Charge transfer in keV proton collision with atomic oxygen: Differential and total cross sections

Classical Trajectory Monte Carlo method (CTMC) with the modal interaction potential [1] has been used to simulate the differential, total and partial capture cross sections in proton-oxygen atom collisions in the energy range of 0.5–200 keV. An interesting feature of the calculated differential cross sections (DCS) curve below the scattering angle 0.1^○ is the presence of oscillations showing asymmetry in angular positions. The oscillations in the partial cross sections are explained in terms of swapping effect. The DCS and total cross sections are found to be in good agreement with the experimental as well as other theoretical results.     

Ultrasonic wave propagation in IIIrd group nitrides

The ultrasonic attenuation in hexagonal structured (wurtzite) third group nitrides (GaN, AlN and InN) has been evaluated at 300 K for an ultrasonic wave propagating along the unique axis of the crystal. Higher order elastic constants of these materials are calculated using the Lennard-Jones potential for the determination of ultrasonic attenuation. The ultrasonic velocity, Debye average velocity, thermal relaxation time and acoustic coupling constant are evaluated along the z-axis of the crystal using the second order elastic constants and other related parameters. The contributions of the elastic constants, thermal conductivity, thermal energy density, ultrasonic velocity and acoustic coupling constant to the total attenuation are studied. On the basis of the ultrasonic attenuation, it can be concluded that the AlN is more ductile than either GaN or InN at 300 K. Orientation dependent characterization has been achieved by calculation of the orientation dependent ultrasonic velocity, Debye average velocity and thermal relaxation time for the materials.     

Driven Chain Macromolecule in a Heterogeneous Membrane-Like Medium

Monte Carlo simulations are performed to study the conformational relaxation of a large polymer chain driven into a heterogeneous (membranelike) substrate on a discrete lattice. Chains are created on trails of constrained self-avoiding walks (SAW) on the lattice. Kink–jump, crank–shaft, and reptation moves are used to move segments of chains. Short chains of length L _sc are driven by a field E ₁ toward an impenetrable substrate to design a membrane medium with mobile chain segments. A long chain of length L _lc is then driven by a field E ₂ into the membrane medium and is subsequently allowed to relax in a field E ₃. Radius of gyration R _g and end-to-end distance R _e of the long chain are examined. The relaxation of the conformation of the long chain and its magnitude is found to depend on the initial (predeposition) conformation of the chain, i.e., on E ₂. For a relatively relaxed initial conformation (at E ₂ = 0.1), the longitudinal component of the radius of gyration (R _gz ) is found to decay with the driving field E ₃ with a power law, R _gz E ₃ where 0.1 at low field (E ₃ 0.1) and 1/3 at high field E ₃ 0.1.     

Metal germylyne complexes [Mtbd1;Ge-R] and metallogermylenes [M-Ge-R]: DFT analysis of the systems [(Cp)(CO)(n)()Mtbd1;GeMe] (M = Cr,Mo, W,Fe(2+), n = 2; M = Fe,n = 1) and [(Cp)(CO)(n)()M-GeMe] (M = Cr,Mo, W,n = 3; M = Fe,n = 2)

Quantum chemical calculations at the gradient corrected DFT level using the exchange correlation functionals BP86 and B3LYP of the geometries of the title compounds are reported. The theoretically predicted bond lengths and angles of the model compounds are in excellent agreement with experiment. The nature of the metal-ligand interactions is quantitatively analyzed with an energy decomposition method. The analysis of the electronic structure of the neutral metal germylyne complexes Ia-Id and the metallogermylenes IIa-IId shows that the former compounds have about the same degree of electrostatic and covalent bonding, while the relative strength of the covalent contributions in the latter molecules is lower (41-42%) than the electrostatic attraction (58-59%). The a' '(pi) bonding contribution in the group-6 germylyne complexes Ia-Ic is rather high (42% of the orbital interactions). In the iron complex Id, it is even higher (53.8%) than the sigma bonding. The pi bonding contributions to the covalent bonding become much less (18-20%) in the metallogermylenes IIa-IId.     

Weak amenability of Segal algebras

Let be a locally compact abelian group, and let . We show that the Segal algebra is always weakly amenable, but that it is amenable only if is discrete.

     

Molecular docking,experimental FT-IR spectra,UV–Vis spectra,vibrational analysis,electronic properties,Fukui function analysis of a potential bioactive agent – Proflavine

Proflavine, having the molecular formula C₁₃H₁₁N₃, is a well-known urinary antiseptic and anticancer medication (3,6-diaminoacridine). In this communication, Quantum chemical computations of Proflavine's geometry have been performed and examined in the ground state. The optimized structure and wavenumbers of the molecule's vibrational bands were investigated using the DFT/B3LYP method and 6–311G (d, p) as the basis set. The calculated vibrational frequencies are compared to experimental IR spectra. The link between thermodynamic characteristics and temperature has been studied. The computed IR frequencies correlate well with the experiments, as indicated by the correlation factor (R² = 0.99). The UV spectra of the title molecule are calculated by using Time Dependent Density Functional Theory (TD-DFT). The molecule's interactions with other species were described using an analysis of a HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital). Natural bond orbitals (NBO) analysis was used to investigate intramolecular and intermolecular hydrogen bonding and their second-order stabilization energies and conjugative and hyperconjugative interactions. By computing the first hyperpolarizability, nonlinear optical (NLO) analysis was utilized to explore the molecule's nonlinear optical properties.     

Graphene Defects in Saccharide Carbon Dots Govern Electrochemical Sensitivity

Galactose (Gal), lactose (Lac), and glucose (Glu) derived carbon dots (CDs) were evaluated for their utility as electrochemical sensing composites using acetaminophen (APAP) as a probe molecule. The goal of this work is to ascertain the role of graphene defects on electrochemical activity. Higher sp²-to-sp³ hybridized carbon ratios (in parentheses) in the CDs correlated with higher sensitivity in the order according to measured Raman I_G/I_D intensities: GluCDs (6.53)<LacCDs (9.30)<GalCDs (10.18). A dynamic measurement in the 0–2.0 mmol dm⁻³ APAP range at pH=7.0 was achieved, suitable for practical APAP toxicity monitoring. Defect density within the GalCDs provided the highest sensitivity.     

Supramolecular Control on the Optical Properties of a Dye-Polyelectrolyte Assembly

Control of fluorescent molecular assemblies is an exciting area of research with large potential for various important applications, such as, fluorescence sensing/probing, cell imaging and monitoring drug-delivery. In the present contribution, we have demonstrated control on the extent of aggregation of a dye-polyelectrolyte assembly using a macrocyclic host molecule, sulfobutylether-β-cyclodextrin (SBE-β-CD). Initially, a cationic molecular rotor based organic dye, Auramine-O (AuO), undergoes aggregation in the presence of an anionic polyelectrolyte, polystyrene sulfonate (PSS), and displays a broad intense new emission band along with large variation in its absorption features and excited-state lifetime. A manipulation of the monomer-aggregate equilibrium of the dye-polyelectrolyte assembly has been achieved by introducing a cyclodextrin based supramolecular host, SBE-β-CD, which leads to relocation of AuO molecules from polyelectrolyte (PSS) to supramolecular host cavity, owing to the formation of a host-guest complex between AuO and SBE-β-CD. A reversible control on this manipulation of monomer-aggregate equilibrium is further achieved by introducing a competitive guest for the host cavity i. e., 1-Adamantanol. Thus, we have demonstrated an interesting control on the dye-polyelectrolyte aggregate assembly using a supramolecular host molecule which open up exciting possibilities to construct responsive materials using a repertoire of various host-specific guest molecules.