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11.
The mechanism of decomposition of dialkylamino diazeniumdiolate salts, R(2)N[NONO](-)M(+), to form nitric oxide, NO, was explored using theoretical methods. B3LYP/6-311+G(d) density functional theory calculations gave the optimized geometries, and energetics were further evaluated with the high accuracy CBS-QB3 method, when feasible. Relative pK(a) values were estimated using the PCM model for aqueous solvation. The terminal oxygen is the most basic site, followed closely by the internal oxygen. Protonation of these sites does not lead to decomposition. However, protonation of the weakly basic amino nitrogen leads to very rapid decomposition and NO generation. 相似文献
12.
We theoretically explore the transfer of vortex states between atomic Bose-Einstein condensates and optical pulses using ultraslow and stopped light techniques. We find shining a coupling laser on a rotating two-component ground state condensate with a vortex lattice generates a probe laser field with optical vortices. We also find that optical vortex states can be robustly stored in the atomic superfluids for times, in Rb-87 condensates, limited only by the ground state coherence time. 相似文献
13.
Peter D. Battle Siân E. Dutton Peter A. van Daesdonk 《Journal of solid state chemistry》2010,183(7):1620-1624
Polycrystalline samples of La18Li8Rh4MO39 (M=Ti, Mn, Ru) have been prepared by a solid-state method and studied by neutron powder diffraction. They are isostructural with La18Li8Rh5O39 and adopt the cubic space group with a ∼12.22 Å. Their structure consists of a La-O framework containing intersecting channels that run along 〈111〉. These channels are occupied by chains made up of alternating, face-sharing trigonal-prismatic and octahedral coordination polyhedra; there are two crystallographically distinct types of octahedral site. The prisms are occupied by Li and the transition metals are disordered over the two octahedral sites. 相似文献
14.
The behavior of supersonic mixing layers under three conditions has been examined by schlieren photography and laser Doppler velocimetry. In the schlieren photographs, some large-scale, repetitive patterns were observed within the mixing layer; however, these structures do not appear to dominate the mixing layer character under the present flow conditions. It was found that higher levels of secondary freestream turbulence did not increase the peak turbulence intensity observed within the mixing layer, but slightly increased the growth rate. Higher levels of freestream turbulence also reduced the axial distance required for development of the mean velocity. At higher convective Mach numbers, the mixing layer growth rate was found to be smaller than that of an incompressible mixing layer at the same velocity and freestream density ratio. The increase in convective Mach number also caused a decrease in the turbulence intensity (
u/U).List of symbols
a
speed of sound
-
b
total mixing layer thickness between U
1 – 0.1 U and U
2 + 0.1 U
-
f
normalized third moment of u-velocity, f u3/(U)3
-
g
normalized triple product of u2
, g u2/(U)3
-
h
normalized triple product of u
2, h u
2/(U)3
-
l
u
axial distance for similarity in the mean velocity
-
l
u
axial distance for similarity in the turbulence intensity
-
M
Mach number
-
M
c
convective Mach number (for
1 =
2), M
c (U
1 – U
2)/(a
1 + a
2)
-
P
static pressure
-
r
freestream velocity ratio, r U
2/U
1
-
Re
unit Reynolds number, Re U/
-
s
freestream density ratio, s 2/1
-
T
t
total temperature
-
u
instantaneous streamwise velocity
-
u
deviation of u-velocity, uu – U
-
U
local mean streamwise velocity
-
U
1
primary freestream velocity
-
U
2
secondary freestream velocity
-
average of freestream velocities, (U
1 + U
2)/2
-
U
freestream velocity difference, U U
1 – U
2
-
instantaneous transverse velocity
-
v
deviation of -velocity, – V
-
V
local mean transverse velocity
-
x
streamwise coordinate
-
y
transverse coordinate
-
y
0
transverse location of the mixing layer centerline
-
ensemble average
-
ratio of specific heats
-
boundary layer thickness (y-location at 99.5% of free-stream velocity)
-
similarity coordinate, (y – y
0)/b
-
compressible boundary layer momentum thickness
-
viscosity
-
density
-
standard deviation
-
dimensionless velocity, (U – U
2)/U
- 1
primary stream
- 2
secondary stream
A version of this paper was presented at the 11th Symposium on Turbulence, October 17–19, 1988, University of Missouri-Rolla 相似文献
15.
Let G=(V,E) be a graph and S⊆V. The set S is a secure set if ∀X⊆S,|N[X]∩S|≥|N[X]−S|, and S is a global secure set if S is a secure set and a dominating set. The cardinality of a minimum global secure set of G is the global security number of G, denoted γs(G). The sets studied in this paper are different from secure dominating sets studied in Cockayne et al. (2003) [3], Grobler and Mynhardt (2009) [8], or Klostermeyer and Mynhardt (2008) [13], which are also denoted by γs.In this paper, we provide results on the global security numbers of paths, cycles and their Cartesian products. 相似文献
16.
Stahl's concept of k-tuple coloring the nodes of a graph is extended to specify that adjacent nodes must have i colors in common. Complete results for a minimum such coloring are obtained for bipartite graphs and odd cycles. Partial results are shown for complete graphs. 相似文献
17.
G. G. S. Dutton E. H. Merrifield C. Laffite F. Pratviel-Sosa R. Wylde 《Magnetic resonance in chemistry : MRC》1982,20(3):154-158
1H and 13C NMR chemical shifts are reported for several rhamnobioses and their acetylated derivatives. The effect of substitution on the rhamnose unit has been determined with respect to the anomeric carbons and linked carbons. These effects have been rationalized and have allowed the assignment of the structure of xanthorhamnin. 相似文献
18.
Characterization of competition graphs for arbitrary and acyclic directed graphs are presented. 相似文献
19.
Two common invariants of a graph G are its node clique cover number, θ0(G), and its edge clique cover number, θ1(G). We present in this work a characterization of those graphs for which they and their complements, , have θ0(G)=θ1(G) and θ0()=θ1(). Graphs satis ying these conditions are shown to constitute a subset of those graphs which we term C-graphs. 相似文献
20.
Aldous DJ Batsanov AS Yufit DS Dalençon AJ Dutton WM Steel PG 《Organic & biomolecular chemistry》2006,4(15):2912-2927
Flash vacuum pyrrolysis of vinyl epoxides provides cis-dihydrofuran carboxylic esters in good yields and diastereoselectivities, which, on base-promoted epimerisation afford the complementary trans series. The compounds provide a viable template for a Lewis acid promoted cyclisation to provide the 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane core found in the furofuran series of natural lignans. This strategy is stereodivergent and can be controlled to provide the exo-exo, exo-endo or endo-endo stereochemistries. The approach has been exemplified in syntheses of the sesamyl furofurans (+/-)-epiasarinin and (+/-)-asarinin. 相似文献