Cut points in some connected topological spaces

We prove that a connected topological space with endpoints has exactly two non-cut points and every cut point is a strong cut point; it follows that such a space is a COTS and the only two non-cut points turn out to be endpoints (in each of the two orders) of the COTS. A non-indiscrete connected topological space with exactly two non-cut points and having only finitely many closed points is proved homeomorphic to a finite subspace of the Khalimsky line. Further, it is shown, without assuming any separation axiom, that in a connected and locally connected topological space X, for a, b in X, S[a,b] is compact whenever it is closed. Using this result we show that an H(i) connected and locally connected topological space with exactly two non-cut points is a compact COTS with end points.     

Topological Dyons

Using a two potential approach, dyon solutions have been found in the temporal and non-temporal gauges for a non-Abelian theory. Both the charges, electric and magnetic, of the temporal dyon solution are topological, while for the non-temporal case both charges are partially topological.     

TDDFT Investigation of the Electronic Structures and Photophysical Properties of Fluorescent Extended Styryl Push-Pull Chromophores Containing Carbazole Unit

Push-pull chromophores attached to carbazole based π-conjugating spacers bearing N-alkylamino donors, cyanovinyl and carbethoxy acceptors have been studied by the means of UV-Visible measurements. The intramolecular charge transfer (ICT) of these π-conjugated systems has also been tested by investigating the ability of the solute molecules to undergo shifts in their fluorescence emission maxima with increasing solvent polarity. Density Functional Theory [B3LYP/6-31G(d)] and Time Dependent Density Functional Theory [TD-B3LYP/6-31G(d)] computations have been used to have more understanding of the structural, molecular, electronic and photophysical parameters of push-pull dyes. The largest wavelength difference between the experimental and computed electronic absorption maxima was 45 nm. For emission, a largest difference of 61 nm was observed. The ground state and excited state dipole moments in different solvents were determined using experimental solvatochromic data and computed Onsager radii. The dipole moments of the molecules in the excited state were observed to be higher than in the ground state.     

Synthesis, Photo-physical and DFT Studies of ESIPT Inspired Novel 2-(2′,4′-Dihydroxyphenyl) Benzimidazole, Benzoxazole and Benzothiazole

Novel ESIPT inspired benzimidazole, benzoxazole and benzothiazole were synthesized from 2,4-dihydroxy benzoic acid and 1,2-phenelenediamine, 2-aminophenol, and 2-aminothiophenol respectively. The synthesized 2-(2′,4′-dihydroxyphenyl) benzimidazole, benzoxazole and benzothiazole are fluorescent and the emission characteristic are very sensitive to the micro-environment. They show a single absorption and dual emission with large Stokes shift originating from excited state intramolecular proton transfer. The absorption-emission characteristics of all these compounds are studied as a function of pH. The change in the electronic transition, energy levels, and orbital diagrams of synthesized compounds were investigated by the molecular orbital calculation and were correlated with the experimental spectral emission. Experimental absorption and emission wavelengths are in good agreement with those predicted using the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT) [B3LYP/6-31G(d)].

Spin waves transport across a ferrimagnetically ordered nanojunction of cobalt-gadolinium alloy between cobalt leads

A model calculation is presented for the spin wave scattering and coherent transport at the ferrimagnetically ordered cobalt-gadolinium alloy nanojunction between cobalt leads. The structural model for the amorphous alloy nanojunction [Co_1/2Gd_1/2]₃ is considered as an ordered alloy hcp structure of three (0001) atomic planes between the leads. To analyze the spin dynamics and spin wave scattering at the nanojunction boundary, the phase field matching method (PFMT) is implemented over the ground state of the system, in the Heisenberg Hamiltonian representation. The coherent reflection and transmission probabilities of spin waves from the cobalt leads incident onto the nanojunction boundary are calculated, and numerical results are presented for the coherent SW transport across the nanojunction over the entire range of their frequencies. The results are especially valid in the interval between nanometric SW wavelengths greater than the nanojunction width and macroscopic wavelengths. They demonstrate in particular, the possibility of the resonance assisted maxima for the SW transmission spectra owing to the interactions between the incident spin waves and the localized spin resonances on the nanojunction. This effect is general and may be observed at different characteristic frequencies and corresponding incident angles.     

Intra‐laser‐cavity microparticle sensing with a dual‐wavelength distributed‐feedback laser

An integrated intra‐laser‐cavity microparticle sensor based on a dual‐wavelength distributed‐feedback channel waveguide laser in ytterbium‐doped amorphous aluminum oxide on a silicon substrate is demonstrated. Real‐time detection and accurate size measurement of single micro‐particles with diameters ranging between 1 µm and 20 µm are achieved, which represent the typical sizes of many fungal and bacterial pathogens as well as a large variety of human cells. A limit of detection of ∼500 nm is deduced. The sensing principle relies on measuring changes in the frequency difference between the two longitudinal laser modes as the evanescent field of the dual‐wavelength laser interacts with micro‐sized particles on the surface of the waveguide. Improvement in sensitivity far down to the nanometer range can be expected upon stabilizing the pump power, minimizing back reflections, and optimizing the grating geometry to increase the evanescent fraction of the guided modes.     

An efficient and highly diastereoselective synthesis of carbocyclic spiropyrazolones via one-pot sequential dual organo-silver catalyzed Michael-hydroalkylation reactions

An economical approach for the diastereoselective synthesis of highly functionalized carbocyclic spiropyrazolone derivatives having one quaternary and two tertiary stereocenters along with one exocyclic double bond exploiting dual organo-silver sequential catalysis has been developed. The unified method to both cyclohexyl and cyclopentyl spirocompounds involves the reaction of γ- and β-nitroalkynes with alkylidene pyrazolones catalyzed by Hünig’s base followed by carbophilic activation of the triple bond with a Ag(I) salt leading to cyclization via hydroalkylation.     

Hydrogen‐Bonding‐Regulated Supramolecular Nanostructures and Impact on Multivalent Binding

Herein we describe the H‐bonding‐regulated nanostructure, thermodynamics, and multivalent binding of two bolaamphiphiles NDI‐1 and NDI‐2 consisting of a hydrophobic naphthalene diimide connected to a hydrophilic wedge by a H‐bonding group and a glucose moiety on its two arms. NDI‐1 and NDI‐2 differ by the single H‐bonding group, namely, hydrazide or amide, which triggers the formation of vesicles and cylindrical micelles, respectively. Although the extended H‐bonding ensures stacking with head‐to‐head orientation and the formation of an array of the appended glucose moieties in both systems, the adaptive cylindrical structure exhibited superior multivalent binding with concanavalin A (ConA) to that of the vesicle. A control amphiphile lacking a H‐bonding group assembled with a random lateral orientation to produce spherical micelles without any notable multivalent binding.     

Synthesis,Electrochemical and Antimicrobial Studies of Me6-Dibenzotetraazamacrocyclic Complexes of Ni(II) and Cu(II) Metal Ions

Russian Journal of Electrochemistry - Me6-dibenzotetraaza[14] annulene type macrocyclic complexes of Ni(II) and Cu(II) have been synthesized by template method and characterized by employing...