Ultrasound stimuli on viscometric change of aqueous copolymers having acrylic acid and N-isopropyl acrylamide for thermo-sensitive segments

Ultrasound (US) was used to change the shear viscosity of an aqueous solution of copolymers having acrylic acid (AA) and N-isopropylacrylamide (NIPAM) segments. The US effect on the shear viscosity of the copolymers containing 10, 50 and 90 mol% of the NIPAM group having thermo-responsible property was examined when the US was exposed to the aqueous solution at different temperatures. The shear viscosity of the solution had a significant change at about 30-35°C when the viscosity was measured in the range of 0-60°C. While, the viscosity decreased with the increase of the temperature, the US operated at 28, 45 and 100 kHz also induced significant reduction of the shear viscosity. Evidence of the US effect on the shear viscosity reduction was observed by measurement of FT-IR spectra of the copolymer solution when the US was exposed. It was noted that considerable change of the spectra at the 28 kHz US was observed relative to that of the 45 and 100 kHz US. The tendency of the change in the shear viscosity and IR spectra was almost similar. Furthermore, the shear viscosity and IR spectra changed gradually to recover its original value as the US was stopped. This was due to the breaking and reformation of the hydrogen bonding between NIPAM and AA segments when the US was exposed and stopped, respectively.     

Molecular dynamics simulation of iron nanoparticle sintering during flame synthesis

The sintering process of iron nanoparticles produced in a flame environment is investigated by molecular dynamic (MD) simulations. The thermodynamic characteristics and restructuring pathways are studied for two-body and three-body sintering processes. The melting point, energy, and structures are computed for nanoparticles before and after sintering. A simplified model is proposed to predict the equilibrium temperature of nanoparticles upon sintering. The MD results are used to explain the formation mechanisms of two size ranges of nanoparticles during the flame synthesis. The role of sintering during nanoparticle growth is analyzed.     

Synthesis and structure of 5,7-diisopropyl-2-(quinolin-2-yl)-1,3-tropolone derivatives

Russian Chemical Bulletin - A synthetic procedure towards 4,6-diisopropyl-3-nitro-1,2-benzoquinone was elaborated. Based on this benzoquinone, a series of novel...     

Synthesis and reactivity of naphthalene sandwich complexes of molybdenum. X-ray structure of [Mo(η6-naphthalene) {P(OMe)3}3] and [Mo(H)(η6-naphthalene){P(OMe)3}3][BF4]

The sandwich complexes bis(η⁶-naphthalene)molybdenum(0) ( 1 ), bis(η⁶-1-methylnaphthalene)molybdenum(0) ( 2 ), and bis(η⁶-1,4-dimethylnaphthalene)molybdenum(0) ( 3 ) are synthesized by cocondensation of Mo-atoms with the naphthalene ligands. Complexes 1–3 are also obtained by reduction of MoCl₅ or MoCl₄. 2THF with highly activated Mg in the presence of the naphthalene ligands. Mg was activated by sublimation of the metal in a simple rotating solution reactor. Complex 2 exists as a mixture of regio- and stereoisomers. Three regioisomers, 3a–c , are formed in reactions of Mo-atoms with 1,4-dimethylnaphthalene, whereas 3a , the isomer with the Mo-atom coordinated to the unsubstituted rings, is formed selectively via the reductive method. The ligands in 1–3 are highly labile. CO displaces both naphthalene rings in 2 and 3 to give [Mo(CO)₆], while PF₃, P(OMe)₃, and PMe₃ displace only one coordinated naphthalene in 1 to yield the [Mo(η⁶-naphthalene)L₃] complexes 4–6 . In toluene, arene exchange is a competitive process in reactions of 1 with PF₃. Complexes 5 (L = P(OMe)₃) and 6 (L = PMe₃) react with HBF₄ to give the cationic metal hydride complexes 8 and 9 . The X-ray crystal structures of [Mo(η⁶-naphthalene) {P(OMe)₃}₃] ( 5 ) and [Mo(H)(η⁶-naphthalene) {P(OMe)₃}₃][BF₄] ( 8 ) are reported.     

Versions of Ekeland’s variational principle involving set perturbations

We consider Ekeland’s variational principle for multivalued maps. Instead of dealing with directional perturbations in a direction of the positive cone of the image space, we perturb the map under question by a convex subset of the positive cone to get stronger and more general versions. Many example are provided to highlight relations of our results to existing ones, including their advantages.     

Quantum teleportation of an arbitrary two-mode coherent state using only linear optics elements

We propose a linear optics scheme to teleport an arbitrary two-mode coherent state. The devices used are beam-splitters, phase-shifters and ideal photo-detectors capable of distinguishing between even and odd photon numbers. The scheme achieves faithful teleportation with a probability of 1/4. However, with additional use of an appropriate displacement operator, the teleported state can always be made near-faithful.     

Fe2O3/Mn2O3 nanoparticles: Preparations and applications in the photocatalytic degradation of phenol and parathion in water

In this study, nanoparticles of Fe₂O₃/Mn₂O₃ mixture were obtained using the sol–gel method. The synthesis uses the combination of polyvinyl alcohol (PVA) and tartaric acid (TA). Synthesized catalysts prove superior compared to those afforded from previous reports. To be specific, desired catalysts can be received at lower calcination temperature. Furthermore, their structures display higher uniformity in term of particle sizes. Finally, they show better performance for the photocatalytic degradation of model-persistent organic compounds.