Finite Nilpotent BRST Transformations in Hamiltonian Formulation

We consider the finite field dependent BRST (FFBRST) transformations in the context of Hamiltonian formulation using Batalin-Fradkin-Vilkovisky method. The non-trivial Jacobian of such transformations is calculated in extended phase space. The contribution from Jacobian can be written as exponential of some local functional of fields which can be added to the effective Hamiltonian of the system. Thus, FFBRST in Hamiltonian formulation with extended phase space also connects different effective theories. We establish this result with the help of two explicit examples. We also show that the FFBRST transformations is similar to the canonical transformations in the sector of Lagrange multiplier and its corresponding momenta.     

Effect of processing routes on microstructure, electrical and dielectric behavior of Mg-doped CaCu3Ti4O12 electro-ceramic

In the present communication, data on magnesium-doped calcium copper titanate CaCu_2.90Mg_0.10Ti₄O₁₂ (CCMTO) electro-ceramic, synthesized by the semi-wet route (SWR), ball-milled route (BMR) and solid-state route (SSR), is characterized by TG-DTA, XRD, SEM, EDX and TEM techniques. XRD confirmed the formation of single phase in CCMTO ceramic. The CuO phase present at grain boundaries in SWR ceramic was shown by the SEM micrograph, which was verified by EDX. The TEM image of SWR ceramic shows nanocrystalline particles in the range 80±20 nm. The value of the dielectric constant of SWR (ε _r ～20091) ceramic is higher than those of BMR and SSR (ε _r ～1247) ceramics at 1 kHz at 450 K. A dielectric relaxation has been observed in the frequency range 100 Hz–100 kHz. The high-temperature dielectric dispersion shows one large low-frequency response and two Debye-type relaxations. The impedance and modulus studies show the highest grain-boundary resistance for BMR ceramic.     

Nickel(II)-induced excimer formation of a naphthalene-based fluorescent probe for living cell imaging

Ni(2+)-induced intramolecular excimer formation of a naphthalene-based novel fluorescent probe, 1-[(naphthalen-3-yl)methylthio]-2-[(naphthalen-6-yl)methylthio]ethane (L), has been investigated for the first time and nicely demonstrated by excitation spectra, a fluorescence lifetime experiment, and (1)H NMR titration. The addition of Ni(2+) to a solution of L (DMSO:water = 1:1, v/v; λ(em) = 345 nm, λ(ex) = 280 nm) quenched its monomer emission, with subsequent enhancement of the excimer intensity (at 430 nm) with an isoemissive point at 381 nm. The fluorescence lifetime of free L (0.3912 ns) is much lower than that of the nickel(2+) complex (1.1329 ns). L could detect Ni(2+) as low as 1 × 10(-6) M with a fairly strong binding constant, 2.0 × 10(4) M(-1). Ni(2+)-contaminated living cells of plant origin could be imaged using a fluorescence microscope.     

Syntheses, Structures, and Steady State and Time Resolved Photophysical Properties of a Tetraiminodiphenol Macrocyclic Ligand and Its Dinuclear Zinc(II)/Cadmium(II) Complexes with Coordinating and Noncoordinating Anions

The work in the present investigation reports the syntheses, structures, steady state, and time-resolved photophysical properties of a tetraiminodiphenol macrocyclic ligand H(2)L and its eight dinuclear zinc(II) complexes and one cadmium(II) complex having composition [Zn(2)L(H(2)O)(2)](ClO(4))(2)·2CH(3)CN (1), [Zn(2)L(H(2)O)(2)](ClO(4))(2)·2dmf (2), [Zn(2)L(H(2)O)(2)](NO(3))(2)·2dmf (3), [Zn(2)LCl(2)] (4), [Zn(2)L(N(3))(2)] (5), [Zn(2)L(NCS)(2)] (6), [Zn(2)L(NCO)(2)] (7), [Zn(2)L(NCSe)(2)](2)·dmf (8), and [Cd(2)L(OAc)(2)] (9) with various coordinating and noncoordinating anions. The structures of all the complexes 1-9 have been determined by single-crystal X-ray diffraction. The noncovalent interactions in the complexes result in the generation of the following topologies: two-dimensional network in 1, 2, 4, 6, 7, 8, and 9; three-dimensional network in 5. Spectrophotometric and spectrofluorometric titrations of the diprotonated salt [H(4)L](ClO(4))(2) with triethylamine as well as with zinc(II) acetate and cadmium(II) acetate have been carried out, revealing fluorescence enhancement of the macrocyclic system by the base and the metal ions. Steady state fluorescence properties of [H(4)L](ClO(4))(2) and 1-9 have been studied and their quantum yields have been determined. Time resolved fluorescence behavior of [H(4)L](ClO(4))(2) and the dizinc(II) and dicadmium(II) complexes 1-9 have also been studied, and their lifetimes and radiative and nonradiative rate constants have been determined. The induced fluorescence enhancement of the macrocycle by zinc(II) and cadmium(II) is in line with the greater rate of increase of the radiative rate constants in comparison to the smaller rate of increase of nonradiative rate constants for the metal complexes. The fluorescence decay profiles of all the systems, being investigated here, that is, [H(4)L](ClO(4))(2) and 1-9, follow triexponential patterns, revealing that at least three conformers/components are responsible to exhibit the fluorescence decay behavior. The systems and studies in this report have been compared with those in the reports of the previously published similar systems, revealing some interesting aspects.     

Evidence of oscillatory convection inside an evaporating multicomponent droplet in a closed chamber

Visualization of an evaporating binary (ethanol-water) droplet reveals presence of oscillatory internal circulation. The visualization is done by using a laser scattering technique. The oscillatory circulation possibly results from the opposing effect of solutal and thermal Marangoni convection as proposed in some earlier theoretical works. The frequency of this oscillation is measured and the variation of this frequency with the initial concentration of the volatile component (ethanol) is reported.     

Ionic liquid mediated 1,3-dipolar cycloaddition of azomethine ylides: a facile and green synthesis of novel dispiro heterocycles

A greener, facile and efficient one-pot, three-component procedure for the synthesis of novel dispiropyrrolidine-bisoxindole derivatives by cycloaddition trapping of azomethine ylides generated in situ, via decarboxylative condensation of isatin with sarcosine (α-amino acid), has been reported in [bmim]PF₆, an ionic liquid as a recyclable solvent in excellent yield without using any catalyst. This protocol provides mild reaction conditions, high yields of product in short reaction time, high regio- and stereoselectivity, operational simplicity and environmentally benign procedure.     

Photoinduced electron transfer between various coumarin analogues and N,N-dimethylaniline inside niosome, a nonionic innocuous polyethylene glycol-based surfactant assembly

Photoinduced electron transfer (ET) reactions between coumarin dyes and N,N-dimethylaniline have been investigated inside niosome, a nonionic innocuous polyethylene glycol (PEG)-based surfactant assembly using steady state and time-resolved fluorescence measurements. The location of coumarin dyes inside the bilayer headgroup region of niosome has been reported and it was verified by determination of the high distribution coefficient of all the dyes inside niosome compared to bulk water. Fluorescence anisotropy parameters of the dyes inside niosome are also in good correlation with the above inference about their location. Bimolecular diffusion guided rates inside niosome were determined by comparing the microviscosities inside niosome and in acetonitrile and butanol solutions and it was found that diffusion of the donor and the acceptor is much slower than the ET rates, implying insignificant role of reactant diffusion in ET reaction inside niosome. We have observed a Marcus inversion region in our restricted media, which shows maxima at lower exergonicity. Such behavior has been demonstrated by the presence of nonequilibrium solvent excited state using two dimensional ET (2DET) theory. Unusually high quenching rates of two coumarins C-152 and C-152A inside niosome were explained by the presence of a stable non-fluorescent twisted intramolecular charge transfer (TICT) state along with an emissive intramolecular charge transfer (ICT) state. Moreover, intermolecular hydrogen bonding between carbonyl oxygens of these two dyes and water in their non-emissive and emissive charge transfer states also plays a key role in their dynamical exchange with each other [G.-J. Zhao and K.-L. Han, Acc. Chem. Res., 2011].     

Recognition of Hg2+ ion through restricted imine isomerization: crystallographic evidence and imaging in live cells

A newly synthesized imine-based receptor (L) showed remarkable specificity toward the Hg(2+) ion in aqueous media over other metal ions. Coordination of L to Hg(2+) induces a turn-on fluorescence response. This was explained based on the restricted imine isomerization along with PET on coordination to Hg(2+). X-ray structural evidence tends to favor a C-C bond rotation rather than C═N isomerization for adopting a favorable conformation in L for coordination to Hg(2+). This reagent could be used for imaging the accumulation of Hg(2+) ions in HeLa cells.