In this present work, we have studied the effect of organic solvents and acetylacetone (Acac) molar ratio on several properties of TiO
2
thin films prepared by pneumatic spray pyrolysis (SP). The TiO
...2
thin films were characterized by the following techniques including the following: X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM) and UV–visible spectrophotometer. The XRD results showed pure anatase TiO
2
thin films with preferential orientation (101) plan, the crystallite size varying between 14.72 and 35.12 nm. The Raman spectroscopy confirmed the formation of the only phase of TiO
2
(anatase). The morphological properties were investigated by SEM. The UV–Visible spectrophotometer showed the semiconducting properties of anatase TiO
2
, and the optical band gap was ranged between 3.17–3.34 eV. The refraction index, the extinction coefficient and the porosity were estimated using transmittance values. The TiO
2
thin films have had good properties. They were prepared by low-cost technique, spray pyrolysis, by saving energy and time because the samples were synthesized using air pulverization without using any oxygen sources and without any annealing requires the following: CVD room, low pressure and more time for annealing (Sahoo et al. 2019 in Phys Chem Chem Phys 21: 6198–6206).
In mammalian cells, two cellular organelles, mitochondria and peroxisomes, share the ability to degrade fatty acid chains. Although each organelle harbors its own fatty acid β-oxidation pathway, a ...distinct mitochondrial system feeds the oxidative phosphorylation pathway for ATP synthesis. At the same time, the peroxisomal β-oxidation pathway participates in cellular thermogenesis. A scientific milestone in 1965 helped discover the hepatomegaly effect in rat liver by clofibrate, subsequently identified as a peroxisome proliferator in rodents and an activator of the peroxisomal fatty acid β-oxidation pathway. These peroxisome proliferators were later identified as activating ligands of Peroxisome Proliferator-Activated Receptor α (PPARα), cloned in 1990. The ligand-activated heterodimer PPARα/RXRα recognizes a DNA sequence, called PPRE (Peroxisome Proliferator Response Element), corresponding to two half-consensus hexanucleotide motifs, AGGTCA, separated by one nucleotide. Accordingly, the assembled complex containing PPRE/PPARα/RXRα/ligands/Coregulators controls the expression of the genes involved in liver peroxisomal fatty acid β-oxidation. This review mobilizes a considerable number of findings that discuss miscellaneous axes, covering the detailed expression pattern of PPARα in species and tissues, the lessons from several PPARα KO mouse models and the modulation of PPARα function by dietary micronutrients.
Semiconductor compounds Cu
2
MnSnS
4
absorbers materials were synthesis by the sol–gel approach and deposited using dip-coating technique on ordinary glass substrates. In this work, we have studied ...the effect of various annealing temperature such as: 400 °C, 425 °C, 450 °C and 475 °C for 1 min on the structural, compositional, morphological, optical and electrical investigations. CMnTS thin films have been characterized by some analyse techniques such as: X-ray diffractometer (XRD), Raman spectroscopy, dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM), UV–visible spectroscopy and four-point probe method. XRD data proved the formation of stannite Cu
2
MnSnS
4
with privileged direction at (112) plane. Crystallite size of stannite CMnTS thin films increased with the increase of annealing temperature from 7.26 to 11.57 nm with annealing temperature augmented. Raman experiments complete the confirmation of stannite CMnTS thin films existence by Raman vibrational modes located at 288 cm
−1
and 330 cm
−1
. EDS analysis demonstrated close-stoichiometry of CMnTS thin films annealed at 450 and 475 °C. SEM images demonstrated the improvement of crystallinity and uniformity of surface morphologies when annealing temperature is 475 °C. UV–visible spectroscopy indicated that the transmittance spectra increased when annealing temperature increased in the wavelength range of 450–850 nm. The absorption coefficient values are higher than 10
4
cm
−1
, the approximated bandgap of CMnTS absorber material decrease in the range of 1.72–1.5 eV when annealing temperature increased. The electrical resistivity of CMnTS thin films decrease from 4.77 to 0.85 (Ω.cm). These properties are appropriate for photovoltaic solar cells applications.
In this study, we reported the impact of spray time and substrate temperature on several properties of TiO
2
thin layers elaborated by facile and robust spray pyrolysis (SP) technique. The TiO
2
thin ...layers were characterized by the following techniques: X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM) and UV–visible spectrophotometer (UV–Vis). The XRD results demonstrated the pure anatase phase of TiO
2
thin layers with the preferential direction along < 101 > direction. The vibration characteristics of TiO
2
have been confirmed by Raman vibratory modes located at 143, 396, 518 and 637 cm
−1
which certified the formation of a single phase of TiO
2
Anatase. The SEM images showed the formation of granular TiO
2
layers. The UV–Vis spectrophotometer displayed the semiconducting properties of TiO
2
semiconductor, the band gap energy was ranged between 3.10 and 3.30 eV. All parameters investigated in this study confirmed that TiO
2
deposited by the inexpensive spray pyrolysis during 25 min at 500 °C had the required properties for gas sensing applications and are in good agreement with those reported in the literature. The sensing properties of the elaborated TiO
2
thin films to NO
2
showed their high suitability to detect this pollutant gas.
Quaternary semiconductor Cu
2
NiSnS
4
thin film was made by the sol–gel method associated with dip-coating technique on ordinary glass substrates. In this paper, we have studied the impact of ...dip-coating cycle at different cycles: 4, 5 and 6 on the structural, compositional, morphological, optical and electrical characteristics. CNTS thin films have been analyzed by various characterization techniques including X-ray diffractometer (XRD), Raman measurements, scanning electron microscope (SEM), energy-dispersive X-ray spectroscope (EDS), UV–Visible spectroscopy and four-point probe method. XRD spectra demonstrated the formation of cubic Cu
2
NiSnS
4
with privileged orientation at (111) plane. Crystallite size of cubic CNTS thin films increases from 6 to 9 with augmentation of dip-coating cycle. Raman scattering confirmed the existence of CNTS thin films by Raman vibrational mode positioned at 332 cm
−1
. EDS investigations showed near-stoichiometry of CNTS sample deposited at five cycles. Scanning electron microscope showed uniform surface morphologies without any crack. UV–Vis spectroscopy indicated that the optical absorption coefficient values are larger than 10
4
cm
−1
. Estimated band gap energy of CNTS absorber layers decreases from 1.64 to 1.5 eV as dip-coating cycle increased. The electrical conductivity of CNTS thin films increases from 0.19 to 4.16
Ω
cm
-
1
. These characteristics are suitable for solar cells applications.
At an urban site in Kenitra, Morocco, two aerosol size fractions (PM2.5 and PM10) were sampled for four seasons to characterize the seasonal trends of particulate (PM) and carbonaceous (BC) aerosols. ...An in-depth statistical analysis of the lag-effects of meteorology on collected data was investigated using uni- and multivariate linear regression analyses. The results revealed significant seasonal trends for PM10, PM2.5, and BC. PM concentrations showed the maximum values in autumn (61.4 ± 24.5 µg/m3 for PM10 and 21.2 ± 8.2 µg/m3 for PM2.5), while the minimum was observed in winter (40.2 ± 17.1 µg/m3) for PM10 and in summer (14.3 ± 3.3 µg/m3) for PM2.5. High BC concentrations were recorded in summer (6.3 ± 4.2 μg/m3, on average). The relative humidity 1–2 days earlier showed a higher negative correlation with the PM concentrations (except in winter), and the temperature 1–3 days earlier showed a negative correlation with the PM2.5 in winter and summer and a positive one with the PM10 in autumn. Wind speed was negatively associated with PM10 on the current day in winter and 3 days earlier in summer. However, diverse effects of wind speed on PM2.5 were observed (negative in summer and positive in spring). These results confirm the important role of meteorology in the formation of urban air pollution with pronounced variations in different seasons.
Insufficient data on the chemical composition of PM2.5 and its emission sources in the southwestern (SW) Mediterranean area has been identified. Ambient PM2.5 samples were collected in an urban area ...of Tetouan city, northern Morocco. Chemical mass closure calculations and positive matrix factorization were performed for the comprehensive dataset of PM2.5 chemical analyses. Mass closure improved when multipliers (1.2 and 0.23, respectively) were used for the conversion of organic carbon (OC) and calcium ion (Ca2+) into particulate organic matter (POM) and mineral dust masses, respectively. The mass closure model performed well in this SW Mediterranean region, with a significant correlation (r2 = 0.97) obtained between gravimetrically measured and chemically determined PM2.5 mass. The one-year average concentration of PM2.5 was 17.96 μg/m3, and the major chemical components were POM (34%), secondary inorganic aerosol (SIA) (28%), and black carbon (18%), while unidentified mass was 4%. The mass concentration and most of the chemical components of PM2.5 showed clear seasonal variations, with a summer-high and winter-low pattern for SIA, dust, and BC. In the winter months, POM was the dominant component. Source apportionment analysis revealed that PM2.5 emission sources, regarding their typical tracers, were ammonium sulfate (SO42−, NH4+, K+, NO3−), road traffic and biomass burning emissions (OC, BC), fresh sea salt (Cl−, K+, NO3−), aged sea salt (Mg2+, Na+, Ca2+), and oxalate-rich (oxalate, NO3−) factors. Further, it is hoped that these findings help to improve the scientific understanding of SW Mediterranean aerosols.
Al Hoceima Bay, located on Morocco's Mediterranean coast, is a very important ecosystem characterized mainly by seaside tourism and sea fishing. Continental inputs and climate change generally ...contribute to modifying the environmental parameters that characterize coastal waters. This work aims to characterize the seasonal and spatial variation of the physico-chemical parameters of the surface waters of Al-Hoceima Bay during an annual cycle in the context of global change. Four sampling campaigns (autumn, winter, spring, summer) were conducted during the period 2022-2023 in a sampling network of 15 stations covering all areas of the bay. Surface water samples were collected and analyzed by a multi-parameter instrument. The results show a significant seasonal variation (p < 0.01) for parameters analyzed. Temperatures ranged from 15.59°C to 21.8°C, pH ranged from 7.8 to 8.4. Dissolved oxygen ranged from 3.7 mg/l to 7 mg/l. Salinity ranged from 35.7 g/l to 39.5 g/l. Conductivity ranged from 54 ms/cm to 56.5 ms/cm.
Marchica Lagoon, a Ramsar site on the Mediterranean coast of Morocco, is experiencing the impacts of watershed pollution, which includes pollutants from the domestic, agricultural, industrial, and ...mining sectors. Restoration actions were undertaken around this lagoon during the last decade in order to protect its ecological value and to develop tourist activity. To conserve the biodiversity in the lagoon, it is important to assess the environmental state of this ecosystem. This study aims to evaluate the ecotoxicological state of sediments through the post restoration characterization of the trace elements Pb, Cu, Zn, Cr, Co, and Ba, as well as their correlation to the major elements, grain size, and total organic carbon, sampled during two campaigns (the wet and dry seasons of 2018) across a sampling network of thirteen stations. Multivariate analysis and ecotoxicological risk assessment of the trace elements using the sediment quality guidelines and five pollution indices (geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (CF), pollution-load index (PLI), and mean effect range median quotient (m-ERM-Q)) revealed contamination of the lagoon by Pb, Zn, and Cu, and minimal pollution by Cr, Co, and Ba. The distribution of the biological-risk index reveals that four zones of the lagoon may present a high probability of toxicity, thus constituting potential risk areas for aquatic organisms: during the wet season, the area in the northwestern sandbar border, the southwest eutrophication zone, and the mouth of the stream valley conveying industrial discharges; and during dry season, the northwestern eutrophication zone. Despite the restoration actions achieved around the lagoon, the lead, zinc, and copper concentrations increased, and their variation was significant between group stations. The biodiversity conservation of Marchica Lagoon requires continuous monitoring and assessment, as well as the implementation of an integrated management plan with restoration actions, not only around the lagoon, but also at its watershed level.
Covid-19 was first reported in Morocco on March 2, 2020. Since then, to prevent its propagation, the Moroccan government declared a state of health emergency. A set of rapid and strict ...countermeasures have taken, including locking down cities, limiting population's mobility and prohibiting almost all avoidable activities. In the present study, we attempted to evaluate the changes in levels of some air pollutants (mainly PM10, NO2 and SO2) in Salé city (North-Western Morocco) during the lockdown measures. In this context, a continuous measurement of PM10, SO2 and NO2 was carried before and during the Covid-19 lockdown period. As a consequence of the security measures and control actions undertaken, the emissions from vehicle exhaust and industrial production were significantly reduced, which contribute to the decrease in the concentrations of the studied pollutants. The obtained results showed that the difference between the concentrations recorded before and during the lockdown period were respectively 75%, 49% and 96% for PM10, SO2 and NO2. PM10 levels were much less reduced than NO2. The three-dimensional air mass backward trajectories, using the HYSPLIT model, demonstrated the benefits of PM10 local emission reductions related to the lockdown were overwhelmed by the contribution of long-range transported aerosols outside areas. In addition, noteworthy differences in the air mass back trajectories and the meteorology between these two periods were evidenced.
Daily average concentrations of SO2 and NO2 from March 11th to April 2nd in Salé city. Display omitted
•PM10, NO2 and SO2 concentrations were reduced by more than half during the covid-19 lockdown period.•Covid-19 countermeasures contribute to reduce all pollutant concentrations but with significant differences among them.•Long-range transported aerosols contributions overcame the PM10 local emission reductions benefits related to the lockdown.
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