comparative investigation of mode i and ii fracture toughness of directly cured cfrp and co cured bonded cfrp joints

Abstract Adhesive bonding is the elective joining system between Carbon-Fiber Reinforced Polymer (CFRP) parts because, with respect to fastening, it allows a large connection area, no additional parts (hence weight saving) and no need to drill holes into the composite, that is always detrimental for the strength due to the possibility of developing damage. However, the choice of bonding CFRP should be evaluated as alternative to direct curing in terms of strength and durability, compared to cost and manufacturing time and complexity. In this work, a comparison between directly cured and co-cured, bonded CFRP is done with respect to mode I and mode II fracture toughness, in order to understand whether bonding guarantees the same performance of a co-cured composite part

Etiological diagnosis, prognostic significance and role of electrophysiological study in patients with Brugada ECG and syncope.

BACKGROUND: Syncope is considered a risk factor for life-threatening arrhythmias in Brugada patients. Distinguishing a benign syncope from one due to ventricular arrhythmias is often difficult, unless an ECG is recorded during the episode. Aim of the study was to analyze the characteristics of syncopal episodes in a large population of Brugada patients and evaluate the role of electrophysiological study (EPS) and the prognosis in the different subgroups. METHODS AND RESULTS: One hundred ninety-five Brugada patients with history of syncope were considered. Syncope were classified as neurally mediated (group 1, 61%) or unexplained (group 2, 39%) on the basis of personal and family history, clinical features, triggers, situations, associated signs, concomitant therapy. Most patients underwent EPS; they received ICD or implantable loop-recorder on the basis of the result of investigations and physician's judgment. At 62±45months of mean follow-up, group 1 showed a significantly lower incidence of arrhythmic events (2%) as compared to group 2 (9%, p<0.001). Group 2 patients with positive EPS showed the highest risk of arrhythmic events (27%). No ventricular events occurred in subjects with negative EPS. CONCLUSION: Etiological definition of syncope in Brugada patients is important, as it allows identifying two groups with different outcome. Patients with unexplained syncope and ventricular fibrillation induced at EPS have the highest risk of arrhythmic events. Patients presenting with neurally mediated syncope showed a prognosis similar to that of the asymptomatic and the role of EPS in this group is unproven

Comparison of tensile strength and fracture toughness under mode I and II loading of co-cured and co-bonded CFRP joints

Carbon-Fiber Reinforced Polymer (CFRP) parts are joined mainly using adhesive bonding because, differently from fastening, additional parts (hence weight saving) and through holes (that are always detrimental for the strength due to the possibility of developing damage into the composite) are not necessary. Additionally, it allows for large connection areas, thus distributing stresses better than fastened connections. However, since CFRP can be joined by co-curing, the choice of bonding has to be evaluated as an alternative by a trade-off in terms of strength and durability, compared to cost and manufacturing time and complexity. In this work, a comparison between co-cured and co-bonded CFRP is done with respect to tensile strength and mode I and mode II fracture toughness, in order to understand whether cobonding guarantees the same performance of a co-cured composite par

Spectroscopic analysis of vibronic relaxation pathways in molecular spin qubit [Ho(W5O18)2]9−: sparse spectra are key

Vibrations play a prominent role in magnetic relaxation processes of molecular spin qubits as they couple to spin states, leading to the loss of quantum information. Direct experimental determination of vibronic coupling is crucial to understand and control the spin dynamics of these nano-objects, which represent the limit of miniaturization for quantum devices. Herein, we measure the magneto-infrared properties of the molecular spin qubit system Na9[Ho(W5O18)2]·35H2O. Our results place significant constraints on the pattern of crystal field levels and the vibrational excitations allowing us to unravel vibronic decoherence pathways in this system. We observe field-induced spectral changes near 63 and 370 cm-1 that are modeled in terms of odd-symmetry vibrations mixed with f-manifold crystal field excitations. The overall extent of vibronic coupling in Na9[Ho(W5O18)2]·35H2O is limited by a modest coupling constant (on the order of 0.25) and a transparency window in the phonon density of states that acts to keep the intramolecular vibrations and MJ levels apart. These findings advance the understanding of vibronic coupling in a molecular magnet with atomic clock transitions and suggest strategies for designing molecular spin qubits with improved coherence lifetimes

Telomere Length Variation in Juvenile Acute Myocardial Infarction.

Leukocyte telomere length (LTL) provides a potential marker of biological age, closely related to the endothelial dysfunction and consequently to the atherosclerotic process. To investigate the relationship between the LTL and the risk of premature acute myocardial infarction and to evaluate the predictive value of LTL on the onset of major cardiovascular events, 199 patients from 18 to 48 years old with first diagnosis of acute myocardial infarction were enrolled and were matched with 190 controls for sex and age (± 1 year). Clinical data and coronary artery disease were evaluated at enrollment and at follow up. LTL was measured at enrollment using a quantitative PCR-based method. No significant differences were observed in LTL between cases and controls (p = 0.20) and with the presence of coronary artery disease in patients (p = 0.47). Hypercholesterolemic cases presented LTL significantly longer than cases without hypercholesterolemia (t/s: 0.82 ± 0.16 p = 0.79 and t/s norm: 0.79 ± 0.19 p = 0.01), as confirmed in multivariate regression analysis (p = 0.005, β = 0.09). Furthermore, multivariate regression analysis showed LTL significantly shorter in hypertensive cases than in normotensive cases (p = 0.04, β = -0.07). One hundred seventy-one cases (86%) ended the average follow up of 9 ± 5 years, 92 (54%) presented a major cardiovascular event. At multivariate regression analysis the LTL detected at enrollment did not represent a predictive factor of major cardiovascular events nor it significantly impacted with cumulative events. Based on present cohort of young Italian patients, the LTL did not represent a marker of acute myocardial infarction nor had a predictive role at medium term follow up

Which are the most reliable predictors of recurrence of atrial fibrillation after transcatheter ablation?: a meta-analysis.

Context: Transcatheter ablation of atrial fibrillation (AF) has undergone important development, with acceptable midterm results in terms of the safety and recurrence. A meta-analysis was performed to identify the periprocedural complications, midterm success rates and predictors of recurrence after AF ablation. Methods and results: 4357 patients with paroxysmal AF, 1083 with persistent AF and 1777 with long standing AF were included. The pooled analysis showed that there was an in-hospital complication rate of tamponade requiring drainage of 0.99% (0.44-1.54; CI 99%), stroke with neurological persistent impairment of 0.22% (0.04-0.47; CI 99%), and stroke without of 0.36% (0.03-0.70; CI 99%) After a follow up of 22 (13-28) months and 1.23 (1.19-1.5; CI 99%) procedures per patient, the AF recurrence rate was 31.20% (24.87-34.81; CI 99%). The persistent AF patients exhibited a greater risk of recurrence after the first ablation (OR 1.78 [1.14, 2.77] CI 99%), but a trend towards non significance was present in the patients with more than one procedure (OR 1.69 [0.95, 3.00] CI 99%). The most powerful predictors of an AF ablation failure in the overall population were a recurrence within 30-days (OR 4.30; 2.00-10.80), valvular AF (OR 5.20; 2.22-9.50) and a left atrium diameter of more than 50 mm (OR 5.10 2.00-12.90; all CI 95%). Conclusions: Persistent AF remains burdened from higher recurrence rates, however not so following redo-procedures. Three predictors, valvular AF, a left atrium diameter longer than 50 mm and recurrence within 30 days, could be appraised to drive selection of patients and therapeutic strategy. (C) 2012 Elsevier Ireland Ltd. All rights reserved