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A. Adiraju, A. Al-Hamry, O. Kanoun
Finite element method based investigation of substrates effect on surface-enhanced Raman spectroscopy

Surface-enhanced Raman spectroscopy (SERS) is a widely used method for the detection of molecules of environmental concern such as pesticides. One of the key factors to achieve high sensitivity in SERS is the high electromagnetic enhancement formed between plasmonic nanoparticles which is dependent on the wavelength used, shape, size, distance, and type of nanoparticles. In this regard, the scope of this paper is to investigate the enhancement factor achieved between adjacent silver or gold nanoparticles of different geometrical configurations by changing the shapes and sizes of the particles. Simulations based on finite element methods (FEM) were carried out to investigate the effect of different excitation laser wavelengths. The obtained results show the dependency of the enhancement factor, size, type of nanoparticles, excitation wavelength of the laser, dielectric properties of the surrounding medium and the type of substrate used.

V. Elias, A. Rabih, F. Braud, P. Champagne, G. Nassar
The cantilever micro-beam behavior for environment check

In this paper, a new model of a vibrating micro- cantilever is presented, which can be heavily utilized in a microelectromechanical system (MEMS). With our new prototype, several risks associated with the previous means are eliminated, and the rheological sensation is enhanced. The cantilever beam is made out of silicon (Si) engraved by a laser etching machine in an exponential shape ending with a thin array of eight cantilevers with a size of (500 x 140 x 10) µm³. Based on the behavior of the natural frequency, it is possible to estimate the variation of the density of a fluid or the presence of markers in a gas or liquid. To select the target analyte, it is necessary to identify the binding site as well as the covalent or noncovalent interactions between the functional monomer and the analyte. It can monitor natural, industrial, and residential areas by analyzing the eigenfrequency change when the micro-beam is immersed in a sample of these mediums. The numerical analysis using COMSOL Multiphysics software conducted was based on theoretical computations. The frequency resolution of the self-sensing micro-cantilever achieved in the fluid is 50 Hz/mmol.L-1 with mode 7th around 1.14 MHz However, we have noticed that this device can detect changes in density up to 0.054 %.

S. Weheabby, A. Al-Hamry, A. E. Deller, J. G. A. Ruthes, R. J. Silva, O. Kanoun
Ionic liquid functionalized graphene oxide decorated by gold nanoparticles for electrochemical detection of pirimicarb pesticides

Monitoring pesticide contaminants in diverse environmental systems has become a significant concern. A non-enzymatic electrochemical sensor for pirimicarb pesticide detection has been produced by functionalization of the screen-printed carbon electrodes (SPCE) with graphene oxide, ionic liquid, and gold nanoparticles (GO/IL/AuNps/SPCE). Cyclic voltammetry and electrochemical impedance spectroscopy techniques were applied for the electrochemical characterization of the modified electrode in the presence of [Fe(CN)6]3-/4- as a redox probe. The system showed an exponential response in a concentration range from 50 pM to 500 nM of pirimicarb with a sensitivity of 5.74 × 10 -3 µA pM-1 mm-2 , and the Limit of detection (LOD) is 10.30 pM.

R. A. Bouchhima, M. Ksibi
Mapping halophytes using decision tree approach

Ghannouch in the south-east of Tunisia is colonized by halophytes. Mapping and monitoring with remote sensing approach are previsioned as the ways to trace the spatial and temporal confines of their distribution in order to reveal the extent of salinization and its dynamic. The distinguishing of halophyte vegetation can be done by examining optical remote detecting information as a tree approach applied to European Space Agency Sentinel-2 symbolism. As a result, for an area of interest of 50 × 50 km², at least 68 % was classified as halophyte land cover. This mapping exercise represents an important step toward improved halophyte mapping in Tunisia and could be used to monitor the status of other salinity-prone regions in the world.

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.

Page 41 of 955 Results 401 - 410 of 9546