arXiv subjects

Wenqing Wang

Publications and source records attributed to Wenqing Wang.

41 records · Page 3Linked to original sources

arXiv2018

Morley-Wang-Xu element methods with penalty for a fourth order elliptic singular perturbation problem

Two Morley-Wang-Xu element methods with penalty for the fourth order elliptic singular perturbation problem are proposed in this paper, including the interior penalty Morley-Wang-Xu element method and the super penalty Morley-Wang-Xu element method. The key idea in designing these two methods is combining the Morley-Wang-Xu element and penalty formulation for the Laplace operator. Robust a priori error estimates are derived under minimal regularity assumptions on the exact solution by means of some established a posteriori error estimates. Finally, we present some numerical results to demonstrate the theoretical estimates.

math.NA↗

arXiv2002

Temperature dependence of optical rotation study on parity-violating phase transition of D-, L-, and DL-alanine

Chiral molecules are characterized by a specific optical rotation angle. An experimental method was presented to dissect the temperature dependence of the optical rotation angle with the molecular chirality of D-alanine, L-alanine and DL-alanine crystals. Salam hypothesis predicted that quantum mechanical cooperative and condensation phenomena may give rise to a second order phase transition below a critical temperature linking the transformation of D-amino acids to L-amino acids due to parity-violating energy difference. The temperature- dependent measurement of the optical rotation angle of D-, L- and DL-alanine crystals provided the direct evidence of the phase transition, but denied the configuration change from D-alanine to L-alanine. New views on Salam hypothesis are presented to demonstrate its importance in the application of low temperature enantiomeric separation and the origin of biochirality.

physics.bio-ph↗

arXiv2002

A Review of Salam Phase Transition in Protein Amino Acids: Implication for Biomolecular Homochirality

The origin of chirality, closely related to the evolution of life on the earth, has long been debated. In 1991, Abdus Salam suggested a novel approach to achieve biomolecular homochirality by a phase transition. In his subsequent publication, he predicted that this phase transition could eventually change D-amino acids to L-amino acids as C -H bond would break and H atom became a superconductive atom. Since many experiments denied the configuration change in amino acids, Salam hypothesis aroused suspicion. This paper is aimed to provide direct experimental evidence of a phase transition in alanine, valine single crystals but deny the configuration change of D- to L- enantiomers. New views on Salam phase transition are presented to revalidate its great importance in the origin of homochirality.

physics.bio-ph↗

arXiv2002

Low Temperature Dependence in 1H CRAMPS & 13C CP/MAS ssNMR Spectra of Alanine Enantiomers

1H RAMPS solid state NMR and 13C CP/MAS spectra of D- and L- alanine crystals were measured at temperature ranging from 220K to 295K. Some major points are as follows: (1)alpha-H and protons in the methyl group showed a spin-spin coupling effect as temperature went down in the 1H- MAS spectra of D-alanine. (2) In the 1H CRAMPS spectra, peak widths of alpha-H and beta-H showed a different trend between alanine enantiomers when temperature varied.(3) The dynamic behavior of 13C spectra showed an obvious change around 250K, which was supposed as a phase transition in alanine crystal. In the discussion section, we give these experimental phenomena a possible explanation related to chirality.

physics.bio-ph↗

arXiv2002

Search for the Parity-Violating Effects between D- and L-alanine

The contribution of parity-violating effects to the phase transition of the D-/L-alanine crystals was confirmed by 1H CRAMPS solid state NMR, DC-magnetic susceptibilities and ultrasonic measurements. It was found that the spin relaxation mechanism of alpha-H nucleus of D-alanine molecule is different from L-alanine and the effect is stronger than that of L-alanine. In addition, D-alanine undergoes a magnetic phase transition at a field of 1.0T, which is confirmed by a peak-form ultrasonic attenuation curve. DC-magnetic susceptibilities measurements of L-alanine also indicate abnormal magnetic properties, which is accompanied by a step-form ultrasonic attenuation jump and its mechanism seems different from that of D-alanine. The phase transition is considered to act as a cooperating amplification mechanism of the P-odd effects at the molecular level.

physics.chem-ph↗