven-week-old male Sprague-Dawley rats underwent DMA using IRE after 8 weeks on a high-fat diet.Two weeks post-treatment,duodenal and liver tissues and blood samples were collected.We evaluated differences in the duodenal wall structure,liver lipid deposition,enteroendocrine,claudin,and zonula ocludens-1 in the duodenal mucosa.RESULTS DMA using IRE could be safely performed in rats with NAFLD without duodenal bleeding,perforation,or stenosis.The duodenum healed well 2 weeks after DMA and was characterized by slimmer villi,narrower and shallower crypts,and thicker myenterons compared with the sham-control setting.Liver lipid deposition was reduced and serum lipid index parameters were considerably improved in the DMA setting.However,these improvements were independent of food intake and weight loss.In addition,enteroendocrine parameters,such as claudin,and zonula ocludens-1 levels in the duodenal mucosa,differed between the different settings in the DMA group.CONCLUSION By altering enteroendocrine and duodenal permeability,simple DMA using IRE ameliorated liver lipid deposition and improved serum lipid parameters in NAFLD rats.
基金supported by the National Key R&D Pro-gram of China(Grant No.2021YFA0715803)the National Natural Science Foundation of China(Grant Nos.52293373,52130205,and 52302091)+1 种基金the Joint Fund of Henan Province Science and Technol-ogy R&D Program(No.225200810002)the ND Basic Research Funds of Northwestern Polytechnical University(No.G2022WD).
文摘Multicomponent(Hf-Zr-Ta)B_(2)potentially provides improved ablation resistance compared with silicon-based ceramics.Here we deposited(Hf_(0.5-x/2)Zr_(0.5-x/2)Ta_(x))B_(2)(x=0,0.1,and 0.2)coatings onto C/C com-posites,and investigated their ablation behaviors under an oxyacetylene torch with a heat flux of 2.4 MW m^(-2).It was observed that the x=0.1 oxide scale bulged but was denser,and the x=0.2 oxide scale was blown away due to the formation of excessive liquid.Based on these findings,we further de-veloped a duplex(Hf-Zr-Ta)B_(2)coating that showed a linear recession rate close to zero(0.11μm s^(-1))after two 120-s ablation cycles.It is identified that the resulting oxide scale is mainly composed of(Hf,Zr)_(6)Ta_(2)O_(17)and(Hf,Zr,Ta)O_(2)by performing aberration-corrected(scanning)transmission electron microscopy.The protective mechanism is related to the peritectic transformation of orthorhombic-(Hf,Zr)_(6)Ta_(2)O_(17)to tetragonal-(Hf,Zr,Ta)O_(2)plus Ta-dominated liquid.This study contributes to the develop-ment of Ta-containing multicomponent UHTC bulk and coatings for ultra-high temperature applications.
基金supported by the National Natural Science Foundation of China(Nos.U2241240,12172045 and 12221002)the Opening Fund of State Key Laboratory of Explosion Science and Technology of Beijing Institute of Technology,China(No.ZDKT23-02)。
文摘Carbon Carbon(C/C)composites in thermal-protection system are exposed to severe thermochemical ablation and mechanical erosion,and their thermal-protection performance is of vital importance to the structural safety and flight status of hypersonic vehicles.We numerically analyzes the mesoscopic ablation-erosion of C/C Composites with Inclined Fibers(CCIF).First,a thermochemical ablation model describing the reaction-diffusion coupled problem of C/C composites on mesoscale is employed to analyze ablative process,and the corresponding surface ablation morphology is obtained.Then,the ablation morphology of CCIF is taken as the geometrical model for mechanical erosion analysis,and their damage and failure behavior under high-speed airflow shear is analyzed by using progressive damage method.Moreover,the effects of fiber inclined angle and airflow direction on the mechanical erosion of CCIF are investigated,and the ablationerosion behavior is analyzed and discussed.The results show that the failure modes of mechanical erosion in inner and edge regions are obviously different,showing granular and block erosion phenomena respectively.The mechanical erosion of CCIF in the direction of reverse flow is easier than that in the direction of forward flow.These results can provide a theoretical basis for the design and optimization of thermal protection system materials.
文摘The ablative material is supposed to be one of good candidates for LRE （liquid rocket engine） combustion chamber to achieve both high reliability and low cost and a numerical analysis for the ablator is considered to be a potentially efficient tool to reduce cost as well. So far, ablators have been successfully applied for many SRM （solid rocket motors）, but the application to LRE is still quite limited in Japan. The authors believe that this is primarily because of the unpredictable nature of the heat load from combustion gases to the combustor wall. Indeed, reliable thermal design of ablative combustion chamber, namely reliable prediction of thermal performance, needs both reliable heat load model and reliable ablator response model. This paper elaborates our research activities and our recent research findings.
文摘This editorial comments on a study by Zuo et al.The focus is on the efficacy of he-patic arterial infusion chemotherapy combined with camrelizumab and apatinib(the TRIPLET regimen),alongside microwave ablation therapy,in treating advanced hepatocellular carcinoma(HCC).The potential application of this combination therapy for patients with advanced HCC is evaluated.
文摘Objective: To assess the predictors of successful inactivation of benign thyroid nodules using radiofrequency ablation (RFA) and the hormonal responses thereafter. Methods: A retrospective study conducted at Zhongnan Hospital of Wuhan University (January 2022 to January 2024) analysed thyroid tumor characteristics using B-mode ultrasound, colour Doppler imaging, and CEUS post-RFA. Thyroid hormone levels were also assessed before RFA and at 1, 3, and 6 months after the procedure. Results: The study involved 72 patients with benign thyroid nodules, comprising 13 males and 59 females, with a mean age of 45.8 ± 12.1 years. Complete inactivation was achieved in 70.8% of nodules, while 29.2% showed partial inactivation. Nodules with complete inactivation exhibited more calcification (p = 0.040), whereas those with partial inactivation demonstrated higher vascularity (p Conclusion: In conclusion, this study found that therapeutic RFA effectively achieves high rates of complete inactivation in benign thyroid nodules, with the degree of inactivation mainly influenced by nodule vascularity and calcifications.
文摘Ultrasound-guided percutaneous thermal ablation has gained popularity as treatment for malignant hepatic tumors.It was first introduced as ablation therapy for hepatocellular carcinoma and cirrhosis comorbidity.Recently,this technique has also been used in the treatment of intrahepatic cholangiocarcinoma for patients who are not eligible for surgical resection.There are several types of thermal ablation techniques.Radiofrequency ablation and microwave ablation are two common methods that induce necrosis of the lesions.Irreversible electroporation is a relatively new non-thermal technique and is suitable in cases where thermal ablation would be ineffective or dangerous(e.g.,malignant tumors close to vascular or biliary structures).Irreversible electroporation can induce tumoral necrosis without damage to vascular and biliary structures.The aim of this minireview was to describe the safety,efficacy,and clinical indications of these techniques in the treatment of patients with intrahepatic cholangiocarcinoma who are ineligible for surgery.
文摘BACKGROUND Atrial fibrillation,affecting approximately 33 million people globally,is the most common sustained arrhythmia,increasing risks of stroke,heart failure,and mortality.Pulmonary vein isolation via catheter ablation is a key rhythm control strategy,with cryoballoon ablation(CBA)being a standard thermal method but associated with risks like phrenic nerve palsy(5%-10%),esophageal injury,and vein stenosis.Pulsed field ablation(PFA),a non-thermal technique using electrical pulses for selective electroporation,offers potential for shorter procedures and improved safety.Limited direct comparisons between PFA and CBA necessitate a systematic evaluation of their efficacy and safety.AIM To compare the procedural success,safety,and 1-year arrhythmia-free survival of PFA vs CBA for first-time pulmonary vein isolation in adults with paroxysmal or persistent atrial fibrillation.METHODS A Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review and metaanalysis was conducted,searching PubMed,EMBASE,Web of Science,and other databases up to August 2025 for comparative studies.Pooled mean difference for continuous outcomes and odds ratio(OR)for dichotomous outcomes were calculated using random-effects models.Study quality was assessed with the Newcastle-Ottawa Scale,heterogeneity with I2,and publication bias with funnel plots.RESULTS Seven studies(six cohorts,one randomized controlled trial)were included,with a mean age of approximately 66 years,59%-78%male,and high prevalence of hypertension and diabetes.PFA significantly reduced procedure time(mean difference=-15.24 minutes,95%CI:-16.63 to-13.85,P<0.00001;I2=89%),improved arrhythmia-free survival(OR=1.27,95%CI:1.04-1.55,P=0.02;I2=45%),and lowered phrenic nerve palsy risk(OR=0.17,95%CI:0.04-0.63,P=0.008;I2=0%).No significant differences were found in fluoroscopy time,cardiac tamponade,repeat ablation,or vascular complications.CONCLUSION PFA demonstrates shorter procedure times,reduced phrenic nerve palsy,and better arrhythmia control compared to CBA,with comparable safety profiles.However,evidence is limited by observational study designs,heterogeneity,and potential bias.Large-scale randomized controlled trials with extended follow-up are needed to confirm these findings and guide clinical practice.
基金Open Fund of Zhijian Laboratory,Rocket Force University of Engineering(2024-ZJSYS-KF02-09)National Natural Science Foundation of China(51902028,52272034)+1 种基金Key Research and Development Program of Shaanxi(2023JBGS-15)Fundamental Research Funds for the Central Universities(Changan University,300102313202,300102312406)。
文摘To improve the compactness and properties of C/C-SiC-ZrC composites produced by precursor infiltration and pyrolysis(PIP)method,the low-temperature reactive melt infiltration(RMI)process was used to seal the composites using Zr_(2)Cu as the filler.The microstructure,mechanical properties,and ablation properties of the Zr_(2)Cu packed composites were analyzed.Results show that during Zr_(2)Cu impregnation,the melt efficiently fills the large pores of the composites and is converted to ZrCu due to a partial reaction of zirconium with carbon.This results in an increase in composite density from 1.91 g/cm^(3)to 2.24 g/cm^(3)and a reduction in open porosity by 27.35%.Additionally,the flexural strength of Zr_(2)Cu packed C/C-SiC-ZrC composites is improved from 122.78±8.09 MPa to 135.53±5.40 MPa.After plasma ablation for 20 s,the modified composites demonstrate superior ablative resistance compared to PIP C/C-SiC-ZrC,with mass ablation and linear ablation rates of 2.77×10^(−3)g/s and 2.60×10^(−3)mm/s,respectively.The“selftranspiration”effect of the low-melting point copper-containing phase absorbs the heat of the plasma flame,further reducing the ablation temperature and promoting the formation of refined ZrO_(2)particles within the SiO_(2)melting layer.This provides more stable erosion protection for Zr_(2)Cu packed C/C-SiC-ZrC composites.
基金Supported by the Joint Medical Scientific Research Project of Chongqing Science and Technology Committee and Chongqing Health Committee,No.2021MSXM308.
文摘Microwave ablation(MWA)is emerging as a highly effective treatment for colorectal liver metastases(CRLMs).This review explores the advantages of MWA compared to other ablative techniques such as radiofrequency ablation and cryoablation and highlights its clinical efficacy,safety,and technical considerations.MWA offers significant benefits,including higher intratumoral temperatures,larger ablation zones,and reduced susceptibility to the heat-sink effect,which make it particularly suitable for tumors near large blood vessels.This review details the patient selection criteria,procedural approaches,and the use of advanced imaging techniques to improve the precision and effectiveness of MWA.Clinical outcomes indicate that MWA achieves high rates of complete tumor ablation and long-term survival with a favorable safety profile.This review is significant because it provides updated insights into the expanding role of MWA in treating unresectable CRLM and its potential as an alternative to surgical resection for resectable tumors.By summarizing recent studies and clinical trials,this review highlights the comparative effectiveness,safety,and integration with systemic therapies of MWA.In conclusion,MWA is a promising treatment option for CRLM and offers outcomes comparable to or better than those of other ablative techniques.Future research should focus on optimizing technical parameters,integrating MWA with systemic therapies,and conducting large-scale randomized controlled trials to establish standardized treatment protocols.Advancing our understanding of MWA will enhance its application and improve long-term survival and quality of life for patients with CRLM.
基金supported by the 2024 University Scientific Research Project of Guangzhou Education Bureau(Project No.24312286Certificate No.gd20249983112).
文摘Objective: To evaluate the efficacy of endovenous radiofrequency ablation (RFA) and laser ablation (EVLA) in the treatment of superficial varicose veins of the lower extremities. Methods: Seventy-eight patients with superficial varicose veins treated at a hospital between April 2022 and May 2023 were selected and divided into a radiofrequency ablation group (RFA group;39 cases) and a laser ablation group (EVLA group;39 cases) based on the treatment method. Operation time, postoperative recovery duration, venous clinical severity score (VCSS) changes, complication rates, closure rates, and recurrence rates were compared between the groups at 1 month, 3 months, and 12 months postoperatively. The postoperative therapeutic outcomes were comprehensively evaluated. Results: No significant differences in age, gender, disease grade, or disease course were observed between the groups (P > 0.05). The superficial varicose vein closure rate was 100% in both groups at 1 and 3 months postoperatively. At 12 months, the closure rate was 94.87% in the RFA group and 97.43% in the EVLA group, with no statistically significant difference (P > 0.05). No significant differences were observed in VCSS changes or complication incidence between the groups (P > 0.05). Conclusion: Radiofrequency ablation and laser ablation demonstrate comparable efficacy and safety in the treatment of superficial varicose veins of the lower extremities.
基金supported by the Key Program of the National Natural Science Foundation of China(No.52032003)the Major Program of the National Natural Science Foundation of China(No.52293372)+2 种基金the National Natural Science Foundation of China(No.51972082)the National Natural Science Foundation of China(No.52102093)the National Natural Science Foundation of China(No.52172041)and the science foundation of national key laboratory of science and technology on advanced composites in special environments.
文摘The current generation of ultrahigh temperature ceramic precursors typically encounters obstacles in achieving high ceramic yields(<40 wt.%)due to the challenges in integrating significant amounts of boron,which hampers their conversion into boride-based ultrahigh temperature ceramics.To tackle these challenges,a serious of pioneering liquid multi-component hafnium-containing ceramic SiHfCB precursors(with different Hf/Si ratios)have been developed.These novel precursors are featured with stable molec-ular structure and high ceramic yield which were successfully created through a novel one-pot polymer-ization process.They present in liquid form and their structure is characterized by C-C bonds forming its main chain with branched chains of O-Si-O,Si-O-Hf,Si-O-B,and B-O-Hf which have untapped advantages including uniform component dispersion,and excellent fluidity.The ceramic yield of SiHfCB precursor with Hf/Si of 0.2 is remarkably up to 68.6 wt.%at 1500℃,and their Hf content exceeded 50 wt.%.Of particular interest,the pyrolyzed product HfB_(2)-SiC nanopowders derived from the SiHfCB precursor with Hf/Si of 0.2,consist of nanopowders in the 40-60 nm range with a density of 5.23 g cm^(−3).Remarkably,this material demonstrates exceptional performance in ultrahigh temperature oxygen-containing environ-ments at 2500℃,showing near-zero ablation with a linear ablation rate of just 2.5×10^(−4) mm s^(−1).Post-ablation analysis of the microstructure reveals that the formation of a lava-like HfO_(2) and HfO_(2)-SiO_(2) oxide layer effectively blocks oxygen penetration and provides excellent oxidation resistance.The inno-vative SiHfCB hafnium-containing ceramic precursor offers a groundbreaking solution for the preparation of lightweight ultrahigh-temperature ceramics.This development is poised to provide robust technical support for the use of ultrahigh temperature ceramics in non-ablative thermal protective systems,partic-ularly in the construction of hypersonic vehicles,where ultrahigh temperature resilience is crucial.
基金supported by the National Major Scientific Instruments and Equipment Development Project Funded by the National Natural Science Foundation of China(81827803)the Jiangsu Province Key Research and Development Program(Social Development)Project(BE2020705).
文摘Purpose:The major limitation of tumor microwave ablation(MWA)operation is the lack of predictability of the ablation zone before surgery.Operators rely on their individual experience to select a treatment plan,which is prone to either inadequate or excessive ablation.This paper aims to establish an ablation prediction model that guides MWA tumor surgical planning.Methods:An MWA process was first simulated by incorporating electromagnetic radiation equations,thermal equations,and optimized biological tissue parameters(dynamic dielectric and thermophysical parameters).The temperature distributions(the short/long diameters,and the total volume of the ablation zone)were then generated and verified by 60 cases ex vivo porcine liver experiments.Subsequently,a series of data were obtained from the simulated temperature distributions and to further fit the novel ablation coagulated area prediction model(ACAPM),thus rendering the ablation-dose table for the guiding surgical plan.The MWA clinical patient data and clinical devices suggested data were used to validate the accuracy and practicability of the established predicted model.Results:The 60 cases ex vivo porcine liver experiments demonstrated the accuracy of the simulated temperature distributions.Compared to traditional simulation methods,our approach reduces the long-diameter error of the ablation zone from 1.1 cm to 0.29 cm,achieving a 74%reduction in error.Further,the clinical data including the patients'operation results and devices provided values were consistent well with our predicated data,indicating the great potential of ACAPM to assist preoperative planning.
