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•Thin films based on LaB6 were produced for novel hybrid thermionic converters.•Deposition assisted by fs laser was used for the first time for films’ fabrication.•A detailed ...physical-chemical study on surface and bulky properties was performed.•Experimental conditions were optimized for enhancing the material’s properties.•Optimal work function and emissivity values were achieved for practical applications.
Lanthanum hexaboride (LaB6)-based thin films were successfully synthesized via femtosecond Pulsed Laser Deposition (fs-PLD) at room temperature and at high growth rate (>110 nm/min) for acting as electron and photon emitters in hybrid thermionic-photovoltaic devices applied in thermal-to-electrical energy conversion. The physical and chemical properties of the films were systematically investigated as a function of the most relevant deposition parameters (laser pulse repetition rate, pressure of the reactor, and deposition time) aimed at optimizing the material’s microstructure and functional optical and electronic properties. Specific growth conditions allowed for the achievement of thin films consisting of nanocrystalline LaB6 (10–20 nm grain-size) with enhanced spectral emissivity and low work function of (2.64 ± 0.03) eV, evaluated by thermionic emission measurements up to 1860 K, where a thermionic current density of 1.78 A cm−2 was measured. The obtained results demonstrate that fs-PLD represents a novel and rapid method for preparing efficient, and low-cost thermal electron emitters for innovative hybrid thermionic conversion devices operating at temperatures close to 2000 K.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Funding Acknowledgements
Type of funding sources: None.
Aim
The aim of this meta-analysis was to systematically investigate the prognostic value of right ventricular (RV) function in ...all-comers patients with significant (at least moderate, ≥ 2+) tricuspid regurgitation (TR).
Background
Chronic significant TR imposes a volume overload to the RV leading to a progressive RV dilatation and dysfunction. A comprehensive assessment of RV function is of paramount importance to guide the therapeutic management of these patients; however, it remains challenging, particularly in presence of altered loading conditions.
Methods
MEDLINE, ISI Web of Science, and SCOPUS databases were searched for studies published up to July 2022. Studies reporting data on at least one echocardiographic RV function parameter and outcome in patients with significant TR were included. This study was designed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) requirements. The primary endpoint was all-cause long-term mortality (more than one year).
Results
Out of 3,152 studies, a total of 10 were included in the analytic synthesis, enrolling 3435 subjects. The median follow-up in our study population was 28 22 – 70 months. All-cause long-term mortality was 40% (95% confidence interval CI: 32–49%, p = 0.028; Figure 1). To explore the potential impact of effect size modifiers on all-cause long-term mortality, we performed a meta-regression analysis of the baseline characteristics of the included studies. At long-term, a significant relation was found between RV fractional area change (RV-FAC), tricuspid annular plane systolic excursion (TAPSE), tricuspid annular tissue doppler imaging systolic velocity (TDI s’) and mortality. In particular, RV-FAC was associated with reduced incidence of all-cause mortality 7 studies enrolling 2,611 subjects, intercept 5.18, slope −0.15, P = 0.007; Figure 2; whereas both TAPSE and TDI s’ were unsatisfactory to predict the outcome in these patients TAPSE 9 studies enrolling 2,891 subjects, intercept 1.73, slope −0.12, P = 0.36; TDI s’ 5 studies enrolling 1429 subjects, intercept −2.06, slope 0.15, P = 0.78. Interestingly, diabetes mellitus (DM) and hyperlipidaemia were associated with an increased risk of mortality DM 9 studies enrolling 3371 subjects, intercept −2.62, slope 0.09, P = 0.004; hyperlipidaemia 6 studies enrolling 2338 subjects, intercept −2.91, slope 0.05, P = 0.01.
Conclusions
Significant TR is associated with increased risk of all-cause. To our knowledge, this is the first study to demonstrate that only RV-FAC, and not conventional echocardiographic indexes of RV longitudinal function, correlates with adverse outcomes in patients with significant TR.
Aims. We perform an extensive characterization of the broadband emission of Mrk 421, as well as its temporal evolution, during the non-flaring (low) state. The high brightness and nearby location (z ...= 0.031) of Mrk 421 make it an excellent laboratory to study blazar emission. The goal is to learn about the physical processes responsible for the typical emission of Mrk 421, which might also be extended to other blazars that are located farther away and hence are more difficult to study. Methods. We performed a 4.5-month multi-instrument campaign on Mrk 421 between January 2009 and June 2009, which included VLBA, F-GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, and Whipple, among other instruments and collaborations. This extensive radio to very-high-energy (VHE; E> 100 GeV) γ-ray dataset provides excellent temporal and energy coverage, which allows detailed studies of the evolution of the broadband spectral energy distribution. Results. Mrk421 was found in its typical (non-flaring) activity state, with a VHE flux of about half that of the Crab Nebula, yet the light curves show significant variability at all wavelengths, the highest variability being in the X-rays. We determined the power spectral densities (PSD) at most wavelengths and found that all PSDs can be described by power-laws without a break, and with indices consistent with pink/red-noise behavior. We observed a harder-when-brighter behavior in the X-ray spectra and measured a positive correlation between VHE and X-ray fluxes with zero time lag. Such characteristics have been reported many times during flaring activity, but here they are reported for the first time in the non-flaring state. We also observed an overall anti-correlation between optical/UV and X-rays extending over the duration of the campaign. Conclusions. The harder-when-brighter behavior in the X-ray spectra and the measured positive X-ray/VHE correlation during the 2009 multi-wavelength campaign suggests that the physical processes dominating the emission during non-flaring states have similarities with those occurring during flaring activity. In particular, this observation supports leptonic scenarios as being responsible for the emission of Mrk 421 during non-flaring activity. Such a temporally extended X-ray/VHE correlation is not driven by any single flaring event, and hence is difficult to explain within the standard hadronic scenarios. The highest variability is observed in the X-ray band, which, within the one-zone synchrotron self-Compton scenario, indicates that the electron energy distribution is most variable at the highest energies.
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FMFMET, NUK, UL, UM, UPUK
Aims. Amongst more than fifty blazars detected in very high energy (VHE, E> 100 GeV) γ rays, only three belong to the subclass of flat spectrum radio quasars (FSRQs). The detection of FSRQs in the ...VHE range is challenging, mainly because of their soft spectra in the GeV-TeV regime. MAGIC observed PKS 1510−089 (z = 0.36) starting 2012 February 3 until April 3 during a high activity state in the high energy (HE, E> 100 MeV) γ-ray band observed by AGILE and Fermi. MAGIC observations result in the detection of a source with significance of 6.0 standard deviations (σ). We study the multi-frequency behaviour of the source at the epoch of MAGIC observation, collecting quasi-simultaneous data at radio and optical (GASP-WEBT and F-Gamma collaborations, REM, Steward, Perkins, Liverpool, OVRO, and VLBA telescopes), X-ray (Swift satellite), and HE γ-ray frequencies. Methods. We study the VHE γ-ray emission, together with the multi-frequency light curves, 43 GHz radio maps, and spectral energy distribution (SED) of the source. The quasi-simultaneous multi-frequency SED from the millimetre radio band to VHE γ rays is modelled with a one-zone inverse Compton model. We study two different origins of the seed photons for the inverse Compton scattering, namely the infrared torus and a slow sheath surrounding the jet around the Very Long Baseline Array (VLBA) core. Results. We find that the VHE γ-ray emission detected from PKS 1510−089 in 2012 February-April agrees with the previous VHE observations of the source from 2009 March-April. We find no statistically significant variability during the MAGIC observations on daily, weekly, or monthly time scales, while the other two known VHE FSRQs (3C 279 and PKS 1222+216) have shown daily scale to sub-hour variability. The γ-ray SED combining AGILE, Fermi and MAGIC data joins smoothly and shows no hint of a break. The multi-frequency light curves suggest a common origin for the millimetre radio and HE γ-ray emission, and the HE γ-ray flaring starts when the new component is ejected from the 43 GHz VLBA core and the studied SED models fit the data well. However, the fast HE γ-ray variability requires that within the modelled large emitting region, more compact regions must exist. We suggest that these observed signatures would be most naturally explained by a turbulent plasma flowing at a relativistic speed down the jet and crossing a standing conical shock.
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Abstract
Background/Introduction
ST-elevation myocardial infarction (STEMI) remains a healthcare burden not only through increased mortality risk, but also development of chronic cardiac pathologies ...like atrial fibrillation (AF). Left atrial (LA) reservoir strain is a known predictor of incident AF in the general population.
Purpose
Our aim was to explore the additional prognostic value of LA reservoir strain measured by transthoracic echocardiography (TTE) in STEMI patients for new-onset atrial fibrillation (NOAF).
Methods
Data were analyzed retrospectively from an ongoing STEMI registry. Patients with previous myocardial infarction, AF, known history of heart failure, severe valvular pathology, suboptimal image quality, AF during TTE or missing follow-up were excluded. TTE was performed within 48 hours of hospitalization. LA reservoir strain was measured in apical 4-chamber view. LA strain <23% was used as cut-off value for impaired LA function as previously established. The endpoint was NOAF. Follow-up was censored at last patient visit or at 5 years.
Results
In total 1238 patients (mean age 60±12 years; 930 (75%) men) were included. After median follow-up of 22 months (IQR 12; 60) 106 (8.6%) patients developed NOAF, most events (71 (67%)) taking place within the first year after STEMI. Mean LA reservoir strain was more impaired in patients who developed NOAF as compared to those who did not (19.3 ± 8.1% versus 24.3 ± 8.8% respectively (p<0.001). Clinical and echocardiographical characteristics are shown in the table. Cumulative event-free survival rates at 1, 3 and 5 years in patients with preserved versus decreased LA strain were 97%, 95% and 93% versus 91%, 89% and 83% respectively (Log-rank X2 = 21.1; p<0.001; Figure). Factors significant on univariable Cox regression analysis (age, presence of chronic obstructive pulmonary disease, troponin levels, left ventricular end-diastolic diameter, interventricular septum diameter, left ventricular global longitudinal strain, LA volume index, LA reservoir strain, E/E’ ratio and right ventricular fractional area change) were included in multivariable model, where LA reservoir strain remained significantly associated with NOAF (HR 0.96 (0.93 – 0.99); p=0.015). Addition of LA strain provided incremental prognostic value over baseline clinical risk factors, traditional TTE parameters and left ventricular global longitudinal strain (X2 84.5 vs 88.8; p=0.013).
Conclusion
LA reservoir strain was associated with new-onset atrial fibrillation in STEMI patients after adjusting for relevant clinical and echocardiographic risk factors.TableFigure
In the MEG II detector, the measurement of the momentum of the charged particle is performed by a high transparency single volume, full stereo cylindrical Drift Chamber (CDCH). It is composed by 9 ...concentric layers, each consisting of 192 drift cells. The single drift cell is approximately squared, with a 20 μm gold plate tungsten sense wire surrounded by 40 μm/50 μm silver plated aluminum field wires in a ratio of 5:1. During the construction of the first CDCH, we observed the breaking of about hundred cathode wires: 97 of these were 40 μm aluminum wires, while 10 were 50 μm wires. Since the number of broken cathodes is less than 1% of the total, one can expect the influence on the track reconstruction efficiency to be not so dramatic. We verified by means of simulations that the loss of one cathode does not change the cell electric field appreciably. Here we present the results of the analysis of the effects of mechanical stress and chemical corrosion observed on these broken wires. Finally, we show the studies carried out on new wires to overcome the weaknesses found and the process that will be used for the construction of the new drift chamber (CDCH2). It will be built with the same modular technique, as for the previous one, the use of the wiring robot will be optimized to improve some weaker step in the procedure, new wires will be adopted with a 25% thicker diameter, which has very little effects on the resolution and efficiency of the detector. Furthermore these wires are made with a manufacturing process different from that used previously.
•Brief description of the MEG CDCH.•Analysis and study of the problems on the wires used in the MEG CDCH.•Analysis and study of the problems on the wires used in the MEG CDCH.•The construction of the new MEG CDCH.•Chemical and SEM analysis of the wires used in the CDCH.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Introduction
Mortality of tricuspid valve (TV) surgery for severe secondary tricuspid regurgitation (TR) remains relatively high. Current guidelines advise surgery in patients with ...symptomatic severe TR as a concomitant procedure to left-sided valve surgery. Right ventricular (RV) dysfunction is an important prognostic marker and may appear late in the natural history of TR. How a staging algorithm of right heart failure (RHF) may impact on TV surgery outcomes has not been evaluated.
Purpose
To evaluate the impact of staging RHF on survival of patients with significant TR undergoing TV surgery.
Methods
Patients diagnosed with significant (moderate and severe) TR who subsequently underwent TV surgery, were staged into 4 groups of progressive disease according to the diagnosis of RV dysfunction and the presence of RHF: stage 1, at risk for RHF; stage 2, RV dysfunction without clinical symptoms of RHF; stage 3, RV dysfunction with symptoms of RHF, and stage 4, RV dysfunction with refractory symptoms of RHF (Figure 1). The study endpoint was all-cause mortality.
Results
A total of 279 patients (mean age 64±12 years, 49% male), were included in the analysis, of which 20 patients (7%) were in stage 1, 14 patients (5%) were in stage 2, 141 patients (51%) were in stage 3 and 104 patients (37%) were in stage 4.
The majority of the patients (266 patients, 95%) underwent TV annuloplasty. Most patients had TV surgery concomitant to left-sided valve surgery or coronary artery bypass grafting (254 patients, 91%). In per-group analysis, patients in stage 4 had significantly larger left ventricular (LV) and RV dimensions, lower LV ejection fraction and more severe diastolic dysfunction than patients in other RHF stages.
During a median follow-up of 65 15 - 106 months after TV surgery, 145 deaths (52%) occurred. The cumulative survival rates were 88%, 77% and 60% at 1 month, 1 year and 5 years, respectively. The Kaplan-Meier curves for overall survival according to RHF stage are shown in Figure 2. Survival rates at 5 years were significantly worse in more advanced stages of RHF: 71% (stage 1 and 2), 66% (stage 3) and 49% (stage 4); log-rank chi-square: 11.302; p=0.004. Right heart failure stage was independently associated with all-cause mortality following adjustment for age, gender, LV ejection fraction, kidney function, TV annulus diameter, concomitant mitral valve surgery and time delay from diagnosis until surgery (p=0.021).
Conclusion
Patients diagnosed with significant TR may benefit from earlier referral for surgical intervention, before presenting with RV dysfunction and before the onset of symptoms of RHF.
Funding Acknowledgement
Type of funding sources: None. Figure 1. Stages of right heart failureFigure 2. Kaplan-Meier curves for overall survival
The ultra-low mass cylindrical drift chamber designed for the MEG II experiment is a challenging apparatus made of 1728 ϕ=20μm gold plated tungsten sense wires, 7680 ϕ=40μm and 2496 ϕ=50μm silver ...plated aluminium field wires. Because of electrostatic stability requirements all the wires have to be stretched at mechanical tensions of ∼25, ∼19 and ∼29g respectively which must be controlled at a level better than 0.5g. This chamber is presently in acquisition, but during its construction ∼100 field wires broke, because of chemical corrosion induced by the atmospheric humidity.
On the basis of the experience gained with this chamber we decided to build a new one, equipped with a different type of wires less sensitive to corrosion. The choice of the new wire required a deep inspection of its characteristics and one of the main tools for doing this is a system for measuring the wire tension by means of the resonant frequency technique, which is described in this paper. The system forces the wires to oscillate by applying a sinusoidal signal at a known frequency, and then measures the variation of the capacitance between a wire and a common ground plane as a function of the external signal frequency. We present the details of the measuring system and the results obtained by scanning the mechanical tensions of two samples of MEG II cylindrical drift chamber wires and discuss the possible improvements of the experimental apparatus and of the measuring technique.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
there is limited evidence regarding the association between right ventricular-to-pulmonary artery (RV-PA) coupling and ...outcomes after transcatheter aortic valve implantation (TAVI). Particularly, the prognostic value of post-TAVI RV-PA coupling has not been investigated so far.
Purpose
We aimed to explore the evolution of RV-PA coupling in patients with severe aortic stenosis (AS) undergoing TAVI and its prognostic impact.
Methods
A total of 900 patients who underwent TAVI in two tertiary centers and with echocardiographic analysis performed within 3 months before and after the procedure were included. RV-PA coupling was measured as the ratio of tricuspid annular plane systolic excursion (TAPSE) to pulmonary artery systolic pressure (PASP). On the basis of current evidence, RV-PA uncoupling was defined by TAPSE/PASP<0.55, whereas a TAPSE//PAS<0.32 identified a severe uncoupling. Primary endpoint was all-cause mortality.
Results
A total of 520 (58%) patients showed RV-PA uncoupling before TAVI, whereas post-TAVI RV-PA uncoupling was observed in 407 (45%) patients. During a median follow-up of 40 months, 250 (28%) deaths occurred. In multivariable Cox regression analyses adjusted for significant clinical, procedural and echocardiographic variables, post-TAVI RV-PA uncoupling was independently associated with an increased risk of mortality (adjusted hazard ratio HR:1.450, 95% Confidence interval CI:1.094–1.921, p = 0.010), while pre-TAVI uncoupling did not. Among patients with post-TAVI RV-PA uncoupling, the presence of severe uncoupling identified a subgroup with the worst survival (adjusted HR: 1.907, 95%CI:1.160–2.815, p = 0.009) (Figure 1). Notably, post-TAVI RV-PA uncoupling provided better risk stratification for all-cause mortality, than its components considered separately (i.e. TAPSE and PASP).
Patients with RV-PA coupling recovery after TAVI (n=173, 33% of patients with pre-TAVI uncoupling) showed similar outcomes as compared to patients with normal coupling. Conversely, the presence of either persistent or new-onset RV-PA uncoupling following TAVI (n=347 and n=67) was associated with an increased risk of death (adjusted HR:1.422, 95%CI:1.025–1.974, p = 0.035 and adjusted HR: 2.247, 95%CI:1.403–3.599, p = 0.001, respectively) (Figure 2).
Conclusions
Post-TAVI RV-PA uncoupling is an independent predictor of long-term mortality, irrespective from coupling before intervention. Assessment of TAPSE/PASP response after TAVI may be helpful to improve patients’ risk stratification.
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