Publications

Abstract The processed discharges from Tangier Automotive City's (TAC) Chrafate Wastewater Treatment Plant (WWTP) contaminate the Jouamaa Hakama groundwater and the Ouljat Echatt river. We aimed to study the unknown interactions between surface water (SW) and groundwater (GW). A total of nine Jouamaa Hakama GW samples and eleven Ouljat Echatt SW samples were taken and analyzed in 2021 and 2022 to determine 16 physical and chemical parameters (pH, temperature (T), electrical conductivity (EC), dissolved oxygen (DO), total hardness (TH), turbidity (TURB), and total dissolved solids (TDS), cations: Na+, K+, Mg2+ and Ca2+, anions: Cl-, CO32-, HCO3-, NO3-, and SO42-). For exploitation of the data, we used a methodology based on hydrochemical modeling (HM), principal component analysis (PCA), Water Quality Index (WQI), Irrigation Water Quality Index (IWQI), inverse distance weighted interpolation (IDW) using Geographic Information Systems (GIS), and regression analysis (RA). We studied the interaction of the surface water of the river (contaminated by discharges from the WWTP) with the shallow groundwater on a strip of 100 m on either side of the river to understand the transverse and longitudinal dispersion of this pollution The investigations indicated that the major ions found in GW and SW were characterized in a different order in the anion list order Cl- > CO32- > NO3- > HCO3- > SO42- and Cl- > SO42- > CO32- > NO3- > HCO3-, respectively, while the concentrations of cations showed the same order for both: Na+ > Ca2+ > Mg2+ > K+. As a result, GW showed in the Piper diagram the type of sodium chloride to magnesium carbonate, while SW belongs to the sodium chloride to magnesium sulfate type. The WQI showed that the river waters are all unsuitable for use (WQI > 100), while the GW is of poor quality (WQI > 76). Moreover, the results of the GW-SW interaction along the river revealed a significant relationship (R-2 = 0.85), which means that strong circulation and the infiltration of contaminated SW into shallow GW occur in this area. The approaches followed have been proven effective in evaluating water quality for human and animal uses. These results can help decision-makers in the region take suitable management measures to mitigate this environmental problem.

Abstract Biochemical-chemical sensing with plasmonic sensors is widely performed by tracking the responses of surface plasmonic resonance peaks to changes in the medium. Interestingly, consistent sensitivity and resolution improvements have been demonstrated for gold nanoparticles by analyzing other spectral features, such as spectral inflection points or peak curvatures. Nevertheless, such studies were only conducted on planar platforms and were restricted to gold nanoparticles. In this work, such methodologies are explored and expanded to plasmonic optical fibers. Thus, we study-experimentally and theoretically-the optical responses of optical fiber-doped gold or silver nanospheres and optical fibers coated with continuous gold or silver thin films. Both experimental and numerical results are analyzed with differentiation methods, using total variation regularization to effectively minimize noise amplification propagation. Consistent resolution improvements of up to 2.2x for both types of plasmonic fibers are found, demonstrating that deploying such analysis with any plasmonic optical fiber sensors can lead to sensing resolution improvements.

Abstract Hydrogen peroxide is usually added to products to delay the development of microorganisms mainly in milk, hence increasing its stability over time, however the side effects can become devastating to human health.A technique is presented consisting of detecting hydrogen peroxide as an adulterant in milk through a sensor where pretreatment of the sample is not necessary, using a single use membrane. The detection of hydrogen peroxide in fresh-raw, whole, semi-skimmed and skimmed milk was performed using a luminol chem-iluminescence reaction.For hydrogen peroxide water solutions, a linear response was attained from 1.0 x 10-4 to 9.0 x 10-3 %w/w and an LOD (limit of detection) of 3.0 x 10-5 %w/w was determined. An R-squared value of 0.97 and a relative standard deviation lower than 10%, were achieved.Hydrogen peroxide concentration as low as 1.0 x 10-3 %w/w was measured for fresh-raw, skim and whole milk and for semi-skimmed milk, as low as 2.0 x 10-3 %w/w.The methodology presented, as long as our knowledge, is original, rapid, ecological and inexpensive. In regard of the sensitivity obtained, the methodology has great possibility to be applied in the detection of hydrogen peroxide in several areas. It is envisaged monitoring of food quality, agriculture systems and environment pollution.

Abstract Tanacetum annuum L. is a Mediterranean plant, commonly known as Blue Tansy due to its blue colour as an essential oil, which is widely used for medicinal purposes. However, there are no studies on the bioactive compounds (especially, phenolic compounds) and the biological properties of their organic extracts. Herein, the purpose of the present work was to investigate the chemical composition of the essential oil and crude extracts of the T. annuum aerial parts collected from northern Morocco and to evaluate their antioxidant and antifungal activity against Fusarium oxysporum f. sp. albedinis, an agent causing Bayoud disease of the date palm, an important food source and commercial perennial crop in the Sahara and North Africa. Chemically, Folin-Ciocalteu and aluminium chloride colourimetric methods were used to determine the total phenolic (TPC) and total flavonoid (TFC) contents, respectively; polyphenols were characterized using HPLC-MS, while GC-MS was used to analyse the essential oil composition. Moreover, the evaluation of antioxidant and antifungal activities was carried out using the DPPH test and microdilution method, respectively. The results showed that the three T. annuum parts (stems, leaves and flowers) extracts contained important TPC and TFC with values varied between 51.32 and 116.32 mg/g of dry crude extract (DCE). HPLC-MS analysis revealed the identification and quantification of 19 phenolic acids and flavonoids with an emphasis on apigenin 7-glucoside (4540 mu g/g of dry weight (DW)), luteolin 7-glucoside (2804 mu g/g DW) and salicylic acid (1878 mu g/g DW). Additionally, 39 biomolecules were identified in the essential oil using GC-MS, which were predominated by camphor (16.69%), a-pinene (12.37%), bornyl acetate (11.97%) and limonene (11.10%). The methanolic and hydro-methanolic extracts of T. annuum parts demonstrated a strong antioxidant property with IC50 values ranging between 0.22 and 0.65 mg/mL. Concerning antifungal activity, the essential oil and crude extracts of the Moroccan Blue Tansy exhibited a potent capacity against F. oxysporum f. sp. albedinis at low concentrations, with MIC and MFC values of 3.33 and 4.58 mu L/mL for the essential oil and values of 3.33 and 9.17 mg/mL for crude extracts, respectively. Overall, these results demonstrated T. annuum as an important source of bioactive compounds and contribute significantly to the potential of using essential oils and extracts for controlling the Bayoud disease of date palms. Moreover, the finding suggests that T. annuum can be highly useful for phytosanitary and pharmaceutical industries.

Abstract In this work, undoped TiO2 and Fe-doped TiO2 materials as photocatalysts for water remediation, were synthesized using wet chemical methods (sol-gel + precipitation). Their crystalline structure, optical and morphological properties were explored using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) and Raman spectroscopies, UV-vis diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy coupled to the energy dispersive X-Ray spectroscopy (SEM-EDS). The photocatalytic performance of the synthesized materials was assessed through the degradation of methyl orange (MO) under UV-A and visible-light irradiations. The structural study showed the existence of predominate anatase phase in all synthesized nanomaterials. The optical study showed a widening of the band gap for Fe-doped TiO2 materials and revealed a decrease in charge carrier's recombination for all Fe-doped TiO2 nanomaterials compared to undoped TiO2. The morphological study confirmed the nanometric scale of the materials particles. The photocatalytic experiments revealed an enhanced photocatalytic activity of 0.5 %wt Fe-doped TiO2, only under UV-A light, compared to the rest of the prepared nanomaterials. The enhanced photocatalytic activity has been attributed to the efficient charge separation of electrons and holes.(c) 2023 Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Abstract Using surface resonance (SPR) as a sensitivity enhancer, this work describes the development of a transmissive multimode optical fiber sensor with a gold (Au) thin film that measures glucose concentration. The fiber's cladding was initially removed, and an Au layer was then sputtered onto its surface to simultaneously excite SPR and reflect light, making the SPR sensor extremely sensitive to changes in the environment's refractive index. A range of glucose concentrations, from 0.0001 to 0.5000 g/ml, were tested on the sensor. A maximum sensitivity of 161.302 nm/(g/mL) was attained for the lowest glucose concentration, while the highest concentration yielded a sensitivity of 312.000 nm/(g/mL). The proposed sensor's compact size, high sensitivity, good stability and practicality make it a promising candidate for a range of applications, including detecting diabetes.

Abstract Reinforced concrete structures are prevalent in infrastructure and are of significant economic and social importance to humanity. However, they are prone to decay from cement paste carbonation. pH sensors have been developed to monitor cement paste carbonation, but their adoption by the industry remains limited. This work introduces two new methods for monitoring cement paste carbonation in real time that have been validated through the accelerated carbonation of cement paste samples. Both configurations depart from traditional pH monitoring. In the first configuration, the carbonation depth of a cement paste sample is measured using two CO2 optical fiber sensors. One sensor is positioned on the surface of the sample, while the other is embedded in the middle. As the carbonation depth progresses and reaches the embedded CO2 sensor, the combined response of the sensors changes. In the second configuration, a multimode fiber is embedded within the paste, and its carbonation is monitored by observing the increase in reflected light intensity (1.6-18%) resulting from the formation of CaCO3. Its applicability in naturally occurring carbonation is tested at concentrations of 3.2% CO2, and the influence of water is positively evaluated; thus, this setup is suitable for real-world testing and applications.

Abstract Measuring gas and liquid flow rate is paramount in various scientific and industrial applications. This work presents an optical fiber flowmeter based on a graphene oxide (GO) coated Michelson interferometer. The interferometer is fabricated using a long-period fiber grating (LPFG) followed by a GO-coated single-mode fiber (SMF). By radiating the GO coating, it experiences photothermic effect that induces local heating of the film. This results in a variation in the effective refractive index in the cladding modes, which induces a phase shift on the interferometer spectrum. When a gas flow is introduced near the coated fiber, the hot-wire region will experience a reduction in temperature proportional to the flow rate. The flowmeter exhibited a linear wavelength shift to the flow rate with an absolute sensitivity of 17.4 +/- 0.8 pm/(L.min-1) for gas flow rates between 2 and 8 L/ min. Furthermore, the dynamic response of the sensor was studied, attaining a maximum response time of 1.1 +/- 0.4 s

Abstract The composite film of mesoporous silica coated NaYF4:Er3+/Yb3+ upconversion nanoparticles and gold nanoparticles (AuNPs) in Poly vinyl alcohol (PVA) medium were prepared. The effect of the concentrations of AuNPs with 0 mu l, 50 mu l, 100 mu l and 150 mu l on the structure and upconversion luminescence intensity were studied. The phenomenon of enhancement in upconversion luminescence intensity due to AuNPs were explained via surface plasmon resonance (SPR) phenomenon. Apart from this the XRD, FE-SEM and AFM studies were done for estimation of structure and surface morphology etc. The impurities were estimated through FTIR analysis. The optical properties of these polymer composite films were studied via UV-vis absorption spectra and upconversion luminescence spectra analysis. A low temperature sensing ability of these films have been demonstrated for the suitability of these films in bio-medical applications.

Abstract The increasing demand for precise chemical and biological sensing has led to the development of highly efficient plasmonic optical fiber sensors. Therefore, it is essential to optimize and match the operating wavelength region of both the optical fiber configuration and localized surface plasmon resonance of nanoparticles (NPs). This can be achieved by developing NPs that can reach resonance at near-infrared wavelengths, where refractive index sensitivity is enhanced, and silica optical fibers have lower losses. High aspect-ratio bimetallic Au@Ag nanorods and different side-polished fiber structures are tested using numerical simulations. The selected optical fiber configuration was based on a side-polished fiber with a 1 mm polished section. It is compared power losses and power at the NP interface for two configurations: a step-index single-mode fiber (SMF) with core/cladding diameters of 8.2/125 µm and a multimode graded-index fiber (GIF) with 62.5/125 µm at various polishing depths. The results showed that the best performance for both configurations was achieved at similar polishing depths, namely 59.5 and 55.2 µm for the SMF and GIF, respectively. The optical impact of retardation effects due to the proximity with the fiber structure were also observed, which caused a reduction in sensitivity from 1750 nm/RIU to 1500 nm/RIU and a red-shift of around 70 nm. © 2023 SPIE.