Mono‐ and Bis(pyrrolo)tetrathiafulvalene Derivatives Tethered to C60: Synthesis,Photophysical Studies,and Self‐Assembled Monolayers

A series of mono‐ (MPTTF) and bis(pyrrolo)tetrathiafulvalene (BPTTF) derivatives tethered to one or two C₆₀ moieties was synthesized and characterized. The synthetic strategy for these dumbbell‐shaped compounds was based on a 1,3‐dipolar cycloaddition reaction between aldehyde‐functionalized MPTTF/BPTTF derivatives, two different tailor‐made amino acids, and C₆₀. Electronic communication between the MPTTF/BPTTF units and the C₆₀ moieties was studied by a variety of techniques including cyclic voltammetry and absorption spectroscopy. These solution‐based studies indicated no observable electronic communication between the MPTTF/BPTTF units and the C₆₀ moieties. In addition, femtosecond and nanosecond transient absorption spectroscopy revealed, rather surprisingly, that no charge transfer from the MPTTF/BPTTF units to the C₆₀ moieties takes place on excitation of the fullerene moiety. Finally, it was shown that the MPTTF–C₆₀ and C₆₀–BPTTF‐C₆₀ dyad and triad molecules formed self‐assembled monolayers on a Au(111) surface by anchoring to C₆₀.     

Identification of groundwater discharge in Cuddalore coast,Tamil Nadu using radium isotopes

For the optimal exploitation and management of coastal aquifers of Tamil Nadu, it is essential to evaluate the groundwater outflow into the sea also called as submarine groundwater discharge. In this study, radium isotopes (^223,224Ra) were employed to understand the groundwater discharge in coastal areas of Cuddalore district, Tamil Nadu. Sea water samples (100 L) were collected from various locations of Cuddalore coast in October 2011 and passed through Mn-impregnated acrylic fiber columns. These acrylic columns were analyzed for ^223,224Ra activities using radium delayed coincidence counter. The observed higher activities of ^223,224Ra excess (0.02 ± 0.001–3.28 ± 0.16 and 64 ± 3–380 ± 19 mBq/100 L respectively) indicate that groundwater discharge occurs in this coastal region.     

New hybrid [2]catenanes based on a 4,4'-bipyridinium ligand

The self-assembly-mediated synthesis of metallomacrocycles 4a and 4b from (en)M(NO3)2 (M = Pd, Pt) and bipyridinium ligand 3 is described. The reaction is templated by disodium p-phenyldiacetic dicarboxylate, which is inserted into the macrocyclic cavity. Similarly, the self-assembly process between ligand 3, (en)M(NO3)2 (M = Pd, Pt), and the macrocyclic polyether 6 resulted in the formation of hybrid catenanes 7a and 7b. In the [2]catenanes, the circumrotation of the macrocyclic polyether through the cavity of the metallocycle is slow on the 1H NMR time scale.     

Alumina-supported SAPO-34 membranes for CO2/CH4 separation

SAPO-34 membranes were prepared by in situ crystallization on alpha-Al2O3 porous supports. The crystal size of the seeds was effectively controlled in the 0.7 to 8.5 micron range by employing different structure-directing agents. Seeds smaller than 1 micron produced membranes with CO2/CH4 separation selectivities higher than 170 and unprecedented CO2 permeances as high as 2.0 x 10(-6) mol/m2.s.Pa at 295 K and a feed pressure of 224 kPa. The membranes effectively separated CO2/CH4 mixtures up to 1.7 MPa.     

Analysis of chemical shift changes reveals the binding modes of isoindolinone inhibitors of the MDM2-p53 interaction

In this study we present a method for defining the binding modes of a set of structurally related isoindolinone inhibitors of the MDM2-p53 interaction. This approach derives the location and orientation of isoindolinone binding, based on an analysis of the patterns of magnitude and direction of chemical shift perturbations for a series of inhibitors of the MDM2-p53 interaction. The MDM2-p53 complex is an attractive target for therapeutic intervention in cancer cells with intact tumor suppressor p53, as it offers the possibility of releasing p53 by blocking the MDM2-p53 binding site with a small molecule antagonist to promote apoptosis. Isoindolinones are a novel class of MDM2-antagonists of moderate affinity, which still require the development of more potent candidates for clinical applications. As the applicability of conventional structural methods to this system is limited by a number of fundamental factors, the exploitation of the information contained in chemical shift perturbations has offered a useful route to obtaining structural information to guide the development of more potent compounds. For a set of 12 structurally related isoindolinones, the data suggests 4 different orientations of binding, caused by subtle changes in the chemical structure of the inhibitors.     

Existence of Pulsating Roll-Waves for the Saint Venant System

The phenomenon of roll-waves occurs when shallow water flows down open inclined channels. This flow is described by the Saint Venant’s equations with a friction term due to Chezy. In the case of a flat bottom, their existence (as entropic and periodic travelling waves) follows from a classical work due to DRESSLER [6]. The aim of this paper is to prove the existence of roll-waves when the bottom is modulated by a small periodic perturbation. Following JIN and KATSOULAKIS [15], we first compute a Burgers-type equation which possesses “pulsating” roll-waves (the wave speed oscillates around an average velocity). We prove, in a mathematically rigorous fashion, the existence of these solutions.     

Adaptive Modelling,Simulation and Optimization of Gas and Water Supply Networks

We consider the simulation and optimisation of transport processes through gas and water supply networks. Using a consistent modeling of the network, adjoint equations for the whole system including initial, coupling and boundary conditions can be derived. These are suitable to compute gradients for optimization tasks but can also be used to estimate the accuracy of models and the discretization with respect to a given cost functional. We show the applicability of an adaptive algorithm that automatically steers the discretization and models while maintaining a given accuracy in an optimisation framework. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Manifestations of probe presence on probe dynamics in supercooled liquids

Experimental studies that follow behavior of single probes embedded in heterogeneous systems are increasingly common. The presence of probes may perturb the system, and such perturbations may or may not affect interpretation of host behavior from the probe observables typically measured. In this study, the manifestations of potential probe-induced changes to host dynamics in supercooled liquids are investigated via molecular dynamics simulations. It is found that probe dynamics do not necessarily mirror host dynamics as they exist either in the probe-free or probe-bearing systems. In particular, for a binary supercooled liquid, we find that smooth probes larger than the host particles induce increased translational diffusion in the host system; however, the diffusion is anisotropic and enhances caging of the probe, suppressing probe translational diffusion. This in turn may lead experiments that follow probe diffusion to suggest Stokes-Einstein behavior of the system even while both the probe-free and probe-bearing systems exhibit deviations from that behavior.