Hybrid magnetic graphitic nanocomposites for catalytic wet peroxide oxidation applications

Fe3O4, with a lattice parameter a = 8.357 A and average particle size of 12.5 +/- 3.6 nm, was successfully encapsulated within a graphitic structure by a hierarchical co-assembly approach, followed by thermal annealing. The resulting material was denoted as MGNC-magnetic graphitic nanocomposite. MGNC possesses average core size of 109 +/- 35 nm (mainly composed by agglomerates of magnetic nanoparticles), stability up to 400 degrees C under oxidizing atmosphere, a micro-mesoporous structure with a fairly developed specific surface area (S-BET = 330 m(2) g(-1)) and neutral character (pH(PZC) = 7.1). Catalytic wet peroxide oxidation (CWPO) experiments performed with a 4-nitrophenol (4-NP)/Fe3O4 mass ratio fixed at 36.6, allowed to achieve high efficiency of catalyst usage throughout the wide range of 4-NP concentration considered (200 mg L-1-5 g L-1). The inclusion of Fe3O4 nanoparticles in a graphitic structure during the synthesis of MGNC was found to (i) enhance the catalytic activity in CWPO when compared to Fe3O4, due to increased adsorptive interactions between the surface of the catalyst and the pollutant molecules, while (ii) strongly limiting the leaching of Fe species from Fe3O4 to the treated water, due to the confinement effect caused by the carbon shell. As a result of these effects, unprecedented pollutant mass removals were obtained ranging from 5000 mg(-1) h(-1), when the CWPO process is performed with [4-NP](o) = 200 mg L-1 at pH = 3, to 1250 mgg(-1) h(-1), when [4-NP](o) = 5 g L-1. High efficiency of H2O2 consumption is obtained when MGNC is applied in the CWPO of 4 -NP solutions at pH = 3, with TOC removals per unit of H2O2 decomposed (n(H2O2)) in the range 64-100%. In addition, the MGNC catalyst is also active at pH = 6; in this case a pollutant mass removal of 2090 mg g(-1) h(-1) was obtained. Although MGNC partially deactivates through successive reusability cycles, the pollutant mass removal obtained at the end of the fourth cycle is still very high when 200 mg L-1 4-NP solutions are considered (4808 mg g(-1) h(-1), representing only a ca. 4% decrease when compared to the first cycle). A higher deactivation of the MGNC catalyst is observed when 5 gL(-1) 4-NP solutions are employed. Nevertheless, the pollutant mass removal obtained at the end of the third cycle is still high (551 mgg(-1) h(-1))

Renal oncocytoma: Is URO-CT useful in histological diagnosis?

Introdução: Ao longo dos últimos anos, a crescente utilização de exames imagiológicos, nomeadamente ecografia e tomografia computorizada (TC), traduziu-se num aumento do diagnóstico incidental de tumores renais, sobretudo pequenas massas renais (<4 cm). O conhecimento de que até 30% destas massas podem ser benignas, entre elas os oncocitomas, levou á procura de métodos de diagnóstico mais eficazes, de forma a evitar situações de sobretratamento e de forma a tornaram-se decisões terapêuticas mais fundamentadas. Objectivos: Analisar retrospectivamente uma série de tumores renais histologicamente comprovados, nomeadamente oncocitomas e carcinomas de células renais (CCR), e verificar se existem diferenças morfológicas e/ou nos padrões de captação de contraste através da URO-TC. Material e métodos: Identificámos todos os tumores renais entre 2004-2015 com o diagnóstico histológico de oncocitoma e de CCR. Estes resultados foram obtidos por biopsia do tumor renal, tumorectomia/nefrectomia parcial ou nefrectomia radical. Registámos e comparámos as características morfológicas e os padrões de captação de contraste na fase nefrográfica com medição de unidades de Hounsfield (HU) dos oncocitomas e dos CCR (células claras), selecionados de acordo com a dimensão (aprox. idêntica á dos oncocitomas) e obtidos na sequência de tumorectomia renal ou nefrectomia radical. Resultados: Identificaram-se 16 CCR e 31 oncocitomas, dos quais 15 foram excluídos por não termos acesso ás imagens de TC no sistema informático. A dimensão média dos oncocitomas foi 3,7 cm (1,8 – 14) e a dos CCR 3,5 cm (1,9 – 8,4). A atenuação de contraste média dos oncocitomas e dos CCR na fase sem contraste foi de 33 HU e 32 HU, respectivamente. Na fase nefrográfica, a captação média de contraste para os oncocitomas foi de 47,5 HU e 47,4 HU para os CCR. Na fase nefrográfica, a diferença de atenuação entre os oncocitomas e o parênquima renal normal foi 43,5 HU e a diferença de atenuação entre os CCR e o parênquima renal normal foi 59,7 HU. Estes resultados foram estatisticamente significativos (p<0,05). Não se identificaram outras alterações na fase excretora da TC, nem diferenças relevantes de carácter morfológico, nomeadamente nos contornos das lesões, presença de calcificações, ou de cicatriz central. Conclusões: Na avaliação imagiológica por URO-TC, nomeadamente na fase nefrográfica, parece existir uma tendência para maior isodensidade dos oncocitomas em relação ao parênquima renal normal. Este achado poderá contribuir para uma melhor decisão terapêutica, na medida em que nos pode direccionar para uma biópsia de confirmação em detrimento da excisão cirúrgica.info:eu-repo/semantics/publishedVersio

Anomalous Breaking of Anisotropic Scaling Symmetry in the Quantum Lifshitz Model

In this note we investigate the anomalous breaking of anisotropic scaling symmetry in a non-relativistic field theory with dynamical exponent z=2. On general grounds, one can show that there exist two possible "central charges" which characterize the breaking of scale invariance. Using heat kernel methods, we compute these two central charges in the quantum Lifshitz model, a free field theory which is second order in time and fourth order in spatial derivatives. We find that one of the two central charges vanishes. Interestingly, this is also true for strongly coupled non-relativistic field theories with a geometric dual described by a metric and a massive vector field.Comment: 26 pages; major revision (results were unaffected), published versio

Imaging high-dimensional spatial entanglement with a camera

The light produced by parametric down-conversion shows strong spatial entanglement that leads to violations of EPR criteria for separability. Historically, such studies have been performed by scanning a single-element, single-photon detector across a detection plane. Here we show that modern electron-multiplying charge-coupled device cameras can measure correlations in both position and momentum across a multi-pixel field of view. This capability allows us to observe entanglement of around 2,500 spatial states and demonstrate Einstein-Podolsky-Rosen type correlations by more than two orders of magnitude. More generally, our work shows that cameras can lead to important new capabilities in quantum optics and quantum information science.Comment: 5 pages, 4 figure

Enzymatic degradation of starch thermoplastic blends using samples of different thickness

The material studied was a thermoplastic blend of corn starch with a poly(ethylene-vinyl alcohol) copolymer, SEVA-C. The influence of both the material’s exposed surface and enzyme concentration on degradation kinetics was studied. As α-amylase is present in the blood plasma, experiments were performed, varying the material thickness and the α-amylase between 50 and 100 units/l, at 37°C, lasting up to 90 days. Four different batches using SEVA-C and starch samples of different thickness were performed. The positive correlation between degradation rate and the exposed material surface was confirmed, since thin films with larger exposed surfaces were degraded faster than thick square plates having the same total mass. The degradation extent depends on the total amount of amorphous starch present in the formulation rather than on the amount of enzyme used and the minimum thickness to ensure maximum degradation was estimated to be close to 0.25 mm

Obstacle Avoidance Using Echo Sounder Sonar

Developing obstacle avoidance algorithms for low cost Autonomous Underwater Vehicles using single beam returned echo sounder sonar is a difficult task. In this paper, we propose an intelligent obstacle avoidance algorithm that maps the obstacle, avoids it with a guarantee that it will not get stuck and efficiently traverses a path towards the destination using navigation functions. We present a complete obstacle avoidance system with the help of hybrid automata, probabilistic mapping and navigation functions. Simulation results are presented showing the validity of our approach

Supercritical phase inversion of starch-poly(e-caprolactone) for tissue engineering applications

In this work, a starch-based polymer, namely a blend of starch-poly(ε-caprolactone) was processed by supercritical assisted phase inversion process. This processing technique has been proposed for the development of 3D structures with potential applications in tissue engineering applications, as scaffolds. The use of carbon dioxide as non-solvent in the phase inversion process leads to the formation of a porous and interconnected structure, dry and free of any residual solvent. Different processing conditions such as pressure (from 80 up to 150 bar) and temperature (45 and 55°C) were studied and the effect on the morphological features of the scaffolds was evaluated by scanning electron microscopy and micro-computed tomography. The mechanical properties of the SPCL scaffolds prepared were also studied. Additionally, in this work, the in vitro biological performance of the scaffolds was studied. Cell adhesion and morphology, viability and proliferation was assessed and the results suggest that the materials prepared are allow cell attachment and promote cell proliferation having thus potential to be used in some for biomedical applications.Ana Rita C. Duarte is grateful for financial support from Fundacao para a Ciencia e Tecnologia through the grant SFRH/BPD/34994/2007

Cost-effectiveness analysis of 3-D computerized tomography colonography versus optical colonoscopy for imaging symptomatic gastroenterology patients.

BACKGROUND: When symptomatic gastroenterology patients have an indication for colonic imaging, clinicians have a choice between optical colonoscopy (OC) and computerized tomography colonography with three-dimensional reconstruction (3-D CTC). 3-D CTC provides a minimally invasive and rapid evaluation of the entire colon, and it can be an efficient modality for diagnosing symptoms. It allows for a more targeted use of OC, which is associated with a higher risk of major adverse events and higher procedural costs. A case can be made for 3-D CTC as a primary test for colonic imaging followed if necessary by targeted therapeutic OC; however, the relative long-term costs and benefits of introducing 3-D CTC as a first-line investigation are unknown. AIM: The aim of this study was to assess the cost effectiveness of 3-D CTC versus OC for colonic imaging of symptomatic gastroenterology patients in the UK NHS. METHODS: We used a Markov model to follow a cohort of 100,000 symptomatic gastroenterology patients, aged 50 years or older, and estimate the expected lifetime outcomes, life years (LYs) and quality-adjusted life years (QALYs), and costs (£, 2010-2011) associated with 3-D CTC and OC. Sensitivity analyses were performed to assess the robustness of the base-case cost-effectiveness results to variation in input parameters and methodological assumptions. RESULTS: 3D-CTC provided a similar number of LYs (7.737 vs 7.739) and QALYs (7.013 vs 7.018) per individual compared with OC, and it was associated with substantially lower mean costs per patient (£467 vs £583), leading to a positive incremental net benefit. After accounting for the overall uncertainty, the probability of 3-D CTC being cost effective was around 60 %, at typical willingness-to-pay values of £20,000-£30,000 per QALY gained. CONCLUSION: 3-D CTC is a cost-saving and cost-effective option for colonic imaging of symptomatic gastroenterology patients compared with OC