J. N. Gonçalves

Re-exploring the high-throughput potential of microextraction techniques, SPME and MEPS, as powerful strategies for medical diagnostic purposes. Innovative approaches, recent applications and future trends

AbstractThe human population continues to grow exponentially in the fast developing and most populated countries, whereas in Western Europe it is getting older and older each year. This inevitably raises the demand for better and more efficient medical services without increasing the economic burden in the same proportion. To meet these requirements, improvement of medical diagnosis is certainly a key aspect to consider. Therefore, we need powerful analytical methodologies able to go deeper and further in the characterization of human metabolism and identification of disease biomarkers and endogenous molecules in body fluids and tissues. The ultimate goal is to have a reliable and early medical diagnosis, mitigating the disease complications as much as possible. Microextraction techniques (METs) represent a key step in these analytical methodologies by providing samples in the suitable volumes and purification levels necessary for the characterization of the target analytes. In this aspect, solid-phase microextraction (SPME) and, more recently, microextraction by packed sorbent (MEPS), are powerful sample preparation techniques, characterized by their reduced time of analysis, low solvent consumption, and broad application. Moreover, as miniaturized techniques, they can be easily automatized to have a high-throughput performance in the clinical environment. In this review, we explore some of the most interesting MEPS and SPME applications, focusing on recent trends and applications to medical diagnostic, particularly the in vivo and near real time applications. FigureMETs as powerful strategies for medical diagnostic purposes

The QueuePusher: Enabling Queue Management in OpenFlow

The evolution of Software-Defined Networking and the overall acceptance of protocols such as OpenFlow, demonstrates the added value of decoupling the data plane from the control plane. Existing SDN Controllers enable the expected flexibility from such networks by dynamically providing a fine-grained control of each flow. However, hardware-specific configurations, such as the creation of queues or other mechanisms is out of the scope of these controllers. This work presents an extension to a well known OpenFlow controller (Floodlight) to efficiently handle the management of Traffic Control Queues in OpenFlow switches, resorting to a RESTful northbound interface. The obtained results demonstrate further possibility of developing innovative on-demand resource reservation mechanisms in SDN without adding unbearable overheads.

Implementing Quality of Service for the Software Defined Networking Enabled Future Internet

Achieving ever-growing Quality of Service (QoS) requirements for business customers is a major concern over the current Internet. However, presently, its architecture and infrastructures are inflexible to meet the demand of increased QoS requirements. OpenFlow, OF-Config (OpenFlow Configuration and Management protocol), and OVSDB (Open vSwitch Database Management protocol) protocols are well-known software defined networking (SDN) technologies for the Future Internet, enabling flexibility by decoupling the control plane from networking devices. In this paper, we propose a QoS framework using the SDN technologies and test the framework in failure-conditions using single and multiple autonomous system scenarios of the current Internet. We show that an effectively high QoS can be achieved for business customers using our framework.

Demonstrating Resilient Quality of Service in Software Defined Networking

Software defined Networking (SDN) such as Open-Flow decouples the control plane from forwarding devices and embeds it into one or more external entities called controllers. We implemented a framework in OpenFlow through which business customers receive higher Quality of Service (QoS) than best-effort customers in all conditions (e.g. failure conditions). In the demonstration, we stream video clips (business and best-effort customers traffic) through an emulated OpenFlow topology. During the demonstration, we trigger a failure in the paths of video clips and show an effectively higher QoS for business customers when compared against best-effort customers. This is demonstrated by simply watching the video clips at the receiver.

Unveiling the (De)coupling of magnetostructural transition nature in magnetocaloric R5Si2Ge2 (R 5Tb, Gd) materials

We present a detailed study on the magnetization under high magnetic fields of Tb5Si2Ge2 and Gd5Si2Ge2 compounds. From the Arrott plot construction (A. Arrott, Phys. Rev. 108, 1394 (1957)), we were able to estimate the TC of each structure (M and O(I)) experimentally and found that the TC of the O(I) phase can be directly obtained by extrapolating the TC curve of this phase in the respective phase diagram. Using a physical model based on free energy considerations, one explains the (de)coupling of the magnetic and structural transitions in R5(SixGe1−x)4 (R = Tb, Gd) compounds.

Ab-initio study of the relation between electric polarization and electric field gradients in ferroelectrics

The hyperfine interaction between the quadrupole moment of atomic nuclei and the electric field gradient (EFG) provides information on the electronic charge distribution close to a given atomic site. In ferroelectric materials, the loss of inversion symmetry of the electronic charge distribution is necessary for the appearance of the electric polarization. We present first-principles density functional theory calculations of ferroelectrics such as BaTiO3, KNbO3, PbTiO3 and other oxides with perovskite structures, by focusing on both EFG tensors and polarization. We analyze the EFG tensor properties such as orientation and correlation between components and their link with electric polarization. This work supports previous studies of ferroelectric materials where a relation between EFG tensors and polarization was observed, which may be exploited to study ferroelectric order when standard techniques to measure polarization are not easily applied.

Hyperfine local probe study of alkaline-earth manganites SrMnO3 and BaMnO3

We report perturbed angular correlation measurements with (111m)Cd/(111)Cd and (111)In/(111)Cd probes, at the ISOLDE-CERN facility, in the manganite compounds BaMnO3, with the 6H and 15R polymorphs, and SrMnO3, with the 4H polymorph. The electric field gradient (EFG) is measured, and found approximately constant in a large temperature range for all the compounds. The EFG is also calculated from first principles with density functional theory, and compared with experimental results by considering diluted substitutional Cd impurities. Based on the results, we assign as sites for the probes the Ba (for BaMnO3-6H, 15R) and Sr (for SrMnO3-4H) sites, apart from fractions of undetermined origin in the case of BaMnO3-6H. We predict the hyperfine parameters in the recently synthesized multiferroic manganite Sr(0.5)Ba(0.5)MnO3, and its variation with the structure and electric polarization, which is found to be very small.

Hyperfine interactions in MnAs studied by perturbed angular correlations of

conductivity changes is associated to magnetocaloric, magnetoelastic, and magnetoresistance effects. We report a study in a large temperature range from −196 ◦ up to 140 ◦ C, using the γ -γ perturbed angular correlations method with the radioactive probe 77 Br → 77 Se, produced at the On-Line Isotope Mass Separator (ISOLDE)-CERN facility. The electric field gradients and magnetic hyperfine fields are determined across the first- and second-order phase transitions encompassing the pure and mixed phase regimes in cooling and heating cycles. The temperature irreversibility of the first-order phase transition is seen locally at the nanoscopic scale sensitivity of the hyperfine field, by its hysteresis, detailing and complementing information obtained with macroscopic measurements (magnetization and X-ray powder diffraction). To interpret the results hyperfine parameters were obtained with first-principles spin-polarized density functional calculations using the generalized gradient approximation with the full potential (linear) augmented plane wave plus local orbitals method (WIEN2K code) by considering the Se probe at both Mn and As sites. A clear assignment of the probe location at the As site is made and complemented with the calculated densities of states and local magnetic moments. We model electronic and magnetic properties of the chemically similar MnSb and MnBi compounds, complementing previous calculations.

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Telemedicine as a communication technology to overcome geographical distances can increase the quality of medicine. The prerequisite for telemedicine is that two persons or groups of persons are connected with each other. Often this connection is built beforehand during a face-to-face-meeting when both partners apportion the communication devices. If an emergency patient is not already part of a telemedicine project, the connection has to be newly created and the device to build the connection has to be brought to the patient. In the EU-funded LiveCity-Project the hypothesis was evaluated, that in emergency situations a telemedicine connection between a patient and a remote medical doctor can be accomplished by a device brought to the patient by paramedics. It was to be established if communication with a head mounted video-camera coupled with a LTE internet connection was feasible for this purpose.

-rays using the probe

Ga2O3 bulk single crystals have been implanted with 300 keV Europium ions to fluences ranging from 1×1013 to 4×1015 at/cm2. The damage build-up and Eu-incorporation was assessed by Rutherford Backscattering Spectrometry in the channeling mode (RBS/C). RBS/C results suggest that implantation causes a mixture of defect clusters and extended defects such as dislocations. Amorphisation starts at the surface for fluences around 1×1015 at/cm2 and then proceeds to deeper regions of the sample with increasing fluence. Amorphous regions and defect clusters are efficiently removed during rapid thermal annealing at ~1100 °C; however, Eu diffuses towards the surface. Nevertheless, Eu ions are optically activated and show cathodoluminescence at room temperature. Results in bulk samples are compared to those in Eu-implanted Ga2O3 nanowires and despite strong similarities in the structural properties differences were found in the optical activation. Furthermore, damage and dopant incorporation studies were performed using the Perturbed Angular Correlation technique, which allows probing the immediate lattice surroundings of an implanted radioactive probe at the atomic level.