Finite size effects on structure and magnetism in mass-selected CoPt nanoparticles

In this paper, the one-way absorption property in one-dimensional dielectric/metal photonic crystal structure with a dielectric defect layer is studied. The effects of incident angle and state of polarization on one-way absorption behaviour of the anti-resonant (AR) mode are investigated. The normally incident wave from left to right propagation is totally allowed to penetrate to the structure but right to left propagation totally reflected at the same wavelength. It is found that, with increasing of the incident angle, the AR mode shifts to the lower wavelengths and its intensity decreases. Simultaneously, another AR mode with reversed one-way property appears at higher wavelength. The one-way behaviour on absorption is observed at the both states of polarizations but is localized on different wavelengths. Those effects, are suggesting that the proposed structure can be used as a direction sense polarization splitter or reflector/antireflector device.     

A Matrix Interpolation between Classical and Free Max Operations. I. The Univariate Case

Recently, Ben Arous and Voiculescu considered taking the maximum of two free random variables and brought to light a deep analogy with the operation of taking the maximum of two independent random variables. We present here a new insight on this analogy: its concrete realization based on random matrices giving an interpolation between classical and free settings.     

Diabatic investigation for the NaRb molecule

An extensive diabatic investigation of the NaRb species has been carried out for all excited states up to the ionic limit Na^‐Rb⁺. An ab initio calculation founded on the pseudopotential, core polarization potential operators and full configuration interaction has been used with an efficient diabatization method involving a combination of variational effective hamiltonian theory and an effective overlap matrix. Diabatic potential energy curves and electric dipole moments (permanent and transition) for all the symmetries Σ⁺, Π, and Δ have been studied for the first time. Thanks to a unitary rotation matrix, the examination of the diabatic permanent dipole moment (PDM) has shown the ionic feature clearly seen in the diabatic ¹Σ⁺ potential curves and confirming the high imprint of the Na^‐Rb⁺ ionic state in the adiabatic representation. Diabatic transition dipole moments have also been computed. Real crossings have been shown for the diabatic PDM, locating the avoided crossings between the corresponding adiabatic energy curves.     

Structure of sodiated octa-glycine: IRMPD spectroscopy and molecular modeling

The structure of the sodiated peptide GGGGGGGG-Na⁺ or G₈-Na⁺ was investigated by infrared multiple photon dissociation (IRMPD) spectroscopy and a combination of theoretical methods. IRMPD was carried out in both the fingerprint and N—H/O—H stretching regions. Modeling used the polarizable force field AMOEBA in conjunction with the replica-exchange molecular dynamics (REMD) method, allowing an efficient exploration of the potential energy surface. Geometries and energetics were further refined at B3LYP-D and MP2 quantum chemical levels. The IRMPD spectra indicate that there is no free C-terminus OH and that several N—Hs are free of hydrogen bonding, while several others are bound, however not very strongly. The structure must then be either of the charge solvation (CS) type with a hydrogen-bound acidic OH, or a salt bridge (SB). Extensive REMD searches generated several low-energy structures of both types. The most stable structures of each type are computed to be very close in energy. The computed energy barrier separating these structures is small enough that G₈-Na⁺ is likely fluxional with easy proton transfer between the two peptide termini. There is, however, good agreement between experiment and computations in the entire spectral range for the CS isomer only, which thus appears to be the most likely structure of G₈-Na⁺ at room temperature.     

Improvement of the recursive projection method for linear iterative scheme stabilization based on an approximate eigenvalue problem

An algorithm for stabilizing linear iterative schemes is developed in this study. The recursive projection method is applied in order to stabilize divergent numerical algorithms. A criterion for selecting the divergent subspace of the iteration matrix with an approximate eigenvalue problem is introduced. The performance of the present algorithm is investigated in terms of storage requirements and CPU costs and is compared to the original Krylov criterion. Theoretical results on the divergent subspace selection accuracy are established. The method is then applied to the resolution of the linear advection–diffusion equation and to a sensitivity analysis for a turbulent transonic flow in the context of aerodynamic shape optimization. Numerical experiments demonstrate better robustness and faster convergence properties of the stabilization algorithm with the new criterion based on the approximate eigenvalue problem. This criterion requires only slight additional operations and memory which vanish in the limit of large linear systems.     

Inference and phase transitions in the detection of modules in sparse networks

We present an asymptotically exact analysis of the problem of detecting communities in sparse random networks generated by stochastic block models. Using the cavity method of statistical physics and its relationship to belief propagation, we unveil a phase transition from a regime where we can infer the correct group assignments of the nodes to one where these groups are undetectable. Our approach yields an optimal inference algorithm for detecting modules, including both assortative and disassortative functional modules, assessing their significance, and learning the parameters of the underlying block model. Our algorithm is scalable and applicable to real-world networks, as long as they are well described by the block model.     

Contribution of microextraction in packed sorbent for the analysis of cotinine in human urine by GC–MS

A simple, rapid, sensitive, and non-consuming solvent method for the determination of cotinine in urine was developed, based on sample preparation by the relatively new technique microextraction in packed sorbent (MEPS) and analysis by GC–MS. This optimized method was compared with conventional solid-phase extraction/liquid–liquid extraction method used as reference. The wide linear range (5–5,000 ng/mL) and high sensitivity of the MEPS method (limit of detection 0.8 ng/mL) allow application to analysis of urine from smokers as well as non-smokers susceptible to passive smoking.     

π‐Expanded α,β‐Unsaturated Ketones: Synthesis,Optical Properties,and Two‐Photon‐Induced Polymerization

A library of π‐expanded α,β‐unsaturated ketones was designed and synthesized. They were prepared by a combination of Wittig reaction, Sonogashira reaction, and aldol condensation. It was further demonstrated that the double aldol condensation can be performed effectively for highly polarized styrene‐ and diphenylacetylene‐derived aldehydes. The strategic placement of two dialkylamino groups at the periphery of D ‐π‐A‐π‐D molecules resulted in dyes with excellent solubility. These ketones absorb light in the region 400–550 nm. Many of them display strong solvatochromism so that the emission ranges from 530–580 nm in toluene to the near‐IR region in benzonitrile. Ketones based on cyclobutanone as central moieties display very high fluorescence quantum yields in nonpolar solvents, which decrease drastically in polar media. Photophysical studies of these new functional dyes revealed that they possess an enhanced two‐photon absorption cross section when compared with simpler ketone derivatives. Due to strong polarization of the resulting dyes, values of two‐photon absorption cross sections on the level of 200–300 GM at 800 nm were achieved, and thanks to that as well as the presence of the keto group, these new two‐photon initiators display excellent performance so that the operating region is 5–75 mW in some cases.