Auger process in CdS/ZnS core-shell quantum dots

Auger processes are investigated for CdS/ZnS core-shell quantum dots. Auger recombination (AR) lifetime and electron relaxation inside the core are computed. Using the effective-mass theory and by solving a three-dimension Schrödinger equation we predict the dependence of Auger relaxation on size of core-shell nanocrystals. We considered in this work different AR processes: the excited electron (EE), excited hole (EH), multiexciton AR type. Likewise, Auger multiexciton recombination rates are predicted for biexciton. Our results show that biexciton AR type is more efficient than the other AR process (excited electron (EE) and excited hole (EH)). We also found that electron Auger relaxation P→S is very efficient in core-shell nanostructures.     

Electrochemical study and electrodeposition of copper in the hydrophobic tri-n-octylmethylammonium chloride ionic liquid media

The electrodeposition of metallic Copper in binary mixture ionic liquid/organic solvent (tri-n-octylmethylammonium chloride (TOMAC))/chloroform (CHCl₃) was investigated. The electrochemical behavior of Cu(II) in TOMAC/CHCl₃ at glassy carbon working electrode at room temperature was studied by cyclic voltammetry and spectroscopy impedance. The results from the cyclic voltammetry showed that the electrodeposition of metallic Cu in the binary mixture ionic liquid/organic solvent was an irreversible process and was controlled by the diffusion of Cu(II) on a glassy carbon working electrode. The average value of αn_α was found to be 0.23 at 25 °C and the diffusion coefficient (D₀) of Cu(II) was calculated to be 7.12 10^− 9 cm²/s at room temperature. The performance of TOMAC ionic liquid such as internal resistance has been investigated with electrochemical impedance spectroscopy (EIS). The scanning electron microscopy (SEM) micrographs was used to observe that the copper plating was moderately dense and contains fine crystallites with average sizes of about 1 μm at room temperature. Energy dispersive X-ray analysis (EDAX) profile showed that the obtained film was copper.     

Isolation of berberine tannate using a chromatography activity-guided fractionation from root bark of Berberis hispanica Boiss. & Reut.

Root bark of Berberis hispanica Boiss. & Reut. constitutes an important source of alkaloids and is traditionally used in Algeria and Morocco in many herbal formulations particularly for the treatment of stomach infections and colon cancer. Activity-guided fractionation of Berberis extract is developed by step-gradient elution on column chromatography followed by preparative HPLC to isolate the most antistaphylococcal compound. Solvent extraction-activity screening indicates that ethanol should be used as the extracting solvent as it has exhibited the highest activity against Staphylococcus aureus(Rosenbach ATCC6538) followed by water extract, whereas no activity is recorded for acetone and hexane extracts. Screening of collected fractions from chromatographic separations indicates that the fraction presenting the highest antistaphylococcal activity is identified as berberine tannate by UV spectrum, melting point measurement and confirmed by liquid chromatography coupled to mass spectrometry (LC/MS). The minimal inhibition concentration value of berberine tannate against S. aureus is evaluated at 5?µg?mL^?1.     

Textural,structural and catalytic behavior of low specific area silica-supported copper catalysts: effect of preparation method

Supported copper catalysts on low surface area silica were prepared by several methods and characterized by AAS, XRD, N₂ adsorption, SEM, H₂-TPR, N₂O titration, TGA-DTA, UV–Vis techniques. Their hydrogenating properties were examined in the gas-phase hydrogenation of benzaldehyde. The analysis of characterization results revealed that the choice of preparation method affected the texture, composition, and structure of the calcined and reduced Cu/SiO₂ catalysts. The dispersion and size distribution of copper species was present in different forms in the catalysts that exhibited low specific surface areas. In gas-phase hydrogenation of benzaldehyde to benzyl alcohol, the catalysts tested at the reaction temperatures of 160 and 200 °C were stable and conducted to a good catalytic activity and benzyl alcohol selectivity ranging between 5 and 39 µmol min^?1 g^?1 and 0–95%, respectively. The activity of the catalysts in gas-phase hydrogenation also depended on the particle size and the nature of copper species formed on low surface area silica.     

Blow-up solutions to the nonlinear Schrödinger equation with oscillating nonlinearities

In this article we investigate the possibility of finite time blow-up in H¹(R²) for solutions to critical and supercritical nonlinear Schrödinger equations with an oscillating nonlinearity. We prove that despite the oscillations some solutions blow up in finite time. Conversely, we observe that for a given initial data oscillations can extend the local existence time of the corresponding solution.     

A pseudo-random numbers generator based on a novel 3D chaotic map with an application to color image encryption

Nonlinear Dynamics - In this work, we propose a novel 3D chaotic map obtained by coupling the piecewise and logistic maps. Showing excellent properties, like a high randomness, a high complexity...     

Regenerative,low-cost and switchable photoelectrochemical sensor for detection of Cu2+ using MnO2-GO heterojunction

Journal of Solid State Electrochemistry - In this work, we investigate the properties of manganese dioxide (MnO2) and graphene oxide (GO) to develop a new photoelectrochemical (PEC) sensor-based...     

Leveraging Multi-Instance RPL Routing Protocol to Enhance the Video Traffic Delivery in IoMT

Wireless Personal Communications - Nowadays, the massive proliferation of real-world multimedia devices has paved the way to the emergence of a new paradigm called the Internet of Multimedia Things...     

Synthesis and characterization of the azido-bound five-coordinate high-spin iron(II) “picket fence” porphyrin complex

An Fe(II)-azido five-coordinate picket fence porphyrin complex with the formula [Na(2,2,2-crypt)][Fe^II(TpivPP)(N₃)] · 3C₆H₅Cl (TpivPP = α,α,α,α-tetrakis(o-pivalamidophenyl)porphinato, known as a picket fence porphyrin, and 2,2,2-crypt is the cryptand-222) has been synthesized and characterized. The synthesis utilizes cryptand-222 to solubilize sodium azide in the preparation procedure. The UV–Vis and IR spectroscopic data are consistent with an azido ferrous porphyrinate. The X-ray structural analysis and the Mössbauer results indicate that the ion complex [Fe^II(TpivPP)(N₃)]⁻ is high-spin and has the (d_xy)²(d_xz)¹(d_yz)¹(d_z2)¹(d_x2-y2)¹$({\text{d}}_{\mathit{xy}}{)}^2({\text{d}}_{\mathit{xz}}{)}^1({\text{d}}_{\mathit{yz}}{)}^1({\text{d}}_{z^2}{)}^1({\text{d}}_{x^2-y^2}{)}^1$ ground state electronic configuration.     

Development and validation of a turbidimetry method for hydrogen sulphide evaluation in effluents of phosphoric acid production unit

The aim of this study was to develop and validate a simple, new and efficient method for the analysis of hydrogen sulphide (H₂S) released from the effluents of phosphoric acid production units. H₂S sampling was performed by absorption of the industrial gas into a cadmium acetate absorbing solution. The formed cadmium sulphide (CdS), as a result of a chemical reaction, was analysed by turbidimetry. A methodical validation study of the proposed method was performed according to the requirements of ISO 17025 standards. The proposed method was demonstrated to be precise, linear and accurate over a concentration range of 6.91–92.16 mg/l. Detection and quantification limits were equal to 5.09 mg/l and 6.91 mg/l, respectively. Sample analysis had to be performed within 48 h of the sampling step. The turbidimetry method was applied successfully to the industrial gaseous effluents and can be considered as an economical alternative to the iodometric method.