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1.
Ab initio SCF computations on the intrinsic preferences of the H+, CH
3
+
and C2H
5
+
cations towards the two principal sites of protonation or alkylation on cytosine, N3 or O2, show that this preference undergoes a continuous modification with the increase in size and complexity of the cation. N3 is the preferred site of fixation of H+, O2 the preferred site of C2H
5
+
, while CH
3
+
has no marked preference. The exchange repulsion term of the binding energy appears responsible for the preference of C2H
5
+
for O2.This work was supported by the Ligue Francaise contre le Cancer and the National Foundation for Cancer Research (USA) 相似文献
2.
《Composite Interfaces》2013,20(2-3):113-126
Polyamide66/polypropylene (PA66/PP) blend, graphite (Gr)-filled PA66/PP composite and nanoclay (NC)-filled PA66/PP nanocomposites were prepared by twin screw extrusion and injection molding. Three-body abrasive wear behaviour of the injection moulded composites was carried out using a rubber wheel abrasion wear tester. In this study, angular silica sand and quartz particles of size ranging from 200 to 250 μm were used as dry and loose abrasives. The tests were carried out for 150, 300, 450 and 600 m abrading distances at a constant load of 36 N. It was observed that inclusion of particulate fillers in PA66/PP have significant influence on wear under varied abrading distances for different abrasive particles. Further, it was found that NC-filled PA66/PP nanocomposite exhibited lower wear rate compared to Gr filled ones for different abrasive particles. In addition, the worn surfaces of the samples were examined by scanning electron microscopy (SEM) and the morphology was also discussed. 相似文献
3.
Radul has recently introduced a map from the Lie algebra of differential operators on the circle of W
n
. In this Letter, we extend this map to W
KP
(q)
, a recently introduced one-parameter deformation of WKP - the second Hamiltonian structure of the KP hierarchy. We use this to give a short proof that W is the algebra of additional symmetries of the KP equation. 相似文献
4.
The infinitely many symmetries with arbitrary functions of timet for the potential modified Kadomtsev-Petviashvilli equation are obtained by using a simple direct method. These symmetries constitute a generalization of the well-knownW
algebra. 相似文献
5.
The major contributions of Richard H. Dalitz to hypernuclear physics, since his first paper in 1955 to his last one in 2005 covering a span of 50 years during which he founded and led the theoretical study of hypernuclei, are reviewed from a personal perspective. Topical remarks on the search for quasi-bound -nuclear states and on kaon condensation are made. 相似文献
6.
M. Laoues 《Letters in Mathematical Physics》1991,23(4):325-331
We consider the real vector space structure of the algebra of linear endomorphisms of a finite-dimensional real Clifford algebra (2, 4, 5, 6, 7, 8). A basis of that space is constructed in terms of the operators M
eI, eJ
defined by xe
I
· x · e
J
, where the e
I
are the generators of the Clifford algebra and I is a multi-index (3, 7).In particular, it is shown that the family (M
eI, eJ
) is exactly a basis in the even case. 相似文献
7.
8.
A. Alvarez F. R. Romero J. F.R. Archilla J. Cuevas P. V. Larsen 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(1):119-130
We study the dynamics of moving discrete breathers in an interfaced piecewise DNA molecule.
This is a DNA chain in which all the base pairs are identical and
there exists an interface such that the base pairs dipole moments at each side are oriented in opposite
directions.
The Hamiltonian of the Peyrard-Bishop model is augmented with a
term that includes the dipole-dipole coupling between base pairs.
Numerical simulations show the existence of two dynamical regimes.
If the translational kinetic energy of a moving breather launched
towards the interface is below a critical value, it is trapped in
a region around the interface collecting vibrational energy. For
an energy larger than the critical value, the breather is
transmitted and continues travelling along the double strand with
lower velocity. Reflection phenomena never occur.
The same study has been carried out when a single dipole is oriented
in opposite direction to the other ones.
When moving breathers collide
with the single inverted dipole, the same effects appear. These
results emphasize the importance of this simple type of local
inhomogeneity as it creates a mechanism for the trapping of
energy.
Finally, the simulations show that, under favorable conditions,
several launched moving breathers can be trapped successively at the interface
region producing an accumulation of vibrational energy. Moreover,
an additional colliding moving breather can produce a saturation
of energy and a moving breather with all the accumulated energy
is transmitted to the chain. 相似文献
9.
In [L. Lebtahi, Lie algebra on the transverse bundle of a decreasing family of foliations, J. Geom. Phys. 60 (2010), 122–133], we defined the transverse bundle Vk to a decreasing family of k foliations Fi on a manifold M. We have shown that there exists a (1,1) tensor J of Vk such that Jk≠0, Jk+1=0 and we defined by LJ(Vk) the Lie Algebra of vector fields X on Vk such that, for each vector field Y on Vk, [X,JY]=J[X,Y]. 相似文献
10.
This paper reports the development of a facile and effective approach, based on the use of Zr-based metal-organic frameworks (UiO-66) sensor with micropores geometry, shape and particle morphology for the visual detection and removal of ultra-traces of some toxic metal ions such as Bi(III), Zn(II), Pb(II), Hg(II) and Cd(II). UiO-66 was used as selective carriers for accommodating hydrophobic chromophore probes such as dithizone (DZ) without coupling agent for sensitive and selective discrimination of trace level of toxic analytes. The developed UiO-66 sensor was utilized for the detection of ultra-traces of some toxic metal ions with the naked eye. The new sensor displays high sensitivity and selectivity of a wide range of detectable metals analytes up to 10−10 mol dm−3 in solution, in a rapid analyte uptake response (seconds). The developed sensor is stable, cost effective, easy to prepare, and would be useful for rapid detection and removal of ultra-traces of toxic metal ions in water samples. 相似文献