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1.
Nano Lett ; 23(1): 170-176, 2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36562744

RESUMO

Electron doping of graphene has been extensively studied on graphene-supported surfaces, where the metallicity is influenced by the substrate. Herewith we propose potassium adsorption on free-standing nanoporous graphene, thus eluding any effect due to the substrate. We monitor the electron migration in the π* downward-shifted conduction band. In this rigid band shift, we correlate the spectral density of the π* state in the upper Dirac cone with the associated plasmon, blue-shifted with increasing K dose, as deduced by electron energy loss spectroscopy. These results are confirmed by the Dirac plasmon activated by the C 1s emitted electrons, thanks to spatially resolved photoemission. This crosscheck constitutes a reference on the correlation between the electronic π* states in the conduction band and the Dirac plasmon evolution upon in situ electron doping of fully free-standing graphene.

2.
Transplant Proc ; 2022 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-36577636

RESUMO

BACKGROUND: We investigated if the occurrence of preoperative right ventricular dysfunction is capable of influencing heart transplant results in terms of in-hospital mortality, incidence of primary graft dysfunction, and follow-up mortality. METHODS: We retrospectively analyzed 517 patients who underwent heart transplant between January 2000 and December 2020. We defined right ventricular dysfunction (RVD), as central venous pressure (CVP) > 15 mm Hg and CVP/pulmonary capillary wedge pressure ratio > 0.63. We identified 2 subgroups in our population: 33 patients with preoperative RVD and 484 patients without RVD. RESULTS: In-hospital mortality was 7.9%. Severe early graft failure occurred in 6.6% of patients, with 26 patients (5.1%) needing intra-aortic balloon pump and 17 patients (3.3%) needing extracorporeal membrane oxygenation support. Clinical variables that significantly influenced in-hospital mortality were age, peripheral artery disease, and bilirubin > 1.5 mg/dL, while hemodynamic variables influencing in-hospital mortality were CVP (odds ratio [OR], 1.09 [confidence interval {CI}, 1.03-1.15], P = .004], pulmonary artery systolic pressure (OR, 1.02 [CI, 1.00-1.04], P = .05), CVP/pulmonary capillary wedge pressure ratio (OR, 2.78 [CI, 1.14-6.80], P = .025), pulmonary vascular resistance (OR, 1.15 [CI, 1.01-1.32], P = .042), transpulmonary gradient (TPG) (OR, 1.11 [CI, 1.03-1.18], P = .003) , diastolic transpulmonary gradient (OR, 1.10 [CI, 1.02-1.20], P = .015], together with right ventricular dysfunction (OR, 3.56 [CI, 1.44-8.80], P = .011). On the other hand, clinical variables influencing the incidence of early graft failure were body mass index (calculated as weight in kilograms divided by height in meters squared) > 30, peripheral artery disease, bilirubin > 1.5 mg/dL, Model for End-Stage Liver Disease score excluding international normalized ratio before transplant, and preoperative extracorporeal membrane oxygenation support, while hemodynamic variables were pulmonary arterial systolic pressure (OR, 1.03 [CI, 1.00-1.05], P = .016), TPG (OR, 1.08 [1.01-1.17], P = .03), and right ventricular dysfunction (OR, 3.00 [CI, 1.07-8.40] P = .046). On the multivariable analysis, RVD and TPG were independent predictors of in-hospital mortality, while only TPG was a predictor of early graft failure. Follow-up mortality was 38.7% and was influenced by recipient age, recipient body mass index, and preoperative diabetes. Moreover, 1-, 5-, and 10-year survival of patients with preoperative RVD was significantly worse than patients without RVD (log-rank = 0.001). CONCLUSIONS: In our population, RVD influenced both in-hospital and long-term results after heart transplant. For these reasons, it appears crucially important to optimize preoperative right ventricular function to improve these patients' outcomes.

3.
Nanomaterials (Basel) ; 12(15)2022 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-35957041

RESUMO

Atomic deuterium (D) adsorption on free-standing nanoporous graphene obtained by ultra-high vacuum D2 molecular cracking reveals a homogeneous distribution all over the nanoporous graphene sample, as deduced by ultra-high vacuum Raman spectroscopy combined with core-level photoemission spectroscopy. Raman microscopy unveils the presence of bonding distortion, from the signal associated to the planar sp2 configuration of graphene toward the sp3 tetrahedral structure of graphane. The establishment of D-C sp3 hybrid bonds is also clearly determined by high-resolution X-ray photoelectron spectroscopy and spatially correlated to the Auger spectroscopy signal. This work shows that the low-energy molecular cracking of D2 in an ultra-high vacuum is an efficient strategy for obtaining high-quality semiconducting graphane with homogeneous uptake of deuterium atoms, as confirmed by this combined optical and electronic spectro-microscopy study wholly carried out in ultra-high vacuum conditions.

4.
Indian J Thorac Cardiovasc Surg ; 38(Suppl 1): 70-78, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35463719

RESUMO

The treatment of complex aortic arch disease, in chronic or acute setting, has always represented a fascinating challenge for the heart surgeon also because, often, the involvement of the aortic arch is associated with a simultaneous involvement of the ascending aorta and of the proximal portion of the descending thoracic aorta. In recent years, there have been many surgical and/or endovascular techniques and approaches in a single step or multiple steps proposed with the aim of treating and simplifying these complex conditions. The first procedure available for this purpose was the conventional elephant trunk technique, proposed by the German surgeon Hans Borst, back in 1983. In the following years, the technique has undergone modifications, up to what is nowadays considered its most modern evolution, represented by the frozen elephant trunk which allows managing the proximal descending thoracic aorta using the antegrade release of a self-expandable stent graft. In this review article, we try to analyze the advantages and drawbacks of both techniques from clinical and practical points of view.

5.
Ann Cardiothorac Surg ; 11(2): 120-127, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35433353

RESUMO

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare disease with a very complex pathophysiology differing from other causes of pulmonary hypertension (PH). It is an infrequent consequence of acute pulmonary embolism that is frequently misdiagnosed. Pathogenesis has been related to coagulation abnormalities, infection or inflammation, although these disturbances can be absent in many cases. The hallmarks of CTEPH are thrombotic occlusion of pulmonary vessels, variable degree of ventricular dysfunction and secondary microvascular arteriopathy. The definition of CTEPH also includes an increase in mean pulmonary arterial pressure of more than 25 mmHg with a normal pulmonary capillary wedge of less than 15 mmHg. It is classified as World Health Organization group 4 PH, and is the only type that can be surgically cured by pulmonary endarterectomy (PEA). This operation needs to be carried out by a team with strong expertise, from the diagnostic and decisional pathway to the operation itself. However, because the disease has a very heterogeneous phenotype in terms of anatomy, degree of PH and the lack of a standard patient profile, not all cases of CTEPH can be treated by PEA. As a result, PH-directed medical therapy traditionally used for the other types of PH has been proposed and is utilized in CTEPH patients. Since 2015, we have been witnessing the rebirth of balloon pulmonary angioplasty, a technique first performed in 2001 but has since fallen out fashion due to major complications. The refinement of such techniques has allowed its safe utilization as a salvage therapy in inoperable patients. In the present keynote lecture, we will describe these therapeutic approaches and results.

7.
Nano Lett ; 22(7): 2971-2977, 2022 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-35294200

RESUMO

Conversion of free-standing graphene into pure graphane─where each C atom is sp3 bound to a hydrogen atom─has not been achieved so far, in spite of numerous experimental attempts. Here, we obtain an unprecedented level of hydrogenation (≈90% of sp3 bonds) by exposing fully free-standing nanoporous samples─constituted by a single to a few veils of smoothly rippled graphene─to atomic hydrogen in ultrahigh vacuum. Such a controlled hydrogenation of high-quality and high-specific-area samples converts the original conductive graphene into a wide gap semiconductor, with the valence band maximum (VBM) ∼ 3.5 eV below the Fermi level, as monitored by photoemission spectromicroscopy and confirmed by theoretical predictions. In fact, the calculated band structure unequivocally identifies the achievement of a stable, double-sided fully hydrogenated configuration, with gap opening and no trace of π states, in excellent agreement with the experimental results.

8.
Transplant Proc ; 54(3): 774-781, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35279307

RESUMO

BACKGROUND: Currently, guidelines for appropriate donor sizing in recipients mostly focuses on donor-recipient body weight matching. The purpose is to retrospectively determine the impact of predicted heart mass (pHM)-based size matching on heart transplant (HT) outcomes. METHODS: According to our institutional registry, 512 consecutive adult patients underwent HT between January 2000 and August 2020. For each patient, pHM and donor-recipient pHM ratio were calculated. Patients were partitioned into quintiles in terms of pHM ratio: undersizing 2, undersizing 1, reference, oversizing 1, and oversizing 2, with mean pHM donor-recipient ratio of 0.81, 0.96, 1.04, 1.12, and 1.28, respectively. Severe early graft failure and 30-day, 90-day, 1-year, and 10-year mortality were analyzed as outcomes. RESULTS: Recipients of the most oversized group were mostly female (P < .001), had higher preoperative pulmonary vascular resistance (P = .009), had higher rate of mechanical circulatory support (P < .05), and showed a lower United Network for Organ Sharing score (P = .041); the respective donors were younger and more frequently male (P = .001). Ischemic time was similar in all groups (P = .358). Pulmonary vascular resistance (P = .023; odds ratio [OR], 2.38), preoperative mechanical circulatory support (P = .05; OR, 3.06), and United Network for Organ Sharing score (P = .033; OR, 1.76) were identified as risk factors for early mortality. Donor-recipient pHM ratio did not impact early graft failure (P = .871) and early mortality (P = .526). Survival analysis after adjustment for pHM ratio subgroups did not show any difference in outcomes. CONCLUSIONS: A wide range of pHM ratios seems to be safe. A careful allocation of organs, by considering a pHM ratio mismatch, may balance rescue preoperative clinical profiles and preserve HT outcomes.


Assuntos
Transplante de Coração , Transplantes , Adulto , Peso Corporal , Feminino , Sobrevivência de Enxerto , Transplante de Coração/efeitos adversos , Humanos , Masculino , Estudos Retrospectivos , Doadores de Tecidos , Transplantados
9.
J Card Surg ; 37(4): 868-879, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35032070

RESUMO

BACKGROUND: Orthotopic heart transplantation (OHT) remains the gold standard for the treatment of end-stage heart failure. The number of patients who have had at least one prior sternotomy while awaiting transplantation has increased over the years reaching 50% in the last ISHLT registry report. We analysed our institutional transplant activity focusing on prior-sternotomy setting to identify the real burden of this preoperative variable and its potential consequences. METHODS: Between 2000 and 2020, a total of 512 consecutive adult patients underwent OHT. We divided them into two groups according to the previous sternotomy variable: a prior sternotomy group (PS-group, n = 131, 25.6%) and a heart transplant as first sternotomy group (FS-group, n = 381, 74.4%). After propensity score matching, a total of 106 matched-pairs were identified for the final analysis. RESULTS: The overall 30-day mortality was similar in the two groups (7.5% vs. 5.7%, p = .58). The prior sternotomy was not an independent risk factor for 90-day mortality (odds ratio: 0.89, p = .81). In the matched sample, prior cardiac surgery was not predictive for any major postoperative complication: primary graft failure, AKI, bleeding, acute respiratory insufficiency, need for extra-corporeal life support (p > .05). The log-rank test revealed no significant difference between the two groups in the unmatched and matched pools (p = .93 and 0.69 respectively. At univariable analysis prior sternotomy was not associated with an increased risk of posttransplant mortality (hazard ratio: 0.87, p = .599). CONCLUSIONS: Despite it increases surgical complexity, the reoperation alone does not represent a proper risk factor and among different co-variates that may affect post-OHT outcomes.


Assuntos
Transplante de Coração , Esternotomia , Adulto , Aloenxertos , Humanos , Estudos Retrospectivos , Esternotomia/efeitos adversos , Resultado do Tratamento
10.
Ann Thorac Surg ; 113(4): e287-e289, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-34214552

RESUMO

Aberrant right subclavian artery is a relatively rare congenital anomaly of the aortic arch. A 74-year-old woman was referred to our cardiac surgery department for chest pain. Computed tomography angiography scan showed an acute aortic dissection and revealed an aberrant right subclavian artery routed behind the trachea. We performed supracoronary ascending aorta and total arch replacement with the frozen elephant trunk technique. The aberrant right subclavian artery was then anastomosed termino-terminal to one branch of the Thoraflex (Vascutek, Glasgow, Scotland) arch graft. Postoperative computed tomography scan indicated a successful reconstruction of the aortic arch, proving the open stent-grafting technique as a useful and effective approach for aortic disease with aberrant right subclavian artery.


Assuntos
Aneurisma da Aorta Torácica , Implante de Prótese Vascular , Anormalidades Cardiovasculares , Idoso , Aorta Torácica/anormalidades , Aorta Torácica/diagnóstico por imagem , Aorta Torácica/cirurgia , Aneurisma da Aorta Torácica/cirurgia , Implante de Prótese Vascular/métodos , Anormalidades Cardiovasculares/complicações , Anormalidades Cardiovasculares/diagnóstico por imagem , Anormalidades Cardiovasculares/cirurgia , Feminino , Humanos , Artéria Subclávia/anormalidades , Artéria Subclávia/diagnóstico por imagem , Artéria Subclávia/cirurgia
11.
Artif Organs ; 46(5): 813-826, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-34904255

RESUMO

BACKGROUND: We investigated the clinical outcomes after cardiac valvular surgery procedures concomitant (CCPs) with left ventricular assist device (LVAD) implantation compared to propensity score (PS) matched controls using the European Registry for Patients with Mechanical Circulatory Support (EUROMACS) data. METHODS: Between 2006 and 2018, 2760 continuous-flow LVAD patients were identified. Of these, 533 underwent a CCP during the LVAD implant. RESULTS: Cardiopulmonary bypass time (p < 0.001) and time for implant (p < 0.001) were both significantly longer in the LVAD+CCP group. Hospital mortality was comparable between the two groups from the unmatched population (15.7% vs. 14.1%, p = 0.073). Similarly, short-to-mid-term survival was similar in both groups, with 1-year, 3-year, and 5-year survival rates of 67.9%, 48.2%, and 27.7% versus 66.4%, 46.1%, and 26%, respectively (log-rank, p = 0.25). The results were similar in the PS-matched population. Hospital mortality was comparable between the two groups (18.9% vs. 17.4%, p = 0.074). The short-to-mid-term Kaplan-Meier survival analysis was similar for both groups, with 1-year, 3-year, and 5-year survival rates of 63.4%, 49.2%, and 24.7% versus 66.5%, 46%, and 25.1%, respectively (log-rank, p = 0.81). In the unmatched population, LVAD+CCP patients had longer intensive care unit (ICU) stays (p < 0.0001), longer mechanical ventilation time (p = 0.001), a higher rate of temporary right ventricular assist device (RVAD) support (p = 0.033), and a higher rate of renal replacement therapy (n = 35, 6.6% vs. n = 89, 4.0%, p = 0.014). In the PS-matched population, the LVAD+CCP patients had longer ICU stays (p = 0.019) and longer mechanical ventilation time (p = 0.002). CONCLUSIONS: The effect of additive valvular procedures (CCPs) does not seem to affect short-term survival, significantly, based on our registry data analysis. However, the decision to perform CCPs should be balanced with the projected type of surgery and preoperative characteristics. LVAD+CCP patients remain a delicate population and adverse device-related events should be strictly monitored and managed.


Assuntos
Insuficiência Cardíaca , Coração Auxiliar , Insuficiência Cardíaca/epidemiologia , Insuficiência Cardíaca/cirurgia , Coração Auxiliar/efeitos adversos , Humanos , Sistema de Registros , Estudos Retrospectivos , Resultado do Tratamento
12.
J Cardiothorac Vasc Anesth ; 36(5): 1238-1250, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-34785126

RESUMO

In the last 20 years, mechanical circulatory supports (MCS) have overturned completely the outcomes and the clinical recovery of patients with isolated acute left ventricle failure (iALVF). This usually occurs more frequently than right-sided heart failure or biventricular dysfunction, and it mainly is caused by acute myocardial infarction. The primary role of MCS is to restore the tissue metabolism to preserve the vital organs' function but, on the other hand, they also have to relieve the workload stress on the heart. In this way, they allow not only the heart to recover from the acute event, but MCS also can stabilize the patient toward cardiac transplantation. The short-term MCS devices currently used in clinical practice are the intraaortic balloon pump, the Impella (Abiomed, Danvers, MA), and venoarterial extracorporeal membrane oxygenation (VA-ECMO), but the choice of the right and tailored device for each patient, as well as the timing to use it, is actually one of the most debated topics of MCS management.


Assuntos
Oxigenação por Membrana Extracorpórea , Insuficiência Cardíaca , Transplante de Coração , Coração Auxiliar , Oxigenação por Membrana Extracorpórea/efeitos adversos , Insuficiência Cardíaca/etiologia , Insuficiência Cardíaca/cirurgia , Transplante de Coração/efeitos adversos , Coração Auxiliar/efeitos adversos , Humanos , Balão Intra-Aórtico/efeitos adversos , Choque Cardiogênico/etiologia
13.
Medicina (Kaunas) ; 57(10)2021 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-34684127

RESUMO

The frozen elephant trunk technique (FET) requires the use of a pre-assembled hybrid prosthesis consisting of a standard Dacron vascular portion to replace the aortic arch and a stent graft component, which is placed into the proximal descending thoracic aorta (DTA) anterogradely in the proximal descending thoracic aorta. In Europe, two hybrid prostheses are available: the E-evita Open Plus hybrid stent graft system provided by JOTEC (Hechingen, Germany) and the ThoraflexTM Hybrid (Vascutek, Inchinnan Scotland). Recommendations for use are extensive pathologies of the arch in case of acute and chronic aortic dissection, degenerative aneurysm and intramural hematoma. The FET approach allows the replacement of the whole arch in one stage with the option of direct treatment of the proximal descending thoracic aorta based on the stent component, creating a safe landing zone for further endovascular treatment more distally. The remarkable feature of this technique is the possibility to perform more proximally (from zone 3 to zone 0) the distal anastomosis in to the arch. This allows for an easier distal anastomosis, reduced hypothermic circulatory arrest time and decreased risk of paraplegia (<5%). Early results are promising and according to the most recent series the rate of developing post-operative renal insufficiency ranges from 3 to 10%, the risk of stroke from 3% to 8% and mortality from 8-15%. The aim of the article will be to provide some knowledge about the use and application of FET procedures in different aortic situations.


Assuntos
Implante de Prótese Vascular , /cirurgia , Aorta Torácica/cirurgia , Prótese Vascular , Humanos , Stents , Resultado do Tratamento
14.
Materials (Basel) ; 14(19)2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34639887

RESUMO

Heterostructures formed by ultrathin borocarbonitride (BCN) layers grown on TiO2 nanoribbons were investigated as photoanodes for photoelectrochemical water splitting. TiO2 nanoribbons were obtained by thermal oxidation of TiS3 samples. Then, BCN layers were successfully grown by plasma enhanced chemical vapour deposition. The structure and the chemical composition of the starting TiS3, the TiO2 nanoribbons and the TiO2-BCN heterostructures were investigated by Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Diffuse reflectance measurements showed a change in the gap from 0.94 eV (TiS3) to 3.3 eV (TiO2) after the thermal annealing of the starting material. Morphological characterizations, such as scanning electron microscopy and optical microscopy, show that the morphology of the samples was not affected by the change in the structure and composition. The obtained TiO2-BCN heterostructures were measured in a photoelectrochemical cell, showing an enhanced density of current under dark conditions and higher photocurrents when compared with TiO2. Finally, using electrochemical impedance spectroscopy, the flat band potential was determined to be equal in both TiO2 and TiO2-BCN samples, whereas the product of the dielectric constant and the density of donors was higher for TiO2-BCN.

15.
J Card Surg ; 36(10): 3968-3970, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34351022

RESUMO

We report the case of a young woman who underwent cardiac transplantation from systemic lupus erythematosus affected donor and who developed a type A aortic dissection limited only to the graft aortic wall 9 years after.


Assuntos
Transplante de Coração , Lúpus Eritematoso Sistêmico , /diagnóstico por imagem , /cirurgia , Aorta , Feminino , Humanos , Lúpus Eritematoso Sistêmico/complicações
16.
Int J Cardiol ; 335: 26-31, 2021 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-33838151

RESUMO

BACKGROUND: The aims of this study were to analyse the incidence of visceral malperfusion syndrome (MPS) following Frozen Elephant trunk operations in patients affected by chronic aortic dissection and the associated risk factors. METHODS: Between January 2007 and February 2019, 165 patients underwent surgery with FET for chronic aortic dissection. Post-operative computer tomography angiogram parameters (diameters, early post-operative false lumen enhancement and involving of aortic branches by the dissection) were collected and analysed to evaluate their impact on the occurrence of visceral malperfusion. RESULTS: Visceral (renal and mesenteric) MPS (with both clinical and radiological signs of MPS) was detected in 10 cases (6.1%). Post-operative visceral malperfusion was strongly related with in hospital mortality. The involvement of the visceral branches in the dissection was not a risk factor for visceral malperfusion occurrence, while a larger post-operative total aortic diameter at level of the coeliac trunk increased the risk of visceral MPS (OR 1.05; CI 1.002-1.102, p-value = 0.04). Furthermore, visceral MPS was associated to a complete thrombosis of the false lumen at level of the distal descending thoracic aorta. CONCLUSIONS: The development of post-operative MPS in frozen elephant trunk is strongly related to in-hospital mortality. The involvement of aortic branches by the dissection does not represent a real predictive risk factor for MPS, while early larger aortic diameters and false lumen thrombosis represent independent risk factors for MPS and in-hospital mortality.


Assuntos
Aneurisma da Aorta Torácica , Implante de Prótese Vascular , /diagnóstico por imagem , Aorta , Aorta Torácica/cirurgia , Aneurisma da Aorta Torácica/diagnóstico por imagem , Aneurisma da Aorta Torácica/cirurgia , Implante de Prótese Vascular/efeitos adversos , Humanos , Estudos Retrospectivos , Resultado do Tratamento
17.
Cardiovasc Diagn Ther ; 11(1): 277-291, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33708499

RESUMO

Along with the worldwide increase in continuous left ventricular assist device (LVAD) strategy adoption, more and more patients with demanding anatomical and clinical features are currently referred to heart failure (HF) departments for treatment. Thus surgeons have to deal, technically, with re-entry due to previous cardiac surgery procedures, porcelain aorta, peripheral vascular arterial disease, concomitant valvular or septal disease, biventricular failure. New surgical techniques and surgical tools have been developed to offer acceptable postoperative outcomes to all mechanical circulatory support recipients. Several less invasive and/or thoracotomic approaches for surgery combined with various LVAD inflow and outflow graft alternative anastomotic sites for system placement have been reported and described to solve complex clinical scenarios. Surgical techniques have been upgraded with further technical tips to preserve the native anatomy in case of re-entry for heart transplantation, myocardial recovery or device explant. The current continuous-flow miniaturized and intrapericardial devices provide versatility and technical advantages. However, the surgical planning requires a careful multidisciplinary evaluation which must be driven by a dedicated and well-trained Heart Failure team. Biventricular assist device (BVAD) implantation by adoption of the newer radial pumps might be a challenge. However, the results are encouraging thus remaining a valid option. This paper reviews and summarizes LVAD preoperative assessment and current surgical techniques for implantation.

18.
Nanomaterials (Basel) ; 11(1)2021 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-33429994

RESUMO

A suitable way to modify the electronic properties of graphene-while maintaining the exceptional properties associated with its two-dimensional (2D) nature-is its functionalisation. In particular, the incorporation of hydrogen isotopes in graphene is expected to modify its electronic properties leading to an energy gap opening, thereby rendering graphene promising for a widespread of applications. Hence, deuterium (D) adsorption on free-standing graphene was obtained by high-energy electron ionisation of D2 and ion irradiation of a nanoporous graphene (NPG) sample. This method allows one to reach nearly 50 at.% D upload in graphene, higher than that obtained by other deposition methods so far, towards low-defect and free-standing D-graphane. That evidence was deduced by X-ray photoelectron spectroscopy of the C 1s core level, showing clear evidence of the D-C sp3 bond, and Raman spectroscopy, pointing to remarkably clean and low-defect production of graphane. Moreover, ultraviolet photoelectron spectroscopy showed the opening of an energy gap in the valence band. Therefore, high-energy electron ionisation and ion irradiation is an outstanding method for obtaining low defect D-NPG with a high D upload, which is very promising for the fabrication of semiconducting graphane on large scale.

19.
Transplant Proc ; 53(1): 311-317, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32768287

RESUMO

BACKGROUND: The occurrence of early graft failure (EGF) after heart transplantation (Htx) often requires a mechanical circulatory support (MCS) therapy. The aims of our study were to identify risk factors of mechanically supported severe EGF and evaluate their impact on both early and late outcomes. METHODS: Between January 2000 and December 2019, 499 consecutive adult patients underwent Htx at our institution. Severe EGF was defined as the need for extracorporeal life support (ECLS) within 24 hours after surgery. All available recipient and donor variables were retrospectively analyzed. RESULTS: Overall, EGF occurred in 58 (11.6%) patients. Post-Htx peripheral or central ECLS was necessary in 32 (6.4%) cases. Independent predictors of severe EGF were, in the recipient group, preoperative transpulmonary gradient (TPG) >12 mm Hg (odds ratio [OR] 4.1, P = .013), preoperative inotropic score >10 (OR 7.3, P = .0001), and pre-Htx ECLS support (OR 5.2, P = .015), while in the donors, a Eurotransplant donor score ≥17 (OR 8.5, P = .005). The absence of EGF was related with a better survival at 1 year and 5 years (94% and 85%, respectively) compared with EGF requiring ECLS population (36% and 28% at 1 year and 5 years, respectively; P < .001). A five-year conditional survival rate did not differ significantly (85% no EGF vs 83% EGF requiring ECLS). CONCLUSION: Both donor and recipient factors may influence EGF occurrence. Post-Htx ECLS may impact negatively early; however, patients weaned from ECLS eventually benefit from such a rescue treatment with outcomes comparable with Htx patients who did not suffer EGF.


Assuntos
Oxigenação por Membrana Extracorpórea , Transplante de Coração/efeitos adversos , Complicações Pós-Operatórias/terapia , Disfunção Primária do Enxerto/terapia , Adulto , Oxigenação por Membrana Extracorpórea/métodos , Feminino , Transplante de Coração/mortalidade , Humanos , Masculino , Pessoa de Meia-Idade , Razão de Chances , Complicações Pós-Operatórias/epidemiologia , Disfunção Primária do Enxerto/epidemiologia , Estudos Retrospectivos , Fatores de Risco , Taxa de Sobrevida
20.
Nanotechnology ; 32(3): 035707, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33017812

RESUMO

Graphane is formed by bonding hydrogen (and deuterium) atoms to carbon atoms in the graphene mesh, with modification from the pure planar sp2 bonding towards an sp3 configuration. Atomic hydrogen (H) and deuterium (D) bonding with C atoms in fully free-standing nano porous graphene (NPG) is achieved, by exploiting low-energy proton (or deuteron) non-destructive irradiation, with unprecedented minimal introduction of defects, as determined by Raman spectroscopy and by the C 1s core level lineshape analysis. Evidence of the H- (or D-) NPG bond formation is obtained by bringing to light the emergence of a H- (or D-) related sp3-distorted component in the C 1s core level, clear fingerprint of H-C (or D-C) covalent bonding. The H (or D) bonding with the C atoms of free-standing graphene reaches more than 1/4 (or 1/3) at% coverage. This non-destructive H-NPG (or D-NPG) chemisorption is very stable at high temperatures up to about 800 K, as monitored by Raman and x-ray photoelectron spectroscopy, with complete healing and restoring of clean graphene above 920 K. The excellent chemical and temperature stability of H- (and D-) NPG opens the way not only towards the formation of semiconducting graphane on large-scale samples, but also to stable graphene functionalisation enabling futuristic applications in advanced detectors for the ß-spectrum analysis.

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