Synthesis of New Mono- and Bis- Photochromic Compounds Based on Isatins

Among various photochromic compounds, 1,3-diazabicyclo[3.1.0]hex-3-ene derivatives are the subject of intense research due to their photochromic behavior even in the crystalline state, although molecules which show photochromic reactivity in the crystalline state are rare. In this research synthesis of several mono- and bis-1,3-diazabicyclo[3.1.0]hex-3-enes with isatin linkage are enclosed. All synthesized compounds undergo reversible photochromic reactions not only in the solution but also in crystalline state by irradiation with UV light (254 nm). Keywords: Photochromic, Isatin, Bis-1,3-diazabicyclo[3.1.0]hex-3-en

Synthesis of biscoumarin derivatives by the reaction of aldehydes and 4-hydroxycoumarin using ruthenium (III) chloride hydrate as a versatile homogeneous catalyst

The one-pot domino Knoevenagel-type condensation/Michael reaction of aromatic, heteroaromatic and aliphatic aldehydes with 4-hydroxycoumarin in aqueous media in the presence of ruthenium salt as homogeneous catalyst was investigated. It was found that 5 mol% of RuCl3.nH2O catalyzes biscoumarin synthesis in high yields (70-95%) under optimised, mild, green and environmentally benign reaction conditions in short times (25-35min)

Transport Properties in Ferromagnetic Josephson Junction between Triplet Superconductors

Charge and spin Josephson currents in a ballistic superconductor-ferromagnet-superconductor junction with spin-triplet pairing symmetry are studied using the quasiclassical Eilenberger equation. The gap vector of superconductors has an arbitrary relative angle with respect to magnetization of the ferromagnetic layer. We clarify the effects of the thickness of ferromagnetic layer and magnitude of the magnetization on the Josephson charge and spin currents. We find that 0-\pi transition can occur except for the case that the exchange field and d-vector are in nearly perpendicular configuration. We also show how spin current flows due to misorientation between the exchange field and d-vector.Comment: 6 pages, 8 figure

Stationary Josephson effect in a weak-link between nonunitary triplet superconductors

A stationary Josephson effect in a weak-link between misorientated nonunitary triplet superconductors is investigated theoretically. The non-self-consistent quasiclassical Eilenberger equation for this system has been solved analytically. As an application of this analytical calculation, the current-phase diagrams are plotted for the junction between two nonunitary bipolar $f-$wave superconducting banks. A spontaneous current parallel to the interface between superconductors has been observed. Also, the effect of misorientation between crystals on the Josephson and spontaneous currents is studied. Such experimental investigations of the current-phase diagrams can be used to test the pairing symmetry in the above-mentioned superconductors.Comment: 6 pages and 6 figure

Federated learning for performance prediction in multi-operator environments

Telecom vendors and operators deliver services with strict requirements on performance, over complex and sometimes partly shared network infrastructures. A key enabler for network and service management in such environments is knowledge sharing, and the use of data-driven models for performance prediction, forecasting, and troubleshooting. In this paper, we outline a multi-operator service metrics prediction framework using federated learning that allows privacy-preserved knowledge-sharing across operators for improved model performance, and also reduced requirements on data transfer within an operator network. Federated learning is compared against local and central learning strategies for multi-operator performance prediction, and it is shown to balance the requirements on data privacy, model performance, and the network overhead. Further, the paper provides insights on how data heterogeneity affects model performance, where the conclusion is that standard federated learning has certain robustness to data heterogeneity. Finally, we discuss the challenges related to training a federated learning model with a limited budget on the communication rounds. The evaluation is performed using a set of realistic publicly available data traces, that are adapted specifically for the purpose of studying multi-operator service performance prediction

Josephson effect in point contacts between ''f-wave'' superconductors

A stationary Josephson effect in point contacts between triplet superconductors is analyzed theoretically for most probable models of the order parameter in UPt_{3} and Sr_{2}RuO_{4}. The consequence of misorientation of crystals in superconducting banks on this effect is considered. We show that different models for the order parameter lead to quite different current-phase dependences. For certain angles of misorientation a boundary between superconductors can generate the parallel to surface spontaneous current. In a number of cases the state with a zero Josephson current and minimum of the free energy corresponds to a spontaneous phase difference. This phase difference depends on the misorientation angle and may possess any value. We conclude that experimental investigations of the current-phase dependences of small junctions can be used for determination of the order parameter symmetry in the mentioned above superconductors.Comment: 11 pages, 8 figure

“On Water” Sonochemical Multicomponent Synthesis of Novel Bioactive 1,1′-(Aryl)bis(2-(cyclohexylamino)-2-oxoethane-1,1-diyl) Di(alkanoates and benzoates)

An expeditious, efficient, and ecofriendly ultrasound-promoted synthesis of a series of novel 1,1′-(aryl)bis(2-(cyclohexylamino)-2-oxoethane-1,1-diyl) di(alkanoate and benzoate) derivatives (6a–k), as useful building block candidates for natural products and drugs, is reported. The target compounds were prepared by the reaction of alkyl or aryl carboxylic acid, various bisaldehydes and isocyanocyclohexane in water using one-pot isocyanide-based multicomponent approach. This efficient protocol without using any catalyst furnished the products in short reaction times (4-5 min) and excellent yields (87–96%). The antibacterial activity of the selected products was also examined. Some products showed promising activities

Self-similar disk packings as model spatial scale-free networks

The network of contacts in space-filling disk packings, such as the Apollonian packing, are examined. These networks provide an interesting example of spatial scale-free networks, where the topology reflects the broad distribution of disk areas. A wide variety of topological and spatial properties of these systems are characterized. Their potential as models for networks of connected minima on energy landscapes is discussed.Comment: 13 pages, 12 figures; some bugs fixed and further discussion of higher-dimensional packing

Dispersion of carbon nanotubes in polyamide 6 for microinjection moulding

The focus of this study was to investigate the dispersion state of pure and functionalized carbon nanotubes in polyamide 6, on composites prepared by twin-screw extrusion and then processed by microinjection moulding. Nanocomposites were prepared with different carbonvnanotube compositions, with and without functionalization. The nanotubes were functionalized by the 1,3-dipolar cycloaddition reaction. The dispersion of the carbon nanotube agglomerates was quantified using optical microscopy and image analysis. The effect of functionalization on the polyamide 6/carbon nanotube interface, the nanocomposite morphology and the mechanical and electrical properties were studied. It was observed that the microinjected composites with functionalized carbon nanotubes presented improved dispersion, with smaller carbon nanotube agglomerate area ratio compared to the composites with pure nanotubes. The functionalized nanotubes showed better adhesion to polyamide 6 compared to pure nanotubes, as observed by scanning electron microscopy. The incorporation of carbon nanotubes considerably improved the mechanical properties. The effect of high polymer shear rate on carbon nanotube alignment during microinjection moulding was assessed by comparing the electrical resistivity of the composite after extrusion and after microinjection moulding, through the thickness and along the flow direction. The experiments showed that the mould design and processing conditions significantly affected electrical resistivity.Fundação para a Ciência e Tecnologia (project PEst-C/CTM/LA0025/2013