Dechlorination of poly(vinyl chloride) by 1-butyl-3-methylimidazoliumhydroxide

Highly efficient dechlorination of PVC has been realized at 180 °C and at atmospheric pressure, using 1-butyl-3-methylimidazoliumhydroxide ([Bmim]OH) as an environment-friendly reaction medium: in the absence of an external base or solvent the dechlorination efficiency is as high as 91.2%, while it is only 38.1% for PVC without ionic liquids. The dechlorination process follows first-order kinetics with apparent activation energy of 44 kJ mol⁻¹. Mechanistic analysis provides evidence for the equilibrium presence of carbene species, together with the hydroxide ions in [Bmim]OH, thus enhancing the dechlorination of PVC via a combined elimination and substitution mechanism.     

Synthesis and characterization of rodlike liquid crystalline polyester/multi-walled carbon nanotubes and study of their thermal stability

Rodlike thermotropic liquid crystalline polyester (TLCP) was synthesized from 4,4′-oxydibenzoyl chloride and resorcinol containing modified multi-walled carbon nanotubes (MWCNTs) by in situ high-temperature solution polymerization. The liquid crystalline properties and thermal stability of the resulted TLCP nanocomposites were characterized by XRD, DSC, TGA, SEM, POM, and optical analysis. The addition of small amount of MWCNTs into TLCP matrix could significantly improve the thermal stability. The mesophase temperature range of nanocomposites were widened and shifted to higher temperatures. This nanocomposite melting phase transition (T_m) value increases maximally to 38.4 °C compared with pure copolymer. Using the Horowits-Metzger kinetic method, the PE/M-0.5 gave the best performance in terms of the thermal stability. This result can be explained that the incorporation of MWCNTs into TLCP caused an interaction between TLCP and MWCNTs through π-π* conjugation.     

The proper interpolation space for multivariate Birkhoff interpolation

Multivariate Birkhoff interpolation problem has many important applications, such as in finite element method. In this paper two algorithms are given to compute the basis of the minimal interpolation space and the lower interpolation space respectively for an arbitrary given node set and the corresponding interpolation conditions on each node. We can get the monomial basis, Newton-type basis as well as Lagrange-type basis. The interpolation polynomial can be derived from the basis directly.     

Exploring the cause of the dual allosteric targeted inhibition attaching to allosteric sites enhancing SHP2 inhibition

Molecular Diversity - SHP2 is a protein tyrosine phosphatase (PTP) that can regulate the tyrosine phosphorylation level. Overexpression of SHP2 will promote the development of cancer diseases, so...     

Orbital selection of the double [CuO2] layer compound Ca3Cu2O4Cl2

We present a first-principles investigation on the dynamics and mechanism of the oxidation reaction between water molecules and the reduced PuO_2(110) surface using ab initio molecular dynamics(AIMD) simulations in combination with density functional theory(DFT) + U calculations. We find a dominating dissociation preference of water molecules for the vacancy defect sites on the PuO_2(110) surface, irrespective of the water or vacancy coverage. Due to hybridizations between the frontier orbitals of water molecule and the electronic states of the vacancy vicinity, partial water dissociation at the vacancy sites is exothermic and barrierless. The dissociation product, an OH group, further hydrogenates the PuO_2(110) surface by occupying the vacancy site.We also observe surface vacancy diffusion induced by the interactions between the water molecules and the surface oxygen atom in the proximity of the defect sites.     

Simulation of Unidirectional Ion Ejection in an Asymmetric Half-Round Rod Electrode Linear Ion Trap Mass Analyzer

An asymmetric trapping field was generated from an asymmetric half-round rod electrode linear ion trap (A-HreLIT), and its performance of unidirectional ion ejection was studied. Two different asymmetric structures of A-HreLITs were constructed, one rotating y electrode pairs toward an x electrode with an angle θ, and the other stretching one x electrode with a distance α. The center of trapping field was displaced away from the geometrical center of the ion trap, defined to be the midpoint along the axis of y between x electrodes, which leads to unidirectional ion ejection through one x electrode. Computer simulations were used to investigate the relationship between asymmetric geometric parameter of θ (or α) and analytical performance. Both structures could result in similar asymmetric trapping fields, which mainly composed of dipole, quadrupole, and hexapole fields. The dipole and hexapole fields were approximately proportional to the asymmetric geometric parameter of rotation angle θ (or stretch distance α). In simulation, ion trajectories and ion kinetic energy were calculated. For ions with m/z 609 Th, the simulation results showed that mass resolution of over 2400 (FWHM) and ion unidirectional ejection efficiency of nearly 90% were achieved in an optimized A-HreLIT. Ion detection efficiency of A-HreLIT could be improved significantly with only one ion detector, while maintaining a considerable mass resolution. Furthermore, the A-HreLIT could be driven by a traditional balanced RF power supply. These advantages make A-HreLIT suitable for developing miniaturized mass spectrometer with high performance.

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Large eddy simulation of compressible turbulent channel flow with spanwise wall oscillation

The influences of the modification of turbulent coherent structures on temperature field and heat transfer in turbulent channel flow are studied using large eddy simulation (LES) of compressible turbulent channel flows with spanwise wall oscillation (SWO). The reliability of the LES on such problems is proved by the comparisons of the drag reduction data with those of other researches. The high consistency of coherent velocity structures and temperature structures is found based on the analyses of the turbulent flow field. When the coherent velocity structures are suppressed, the transportations of momentum and heat are reduced simultaneously, demonstrating the same trend. This shows that the turbulent coherent structures have the same effects on the transportations of momentum and heat. The averaged wall heat flux can be reduced with appropriate oscillating parameters. Supported by the Key Subjects of National Natural Science Foundation of China (Grant No. 10732090), the National Natural Science Foundation of China (Grant No. 50476004), and the 111 Project (Grant No. B08009)