Efficient catalytic degradation of single and binary azo dyes by a novel triple nanocomposite of Mn3O4/Ag/SiO2

The strategy of structurally integrating noble metal and metal oxides is expected to offer exceptional opportunities toward emerging functions of all. We report the creation of an efficient hetero-structured nanocatalyst consisting of Mn₃O₄ core, SiO₂ shell impregnated with noble Ag nanoparticles. The triple nanocatalyst Mn₃O₄/Ag/SiO₂ was synthesized by using a facile three-step approach to disperse Ag nanoparticles between the surfaces of functionalized Mn₃O₄ and SiO₂. The physicochemical structural characterization was performed by XRD and FTIR. The surface morphologies were observed by SEM and TEM. The EDX measurements confirmed the composition of the composite. The nanocomposite has been used as a catalyst for the degradation of Direct blue 78 in the presence of sodium borohydride (NaBH₄). It has a drastic catalytic effect as compared to Mn₃O₄/Ag and Mn₃O₄. The rate constant of Direct blue 78 reduction followed the order: Mn₃O₄/Ag/SiO₂ (0.25166 min⁻¹) > Mn₃O₄/Ag (0.07971 min⁻¹) > Mn₃O₄ (0.00947 min⁻¹). The effects of different reaction conditions of the catalytic reaction have been determined. The catalytic activity of the as- synthesized nanocomposite was examined for the binary dyes system by incorporation of an additional dye (Sunset yellow). Its influence on the degradation rate and efficiency of Direct blue 78 was investigated. The nanocatalyst exhibited excellent catalytic activity towards the complete degradation of both the Direct blue 78 and Sunset yellow. The degradation percentage for these dyes reached 99.33 and 94.68%, respectively. The recovery and reusability of the Mn₃O₄/Ag/SiO₂ nanocomposite was studied in the reduction reaction of Direct blue 78. Five consecutive recovery reaction cycles were performed. They revealed high stability and constant efficiency of the catalyst for four cycles.     

Colloidal Ag@Pd core–shell nanoparticles showing fast catalytic eradication of dyes from water and excellent antimicrobial behavior

Research on Chemical Intermediates - Colloidal Ag@Pd core–shell nanoparticles (NPs) were synthesized in aqueous medium following the citrate method. The progress of formation of the...     

Characterization of a heavily corroded bronze statue from Pharaonic Egypt

The current study aims to characterize a heavily corroded bronze statue from Pharaonic Egypt, in terms of the morphology and mechanism of corrosion. The characterization was carried out by a combination of methods, including the scanning electron microscope equipped with energy dispersive X-ray spectroscopy (SEM–EDS), USB digital microscope, X-ray micro-diffraction, and Raman micro-spectroscopy. Insights into the morphology and corrosion mechanisms of two corrosion stages are presented. Specifically, the metallic-wall layer was first converted into grayish-brown corrosion mottled with green and gray spots in the central part, in which a greenish-white corrosion phase was formed in the second stage. The EDS analysis of the greenish-white phase revealed the predominance of tin, copper, oxygen, and carbon and a low chlorine content. The greenish-white phase consisted of four corrosion products: romarchite, cassiterite, malachite, and a small amount of atacamite. The morphology developed upon corrosion was attributed to the selective dissolution and depletion of copper in the central layer, internal oxidation of tin, and conversion of cuprite into malachite. Moreover, the usual bronze corrosion products were formed as a superficial layer on the statue.     

Synthesis and antimicrobial evaluation of new 2-pyridinone and 2-iminochromene derivatives containing morpholine moiety

As trail to overcome on the antimicrobial drug-resistance problems, new functionalized 2-pyridinone and 2-iminochromene derivatives bearing morpholine moiety were designed and synthesized. The 2-pyridinone derivatives were obtained through the cyclization of cyanoacetohydrazone of 4-morpholinylacetophenone with 1,3-dicarbonyl compounds, α,β-unsaturated nitriles or 2-(arylidene)malononitriles. The 2-iminochromene derivatives were synthesized through the ring closure of cyanoacetohydrazonewith salicylaldehyde derivatives. The antibacterial and antifungal activities for the synthesized 2-pyridinone and 2-iminochromene derivatives were investigated. Most of the tested compounds showed moderate activity against P. vulgaris. Compounds 4a,b and 5a,b showed moderate activity against G −ve bacteria. All iminochromene derivatives showed moderate activity against C. albicans. Compound 8c was the most active compound.     

Phytochemical Profiling of Lavandula coronopifolia Poir. Aerial Parts Extract and Its Larvicidal,Antibacterial, and Antibiofilm Activity Against Pseudomonas aeruginosa

Infections associated with the emergence of multidrug resistance and mosquito-borne diseases have resulted in serious crises associated with high mortality and left behind a huge socioeconomic burden. The chemical investigation of Lavandula coronopifolia aerial parts extract using HPLC–MS/MS led to the tentative identification of 46 compounds belonging to phenolic acids, flavonoids and their glycosides, and biflavonoids. The extract displayed larvicidal activity against Culex pipiens larvae (LC₅₀ = 29.08 µg/mL at 72 h). It significantly inhibited cytochrome P-450 monooxygenase (CYP450), acetylcholinesterase (AChE), and carboxylesterase (CarE) enzymes with the comparable pattern to the control group, which could explain the mode of larvae toxification. The extract also inhibited the biofilm formation of Pseudomonas aeruginosa by 17–38% at different Minimum Inhibitory Concentrations (MICs) (0.5–0.125 mg/mL) while the activity was doubled when combined with ciprofloxacin (ratio = 1:1 v:v). In conclusion, the wild plant, L. coronopifolia, can be considered a promising natural source against resistant bacteria and infectious carriers.     

On support properties of functions and their Jacobi transform

The qualitative uncertainty principle proved by Benedicks asserts that f and its Fourier transform \(\hat f\) cannot both concentrated in subsets of finite Lebesgue measure. In this paper we obtain some uncertainty principles concerning sets of finite measure in the Jacobi setting.     

Flow Regimes of Interaction of a Turbulent Plane Jet into a Rectangular Cavity: Experimental Approach and Numerical Modelling

The present work is devoted to the experimental and numerical study ofthe interaction of a turbulent plane jet with a rectangular cavity.Several flow regimes have been found to occur: the non-oscillationregime, the stable oscillation regime and an unstable oscillationregime. The first two regimes have been particularly considered. Theexperimental study has been carried out using hot wire anemometry andsome visualisations. The numerical predictions based on statisticalmodelling have been made using on the one hand the standard k– model and on the other hand a two-scales split spectrum model. The structuralproperties of the flow have been described for the different situations.For the oscillatory regime, a parametrical study allowed to determinethe influence of the jet exit location and the Reynolds number on thefrequency of the jet flapping. The one point closures have been able topredict the oscillatory regime, and in particular the two-scales modelled to improved results because better account is taken of lag effectsin unsteady non-equilibrium situations.     

3D-pharmacophore study molecular docking and synthesis of pyrido[2,3-d]pyrimidine-4(1H) dione derivatives with in vitro potential anticancer and antioxidant activities

Some poly functionalized heterocyclic-compounds containing pyridine-moieties were readily assembled by combining differently functionalized pyridopyrimidine-6-carbonitrile derivatives 1a,b with different electrophilic and nucleophilic reagents via short synthetic routes. The structures of the prepared derivatives were ascertained from their-spectral-and elemental analyses. Some of the synthesized compounds were tested as plausible antitumor agents. Most of those tested compounds likes 7 , 9 , 10 , 11a showed cytotoxic potencies against different tumor cell lines. In addition, the assessments for their antioxidant activities have also been done and compound 9 exhibited the highest antioxidant activity while compounds 7 and 10 showed moderate activities. Finally, molecular docking studies were carried out which favorably indicated a high support for the experimental-results.     

Polymer complexes. LXXVI. Synthesis,characterization, CT‐DNA binding,molecular docking and thermal studies of sulfoxine polymer complexes

Novel polymer complexes of 8‐hydroxyquinoline‐5‐sulfonic acid hydrate ( H ₂ L ) with Cu²⁺, Co²⁺ and Ni²⁺ chloride were prepared and characterized. Microanalysis, magnetic susceptibility, IR spectra, electron spin resonance, mass spectra, X‐ray, molar conductance, thermal, and UV–Vis spectra studies have been used to confirm the structure of the prepared polymer complexes. The molecular and electronic structures of the hydrogen bond conformers for ligand ( H ₂ L ) were optimized theoretically and the quantum chemical parameters were calculated. On the basis of elemental and IR data, the chemical structure of metal chelates commensurate that the tri‐dentate (H₂L) coordinate to metal chlorides through oxygen atom of phenolic OH and oxygen atom of SO₃‐H group by replacing H atoms and nitrogen of the quinoline ring. The magnetic studies suggested the octahedral geometrical structure for all produced polymer complexes with general formula {[ML (OH₂)₃] .xH₂O}_n (M = Cu²⁺, x = 1.; Co²⁺, x = 2 and Ni²⁺, x = 2) in molar ratio (1:1). Coats–Redfern and Horowitz–Metzger methods have been used for calculating the activation thermodynamic parameters of the thermal decomposition for H ₂ L and its polymer complexes. The interaction between H ₂ L and its transition metal complexes with the calf thymus DNA (CT‐DNA) was determined by UV–Vis spectra. Binding efficiency between H ₂ L with the receptors of the prostate cancer (PDB code 2Q7L Hormone) and the breast cancer (PDB code 1JNX Gene regulation) was studied by molecular docking. The inhibition behaviour of H ₂ L against the corrosion of carbon steel / HCl (2 M) solution was studied by weight loss, Tafel polarisation, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The adsorption isotherm was found to be Friendlish isotherm. The morphology of inhibited carbon steel? s surface was studied using scanning electron microscope (SEM) and energy dispersive X‐ray spectroscopy (EDS).     

Determination of primordial radionuclide concentrations in UAE groundwater using high-resolution gamma-ray spectrometry

Journal of Radioanalytical and Nuclear Chemistry - Groundwater is the most valuable resource in arid regions, such as UAE. Estimations of natural radionuclide concentrations are important to...