A microscopic model for noise induced transport: Heat-bath nonlinearly driven by external white noise

This work explores the observation that, even in the absence of a net externally applied bias, a symmetric homogeneous system coupled linearly to two heat baths is capable of producing unidirectional motion simply by nonlinearly driving one of the heat baths by an external Gaussian white noise. This is quite contrary to the traditional observation that, in order to obtain a net drift current, a state-dependent dissipation, which is a consequence of nonlinear system-bath coupling, is ubiquitous.     

Efficient band-pass and stop-band filtering by GaAs–Al c Ga1− c As generalized Thue–Morse multibarrier systems

The influence of Al concentration and barrier width on the transmission spectra in GaAs–Al _c Ga_{1? c} As heterostructure is studied for two different kinds of the generalized Thue–Morse multibarrier systems (GTMS). These structures provide interesting filter properties with regard to effective band-pass or stop-band (of extremely low width) circuitry. The first kind of GTMS is suitable for application as a band-pass electronic filter, while the second kind as stop-band filter. High Al concentration and large barrier width result in sharp resonances in the transmission spectrum.     

Densely ball remotal subspaces of C(K)

We call a subspace Y of a Banach space X a DBR subspace if its unit ball By admits farthest points from a dense set of points of X. In this paper, we study DBR subspaces of C(K). In the process, we study boundaries, in particular, the Choquet boundary of any general subspace of C(K). An infinite compact Hausdorff space K has no isolated point if and only if any finite co-dimensional subspace, in particular, any hyperplane is DBR in C(K). As a consequence, we show that a Banach space X is reflexive if and only if X is a DBR subspace of any superspace. As applications, we prove that any M-ideal or any closed *-subalgebra of C(K) is a DBR subspace of C(K). It follows that C(K) is ball remotal in C(K)^**.     

Facile Access to Optically Active 2,6‐Dialkyl‐1,5‐Diazacyclooctanes

The chiral substituted 1,5‐diazacyclooctane (1,5‐DACO) is of considerable importance and has attracted attention from a wide range of fields due to their unique chemical and biological properties. Despite the application potential, further study has not been optimized due to difficulties in their synthetic accessibility. Here, we report that the 1,5‐DACO bearing a chiral auxiliary obtained from the formal [4+4] cycloaddition of N‐alkyl‐α,β‐unsaturated imines can be further derivatized by nucleophilic alkylation to give various chiral substituted 1,5‐DACO derivatives. The removal of the chiral auxiliary was effectively carried out using hydrogenation over Pearlman's catalyst. This methodology allows the production of a broad range of unprecedented optically active 2,6‐dialkyl‐1,5‐DACO, which could not be accessed by other methods.     

Binding energy of triton and scattering lengths in neutron-deuteron collision in Faddeev formalism with local potential

A separable representation for the off-shell two-body t-matrix for a local Hulthén potential is presented, in which deuteron states are chosen as the expansion bases. Using the Faddeev equations with these t-matrices as input, the ground state energy of the triton and doublet and quartet scattering lengths in neutron-deuteron scattering, have been computed. The results have been compared with the experimental findings and the theoretical results of Sitenko et al. obtained in the Sturmian function representation with the same Hulthén potential.     

A tetraphenylmethane based dendritic tolan-anthracene dyad: synthesis and energy transfer properties

In order to synthesize a peripherally rigid dendritic donor-acceptor dyad for energy transfer studies, a tritolan dendron based on a tetraphenylmethane scaffold was prepared from New Fuchsin. The dendron showed a small degree of homoconjugation but a large hypochromic effect. Coupling of two such dendrons with an anthracene core led to a dendritic tolan-anthracene dyad whose steady state photophysical studies (UV, PL, PLE) showed vectorial transfer of excitation energy from the surface tolan units to the anthracene core.     

Fluorescence resonance energy transfer from TX-100 to 3-acetyl-4-oxo-6,7-dihydro-12H-indolo-[2,3-a]quinolizine in premicellar and micellar environments

Fluorescence (Förster) resonance energy transfer (FRET) from the phenyl groups of the non-ionic triton X-100 (TX-100) micelles to a potent bioactive molecule 3-acetyl-4-oxo-6,7-dihydro-12H-indolo-[2,3-a] quinolizine (AODIQ) has been studied using steady state absorption and fluorescence techniques. High values of Stern–Volmer constants (K_SV) suggest that a long-range dipole–dipole interaction is operative for the energy transfer mechanism. From the analysis of the quenching of the donor fluorescence the energy transfer efficiency (E) has been determined in both premicellar and micellar environments. Experimental results reveal that the energy transfer process is more efficient in the micellar environment compared to the premicellar situation.     

Some contribution to W(VI)-peroxo-chemistry: Synthesis,spectroscopic characterization,reactivity and DFT studies

Synthesis of white microcrystalline oxodiperoxotungstate(VI) complexes, K[WO(O₂)₂(L)(H₂O)]·H₂O, (L ?= ?salicylate, 5-chlorosalicylate, 4-hydroxybenzoate) have been achieved from reaction of Na₂WO₄·2H₂O with 30% H₂O₂ and the respective hetero-ligands at pH Ca. 7–7.5 in aqueous medium. The newly synthesized compounds were comprehensively characterized by elemental analyses, spectral studies, room temperature magnetic moment measurements and mass spectrometric studies. Infrared spectra suggest that, peroxo groups are bonded to the WO⁺⁴ center in a triangular bidentate (C_2v) fashion and the hetero-ligands benzene-core hydroxycarboxylic acids viz. salicylic acid, 5-chlorosalicylic acid, 4-hydroxybenzoic acid in anoinic form are coordinated in monodentate manner. Compounds are fairly stable in aqueous solution for sufficient period of time. The results of mass spectrometric analysis lend support to the molecular composition of the complexes ascertained on the basis of elemental analyses and spectroscopic studies. Compound potassium(aquo)(5-chlorosalicylato)oxodiperoxotungstate(VI)monohydrate, K[WO(O₂)₂(5-chlorosalicylate)(H₂O)]·H₂O, act as an oxidant of bromide ion in aqueous phase bromination of chosen organic substrates to their corresponding bromo organics. Density Functional Theory (TD-DFT) calculations were performed on the synthesized complexes substantiated the experimentally obtained results. The TD-DFT optimized structures are in excellent agreement with the results of elemental analyses, spectral as well as mass spectrometric data.     

Surfactant chain-length-dependent modulation of the prototropic transformation of a biological photosensitizer: norharmane in anionic micelles

A photophysical study of norharmane (NHM), an efficient cancer cell photosensitizer, has been undertaken in well-characterized biomimetic micellar nanocavities formed by anionic surfactants of varying chain length, namely, sodium decyl sulfate (S10S), sodium dodecyl sulfate (S12S), and sodium tetradecyl sulfate (S14S), using steady-state and time-resolved fluorescence spectroscopy. The effect of the hydrophobic chain length on the structural dynamism of the fluorophore has been reported. Experimental results demonstrate that the equilibrium of this dynamism is sensitive to the environment. Variation in the surfactant chain length plays an important role in promoting a specific prototropic form of the probe molecule. A striking feature of the present study is that an increase in the surfactant chain length (hydrophobicity) favors the cationic species of NHM. This has been rationalized on the basis of changes in the local pH and the aggregation number of the micelles. A fluorescence quenching study of the micelle-bound probe using ionic quencher Cu2+ corroborates this.