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A. A. Arenas, D. Di Luccio, S. Maggi, M. Palmisano, L. A. Salamanca Arévalo, R. A. M. Sanguino, A. Lay-Ekuakille
Geochemical characterization of heavy metals in the sediments of the sinú river (Colombia)

The presence of heavy metals in the superficial sediments of the Sinú River in Colombia was studied by analyzing soil samples taken along the course of the river at two different depths. Significant concentrations of several heavy metals were found in the samples as a function of the sample location and depth which may be related to the presence of intensive agricultural activities and mining plants in the region surrounding the sampling area. In particular, several sites showed high concentrations of nickel, cadmium and mercury, up to five times larger than the allowable safety limits.

M. López de Miguel, J. Pablo Salvador, F. Palacio, F. Arreza, A. Diéguez, J. D. Prades
Biodetection of environmental marine contaminants using regenerated biosensors: the irgarol case study

A low-cost and low-powered electro-mechanical device was designed and tested to perform a continuous monitoring tracking of sea contaminants. In particular, we focus our work on the biodetection of Irgarol, a specific seawater contaminant, selected as a proof-of-concept for the measurement system. The device based its measurement on a continuous analyte flow mode over the sensor cavity, followed by a sensor cleaning and regeneration process, which will prepare the sensor for the next measurement. All the system was designed to prioritize accuracy and repeatability.

A. Assaf, M. Zeghouane, J.-R. Plaussu, S. Cavalagliob, B. Pelissier, F. Bassani, I. Canero-Infante, T. Fiorido, M. Bendahan, S. Monfray, B. Salem, B. Vilquin, A. Souifi
Optimization of SnO2 thin films for low temperature NO2 sensors applications

In this work, a high-performance n-type semiconductor gas sensor based on undoped-SnO2 thin films deposited by a conventional radio- frequency (RF) – magnetron sputtering process was successfully fabricated. The structure, morphology, and chemical composition of the sensing material were investigated using X-ray diffraction (XRD), Atomic Force Microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) respectively. The end results show that the thin film has a poly- crystalline structure with the presence of oxygen vacancies. The resistive sensor architecture has been simulated using TCAD SILVACO software’s in order to optimize the geometry for sensor response optimization.
In this study, undoped-SnO2 resistive gas sensor exhibits compelling sensing performance for detecting 3 ppm of NO 2 mixed with dry air at low operating temperature, around 100°C. 3 ppm represents the maximum level of NO2 concentration beyond which short-term exposure presents a risk to human health or environmental degradation. Lower concentrations were also investigated in our study and the lowest NO2 concentration evaluated is about 0.25 ppm.

N. Khlifi, C. Zerrouki, N. Fourati, H. Guermazi, S. Guermazi
Indoped and Ni/Fe doped CuO nanoparticles: a structural, optical, and photocatalytic comparative study

The present work outlines the co-precipitation synthesis of undoped and -doped CuO NPs with two transition metals (TM), iron (Fe) and nickel (Ni), their characterization, and then their use as photocatalysts for the degradation of pollutants. The structural, morphological, and optical properties of the synthesized CuO NPs are characterized using X- ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and UV–Visible Diffused Reflectance Spectroscopy (DRS), techniques. The photocatalytic activities of the prepared oxide powders are evaluated against methylene blue (MB) taken as a model pollutant in aqueous media. The photodegradation efficiency is estimated and compared to other recent works.

T. Aloui, N. Fourati, H. Guermazi, C. Zerrouki, S. Guermazi
Hybrid adsorption and photocatalysis process for water treatment by nickel molybdate

Nickel molybdates were synthesized and tested in photocatalytic applications. Experiments conducted in the dark for one hour, showed a degradation efficiency of 44 % of methylene blue (MB), considered as a model pollutant. This high value was related to the strong adsorption of MB on the oxide particles, due to the synergistic effect of the 2D shape (revealed by scanning electron microscopy) developing a large surface area and their high roughness (estimated from atomic force microscopy measurements). Under visible light for one hour, the degradation efficiency reaches 87%, an improvement of almost 100 % compared to darkness. Attempts to regenerate and reuse nickel molybdate are made four times. The recovery process, which consists of washing particles only with distilled water, is encouraging enough even if not yet optimized.

F. Hauquier, C. Chapet, L. Dallery
3D printing technologies for electrochemical sensing: 17-alpha-ethinylestradiol detection

Monitoring of trace organic contaminants in aquatic media has become a major concern today. A 3D-printed device combined MIP-SPE extraction and electrochemical detection was developed for the determination of ethinyl estradiol (EE); one of endocrine-disrupting compounds (EDCs).
The proposed method was applied for the detection of EE in river water samples in order to monitor its concentration. A linear response was obtained for analyte in the concentration range from 6.6 to 1064 µg mL-1 , with a quantification limit of 20.0 µg mL-1.

A. Lay-Ekuakille, D. P. Bakajika Mukombo, John P. Djungha Okitadiowo, A. Nyengele, C. Lefi, C. Ntuala Ompua, M. Palmisano
Extracting vegetational features from landsat maps: using a delay and sum beamforming for image processing

Remote sensing has been performing a robust help in addressing issues related to extract information from satellite, and airborne-based platforms. This extraction is certainly a way for making quality and quantity analysis, hence measurements. This paper intends to illustrate the application of the delay and sum beamforming (DSB) approach to characterize satellite maps, in particular Landsat ones, for classifying different soil/land characteristics. The algorithm has been tested to detect the vegetation index from Lansat images of the city of Kinshasa (DR Congo). The DSB has demonstrated to exhibit better results than traditional techniques because of its accurate and reliable results.

FE. Dbibih, G. Fawaz, M. Vanotti, V. Soumann, V. Blondeau-Patissier
Innovative surface acoustic wave devices: a solution for real time monitoring and self-cleaning cascade impactor

This paper presents a comparative study of three types of surface acoustic waves sensors (SAW) used for particulate matter (PM) detection.
These sensors are placed in a cascade impactor as impaction plates. Monitoring their phase variation allows us to know the quantity of fine particles present in the environment with high accuracy. Until now, the sensors used in our prototype are built on quartz substrate and present a good sensitivity to fine particles. One major concern in our application is the fouling of the sensor’s surface with particles upon long periods of exposure. This shaped our drive to develop a self- cleaning sensor relying on other substrates with a stronger electromechanical coupling coefficient (K²). Hence, the aim of this study is to demonstrate the possibility of using strongly coupled piezoelectric substrates for an accurate PM detection as well as a self-cleaning process.

Thomas Siefke, Lauryna Siaudinyté, Søren Alkærsig Jensen, Astrid Tranum Rømer, Poul-Erik Hansen
Fine details of structural deviations in reference samples for scatterometry

In order to fulfil Moore’s law, the dimensions of the key elements of integrated circuits have been reduced to single digit nanometers. Besides enormous challenges for the micro- and nano fabrication methods itself, metrology is required for quality control to provide sub-nanometer uncertainties. Within the two EU founded projects ATMOC and POLight this challenge is tackled. In real world samples, deviations from the ideal geometries are encountered due to the complexities of fabrication processes. Understanding of these processes guides the development of procedures and helps in the reconstruction of the geometry from various scatterometric measurements. Here, we are reporting on the fabrication of reference samples for the mentioned projects and discuss the technological origins for such deviations.


Poul-Erik Hansen, Lauryna Siaudinyté, Thomas Siefke
In situ calibration of numerical aperture in optical microscopes

One of the most important components in microscopy is the illumination and imaging numerical aperture (NA). Together with the wavelength it sets the final limits and capabilities of the microscopy system. In scatterometry and ptychography a precise knowledge of the NA is required for the reconstruction algorithm. Here the uncertainty of values supplied by the manufactures are often to large, impairing the measurement capability of the system. In this research we demonstrate a method to measure the numerical aperture with high precision and thereby improve optical microscopy measurements.


Page 25 of 939 Results 241 - 250 of 9382