Epitaxial and large area Sb2Te3 thin films on silicon by MOCVD

Antimony telluride (Sb₂Te₃) thin films were prepared by a room temperature Metal-Organic Chemical Vapor Deposition (MOCVD) process using antimony chloride (SbCl₃) and bis(trimethylsilyl)telluride (Te(SiMe₃)₂) as precursors. Pre-growth and post-growth treatments were found to be pivotal in favoring out-of-plane and in-plane alignment of the crystallites composing the films. A comprehensive suite of characterization techniques were used to evaluate their composition, surface roughness, as well as to assess their morphology, crystallinity, and structural features, revealing that a quick post-growth annealing triggers the formation of epitaxial-quality Sb₂Te₃ films on Si(111).

Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films

The underlying mechanism driving the structural amorphous-to-crystalline transition in Group VI chalcogenides is still a matter of debate even in the simplest GeTe system. We exploit the extreme sensitivity of ⁵⁷Fe emission Mössbauer spectroscopy, following dilute implantation of ⁵⁷Mn (T½ = 1.5 min) at ISOLDE/CERN, to study the electronic charge distribution in the immediate vicinity of the ⁵⁷Fe probe substituting Ge (Fe_Ge), and to interrogate the local environment of Fe_Ge over the amorphous-crystalline phase transition in GeTe thin films. Our results show that the local structure of as-sputtered amorphous GeTe is a combination of tetrahedral and defect-octahedral sites. The main effect of the crystallization is the conversion from tetrahedral to defect-free octahedral sites. We discover that only the tetrahedral fraction in amorphous GeTe participates to the change of the Fe_Ge-Te chemical bonds, with a net electronic charge density transfer of  ~ 1.6 e/a₀ between Fe_Ge and neighboring Te atoms. This charge transfer accounts for a lowering of the covalent character during crystallization. The results are corroborated by theoretical calculations within the framework of density functional theory. The observed atomic-scale chemical-structural changes are directly connected to the macroscopic phase transition and resistivity switch of GeTe thin films.

ANMCO/SIT Consensus Document: telemedicine for cardiovascular emergency networks

Telemedicine has deeply innovated the field of emergency cardiology, particularly the treatment of acute myocardial infarction. The ability to record an ECG in the early prehospital phase, thus avoiding any delay in diagnosing myocardial infarction with direct transfer to the cath-lab for primary angioplasty, has proven to significantly reduce treatment times and mortality. This consensus document aims to analyse the available evidence and organizational models based on a support by telemedicine, focusing on technical requirements, education, and legal aspects.

The future of telemedicine for the management of heart failure patients: a Consensus Document of the Italian Association of Hospital Cardiologists (A.N.M.C.O), the Italian Society of Cardiology (S.I.C.) and the Italian Society for Telemedicine and eHealth (Digital S.I.T.)

Telemedicine applied to heart failure patients is a tool for recording and providing remote transmission, storage and interpretation of cardiovascular parameters and/or useful diagnostic images to allow for intensive home monitoring of patients with advanced heart failure, or during the vulnerable post-acute phase, to improve patient's prognosis and quality of life. Recently, several meta-analyses have shown that telemedicine-supported care pathways are not only effective but also economically advantageous. Benefits seem to be substantial, with a 30-35% reduction in mortality and 15-20% decrease in hospitalizations. Patients implanted with cardiac devices can also benefit from an integrated remote clinical management since all modern devices can transmit technical and diagnostic data. However, telemedicine may provide benefits to heart failure patients only as part of a shared and integrated multi-disciplinary and multi-professional 'chronic care model'. Moreover, the future development of remote telemonitoring programs in Italy will require the primary use of products certified as medical devices, validated organizational solutions as well as legislative and administrative adoption of new care methods and the widespread growth of clinical care competence to remotely manage the complexity of chronicity. Through this consensus document, Italian Cardiology reaffirms its willingness to contribute promoting a new phase of qualitative assessment, standardization of processes and testing of telemedicine-based care models in heart failure. By recognizing the relevance of telemedicine for the care of non-hospitalized patients with heart failure, its strategic importance for the design of innovative models of care, and the many challenges and opportunities it raises, ANMCO and SIC through this document report a consensus on the main directions for its widespread and sustainable clinical implementation.

Charge states and lattice sites of dilute implanted Sn in ZnO

The common charge states of Sn are 2+  and 4+. While charge neutrality considerations favour 2+  to be the natural charge state of Sn in ZnO, there are several reports suggesting the 4+  state instead. In order to investigate the charge states, lattice sites, and the effect of the ion implantation process of dilute Sn atoms in ZnO, we have performed ¹¹⁹Sn emission Mössbauer spectroscopy on ZnO single crystal samples following ion implantation of radioactive ¹¹⁹In (T _½  =  2.4 min) at temperatures between 96 K and 762 K. Complementary perturbed angular correlation measurements on ^111mCd implanted ZnO were also conducted. Our results show that the 2+  state is the natural charge state for Sn in defect free ZnO and that the 4+  charge state is stabilized by acceptor defects created in the implantation process.

[ANMCO/SIC/SIT Consensus document: The future of telemedicine in heart failure]

Telemedicine applied to heart failure patients is a tool for recording, remote transmission, storage and interpretation of cardiocirculatory parameters and/or diagnostic images, useful, as emphasized by the latest guidelines, to allow for intensive home monitoring in patients with advanced heart failure or during the vulnerable post-acute phase to improve the prognosis and quality of life for patients.Recently, several meta-analyses have shown that the patterns of care supported by telemedicine are not only effective, but also economically advantageous. The benefit is unquestionable with a 30-35% reduction in mortality and a 15-20% reduction in hospitalizations. Patients implanted with cardiac devices can also benefit from an integrated remote clinical management as all modern devices can transmit technical and diagnostic data. However, telemedicine can bring benefits to the patient with heart failure only if it is part of a shared and integrated, multidisciplinary and multiprofessional "Chronic Care Model". Moreover, the future development of remote telemonitoring programs in our country goes through the primary use of products certified as medical device, field validation of organizational solutions proposed, a legislative and administrative adaptation to new care methods and the widespread growth of competence in clinical care to remotely manage the complexity of chronicity.With this consensus document the Italian Cardiology reaffirms its willingness to contribute to the government of the tumultuous and fragmented technological development, proposing a new phase of qualitative assessment, standardization of processes and testing the application of telemedicine to heart failure.

[ANMCO/SIT Consensus document: Telemedicine and the emergency/urgency care network]

Telemedicine has deeply innovated the field of emergency cardiology, particularly the treatment of acute myocardial infarction. The ability to record an ECG in the early prehospital phase, thus avoiding any delay in diagnosing myocardial infarction with direct transfer to the cath-lab for primary angioplasty, has proven to significantly reduce treatment times and mortality. This consensus document aims to analyze the available evidence and organizational models based on a support by telemedicine, focusing on technical requirements, education and legal aspects.

Towards a uniform and large-scale deposition of MoS2 nanosheets via sulfurization of ultra-thin Mo-based solid films

Large-scale integration of MoS2 in electronic devices requires the development of reliable and cost-effective deposition processes, leading to uniform MoS2 layers on a wafer scale. Here we report on the detailed study of the heterogeneous vapor-solid reaction between a pre-deposited molybdenum solid film and sulfur vapor, thus resulting in a controlled growth of MoS2 films onto SiO2/Si substrates with a tunable thickness and cm(2)-scale uniformity. Based on Raman spectroscopy and photoluminescence, we show that the degree of crystallinity in the MoS2 layers is dictated by the deposition temperature and thickness. In particular, the MoS2 structural disorder observed at low temperature (<750 °C) and low thickness (two layers) evolves to a more ordered crystalline structure at high temperature (1000 °C) and high thickness (four layers). From an atomic force microscopy investigation prior to and after sulfurization, this parametrical dependence is associated with the inherent granularity of the MoS2 nanosheet that is inherited by the pristine morphology of the pre-deposited Mo film. This work paves the way to a closer control of the synthesis of wafer-scale and atomically thin MoS2, potentially extendable to other transition metal dichalcogenides and hence targeting massive and high-volume production for electronic device manufacturing.

Analysis of the electrical patterns and structural remodeling in atrial fibrillation

Catheter ablation of atrial fibrillation (AF) is a promising therapy, whose success is limited by uncertainty in the knowledge of the mechanisms sustaining the arrhythmia. Many theories based on atrial electrical activation or on atrial structural remodeling have been proposed to target AF mechanisms. We hypothesized two prospective approaches could be linked and both computational analysis of atrial electrical patterns and fibrotic tissue location and extent could give further insights on the role of rotors and spatial relationship between them and atrial fibrosis. This paper presents some preliminary results aimed at the integration of information derived from electrical patterns and structural remodeling in AF patients. Electrical patterns were analyzed by applying the standard procedure based on the Hilbert transform (HT) and with sinusoidal wavelet recomposition (SR). In addition, a new technique based on the detection of maximum negative derivative of the unipolar electrograms and a modified version of signal recomposition (NDSR) was tested.A patient-specific anatomical model was derived by segmenting magnetic resonance angiographic (MRA) data applying an edge based level set approach guided by a phase-based edge detector. A multimodality affine registration was applied to register MRA and delayed-enhanced MR imaging (DE-MRI). Following this registration step, gray intensity levels from DE-MRI were used asa texture of the 3D model to visualize fibrosis location and quantify its extent.In view of a future integration of electrical activation patterns onthe patient-specific anatomical model, detected atrial activation timings (AAT) and derived parameters were validated with manual annotation performed by an expert cardiologist and the atrial model was compared with the anatomical map used to guide the ablation procedure.

Approaches to catheter ablation for persistent atrial fibrillation

BACKGROUND

Catheter ablation is less successful for persistent atrial fibrillation than for paroxysmal atrial fibrillation. Guidelines suggest that adjuvant substrate modification in addition to pulmonary-vein isolation is required in persistent atrial fibrillation.

METHODS

We randomly assigned 589 patients with persistent atrial fibrillation in a 1:4:4 ratio to ablation with pulmonary-vein isolation alone (67 patients), pulmonary-vein isolation plus ablation of electrograms showing complex fractionated activity (263 patients), or pulmonary-vein isolation plus additional linear ablation across the left atrial roof and mitral valve isthmus (259 patients). The duration of follow-up was 18 months. The primary end point was freedom from any documented recurrence of atrial fibrillation lasting longer than 30 seconds after a single ablation procedure.

RESULTS

Procedure time was significantly shorter for pulmonary-vein isolation alone than for the other two procedures (P<0.001). After 18 months, 59% of patients assigned to pulmonary-vein isolation alone were free from recurrent atrial fibrillation, as compared with 49% of patients assigned to pulmonary-vein isolation plus complex electrogram ablation and 46% of patients assigned to pulmonary-vein isolation plus linear ablation (P=0.15). There were also no significant differences among the three groups for the secondary end points, including freedom from atrial fibrillation after two ablation procedures and freedom from any atrial arrhythmia. Complications included tamponade (three patients), stroke or transient ischemic attack (three patients), and atrioesophageal fistula (one patient).

CONCLUSIONS

Among patients with persistent atrial fibrillation, we found no reduction in the rate of recurrent atrial fibrillation when either linear ablation or ablation of complex fractionated electrograms was performed in addition to pulmonary-vein isolation. (Funded by St. Jude Medical; ClinicalTrials.gov number, NCT01203748.).

[Remarks on the guideline recommendations for cardioverter-defibrillator implantation for primary prevention of sudden cardiac Death in patients with severe ventricular dysfunction. Consensus Document of the Italian Association of Hospital Cardiologists (ANMCO)/Italian Society of Cardiology (SIC)/Italian Association of Arrhythmology and Cardiac Pacing (AIAC)]

The indications for implantable cardioverter-defibrillator (ICD) therapy for the prevention of sudden cardiac death in patients with severe left ventricular dysfunction have rapidly expanded over the last 10 years on the basis of the very satisfying results of the numerous randomized clinical trials that have provided the framework for guidelines. However, the analysis of clinical practice in the real world has highlighted some important criticisms in the complex process of selection-management of those patients candidates for ICD therapy: 1) approximately one fourth of all ICD implantations is not justified by clinical evidence, 2) approximately one half of patients with an indication for ICD therapy do not undergo implantation, 3) the benefits from ICD therapy do not apply uniformly to all patients, 4) the relationship between the lifesaving benefit and the potential for harm of ICD therapy is still scarcely known. The main reason for this clinical scenario can be ascribed to the guideline recommendations that are based only on few standard cut-off criteria and therefore too generic and insufficiently detailed. This does not help cardiologists in their decision-making process, and results in fear, uncertainty, and sometimes emotional choices. The aim of this consensus document is to discuss current guideline recommendations and to provide the Italian cardiologists with the most updated information to optimize the selection of patients with severe left ventricular dysfunction who should receive ICD therapy.

Fe charge state adjustment in ZnO upon ion implantation

The influence of the ion implantation process on the charge state of dilute (57)Fe impurities implanted as radioactive (57)Mn in ZnO is investigated by (57)Fe emission Mössbauer spectroscopy. One sample is additionally implanted with stable (23)Na impurities. Both Fe(2+) and Fe(3+) charge states are observed, and the Fe(3+)/Fe(2+) ratio is found to increase with the fluence of both (57)Mn/(57)Fe and (23)Na ions, demonstrating that the build-up of Fe(3+) is not related to the chemical nature of the implanted ions. The results are interpreted in terms of radiation damage induced changes of the Fermi level, and illustrate that the Fe(3+)/Fe(2+) ratio can be adjusted by ion implantation. The spin-lattice relaxation time for Fe(3+) in ZnO is found to be independent of the implantation fluence, and is evidently an intrinsic property of the system.

Incidence and significance of early recurrences associated with different ablation strategies for AF: a STAR-AF substudy

BACKGROUND

Early recurrences of atrial tachyarrhythmias (ERAT) are common after atrial fibrillation (AF) ablation, and predict late recurrences (LR). We sought to determine the impact of different ablation strategies on ERAT and LR.

METHODS AND RESULTS

The STAR-AF trial randomized 100 patients with paroxysmal or persistent AF to ablation of complex fractionated electrograms (CFAE) alone, pulmonary vein isolation (PVI) alone, or combined PVI + CFAE. Patients were followed for 12 months. ERAT was defined as any recurrence of AF, atrial tachycardia, or flutter (AT/AFL) >30 seconds during the first 3 months of follow-up. LR was defined as any recurrence of AF/AT/AFL >30 seconds 3-12 months post. Forty-nine patients experienced ERAT. The index ablation strategy was the only independent predictor of ERAT on multivariate analysis (HR 2.24 PVI vs PVI + CFAE; and HR 2.65 CFAE vs PVI + CFAE). Fifty-two patients experienced LR. The presence of ERAT (HR 3.23), the use of antiarrhythmic drug (AAD) in the first 3 months postablation (HR 2.85), and the index ablation strategy were independently associated with LR (HR 3.42 PVI vs PVI + CFAE; HR 4.72 CFAE vs PVI + CFAE). Thirty-five of 49 (71%) patients with ERAT and 17 (33%) of 51 patients without ERAT had LR (P < 0.0001). Among patients with ERAT, increased left atrium size (HR 1.08), the use of AAD in the first 3 months postablation (HR 2.86) and the index ablation strategy were independently associated with LR (HR 4.77 PVI vs PVI + CFAE; HR 4.45 CFAE vs PVI + CFAE).

CONCLUSION

ERAT is common following AF ablation and is strongly associated with LR. Although CFAE ablation alone results in higher rates of early and LR, the addition of CFAE to PVI results in increased long-term success without an increase in ERAT.

Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial-Part II (STAR AF II): design and rationale

BACKGROUND

The optimal ablation approach for patients with persistent atrial fibrillation (AF) remains unknown. In particular, it is unclear if pulmonary vein (PV) antral isolation (PVI) is sufficient as a lone strategy for persistent AF. Furthermore, if additional substrate ablation is to be added, the ideal approach to substrate ablation is yet to be determined.

OBJECTIVE

The aim of this study is to determine the optimal strategy of catheter ablation of persistent AF by comparing the efficacy of 3 strategies: PVI vs PVI plus complex fractionated electrogram (CFE) ablation (PVI + CFE) vs PVI plus linear ablation (PVI + Lines).

STUDY DESIGN

The STAR AF II study (ClinicalTrials.gov NCT01203748) is a prospective, multicenter, randomized trial with a blinded assessment of outcomes. A total of 549 patients will be randomized in a 1:4:4 fashion to one of the investigation arms: PVI, PVI + CFE, and PVI + Lines, respectively. Patients undergoing a first-time ablation procedure for symptomatic, persistent AF that is refractory to at least 1 antiarrhythmic medication will be included. Persistent AF will be defined as a sustained episode lasting >7 days and <3 years. Patients with a left atrial parasternal size ≥60 mm will be excluded. The primary end point is freedom from documented AF >30 seconds at 18 months after 1 or 2 ablation procedures with or without antiarrhythmic medications.

CONCLUSIONS

The STAR AF II study is a randomized trial designed to evaluate the optimal approach for catheter ablation of persistent AF.