Direct Synthesis of Polycarbonate from Carbon Monoxide and Bisphenol A Using Efficient Pd Complex Catalyst Systems

A direct oxidative carbonylation procedure of Bisphenol A to polycarbonate catalyzed with efficient Pd complex systems has been developed. Pd/2,2′‐bipyridyl complexes possessing 6,6′‐dimethyl substituents, Pd/2,2′‐biquinoline complexes, and dinuclear Pd complexes bridged with a pyridylphosphine ligand were found to give higher molecular weights and yields than conventional Pd catalyst systems. Highest molecular weight (M̄_n = 5 600, M̄_w = 12 900) and yield (86%) were obtained using the Pd/6,6′‐dimethyl‐2,2′‐bipyridyl complex system.     

X‐ray analysis of the bisphenol‐A‐type macrocyclic carbonate trimer

Collection of the single crystal X‐ray refraction data of the Bisphenol‐A‐type Macrocyclic oligocarbonate trimer (c‐3mer) at room temperature was carried out. The single crystal of the cyclic trimer that is recrystallized from ethyl acetate showed solvent molecule in the center of macro ring. Similarly, cyclic tetramer (c‐4mer) contained two p‐xylene molecules. Smaller dimer (c‐2mer) did not afford co‐crystal with solvent. Conformation of the carbonate in c‐3mer was s‐cis and s‐cis as in c‐4mer. A relationship between the conformation of carbonate and noncatalyst polymerization activity was not found. Copyright © 2000 John Wiley & Sons, Ltd.     

Optimal eighth order convergent iteration scheme based on Lagrange interpolation

Acta Mathematicae Applicatae Sinica, English Series - In this paper, based on fourth order Ostrowski method, we derive an optimal eighth order iteration scheme for obtaining simple roots of...     

Structure factor of amorphous TiO2 nanoparticle; Molecular Dynamics Study

Three samples of amorphous TiO₂ of 3 nm size are prepared by molecular dynamics simulations using different heating and quenching rates and open boundary conditions. Matsui–Akaogi force field is used to calculate the correlation functions. It is found that atomic distribution in these samples differ within the limit of 4%. The calculated coordination numbers suggest that 52–54% Ti atoms are 6-fold coordinated, 31–32% Ti atoms are 5-fold coordinated, 7–10% are 4-fold coordinated and few Ti atoms even 7-fold coordinated through vertex and edge sharing in these samples. On the other hand 66–68% oxygen atoms remain 3-fold coordinated, 25–28% are 2-fold coordinated and 5–6% oxygen atoms become 4-fold coordinated. Most of the over coordinated and under coordinated strained structures are in the core and surface regions respectively. The agreement between the calculated and measured reduced structure factors suggests that atomic arrangements in the laboratory samples prepared by sputtering and sol-gel methods may be similar to those predicted by molecular dynamics simulations.     

Minimal spin-3/2 dark matter in a simple s-channel model

The European Physical Journal C - Recently in (Eur Phys J C 76:341, 2016), Myung has suggested that the renormalizability of massive conformal gravity is meaningless unless the massive ghost states...     

Bézier variant of the Jakimovski–Leviatan–Păltănea operators based on Appell polynomials

In this paper, we introduce the Bézier variant of the Jakimovski–Leviatan–P?lt?nea operators based on Appell polynomials. We establish some local results, a direct approximation theorem by means of the Ditzian–Totik modulus of smoothness and also study the rate of convergence for the functions having a derivative of bounded variation for these operators.