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Publications

Publications by CAP

2017

Structural, morphological, ionic conductivity, and thermal properties of pectin-based polymer electrolytes

Authors
Mendes, JP; Esperanca, JMSS; Medeiros, MJ; Pawlicka, A; Silva, MM;

Publication
MOLECULAR CRYSTALS AND LIQUID CRYSTALS

Abstract
New polymer electrolytes (PEs), potentially interesting for solid-state electrochemical devices applications, were synthesized by a solvent casting method using pectin and ionic liquid (IL) N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium bis(trifluoromethylsulfonyl)imide ([N-1 1 1 2(OH)] [NTf2]. The resulting electrolytes besides being moderately homogenous and thermally stable below 155 degrees C, they also exhibited good mechanical properties. The SPE membranes were analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and complex impedance spectroscopy.

2017

Assessing arsenic and selenium in a single nail clipping using portable X-ray fluorescence

Authors
Fleming, DEB; Nader, MN; Foran, KA; Groskopf, C; Reno, MC; Ware, CS; Tehrani, M; Guimaraes, D; Parsons, PJ;

Publication
APPLIED RADIATION AND ISOTOPES

Abstract
The feasibility of measuring arsenic and selenium contents in a single nail clipping was investigated using a small-focus portable X-ray fluorescence (XRF) instrument with monochromatic excitation beams. Nail clipping phantoms supplemented with arsenic and selenium to produce materials with 0, 5, 10, 15, and 20 mu g/g were used for calibration purposes. In total, 10 different clippings were analyzed at two different measurement positions. Energy spectra were fit with detection peaks for arsenic K-alpha, selenium K-alpha, arsenic K-beta, selenium K-beta, and bromine K-alpha characteristic X-rays. Data analysis was performed under two distinct conditions of fitting constraint. Calibration lines were established from the amplitude of each of the arsenic and selenium peaks as a function of the elemental contents in the clippings. The slopes of the four calibration lines were consistent between the two conditions of analysis. The calculated minimum detection limit (MDL) of the method, when considering the Ka peak only, ranged from 0.210 +/- 0.002 mu g/g selenium under one condition of analysis to 0.777 +/- 0.009 mu g/g selenium under another. Compared with previous portable XRF nail clipping studies, MDLs were substantially improved for both arsenic and selenium. The new measurement technique had the additional benefits of being short in duration (similar to 3 min) and requiring only a single nail clipping. The mass of the individual clipping used did not appear to play a major role in signal strength, but positioning of the clipping is important.

2017

Preparation and biological evaluation of ethionamide-mesoporous silicon nanoparticles against Mycobacterium tuberculosis

Authors
Vale, N; Correia, A; Silva, S; Figueiredo, P; Makila, E; Salonen, J; Hirvonen, J; Pedrosa, J; Santos, HA; Fraga, A;

Publication
BIOORGANIC & MEDICINAL CHEMISTRY LETTERS

Abstract
Ethionamide (ETH) is an important second-line antituberculosis drug used for the treatment of patients infected with multidrug-resistant Mycobacterium tuberculosis. Recently, we reported that the loading of ETH into thermally carbonized-porous silicon (TCPSi) nanoparticles enhanced the solubility and permeability of ETH at different pH-values and also increased its metabolization process. Based on these results, we synthesized carboxylic acid functionalized thermally hydrocarbonized porous silicon nanoparticles (UnTHCPSi NPs) conjugated with ETH and its antimicrobial effect was evaluated against Mycobacterium tuberculosis strain H37Rv. The activity of the conjugate was increased when compared to free-ETH, which suggests that the nature of the synergy between the NPs and ETH is likely due to the weakening of the bacterial cell wall that improves conjugate-penetration. These ETH-conjugated NPs have great potential in reducing dosing frequency of ETH in the treatment of multidrug-resistant tuberculosis (MDR-TB).

2017

Fabry-Perot cavity based on air bubble for high sensitivity lateral load and strain measurements

Authors
Novais, S; Ferreira, MS; Pinto, JL;

Publication
THIRD INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
A Fabry-Perot air bubble microcavity fabricated between a section of single mode fiber and a multimode fiber is proposed. The study of the microcavities growth with the number of applied arcs is performed. The sensors are tested for lateral load and strain, where sensitivities of 0.32 nm/N and 2.11 nm/N and of 4.49 pm/mu epsilon and 9.12 pm/mu epsilon are obtained for the 47 mu m and 161 mu m long cavities, respectively. The way of manufacturing using a standard fusion splicer and given that no oils or etching solutions are involved, emerges as an alternative to the previously developed air bubble based sensors.

2017

Lateral Load Sensing With an Optical Fiber Inline Microcavity

Authors
Novais, S; Ferreira, MS; Pinto, JL;

Publication
IEEE PHOTONICS TECHNOLOGY LETTERS

Abstract
A Fabry-Perot air bubble microcavity fabricated between a section of single mode fiber and a multimode fiber that requires only the use of a commercial fusion splicer is proposed. The study of the microcavities growth with the number of applied arcs is performed and several sensors are tested. The sensors are tested for lateral load measurements, and it is observed that there is dependence between the sensor dimensions and its sensitivity. The maximum sensitivity of 2.11 nm/N was obtained for the 161-mu m-long cavity. Moreover, given the low temperature sensitivity (<1 pm/degrees C), the proposed cavity should be adequate to perform temperature-independent measurements. The accurate technique control leads to the fabrication of reproducible cavities with the sensitivity required for the application. The way of manufacturing using a standard fusion splicer, given that no oils or etching solutions are involved, emerges as an alternative to the previously developed air bubble-based sensors.

2016

Aptamer-based fiber sensor for thrombin detection

Authors
Coelho, L; Marques Martins de Almeida, JMM; Santos, JL; da Silva Jorge, PAD; Martins, MCL; Viegas, D; Queiros, RB;

Publication
JOURNAL OF BIOMEDICAL OPTICS

Abstract
The detection of thrombin based on aptamer binding is studied using two different optical fiber-based configurations: long period gratings coated with a thin layer of titanium dioxide and surface plasmon resonance devices in optical fibers coated with a multilayer of gold and titanium dioxide. These structures are functionalized and the performance to detect thrombin in the range 10 to 100 nM is compared in transmission mode. The sensitivity to the surrounding refractive index (RI) of the plasmonic device is higher than 3100 nmRIU(-1) in the RI range 1.335 to 1.355, a factor of 20 greater than the sensitivity of the coated grating. The detection of 10 nM of thrombin was accomplished with a wavelength shift of 3.5 nm and a resolution of 0.54 nM. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)

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