On modifying properties of polymeric melts by nanoscopic particles

We study geometric and energetic factors that partake in modifying properties of polymeric melts via inserting well‐dispersed nanoscopic particles (NP). Model systems are cis‐1,4‐polybutadiene melts including a single atomic clusters of size varied in the range 10–150 atoms (3–7 Å in radius; 0.1–1.5% v/v). We modify the interactions between the chains and the particle by tuning attractive van der Waals interactions. Using molecular dynamics, we study equilibrium fluctuations and dynamical properties at the interface. The NPs move in the polymer matrix in two different regimes corresponding to trapped and free diffusion, depending on the NP size. Furthermore, degree of crowding around the NP by the polymer chains is quantified. Effect of NP size and interaction strength both on volume and volumetric fluctuations is manifested in mechanical properties, quantified here by bulk modulus, K. Tuning NP size and nonbonded interactions results in ～15% enhancement in K by addition of a maximum of 1.5% v/v NP. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Control of Ionization in the Interaction of Strong Laser Fields with Dense Nanoplasmas

Different experimental methods to maximize the yield of highly charged ions in silver and xenon clusters interacting with intense and ultra‐short optical laser pulses are discussed. Theoretically, the interaction of strong laser fields with clusters is investigated within the nanoplasma model. The time evolution of the laser intensity has been parametrized. The free optimization of the parameters with a genetic algorithm is an effective but expensive tool to control the plasma dynamics. Comparison is given to the parametric control method in which pulse separation and relative intensity ratio of double‐pulses are varied. This method delivers in the case of silver and xenon clusters pulses quite close to the optimal pulse shape (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Substituent Effect on the Electronic Structure of Sulfines: Molecular Orbital Treatment

The electronic structure and ground state properties of the gaseous sulfine H₂CSO and some of its derivatives were studied at the RHF, MP2, and B3LYP levels. The calculations showed that the Z-isomer is more stable than the E-one and their difference in energy depends on their level of calculation, basis set, and substituent. The factors affecting the isomer stability are the electrostatic interactions, the steric factor, and π-electrons delocalization. The substituent has little effect on the geometry of the CSO moiety but greatly affects its charge distribution and polarizability. The ΔE value of the E- to Z-isomerization process via rotation of the S═O bond was calculated. The substituent has an appreciable effect on both the geometry and energy barrier of isomerization depending on its electronegativity, electrostatic attraction, and effect on π-delocalization over the molecule.     

Conformational and Electronic Interaction Studies of Some β-Ketosulfoxides

ABSTRACT.

The analysis of the carbonyl I.R. band and the U.V. phoelectron spectroscopic data along with the ab-initio calculations and X-ray diffraction of α-(methylsulfinyl)- and α-(phenylsulfinyl)-acetophenones indicated the predominance of the cis rotamers over the qauche ones.     

Magnetic behavior of a nano-disk constrained in an antiferromagnetic substrate

In this work we report a numerical Monte Carlo study of the behavior of a magnetic nano-disk put over an antiferromagnetic substrate. Three approaches were considered for describe the substrate: (1) A stacked antiferromagnetic configuration, (2) an Ising like arrangement and (3) Heisenberg like spins. For the Heisenberg case we still have considered an easy-plane and an easy-axis symmetry of the substrate. The hysteresis loop for the nano-disk is obtained by considering the three cases. The signature of the vortex in the nano-disk appears as small jumps in the hysteresis curve. Exchange bias effects are observed since the substrate has an easy axis symmetry.     

Realization of superposition and entanglement of coherent and squeezed states in circuit quantum electrodynamics

We propose a new scheme for generating the superposition and entanglement of the coherent states and squeezed states by considering N superconducting charge qubits (or artificial two-level atoms) interacting with photons in a high finesse cavity on a chip, assisted by a strong driving field. By virtue of the parameters of this system, we can generate novel quantum states, for example, multiparty entangled states and Schro¨dinger cat states among the superconducting qubits, coherent states and squeezed state...     

Generation of Bell states via Lyapunov control on a two-qubit system with an anisotropic XY Heisenberg interaction

We demonstrate that an arbitrary Bell state can be achieved in a two qubit anisotropic Heisenberg XY chain via Lyapunov control. During the whole process, we only need to apply an external field along a given direction to a single qubit. This control strategy is effective for all initial states in the four-dimensional Hilbert space where the target state is asymptotically stable. The effects of imperfections on the fidelity for the target state such as Gaussian leakage of local control and localized dephasi...     

Mannose‐based graft polyesters with tunable binding affinity to concanavalin A

Glycopolymers have been widely used to understand the interactions between carbohydrates and lectins, which facilitate the diagnosis and detection of disease and pathogens as well as the development of vaccines. While studies have been focused on the correlation of glycopolymer structure and their binding to lectins, graft‐type glycopolyesters are uncommon. Herein, we report the design and synthesis of mannose‐based graft polyesters by “grafting‐from” method and investigate their interactions with Concanavalin A (Con A). As confirmed by ¹H NMR spectroscopy and sulfuric acid‐UV method, graft polyesters with different lengths of mannose graft were successfully synthesized. Our results from turbidimetry binding assay showed that graft polyesters with longer mannose graft exhibit higher initial binding rate (k_i). Isothermal titration calorimetry measurements of these graft polyesters with Con A showed that polymers exhibit higher binding affinity (k_a) with the number of side chain mannose. This study provides understanding of the interaction between Con A and mannose‐based graft polyesters, which can be employed for the development of glycopolymeric therapeutics. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3908–3917     

Syntheses,structures, and properties of Ni(II) complexes with 5,5′-bis(4-halogenphenyl)diazo-dipyrromethane

Ni(II) complexes with 5,5′-bis(4-halogenphenyl)diazo-dipyrromethane have been synthesized and characterized by X-ray crystallography. All the complexes have similar crystal structures in which Ni(II) is square-planar by coordinating to two pyrrole and two azo nitrogen atoms. The azo-pyrroles of the ligands can be converted to the hydrazone tautomer after complexing nickel. Moreover, the C–H?···?Ni interaction played an important role in directing self-assembly of the complexes. The UV-Vis spectra of the complexes showed great difference with the metal complexes of pyrrol-2-imine.