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5.
Dalton Trans ; 49(2): 274-278, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31803888

RESUMO

The industrial fluorination of UO2 to UF4 is based on a complex process involving the manipulation of a large amount of HF, a very toxic and corrosive gas. We present here a safer way to accomplish this reaction utilizing ionic liquid [Bmim][PF6] as a unique reaction medium and fluoride source.

9.
MAGMA ; 32(2): 269-279, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30171383

RESUMO

PURPOSE: With the hypothesis that 4D flow can be used in evaluation of cardiac shunts, we seek to evaluate the multilevel and interreader reproducibility of measurements of the blood flow, shunt fraction and shunt volume in patients with atrial septum defect (ASD) in practice at multiple clinical sites. MATERIALS AND METHODS: Four-dimensional flow MRI examinations were performed at four institutions across Europe and the US. Twenty-nine patients (mean age, 43 years; 11 male) were included in the study. Flow measurements were performed at three levels (valve, main artery and periphery) in both the pulmonary and systemic circulation by two independent readers and compared against stroke volumes from 4D flow anatomic data. Further, the shunt ratio (Qp/Qs) was calculated. Additionally, shunt volume was quantified at the atrial level by tracking the atrial septum. RESULTS: Measurements of the pulmonary blood flow at multiple levels correlate well whether measuring at the valve, main pulmonary artery or branch pulmonary arteries (r = 0.885-0.886). Measurements of the systemic blood flow show excellent correlation, whether measuring at the valve, ascending aorta or sum of flow from the superior vena cava (SVC) and descending aorta (r = 0.974-0.991). Intraclass agreement between the two observers for the flow measurements varies between 0.96 and 0.99. Compared with stroke volume, pulmonic flow is underestimated with 0.26 l/min at the main pulmonary artery level, and systemic flow is overestimated with 0.16 l/min at the ascending aorta level. Direct measurements of ASD flow are feasible in 20 of 29 (69%) patients. CONCLUSION: Blood flow and shunt quantification measured at multiple levels and performed by different readers are reproducible and consistent with 4D flow MRI.


Assuntos
Técnicas de Imagem Cardíaca/métodos , Comunicação Interatrial/diagnóstico por imagem , Comunicação Interatrial/fisiopatologia , Imagem por Ressonância Magnética/métodos , Adulto , Velocidade do Fluxo Sanguíneo , Técnicas de Imagem Cardíaca/estatística & dados numéricos , Feminino , Comunicação Interatrial/classificação , Humanos , Imageamento Tridimensional/métodos , Imageamento Tridimensional/estatística & dados numéricos , Imagem por Ressonância Magnética/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Estudos Prospectivos , Circulação Pulmonar , Reprodutibilidade dos Testes , Estudos Retrospectivos , Volume Sistólico
11.
Phys Chem Chem Phys ; 20(24): 16770-16776, 2018 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-29888355

RESUMO

Radioactive gaseous ruthenium tetroxide (RuO4) can be released into the environment in the case of a severe nuclear accident. Using periodic dispersion corrected density functional theory calculations, we have investigated for the first time the adsorption behavior of RuO4 into prototypical porous materials, Metal-Organic Frameworks (MOFs) and zeolites, with the aim of mitigating ruthenium releases to the outside. For the MOFs, we have screened a set of six structures (MIL-53(Al), MIL-120(Al), HKUST-1(Cu), UiO-66(Zr), UiO-67(Zr) and UiO-68(Zr)), while for the zeolites two structures have been selected: mordenite (MOR) with Si/Al ratios of 11 and 5, and faujasite (FAU) with a Si/Al ratio of 2.4. The DFT calculations show that the nature of the porous materials does not have a significant effect on the adsorption energy of RuO4 compounds and that the main interaction is due to the formation of hydrogen bonds. For the tested materials, computational results show that the interaction energies of RuO4 reach their maximum with the hydrated form of HKUST-1(Cu) (-114 kJ mol-1) due to the presence of strong hydrogen bonds between the water molecules and the oxygen atoms of RuO4.

12.
Int J Cardiovasc Imaging ; 34(8): 1249-1263, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29556943

RESUMO

Non-invasive imaging plays a growing role in the diagnosis and management of ischemic heart disease from its earliest manifestations of endothelial dysfunction to myocardial infarction along the myocardial ischemic cascade. Experts representing the North American Society for Cardiovascular Imaging and the European Society of Cardiac Radiology have worked together to organize the role of non-invasive imaging along the framework of the ischemic cascade. The current status of non-invasive imaging for ischemic heart disease is reviewed along with the role of imaging for guiding surgical planning. The issue of cost effectiveness is also considered. Preclinical disease is primarily assessed through the coronary artery calcium score and used for risk assessment. Once the patient becomes symptomatic, other imaging tests including echocardiography, CCTA, SPECT, PET and CMR may be useful. CCTA appears to be a cost-effective gatekeeper. Post infarction CMR and PET are the preferred modalities. Imaging is increasingly used for surgical planning of patients who may require coronary artery bypass.


Assuntos
Técnicas de Imagem Cardíaca/métodos , Doença da Artéria Coronariana/diagnóstico por imagem , Isquemia Miocárdica/diagnóstico por imagem , Angina Pectoris/diagnóstico por imagem , Técnicas de Imagem Cardíaca/economia , Doença da Artéria Coronariana/complicações , Doença da Artéria Coronariana/cirurgia , Análise Custo-Benefício , Progressão da Doença , Endotélio Vascular/diagnóstico por imagem , Humanos , Infarto do Miocárdio/diagnóstico por imagem , Infarto do Miocárdio/etiologia , Isquemia Miocárdica/etiologia
14.
Phys Chem Chem Phys ; 19(40): 27530-27543, 2017 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-28976509

RESUMO

Radioactive iodine species belong to the most dangerous components of nuclear effluents and waste produced by nuclear facilities. In this work, we use computer simulations at the periodic DFT level to investigate dissociative adsorption of iodomethane on silver-exchanged mordenite, which is among the most effective sorbents of iodine species available today. The structure, energetics, and mobility of complexes Ag-(CH3I) and Ag-(CH3I)2 formed upon adsorption of iodomethane on Ag+ sites are investigated using the ab initio MD approach. The free-energy profiles for the reaction CH3I + Ag-MOR → AgI + CH3-MOR are determined using the blue moon ensemble technique. The AgI species formed as a product of dissociative adsorption are shown to combine spontaneously into small clusters (AgI)n with the dimensions restricted by the size and geometry of confining voids. The structure and energetics of the (AgI)n species are analysed in detail and compared with the available experimental and theoretical data. The internal energy of formation of clusters in mordenite is shown to contribute significantly to the shift of equilibrium from the undissociated to dissociated form of adsorbed CH3I.

18.
Eur Radiol ; 27(2): 821-830, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27271922

RESUMO

OBJECTIVES: To demonstrate non-inferiority of iobitridol 350 for coronary CT angiography (CTA) compared to higher iodine content contrast media regarding rate of patients evaluable for the presence of coronary artery stenoses. METHODS: In this multicentre trial, 452 patients were randomized to receive iobitridol 350, iopromide 370 or iomeprol 400 and underwent coronary CTA using CT systems with 64-detector rows or more. Two core lab readers assessed 18 coronary segments per patient regarding image quality (score 0 = non diagnostic to 4 = excellent quality), vascular attenuation, signal and contrast to noise ratio (SNR, CNR). Patients were considered evaluable if no segment had a score of 0. RESULTS: Per-patient, the rate of fully evaluable CT scans was 92.1, 95.4 and 94.6 % for iobitridol, iopromide and iomeprol, respectively. Non-inferiority of iobitridol over the best comparator was demonstrated with a 95 % CI of the difference of [-8.8 to 2.1], with a pre-specified non-inferiority margin of -10 %. Although average attenuation increased with higher iodine concentrations, average SNR and CNR did not differ between groups. CONCLUSIONS: With current CT technology, iobitridol 350 mg iodine/ml is not inferior to contrast media with higher iodine concentrations in terms of image quality for coronary stenosis assessment. KEY POINTS: • Iodine concentration is an important parameter for image quality in coronary CTA. • Contrast enhancement must be balanced against the amount of iodine injected. • Iobitridol 350 is non-inferior compared to CM with higher iodine concentrations. • Higher attenuation with higher iodine concentrations, but no SNR or CNR differences.


Assuntos
Calcinose/diagnóstico por imagem , Angiografia por Tomografia Computadorizada/métodos , Angiografia Coronária/métodos , Estenose Coronária/diagnóstico por imagem , Adulto , Idoso , Meios de Contraste , Doença da Artéria Coronariana/diagnóstico por imagem , Método Duplo-Cego , Feminino , Humanos , Iodo , Iohexol/análogos & derivados , Iopamidol/análogos & derivados , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada Multidetectores/métodos , Tomografia Computadorizada por Raios X/métodos
19.
Phys Chem Chem Phys ; 18(48): 33282-33286, 2016 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-27896341

RESUMO

The energetics of the catalytic oxidation of CO on a complex metal oxide are investigated for the first time via density functional theory calculations. The catalyst, Co-doped SrTiO3, is modelled using periodically repeated slabs based on the SrTiO3(100) surface. The comparison of the energy profiles obtained for the pure host and the Co-doped material reveals the actual pathway followed by the reaction, and shows that Co doping enhances the catalytic properties of SrTiO3 by reducing the energy cost for the formation of oxygen vacancies.

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