Titanium Carbide (Ti3C2Tx) MXene Ornamented with Palladium Nanoparticles for Electrochemical CO Oxidation

Titanium carbide (Ti₃C₂T_x) MXene possesses various unique physicochemical and catalytic properties. However, the electrochemical CO oxidation performance is not yet addressed experimentally. Herein, Ti₃C₂T_x (T_X=OH, O, and F) ordered and exfoliated two-dimensional nanosheets ornamented with semi-spherical palladium nanoparticles (2.5 Wt. %) with an average diameter of (10±1 nm) (denoted as Pd/Ti₃C₂T_x) is rationally designed for the electrochemical CO oxidation. The fabrication process is based on the selective chemical etching of Ti₃AlC₂ and delamination under sonication to form Ti₃C₂Tx nanosheets that are used as a substrate and reducing agent for supporting in situ growth of Pd nanoparticles via impregnation with Pd salt. Interestingly, Pd-free Ti₃C₂T_x displayed inferior CO oxidation activity, while Pd/Ti₃C₂T_x enhanced the CO oxidation activity substantially. This is attributed to the combination of outstanding physicochemical properties of Ti₃C₂T_x and the catalytic merits of Pd nanoparticles.     

Kinetics of aquation of trans-dichlorobis(N,N′-dimethylethylenediamine)cobalt(III) ion in water–methanol in water–propan-2-ol media

The complex trans-[Co(dmen)2Cl2]Cl (dmen=N,N-dimethylethylenediamine) has been prepared and characterized by elemental analysis, u.v.-vis. and i.r. spectra. The kinetics of the primary aquation of trans-[Co(dmen)2Cl2] in H2O, H2O–MeOH and H2O–i-PrOH have been examined over a wide range of solvent compositions and temperatures (40–55°C). Plots of rate constants (log k) versus the reciprocal of the dielectric constant of the medium (Ds–1) and Grunwald–Winstein values of the solvent (Y) were found to be non-linear. The variation of enthalpies (H) and entropies (S) of activation with solvent composition has been determined. Plots of H or S versus the mole fraction of each solvent exhibit extrema at x2=ca. 0.16 and 0.27 for MeOH and at x2=ca. 0.03 and 0.14 for i-PrOH. Furthermore, the cycle relating the free energy of activation in H2O to that in H2O–co-solvent shows that the stabilizing influence of the changes in the solvent structure is greater on the emergent five-coordinate cation in the transition state than that on the complex ion in the initial state, with the difference becoming greater as the mole fraction of the co-solvent increases.     

Thermal analysis in swirling flow of titanium dioxide–aluminum oxide water hybrid nanofluid over a rotating cylinder

Journal of Thermal Analysis and Calorimetry - The purpose of this study is to examine the flow features and heat transfer in the presence of nanoparticles which are used to enhance the...     

Physical aging phenomena in silica and glass beads filled elastomers (EPDM)

The physical aging concept is generally used to explain the typical behavior of amorphous glassy materials such as amorphous polymers. It can be easily evidenced by measuring the effect of a static deformation on the dynamic mechanical properties. In this paper, an attempt is made to determine the “glassy” behavior of elastomeric EPDM chains when they are confined in the vicinity of the filler (glass beads, silicas) surface. It is demonstrated that glassy behavior and physical aging phenomena are detected even with a filled elastomer. Furthermore, the influence of the filler volume fraction, the filler nature and of filler surface treatments with silanes were studied. Finally, an original attempt is made to explain filler-rubber reinforcement by a kind of bimodal network created from linkages between a densely packed interfacial region and the outer loose matrix.     

Pyridazine,oxazine, pyrrole,and pyrrolo[1,2‐a]quinazoline derivatives from malononitrile dimer

2‐Amino‐1,1,3‐tricyano‐3‐bromopropene was obtained from bromination of 2‐amino‐1,1,3‐tricyanopropene (malononitrile dimer) with N‐bromosuccinimide. This bromo derivative reacts with hydrazine hydrate, phenyl hydrazine, and hydroxylamine hydrochloride to afford pyridazine and oxazine derivatives, respectively. In base‐catalyzed reactions with primary aromatic amines and anthranilic acid derivatives, it produces N‐aryl pyrrol‐3,5‐dicarbonitrile and pyrrolo[1,2‐a]quinazolin‐5‐imine, or pyrrolo[1,2‐a]quinazolin‐5‐one derivatives, respectively. The structures of the newly synthesized heterocycles were established on the basis of elemental analyses and spectral data. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:612–616, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10199     

Functionally substituted alkylbenzotriazoles: Reactivity of alkylbenzotriazoles toward electrophilic and nucleophilic reagents

The reactivity of benzotriazolylacetone toward a variety of carbon and nitrogen electrophiles is reported. Several novel azolylbenzotriazoles as well as benzotriazolyl‐cinnolines have been synthesized. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:141–145, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10009     

Study of the migration of additives from plasticized PVC

The aim of this paper is to study the interactions between packaging and food. For that purpose, additives were first characterized. Kinetic studies of their specific migrations have been carried out by using different analytical methods such as gas chromatography, Fourier transform infrared spectroscopy, atomic absorption spectrometry and differential scanning calorimetric analysis. The influence of various parameters such as temperature, agitation, nature of food simulant and initial concentration of plasticizer was considered.     

Supramolecular Thermotropic Liquid Crystalline Materials with Nematic Mesophase Based on Methylated Hyperbranched Polyethylenimine and Mesogenic Carboxylic Acid

Summary: Supramolecular interaction of fully methylated hyperbranched polyethylenimines (PEI) with a mesogen‐based carboxylic acid, 5‐(p‐cyanobiphenoxy)pentanoic acid, results in the formation of supramolecular complexes exhibiting thermotropic liquid crystalline (LC) mesophases. In contrast to the common smectic mesophases of most dendritic LC polymers, nematic LC phases were observed. The complexation of PEI and the mesogen units is due to electrostatic interaction between the carboxylate groups and the ammonium end groups of PEI. LC properties were investigated by a combination of differential scanning calorimetry, polarizing light optical microscopy, and X‐ray diffractometry.

Schematic illustration of the supramolecular assembly of CBPA with PEIMe backbone.