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The presence of persistent organic pollutants (POPs) in human milk is an indicator of the level of these substances in the environment and enables evaluation of the potential exposure of breastfed children. POPs concentrations in a Moroccan human milk pooled sample (59 donors) were determined for the first time by the WHO reference laboratory to provide a baseline and allow monitoring of the future trends for those persistent organohalogen compounds. Eighty-one different POPs, including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and dioxins and furans (PCDD/Fs) were identified and quantified by using gas chromatography (GC) with an electron capture detector (ECD) and confirmed by gas chromatography-mass spectrometry (GC/LRMS). The obtained results showed that the sum of DDT (sum of o,p'-DDD, p,p'-DDD, o,p'-DDE, p,p'-DDE, o,p'-DDT, and p,p'-DDT) was 237.9 ng/g, representing 94.0% of all detected OCPs levels, with a dominance of p,p'-DDE, and p,p'-DDT. Cis-heptachlor epoxide, HCB, and HCH were found at much lower levels. PCB indicator level was 60.7 ng/g of lipid, with the dominance of PCB 138, PCB 153, and PCB 180, presenting 98.3% of the total. Among the 25 PBDE congeners quantified, BDE-47, BDE-153, BDE-197, and BDE-207 were the dominant congeners account for 15.4% of the total concentration of PBDE (1.3 pg/g lipid). The lipid-adjusted level of PCDD/Fs and dl-PCBs expressed in Toxic Equivalents (TEQs: 6.65 pg/g) were lower in comparison to those found in the other countries. In summary, detected POPs levels in Moroccan human milk were much lower compared to the other countries, reflecting the effectiveness of the compliance with Stockholm Convention requirements on eliminating or reducing emissions of selected POPs. Continued monitoring is needed for these compounds, for which this is the first data available, provided by the WHO/UNEP survey in Morocco.

The anti-corrosion features of 1-dodecyl-3-phenylquinoxalin-2(1H)-one (QO12) for carbon steel CS were evaluated in a 1 M HCl solution using potentiodynamic polarization (PDP), electrochemical impedance (EIS) and UV-visible spectroscopy, and scanning electron microscopy (SEM), as well as quantum-chemical methods. The inhibition performance achieves a maximum of 95.33% at 0.001 M. The PDP study revealed that QO12 acts with the character of a mixed-type inhibitor. The EISs mention that the process of corrosion for CS is essentially predominated by the transfer-of-charge mechanism. Moreover, quinoxalinone adsorption follows the Langmuir adsorption isotherm. SEM snapshots show no deterioration after the contribution of QO12 compared to the reference electrolyte. Theoretical calculations suggest that the envisaged inhibitor presents a perfect arrangement capacity through the structure of quinoxalinone.

Durable chitosan-based coating material used as a barrier for slow-release fertilizers in the agricultural soil. This approach decreases the intense usage of fertilizer and works on their accessibility for the plants' necessities. In present paper, the proposed coating material was prepared on the basis of chitosan-kaolinite composite (CS-Gl-K). Fourier transform infrared spectroscopy analysis (FTIR), Scanning Electron Microscopy (SEM), thermogravimetric analysis (ATG), XRD, swelling degree and biodegradability studies were used to analyze the influence of the kaolinite clay incorporation in chitosan film properties. The characterization of the chitosan composites has been thoroughly studied. The NPK mineral fertilizer was coated according to the dip-immersing process of chitosan-kaolinite composites. Slow-release efficiency was evaluated by determining the rate of phosphorus release from the covered granules into water and soil. Moreover, phosphorus release from coated NPK/CS-Gl-K granules was generally delayed contrasted with NPK/uncoated. In addition, the biodegradation investigation of the composite material (CS-Gl-K) in soil was affirmed its durability. The proposed coating material has good slow-release properties, low cost and is environmentally friendly. The FTIR, ATG and XRD spectra revealed a good intercalation between the kaolinite-clay pores and chitosan chains.

The current study aimed to examine the quality of breast milk in Kenitra city (Morocco), regarding its levels of essential elements Iron (Fe), Copper (Cu), and Zinc (Zn) and heavy metals chromium (...

International audience; The heterocyclic system, namely 4-phenyl-decahydro-1H-1,5-benzodiazepin-2-one (POBZ) was inspected as a corrosion inhibitor of carbon steel (CS) in a 1 M HCl medium through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization measurements (PDP), and scanning electron microscopy (SEM). The experimental data indicate that the inhibiting action augments with augmenting POBZ amount and reduces with augmenting temperature. The inhibiting action efficiency of 90.98% is obtained with 0.001 M at 303 K. The potentiodynamic polarization (PDP) results mentioned that the POBZ is of mixed type. The adsorption of POBZ on the CS followed Langmuir isotherm. SEM exams affirmed that the steel surface is smooth in presence of POBZ. In light of the calculations of density functional theory (DFT) and molecular dynamics simulation, the mechanism of POBZ inhibitory activity was addressed.

4-(prop-2-ynyl)-2H [1,4]-benzothiazin-3(4H)-one (PBO) was synthesized and evaluated on corrosion resistance for mild steel (MS) in1 M HCl environment. The molecular and crystal structure of PBO has been determined by single-crystal X-ray crystallography, Hirshfeld surface (HS) analysis was carried out by using Crystal Explorer 17.5. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques were used to find corrosion rate (CR) and corrosion inhibition efficiency (η) in the presence and absence of PBO. These techniques were supported with energy dispersive X-ray (EDX) and scanning electron microscope (SEM). Molecular Dynamics Simulation (MDS) and Frontier Molecular Orbital (FMO) are realized by means of the Density Functional Theory (DFT) method. The results show that PBO could offer an inhibition efficiency of 92% at 303 K. The type of inhibition mechanism of PBO was mixed-type. The Langmuir isotherm proved the highest compliance with experimental data, representing the generation of protective mono-layer of inhibitors on the MS substrate. The SEM pictures displayed a metallic substrate covered with a highly compact protective layer covered. The theoretical findings suggested by electronic/atomic computer simulations supported the inhibitive chemicals interfacial adsorption through reactive centres.

The present study focuses on the inhibitive action of 1H, 4H, 5H-pyrazolo[3,4-d]pyrimidine (PPO) as corrosion inhibitor for copper in 3% NaCl solution by electrochemical techniques and gravimetric method. Results indicated that the compound under study exhibited good inhibition activity with a maximum value of 96.5% at 10−3M. The compound was classified as a mixed type inhibitor with an anodic predominance. The protection efficiency was enhanced with increasing the inhibitor concentration and decreased with the increment of temperature. The adsorption of the inhibitor occurred spontaneously and obeyed to Langmuir isotherm. Monte Carlo simulations showed that PPO had a high adsorption energy and possessed the ability to replace pre-adsorbed aggressive species on copper surface and then formed a protective film. PPO was adsorbed in a parallel configuration providing better coverage of the metal surface.

This work presents the synthesis of a new quaternary compound Cu2CoGeS4 (CCGS) thin film for the first time combined with first-principles calculations (DFT, WIEN2k). The synthesis was done via spray ultrasonic of Cu–Co−Ge precursors onto glass substrate followed by high−temperature (500 °C) sulfurization under inert atmosphere (Ar). A near 2:1:1:4 stoichiometry of Cu2CoGeS4 was confirmed from EDX analysis. X−Ray−Diffraction(XRD) analysis confirmed the formation of polycrystalline Cu2CoGeS4 (CCGS) thin film with a tetragonal stannite structure( 1 4 ‾ 2 m ). Raman spectroscopy confirmed the purity of the film and showed the presence of the characteristic predominant peak ( 339 cm − 1 ) of the tetragonal stannite structure. The band structure displayed a direct band−gap. The experimental and theoretical optical band gaps were found to be about 1.75 eV with high absorption-coefficient in the visible region of the solar spectrum. Electrical measurement confirmed the p-type conductivity with a resistivity of 0.89( Ω . cm − 1 ) and a carrier concentration of 4.6 1016 cm−3. These results and the photoresponse measurement make the Cu2CoGeS4 (CCGS) a potential material for solar cell application and will draw the attention to develop this material in several other applications.

This work is devoted to the study of the inhibition of corrosion of mild steel (MS) in molar hydrochloric acid (1 mol⋅L-1 HCl) by two named quinoxaline derivatives namely, 2-(2,4-dichlorophenyl)-1,4-dihydroquinoxaline (HQ) and 2-(2,4-dichlorophenyl)-6-methyl-1,4-dihydroquinoxaline (CQ). The inhibitory efficacy of HQ and CQ compounds is first evaluated using the gravimetric method and using electrochemical techniques (stationary and transient techniques). The results showed that our compounds are efficient corrosion inhibitors and the inhibition rates (ηEIS%) reached up to 91% and 94.2% at 10−3 mol⋅L-1 for HQ and CQ, respectively. The mentioned molecules are classified as mixed-type inhibitors. The adsorption of these inhibitors on the surface of steel in hydrochloric HCl 1 mol⋅L-1 medium obeys the Langmuir adsorption isotherm. The results of the scanning electron microscope (SEM) showed the formation of a protective film on the surface of the steel in the presence of the inhibitors studied. Elementary analysis is obtained by energy dispersive X-ray spectroscopy (EDS). The inhibition property was further elucidated by theoretical approaches such as: Density Functional Theory (DFT), quantum chemical descriptors (QCD), local reactive indices, solvent effect, theoretical complexation, Molecular Dynamic (MD) simulation, effect of temperature on adsorption energy (Eads), Radial Distribution Function (RDF), and Mean Square Displacement (MSD). The results of these approaches support the experimental results.

Phosphate glasses of the ternary system Bi2O3-Nb2O5-P2O5 were studied in two compositional series, namely xBi2O3-5Nb2O5-(95−x)P2O5 (serie B), with x = 10–17,5 mol% Bi2O3, and 10Bi2O3−xNb2O5-(90−x)P2O5 (serie N), with x = 2,5–15 mol% Nb2O5. Seven homogeneous glassy samples were prepared, and their amorphous structure were confirmed by X-ray diffraction. The dielectric properties such as dielectric constant ( e ′ ) and dielectric loss (tanδ) were determined as a function of temperature ranging from 100 °C to 500 °C at a fixed applied frequency of 16 kHz. Replacing P2O5 by Bi2O3 or Nb2O5 decreases the dielectric parameters in both series. These results are attributed to the increase in the cross-link density and the rigidity of the glass, leading therefore to a decrease of the polarization. The usual increasing behavior of ( e ′ ) and (tanδ) with temperature may be explained by the augmentation of the orientation polarization and the electrical conduction losses values.

In this work we studied the complexation of Zn2+ in dilute and concentrated phosphoric media. The investigation method used is the liquid-liquid extraction. This method allowed us to define the nature of the zinc phosphoric species and to calculate their stability constants. These are the following entities ZnH2PO4+ and ZnHPO4, whose stability constants are respectively equal to 5.83·10−2 and 5.83·10−5. We also studied at pH and analytical concentration of H3PO4 data the effect of concentration on this complexation. In addition, the sharing data show that the chelate extracted in the organic phase is Z n X 2 , ( H X ) 2 - formed according to the reaction: Z n 2 + + 2 ( H X - ) 2 ⇆ Z n X 2 , ( H X ) 2 - + 2 H + of constant Ke = 5.12·10−3, (X = di (2-ethylhexyl) phosphoric).

The ion exchange method chosen in this work is analogous to that of the slopes used in liquid-solid extraction. The exploitation of this method studies the sharing of Cr(VI) between the liquid and solid phase and makes it possible to highlight the predominant surface complexes, four types of complexes are identified. These complexes result from two intrinsic complexing reactions (without H3O+ exchange) and two other reactions by 1H+ and 1OH− exchange. In addition, we examined the order of these complexes which defines the number of iron nuclei bound to chromium. The results found in this case indicate that the complexes are monodentated both in acid medium and in basic medium, the stability constant of these complexes are: logK10 = 1,7; logK11 = −3,3; logK1-1 = 8,34.

In this study, 1,5-diallyl-1H-pyrazolo [3,4-d] pyrimidin-4 (5H)-one (PPD) was evaluated as an anticorrosion agent for mild steel (MS) in 1 M HCl. The analysis was performed by weight loss (WL), potentiodynamic polarization measurement, and electrochemical impedance spectroscopy (EIS). The Tafel polarization showed that PPD is a mixed-type inhibitor and reaches 94% of the protective efficiency at 10−3 M. EIS results indicated that the resistance to charge transfer increases with increasing inhibitor concentration and the corrosion of MS is controlled by a charge transfer process. The inhibitor adsorption on the MS surface obeyed the Langmuir’s adsorption isotherm. Thermodynamic parameters were calculated to elaborate the corrosion inhibition mechanism. The micrographic analysis revealed the existence of a barrier layer on the electrode surface with the presence of PPD. Theoretical examinations performed by electronic/atomic computer simulations confirmed that the obtained results were found to be consistent with experimental findings.

The present work aims to examine the link between biodiesel degradation and the corrosion behavior of the 307 L stainless steel used for its storage. Biodiesel was produced from soybean waste cooking oil (SWCO) by trans-esterification process based on a heterogeneous catalyst and methanol. 307 L stainless steel was used to assess the metal surface corrosion after direct contact with the biofuel. The different changes in the biodiesel composition were investigated by FTIR, GS-MS, and UV-absorbance, while the corrosion effect was evaluated by electrochemical methods, SEM/EDS microscopy techniques, X-ray diffraction (XRD) analysis, and UV–Vis–NIR absorbance. The results reveal a weak influence of methyl ester on metal degradation, indicating a low corrosion rate with a localized micro pitting on its surface. Moreover, flame atomic absorption spectroscopy (FAAS) showed the existence of a diminutive number of metal ions, and the electrochemical assays such as electrochemical impedance spectroscopy (EIS) and the polarization curves (PC) exhibited a great corrosion resistance of the 307 L stainless steel by the formation of a passive film.

Quaternary semiconductor Cu2NiSnS4 (CNTS) has emerged as an ideal material for solar cells and has attracted the attention of researchers. Tetragonal-structured CNTS thin films have been successfully synthesized via sulfurization (500°C, argon + sulfur) of co-electrodeposited Cu-Sn-Ni-S precursors on molybdenum (Mo) substrate. The effects of the Ni2+ molarity on the deposition potential, structure, composition, morphology, and optical bandgap of the CNTS thin film were examined by using cyclic voltammetry, Raman spectroscopy, x-ray diffraction analysis, scanning electron microscopy (SEM), energy-dispersive x-ray (EDX) spectrometry, and ultraviolet–visible (UV–Vis) spectrophotometer. X-ray diffraction and Raman analyses confirmed formation of CNTS with tetragonal structure and average crystallite size of 17 nm to 20 nm. SEM revealed that the films were homogeneous, while EDX confirmed the presence of Cu-Ni-Sn-S, and the bandgap of the CNTS thin films was evaluated to lie in the range of 1.6 eV to 1.8 eV, making CNTS a strong candidate material for use in photovoltaic cells.

This study aimed to compare the resistance of dental alloys to corrosion in a solution containing oral bacteria named Streptococcus mutans (S.mutans). The electrochemical behavior of Nickel-Titanium (NiTi) was investigated in sterile Fusayama artificial saliva (AS) with the enrichment medium tryptic soy broth (TSB) in solution 1 and (AS) with (TSB) and bacteria in solution 2. The electrochemical procedures selected for this work were open circuit potentials (OCP), Potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The NiTi surface was examined using optical microscopy.   After 24 hours of immersion in artificial saliva, the results have shown that NiTi revealed high corrosion reactivity in the presence of S. mutans and present pitting corrosion on the surface.

In this investigation, solid phase extraction (SPME) is applied in order to determine the concentrations of insecticides and rat poisons detected in the samples taken on the industrial finished product. Gas chromatography, coupled with mass spectroscopy (GC-MS) is used as an analytical instrument for this purpose. In order to obtain an optimal extraction, different process parameters are examined and optimized. Relevant results are obtained using 30 minutes non-specific binding property time, with 30 minutes stirring mode with magnetic stirring and a temperature of 30 °C. The efficiency of insecticides, poisons for rats, has been demonstrated and pesticides are likely to be at a high concentration in finished industrial products.

Quaternary compound Cu2CoSnS4 (CCTS) is a potential candidate absorber layer in thin film solar cells to produce clean and inexhaustible energy. In this work the Cu2CoSnS4 (CCTS) thin film was synthesized for the first time by co-electrodeposition of Cu–Co–Sn–S precursors on Molybdenum substrate, followed by a high temperature (500 °C) sulfurization under Argon atmosphere. The potential deposition (−0.95 V/SCE) was determined from cyclic voltammetry . The structure, composition and morphology of the CCTS thin film is characterized in detail by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and energy dispersion spectroscopy. The p-type conductivity of CCTS thin film was confirmed using Mott–Schottky analysis and the band gap value was evaluated to be 1.56 eV, which makes CCTS a promising material for solar cell applications.

New Bismuth niobium phosphate glasses having the compositions xBi2O3-(95-x)P2O5-5Nb2O5 with x ranging from 10 to 17.5 mol% were prepared by melting quenching method. The absence of crystalline structure in the prepared phosphate glasses was confined by both X-ray diffraction and Differential Scattering Calorimetry studies. In the other hand, the effect of Bi2O3 on the chemical durability has been investigated and correlated to the structure using Raman spectral investigation. The relation between the structural changes and composition has been studied by the measurement of the density and glass transition temperature Tg. The obtained results show that the glass transition temperature and chemical properties (water-resistant qualities) increase with increasing compositions of bismuth oxide in all the studied glasses. The structure chains is broken into pyrophosphate groups (P2O7)4- and the P-O-P bonds are depolymerised by the incorporation of distorted Bi(6) units through P-O-Bi bonds. These experimental results agree with a closer structure and act in a manner that Bi2O3 enter the glassy matrix as a network former character