Structural and conformational changes during thermally‐induced crystallization of poly(trimethylene terephthalate) by infrared spectroscopy

Conformational changes occurring during thermally‐induced crystallization of poly(trimethylene terephthalate) (PTT) by annealing have been studied using density measurement, differential scanning calorimetry (DSC), and mid‐infrared spectroscopy (MIR). Infrared spectra of amorphous and semicrystalline PTT were obtained, and digital subtraction of the amorphous contribution from the semicrystalline PTT spectra provided characteristic MIR spectra of amorphous and crystalline PTT. The normalized absorbance of 1577, 1173, and 976 cm^?1 were plotted against the crystallinity showing that these bands can be used unambiguously to represent the trans conformation while the band at 1358 cm^?1 can be used to represent gauche conformation of methylene segment. The presence of a weak band at 1358 cm^?1 in the amorphous spectrum suggested that a small amount of gauche conformation is present in the amorphous phase. Infrared spectroscopy has been used for the first time as a means to estimate the trans and gauche conformations of methylene segments in PTT as a function of T_a. The amount of gauche conformation was plotted against the crystalline fraction and the extrapolation of this plot to zero crystalline fraction provided a value of 0.07, suggested that the pure amorphous phase consist of ～ 7% gauche conformation. It was found that the amorphous and crystalline gauche conformation increases at the expense of amorphous trans conformation during thermally induced crystallization of PTT. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1497–1504, 2008     

On the partial trace over collective spin degrees of freedom

We derive analytical properties for the degeneracy ν(N,j) occurring in the decomposition of the state space C2⊗N. We also investigate the dynamics of two qubits coupled via Ising interactions to separate spin baths, and we study the thermodynamic limit.     

Polynomial integration over the unit sphere

The main objective of this work is the implementation of recursive formulas allowing the integration of a high order polynomial expression on the unit sphere. These formulas facilitate the evaluation of very complex computations. The proofs of the formulas are based on mathematical induction as well as the divergence theorem.     

A new biosynthesis of CuCo2S4 nanoparticles as a high-performance supercapacitor electrode and excellent non-enzymatic hydrazine sensor

In this work, we report the biosynthesis of CuCo₂S₄ nanoparticles (Bio-NPs) via hydrothermal method. The synthetized Bio-NPs-CuCo₂S₄ was studied as an active material of working electrode for electrochemical supercapacitor and non-enzymatic hydrazine sensor. The Bio.NPs-CuCo₂S₄/ITO electrode has a specific capacitance of 264 F/g at a current density of 1 A/g. Meanwhile, the electrode exhibits excellent electrochemical performances, such as an energy density of 33 Wh/Kg and a power density of 900 W/Kg. The Bio.NPs-CuCo₂S₄/ITO electrode for non-enzymatic hydrazine sensor exhibits a very high sensitivity of 2400 μA.mM⁻¹.cm⁻², a wide linear range from 0.001 to 1.400 mM and shows an excellent selectivity.