Phonon Dispersion in Polypyrrole

A study of the normal modes of vibration and their dispersion in polypyrrole (PPY) based on the Urey-Bradley force field is reported. It gives a fuller interpretation of previously reported FTIR spectra. Characterstic features of dispersion curves, such as regions of high density-of-states, repulsion, and character mixing of dispersive modes, are discussed. Predictive values of heat capacity as a function of temperature are reported.     

Effect of the functionalization of the axial phthalocyanine ligands on the energy transfer in QD-based donor-acceptor pairs.

This study examines the electronic coupling between quantum dots (QDs) and molecules on their surfaces as a function of the modality of their interaction. As a probe, the energy transfer (ET) between CdSe QDs and phthalocyanines (Pcs) was monitored and evaluated with regard to the functionalization of the axial phthalocyanine ligand, bulkiness of the functional group bridging the QD donor and Pc acceptor, and the number of the functionalized axial ligands. New silicon PCs and their conjugates with CdSe QDs were synthesized. The ET efficiency and kinetics were studied by steady state and femtosecond time-resolved absorption spectroscopy. We observed a decrease in ET efficiency with the increase in functional group bulkiness, which could be explained by increasing steric hindrance between the ET pair. In addition, a higher ET efficiency was observed for amino and thiol functionalized Pcs compared to Pcs without functional group on the axial alkyl chain.     

Navigation of underwater robot based on dynamically adaptive harmony search algorithm

The current research work has employed an evolutionary based novel navigational strategy to trace the collision free near optimal path for underwater robot in a three-dimensional scenario. The population based harmony search algorithm has been dynamically adapted and used to search next global best pose for underwater robot while obstacle is identified near about robot’s current pose. Each pose is evaluated based on their respective value for objective function which incorporates features of path length minimization as well as obstacle avoidance. Dynamic adaptation of control parameters and new perturbation schemes for solution vectors of harmony search has been proposed to strengthen both exploitation and randomization ability of present search process in a balanced manner. Such adaptive tuning process has found to be more effective for avoiding early convergence during underwater motion in comparison with performances of other popular variants of Harmony Search. The proposed path planning method has also shown better navigational performance in comparison with improved version of ant colony optimization and heuristic potential field method for avoiding static obstacles of different shape and sizes during underwater motion. Simulation studies and corresponding experimental verification for three-dimensional navigation are performed to check the accuracy, robustness and efficiency of proposed dynamically adaptive harmony search algorithm.     

Poly-β-hydroxybutyrate Production by Fast-Growing Rhizobia Cultivated in Sludge and in Industrial Wastewater

In our study, the potential of producing polyhydroxybutyrate (PHB) by cultivating fast-growing rhizobia (Sinorhizobium meliloti, Rhizobium leguminosarum bv. viciae, R. leguminosarum bv. phaseoli and R. leguminosarum bv. trifolii) in sludge and in industrial wastewater was evaluated. Results confirmed the possibility of using sludge as media for rhizobial growth. During growth, substantial quantity of PHB was accumulated and yields varied depending on the media and rhizobial species. Growing in sludge, PHB production did not exceed 3.7% w/w for all strains at the end of experiment (after 72 h). During the growth of S. meliloti, PHB yield varied and the maximum value reached 7.27% w/w after 60 h, with 1% Total Suspend Solid (TSS) sludge. Alkaline sludge pre-treatment affects rhizobial growth but did not improve the PHB accumulation. While growing S. meliloti in industrial wastewater, the PHB yields varied and the highest value was obtained with slaughterhouse wastewater (10.7% w/w) after 35 h of growth. Therefore, this work shows the potential of exploiting PHB production by rhizobia growing in wastewater or sludge which could be applied to bioplastic industry, and confirms the potential of these recyclable wastes for high production of rhizobial cells useable for legumes inoculants production. This study provides an environmentally sound way of sludge and wastewater management and use in diverse biotechnological applications.     

Observation of non-Förster-type energy-transfer behavior in quantum dot-phthalocyanine conjugates

The effect of linker chain length on the energy transfer from CdSe quantum dots (QDs) to silicon phthalocyanine (Pc) photodynamic therapy agents was investigated by steady-state and femtosecond time-resolved spectroscopy with 500 nm light for the specific excitation of the QD energy donor. The conjugation between the QD and the Pc was achieved with linker chains varying from 4 to 9 bond lengths by incorporating 1-6 methylene groups into the axial ligand of the Pc. With increasing chain length, the energy-transfer efficiency increased, which appears to be opposed to a purely F?rster-type resonance energy-transfer behavior that is commonly discussed for the energy transfer in QD conjugates. The obtained results provide strong evidence for a capping-layer-mediated energy transfer in the QD-based donor-acceptor conjugates.     

One-pot thioetherification of aryl halides with thiourea and benzyl bromide in water catalyzed by Cu-grafted furfural imine-functionalized mesoporous SBA-15

Surface functionalization of SBA-15 followed by its reaction with Cu(OAc)(2) has been carried out to develop a new Cu-grafted functionalized mesoporous material, which catalyzes one-pot three component coupling of different aryl halides with thiourea and benzyl bromide in aqueous medium to produce aryl thioethers in very good yields (80-88%).     

A two-body continuous-discrete filter

In the theory of classical mechanics, the two-body central forcing problem is formulated as a system of the coupled nonlinear second-order deterministic differential equations. The uncertainty introduced by the small, unmodeled stochastic acceleration is not assumed in the particle dynamics. The small, unmodeled stochastic acceleration produces an additional random force on a particle. Estimation algorithms for a two-body dynamics, without introducing the stochastic perturbation, may cause inaccurate estimation of a particle trajectory. Specifically, this paper examines the effect of the stochastic acceleration on the motion of the orbiting particle, and subsequently, the stochastic estimation algorithm is developed by deriving the evolutions of conditional means and conditional variances for estimating the states of the particle-earth system. The theory of the nonlinear filter of this paper is developed using the Kolmogorov forward equation “between the observations" and a functional difference equation for the conditional probability density “at the observation." The effectiveness of the nonlinear filter is examined on the basis of its ability to preserve perturbation effect felt by the orbiting particle and the signal-to-noise ratio. The Kolmogorov forward equation, however, is not appropriate for the numerical simulations, since it is the equation for the evolution of “the conditional probability density." Instead of the Kolmogorov equation, one derives the evolutions for the moments of the state vector, which in our case consists of positions and velocities of the orbiting body. Even these equations are not appropriate for the numerical implementations, since they are not closed in the sense that computing the evolution of a given moment involves the knowledge of higher order moments. Hence, we consider the approximations to these moment evolution equations. This paper makes a connection between classical mechanics, statistical mechanics and the theory of the nonlinear stochastic filtering. The results of this paper will be of use to astrophysicists, engineers and applied mathematicians, who are interested in applications of the nonlinear filtering theory to the problems of celestial and satellite mechanics. Simulation results are introduced to demonstrate the usefulness of an analytic theory developed, in this paper.     

Spectrophotometric determination of trace level thorium with n-phenylbenzohydroxamic acid

A method for the determination of thorium(IV) based on thorium-PBHA complex, which is extracted into amyl alcohol, is described. The thorium is back-extracted from amyl alcohol with 0.2M hydrochloric acid and estimated spectrophotometrically with thorin. The system has a maximum absorbance at 545 nm and obeys Beer's law between 0.5 to 12.5 ppm and the molar absorption coefficients is 1.7·10 1·mol^?1·cm^?1., Various parameters for the extraction and back-extraction and the effect of diverse ions have been studied.