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
We conduct an experimental study supported by theoretical analysis of single laser ablating copper to investigate the interactions between laser and material at different sample temperatures,and predict the changes of...We conduct an experimental study supported by theoretical analysis of single laser ablating copper to investigate the interactions between laser and material at different sample temperatures,and predict the changes of ablation morphology and lattice temperature.For investigating the effect of sample temperature on femtosecond laser processing,we conduct experiments on and simulate the thermal behavior of femtosecond laser irradiating copper by using a two-temperature model.The simulation results show that both electron peak temperature and the relaxation time needed to reach equilibrium increase as initial sample temperature rises.When the sample temperature rises from 300 K to 600 K,the maximum lattice temperature of the copper surface increases by about 6500 K under femtosecond laser irradiation,and the ablation depth increases by 20%.The simulated ablation depths follow the same general trend as the experimental values.This work provides some theoretical basis and technical support for developing femtosecond laser processing in the field of metal materials.展开更多
Pellet injection is a primary method for fueling the plasma in magnetic confinement devices.For that goal the knowledges of pellet ablation and deposition profiles are critical.In the present study,the pellet fueling ...Pellet injection is a primary method for fueling the plasma in magnetic confinement devices.For that goal the knowledges of pellet ablation and deposition profiles are critical.In the present study,the pellet fueling code HPI2 was used to predict the ablation and deposition profiles of deuterium pellets injected into a typical H-mode discharge on the EAST tokamak.Pellet ablation and deposition profiles were evaluated for various pellet injection locations,with the aim at optimizing the pellet injection to obtain a deep fueling depth.In this study,we investigate the effect of the injection angle on the deposition depth of the pellet at different velocities and sizes.The ablation and deposition of the injected pellet are mainly studied at each injection position for three different injection angles:0°,45°,and 60°.The pellet injection on the high field side(HFS)can achieve a more ideal deposition depth than on the low field side(LFS).Among these angles,horizontal injection on the middle plane is relatively better on either the HFS or the LFS.When the injection location is 0.468 m below the middle plane on the HFS or 0.40 m above the middle plane of the LFS,it can achieve a similar deposition depth to the one of its corresponding side.When the pre-cooling effect is taken into account,the deposition depth is predicted to increase only slightly when the pellet is launched from the HFS.The findings of this study will serve as a reference for the update of pellet injection systems for the EAST tokamak.展开更多
The micro-ablation processes and morphological evolution of ablative craters on single-crystal magnesium under subpicosecond laser irradiation are investigated using molecular dynamics(MD) simulations and experiments....The micro-ablation processes and morphological evolution of ablative craters on single-crystal magnesium under subpicosecond laser irradiation are investigated using molecular dynamics(MD) simulations and experiments.The simulation results exhibit that the main failure mode of single-crystal Mg film irradiated by a low fluence and long pulse width laser is the ejection of surface atoms,which has laser-induced high stress.However,under high fluence and short pulse width laser irradiation,the main damage mechanism is nucleation fracture caused by stress wave reflection and superposition at the bottom of the film.In addition,Mg[0001] has higher pressure sensitivity and is more prone to ablation than Mg[0001].The evolution equation of crater depth is established using multi-pulse laser ablation simulation and verified by experiments.The results show that,under multiple pulsed laser irradiation,not only does the crater depth increase linearly with the pulse number,but also the quadratic term and constant term of the fitted crater profile curve increase linearly.展开更多
GHz burst-mode femtosecond(fs)laser,which emits a series of pulse trains with extremely short intervals of several hundred picoseconds,provides distinct characteristics in materials processing as compared with the con...GHz burst-mode femtosecond(fs)laser,which emits a series of pulse trains with extremely short intervals of several hundred picoseconds,provides distinct characteristics in materials processing as compared with the conventional irradiation scheme of fs laser(single-pulse mode).In this paper,we take advantage of the moderate pulse interval of 205 ps(4.88 GHz)in the burst pulse for high-quality and high-efficiency micromachining of single crystalline sapphire by laser induced plasma assisted ablation(LIPAA).Specifically,the preceding pulses in the burst generate plasma by ablation of copper placed behind the sapphire substrate,which interacts with the subsequent pulses to induce ablation at the rear surface of sapphire substrates.As a result,not only the ablation quality but also the ablation efficiency and the fabrication resolution are greatly improved compared to the other schemes including single-pulse mode fs laser direct ablation,single-pulse mode fs-LIPAA,and nanosecond-LIPAA.展开更多
A controlled model of thermal shield of ablation with trapspiration cooling is develoed. The existence and uniqueness of the classical solution can be obtained by Friedman and Jiang's methods. The positivity of th...A controlled model of thermal shield of ablation with trapspiration cooling is develoed. The existence and uniqueness of the classical solution can be obtained by Friedman and Jiang's methods. The positivity of the solution is proved and the conditions for the coolant flux under which the abladtion process will complete in finite time are also determined. Finally, we show the existence of critical coolant flux beyond which the ablation material begin melting.展开更多
Background Although elderly patients have been included in published series of catheter ablation for atrial fibrillation （AF）, clinicalbenefit and safety remain still less defined in this population. A retrospective...Background Although elderly patients have been included in published series of catheter ablation for atrial fibrillation （AF）, clinicalbenefit and safety remain still less defined in this population. A retrospective analysis of the results of catheter ablation for AF in a large volumecenter focused on comparison of elderly patients with the rest of the patient cohort was conducted in this study. Methods Consecutive patientswho underwent catheter ablation for AF between January 2001 and December 2016 were analysed. A total population of 3197 patients wasdichotomized by the age of 70 years （394 elderly vs. 2803 younger subjects）. Patients were followed in terms of arrhythmia status and sur-vival for a median period of 18 vs. 21 and 35 vs. 57 months, respectively. Results Elderly patients were more frequently females （49% vs.29%, P 〈 0.0001）, had a history of hypertension （79% vs. 57%, P 〈 0.0001）, diabetes （16% vs. 11%, P 〈 0.01）, stroke （9% vs. 6%, P 〈 0.01）,coronary/peripheral artery disease （14% vs. 8%, P 〈 0.0001）, and CHAzDS2-VASc score （3.1 ± 1.3 vs. 1.5 ± 1.2 s, P 〈 0.0001）. Major com-plications were more frequent in elderly （5.3% vs. 3.2%, P = 0.03）; however, this difference was driven by vascular complications （3.6% vs.1.9%, P = 0.04）. There were comparable rates of cerebrovascular （0.3 vs. 0.3%） or nonvascular complications （1.8 vs. 1.2%）. Good arrhyth-mia control was inferior in elderly patients as compared with the rest of the cohort, both without and with antiarrhythmic drugs： 44.2% vs.58.2% （P 〈 0.0001） and 78.2 vs. 83.2% （P 〈 0.01）, respectively. Poor arrhythmia control was associated with relative risk of all-cause mor-tality of 2.7 （95% CI： 1.1-6.4） in elderly patients and 1.4 （95% CI： 0.9-2.0） in younger subjects. Conclusions Catheter ablation for AF inelderly patients is safe although somewhat less effective. Good arrhythmia control is associated with better survival, especially in elderly patients.展开更多
Background Prevalence of atrial fibrillation （AF） increases with age. Radiofrequency catheter ablation （RFCA） is an establishedtreatment option superior to antiarrhythmics （AAs）. In this study, we investigated s...Background Prevalence of atrial fibrillation （AF） increases with age. Radiofrequency catheter ablation （RFCA） is an establishedtreatment option superior to antiarrhythmics （AAs）. In this study, we investigated safety and efficacy of RFCA of AF in octogenarians.Methods From our database, we extracted procedural and follow-up data for patients 〉 80 years with symptomatic AF undergoing RFCAand compared this population to RFCA patients 〈 50 years. All patients underwent pulmonary vein isolation （PVI） supplemented by linearlesions in PVI-nonresponders. Arrhythmia-free survival was assessed using seven day Holter every three months post procedure. All patientscompleted their 12 months follow-up. Results Fifty patients aged ≥80 years （80.5 ± 1.6 years） were compared to 259 patients aged 〈 50years （43.5±5.5 years）. The RFCA complication rate did not vary between groups. No differences in procedural characteristics were seenafter being analyzed by type of AF. Among patients with paroxysmal AF, 71.4% octogenarian vs. 84.7% young patients was free of anyarrhythmia, without AAs, after single procedure. For non-paroxysmal AF, arrhythmia-free survival without AAs, was considerably lower（58.6% octogenarians vs. 81.2% younger patients, P = 0.023）. If AAs were used, arrhythmia-free survival for paroxysmal AF increased to90.5% and 92.1% in octogenarians and younger patients, respectively; and in non-paroxysmal AF it increased to 79.3% vs. 88.4%. ConclusionsRFCA is a safe and effective strategy to achieve normal sinus rhythm in a highly selected group of octogenarians. Paroxysmal AF ablation inoctogenarians has similar clinical effectiveness as that seen in much younger patients. Non-paroxysmal AF ablation has lower, but still rea-sonable clinical effectiveness.展开更多
Compared with direct ablation, confined ablation provides an effective way to obtain a large target momentum and a high coupling coefficient. By using a transparent glass layer to cover the target surface, the couplin...Compared with direct ablation, confined ablation provides an effective way to obtain a large target momentum and a high coupling coefficient. By using a transparent glass layer to cover the target surface, the coupling coefficient is enhanced by an order of magnitude. With the increase of the gap width between the target surface and the cover layer, the coupling coefficient exponentially decreases. It is found that the coupling coefficient is also related to the thickness of the cover layer.展开更多
Backgound Red cell distribution width(RDW) and neutrophil-to-lymphocyte ratio(NLR) are simple hematologic indices that have been used to predict adverse outcomes in different clinical settings. The aim of our study is...Backgound Red cell distribution width(RDW) and neutrophil-to-lymphocyte ratio(NLR) are simple hematologic indices that have been used to predict adverse outcomes in different clinical settings. The aim of our study is to determine whether RDW and NLR can predict atrial fibrillation(AF) recurrence in patients undergoing AF ablation. Methods Consecutive patients, without known hematological disorders, who underwent AF catheter ablation between January 2014 and April 2017 were enrolled into this study. Blood samples were taken one day before and five hours after the ablation procedure. Results A total of 346 patients(224 males(65%), mean age: 59 ± 11 years old) were included. After a mean follow up of 26.2 ± 12.1 months, 80(23.1%) patients experienced late AF recurrence(defined as any recurrence after the blanking period of three months), while 97(28%) patients experienced early AF recurrence during the blanking period. Univariate analysis showed that early arrhythmia recurrence, type of AF and NLR after the procedure were significantly associated with late AF recurrence, while early arrhythmia recurrence and NLR remained significant in multivariate analysis. RDW was not associated with late AF recurrence. None of the parameters above predicted early arrhythmia recurrence. Conclusions Simple and inexpensive hematological indices such as NLR should be evaluated for their ability to predict AF recurrence in patients undergoing catheter ablation in larger prospective studies.展开更多
Orientations of laser induced periodic surface structures(LIPSS)are usually considered to be governed by the laser polarization state.In this work,we unveil that fluid dynamics induced by femtosecond(fs)laser ablation...Orientations of laser induced periodic surface structures(LIPSS)are usually considered to be governed by the laser polarization state.In this work,we unveil that fluid dynamics induced by femtosecond(fs)laser ablation in liquid(fs-LAL)can easily break this polarization restriction to produce irregular circular-LIPSS(CLIPPS)and crisscross-LIPSS(CCLIPSS).Fs laser ablation of silicon in water shows formation of diverse LIPSS depending on ablation conditions.At a high power of 700 mW(repetition rate of 100 kHz,pulse duration of 457 fs and wavelength of 1045 nm),single/twin CLIPSS are produced at the bottom of macropores of several microns in diameter due to the formation of strong liquid vortexes and occurrence of the vortex shedding effect.Theoretical simulations validate our speculation about the formation of liquid vortex with an ultrahigh static pressure,which can induce the microstructure trenches and cracks at the sidewalls for fs-LAL of Si and tungsten(W)in water,respectively.At a low power of 50 mW,weak liquid vortexes are produced,which only give birth to curved LIPSS in the valleys of grooves.Consequently,it is deduced that liquid vortex plays a crucial role in the formation of macropores.Mountain-like microstructures induce complex fluid dynamics which can cause the formation of CCLIPSS on them.It is believed that liquid vortexes and fluid dynamics presented in this work open up new possibilities to diversify the morphologies of LIPSS formed by fs-LAL.展开更多
Background Atrial fibrillation （AF） catheter ablation has emerged as a promising treatment strategy for AF, but has not been widely adopted in the elderly population. The present study aimed to determine the safety ...Background Atrial fibrillation （AF） catheter ablation has emerged as a promising treatment strategy for AF, but has not been widely adopted in the elderly population. The present study aimed to determine the safety and efficacy of AF catheter ablation in the elderly popula-tion. Methods and Results The study population consisted of 316 patients with paroxysmal AF who underwent left atrial ablation. Ninety-five patients were≥65 years （48 males, mean age 68.9 ± 3.0 years old） and 221 patients were〈65 years old （130 males, mean age 52.5 ± 10.4 years old）. After a mean follow-up period of 34.0 ± 15.1 months, 55 （57.9%） patients in the elderly group were free from ar-rhythmia recurrence compared with 149 （67.4%） patients in the younger group （P=0.169）. Procedural complications were uncommon in both study groups. In logistic regression analysis, left atrial diameter （P=0.003）, hypertension （P=0.001）, dyslipidemia （P=0.039）, and coronary artery disease （P=0.018） were independent predictors of AF recurrence in the elderly population. Conclusions Catheter ablation of AF is safe and effective in older patients. Invasive strategies should be considered as an alternative choice in symptomatic elderly patients with AF.展开更多
Background The long-term prognostic influence of left atrial diameter （LAD） remodeling on the status of post-radiofrequency catheter ablation （RI CA） atrial fibrillation （AF） is unclear. This study employed a tw...Background The long-term prognostic influence of left atrial diameter （LAD） remodeling on the status of post-radiofrequency catheter ablation （RI CA） atrial fibrillation （AF） is unclear. This study employed a two-stage model from 3-year echocardiographic data to ascertain whether the two-stage model predicts RFCA outcome more favorably than models using the baseline LAD. Methods Data were retrospectively collected from 263 consecutive patients with drug-refractory AF undergoing RFCA. Regular echocardiographic measurements of LAD were performed at baseline, 1, 3, 6, and 12 months and then every 6 months after RFCA. Sex, age, type of AF, number of RFCA, and AF status were recorded. We obtain the actual （predicted） 3-year LAD using a longitudinal linear mixed model （1st stage）. Logistic regression models based on the baseline LAD （Model 1）, actual （predicted） 3-year LAD （Model 2） （2nd stage）, and observed 3-year LAD （Model 3） were constructed to predict RFCA outcome. The area under the receiver operating characteristic curve （AUC） were used to assess the performance of models. Results The lowess smoothed curve indicated that the LAD declined over the first three months and remained stable up to 36 months after RFCA. The degree of LAD reduction was significantly influenced by the baseline LAD. Non-paroxysmal AF, large LAD and female gender were significant predictors of AF recurrence. Model 2 had the largest AUC among the three models. Conclusions This longitudinal study-based two-stage model outperforms the original logistic model using the baseline LAD. Non-paroxysmal AF, larger LAD and female gender are significant predictors of RFCA failure.展开更多
Background It is unclear whether catheter ablation(CA)for atrial fibrillation(AF)affects the long-term prognosis in the elderly.This study aims to evaluate the relationship between CA and long-term outcomes in elderly...Background It is unclear whether catheter ablation(CA)for atrial fibrillation(AF)affects the long-term prognosis in the elderly.This study aims to evaluate the relationship between CA and long-term outcomes in elderly patients with AF.Methods Patients more than 75 years old with non-valvular AF were prospectively enrolled between August 2011 and December 2017 in the Chinese Atrial Fibrillation Registry Study.Participants who underwent CA at baseline were propensity score matched(1:1)with those who did not receive CA.The outcome events included all-cause mortality,cardiovascular mortality,stroke/transient ischemic attack(TIA),and cardiovascular hospitalization.Results Overall,this cohort included 571 ablated patients and 571 non-ablated patients with similar characteristics on 18 dimensions.During a mean follow-up of 39.75±19.98 months(minimum six months),24 patients died in the ablation group,compared with 60 deaths in the non-ablation group[hazard ratio(HR)=0.49,95%confidence interval(CI):0.30-0.79,P=0.0024].Besides,6 ablated and 29 non-ablated subjects died of cardiovascular disease(HR=0.25,95%CI:0.11-0.61,P=0.0022).A total of 27 ablated and 40 non-ablated patients suffered stroke/TIA(HR=0.79,95%CI:0.48-1.28,P=0.3431).In addition,140 ablated and 194 non-ablated participants suffered cardiovascular hospitalization(HR=0.84,95%CI:0.67-1.04,P=0.1084).Subgroup analyses according to gender,type of AF,time since onset of AF,and anticoagulants exposure in initiation did not show significant heterogeneity.Conclusions In elderly patients with AF,CA may be associated with a lower incidence of all-cause and cardiovascular mortality.展开更多
High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or micro...High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or microgrooves at relatively higher fluences above 1 J/cm^2.This work aims to enrich the variety of HSFLs-containing hierarchical microstructures,by femtosecond laser(pulse duration:457 fs,wavelength:1045 nm,and repetition rate:100 kHz)in liquids(water and acetone)at laser fluence of 1.7 J/cm^2.The period of Si-HSFLs in the range of 110–200 nm is independent of the scanning speeds(0.1,0.5,1 and 2 mm/s),line intervals(5,15 and 20μm)of scanning lines and scanning directions(perpendicular or parallel to light polarization direction).It is interestingly found that besides normal HSFLs whose orientations are perpendicular to the direction of light polarization,both clockwise or anticlockwise randomly tilted HSFLs with a maximal deviation angle of 50°as compared to those of normal HSFLSs are found on the microstructures with height gradients.Raman spectra and SEM characterization jointly clarify that surface melting and nanocapillary waves play important roles in the formation of Si-HSFLs.The fact that no HSFLs are produced by laser ablation in air indicates that moderate melting facilitated with ultrafast liquid cooling is beneficial for the formation of HSFLs by LALs.On the basis of our findings and previous reports,a synergistic formation mechanism for HSFLs at high fluence was proposed and discussed,including thermal melting with the concomitance of ultrafast cooling in liquids,transformation of the molten layers into ripples and nanotips by surface plasmon polaritons(SPP)and second-harmonic generation(SHG),and modulation of Si-HSFLs direction by both nanocapillary waves and the localized electric field coming from the excited large Si particles.展开更多
Objectives To address whether menopause affects outcome of catheter ablation （CA） for atrial fibrillation （AF） by comparing the safety and long-term outcome of a single-procedure in pre-and post-menopausal women. ...Objectives To address whether menopause affects outcome of catheter ablation （CA） for atrial fibrillation （AF） by comparing the safety and long-term outcome of a single-procedure in pre-and post-menopausal women. Methods A total of 743 female patients who underwent a single CA procedure of drug-refractory AF were retrospectively analyzed. The differences in clinical presentation and outcomes of CA for AF between the pre-menopausal women （PreM group, 94 patients, 12.7%） and the post-menopausal women （PostM group, 649 patients, 87.3%） were assessed. Results The patients in the PreM group were younger （P＆lt;0.001） and less likely to have hypertension （P＆lt;0.001） and diabetes （P=0.005） than those in the PostM group. The two groups were similar with regards to the proportion of concomitant mitral valve regurgitation coronary artery disease, left atrium dimensions, and left ventricular ejection fraction. The overall rate of complica-tions related to AF ablation was similar in both groups （P=0.385）. After 43 （16-108） months of follow-up, the success rate of ablation was 54.3%in the PreM group and 54.2%in the PostM group （P=0.842）. The overall freedom from atrial tachyarrhythmia recurrence was simi-lar in both groups. Menopause was not found to be an independent predictive factor of the recurrence of atrial tachyarrhythmia. Conclusions The long-term outcomes of single-procedure CA for AF are similar in pre-and post-menopausal women. Results indicated that CA of AF appears to be as safe and effective in pre-menopausal women as in post-menopausal women.展开更多
Backgroud Recent studies have demonstrated that cystatin C is a valuable risk marker for cardiovascular disease morbidity and mortality.Therefore,we hypothesized that the pre-ablation cystatin C level was associated w...Backgroud Recent studies have demonstrated that cystatin C is a valuable risk marker for cardiovascular disease morbidity and mortality.Therefore,we hypothesized that the pre-ablation cystatin C level was associated with post-ablation atrial fibrillation(AF)recurrence.Methods 207 patients were enrolled and completed in this prospective observational study.Patients with AF scheduled for receive radiofrequency catheter ablation(RFCA)therapy were screened for the study.Before ablation therapy,electrocardiogram,24 h holter monitor,transesophageal echocardiography,serum cystatin C,high-sensitivity C-reactive protein,creatinine levels,and routine blood examinations were examined.After ablation,patients were followed up every week for the first month,and then at 2,3,6,9,and 12 months.Thereafter,patients came back to out-patient clinic every six months regularly.Electrocardiogram or 24 h holter monitor were repeated if the patient experienced palpitations or every six months.AF recurrence was defined as atrial flbrillation/atrial flutter or atrial tachycardia lasting≥30 seconds within three months after therapy.Results Compared to patients with no AF recurrence,patients with recurrence had longer AF history(P=0.007),more early recurrence(P=0.000),a larger left atrium(P=0.004),and higher pre-ablation cystatin C levels(P=0.000).Multivariate regression analysis revealed that cystatin C and left atria(LA)diameter were risk factors for AF recurrence.After adjusting for LA diameter,the risk of AF recurrence increased 30%with every milligram cystatin C elevation(95%CI:1.117-1.523).Conclusions Pre-ablation cystatin C levels were associated with AF recurrence after RFCA therapy,an optimal cut-off value of 1.190 mg/L(sensitivity=0.576;specificity=0.851).展开更多
Understanding shielding cross-effects is a prerequisite for maximal power-specific nanosecond laser ablation in liquids(LAL).However,discrimination between cavitation bubble(CB),nanoparticle(NP),and shielding,e.g.,by ...Understanding shielding cross-effects is a prerequisite for maximal power-specific nanosecond laser ablation in liquids(LAL).However,discrimination between cavitation bubble(CB),nanoparticle(NP),and shielding,e.g.,by the plasma or a transient vapor layer,is challenging.Therefore,CB imaging by shadowgraphy is performed to better understand the plasma and laser beam-NP interaction during LAL.By comparing the fluence-dependent CB volume for ablations performed with 1 ns pulses with reports from the literature,we find larger energy-specific CB volumes for 7 ns-ablation.The increased CB for laser ablation with higher ns pulse durations could be a first explanation of the efficiency decrease reported for these laser systems having higher pulse durations.Consequently,1 ns-LAL shows superior ablation efficiency.Moreover,a CB cascade occurs when the focal plane is shifted into the liquid.This effect is enhanced when NPs are present in the fluid.Even minute amounts of NPs trapped in a stationary layer decrease the laser energy significantly,even under liquid flow.However,this local concentration in the sticking film has so far not been considered.It presents an essential obstacle in high-yield LAL,shielding already the second laser pulse that arrives and presenting a source of satellite bubbles.Hence,measures to lower the NP concentration on the target must be investigated in the future.展开更多
Background Atrial fibrillation （AF） is the most frequent arrhythmia, and its prevalence is increasing with aging. We aimed to com-pare the long-term outcome data of patients 〈 65 years vs.≥ 65 years who underwent ...Background Atrial fibrillation （AF） is the most frequent arrhythmia, and its prevalence is increasing with aging. We aimed to com-pare the long-term outcome data of patients 〈 65 years vs.≥ 65 years who underwent catheter ablation （CA） for drug-refractory AF. MethodsConsecutive patients with primary pulmonary vein isolation performed between March 2001 and December 2011, and those who completeda five-year of follow-up were divided into two groups： patients aged 〈 65 years into group 1, and patients aged ≥ 65 into group 2. Long-termoutcome data concerning mortality, thromboembolic events （TE） and success rates were compared between these groups. Results A totalnumber of 390 patients were included, group 1 contained 310 patients, and 80 patients in group 2. In group 2, patients had more often impairedrenal function （P 〈 0.001） and thyroid disease （P = 0.047）. A total of fifteen patients died during the 6.63 ± 2.1 years of follow-up, with a sig-nificantly higher incidence in the older group （8/80 vs. 7/310 patients, P = 0.004）. The majority of fatal outcome was due to cancerous dis-eases in both groups. No difference was observed concerning the long-term TE rate （12/310 vs. 4/80 patients, P = 0.75）. Rhythm controlfailed in 25.9% of the patients, with no difference between the groups： 26.4% in group 1 vs. 23.7% in group 2 （P = 0,67）, ConclusionsDespite growing prevalence of AF in aging population, the elderly patients are underrepresented in CA procedures. Similar clinical successand TE complication rate are observed between the age-groups. Our data suggest more liberal criteria might be applied while selecting pa-tients for AF ablation.展开更多
The mechanical,thermal and ablation properties of carbon phenolic(C-Ph)composites(Type-I)reinforced with different weight percentages of organo-modified montmorillonite(o-MMT)nanoclay have been studied experimentally....The mechanical,thermal and ablation properties of carbon phenolic(C-Ph)composites(Type-I)reinforced with different weight percentages of organo-modified montmorillonite(o-MMT)nanoclay have been studied experimentally.Ball milling was used to disperse different weight(wt)percentages(0,1,2,4,6 wt.%)of nanoclay into phenolic resin.Viscosity changes to resin due to nanoclay was studied.On the other hand,nanoclay added phenolic matrix composites(Type-II)were prepared to study the dispersion of nanoclay in phenolic matrix by small angle X-ray scattering and thermal stability changes to the matrix by thermogravimetric analyser(TGA).This data was used to understand the mechanical,thermal and ablation properties of Type-I composites.Inter laminar shear strength(ILSS),flexural strength and flexural modulus of Type I composites increased by about 29%,12%and 7%respectively at2 wt.%addition of nanoclay beyond which these properties decreased.This was attributed to reduced fiber volume fraction(%Vf)of Type-I composites due to nanoclay addition at such high loadings.Mass ablation rate of Type-I composites was evaluated using oxy acetylene torch test at low heat flux(125 W/cm^(2))and high heat flux levels(500 W/cm^(2)).Mass ablation rates have increased at both flux levels marginally up to 2 wt.%addition of nanoclay beyond which it has increased significantly.This is in contrast to increased thermal stability observed for Type-I and Type-II composites up to 2 wt.%addition of nanoclay.Increased ablation rates due to nanoclay addition was attributed to higher insulation efficiency of nanolcay,which accumulates more heat energy in limited area behind the ablation front and self-propagating ablation mechanisms triggered by thermal decomposition of organic part of nanoclay.展开更多
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Project supported by the National Key Research and Development Program of China(Grant No.2019YFA0307701)the National Natural Science Foundation of China(Grant Nos.11674128,11674124,and 11974138).
文摘We conduct an experimental study supported by theoretical analysis of single laser ablating copper to investigate the interactions between laser and material at different sample temperatures,and predict the changes of ablation morphology and lattice temperature.For investigating the effect of sample temperature on femtosecond laser processing,we conduct experiments on and simulate the thermal behavior of femtosecond laser irradiating copper by using a two-temperature model.The simulation results show that both electron peak temperature and the relaxation time needed to reach equilibrium increase as initial sample temperature rises.When the sample temperature rises from 300 K to 600 K,the maximum lattice temperature of the copper surface increases by about 6500 K under femtosecond laser irradiation,and the ablation depth increases by 20%.The simulated ablation depths follow the same general trend as the experimental values.This work provides some theoretical basis and technical support for developing femtosecond laser processing in the field of metal materials.
基金supported by the National Natural Science Foundation of China (Grant Nos.12205196 and 12275040)the National Key Research and Development Program of China (Grant No.2022YFE03090003)。
文摘Pellet injection is a primary method for fueling the plasma in magnetic confinement devices.For that goal the knowledges of pellet ablation and deposition profiles are critical.In the present study,the pellet fueling code HPI2 was used to predict the ablation and deposition profiles of deuterium pellets injected into a typical H-mode discharge on the EAST tokamak.Pellet ablation and deposition profiles were evaluated for various pellet injection locations,with the aim at optimizing the pellet injection to obtain a deep fueling depth.In this study,we investigate the effect of the injection angle on the deposition depth of the pellet at different velocities and sizes.The ablation and deposition of the injected pellet are mainly studied at each injection position for three different injection angles:0°,45°,and 60°.The pellet injection on the high field side(HFS)can achieve a more ideal deposition depth than on the low field side(LFS).Among these angles,horizontal injection on the middle plane is relatively better on either the HFS or the LFS.When the injection location is 0.468 m below the middle plane on the HFS or 0.40 m above the middle plane of the LFS,it can achieve a similar deposition depth to the one of its corresponding side.When the pre-cooling effect is taken into account,the deposition depth is predicted to increase only slightly when the pellet is launched from the HFS.The findings of this study will serve as a reference for the update of pellet injection systems for the EAST tokamak.
文摘The micro-ablation processes and morphological evolution of ablative craters on single-crystal magnesium under subpicosecond laser irradiation are investigated using molecular dynamics(MD) simulations and experiments.The simulation results exhibit that the main failure mode of single-crystal Mg film irradiated by a low fluence and long pulse width laser is the ejection of surface atoms,which has laser-induced high stress.However,under high fluence and short pulse width laser irradiation,the main damage mechanism is nucleation fracture caused by stress wave reflection and superposition at the bottom of the film.In addition,Mg[0001] has higher pressure sensitivity and is more prone to ablation than Mg[0001].The evolution equation of crater depth is established using multi-pulse laser ablation simulation and verified by experiments.The results show that,under multiple pulsed laser irradiation,not only does the crater depth increase linearly with the pulse number,but also the quadratic term and constant term of the fitted crater profile curve increase linearly.
基金supported by MEXT Quantum Leap Flagship Program(MEXT Q-LEAP)Grant Number JPMXS0118067246.
文摘GHz burst-mode femtosecond(fs)laser,which emits a series of pulse trains with extremely short intervals of several hundred picoseconds,provides distinct characteristics in materials processing as compared with the conventional irradiation scheme of fs laser(single-pulse mode).In this paper,we take advantage of the moderate pulse interval of 205 ps(4.88 GHz)in the burst pulse for high-quality and high-efficiency micromachining of single crystalline sapphire by laser induced plasma assisted ablation(LIPAA).Specifically,the preceding pulses in the burst generate plasma by ablation of copper placed behind the sapphire substrate,which interacts with the subsequent pulses to induce ablation at the rear surface of sapphire substrates.As a result,not only the ablation quality but also the ablation efficiency and the fabrication resolution are greatly improved compared to the other schemes including single-pulse mode fs laser direct ablation,single-pulse mode fs-LIPAA,and nanosecond-LIPAA.
文摘A controlled model of thermal shield of ablation with trapspiration cooling is develoed. The existence and uniqueness of the classical solution can be obtained by Friedman and Jiang's methods. The positivity of the solution is proved and the conditions for the coolant flux under which the abladtion process will complete in finite time are also determined. Finally, we show the existence of critical coolant flux beyond which the ablation material begin melting.
文摘Background Although elderly patients have been included in published series of catheter ablation for atrial fibrillation （AF）, clinicalbenefit and safety remain still less defined in this population. A retrospective analysis of the results of catheter ablation for AF in a large volumecenter focused on comparison of elderly patients with the rest of the patient cohort was conducted in this study. Methods Consecutive patientswho underwent catheter ablation for AF between January 2001 and December 2016 were analysed. A total population of 3197 patients wasdichotomized by the age of 70 years （394 elderly vs. 2803 younger subjects）. Patients were followed in terms of arrhythmia status and sur-vival for a median period of 18 vs. 21 and 35 vs. 57 months, respectively. Results Elderly patients were more frequently females （49% vs.29%, P 〈 0.0001）, had a history of hypertension （79% vs. 57%, P 〈 0.0001）, diabetes （16% vs. 11%, P 〈 0.01）, stroke （9% vs. 6%, P 〈 0.01）,coronary/peripheral artery disease （14% vs. 8%, P 〈 0.0001）, and CHAzDS2-VASc score （3.1 ± 1.3 vs. 1.5 ± 1.2 s, P 〈 0.0001）. Major com-plications were more frequent in elderly （5.3% vs. 3.2%, P = 0.03）; however, this difference was driven by vascular complications （3.6% vs.1.9%, P = 0.04）. There were comparable rates of cerebrovascular （0.3 vs. 0.3%） or nonvascular complications （1.8 vs. 1.2%）. Good arrhyth-mia control was inferior in elderly patients as compared with the rest of the cohort, both without and with antiarrhythmic drugs： 44.2% vs.58.2% （P 〈 0.0001） and 78.2 vs. 83.2% （P 〈 0.01）, respectively. Poor arrhythmia control was associated with relative risk of all-cause mor-tality of 2.7 （95% CI： 1.1-6.4） in elderly patients and 1.4 （95% CI： 0.9-2.0） in younger subjects. Conclusions Catheter ablation for AF inelderly patients is safe although somewhat less effective. Good arrhythmia control is associated with better survival, especially in elderly patients.
文摘Background Prevalence of atrial fibrillation （AF） increases with age. Radiofrequency catheter ablation （RFCA） is an establishedtreatment option superior to antiarrhythmics （AAs）. In this study, we investigated safety and efficacy of RFCA of AF in octogenarians.Methods From our database, we extracted procedural and follow-up data for patients 〉 80 years with symptomatic AF undergoing RFCAand compared this population to RFCA patients 〈 50 years. All patients underwent pulmonary vein isolation （PVI） supplemented by linearlesions in PVI-nonresponders. Arrhythmia-free survival was assessed using seven day Holter every three months post procedure. All patientscompleted their 12 months follow-up. Results Fifty patients aged ≥80 years （80.5 ± 1.6 years） were compared to 259 patients aged 〈 50years （43.5±5.5 years）. The RFCA complication rate did not vary between groups. No differences in procedural characteristics were seenafter being analyzed by type of AF. Among patients with paroxysmal AF, 71.4% octogenarian vs. 84.7% young patients was free of anyarrhythmia, without AAs, after single procedure. For non-paroxysmal AF, arrhythmia-free survival without AAs, was considerably lower（58.6% octogenarians vs. 81.2% younger patients, P = 0.023）. If AAs were used, arrhythmia-free survival for paroxysmal AF increased to90.5% and 92.1% in octogenarians and younger patients, respectively; and in non-paroxysmal AF it increased to 79.3% vs. 88.4%. ConclusionsRFCA is a safe and effective strategy to achieve normal sinus rhythm in a highly selected group of octogenarians. Paroxysmal AF ablation inoctogenarians has similar clinical effectiveness as that seen in much younger patients. Non-paroxysmal AF ablation has lower, but still rea-sonable clinical effectiveness.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10374116 and 60321003） and the National High Technology Inertial Confinement Fusion Foundation of China.
文摘Compared with direct ablation, confined ablation provides an effective way to obtain a large target momentum and a high coupling coefficient. By using a transparent glass layer to cover the target surface, the coupling coefficient is enhanced by an order of magnitude. With the increase of the gap width between the target surface and the cover layer, the coupling coefficient exponentially decreases. It is found that the coupling coefficient is also related to the thickness of the cover layer.
文摘Backgound Red cell distribution width(RDW) and neutrophil-to-lymphocyte ratio(NLR) are simple hematologic indices that have been used to predict adverse outcomes in different clinical settings. The aim of our study is to determine whether RDW and NLR can predict atrial fibrillation(AF) recurrence in patients undergoing AF ablation. Methods Consecutive patients, without known hematological disorders, who underwent AF catheter ablation between January 2014 and April 2017 were enrolled into this study. Blood samples were taken one day before and five hours after the ablation procedure. Results A total of 346 patients(224 males(65%), mean age: 59 ± 11 years old) were included. After a mean follow up of 26.2 ± 12.1 months, 80(23.1%) patients experienced late AF recurrence(defined as any recurrence after the blanking period of three months), while 97(28%) patients experienced early AF recurrence during the blanking period. Univariate analysis showed that early arrhythmia recurrence, type of AF and NLR after the procedure were significantly associated with late AF recurrence, while early arrhythmia recurrence and NLR remained significant in multivariate analysis. RDW was not associated with late AF recurrence. None of the parameters above predicted early arrhythmia recurrence. Conclusions Simple and inexpensive hematological indices such as NLR should be evaluated for their ability to predict AF recurrence in patients undergoing catheter ablation in larger prospective studies.
基金This work was supported by the national key R&D program for internation-al collaboration under grant No.2018YFE9103900in part by the Nat-ural Science Foundation of China(NSFC)grant No.11972384 and the Guangdong MEPP Fund,grant No.GDOE[2019]A01.
文摘Orientations of laser induced periodic surface structures(LIPSS)are usually considered to be governed by the laser polarization state.In this work,we unveil that fluid dynamics induced by femtosecond(fs)laser ablation in liquid(fs-LAL)can easily break this polarization restriction to produce irregular circular-LIPSS(CLIPPS)and crisscross-LIPSS(CCLIPSS).Fs laser ablation of silicon in water shows formation of diverse LIPSS depending on ablation conditions.At a high power of 700 mW(repetition rate of 100 kHz,pulse duration of 457 fs and wavelength of 1045 nm),single/twin CLIPSS are produced at the bottom of macropores of several microns in diameter due to the formation of strong liquid vortexes and occurrence of the vortex shedding effect.Theoretical simulations validate our speculation about the formation of liquid vortex with an ultrahigh static pressure,which can induce the microstructure trenches and cracks at the sidewalls for fs-LAL of Si and tungsten(W)in water,respectively.At a low power of 50 mW,weak liquid vortexes are produced,which only give birth to curved LIPSS in the valleys of grooves.Consequently,it is deduced that liquid vortex plays a crucial role in the formation of macropores.Mountain-like microstructures induce complex fluid dynamics which can cause the formation of CCLIPSS on them.It is believed that liquid vortexes and fluid dynamics presented in this work open up new possibilities to diversify the morphologies of LIPSS formed by fs-LAL.
文摘Background Atrial fibrillation （AF） catheter ablation has emerged as a promising treatment strategy for AF, but has not been widely adopted in the elderly population. The present study aimed to determine the safety and efficacy of AF catheter ablation in the elderly popula-tion. Methods and Results The study population consisted of 316 patients with paroxysmal AF who underwent left atrial ablation. Ninety-five patients were≥65 years （48 males, mean age 68.9 ± 3.0 years old） and 221 patients were〈65 years old （130 males, mean age 52.5 ± 10.4 years old）. After a mean follow-up period of 34.0 ± 15.1 months, 55 （57.9%） patients in the elderly group were free from ar-rhythmia recurrence compared with 149 （67.4%） patients in the younger group （P=0.169）. Procedural complications were uncommon in both study groups. In logistic regression analysis, left atrial diameter （P=0.003）, hypertension （P=0.001）, dyslipidemia （P=0.039）, and coronary artery disease （P=0.018） were independent predictors of AF recurrence in the elderly population. Conclusions Catheter ablation of AF is safe and effective in older patients. Invasive strategies should be considered as an alternative choice in symptomatic elderly patients with AF.
文摘Background The long-term prognostic influence of left atrial diameter （LAD） remodeling on the status of post-radiofrequency catheter ablation （RI CA） atrial fibrillation （AF） is unclear. This study employed a two-stage model from 3-year echocardiographic data to ascertain whether the two-stage model predicts RFCA outcome more favorably than models using the baseline LAD. Methods Data were retrospectively collected from 263 consecutive patients with drug-refractory AF undergoing RFCA. Regular echocardiographic measurements of LAD were performed at baseline, 1, 3, 6, and 12 months and then every 6 months after RFCA. Sex, age, type of AF, number of RFCA, and AF status were recorded. We obtain the actual （predicted） 3-year LAD using a longitudinal linear mixed model （1st stage）. Logistic regression models based on the baseline LAD （Model 1）, actual （predicted） 3-year LAD （Model 2） （2nd stage）, and observed 3-year LAD （Model 3） were constructed to predict RFCA outcome. The area under the receiver operating characteristic curve （AUC） were used to assess the performance of models. Results The lowess smoothed curve indicated that the LAD declined over the first three months and remained stable up to 36 months after RFCA. The degree of LAD reduction was significantly influenced by the baseline LAD. Non-paroxysmal AF, large LAD and female gender were significant predictors of AF recurrence. Model 2 had the largest AUC among the three models. Conclusions This longitudinal study-based two-stage model outperforms the original logistic model using the baseline LAD. Non-paroxysmal AF, larger LAD and female gender are significant predictors of RFCA failure.
基金the National Key Research and Development Program of China(2017YFC0908803&2018YFC1312501&2016YFC0900901&2016YFC1301002&2020YFC2004803).
文摘Background It is unclear whether catheter ablation(CA)for atrial fibrillation(AF)affects the long-term prognosis in the elderly.This study aims to evaluate the relationship between CA and long-term outcomes in elderly patients with AF.Methods Patients more than 75 years old with non-valvular AF were prospectively enrolled between August 2011 and December 2017 in the Chinese Atrial Fibrillation Registry Study.Participants who underwent CA at baseline were propensity score matched(1:1)with those who did not receive CA.The outcome events included all-cause mortality,cardiovascular mortality,stroke/transient ischemic attack(TIA),and cardiovascular hospitalization.Results Overall,this cohort included 571 ablated patients and 571 non-ablated patients with similar characteristics on 18 dimensions.During a mean follow-up of 39.75±19.98 months(minimum six months),24 patients died in the ablation group,compared with 60 deaths in the non-ablation group[hazard ratio(HR)=0.49,95%confidence interval(CI):0.30-0.79,P=0.0024].Besides,6 ablated and 29 non-ablated subjects died of cardiovascular disease(HR=0.25,95%CI:0.11-0.61,P=0.0022).A total of 27 ablated and 40 non-ablated patients suffered stroke/TIA(HR=0.79,95%CI:0.48-1.28,P=0.3431).In addition,140 ablated and 194 non-ablated participants suffered cardiovascular hospitalization(HR=0.84,95%CI:0.67-1.04,P=0.1084).Subgroup analyses according to gender,type of AF,time since onset of AF,and anticoagulants exposure in initiation did not show significant heterogeneity.Conclusions In elderly patients with AF,CA may be associated with a lower incidence of all-cause and cardiovascular mortality.
文摘High spatial frequency laser induced periodic surface structures(HSFLs)on silicon substrates are often developed on flat surfaces at low fluences near ablation threshold of 0.1 J/cm2,seldom on microstructures or microgrooves at relatively higher fluences above 1 J/cm^2.This work aims to enrich the variety of HSFLs-containing hierarchical microstructures,by femtosecond laser(pulse duration:457 fs,wavelength:1045 nm,and repetition rate:100 kHz)in liquids(water and acetone)at laser fluence of 1.7 J/cm^2.The period of Si-HSFLs in the range of 110–200 nm is independent of the scanning speeds(0.1,0.5,1 and 2 mm/s),line intervals(5,15 and 20μm)of scanning lines and scanning directions(perpendicular or parallel to light polarization direction).It is interestingly found that besides normal HSFLs whose orientations are perpendicular to the direction of light polarization,both clockwise or anticlockwise randomly tilted HSFLs with a maximal deviation angle of 50°as compared to those of normal HSFLSs are found on the microstructures with height gradients.Raman spectra and SEM characterization jointly clarify that surface melting and nanocapillary waves play important roles in the formation of Si-HSFLs.The fact that no HSFLs are produced by laser ablation in air indicates that moderate melting facilitated with ultrafast liquid cooling is beneficial for the formation of HSFLs by LALs.On the basis of our findings and previous reports,a synergistic formation mechanism for HSFLs at high fluence was proposed and discussed,including thermal melting with the concomitance of ultrafast cooling in liquids,transformation of the molten layers into ripples and nanotips by surface plasmon polaritons(SPP)and second-harmonic generation(SHG),and modulation of Si-HSFLs direction by both nanocapillary waves and the localized electric field coming from the excited large Si particles.
文摘Objectives To address whether menopause affects outcome of catheter ablation （CA） for atrial fibrillation （AF） by comparing the safety and long-term outcome of a single-procedure in pre-and post-menopausal women. Methods A total of 743 female patients who underwent a single CA procedure of drug-refractory AF were retrospectively analyzed. The differences in clinical presentation and outcomes of CA for AF between the pre-menopausal women （PreM group, 94 patients, 12.7%） and the post-menopausal women （PostM group, 649 patients, 87.3%） were assessed. Results The patients in the PreM group were younger （P＆lt;0.001） and less likely to have hypertension （P＆lt;0.001） and diabetes （P=0.005） than those in the PostM group. The two groups were similar with regards to the proportion of concomitant mitral valve regurgitation coronary artery disease, left atrium dimensions, and left ventricular ejection fraction. The overall rate of complica-tions related to AF ablation was similar in both groups （P=0.385）. After 43 （16-108） months of follow-up, the success rate of ablation was 54.3%in the PreM group and 54.2%in the PostM group （P=0.842）. The overall freedom from atrial tachyarrhythmia recurrence was simi-lar in both groups. Menopause was not found to be an independent predictive factor of the recurrence of atrial tachyarrhythmia. Conclusions The long-term outcomes of single-procedure CA for AF are similar in pre-and post-menopausal women. Results indicated that CA of AF appears to be as safe and effective in pre-menopausal women as in post-menopausal women.
文摘Backgroud Recent studies have demonstrated that cystatin C is a valuable risk marker for cardiovascular disease morbidity and mortality.Therefore,we hypothesized that the pre-ablation cystatin C level was associated with post-ablation atrial fibrillation(AF)recurrence.Methods 207 patients were enrolled and completed in this prospective observational study.Patients with AF scheduled for receive radiofrequency catheter ablation(RFCA)therapy were screened for the study.Before ablation therapy,electrocardiogram,24 h holter monitor,transesophageal echocardiography,serum cystatin C,high-sensitivity C-reactive protein,creatinine levels,and routine blood examinations were examined.After ablation,patients were followed up every week for the first month,and then at 2,3,6,9,and 12 months.Thereafter,patients came back to out-patient clinic every six months regularly.Electrocardiogram or 24 h holter monitor were repeated if the patient experienced palpitations or every six months.AF recurrence was defined as atrial flbrillation/atrial flutter or atrial tachycardia lasting≥30 seconds within three months after therapy.Results Compared to patients with no AF recurrence,patients with recurrence had longer AF history(P=0.007),more early recurrence(P=0.000),a larger left atrium(P=0.004),and higher pre-ablation cystatin C levels(P=0.000).Multivariate regression analysis revealed that cystatin C and left atria(LA)diameter were risk factors for AF recurrence.After adjusting for LA diameter,the risk of AF recurrence increased 30%with every milligram cystatin C elevation(95%CI:1.117-1.523).Conclusions Pre-ablation cystatin C levels were associated with AF recurrence after RFCA therapy,an optimal cut-off value of 1.190 mg/L(sensitivity=0.576;specificity=0.851).
基金We thank the Deutsche Forschungsgemeinschaft(DFG)for funding within the grants GO 2566/7-1 and GO 2566/8-1.
文摘Understanding shielding cross-effects is a prerequisite for maximal power-specific nanosecond laser ablation in liquids(LAL).However,discrimination between cavitation bubble(CB),nanoparticle(NP),and shielding,e.g.,by the plasma or a transient vapor layer,is challenging.Therefore,CB imaging by shadowgraphy is performed to better understand the plasma and laser beam-NP interaction during LAL.By comparing the fluence-dependent CB volume for ablations performed with 1 ns pulses with reports from the literature,we find larger energy-specific CB volumes for 7 ns-ablation.The increased CB for laser ablation with higher ns pulse durations could be a first explanation of the efficiency decrease reported for these laser systems having higher pulse durations.Consequently,1 ns-LAL shows superior ablation efficiency.Moreover,a CB cascade occurs when the focal plane is shifted into the liquid.This effect is enhanced when NPs are present in the fluid.Even minute amounts of NPs trapped in a stationary layer decrease the laser energy significantly,even under liquid flow.However,this local concentration in the sticking film has so far not been considered.It presents an essential obstacle in high-yield LAL,shielding already the second laser pulse that arrives and presenting a source of satellite bubbles.Hence,measures to lower the NP concentration on the target must be investigated in the future.
文摘Background Atrial fibrillation （AF） is the most frequent arrhythmia, and its prevalence is increasing with aging. We aimed to com-pare the long-term outcome data of patients 〈 65 years vs.≥ 65 years who underwent catheter ablation （CA） for drug-refractory AF. MethodsConsecutive patients with primary pulmonary vein isolation performed between March 2001 and December 2011, and those who completeda five-year of follow-up were divided into two groups： patients aged 〈 65 years into group 1, and patients aged ≥ 65 into group 2. Long-termoutcome data concerning mortality, thromboembolic events （TE） and success rates were compared between these groups. Results A totalnumber of 390 patients were included, group 1 contained 310 patients, and 80 patients in group 2. In group 2, patients had more often impairedrenal function （P 〈 0.001） and thyroid disease （P = 0.047）. A total of fifteen patients died during the 6.63 ± 2.1 years of follow-up, with a sig-nificantly higher incidence in the older group （8/80 vs. 7/310 patients, P = 0.004）. The majority of fatal outcome was due to cancerous dis-eases in both groups. No difference was observed concerning the long-term TE rate （12/310 vs. 4/80 patients, P = 0.75）. Rhythm controlfailed in 25.9% of the patients, with no difference between the groups： 26.4% in group 1 vs. 23.7% in group 2 （P = 0,67）, ConclusionsDespite growing prevalence of AF in aging population, the elderly patients are underrepresented in CA procedures. Similar clinical successand TE complication rate are observed between the age-groups. Our data suggest more liberal criteria might be applied while selecting pa-tients for AF ablation.
文摘The mechanical,thermal and ablation properties of carbon phenolic(C-Ph)composites(Type-I)reinforced with different weight percentages of organo-modified montmorillonite(o-MMT)nanoclay have been studied experimentally.Ball milling was used to disperse different weight(wt)percentages(0,1,2,4,6 wt.%)of nanoclay into phenolic resin.Viscosity changes to resin due to nanoclay was studied.On the other hand,nanoclay added phenolic matrix composites(Type-II)were prepared to study the dispersion of nanoclay in phenolic matrix by small angle X-ray scattering and thermal stability changes to the matrix by thermogravimetric analyser(TGA).This data was used to understand the mechanical,thermal and ablation properties of Type-I composites.Inter laminar shear strength(ILSS),flexural strength and flexural modulus of Type I composites increased by about 29%,12%and 7%respectively at2 wt.%addition of nanoclay beyond which these properties decreased.This was attributed to reduced fiber volume fraction(%Vf)of Type-I composites due to nanoclay addition at such high loadings.Mass ablation rate of Type-I composites was evaluated using oxy acetylene torch test at low heat flux(125 W/cm^(2))and high heat flux levels(500 W/cm^(2)).Mass ablation rates have increased at both flux levels marginally up to 2 wt.%addition of nanoclay beyond which it has increased significantly.This is in contrast to increased thermal stability observed for Type-I and Type-II composites up to 2 wt.%addition of nanoclay.Increased ablation rates due to nanoclay addition was attributed to higher insulation efficiency of nanolcay,which accumulates more heat energy in limited area behind the ablation front and self-propagating ablation mechanisms triggered by thermal decomposition of organic part of nanoclay.
