Excimer laser-induced crystallization of CdSe thin films

We have investigated ArF (λ=193 nm) excimer laser-induced crystallization of amorphous CdSe semiconductor thin films. The crystallization has been monitored by a related photoluminescence emission in the free-exciton and defect-band transition regions. For different irradiation conditions, we have observed formation of nanorods, up to 2 μm long, as well as the formation of arrays of CdSe nanobeads with a narrow size distribution and characteristic dimensions corresponding to λ/2 and λ/8. The successful crystallization has also been confirmed by confocal Raman spectroscopy.     

New lead (II) selective membrane potentiometric sensors based on chiral 2,6-bis-pyridinecarboximide derivatives

New membrane sensors with cylindrical configuration for lead (II) ions are described based on the use of three newly synthesized pyridine carboximide derivatives as neutral ionophores in plasticized PVC membranes. The sensors exhibit significantly enhanced response towards lead (II) ions over the concentration range 4×10⁻⁶-1×10⁻² mol l⁻¹ at pH 4.5-7 with a lower detection limit of 0.4-3.7 μg ml⁻¹. The sensors display near-Nernstian slope of 26.0-33.1 mV per decade for Pb(II) ions. Effects of plasticizers, lipophilic salts and various foreign common ions are tested. The sensors show long life span, good selectivity for Pb(II) over a wide variety of other metal ions, long term stability, high reproducibility, and fast response. Validation of the method by measuring the lower detection limit, range, accuracy, precision, repeatability and between-day-variability reveals good performance characteristics of the proposed sensors. The sensors are used for direct determination of lead in stack emissions of lead smelters, assay of lead in rocks and monitoring of potentiometric titration of Pb(II) with EDTA. The results obtained agree fairly well with data obtained by atomic absorption spectrometry.     

Ni(II)-selective PVC membrane sensor based on 1,2,4-triazole bis Schiff base ionophore: Synthesis,characterization and application for potentiometric titration of Ni2+ ions against EDTA

This study involves the preparation and investigation of a novel and highly selective poly(vinyl chloride)-based membrane of 2-((5-(2-hydroxy-3-methoxybenzylideneamino)-2H-1,2,4-triazol-3-ylimino)methyl)-6-methoxyphenol Schiff base ligand (HMBT), which is a neutral ionophore with sodium tetraphenyl borate (STB) in the form of an excluder and o-nitrophenyloctyl ether (o-NPOE) in the form of solvent mediators (plasticizing) as a Ni(II)-selective electrode. The observation of optimal performance was done wherein the membrane was shown to have the HMBT–PVC–NPOE-STB composition of 4:32:63:1.It worked effectively across a broad range of concentration (1.0 × 10^?8 to 1.0 × 10^?2 mol L^?1). Meanwhile, the Nernstian slope was recorded as 29.3 mV per decade of activity between pH 3.0 and 8.0. The response time of this electrode was fast at 11 s which was used for a span of 100 days with sound reproducibility. According to the selectivity coefficients for trivalent, divalent, and monovalent cations, excellent selectivity was indicated for Ni(II) ions across a large number of citations, whereas no interference was caused by anions like PO₄^3?, SO₄^2? and Cl^?. The proposed method in this study was applied successfully to determine Ni(II) content in different samples of water, obtaining suitable recoveries. Additionally, the probed sensor is utilized as indicator electrode when considering Ni²⁺ ion potentiometric titration against EDTA. In addition, the chelate’s geometry and structure of the complex formed between Ni²⁺ ions and HMBT, abbreviated as HMBT-Ni₂, was evaluated by separating the solid product. Complex structure was confirmed based on alternative analytical and spectral methods to be structured in the bimetallic form with the formula [Ni₂(HMBT)(H₂O)₂ Cl₂]. The diamagnetic nature of the complex, which was concluded from the room temperature magnetic moment measurement combined with the UV–Vis measurement, suggested the square planar geometry around the Ni centers.     

A note on an accelerating finite energy Airy beam

A recently derived Airy beam solution to the (1+1)D paraxial equation is shown to obey two salient properties characterizing arbitrary finite energy solutions associated with second-order diffraction; the centroid of the beam is a linear function of the range and its variance varies quadratically in range. Some insight is provided regarding the local acceleration dynamics of the beam. It is shown, specifically, that the interpretation of this beam as accelerating, i.e., one characterized by a nonlinear lateral shift, depends significantly on the parameter a entering into the solution.     

Spectral, electrical conductivity and biological activity properties of some new azopyrimidine derivatives and their complexes

The electronic absorption spectra of 5-(o-substituted phenylazo)-6-amino-2-thiouracils and 6-(o-substituted phenylazo)-5-aminouracils containing different substituents are studied at different pH's. The dissociation constants are evaluated and discussed. Phenomenon of tautomerism is more supported by (1)H NMR and (13)C NMR spectra. The electrical conductivity of some ligands and their Co(II), Ni(II) and Cu(II) complexes in the temperature range 293-150K favoured their semiconducting properties where the metal ion forms a bridge to facilitate the flow of the current. The biological activity of some ligands and their complexes are tested against a number of Gram-positive and Gram-negative bacteria. The results showed that some of the compounds have a well considerable activity against some of the organisms.     

Clifford Algebra Formulation of an Electromagnetic Charge-Current Wave Theory

In this work, a Clifford algebra approach is used to introduce a charge-current wave structure governed by a Maxwell-like set of equations. A known spinor representation of the electromagnetic field intensities is utilized to recast the equations governing the charge-current densities in a Dirac-like spinor form. Energy-momentum considerations lead to a generalization of the Maxwell electromagnetic symmetric energy-momentum tensor. The generalized tensor includes new terms that represent contributions from the charge-current densities. Stationary spherical modal solutions representing the charge-current densities and the associated self-fields are derived. The use of a Clifford type dependence on time results in a distinct symmetry between the magnetic and electric components. It is shown that, for such spherical modes, the components of the force density deduced from the generalized energy-momentum tensor can vanish under certain conditions.     

MD Simulation Studies for Selective Phytochemicals as Potential Inhibitors against Major Biological Targets of Diabetic Nephropathy

Diabetes is emerging as an epidemic and is becoming a public health concern worldwide. Diabetic nephropathy is one of the serious complications of diabetes, and about 40% of individuals with diabetes develop diabetic nephropathy. The consistent feature of diabetes and its associated nephropathy is hyperglycemia, and in some cases, hyperamylinemia. Currently, the treatment includes the use of medication for blood pressure control, sugar control, and cholesterol control, and in the later stage requires dialysis and kidney transplantation, making the management of this complication very difficult. Bioactive compounds, herbal medicines, and extracts are extensively used in the treatment and prevention of several diseases, and some are reported to be efficacious in diabetes too. Therefore, in this study, we tried to identify the therapeutic potential of phytochemicals used in in silico docking and molecular dynamic simulation studies using a library of 5284 phytochemicals against the two potential targets of type 2 diabetes-associated nephropathy. We identified two phytochemicals (i.e., gentisic acid and michelalbine) that target human amylin peptide and dipeptidyl peptidase-4, respectively, with good binding affinity. These phytochemicals can be further evaluated using in vitro and in vivo studies for their anti-hyperglycemia and anti-hyperamylinemia effects.     

Nanolipogel Loaded with Tea Tree Oil for the Management of Burn: GC-MS Analysis,In Vitro and In Vivo Evaluation

The GC-MS analysis of tea tree oil (TTO) revealed 38 volatile components with sesquiterpene hydrocarbons (43.56%) and alcohols (41.03%) as major detected classes. TTO efficacy is masked by its hydrophobicity; nanoencapsulation can address this drawback. The results showed that TTO-loaded solid lipid nanoparticles (SLN1), composed of glyceryl monostearate (2% w/w) and Poloxamer188 (5% w/w), was spherical in shape with a core-shell microstructure. TTO-SLN1 showed a high entrapment efficiency (96.26 ± 2.3%), small particle size (235.0 ± 20.4 nm), low polydispersity index (0.31 ± 0.01), and high negative Zeta potential (−32 mV). Moreover, it exhibited a faster active agent release (almost complete within 4 h) compared to other formulated TTO-SLNs as well as the plain oil. TTO-SLN1 was then incorporated into cellulose nanofibers gel, isolated from sugarcane bagasse, to form the ‘TTO-loaded nanolipogel’ which had a shear-thinning behavior. Second-degree thermal injuries were induced in Wistar rats, then the burned skin areas were treated daily for 7 days with the TTO-loaded nanolipogel compared to the unmedicated nanolipogel, the TTO-loaded conventional gel, and the normal saline (control). The measurement of burn contraction proved that TTO-loaded nanolipogel exhibited a significantly accelerated skin healing, this was confirmed by histopathological examination as well as quantitative assessment of inflammatory infiltrate. This study highlighted the success of the proposed nanotechnology approach in improving the efficacy of TTO used for the repair of skin damage induced by burns.     

Numerical simulation and stability analysis of a novel reaction–diffusion COVID-19 model

Nonlinear Dynamics - In this study, a novel reaction–diffusion model for the spread of the new coronavirus (COVID-19) is investigated. The model is a spatial extension of the recent COVID-19...     

Synthesis of Some New Substituted Thieno[2,3-d]pyrimidine Derivatives as Antimicrobial Agents

Russian Journal of General Chemistry - A series of thieno-pyrimidine derivatives are synthesized from 5′-amino-2,3′-bithiophene-4′-carboxylate via the corresponding intermediate...