Preparation of zinc sodium polyphosphates glasses from coacervates precursors. Characterisation of the obtained glasses, and their applications

A soft chemistry route is described to obtain glasses in the P₂O₅–Na₂O–ZnO–H₂O. It is based on the addition of zinc salts to coacervates prepared from sodium polyphosphate. The processing of these coacervates leads to polyphosphate glasses with the same properties as those of glasses prepared in the classical way. So far, little work has been implemented in this system using ‘coacervate route’. However, it makes an attractive method for coating and joining processes on the industrial scale. As the anion associated to zinc may take part in the adhesion mechanism, coacervate formation has been studied using zinc chloride, nitrate and sulphate as starting materials. The physical properties of the glasses obtained by this method are reported and potential applications of zinc and silver coacervate are described.     

Experimental and numerical analysis of automotive gearbox rattle noise

The aim of this work is to characterize the rattle noise of automotive gearboxes, resulting from impacts between toothed wheels of unselected gear ratios. These stereo-mechanical impacts are modeled by a coefficient of restitution which describes damping during the squeezing of the lubricant film for approaching surfaces, and the elastic deformation of impacting bodies. The dynamic response of the loose gear first depends on the design parameters and the engine operating conditions. The unknown parameters are the drag torque and the coefficient of restitution. They are identified experimentally through implementation of two optical encoders in an actual automotive gearbox and the operation of a specific test bench which replicates the automotive power train. Models of the different drag torque sources are validated from analysis of the free damped response of the driveline. The coefficient of restitution and its probability density function are measured from experiments under stationary operating conditions. A nonlinear model is built. The dynamic response of the loose gear depends on the dimensionless backlash, the coefficient of restitution and a dimensionless parameter proposed to describe the rattle excitation level. Experiments under controlled excitation are performed to validate the assumptions, to confirm the ability of the parameter proposed to describe the rattle noise threshold, and to characterize the dynamic response. The nonlinear model predictions are fitted with the drag torque and coefficient of restitution previously identified. They are compared with measurements to demonstrate the ability of the model to predict gear rattle for any loose gear, any gearbox and any operating condition.     

Effects of Halogen Bonding in Chemical Activity of Lead(II) Electron Pair: Sonochemical Synthesis,Structural Studies,and Thermal Analysis of Novel Lead(II) Nano Coordination Polymer

The nanoflower lead(II) coordination compound {[Pb(phen)(μ‐CH₃COO)][PF₆]}_n ( 1 ) (phen = 1,10‐phenanthroline) was synthesized by a sonochemical method. The nanostructure was characterized by using scanning electron microscopy (SEM), X‐ray powder diffraction, elemental analysis, and thermal analysis. The single‐crystal X‐ray structure shows that the overall structure of 1 is a 1D coordination polymer. Complex 1 has a bridging acetate pathway. Three halogen bonds observed in the structure and the strong halogen bonding of F–Pb causes chemical activity of the lead electron pair. This is further extended into a 3D supramolecular structure by weak π–π intermolecular interactions. The coordination number of the lead(II) ions is six, resulting in PbN₂O₄. PbO nanoparticles were obtained by the thermolysis of 1 at 180 °C with oleic acid as a surfactant. The morphology and size of the prepared PbO nanoparticles were further observed using scanning electron (SEM) and transmission electron microscopy (TEM), and were analyzed by X‐ray photoelectron spectroscopy (XPS).     

Structural study of tungstate fluorophosphate glasses by Raman and X-ray absorption spectroscopy

Transparent glasses were synthesized in the NaPO₃-BaF₂-WO₃ ternary system and several structural characterizations were performed by X-ray absorption spectroscopy (XANES) at the tungsten L_I and L_III absorption edges and by Raman spectroscopy. Special attention was paid to the coordination state of tungsten atoms in the vitreous network.XANES investigations showed that tungsten atoms are only six-fold coordinated (octahedra WO₆) and that these glasses are free of tungstate tetrahedra (WO₄).In addition, Raman spectroscopy allowed to identify a break in the linear phosphate chains as the amount of WO₃ increases and the formation of P-O-W bonds in the vitreous network indicating the modifier behavior of WO₆ octahedra in the glass network. Based on XANES data, we suggested a new attribution of several Raman absorption bands which allowed to identify the presence of W-O⁻ and WO terminal bonds and a progressive apparition of W-O-W bridging bonds for the most WO₃ concentrated samples (?30% molar) due to the formation of WO₆ clusters.     

Determination of olive oil acidity by CE

In this work, a CE method for the determination of olive oil acidity was proposed. The method was based on an ethanolic extraction (at 60 degrees C) of the oil long-chain free fatty acids (LC-FFAs) components followed by CE determination in pH 6.86 phosphate buffer at 15 mmol/L concentration containing 4 mmol/L sodium dodecylbenzenesulfonate (SDBS), 10 mmol/L polyoxyethylene 23 lauryl ether (Brij 35), 2% v/v 1-octanol and 45% v/v ACN under indirect UV detection at 224 nm. Although this electrolyte promoted baseline separation of myristic acid (C14:0) (internal standard (IS)) and olive oil major components (palmitic acid (C16:0), oleic acid (C18:1c) and linoleic acid (C18:2cc)) in less than 8 min, after a few injections, the electropherogram profiles were severely altered (peak broadening, migration time shifts, etc.) and the current increased substantially. An adsorption study was conducted revealing that the dissolution of the capillary external polyimide coating during the electrophoretic run caused the detrimental effect. After removal of the capillary tip coating, ten consecutive injections could be performed without any disturbances and this simple procedure was, therefore, implemented during quantitative purposes. The reliability of the proposed method was further investigated by the determination of acidity of an extra virgin olive oil sample in comparison to the established methodology (AOCS method Ca 5a-40, alkaline volumetric titration (AVT)). No statistical differences were found within 95% confidence level. A % acidity of 0.39 +/- 0.02 was found for the olive oil sample under consideration.     

Theoretical study on the small carbon nano-ladders

1,3-Butadiyne, 1,3,5-hexatriyne, 1,3,5,7-octatetrayne, and 1,3,5,7,9-decapentayne are small oligomeric forms of acetylene. These oligomers participate in cyclization reactions to form ladder-like structures. Enthalpies, ?H, and Gibbs free energies, ?G, of the cyclization reactions were calculated employing MP2 and B3LYP methods. The calculated ?H and ?G were positive, and their variation versus carbon atoms number, n, was fitted in linear functions as ?H(n) = a+bn. The calculations were performed on the structures with carbon numbers up to 20. Also, consecutive cyclization reactions between acetylene molecules were studied. During these consecutive reactions, two different structures, zigzag-ladder-like and cyclic molecules with tetragonal rings, were produced. Among the cyclic structures, the hexagonal form was the most stable structure. The calculated ?H and ?G of formation of zigzag-ladder-like molecules were excellently fitted in linear functions. The obtained functions for ?H and ?G calculated by MP2 method are ?H(n) = 139.67?126.44n and ?G(n) = 80.987?75.684n, respectively.     

Preparation of poly(acrylamide)/nanoclay organic-inorganic hybrid nanoparticles with average size of ∼250 nm via inverse Pickering emulsion polymerization

In this study, the preparation of poly(acrylamide)/nanoclay organic-inorganic hybrid nanoparticles via surfactant-free inverse emulsion polymerization by using organically modified clay platelets as stabilizers was discussed. Colloidally stable inverse Pickering emulsions of aqueous acrylamide solution in cyclohexane (solvent) stabilized by hydrophobic Cloisite 20A (MMT20) were prepared. Polymerization was carried out via 2,2′-azobis(isobutyronitrile) and composite particles with an average size of ～250 nm were obtained. The effect of initiator and solvent type on the stability, size, size distribution, and morphology of the produced composite particles was examined. It was observed that in the presence of xylene as solvent, particles with bigger sizes and broader size distribution were obtained. Furthermore, using an ionic initiator resulted in a slight coagulation during polymerization and smaller particles. Moreover, the effect of various polymerization conditions such as temperature, initiator, and crosslinking agent concentration and clay content on the polymerization rate was evaluated. The experimental results showed that polymerization rate increases with an increase in polymerization temperature, crosslinking agent concentration, and initiator content. However, increasing in clay content results in a lower polymerization rate.     

Oleochemical‐Tethered SBA‐15‐Type Silicates with Tunable Nanoscopic Order,Carboxylic Surface,and Hydrophobic Framework: Cellular Toxicity,Hemolysis, and Antibacterial Activity

Novel silicates were prepared by using silylated natural fatty acids (derived from triglyceride renewable oils) as co‐condensing reagents in presence of tetraethyl orthosilicate (TEOS) and the triblock copolymer, pluronic P123, as a structure directing agent. A series of carboxylic acid functionalized SBA‐15‐type mesoporous silicates were obtained with tunable nanoscopic order and reactive functional groups that allow the conjugation of amino probes by peptide coupling. Photophysical studies of the covalently linked aminopyrene substantiated that the internal framework of these materials have pronounced hydrophobicity. Moreover, phase separation that can emanate from the bulkiness of the starting fatty silanes has been ruled out owing to the absence of excimers after aminopyrene grafting. The hemotoxicity, cytotoxicity, and antimicrobial activity of these novel silicates were then evaluated. Without discrimination, the functionalized silicates show a significant decrease of red blood cell hemolysis as compared to bare SBA‐15‐silica material. Within the modified silicate series, germanium‐free mesoporous silicates induce only a slight decrease in cell viability and, more interestingly, they exhibit negligible hemolytic effect. Moreover, increasing their concentration in the medium reduces the concentration of released hemoglobin as a result of Hb adsorption. Promising antimicrobial properties were also observed for these silicates with a slight dependency on whether phenylgermanium fragments were present within the silicate framework.     

Surveying FDA-approved drugs as new potential inhibitors of N-cadherin protein: a virtual screening approach

Since N-cadherin protein plays a remarkable role in cancer metastasis and tumor growth and progression, finding new effective inhibitors of this protein can be of high importance in cancer treatment. Nevertheless, few molecules have been introduced to inhibit N-cadherin protein to date. In this work, in order to find and present potent inhibitors, 3358 FDA-approved small molecules were docked against N-cadherin protein. All complexes with binding energy ??9 to ??8 kcal/mol were selected for protein-ligand interaction analysis. In the following, Tanimoto coefficient (T_c) was calculated for those molecules that established appropriate interactions with N-cadherin in order to compute the similarity score between them. Afterwards, molecular dynamics simulation and free energy calculations were done to estimate the stability and ability of the chosen ligands in complex with the target protein. Finally, seven small molecules among 3358 FDA-approved were suggested as potential inhibitors of N-cadherin protein.

     

Synthesis of New Fused and Spiro Heterocyclic Systems from 3,5‐Pyrazolidinediones

4‐Bromo‐1‐phenyl‐3,5‐pyrazolidinedione 2 reacted with different nucleophilic reagents to give the corresponding 4‐substituted derivatives 3–8 . The cyclized compounds 9–11 were achieved on refluxing compounds 3 , 4 or 6_a in glacial acetic acid or diphenyl ether. 4,4‐Dibromo‐1‐phenyl‐3,5‐pyrazolidinedione 12 reacted with the proper bidentates to give the corresponding spiro 3,5‐pyrazolidinediones 13–15 , respectively. The 4‐aralkylidine derivatives 16_a‐c , were subjected to Mannich reaction to give Mannich bases 17_a‐c‐22_a‐c , respectively. 4‐(p‐Methylphenylaminomethylidine)‐1‐phenyl‐3,5‐pyrazolidinedione 23 or 4‐(p‐methylphenylazo)‐1‐phenyl‐3,5‐pyrazolidinedione 29 were prepared and reacted with active nitriles, cyclic ketones and N,S‐acetals to give pyrano[2,3‐c]pyrazole, pyrazolo[4′,3′:5,6]pyrano[2,3‐c]pyrazole, spiropyrazole‐4,3′‐pyrazole and spiropyrazole‐4,3′‐[1,2,4]triazolane derivatives 24–34 , respectively.