A process–structure–property study of anisotropic PMDA-ODA films

A practical methodology for the correlation and prediction of the process–property performance of advanced materials is developed. The model polymer studied is PMDA-ODA polyimide. The connecting link between the process and the properties is the structural state of the polymer. An essential ingredient for a quantitative characterization of the system is a knowledge of its phase state and intrinsic molecular properties. The intrinsic molecular properties define the limiting performance properties available to the polymer. Anisotropic films and sheets produced by five different fabrication processes are examined. Maps of the molecular symmetry axis, the orientation function, and the thickness distributions of two 50-in.-wide sheets fabricated differently are measured nondestructively for process comparison. Four other film fabrication processes are examined and their three-dimensional orientation states determined and correlated. A three-dimensional orientation function triangular plot permits simultaneous representation of the different fabrication processes on the same figure and allows the investigator to choose the most economic and efficient fabrication route. The structure–property study includes the structural correlation and intrinsic molecular property determination of the anisotropic coefficient of thermal expansion (CTE), the anisotropic mechanical moduli and compliances, and the anisotropic dielectric constants. 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 777–788, 1997     

ChemInform Abstract: X-Ray Diffraction,EPR, and 6Li and 27Al MAS NMR Study of LiAlO2—LiCoO2 Solid Solutions.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Markov and semi-Markov option pricing models with arbitrage possibility

The aim of this paper is the presentation of new models for option pricing that are discrete in time and in the framework of Markov and semi-Markov processes as an alternative to the classical Cox–Rubinstein model, and that also allow the possibility of arbitrage. Both cases of European and American options are considered and possible extensions are given. © 1997 by John Wiley & Sons, Ltd.     

Nonlinear fluorescence through intermolecular energy transfer and resolution increase in fluorescence microscopy

We investigate a novel concept to efficiently generate multiphoton induced fluorescence from organic molecules. The concept is based on frustrating the energy transfer between a fluorescent donor and one or more acceptors in conjugated molecules. The nonlinearity is not based on higher order molecular susceptibilities but entirely on their linear properties. Therefore, in contrast to nonresonant multiphoton absorption, this method does not require high local intensities. Likewise, the production of visible fluorescence does not require an infrared excitation wavelength. Hence, when applied to scanning microscopy this property is predicted to increase spatial resolution. Instead of the ∼10 GW/cm² required in non-resonant multiphoton excitation, focal intensities ∼10 MW/cm² are expected to produce an equally strong nonlinear signal. The predicted resolution is up to 30% greater than that of an ideal confocal microscope operating at the same fluorescence wavelength. The resolution improvement over non-resonant two-photon absorption microscopes is about two-fold in all directions.     

探测器点阵法测量激光光斑参数的仿真

 仿真分析了用均匀分布的探测器点阵测量激光光斑方法中,探测器灵敏度的线性工作动态范围,灵敏度的一致性差异,点阵间距等参数和光斑质心位置的测量误差,光束总能量的测量误差,以及光斑的分布等。仿真结果表明,当探测器灵敏度的一致性差异小于10％,线性工作范围的动态范围大于30dB,点阵间距小于光斑直径的1/5时,光束总能量的误差小于6％,光斑质心位置的测量误差小于光斑直径的2％,拟合的光斑分布和实际光斑分布比较接近。     

Recent Advances in Aerosol‐Assisted Spray Processes for the Design and Fabrication of Nanostructured Metal Chalcogenides for Sodium‐Ion Batteries

Increasing demand for sodium‐ion batteries (SIBs), one of the most feasible alternatives to lithium ion batteries (LIBs), has resulted because of their high energy density, low cost, and excellent cycling stability. Consequently, the design and fabrication of suitable electrode materials that govern the overall performance of SIBs are important. Aerosol‐assisted spray processes have gained recent prominence as feasible, scalable, and cost‐effective methods for preparing electrode materials. Herein, recent advances in aerosol‐assisted spray processes for the fabrication of nanostructured metal chalcogenides (e.g., metal sulfides, selenides, and tellurides) for SIBs, with a focus on improving the electrochemical performance of metal chalcogenides, are summarized. Finally, the improvements, limitations, and direction of future research into aerosol‐assisted spray processes for the fabrication of various electrode materials are presented.     

Evolution processes of coupled thermal qubits

We investigate the quantum speed limit time (QSLT) of quantum evolution before thermal equilibrium of two coupled qubits each of which is coupled to a separate thermal bath at the same temperature within the Born-Markov approximation. The evolution process in one particular initial state can change between speed-up and speed-down two times before reaching equilibrium. We call this double cusp behaviour. This behaviour is an anomalous phenomenon in evolution processes in the weak-coupling Markovian regime. We study QSLT corresponding to all pure initial energy eigenstates and categorise them. In addition, we also display the conditions for double cusp behaviour in terms of temperature, qubit interaction and frequency.     

两指标B值鞅空间的对偶

通过引入新型两指标B值鞅空间, 利用两指标B值鞅的Fefferman不等式, 证明了当B为自反Banach空间时, 由p均方算子定义的两指标B值鞅空间_pH_α     

Asymmetric Coupling in Two-Lane Asymmetric Simple Exclusion Processes with Unequal Injection Rates: Effect of Different Hoping Rates

This paper investigates the effect of both unequal injection rates and different hopping rates on two-lane asymmetric simple exclusion processes(ASEPs) with asymmetric coupling. When the hopping rates of both lanes are different, the system includes six steady phases, however, when the hopping rates of both lanes are same, the seventh phase(MC, MC) will exist in the system. Interestingly, with different hopping rates of both lanes, the densities of the system cannot be influenced by the non-zero vertical transition rate. Our theoretical arguments are in well agreement with extensively performed Monte Carlo simulations.