Abstract
A sensing configuration for the real-time monitoring, detection, and quantification of dissolved carbon dioxide (dCO(2)) was developed for aquaculture and other applications in freshwater and saline water. A chemical sensing membrane, based on a colorimetric indicator, is combined with multimode optical fiber and a dual wavelength light-emitting diode (LED) to measure the dCO(2)-induced absorbance changes in a self-referenced ratiometric scheme. The detection and processing were achieved with an embeded solution having a mini spectrometer and microcontroller. For optrode calibration, chemical standard solutions using sodium carbonate in acid media were used. Preliminary results in a laboratory environment showed sensitivity for small added amounts of CO2 (0.25 mg.L-1). Accuracy and response time were not affected by the type of solution, while precision was affected by salinity. Calibration in freshwater showed a limit of detection (LOD) and a limit of quantification (LOQ) of 1.23 and 1.87 mg.L-1, respectively. Results in saline water (2.5%) showed a LOD and LOQ of 1.05 and 1.16 mg.L-1, respectively. Generally, performance was improved when moving from fresh to saline water. Studies on the dynamics of dissolved CO2 in a recirculating shallow raceway system (SRS+RAS) prototype showed higher precision than the tested commercial sensor. The new sensor is a compact and robust device, and unlike other sensors used in aquaculture, stirring is not required for correct and fast detection. Tests performed showed that this new sensor has a fast accurate detection as well as a strong potential for assessing dCO(2) dynamics in aquaculture applications.

Abstract
High concentration of biogenic amines (BA) is an indicator of deterioration of food and the determination of their concentration is an important method of food control. The hydrogen peroxide (H2O2) is a side product of the degradation of BAs by certain enzymes. It is presented an experimental technique grounded on chemiluminescence to measure small quantities of H2O2 with concentrations as low as 0.01%w/w up to 0.08%w/w. Luminol and cobalt hydroxide are added to hydroxyethyl cellulose to obtain an active membrane which will react with the sampling solution and the amount of total light emission is directly related to the H2O2 concentration.

Abstract
A high-resolution advanced laser induced breakdown spectroscopy prototype was used to quantify lithium (Li) in lithiniferous rocks. Samples were collected from Barroso's mine (Portugal), claimed as Western Europe's largest spodumene Li discovery. 51 samples from a reverse circulation drill were collected, one for each meter interval, dried, milled, pressed into pellets and further analyzed by laser induced breakdown spectroscopy. Quantification was attempted using either linear models based on the intensity of selected Li spectral lines or advanced chemometrics methods. The latter was very successful, with correlation coefficients of 0.97 against certified laboratory results.

Abstract
A femtosecond laser direct writing system was developed to explore the fabrication of periodic structures in optical fibers. The possibility to write type I first- and second-order Bragg gratings in the same single-mode fiber (SMF-28e), with reflectivities of 99.6 % and 59.3 %, respectively, is presented. The fabrication of structures (waveguides and grating) in a coreless and in a SMF-28e fiber was first demonstrated, and the gratings were then exposed to a thermal annealing up to 1000 degrees C. The FBG inscribed in the SMF-28e fiber presents thermal stability at temperatures of 800 degrees C and a temperature sensitivity of 14.34 pm/degrees C was determined.

Abstract
A low-computational intensive laser control approach is proposed for implementing an embedded control system, using pattern recognition by relevant principal component analysis for laser induced breakdown spectroscopy applications. The laser energy is directly related to the resulting spectral pattern and is determined by iterations in the feature space. Results show that single shot iterations until optimum energy can be significantly reduced by pattern recognition. A performance benchmark with minerals, alloys and pellets from material collected from a drill demonstrated an average of 50% improvement, significantly reducing sample deterioration and improving measurement safety.

Abstract
Dissolved carbon dioxide (dCO2) evaluation is very important in many different fields. In this work, a new, integrated, colorimetric-optical fiber-based system for dCO2 monitoring in aquaculture industry was developed. The sensing chemistry is based on colorimetric changes of the used indicator—poly p-nitrophenol (pNPh)—in contact with CO2. Preliminary tests were done in a laboratory environment (calibration) and in a laboratory Recirculating Aquaculture System (RAS) with controlled CO2 injection. The results have shown the suitability of the new sensor for assessing dCO2 dynamics in RAS and its fast detection of low dCO2 concentrations in an appropriate operation range.