Limit Theorems for Orthogonal Polynomials Related to Circular Ensembles

For a natural extension of the circular unitary ensemble of order n, we study as \(n\rightarrow \infty \) the asymptotic behavior of the sequence of monic orthogonal polynomials \((\varPhi _{k,n}, k=0, \ldots , n)\) with respect to the spectral measure associated with a fixed vector, the last term being the characteristic polynomial. We show that, as \(n\rightarrow \infty \), the sequence of processes \((\log \varPhi _{\lfloor nt\rfloor ,n}(1), t \in [0,1])\) converges to a deterministic limit, and we describe the fluctuations and the large deviations.     

Kink formation and motion in carbon nanotubes at high temperatures

We report that kink motion is a universal plastic deformation mode in all carbon nanotubes when being tensile loaded at high temperatures. The kink motion, observed inside a high-resolution transmission electron microscope, is reminiscent of dislocation motion in crystalline materials: namely, it dissociates and multiplies. The kinks are nucleated from vacancy creation and aggregation, and propagate in either a longitudinal or a spiral path along the nanotube walls. The kink motion is related to dislocation glide and climb influenced by external stress and high temperatures in carbon nanotubes.     

Effect of methoxyl group position on the regioselectivity of ammonia substitution reactions involving 3,3'-dichloro-2,2'-binaphthoquinones

A series of methoxyl-substituted 3,3'-dichloro-2,2'-binaphthoquinones 2 were prepared and evaluated for regioselectivity in ammonia substitution reactions. Biquinone 2b underwent regiospecific amination at the unsubstituted chloronaphthoquinone unit whereas the isomeric biquinone, 2c, produced moderate regioselectivity (85:15). Biquinone 2d, however, showed no level of regioselectivity demonstrating that the position of the methoxyl group influences the regiochemistry. The intramolecular hydrogen bond in biquinone 5 altered the regioselectivity. Semiempirical calculations revealed comparatively larger LUMO coefficients at the chlorinated carbons that underwent preferential substitution.     

A novel life management model consists of chemical aging model and electrical-thermal aging model for power transformers using a new activation energy calculation method

Power transformers aging is investigated by a chemical aging model and an electrical-thermal aging model. In the chemical aging model, oil and cellulose chemical status are considered, but transformer load is not considered, while in the electrical-thermal model, only the effects of load and hotspot temperature are considered. The primary purpose of this paper is to combine both aging models to achieve a transformer life management model that considers the effect of all chemical parameters and the transformer load current simultaneously. Combining one chemical and one electrical-thermal aging model to reach a life management model for the transformer means that the remaining life of the transformer is first estimated using the chemical aging model by the provided equations for pre-exponential factor and activation energy in this paper. For this estimation, after conducting scientific studies, including experimental studies and computation on measurement results, an empirical mathematical equation will be presented to calculate the activation energy. Then using the presented equation, the remaining life will be estimated more accurately. Then, in the next step, this estimated life will be used in the electrical-thermal aging model and finally, a hotspot temperature will be calculated for the transformer. Finally, using the proposed hotspot temperature value and presented equations in this paper, a load current will be determined, which is recommended that the transformer load should not exceed that value. Finally, the proposed equation for activation energy calculation and the presented life management model validation will be verified using some transformers measurement results.

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Versatile mass excited impact oscillator

Nonlinear Dynamics - This paper presents the design and the initial experimental results of a novel impact oscillator rig developed by the Centre of Applied Dynamic Research at the University of...     

Molecular Interactions in [Hmim][NO3] Ionic Liquid and 2-Alkanol Mixtures: Kirkwood–Buff Integrals and Structure Factor

Russian Journal of Physical Chemistry A - In this paper, the investigation on thermophysical properties, structure, and dominant interactions in the binary systems containing...     

L-lysine-Pd Complex Supported on Fe3O4 MNPs: a novel recoverable magnetic nanocatalyst for Suzuki C-C Cross-Coupling reaction

In this work, L-lysine-Pd Complex, immobilized onto the surface of Fe₃O₄ MNPs, was successfully prepared via simple and inexpensive procedure. The prepared nanocatalyst was considered as a robust and clean nano-reactor catalyst for the Suzuki and Heck C-C Cross-Coupling reactions in water as the green condition. This eco-friendly heterogeneous catalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), X-Ray Diffractometer (XRD), energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma atomic emission spectroscopy (ICP), X-ray mapping, BET, thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) techniques. The use of a green medium, easy separation and workup, excellent reusability of the nanocatalyst and short reaction time are some outstanding advantages of this method.     

A proton magnetic resonance study of the conformation of the seven-membered ring in benzocycloheptene

The computer analysis of the PMR spectra of several partially deuterated benzocycloheptene derivatives at ?120° provides values for all the coupling constants about the C₃? C₄ bond. An interpretaion using the Karplus equation shows unambiguously that the seven-membered ring exists as a chair conformation. The relationship between the coupling constants determined shows that the form of the Karplus equation established empirically for cyclohexane is applicable to this seven-membered ring. A comparison of coupling constants shows that the benzocycloheptene chair is more puckered than the cyclohexane chair.