Shape evolution in odd-A 137 Pm

The odd mass nucleus ¹³⁷Pm has been studied to high spins through the ¹⁰⁹Ag(³²S, 2p2n)¹³⁷Pm reaction at an incident beam energy of 150 MeV. The de-exciting ??-rays were detected using an array of 18 Compton suppressed clover detectors. The level scheme of ¹³⁷Pm has been extended up to $J^\pi = \tfrac{{43}} {2}^ -$ and excitation energy of E _x ? 6 MeV with the observation of 42 new gamma transitions. The linear polarization (IPDCO) measurements for the ??-ray transitions have been done for the first time. The spin and parity assignments for most of the reported levels have been made using these results and the coincidence angular anisotropy (R_DCO) measurements. The nuclear shape evolution is discussed in the light of Total Routhian Surface (TRS) and Cranked Shell Model (CSM) calculations.     

Silver-Gold Nanocomposite Substrates for Metal-Enhanced Fluorescence: Ensemble and Single-Molecule Spectroscopic Studies

In recent years, there has been a growing interest in the studies involving the interactions of fluorophores with plasmonic nanostructures or nanoparticles. These interactions lead to several favorable effects such as increase in the fluorescence intensities, increased photostabilities, and reduced excited-state lifetimes that can be exploited to improve the capabilities of present fluorescence methodologies. In this regard, we report the use of newly developed silver-gold nanocomposite (Ag-Au-NC) structures as substrates for metal-enhanced fluorescence (MEF). The Ag-Au-NC substrates have been prepared by a one-step galvanic replacement reaction from thin silver films coated on glass slides. This approach is simple and suitable for the fabrication of MEF substrates with large area. We have observed about 15-fold enhancement in the fluorescence intensity of ATTO655 from ensemble fluorescence measurements using these substrates. The fluorescence enhancement on the Ag-Au-NC substrates is also accompanied by a reduction in the fluorescence lifetime of ATTO655, which is consistent with the fluorophore-plasmon coupling mechanism. Single-molecule fluorescence measurements have been performed to gain more insight into the metal-fluorophore interactions and to unravel the heterogeneity in the interaction of individual fluorophores with the fabricated substrates. The single-molecule studies are in good agreement with the ensemble measurements and show maximum enhancements of ~50-fold for molecules located in proximity to the "hotspots" on the substrates. In essence, the Ag-Au-NC substrates have a very good potential for various MEF applications.     

Early detection of insulin fibrillation: a fluorescence lifetime assay to probe the pre-fibrillar regime

Using human insulin, we report for the first time, the evaluation of fluorescence lifetime of an extrinsically added fluorogenic dye, Thioflavin T (ThT), as a more sensitive and convenient method for the assessment of fibrillation in the pre-fibrillar regime.     

Extending photocatalytic activity of TiO2 nanoparticles to visible region of illumination by doping of cerium

Cerium-doped Titanium dioxide (TiO(2)) nanoparticles are prepared by sol-gel method. Doping shifts the UV absorption edge of TiO(2) to the visible region, making it efficient for visible light photocatalysis. Incorporation of cerium decreases the effective band gap of TiO(2) and increases the Urbach energy levels. At the dopant concentrations of 0.015 and 0.025 mol the luminescence intensity increases compared to undoped TiO(2); however, the luminescence is quenched at 0.035 mol. Quenching of luminescence indicates efficient separation of charge carriers. Undoped TiO(2) is showing poor performance in the photocatalytic degradation of methyl orange under visible light. However, on cerium doping its photoactivity is increased, and is drastically enhanced at 0.035 mol of cerium. Further increase in Ce(3+) doping level to 0.045 mol results in the reduction of the photodegradation of the dye. On UV irradiation, entire samples show good photocatalytic activity up to 30 min, but their efficiency decreases when irradiation time is increased to 45 min. Irradiation for longer time results in negative charging of the TiO(2) surface with migrating electrons. The negatively charged surface repels the OH(-) ion and O(2) molecule from adsorbing on its surface thus decreasing the availability of hydroxyl and superoxide radical for dye degradation.     

Organocatalytic asymmetric direct vinylogous Michael addition of α,β-unsaturated γ-butyrolactam to nitroolefins

The first organocatalytic enantioselective direct vinylogous Michael reaction of α,β-unsaturated γ-butyrolactam to nitroolefins is developed using cinchona alkaloids as the catalysts. Both product enantiomers are accessible with moderate to good enantioselectivity.     

Spinodal decomposition and droplets entrapment in monotectic solidification

In this article, we present two models to simulate solidification morphologies in monotectic alloys. With the first model, we investigate the morphological evolution under the influence of spinodal decomposition. The model requires that a gradient energy contribution for the concentration field should be incorporated, in order to stabilize phase separation when the liquid concentration is inside the region of miscibility gap. The free energy of the system in this model is derived from direct interpolation of the bulk energy densities. This, however, results in simulation regions in nanometer scale due to contributions from the chemical free energy of the system to the total surface excess. With the second model, our purpose is to develop a phase-field model to simulate scales that are larger than nanometer, where the departures from equilibrium are very small resulting in phase concentrations outside the spinodal region. In view of this, we exclude the concentration gradient contribution to the grand chemical potential functional, and develop a model based on [M. Plapp, Phys. Rev. E 84, 031601 (2011); A. Choudhury and B. Nestler, Phys. Rev. E 85, 021602 (2012)]. The advantage is that the free energy excess across the interface at equilibrium disappears, and hence it is easier to derive the required surface energies with higher interface widths. Due to this benefit, we employ the method to simulate the dynamic entrapment process in the monotectic reaction and study the influence of liquid(1) - liquid(2) surface energy and undercooling on the entrapment process.     

On solutions of third and fourth-order time dependent Riccati equations and the generalized Chazy system

We introduce a new transformation (nonlocal) to find the general solutions of some equations belonging to the third and fourth-order time dependent Riccati class of equations. These are in turn related to the Chazy polynomial class and the time dependent F-XVI Bureau symbol PI equations respectively.     

Characterisation of Polyurethane Coatings Using Thermoanalytical Techniques

A two-pack polyurethane coating was analyzed using thermoanalytical techniques. The curing reaction, monitored using pressure differential calorimetry (PDSC), rheometry and dynamic mechanical analysis (DMA) shows the temperature dependency of activation energy and hence rate of curing. In-situ ATR-FTIR shows the formation of urethane linkage over time. The decomposition behavior carried out under non-isothermal mode using thermogravimetric analysis (TGA) shows bimodal behavior. The activation energies of the initial step (10% decomposition) from both iso and non-isothermal experiments are in very good agreement with each other. The use of dynamic mechanical analysis (DMA) shows the difference in glass transition behavior (T_g) and elastic modulus (E') due to the different state of cure. Also the coating exhibits a very broad loss modulus peak (E') indicating higher energy dissipation with deformation.This revised version was published online in November 2005 with corrections to the Cover Date.     

Hydro­gen‐bonded adducts of ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol): monomeric and dimeric 1:1 adducts with 1,2‐bis(4‐pyridyl)­ethane and 1,2‐­diamino­ethane

In ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol)–4,4′‐ethyl­enedi­pyridine (1/1), [Fe(C₁₈H₁₅O)₂]·C₁₂H₁₂N₂, there is an intra­molecular O—H?O hydrogen bond in the ferrocenediol component and a single O—H?N hydrogen bond linking the two components into a finite monomeric adduct. Ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol)–ethyl­enedi­amine (1/1), [Fe(C₁₈H₁₅O)₂]·C₂H₈N₂, crystallizes with Z′ = 2 in space group P, and there are two independent four‐component aggregates in the structure, both of which are centrosymmetric. In the first type of aggregate, the molecular components are linked by O—H?N and N—H?O hydrogen bonds, in which both di­amine N atoms participate; in the second type of aggregate, the di­amine component is disordered over two sets of sites, but only one N atom is involved in the hydrogen bonding.     

A Remote State Preparation Scheme Initiated and Fixed by a Mentor

Physics of Particles and Nuclei Letters - In this paper we introduce the concept of mentor in the task of remote state preparation of a three-qubit quantum state. The role of the mentor is to...