In this paper, Let R is
a ring, G be a finite
group of ring automorphisms of R. R*G denote the skew group ring of R under G. We
investigate the right p.q.-Baer property of skew group rings under finite group
action, Assume that R is
a semiprime ring with a finite group G of X-outer ring automorphisms of R, then 1) R*G is p.q.-Baer if and only if R is G-p.q.-Baer; 2) if R is
p.q.-Baer, then R*G is p.q.-Baer.
calculations of three geometry conformation
for tetrahydrofuran (THF, C4H8O) using density functional theory lead to the energy level sequence E(C1) < E(Cs) < E(C2v), where, both the
geometry symmetry C2v and Cs are probably a transition structure. The C1 symmetry is the equilibrium conformation, for its energy is the
lowest one and it is only possible without the negative harmonic
frequency. In C1 conformation,
the 4 of carbon atoms C and oxygen atom O constitute a curved surface or
the helix surface. The tetrahydrofuran molecule can be
as a simple prototype of deoxyribose and has been reviving a quite deal of
interest in radiation damage research. It is well known that the sugar ring
of deoxyribose is considered as a plane in most of the references. If the equilibrium conformation of THF is C1 symmetry with the helix surface, and for the same reason, the sugar ring of deoxyribose would
be also the helix surface; this probably causes the double helix of DNA.
It is hardly believed that the sugar ring
is a plane in deoxyribose.