Abstract
We present a portable and low-cost system for interrogation of long-period fiber gratings (LPFGs) costing around a 30th of the price of a typical setup using an optical spectrum analyzer and a broadband light source. The unit is capable of performing real-time monitoring or as a stand-alone data-logger. The proposed technique uses three thermally modulated fiber-coupled laser diodes, sweeping a few nanometers around their central wavelength. The light signal is then modulated by the LPFG and its intensity is acquired by a single photo-detector. Through curve-fitting algorithms the sensor transmission spectrum is reconstructed. Testing and validation were accomplished by inducing variations in the spectral features of an LPFG through changes either in external air temperature from 22 to 425 degrees C or in refractive index (RI) of the surrounding medium from 1.3000 to 1.4240. A dynamic resolution between 3.5 and 1.9 degrees C was achieved, in temperatures from 125 to 325 degrees C. In RI measurements, maximum wavelength and optical power deviations of 2.75 nm and 2.86 dB, respectively, were obtained in the range from 1530 to 1570 nm. The worse RI resolution obtained was 3.47x10(-3). The interrogation platform was then applied in the detection of iron corrosion, expressing wavelength peak values within 1.12 nm from the real value in the region between 1530 and 1570 nm.

Abstract
In view of the growing importance of nanotechnologies, the detection of nanoparticles type in several contexts has been considered a relevant topic. Several organisms, including the National Institutes of Health, have been highlighting the urge of developing nanoparticles exposure risk assessment assays, since very little is known about their physiological responses. Although the identi fi cation/characterization of synthetically produced nanoparticles is considered a priority, there are many examples of \ naturally" generated nanostructures that provide useful information about food components or human physiology. In fact, several nanoscale extracellular vesicles are present in physiological fluids with high potential as cancer biomarkers. However, scientists have struggled to fi nd a simple and rapid method to accurately detect/identify nanoparticles, since their majority have diameters between 100-150 nm -far below the di ff raction limit. Currently, there is a lack of instruments for nanoparticles detection and the few instrumentation that is commonly used is costly, bulky, complex and time consuming. Thus, considering our recent studies on particles identi fi cation through back-scattering, we examined if the time/frequency-domain features of the back-scattered signal provided from a 100 nm polystyrene nanoparticles suspension are able to detect their presence only by dipping a polymeric lensed optical fi ber in the solution. This novel technique allowed the detection of synthetic nanoparticles in distilled water versus \ blank solutions" (only distilled water) through Multivariate Statistics and Arti fi cial Intelligence (AI)-based techniques. While the state-of-the-art methods do not o ff er a ff ordable and simple approaches for nanoparticles detection, our technique can contribute for the development of a device with innovative characteristics.

Abstract
A femtosecond laser direct writing system was developed to explore the fabrication of long-period fiber gratings (LPFGs) in SMF28 fibers. The LPFGs, showing the mode LP1,6 at 1500 nm, were exposed to high-temperature annealing up to 950 °C. Modifications in the refractive index (RI) modulation are observed through a blue-shift in the LPFG attenuation bands and above 850 °C, the mode LP1,7 appear at 1600 nm. The wavelength sensitivity to external RI from 1.300 to 1.452 was estimated for both modes before and after annealing. Greater sensitivity was found for the higher order mode in the entire range reaching 2400 nm/RIU around 1.440.

Abstract
The wavelength sensitivity and spectral resolution of Mach-Zehnder fiber interferometers obtained through a combination of two identical uncoated and titanium dioxide (TiO2) coated long period fiber gratings (LPFGs) is presented and compared with single LPFGs-based refractometric sensors. A set of LPFGs were fabricated in single mode fiber with the resonance band having an amplitude of 3 dB in order to split in half the optical power between the core and the specific cladding modes. The separation between the pair of LPFG written in the fiber was varied between 1 and 3 cm and the thickness of the TiO2 coating around the fiber ranged from 20 to 40 nm. A wavelength shift sensitivity of 216 nm/refractive index units (RIU) was achieved for the device with 3 cm and a 30-nm thick TiO2 coating, which presented a spectral resolution of 1.1 x 10(-4 )Rill Despite the lower wavelength shift sensitivity of 142 nm/RIU, attained for a 2-cm long device and 30-nm thick TiO2 coating, a spectral resolution of 1.8 x 10(-5) RIU was measured, which is one order of magnitude lower than a single LPFG.

Abstract
In the last few decades, the alkali-silica reaction (ASR) has been reported as one of the major concrete concerns regarding durability, leading to high maintenance and reconstruction costs. The occurrence of ASR in numerous concrete infrastructures all over the world points to the need for research regarding measures for its detection in an initial stage (and further mitigation) either in new or existing structures. Furthermore, the chemical and physical mechanisms for ASR remain poorly understood. This lack of knowledge leads to incapacity to assess risk, cost-effectively predict service life, and efficiently mitigate the deterioration process due to ASR in concrete structures. This manuscript aims to review the most recent and relevant achievements and the existing knowledge concerning the reaction mechanisms of ASR. Additionally, this manuscript is focused on the conditioning factors, diagnostic and prognostic methodologies, preventive measures and test methods (including their limitations) of ASR conducted at an academic level. The perspectives for future research challenges are also identified and debated.

Abstract
Metabolomics is paramount for precision agriculture. Knowing the metabolic state of the vine and its implication for grape quality is of outermost importance for viticulture and wine industry. The MetBots system is a metabolomics precision agriculture platform, for automated monitoring of vineyards, providing geo-referenced metabolic images that are correlated and interpreted by an artificial intelligence self-learning system for aiding precise viticultural practices. Results can further be used to analyze the plant metabolic response by genome-scale models. In this research, we introduce the system main components: (i) robotic platform; (ii) autonomous navigation; (iii) sampling arm manipulation; (iv) spectroscopy systems; and (v) non-invasive, real-time metabolic hyper-spectral imaging monitoring of vineyards. The full potential of the Metbots system is revealed when metabolic data and images are analyzed by big data AI and systems biology vine plant models, establishing a new age of molecular biology precision agriculture. © Springer Nature Switzerland AG 2019.