Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
2.
Anal Bioanal Chem ; 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-36447098

RESUMO

Gold films coated with a graphene sheet are being widely used as sensors for the detection of label-free binding interactions using surface plasmon resonance (SPR). During the preparation of such sensors, it is often essential to subject the sensor chips to a high-temperature treatment in order to ensure a clean graphene surface. However, sensor chips used currently, which often use chromium as an adhesion promoter, cannot be subjected to temperatures above 250 °C, because under such conditions, chromium is found to reorganize and diffuse to the surface, where it is easily oxidized, impairing the quality of SPR spectra. Here we present an optimized preparation strategy involving a three-cycle tempering coupled with chromium (oxide) etching, which allows the graphene-coated SPR chips to be annealed up to 500 °C with little deterioration of the surface morphology. In addition, the treatment delivers a surface that shows a clear enhancement in spectral response together with a good refractive index sensitivity. We demonstrate the applicability of our sensors by studying the kinetics of avidin-biotin binding at different pH repeatedly on the same chip. The possibility to anneal can be exploited to recover the original surface after sensing trials, which allowed us to reuse the sensor for at least six cycles of biomolecule adsorption.

3.
ACS Nano ; 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-36449748

RESUMO

Clean oxide surfaces are generally hydrophilic. Water molecules anchor at undercoordinated surface metal atoms that act as Lewis acid sites, and they are stabilized by H bonds to undercoordinated surface oxygens. The large unit cell of In2O3(111) provides surface atoms in various configurations, which leads to chemical heterogeneity and a local deviation from this general rule. Experiments (TPD, XPS, nc-AFM) agree quantitatively with DFT calculations and show a series of distinct phases. The first three water molecules dissociate at one specific area of the unit cell and desorb above room temperature. The next three adsorb as molecules in the adjacent region. Three more water molecules rearrange this structure and an additional nine pile up above the OH groups. Despite offering undercoordinated In and O sites, the rest of the unit cell is unfavorable for adsorption and remains water-free. The first water layer thus shows ordering into nanoscopic 3D water clusters separated by hydrophobic pockets.

4.
Chemphyschem ; 21(16): 1788-1796, 2020 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-32639106

RESUMO

Difficulties associated with the integration of liquids into a UHV environment make surface-science style studies of mineral dissolution particularly challenging. Recently, we developed a novel experimental setup for the UHV-compatible dosing of ultrapure liquid water and studied its interaction with TiO2 and Fe3 O4 surfaces. Herein, we describe a simple approach to vary the pH through the partial pressure of CO2 ( p C O 2 ) in the surrounding vacuum chamber and use this to study how these surfaces react to an acidic solution. The TiO2 (110) surface is unaffected by the acidic solution, except for a small amount of carbonaceous contamination. The Fe3 O4 (001)-( 2 × 2 )R45° surface begins to dissolve at a pH 4.0-3.9 ( p C O 2 =0.8-1 bar) and, although it is significantly roughened, the atomic-scale structure of the Fe3 O4 (001) surface layer remains visible in scanning tunneling microscopy (STM) images. X-ray photoelectron spectroscopy (XPS) reveals that the surface is chemically reduced and contains a significant accumulation of bicarbonate (HCO3 - ) species. These observations are consistent with Fe(II) being extracted by bicarbonate ions, leading to dissolved iron bicarbonate complexes (Fe(HCO3 )2 ), which precipitate onto the surface when the water evaporates.

5.
Can J Cardiol ; 36(7): 1152-1155, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32447060

RESUMO

The diffusion of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) forced the Italian population to restrictive measures that modified patients' responses to non-SARS-CoV-2 medical conditions. We evaluated all patients with acute coronary syndromes admitted in 3 high-volume hospitals during the first month of SARS-CoV-2 Italian-outbreak and compared them with patients with ACS admitted during the same period 1 year before. Hospitalization for ACS decreased from 162 patients in 2019 to 84 patients in 2020. In 2020, both door-to-balloon and symptoms-to-percutaneous coronary intervention were longer, and admission levels of high-sensitive cardiac troponin I were higher. They had a lower discharged residual left-ventricular function and an increased predicted late cardiovascular mortality based on their Global Registry of Acute Coronary Events (GRACE) scores.


Assuntos
Síndrome Coronariana Aguda/terapia , Infecções por Coronavirus/epidemiologia , Pandemias/estatística & dados numéricos , Intervenção Coronária Percutânea/estatística & dados numéricos , Pneumonia Viral/epidemiologia , Sistema de Registros , Tempo para o Tratamento/estatística & dados numéricos , Síndrome Coronariana Aguda/diagnóstico , Síndrome Coronariana Aguda/mortalidade , Adulto , Idoso , COVID-19 , Estudos de Coortes , Surtos de Doenças/estatística & dados numéricos , Feminino , Mortalidade Hospitalar/tendências , Hospitalização/estatística & dados numéricos , Hospitais com Alto Volume de Atendimentos , Humanos , Itália/epidemiologia , Masculino , Pessoa de Meia-Idade , Intervenção Coronária Percutânea/métodos , Estudos Retrospectivos , Medição de Risco , Estatísticas não Paramétricas , Taxa de Sobrevida , Resultado do Tratamento
6.
J Chem Phys ; 151(15): 154702, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31640372

RESUMO

Atomic-scale investigations of metal oxide surfaces exposed to aqueous environments are vital to understand degradation phenomena (e.g., dissolution and corrosion) as well as the performance of these materials in applications. Here, we utilize a new experimental setup for the ultrahigh vacuum-compatible dosing of liquids to explore the stability of the Fe3O4(001)-(√2 × âˆš2)R45° surface following exposure to liquid and ambient pressure water. X-ray photoelectron spectroscopy and low-energy electron diffraction data show that extensive hydroxylation causes the surface to revert to a bulklike (1 × 1) termination. However, scanning tunneling microscopy (STM) images reveal a more complex situation, with the slow growth of an oxyhydroxide phase, which ultimately saturates at approximately 40% coverage. We conclude that the new material contains OH groups from dissociated water coordinated to Fe cations extracted from subsurface layers and that the surface passivates once the surface oxygen lattice is saturated with H because no further dissociation can take place. The resemblance of the STM images to those acquired in previous electrochemical STM studies leads us to believe that a similar structure exists at the solid-electrolyte interface during immersion at pH 7.

7.
J Phys Chem Lett ; 10(10): 2487-2492, 2019 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-31039610

RESUMO

The interaction of water with the most prominent surfaces of Fe3O4, (001) and (111), is directly compared using a combination of temperature-programmed desorption, temperature-programmed low energy electron diffraction (TP LEED), and scanning probe microscopies. Adsorption on the (√2 × âˆš2)R45°-reconstructed surface of Fe3O4(001) is strongly influenced by the surface reconstruction, which remains intact at all coverages. Close to the completion of the first monolayer, however, the ad-layer adopts a longer-range (2 × 2) superstructure. This finding is discussed in the context of a similar (2 × 2) superstructure recently observed on the (111) facet, which exists over a significantly larger range of temperatures and coverages. In both cases, the long-range order is evidence that water-water interactions exert a significant influence on the structure already prior to the nucleation of the second layer. We conclude that the stability differences stem from the smaller unit cell on the (111) surface, and the ability of water to more easily form stable hexagonal ice-like structures on the hexagonal substrate.

8.
Phys Chem Chem Phys ; 20(23): 15764-15774, 2018 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-29868669

RESUMO

We monitored adsorption of water on a well-defined Fe3O4(111) film surface at different temperatures as a function of coverage using infrared reflection-absorption spectroscopy, temperature programmed desorption, and single crystal adsorption calorimetry. Additionally, density functional theory was employed using a Fe3O4(111)-(2 × 2) slab model to generate 15 energy minimum structures for various coverages. Corresponding vibrational properties of the adsorbed water species were also computed. The results show that water molecules readily dissociate on regular surface Fetet1-O ion pairs to form "monomers", i.e., terminal Fe-OH and surface OH groups. Further water molecules adsorb on the hydroxyl covered surface non-dissociatively and form "dimers" and larger oligomers, which ultimately assemble into an ordered (2 × 2) hydrogen-bonded network structure with increasing coverage prior to the formation of a solid water film.

9.
Angew Chem Int Ed Engl ; 57(5): 1409-1413, 2018 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-29205761

RESUMO

The initial stages of water adsorption on magnetite Fe3 O4 (111) surface and the atomic structure of the water/oxide interface remain controversial. Herein, we provide experimental results obtained by infrared reflection-absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD), corroborated by density functional theory (DFT) calculations showing that water readily dissociates on Fetet sites to form two hydroxo species. These act as an anchor for water molecules to form a dimer complex which self-assembles into an ordered (2×2) structure. Water ad-layer ordering is rationalized in terms of a cooperative effect induced by a hydrogen-bonding network.

10.
Phys Chem Chem Phys ; 18(20): 13960-73, 2016 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-27149902

RESUMO

Atomistic-level understanding of the interaction of α,ß-unsaturated aldehydes and their derivatives with late transition metals is of fundamental importance for the rational design of new catalytic materials with the desired selectivity towards C[double bond, length as m-dash]C vs. C[double bond, length as m-dash]O bond partial hydrogenation. In this study, we investigate the interaction of acrolein, and its partial hydrogenation products propanal and allyl alcohol, with Pd(111) as a prototypical system. A combination of infrared reflection-absorption spectroscopy (IRAS) and temperature programmed desorption (TPD) experiments was applied under well-defined ultrahigh vacuum (UHV) conditions to obtain detailed information on the adsorption geometries of acrolein, propanal, and allyl alcohol as a function of coverage. We compare the IR spectra obtained for multilayer coverages, reflecting the molecular structure of unperturbed molecules, with the spectra acquired for sub-monolayer coverages, at which the chemical bonds of the molecules are strongly distorted. Coverage-dependent IR spectra of acrolein on Pd(111) point to the strong changes in the adsorption geometry with increasing acrolein coverage. Acrolein adsorbs with the C[double bond, length as m-dash]C and C[double bond, length as m-dash]O bonds lying parallel to the surface in the low coverage regime and changes its geometry to a more upright orientation with increasing coverage. TPD studies indicate decomposition of the species adsorbed in the sub-monolayer regime upon heating. Similar strong coverage dependence of the IR spectra were found for propanal and allyl alcohol. For all investigated molecules a detailed assignment of vibrational bands is reported.

11.
Angew Chem Int Ed Engl ; 54(47): 13942-6, 2015 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-26457889

RESUMO

We present a mechanistic study on the interaction of water with a well-defined model Fe3O4(111) surface that was investigated by a combination of direct calorimetric measurements of adsorption energies, infrared vibrational spectroscopy, and calculations bases on density functional theory (DFT). We show that the adsorption energy of water (101 kJ mol(-1)) is considerably higher than all previously reported values obtained by indirect desorption-based methods. By employing (18)O-labeled water molecules and an Fe3 O4 substrate, we proved that the generally accepted simple model of water dissociation to form two individual OH groups per water molecule is not correct. DFT calculations suggest formation of a dimer, which consists of one water molecule dissociated into two OH groups and another non-dissociated water molecule creating a thermodynamically very stable dimer-like complex.

12.
J Colloid Interface Sci ; 437: 270-276, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25441360

RESUMO

Understanding the factors that governs spontaneous molecular transfer from solution to solid surface is fundamental to control noncovalent surface functionalization strategies, both in term of robustness and reproducibility. The comprehension of the nature of interaction involved in the mechanism of spontaneous adsorption will allow for a fine modulation of the deposition process. Herein, we provide experimental evidences to demonstrate that poly-lysine secondary structure represents a crucial factor profoundly influencing the outcome of its spontaneous deposition on quartz surfaces. In particular, random coil to α-helix transition is required to drive an effective transfer of the poly-l-lysine at the liquid-solid interface. ß-sheet deposition requires longer times to be accomplished, while random-coil deposition is highly unfavored. Accordingly, polylysine deposition on quartz and silicon is effective when α-helix is formed in solution (pH>10). This surface noncovalent functionalization represents a simple strategy to fabricate hybrid organic-inorganic or biocompatible materials. In fact, the proposed methodology is proven robust and repeatable and compatible for combination with solution or vapor phases (i.e. MOCVD) nanomaterial deposition approaches.


Assuntos
Polilisina/química , Dicroísmo Circular , Microscopia Eletrônica de Varredura , Estrutura Secundária de Proteína , Espectrofotometria Ultravioleta , Propriedades de Superfície
13.
Artigo em Inglês | MEDLINE | ID: mdl-25544117

RESUMO

Since the first human catheterization performed by Forssman in 1929 angioplasty equipment and medical therapies have undergone considerable evolution and technical improvement allowing interventionalists to perform more complex procedures and solving most of the percutaneous limitations. While percutaneous coronary intervention (PCI) has dramatically changed the outcome in the Acute Coronary Syndrome (ACS) setting, its role in the treatment of chronic stable angina is still debated. Stable coronary artery disease (SCAD) is a major public health issue and its prevalence is still increasing in the industrialized world. The correct treatment sees a multi-strategy approach aimed to a relief of symptoms, prevention of future cardiac events and survival improvement. In so forth, treatment strategies include optimal medical therapy (OMT) alone or combined with percutaneous or surgical coronary revascularization. Despite this, angina remains poorly controlled in the vast majority of CAD patients. Traditional agents such Beta-blockers or Calcium channel blockers or short and long acting nitrates have been used as first-line anti-anginal therapy for several years. Nowadays newer and more effective drugs usually used on top of older medical treatment have become available.


Assuntos
Angina Estável/tratamento farmacológico , Fármacos Cardiovasculares/uso terapêutico , Angina Estável/cirurgia , Animais , Benzazepinas/uso terapêutico , Humanos , Ivabradina , Nicorandil/uso terapêutico , Intervenção Coronária Percutânea , Ranolazina/uso terapêutico , Trimetazidina/uso terapêutico
14.
World J Cardiol ; 6(9): 916-23, 2014 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-25276293

RESUMO

Apical hypertrophic cardiomyopathy (AHCM) is a relatively rare morphologic variant of HCM in which the hypertrophy of myocardium is localized to the left ventricular apex. Symptoms of AHCM might vary from none to others mimic coronary artery disease including acute coronary syndrome, thus resulting in inappropriate hospitalization. Transthoracic echocardiography is the first-line imaging technique for the diagnosis of hypertrophic cardiomyopathies. However, when the hypertrophy of the myocardium is localized in the ventricular apex might results in missed diagnosis. Aim of this paper is to review the different imaging techniques used for the diagnosis of AHCM and their role in the detection and comprehension of this uncommon disease.

15.
Cardiovasc Hematol Agents Med Chem ; 11(2): 101-5, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22963529

RESUMO

Platelets play a critical role in the pathogenesis of atherothrombotic processes and inhibition of platelet aggregation by antiplatelet therapy is essential and really important in the acute coronary syndromes or in the setting of percutaneous coronary intervention. The first family of adenosine diphosphate P2Y12 receptors inhibiting drug is represented by thienopyridines and among these ticlopidine was the first approved by Food and Drug Administration; actually its use is discouraged because of its potential side effects (neutropenia, anemia, gastrointestinal distress and thrombotic thrombocytopenic purpura). The second generation of thienopyridines is represented by clopidogrel that has replaced ticlopidine in the clinical practice; clopidogrel has the largest clinical experience. Prasugrel represents the third generation. It inhibits platelet aggregation by irreversibly blocking the adenosine diphosphate P2Y12 receptor. Ticagrelor, Cangrelor and Enilogrel represent the last generation of thienopyridines. This review is focused on the effects of adenosine diphosphate P2Y12 inhibitors.


Assuntos
Doenças Cardiovasculares/tratamento farmacológico , Antagonistas do Receptor Purinérgico P2Y/farmacologia , Antagonistas do Receptor Purinérgico P2Y/uso terapêutico , Humanos , Agregação Plaquetária/efeitos dos fármacos
16.
Int J Cardiol ; 161(1): 31-8, 2012 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-21722979

RESUMO

BACKGROUND: Most percutaneous recanalizations of coronary artery chronic total occlusion (CTO) are not attempted because of the skepticism on their long-term clinical benefit. We assessed the effect of percutaneous CTO recanalization procedures on long-term cardiac survival, freedom from MACE and angina-related quality of life (AQL). METHODS: All consecutive patients who underwent attempt of percutaneous native coronary artery CTO recanalization between 2003 and 2009 were included in the study. MACE was defined as combined cardiac death, myocardial infarction (MI) and target vessel revascularization (TVR). AQL was assessed by the Seattle Angina Questionnaire-UK-version (SAQ-UK). RESULTS: Among 302 patients who received an attempt of percutaneous CTO recanalization, 237 (78%) had a successful procedure while in 65 (22%) the procedure failed. Overall intra-hospital complication rate was 3.0%, with no difference between the two groups. Median follow-up was 4.0 years, during which 13 patients had a fatal cardiac event. Patients in whom the CTO recanalization procedure failed had a higher risk of cardiac death (HR 3.39; 95% CI 1.14-10.1;p=0.03; after propensity score adjustment, HR 2.83; 95% CI 0.89-8.96;p=0.07) and MACE (HR 5.40; 95% CI 2.71-10.5;p<0.001; adjusted HR 3.34; 95% CI 1.47-7.58;p=0.003) compared to patients with successful procedure. CTO recanalization significantly improved the AQL during follow-up: patients with successful procedure experienced less physical activity limitation (p=0.01), rarer angina episodes (p<0.001) and greater treatment satisfaction (p=0.03) compared to patients with failed procedure. CONCLUSIONS: Patients with successful CTO recanalization had a trend towards better cardiac survival and significant lower risk of MACE and improvement of AQL compared to patients with failed procedures.


Assuntos
Oclusão Coronária/mortalidade , Oclusão Coronária/cirurgia , Morte , Infarto do Miocárdio/prevenção & controle , Intervenção Coronária Percutânea , Qualidade de Vida , Idoso , Angioplastia Coronária com Balão/métodos , Doença Crônica , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/mortalidade , Intervenção Coronária Percutânea/métodos , Taxa de Sobrevida/tendências , Resultado do Tratamento
17.
J Invasive Cardiol ; 21(4): 145-50, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19342750

RESUMO

OBJECTIVES: We sought to evaluate clinical and angiographic outcomes of percutaneous coronary intervention (PCI) in patients receiving both bare-metal stents (BMS) and drug-eluting stents (DES). BACKGROUND: Few data are available about the safety and efficacy of the practice namely called "hybrid PCI". METHODS: One hundred and eighty-six patients, 502 de novo lesions, received during PCI both BMS (n = 266) and DES (316), with a mean of 3.1 +/- 1.2 stents/patient. Cumulative major adverse cardiac events were analyzed at 24 +/- 22 months. RESULTS: Clinical follow up was carried out in 100% of eligible patients. Angiographic follow up at 8.6 +/- 4.4 months was achieved in 70.4% of patients, 71.6% of stents and 72.5% of lesions. Binary restenosis was 12.9% vs. 20.6% (p = 0.034) in DES vs. BMS, respectively; late loss was significantly higher in BMS than in DES (0.67 +/- 0.73 vs. 0.35 +/- 0.71 mm; p < 0.001). DES showed less lumen loss and binary restenosis rates than BMS in B2/C lesions (p < 0.001 and 0.007, respectively), while any significant difference was detected in A/B1 lesions (p = 0.27 and 0.76, respectively). CONCLUSIONS: The simultaneous use of DES and BMS is safe and provides similar results for the 2 stents only in simple lesions. In complex lesions, BMS offer restenosis and a target lesion revascularization rates significantly higher than with DES.


Assuntos
Angioplastia Coronária com Balão , Angiografia Coronária , Doença da Artéria Coronariana/terapia , Vasos Coronários/patologia , Stents Farmacológicos/efeitos adversos , Abciximab , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticorpos Monoclonais/uso terapêutico , Anticoagulantes/uso terapêutico , Aspirina/uso terapêutico , Clopidogrel , Doença da Artéria Coronariana/tratamento farmacológico , Reestenose Coronária/prevenção & controle , Bases de Dados como Assunto , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos , Feminino , Heparina/uso terapêutico , Humanos , Fragmentos Fab das Imunoglobulinas/uso terapêutico , Masculino , Pessoa de Meia-Idade , Inibidores da Agregação Plaquetária/uso terapêutico , Estudos Retrospectivos , Stents/efeitos adversos , Ticlopidina/análogos & derivados , Ticlopidina/uso terapêutico , Fatores de Tempo , Resultado do Tratamento
18.
Catheter Cardiovasc Interv ; 73(2): 243-8, 2009 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-19156896

RESUMO

OBJECTIVES: We sought to evaluate the safety and performance of the Janus Tacrolimus-Eluting stent (TES) in an unselected population of patients, without application of restrictive clinical or angiographic criteria. BACKGROUND: Continued attention to the safety, efficacy, and deliverability of first-generation drug eluting stents has led to the development of new antiproliferative agents with alternative stent platforms and different drug carrier vehicles. METHODS: The TEST (Tacrolimus Eluting STent) registry is a prospective, nonrandomized single-center registry in which 140 consecutive patients who underwent single- or multi-vessel percutaneous coronary intervention between February 2005 and August 2005 were enrolled. RESULTS: The composite rate of major adverse cardiac events (MACE) at 22 months clinical follow-up was 40.9%. The rate of mortality, myocardial infarction, and target lesion revascularization (TLR) were 5.5%, 11%, and 31.5%, respectively. Angiographic follow-up at 8 months was achieved in 74% of patients; binary restenosis occurred in 39.4% of lesions. Most restenosis lesions (94.6%) had a diffuse pattern, while focal restenosis was observed in 5.4% of cases. Definite or probable stent thrombosis was observed in 2.4% of patients. CONCLUSIONS: The present prospective, nonrandomized, TEST registry indicated high MACE and restenosis rates, and thereby rather discouraging long-term outcomes with use of the Janus TES in an unselected "real world" population of patients who underwent single- or multi-vessel percutaneous coronary intervention.


Assuntos
Angioplastia Coronária com Balão/instrumentação , Fármacos Cardiovasculares/administração & dosagem , Angiografia Coronária , Reestenose Coronária/prevenção & controle , Estenose Coronária/terapia , Stents Farmacológicos , Infarto do Miocárdio/prevenção & controle , Tacrolimo/administração & dosagem , Idoso , Angioplastia Coronária com Balão/efeitos adversos , Angioplastia Coronária com Balão/mortalidade , Reestenose Coronária/diagnóstico por imagem , Reestenose Coronária/etiologia , Reestenose Coronária/mortalidade , Estenose Coronária/diagnóstico por imagem , Estenose Coronária/mortalidade , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/diagnóstico por imagem , Infarto do Miocárdio/etiologia , Infarto do Miocárdio/mortalidade , Estudos Prospectivos , Desenho de Prótese , Sistema de Registros , Medição de Risco , Fatores de Tempo , Resultado do Tratamento
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...