Degenerative calcific aortic valve stenosis(AS)is the most common valvular heart disease in elderly.^[1] It is well documented that symptomatic severe AS follows a malignant course leading to cardiogenic shock(CS).
Background In the last years,transcatheter aortic valve implantation(TAVI)indication has expanded to younger and lower risk patients.Consequently,interest in mid and long-term follow up and in the role of life expecta...Background In the last years,transcatheter aortic valve implantation(TAVI)indication has expanded to younger and lower risk patients.Consequently,interest in mid and long-term follow up and in the role of life expectancy,as a key factor for selecting the most tailored treatment,has grown.The aim of this retrospective study is to compare the 4-year survival of patients who underwent aortic valve replacement(AVR)vs.TAVI at our department.Methods From September 2017 to December 2020,673 consecutive patients with severe aortic valve stenosis were enrolled for AVR(n=283)or TAVI(n=390).Inclusion criteria was isolated severe aortic stenosis,while exclusion criteria were redo surgery,valve-in-valve procedure and the need for concomitant surgical procedures.Based on the Lee index,patients were divided into four groups according to their 4-year life expectancy.Four-year survival was assessed and reported using the Kaplan-Meier method.A multivariate regression analysis of risk factors for 4-year mortality was performed.Results Four years survival is always superior in the AVR patients(89.8%vs.75.6%,P<0.001).Surgery is associated with a higher incidence of acute kidney injury(23%vs.5.1%,P<0.001),while TAVI is related to a higher incidence of new onset left bundle branch block(0 vs.23.8%,P<0.001),pace-maker implantation(2.5%vs.11.8%,P=0,02)and mild-to-moderate paravalvular leak(0.3%vs.5.4%,P<0.001).The independent risk factors for 4-years mortality are post-procedural AKI,poor mobility and transcatheter procedure.Conclusion In our analysis,4 years survival is always superior in the AVR patients.Life expectancy is a key factor for selecting the most appropriate approach for each patient.A longer follow up is mandatory before extending TAVI indication to patients with a long-life expectancy.展开更多
The response wavelength of the blocked-impurity-band(BIB)structured infrared detector can reach 200µm,which is the most important very long wavelength infrared astronomical detector.The ion implantation method gr...The response wavelength of the blocked-impurity-band(BIB)structured infrared detector can reach 200µm,which is the most important very long wavelength infrared astronomical detector.The ion implantation method greatly simplifies the fabrication process of the device,but it is easy to cause lattice damage,introduce crystalline defects,and lead to the increase of the dark current of detectors.Herein,the boron-doped germanium ion implantation process was studied,and the involved lattice damage mechanism was discussed.Experimental conditions involved using 80 keV energy for boron ion implantation,with doses ranging from 1×10^(13)cm^(-2)to 3×10^(15)cm^(-2).After implantation,thermal annealing at 450℃was implemented to optimize dopant activation and mitigate the effects of ion implantation.Various sophisticated characterization techniques,including X-ray dif⁃fraction(XRD),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),and secondary ion mass spec⁃trometry(SIMS)were used to clarify lattice damage.At lower doses,no notable structural alterations were ob⁃served.However,as the dosage increased,specific micro distortions became apparent,which could be attributed to point defects and residual strain.The created lattice damage was recovered by thermal treatment,however,an irreversible strain induced by implantation still existed at heavily dosed samples.展开更多
BACKGROUND: This study aims to investigate whether small balloon aortic valvuloplasty(BAV) reduces the need for permanent pacemaker implantation (PPMI) after transcatheter aortic valveimplantation (TAVI).METHODS: This...BACKGROUND: This study aims to investigate whether small balloon aortic valvuloplasty(BAV) reduces the need for permanent pacemaker implantation (PPMI) after transcatheter aortic valveimplantation (TAVI).METHODS: This was a retrospective analysis using data from our local TAVI database. SmallBAV was defined as a small balloon size (=18 mm) pre-dilatation. Normal BAV was defined as aballoon size >18 mm. The primary endpoint was the incidence of new PPMI.RESULTS: Of 99 consecutive TAVI patients, five patients were excluded due to pre-existingpermanent pacemaker. Patients in the small BAV group (n=57) had a signifi cantly lower PPMI ratecompared with the normal BAV group (n=37) (3.5% vs. 18.9%, P=0.026). Moderate or severe aorticvalve regurgitation post-procedure was similar between the small BAV and normal BAV groups (5.3%vs. 8.1%, P=0.480);likewise, the mean aortic gradient post-procedure did not differ significantly(11.5±5.2 mmHg vs. 12.2±7.3 mmHg, 1 mmHg=0.133 kPa, P=0.580) between the groups. Devicesuccess rates were also similar (94.7% vs. 91.8%, P=0.680). In multivariable analysis, small BAV(P=0.027), the ratio of prosthesis diameter to annulus diameter (P=0.048), and mean aortic gradientby echo in the basement (P=0.021) were independent predictors of PPMI.CONCLUSIONS: The small BAV strategy is associated with a low rate of permanentpacemaker implantation after transcatheter self-expanding valve implantation in this single-centerobservational study.展开更多
Background Evaluation of patient outcomes following transcatheter aortic valve implantation （TAVI） has usually been based on survival and clinical improvement. Studies on quality of life are limited, and data from c...Background Evaluation of patient outcomes following transcatheter aortic valve implantation （TAVI） has usually been based on survival and clinical improvement. Studies on quality of life are limited, and data from comprehensive assessments after the procedure are lacking. Methods Sixty patients referred for cardiac rehabilitation after TAVI underwent in-hospital and after-discharge multidimensional assessments to evaluate clinical, functional, and nutritional statuses, degree of autonomy, cognitive impairment, depression and quality of life. Results On admission to rehabilitation, approximately half of the patients had severe functional impairment and dependence for basic activities of daily living. During their hospital stay, one-third of the patients suffered significant clinical complications and two had to be transferred to the implantation center. Despite this, the overall outcome was very good. All of the remaining patients were clinically stable at discharge and functional status, autonomy and quality of life were improved in most. During a mean follow-up of 540 days （range： 192-738 days）, five patients died from noncardiac causes, three were hospitalized for cardiac events, and nine for non cardiac reasons. Functional status and autonomy remained satisfactory in the majority of patients and most continued to live independently. Conclusions Patients referred for rehabilitation after TAVI are often very frail, with a high grade of functional impairment, dependence on others and high risk of clinical complications. During a rehabilitation programme, based on a multidimensional assessment and intervention, most patients showed significant improvement in functional status, quality of life, and autonomy, which remained stable in the majority of subjects during mid-term follow-up.展开更多
Bacillus megaterium BM302 bred by ion-beam implantation produces L-sorbose dehydrogenase accelerative protein （SAP） to accelerate the activity of L-sorbose dehydrogenase （SDH） of Gluconobacter oxydans in the 2-ket...Bacillus megaterium BM302 bred by ion-beam implantation produces L-sorbose dehydrogenase accelerative protein （SAP） to accelerate the activity of L-sorbose dehydrogenase （SDH） of Gluconobacter oxydans in the 2-keto-L-gulonic acid （2KLG） fermentation from L-sorbose by the mixed culture of B. megaterium BM302 and G. oxydans. The SAP purified by three chromatographic steps gave 35-fold purification with a yield of 13% and a specific activity of 5.21 units/mg protein. The molecular weight of the purified SAP was about 58 kDa. The SDH accelerative activity of SAP at pH 7 and 50℃ was the highest. Additionally, it retained 60% activity at a pH range of 6.5 ～ 10 and was stable at 20℃ ～ 60℃. After 0.32-unit SAP was added to the single cultured G. oxydans strains, the SDH activity was apparently accelerated and the 2KLG yield of GO29, GO112, GO and GI13 was enhanced 2.1, 3.3, 3.5 and 2.9 folds respectively over that of the strains without the addition of SAP.展开更多
In order to generate a mutant of Bacillus subtilis with enhanced surface activity through low energy nitrogen ion beam implantation, the effects of energy and dose of ions implanted were studied. The morphological cha...In order to generate a mutant of Bacillus subtilis with enhanced surface activity through low energy nitrogen ion beam implantation, the effects of energy and dose of ions implanted were studied. The morphological changes in the bacteria were observed by scanning electron microscope （SEM）. The optimum condition of ions implantation, 20 keV of energy and 2.6 × 10^15N^＋/cm^2 in dose, was determined. A mutant, B.s-E-8 was obtained, whose surface activity of 50-fold and 100-fold diluted cell-free Landy medium was as 5.6-fold and 17.4-fold as the wild strain. The microbial growth and biosurfactant production of both the mutant and the wild strain were compared. After purified by ultrafiltration and SOURCE 15PHE, the biosurfactant was determined to be a complex of surfactin family through analysis of electrospray ionization mass spectrum （ESI/MS） and there was an interesting finding that after the ion beam implantation the intensities of the components were different from the wild type strain.展开更多
Background Transcatheter aortic valve implantation （TAVI） is a minimally invasive, emerging therapy in surgically high risk, or in- operable patients. Parameters used for risk classification have some deficiencies i...Background Transcatheter aortic valve implantation （TAVI） is a minimally invasive, emerging therapy in surgically high risk, or in- operable patients. Parameters used for risk classification have some deficiencies in the selection of patients. The objective of this study is to evaluate the impact of TAVI on carbohydrate antigen 125 （CA125） and N-terminal pro brain-type natriuretic peptide （NT-proBNP） as biomarkers that have been used frequently in recent years, and also the relationship of these biomarkers to prognosis. Methods ＆ Results Transcatheter aortic valve implantation was practiced on 31 patients in this study. Then, CA125 and NT-proBNP levels studied in patients prior to and after the TAVI were evaluated. The patients were also grouped in accordance with their left ventrieular ejection fraction （LVEF） and CA125 levels （LVEF 〉 40% and 〈 40%; CA125 ≤ 35 U/L and 〉 35 U/L）. The TAVI operation was successfully performed in all patients. There was no in-hospital mortality and substantial improvement in functional capacity was detected at follow ups. In addition, a statistically significant decrease was detected in post-TAVI CA 125 and NT-proBNP levels of all patients （CA 125 83.8 ± 18.1 U/L vs. 64.3 ±14.2 U/L, P = 0.008; NT-proBNP： 4633.6± 627.6 pg/mL vs. 2866.3±536.8 pg/mL, P 〈 0.001）. In groups divided according to the CA125 levels, there was also statistically significant post-TAVI decline in CA125 levels. Within CA125 〉 35 U/L and LVEF 〈 40% groups, the permanent need for a pacemaker was required in one （3.2%） patient and mortality was observed in two （6.4%） patients after TAVI at follow up. Conclusions The results show that TAVI can be performed effectively and reliably in patients with high baseline levels of CA125 and NT-proBNP. These biomarkers are reduced substantially with TAVI, while high biomarker levels are associated with undesired events, and certainly, these biomarkers can be used for risk classifications in patient selection for TAVI.展开更多
As a new mutagenetic method, low-energy ion implantation has been used widely in many research areas in recent years. In order to obtain some industrial strains with high xylanase yield, the wild type strain Aspergill...As a new mutagenetic method, low-energy ion implantation has been used widely in many research areas in recent years. In order to obtain some industrial strains with high xylanase yield, the wild type strain Aspergillus niger A3 was mutated by means of nitrogen ions implantation （10 keV, 2.6× 10^14 ～ 1.56 × 10^15 ions/cm^2） and a mutant N212 was isolated subsequently. However, it was found that the initial screening means of the high-yielding xylanase strains such as transparent halos was unfit for first screening. Compared with that of the wild type strain, xylanase production of the mutant N212 was increased from 320 IU/ml to 610 IU/ml, and the optimum fermentation temperature was increased from 28 ℃ to 30 ℃.展开更多
With ion implantation (N+, energy 10 keV and dosage 1.56×1015 N+cm-2), a high xylanase-producing strain Aspergillus niger N212 was selected. Based on an orthogonal experiment, an optimal fermentation condition wa...With ion implantation (N+, energy 10 keV and dosage 1.56×1015 N+cm-2), a high xylanase-producing strain Aspergillus niger N212 was selected. Based on an orthogonal experiment, an optimal fermentation condition was designed for this high-yield strain. The suitable medium was composed of 8% corncob; 1.0% wheat bran; 0.1%TWEEN20; 0.5% (NH4)2SO4; 0.5%NaNO3; 0.5%FeSO4, 7.5 × 10-4; MnSO4·H2O, 2.5 × 10-4; ZnSO4, 2.0 × 10-4; CoCl2, 3.0 × 10-4. At present, under our experiment condition, xylanase activity of Aspergillus niger N212 reached a level of 600 IU/ml, almost increased by 100% in xylanase production and the time of yielding xylanase was largely reduced to 12 h at 28℃.展开更多
This paper reports that ion implantation to a dose of 1 ×10^17 ions/cm^2 was performed on c-axis-orientated ZnO thin films deposited on （0001） sapphire substrates by the sol-gel technique. After ion implantatio...This paper reports that ion implantation to a dose of 1 ×10^17 ions/cm^2 was performed on c-axis-orientated ZnO thin films deposited on （0001） sapphire substrates by the sol-gel technique. After ion implantation, the as-implanted ZnO films were annealed in argon ambient at different temperatures from 600 - 900 ℃. The effects of ion implantation and post-implantation annealing on the structural and optical properties of the ZnO films were investigated by x-ray diffraction （XRD）, photoluminescence （PL）. It was found that the intensities of （002） peak and near band edge （NBE） exitonic ultraviolet emission increased with increasing annealing temperature from 600- 900 ℃. The defect related deep level emission （DLE） firstly increased with increasing annealing temperature from 600 - 750 ℃, and then decreased quickly with increasing annealing temperature. The recovery of the intensities of NBE and DLE occurs at ～850℃ and ～750℃ respectively. The relative PL intensity ratio of NBE to DLE showed that the quality of ZnO films increased continuously with increasing annealing temperature from 600 - 900 ℃.展开更多
Background In a three-month report from the CGA-TAVI registry, we found the Multidimensional Prognostic Index (MPI) and Short Physical Performance Battery (SPPB) to be of value for predicting short-term outcomes in el...Background In a three-month report from the CGA-TAVI registry, we found the Multidimensional Prognostic Index (MPI) and Short Physical Performance Battery (SPPB) to be of value for predicting short-term outcomes in elderly patients undergoing transcatheter aortic valve implantation (TAVI). In the present analysis, we examined the association of these tools with outcomes up to one year post-TAVI. Methods CGA-TAVI is an international, observational registry of geriatric patients undergoing TAVI. Patients were assessed using the MPI and SPPB. Efficacy of baseline values and any postoperative change for predicting outcome were established using logistic regression. Kaplan- Meier analysis was carried out for each comprehensive geriatric assessment tool, with survival stratified by risk category. Results One year after TAVI, 14.1% of patients deceased, while 17.4% met the combined endpoint of death and/or non-fatal stroke, and 37.7% the combined endpoint of death and/or hospitalisation and/or non-fatal stroke. A high-risk MPI score was associated with an increased risk of all-cause mortality (aOR = 36.13, 95% CI: 2.77–470.78, P = 0.006) and death and/or non-fatal stroke (aOR = 10.10, 95% CI: 1.48–68.75, P = 0.018). No significant associations were found between a high-risk SPPB score and mortality or two main combined endpoints. In contrast to a worsening SPPB, an aggravating MPI score at three months post-TAVI was associated with an increased risk of death and/or non-fatal stoke at one year (aOR = 95.16, 95% CI: 3.41–2657.01). Conclusions The MPI showed value for predicting the likelihood of death and a combination of death and/or non-fatal stroke by one year after TAVI in elderly patients.展开更多
Low-energy ion implantation, as a new technology to produce mutation in plant breeding, has been widely applied in agriculture in China. But so far there is a little understanding of the underlying mechanisms responsi...Low-energy ion implantation, as a new technology to produce mutation in plant breeding, has been widely applied in agriculture in China. But so far there is a little understanding of the underlying mechanisms responsible for its biological effects at the cellular level. Here we report the biological effects of a nitrogen ion beams of 30 keV on the pollen grains of Pinus thunbergii Parl. In general, ion implantation inhibited pollen germination. The dose-response curve presented a particular saddle-like pattern. Ion implantation also changed the dimension of the elongated tubes and significantly induced tip swelling. Confocal microscopy indicated that the pollen tube tips in P. thunbergii contained an enriched network of microtubules. Ion implantation led to the disruption of microtubules especially in swollen tips. Treatment with colchicine demonstrated that tip swelling was caused by the disruption of microtubules in the tip, indicating a unique role for microtubules in maintaining the tip integrality of the pollen tube in conifer. Our results suggest that ion implantation induce the disruption of microtubule organization in pollen and pollen tubes and subsequently cause morphological abnormalities in the pollen tubes. This study may provide a clue for further investigation on the interaction between low-energy ion beams and pollen tube growth.展开更多
The transcatheter aortic valve implantation （TAVI） consist an altemative treatment in patients with severe aortic stenosis. Multimodality imaging using transthoracic echocardiography （TTE） or transesophageal echoc...The transcatheter aortic valve implantation （TAVI） consist an altemative treatment in patients with severe aortic stenosis. Multimodality imaging using transthoracic echocardiography （TTE） or transesophageal echocardiography （TOE） and multislice CT （MSCT） constitute cornerstone techniques for the pre-operative management, peri-procedural guidance, follow up and recognition of possible transcatheter valve related complications. CT angiography is much more accurate regarding the total definition of aortic annulus diameter and circumferential area. Two-dimensional （2D） echocardiography, underestimates the aortic valve annulus diameter compared to 3D imaging techniques （MSCT, MRI and 3D TOE）. Three-dimensional TOE imaging provides measurements of the aortic valve annulus similar to those delivered by MSCT. The pre-procedural MSCT constitutes the gold standard modality minimizing the presence of paravalvular aortic regurgitation, one of the most frequent complications. TOE/TTE and MSCT performance could predict the possibility of pacemaker implantation post-procedural. The presence of a new transient or persisting MR can be assessed well by TOE. Both TTE and TOE, consist initially the basic examination for post TAVI evaluation. In case of transcatheter heart valve failure, the MSCT could be used as additional imaging technique.展开更多
Acute kidney injury following percutaneous coronary intervention （PCI） is associated with a worse outcome. However, the risk factors and outcomes of acute kidney injury （AKI） in patients after intracoronary stent ...Acute kidney injury following percutaneous coronary intervention （PCI） is associated with a worse outcome. However, the risk factors and outcomes of acute kidney injury （AKI） in patients after intracoronary stent implantation are still unknown. A retrospective case control study was done in 325 patients who underwent intracoronary stent implantation from January 2010 to March 2011 at the Drum Tower Hospital of Nanjing University School of Medicine. Those were excluded from the study if they had incomplete clinical data. The patients were divided into a normal group and a AKI group according to the standard of post-operation day 7 to identify AKI. The parameters of the patients included： 1） pre-operative ones： age, gender, hypertension, diabetes mellitus, cerebrovascular disease, left ventricular insufficiency, peripheral angiopathy, creatinine, urea nitrogen, estimated glomerular filtration rate （eGFR）, hyperuricemia, proteinuria, emergency operation, hydration, medications （ACEI/ARBs, statins）; 2） intraoperative ones： dose of contrast media, operative time, hypotension; and 3） postoperative one： hypotension. The parameters were analyzed with univariate analysis and multivariate logistical regression analysis. Of the 325 patients, 51（15.7%） developed AKI. Hospital day and in-hospital mortality were increased significantly in the AKI-group. Univariate analysis showed that age, pre-operative parameters （left ventricular insufficiency, peripheral angiopathy, creatinine, urea nitrogen, estimated glomerular filtration rate, hyperuricemia, proteinuria, hydration）, emergency operation, intraoperative parameters （operative time, hypotension） and postoperative hypotension were significantly different. However, multivariate logistic regression analysis revealed that increased age （OR=0.253, 95%CI=0.088-0.727）, pre-operative proteinuria （OR=5.351, 95%CI=2.128-13.459）, pre-operative left ventricular insufficiency （OR=8.704, 95%CI=3.170-23.898）, eGFR〈60 ml/min/1.73 m2 （OR=6.677, 95%CI=1.167-38.193）, prolonged operative time, intraoperative hypotension （OR=25.245, 95%CI=1.001-1.034） were independent risk factors ofAKl. AKI is a common complication and associated with ominous outcome following intracoronary stent implantation. Increased age, pre-operative proteinuria, pre-operative left ventricular insufficiency, pre-operative low estimated glomerular filtration rate, prolonged operative time, intraoperative hypotension were the significant risk factors ofAKl.展开更多
Background QT dispersion （QTd） is a predictor of ventricular arrhythmia. Ventricular arrhythmia is an important factor influencing morbidity and mortality in patients with aortic stenosis. Surgical aortic valve repl...Background QT dispersion （QTd） is a predictor of ventricular arrhythmia. Ventricular arrhythmia is an important factor influencing morbidity and mortality in patients with aortic stenosis. Surgical aortic valve replacement reduced the QTd in this patients group. However, the effect of transcatheter aortic valve implantation （TAVI） on QTd in patients with aortic stenosis is unknown. The aim of this study was to investigate the effect of TAVI on QTd in patients with aortic stenosis. Methods Patients with severe aortic stenosis, who were not candi-dates for surgical aortic valve replacement due to contraindications or high surgical risk, were included in the study. All patients underwent electrocardiographic and echocardiographic evaluation before, and at the 6th month after TAVI, computed QTd and left ventricular mass index （LVMI）. Results A total 30 patients were admitted to the study （mean age 83.2 ± 1.0 years, female 21 and male 9, mean valve area 0.7 ± 3 mm2）. Edwards SAPIEN heart valves, 23 mm （21 patients） and 26 mm （9 patients）, by the transfemoral approach were used in the TAVI procedures. All TAVI procedures were successful. Both QTd and LVMI at the 6th month after TAVI were significantly reduced com-pared with baseline values of QTd and LVMI before TAVI （73.8 ± 4 ms vs. 68 ± 2 ms, P=0.001 and 198 ± 51 g/m2 vs. 184 ± 40 g/m2, P=0.04, respectively）. There was a significant correlation between QTd and LVMI （r=0.646, P〈0.001）. Conclusions QTd, which malign ventricular arrhythmia marker, and LVMI were significantly reduced after TAVI procedure. TAVI may decrease the possibility of ventricu-lar arrhythmia in patients with aortic stenosis.展开更多
Transcatheter aortic valve implantation （TAV1） represents a real revolution in the field of interventional cardiology for the treatment of elderly or high-risk surgical patients with severe symptomatic aortic valve ...Transcatheter aortic valve implantation （TAV1） represents a real revolution in the field of interventional cardiology for the treatment of elderly or high-risk surgical patients with severe symptomatic aortic valve stenosis. Today, TAVI seems to play a key and a reliable role in the treatment of intermediate and maybe low-risk patients with severe aortic stenosis. TAVI has also evolved from a complex and hazardous procedure into an effective and safe therapy by the development of new generation devices. This article aims to review the background and future of TAVI, elinieal trials and registries with old and new generation TAVI devices and to focus on some open issues related to post-procedural outcomes.展开更多
Background Transcatheter aortic valve implantation （TAVI） has become the standard treatment for patients with severe symptomatic aortic stenosis （AS） considered at very high risk for surgical aortic valve replacem...Background Transcatheter aortic valve implantation （TAVI） has become the standard treatment for patients with severe symptomatic aortic stenosis （AS） considered at very high risk for surgical aortic valve replacement. The purpose of this sub-study was to evaluate long-term （〉 4 years） health-related quality of life （QoL） in octogenarians who underwent TAVI. Methods A single center observational registry in twenty patients who underwent frame analysis assessment ≥ 4 years after TAVI. Health-related QoL was evaluated, using the Short Form-36 （SF-36）, the EuroQoL-5D （EQ-5D） and the visual analogue score （EQ-VAS） questionnaires. Results The mean SF-36 subscale scores at follow-up were physical functioning 40.8 ± 26.3, role physical functioning 67.7 ± 34.9, vitality 54.6 ± 21.6, general health 52.1 ± 20.4, social functioning 63.8 ± 37.7, role emotional functioning 70.2 ± 36.0, mental health 73.2 ± 23.3 and bodily pain 80.9 ± 22.9. The mean EQ-VAS score 〉 4 years after TAVI was 64.7 ± 15.1. With respect to functional class, 80% of the patients were in NYHA class I/II at follow-up compared to 15% prior to TAVI. Conclusions This sub-study reports a significant improvement in functional class （NYHA） in a selected group of very elderly patients 〉 4 years after TAVI. Furthermore, all patients showed a satisfactory QoL despite their age and multiple comorbidities. In addition, our study reveals a lower QoL when compared with the general age matched Dutch population.展开更多
Polytetrafluoroethylene(PTFE)is a low-background polymer that is applied to several applications in rare-event detection and underground low-background experiments.PTFE-based electronic substrates are important for re...Polytetrafluoroethylene(PTFE)is a low-background polymer that is applied to several applications in rare-event detection and underground low-background experiments.PTFE-based electronic substrates are important for reducing the detection limit of high-purity germanium detectors and scintillator calorimeters,which are widely applied in dark matter and 0υββdetection experiments.The traditional adhesive bonding method between PTFE and copper is not conducive to working in liquid nitrogen and extremely low-temperature environments.To avoid adhesive bonding,PTFE must be processed for surface metallization owing to the mismatch between the PTFE and copper conductive layer.Low-background PTFE matrix composites(m-PTFE)were selected to improve the electrical and mechanical properties of PTFE by introducing SiO_(2)/TiO_(2) particles.The microstructures,surface elements,and electrical properties of PTFE and m-PTFE were characterized and analyzed following ion implantation.PTFE and m-PTFE surfaces were found to be broken,degraded,and cross-linked by ion implantation,resulting in C=C conjugated double bonds,increased surface energy,and increased surface roughness.Comparably,the surface roughness,bond strength,and conjugated double bonds of m-PTFE were significantly more intense than those of PTFE.Moreover,the interface bonding theory between PTFE and the metal copper foil was analyzed using the direct metallization principle.Therefore,the peel strength of the optimized electronic substrates was higher than that of the industrial standard at extremely low temperatures,while maintaining excellent electrical properties.展开更多
The monocrystalline LiNbO_(3)(LN)and LiTaO_(3)(LT)plates have been qualified as a kind of material platform for high performance RF filter that is considerable for the 5G communication.LN and LT thin films are usually...The monocrystalline LiNbO_(3)(LN)and LiTaO_(3)(LT)plates have been qualified as a kind of material platform for high performance RF filter that is considerable for the 5G communication.LN and LT thin films are usually transferred on handle wafers by combining ion-slicing and wafer bonding technique to form a piezoelectric on insulator(POI)substrate.The ion implantation is a key process and the implantation-induced strain is essential for the layer transfer.Here,we reported the strain profile of ion implanted rotated Y-cut LN and LT.The ion implantation generates the out-of-plane tensile strain of the sample surface and(006)plane,while both the tensile and compressive strain are observed on the(030)plane.The implanted ions redistributed due to the anisotropy of LN and LT,and induce the main tensile normal to the(006)plane.Meanwhile,the(030)planes are contracted due to the Poisson effect with the interstitial ions disturbing and mainly show a compressive strain profile.展开更多
文摘Degenerative calcific aortic valve stenosis(AS)is the most common valvular heart disease in elderly.^[1] It is well documented that symptomatic severe AS follows a malignant course leading to cardiogenic shock(CS).
文摘Background In the last years,transcatheter aortic valve implantation(TAVI)indication has expanded to younger and lower risk patients.Consequently,interest in mid and long-term follow up and in the role of life expectancy,as a key factor for selecting the most tailored treatment,has grown.The aim of this retrospective study is to compare the 4-year survival of patients who underwent aortic valve replacement(AVR)vs.TAVI at our department.Methods From September 2017 to December 2020,673 consecutive patients with severe aortic valve stenosis were enrolled for AVR(n=283)or TAVI(n=390).Inclusion criteria was isolated severe aortic stenosis,while exclusion criteria were redo surgery,valve-in-valve procedure and the need for concomitant surgical procedures.Based on the Lee index,patients were divided into four groups according to their 4-year life expectancy.Four-year survival was assessed and reported using the Kaplan-Meier method.A multivariate regression analysis of risk factors for 4-year mortality was performed.Results Four years survival is always superior in the AVR patients(89.8%vs.75.6%,P<0.001).Surgery is associated with a higher incidence of acute kidney injury(23%vs.5.1%,P<0.001),while TAVI is related to a higher incidence of new onset left bundle branch block(0 vs.23.8%,P<0.001),pace-maker implantation(2.5%vs.11.8%,P=0,02)and mild-to-moderate paravalvular leak(0.3%vs.5.4%,P<0.001).The independent risk factors for 4-years mortality are post-procedural AKI,poor mobility and transcatheter procedure.Conclusion In our analysis,4 years survival is always superior in the AVR patients.Life expectancy is a key factor for selecting the most appropriate approach for each patient.A longer follow up is mandatory before extending TAVI indication to patients with a long-life expectancy.
基金Supported by National Key R&D Program of China(2023YFA1608701)National Natural Science Foundation of China(62274168,11933006,U2141240)Hangzhou Leading Innovation and Entrepreneurship Team(TD2020002)。
文摘The response wavelength of the blocked-impurity-band(BIB)structured infrared detector can reach 200µm,which is the most important very long wavelength infrared astronomical detector.The ion implantation method greatly simplifies the fabrication process of the device,but it is easy to cause lattice damage,introduce crystalline defects,and lead to the increase of the dark current of detectors.Herein,the boron-doped germanium ion implantation process was studied,and the involved lattice damage mechanism was discussed.Experimental conditions involved using 80 keV energy for boron ion implantation,with doses ranging from 1×10^(13)cm^(-2)to 3×10^(15)cm^(-2).After implantation,thermal annealing at 450℃was implemented to optimize dopant activation and mitigate the effects of ion implantation.Various sophisticated characterization techniques,including X-ray dif⁃fraction(XRD),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),and secondary ion mass spec⁃trometry(SIMS)were used to clarify lattice damage.At lower doses,no notable structural alterations were ob⁃served.However,as the dosage increased,specific micro distortions became apparent,which could be attributed to point defects and residual strain.The created lattice damage was recovered by thermal treatment,however,an irreversible strain induced by implantation still existed at heavily dosed samples.
基金supported by National Key R & D Plan(2017YFC1104202).
文摘BACKGROUND: This study aims to investigate whether small balloon aortic valvuloplasty(BAV) reduces the need for permanent pacemaker implantation (PPMI) after transcatheter aortic valveimplantation (TAVI).METHODS: This was a retrospective analysis using data from our local TAVI database. SmallBAV was defined as a small balloon size (=18 mm) pre-dilatation. Normal BAV was defined as aballoon size >18 mm. The primary endpoint was the incidence of new PPMI.RESULTS: Of 99 consecutive TAVI patients, five patients were excluded due to pre-existingpermanent pacemaker. Patients in the small BAV group (n=57) had a signifi cantly lower PPMI ratecompared with the normal BAV group (n=37) (3.5% vs. 18.9%, P=0.026). Moderate or severe aorticvalve regurgitation post-procedure was similar between the small BAV and normal BAV groups (5.3%vs. 8.1%, P=0.480);likewise, the mean aortic gradient post-procedure did not differ significantly(11.5±5.2 mmHg vs. 12.2±7.3 mmHg, 1 mmHg=0.133 kPa, P=0.580) between the groups. Devicesuccess rates were also similar (94.7% vs. 91.8%, P=0.680). In multivariable analysis, small BAV(P=0.027), the ratio of prosthesis diameter to annulus diameter (P=0.048), and mean aortic gradientby echo in the basement (P=0.021) were independent predictors of PPMI.CONCLUSIONS: The small BAV strategy is associated with a low rate of permanentpacemaker implantation after transcatheter self-expanding valve implantation in this single-centerobservational study.
文摘Background Evaluation of patient outcomes following transcatheter aortic valve implantation （TAVI） has usually been based on survival and clinical improvement. Studies on quality of life are limited, and data from comprehensive assessments after the procedure are lacking. Methods Sixty patients referred for cardiac rehabilitation after TAVI underwent in-hospital and after-discharge multidimensional assessments to evaluate clinical, functional, and nutritional statuses, degree of autonomy, cognitive impairment, depression and quality of life. Results On admission to rehabilitation, approximately half of the patients had severe functional impairment and dependence for basic activities of daily living. During their hospital stay, one-third of the patients suffered significant clinical complications and two had to be transferred to the implantation center. Despite this, the overall outcome was very good. All of the remaining patients were clinically stable at discharge and functional status, autonomy and quality of life were improved in most. During a mean follow-up of 540 days （range： 192-738 days）, five patients died from noncardiac causes, three were hospitalized for cardiac events, and nine for non cardiac reasons. Functional status and autonomy remained satisfactory in the majority of patients and most continued to live independently. Conclusions Patients referred for rehabilitation after TAVI are often very frail, with a high grade of functional impairment, dependence on others and high risk of clinical complications. During a rehabilitation programme, based on a multidimensional assessment and intervention, most patients showed significant improvement in functional status, quality of life, and autonomy, which remained stable in the majority of subjects during mid-term follow-up.
基金the General Program of National Science Foundation of China(No.10375066)
文摘Bacillus megaterium BM302 bred by ion-beam implantation produces L-sorbose dehydrogenase accelerative protein （SAP） to accelerate the activity of L-sorbose dehydrogenase （SDH） of Gluconobacter oxydans in the 2-keto-L-gulonic acid （2KLG） fermentation from L-sorbose by the mixed culture of B. megaterium BM302 and G. oxydans. The SAP purified by three chromatographic steps gave 35-fold purification with a yield of 13% and a specific activity of 5.21 units/mg protein. The molecular weight of the purified SAP was about 58 kDa. The SDH accelerative activity of SAP at pH 7 and 50℃ was the highest. Additionally, it retained 60% activity at a pH range of 6.5 ～ 10 and was stable at 20℃ ～ 60℃. After 0.32-unit SAP was added to the single cultured G. oxydans strains, the SDH activity was apparently accelerated and the 2KLG yield of GO29, GO112, GO and GI13 was enhanced 2.1, 3.3, 3.5 and 2.9 folds respectively over that of the strains without the addition of SAP.
基金supported by the Knowledge Innovation Project of the Chinese Academy of Sciences (No.KSCX2-SW-324)
文摘In order to generate a mutant of Bacillus subtilis with enhanced surface activity through low energy nitrogen ion beam implantation, the effects of energy and dose of ions implanted were studied. The morphological changes in the bacteria were observed by scanning electron microscope （SEM）. The optimum condition of ions implantation, 20 keV of energy and 2.6 × 10^15N^＋/cm^2 in dose, was determined. A mutant, B.s-E-8 was obtained, whose surface activity of 50-fold and 100-fold diluted cell-free Landy medium was as 5.6-fold and 17.4-fold as the wild strain. The microbial growth and biosurfactant production of both the mutant and the wild strain were compared. After purified by ultrafiltration and SOURCE 15PHE, the biosurfactant was determined to be a complex of surfactin family through analysis of electrospray ionization mass spectrum （ESI/MS） and there was an interesting finding that after the ion beam implantation the intensities of the components were different from the wild type strain.
文摘Background Transcatheter aortic valve implantation （TAVI） is a minimally invasive, emerging therapy in surgically high risk, or in- operable patients. Parameters used for risk classification have some deficiencies in the selection of patients. The objective of this study is to evaluate the impact of TAVI on carbohydrate antigen 125 （CA125） and N-terminal pro brain-type natriuretic peptide （NT-proBNP） as biomarkers that have been used frequently in recent years, and also the relationship of these biomarkers to prognosis. Methods ＆ Results Transcatheter aortic valve implantation was practiced on 31 patients in this study. Then, CA125 and NT-proBNP levels studied in patients prior to and after the TAVI were evaluated. The patients were also grouped in accordance with their left ventrieular ejection fraction （LVEF） and CA125 levels （LVEF 〉 40% and 〈 40%; CA125 ≤ 35 U/L and 〉 35 U/L）. The TAVI operation was successfully performed in all patients. There was no in-hospital mortality and substantial improvement in functional capacity was detected at follow ups. In addition, a statistically significant decrease was detected in post-TAVI CA 125 and NT-proBNP levels of all patients （CA 125 83.8 ± 18.1 U/L vs. 64.3 ±14.2 U/L, P = 0.008; NT-proBNP： 4633.6± 627.6 pg/mL vs. 2866.3±536.8 pg/mL, P 〈 0.001）. In groups divided according to the CA125 levels, there was also statistically significant post-TAVI decline in CA125 levels. Within CA125 〉 35 U/L and LVEF 〈 40% groups, the permanent need for a pacemaker was required in one （3.2%） patient and mortality was observed in two （6.4%） patients after TAVI at follow up. Conclusions The results show that TAVI can be performed effectively and reliably in patients with high baseline levels of CA125 and NT-proBNP. These biomarkers are reduced substantially with TAVI, while high biomarker levels are associated with undesired events, and certainly, these biomarkers can be used for risk classifications in patient selection for TAVI.
基金the National Key Technologies R & D Program of China during the 10th Five-Year Plan(No.2001BA302B)
文摘As a new mutagenetic method, low-energy ion implantation has been used widely in many research areas in recent years. In order to obtain some industrial strains with high xylanase yield, the wild type strain Aspergillus niger A3 was mutated by means of nitrogen ions implantation （10 keV, 2.6× 10^14 ～ 1.56 × 10^15 ions/cm^2） and a mutant N212 was isolated subsequently. However, it was found that the initial screening means of the high-yielding xylanase strains such as transparent halos was unfit for first screening. Compared with that of the wild type strain, xylanase production of the mutant N212 was increased from 320 IU/ml to 610 IU/ml, and the optimum fermentation temperature was increased from 28 ℃ to 30 ℃.
文摘With ion implantation (N+, energy 10 keV and dosage 1.56×1015 N+cm-2), a high xylanase-producing strain Aspergillus niger N212 was selected. Based on an orthogonal experiment, an optimal fermentation condition was designed for this high-yield strain. The suitable medium was composed of 8% corncob; 1.0% wheat bran; 0.1%TWEEN20; 0.5% (NH4)2SO4; 0.5%NaNO3; 0.5%FeSO4, 7.5 × 10-4; MnSO4·H2O, 2.5 × 10-4; ZnSO4, 2.0 × 10-4; CoCl2, 3.0 × 10-4. At present, under our experiment condition, xylanase activity of Aspergillus niger N212 reached a level of 600 IU/ml, almost increased by 100% in xylanase production and the time of yielding xylanase was largely reduced to 12 h at 28℃.
文摘This paper reports that ion implantation to a dose of 1 ×10^17 ions/cm^2 was performed on c-axis-orientated ZnO thin films deposited on （0001） sapphire substrates by the sol-gel technique. After ion implantation, the as-implanted ZnO films were annealed in argon ambient at different temperatures from 600 - 900 ℃. The effects of ion implantation and post-implantation annealing on the structural and optical properties of the ZnO films were investigated by x-ray diffraction （XRD）, photoluminescence （PL）. It was found that the intensities of （002） peak and near band edge （NBE） exitonic ultraviolet emission increased with increasing annealing temperature from 600- 900 ℃. The defect related deep level emission （DLE） firstly increased with increasing annealing temperature from 600 - 750 ℃, and then decreased quickly with increasing annealing temperature. The recovery of the intensities of NBE and DLE occurs at ～850℃ and ～750℃ respectively. The relative PL intensity ratio of NBE to DLE showed that the quality of ZnO films increased continuously with increasing annealing temperature from 600 - 900 ℃.
基金provided by Edwards Lifesciences (Nyon, Switzerland) to the Sponsor IPPMed (Cloppenburg, Germany)funding from Edwards Lifesciences as did Andrea Ungar
文摘Background In a three-month report from the CGA-TAVI registry, we found the Multidimensional Prognostic Index (MPI) and Short Physical Performance Battery (SPPB) to be of value for predicting short-term outcomes in elderly patients undergoing transcatheter aortic valve implantation (TAVI). In the present analysis, we examined the association of these tools with outcomes up to one year post-TAVI. Methods CGA-TAVI is an international, observational registry of geriatric patients undergoing TAVI. Patients were assessed using the MPI and SPPB. Efficacy of baseline values and any postoperative change for predicting outcome were established using logistic regression. Kaplan- Meier analysis was carried out for each comprehensive geriatric assessment tool, with survival stratified by risk category. Results One year after TAVI, 14.1% of patients deceased, while 17.4% met the combined endpoint of death and/or non-fatal stroke, and 37.7% the combined endpoint of death and/or hospitalisation and/or non-fatal stroke. A high-risk MPI score was associated with an increased risk of all-cause mortality (aOR = 36.13, 95% CI: 2.77–470.78, P = 0.006) and death and/or non-fatal stroke (aOR = 10.10, 95% CI: 1.48–68.75, P = 0.018). No significant associations were found between a high-risk SPPB score and mortality or two main combined endpoints. In contrast to a worsening SPPB, an aggravating MPI score at three months post-TAVI was associated with an increased risk of death and/or non-fatal stoke at one year (aOR = 95.16, 95% CI: 3.41–2657.01). Conclusions The MPI showed value for predicting the likelihood of death and a combination of death and/or non-fatal stroke by one year after TAVI in elderly patients.
基金supported by National Key Project of China (No. 2001BA302B)
文摘Low-energy ion implantation, as a new technology to produce mutation in plant breeding, has been widely applied in agriculture in China. But so far there is a little understanding of the underlying mechanisms responsible for its biological effects at the cellular level. Here we report the biological effects of a nitrogen ion beams of 30 keV on the pollen grains of Pinus thunbergii Parl. In general, ion implantation inhibited pollen germination. The dose-response curve presented a particular saddle-like pattern. Ion implantation also changed the dimension of the elongated tubes and significantly induced tip swelling. Confocal microscopy indicated that the pollen tube tips in P. thunbergii contained an enriched network of microtubules. Ion implantation led to the disruption of microtubules especially in swollen tips. Treatment with colchicine demonstrated that tip swelling was caused by the disruption of microtubules in the tip, indicating a unique role for microtubules in maintaining the tip integrality of the pollen tube in conifer. Our results suggest that ion implantation induce the disruption of microtubule organization in pollen and pollen tubes and subsequently cause morphological abnormalities in the pollen tubes. This study may provide a clue for further investigation on the interaction between low-energy ion beams and pollen tube growth.
文摘The transcatheter aortic valve implantation （TAVI） consist an altemative treatment in patients with severe aortic stenosis. Multimodality imaging using transthoracic echocardiography （TTE） or transesophageal echocardiography （TOE） and multislice CT （MSCT） constitute cornerstone techniques for the pre-operative management, peri-procedural guidance, follow up and recognition of possible transcatheter valve related complications. CT angiography is much more accurate regarding the total definition of aortic annulus diameter and circumferential area. Two-dimensional （2D） echocardiography, underestimates the aortic valve annulus diameter compared to 3D imaging techniques （MSCT, MRI and 3D TOE）. Three-dimensional TOE imaging provides measurements of the aortic valve annulus similar to those delivered by MSCT. The pre-procedural MSCT constitutes the gold standard modality minimizing the presence of paravalvular aortic regurgitation, one of the most frequent complications. TOE/TTE and MSCT performance could predict the possibility of pacemaker implantation post-procedural. The presence of a new transient or persisting MR can be assessed well by TOE. Both TTE and TOE, consist initially the basic examination for post TAVI evaluation. In case of transcatheter heart valve failure, the MSCT could be used as additional imaging technique.
文摘Acute kidney injury following percutaneous coronary intervention （PCI） is associated with a worse outcome. However, the risk factors and outcomes of acute kidney injury （AKI） in patients after intracoronary stent implantation are still unknown. A retrospective case control study was done in 325 patients who underwent intracoronary stent implantation from January 2010 to March 2011 at the Drum Tower Hospital of Nanjing University School of Medicine. Those were excluded from the study if they had incomplete clinical data. The patients were divided into a normal group and a AKI group according to the standard of post-operation day 7 to identify AKI. The parameters of the patients included： 1） pre-operative ones： age, gender, hypertension, diabetes mellitus, cerebrovascular disease, left ventricular insufficiency, peripheral angiopathy, creatinine, urea nitrogen, estimated glomerular filtration rate （eGFR）, hyperuricemia, proteinuria, emergency operation, hydration, medications （ACEI/ARBs, statins）; 2） intraoperative ones： dose of contrast media, operative time, hypotension; and 3） postoperative one： hypotension. The parameters were analyzed with univariate analysis and multivariate logistical regression analysis. Of the 325 patients, 51（15.7%） developed AKI. Hospital day and in-hospital mortality were increased significantly in the AKI-group. Univariate analysis showed that age, pre-operative parameters （left ventricular insufficiency, peripheral angiopathy, creatinine, urea nitrogen, estimated glomerular filtration rate, hyperuricemia, proteinuria, hydration）, emergency operation, intraoperative parameters （operative time, hypotension） and postoperative hypotension were significantly different. However, multivariate logistic regression analysis revealed that increased age （OR=0.253, 95%CI=0.088-0.727）, pre-operative proteinuria （OR=5.351, 95%CI=2.128-13.459）, pre-operative left ventricular insufficiency （OR=8.704, 95%CI=3.170-23.898）, eGFR〈60 ml/min/1.73 m2 （OR=6.677, 95%CI=1.167-38.193）, prolonged operative time, intraoperative hypotension （OR=25.245, 95%CI=1.001-1.034） were independent risk factors ofAKl. AKI is a common complication and associated with ominous outcome following intracoronary stent implantation. Increased age, pre-operative proteinuria, pre-operative left ventricular insufficiency, pre-operative low estimated glomerular filtration rate, prolonged operative time, intraoperative hypotension were the significant risk factors ofAKl.
文摘Background QT dispersion （QTd） is a predictor of ventricular arrhythmia. Ventricular arrhythmia is an important factor influencing morbidity and mortality in patients with aortic stenosis. Surgical aortic valve replacement reduced the QTd in this patients group. However, the effect of transcatheter aortic valve implantation （TAVI） on QTd in patients with aortic stenosis is unknown. The aim of this study was to investigate the effect of TAVI on QTd in patients with aortic stenosis. Methods Patients with severe aortic stenosis, who were not candi-dates for surgical aortic valve replacement due to contraindications or high surgical risk, were included in the study. All patients underwent electrocardiographic and echocardiographic evaluation before, and at the 6th month after TAVI, computed QTd and left ventricular mass index （LVMI）. Results A total 30 patients were admitted to the study （mean age 83.2 ± 1.0 years, female 21 and male 9, mean valve area 0.7 ± 3 mm2）. Edwards SAPIEN heart valves, 23 mm （21 patients） and 26 mm （9 patients）, by the transfemoral approach were used in the TAVI procedures. All TAVI procedures were successful. Both QTd and LVMI at the 6th month after TAVI were significantly reduced com-pared with baseline values of QTd and LVMI before TAVI （73.8 ± 4 ms vs. 68 ± 2 ms, P=0.001 and 198 ± 51 g/m2 vs. 184 ± 40 g/m2, P=0.04, respectively）. There was a significant correlation between QTd and LVMI （r=0.646, P〈0.001）. Conclusions QTd, which malign ventricular arrhythmia marker, and LVMI were significantly reduced after TAVI procedure. TAVI may decrease the possibility of ventricu-lar arrhythmia in patients with aortic stenosis.
文摘Transcatheter aortic valve implantation （TAV1） represents a real revolution in the field of interventional cardiology for the treatment of elderly or high-risk surgical patients with severe symptomatic aortic valve stenosis. Today, TAVI seems to play a key and a reliable role in the treatment of intermediate and maybe low-risk patients with severe aortic stenosis. TAVI has also evolved from a complex and hazardous procedure into an effective and safe therapy by the development of new generation devices. This article aims to review the background and future of TAVI, elinieal trials and registries with old and new generation TAVI devices and to focus on some open issues related to post-procedural outcomes.
文摘Background Transcatheter aortic valve implantation （TAVI） has become the standard treatment for patients with severe symptomatic aortic stenosis （AS） considered at very high risk for surgical aortic valve replacement. The purpose of this sub-study was to evaluate long-term （〉 4 years） health-related quality of life （QoL） in octogenarians who underwent TAVI. Methods A single center observational registry in twenty patients who underwent frame analysis assessment ≥ 4 years after TAVI. Health-related QoL was evaluated, using the Short Form-36 （SF-36）, the EuroQoL-5D （EQ-5D） and the visual analogue score （EQ-VAS） questionnaires. Results The mean SF-36 subscale scores at follow-up were physical functioning 40.8 ± 26.3, role physical functioning 67.7 ± 34.9, vitality 54.6 ± 21.6, general health 52.1 ± 20.4, social functioning 63.8 ± 37.7, role emotional functioning 70.2 ± 36.0, mental health 73.2 ± 23.3 and bodily pain 80.9 ± 22.9. The mean EQ-VAS score 〉 4 years after TAVI was 64.7 ± 15.1. With respect to functional class, 80% of the patients were in NYHA class I/II at follow-up compared to 15% prior to TAVI. Conclusions This sub-study reports a significant improvement in functional class （NYHA） in a selected group of very elderly patients 〉 4 years after TAVI. Furthermore, all patients showed a satisfactory QoL despite their age and multiple comorbidities. In addition, our study reveals a lower QoL when compared with the general age matched Dutch population.
基金supported by the National Natural Science Foundation of China(Nos.12141502 and 12005017).
文摘Polytetrafluoroethylene(PTFE)is a low-background polymer that is applied to several applications in rare-event detection and underground low-background experiments.PTFE-based electronic substrates are important for reducing the detection limit of high-purity germanium detectors and scintillator calorimeters,which are widely applied in dark matter and 0υββdetection experiments.The traditional adhesive bonding method between PTFE and copper is not conducive to working in liquid nitrogen and extremely low-temperature environments.To avoid adhesive bonding,PTFE must be processed for surface metallization owing to the mismatch between the PTFE and copper conductive layer.Low-background PTFE matrix composites(m-PTFE)were selected to improve the electrical and mechanical properties of PTFE by introducing SiO_(2)/TiO_(2) particles.The microstructures,surface elements,and electrical properties of PTFE and m-PTFE were characterized and analyzed following ion implantation.PTFE and m-PTFE surfaces were found to be broken,degraded,and cross-linked by ion implantation,resulting in C=C conjugated double bonds,increased surface energy,and increased surface roughness.Comparably,the surface roughness,bond strength,and conjugated double bonds of m-PTFE were significantly more intense than those of PTFE.Moreover,the interface bonding theory between PTFE and the metal copper foil was analyzed using the direct metallization principle.Therefore,the peel strength of the optimized electronic substrates was higher than that of the industrial standard at extremely low temperatures,while maintaining excellent electrical properties.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFB1803902)the National Natural Science Foundation of China(Grant Nos.11905282,61874128,61851406,11705262,and 6187407)+4 种基金the Frontier Science Key Program of CAS(Grant Nos.QYZDY-SSWJSC032 and ZDBS-LY-JSC009)Chinese-Austrian Cooperative Research and Development Project(Grant No.GJHZ201950)the Program of Shanghai Academic Research Leader(Grant No.19XD1404600)K.C.Wong Education Foundation(Grant No.GJTD-2019-11),Shanghai Sailing Program(Grant Nos.19YF1456200 and 19YF1456400)Shanghai Science and Technology Innovation Action Plan Program(Grant No.19XD1404600)。
文摘The monocrystalline LiNbO_(3)(LN)and LiTaO_(3)(LT)plates have been qualified as a kind of material platform for high performance RF filter that is considerable for the 5G communication.LN and LT thin films are usually transferred on handle wafers by combining ion-slicing and wafer bonding technique to form a piezoelectric on insulator(POI)substrate.The ion implantation is a key process and the implantation-induced strain is essential for the layer transfer.Here,we reported the strain profile of ion implanted rotated Y-cut LN and LT.The ion implantation generates the out-of-plane tensile strain of the sample surface and(006)plane,while both the tensile and compressive strain are observed on the(030)plane.The implanted ions redistributed due to the anisotropy of LN and LT,and induce the main tensile normal to the(006)plane.Meanwhile,the(030)planes are contracted due to the Poisson effect with the interstitial ions disturbing and mainly show a compressive strain profile.
