820 research outputs found
2-(4-Chlorophenyl)naphtho[1,8-de][1,3,2]diazaborinane
The title compound, C16H12BClN2, is one in a series of diazaborinanes, derived from 1,8-diaminonaphthalene, featuring substitution at the 1, 2 and 3 positions in the nitrogen-boron heterocycle. The structure deviates from planarity, the torsion angle subtended by the p-chlorophenyl ring relative to the nitrogen–boron heterocycle being −44-.3(3)°. The molecules form infinite chains with strong interactions between the vacant pz orbital of the B atom and the π-system of an adjacent molecule. The distance between the B atom and the 10-atom centroid of an adjacent naphthalene ring is 3.381 (4) Å. One N-H H atom is weakly hydrogen bonded to the Cl atom of an adjacent molecule. This combination of intermolecular interactions leads to the formation of an infinite two-dimensional network perpendicular to the c axis
2-Phenylnaphtho[1,8-de][1,3,2]diazaborinane
The title compound, C16H13BN2, is one compound in a series of diazaborinanes featuring substitution at the 1, 2 and 3 positions in the nitrogen–boron heterocycle. The title compound is slightly distorted from planarity, with a dihedral angle of 9.0 (5)° between the mean planes of the naphthalene system and the benzene ring. The m-carbon atom of the benzene ring exhibits the greatest deviation of 0.164 (2) Å from the 19-atom mean plane defined by all non-H atoms. The two N—B—C—C torsion angles are 6.0 (3) and 5.6 (3)°. In the crystal, molecules are linked by π–π interactions into columns, with a distance of 3.92 (3) Å between the naphthalene ring centroids. Adjacent π-stacked columns, co-linear with the b-axis, are linked by C—H⋯π interactions
2-[4-(Methylsulfanyl)phenyl]naphtho[1,8-de][1,3,2]diazaborinane
The title compound, C17H15BN2S, is one member in a series of diazaborinanes featuring substitution at the 1-, 2- and 3-positions in the nitrogen–boron heterocycle. The dihedral angle between the mean planes of the naphthalene and phenyl ring systems is 19.86 (6)°. In the crystal structure, two C—H⋯π interactions link the molecules into sheets which lie parallel to the bc plane. There is a π–π interaction between each pair of centrosymmetrically related sheets [centroid–centroid distance = 3.5922 (8) Å]
Flow cytometric S-phase fraction in soft-tissue sarcoma: prognostic importance analysed in 160 patients.
We could determine the S-phase fraction (SPF) by flow cytometric DNA analysis of paraffin archival material in 160 of 260 patients with soft-tissue sarcoma of extremity and trunk wall. The prognostic value of SPF was compared with other clinicopathological factors. The median follow-up time was 16 (6-31) years. In a univariate analysis, deep tumour location, increasing tumour size and histological malignancy grade, microscopic tumour necrosis, vascular invasion, DNA non-diploidy and high SPF (>3.0%) were associated with poor metastasis-free survival. In a multivariate analysis, microscopic tumour necrosis and high SPF were independently prognostic for metastasis. Used in combination with tumour size, microscopic tumour necrosis and vascular invasion, SPF could identify a group of patients with a 5-year metastasis-free survival rate of 0.97. This group constituted one-quarter of all patients. Patients with low SPF who did recur had a prolonged clinical course both as regards metastases and local recurrence. We conclude that SPF is a valuable adjunct in prognostication in soft-tissue sarcoma
On thermalization of magnetic nano-arrays at fabrication
We propose a model to predict and control the statistical ensemble of
magnetic degrees of freedom in Artificial Spin Ice (ASI) during thermalized
adiabatic growth. We predict that as-grown arrays are controlled by the
temperature at fabrication and by their lattice constant, and that they can be
described by an effective temperature. If the geometry is conducive to a phase
transition, then the lowest temperature phase is accessed in arrays of lattice
constant smaller than a critical value, which depends on the temperature at
deposition. Alternatively, for arrays of equal lattice constant, there is a
temperature threshold at deposition and the lowest temperature phase is
accessed for fabrication temperatures {\it larger rather than smaller} than
this temperature threshold. Finally we show how to define and control the
effective temperature of the as-grown array and how to measure critical
exponents directly. We discuss the role of kinetics at the critical point, and
applications to experiments, in particular to as-grown thermalized square ASI,
and to magnetic monopole crystallization in as-grown honeycomb ASI.Comment: 14 pages, 2 figures. A theoretical approach to experimental results
reported in: Morgan J P, Stein A, Langridge S and Marrows C (2010) Nature
Physics 7 7
Apparent counter-rotation in the torus of NGC 1068: influence of an asymmetric wind
The recent ALMA maps together with observations of HO maser emission seem
to suggest the presence of a counter-rotation in the obscuring torus of NGC
1068. We propose to explain this phenomenon as due to the influence of a wind,
considered as radiation pressure, and the effects of torus orientation. In
order to test this idea: 1. we make -body simulation of a clumpy torus
taking into account mutual forces between particles (clouds); 2. we apply
ray-tracing algorithm with the beams from the central engine to choose the
clouds in the torus throat that can be under direct influence of the accretion
disk emission; 3. we use semi-analytical model to simulate the influence of the
asymmetrical radiation pressure (wind) forced on the clouds in the torus
throat. An axis of such a wind is tilted with respect to the torus symmetry
axis; 4. we orient the torus relative to an observer and again apply
ray-tracing algorithm. In this step the beams go from an observer to the
optically thick clouds that allows us to take into account the mutual
obscuration of clouds; 5. after projecting on the picture plane, we impose a
grid on the resulting cloud distribution and find the mean velocity of clouds
in each cells to mimic the ALMA observational maps. By choosing the parameters
corresponding to NGC 1068 we obtain the model velocity maps that emulate the
effect of an apparent counter-rotation and can explain the discovery made by
ALMA.Comment: 11 pages, 11 figures, Accepted for publication in MNRA
A network model for field and quenched disorder effects in artificial spin ice
We have performed a systematic study of the effects of field strength and
quenched disorder on the driven dynamics of square artificial spin ice. We
construct a network representation of the configurational phase space, where
nodes represent the microscopic configurations and a directed link between node
i and node j means that the field may induce a transition between the
corresponding configurations. In this way, we are able to quantitatively
describe how the field and the disorder affect the connectedness of states and
the reversibility of dynamics. In particular, we have shown that for optimal
field strengths, a substantial fraction of all states can be accessed using
external driving fields, and this fraction is increased by disorder. We discuss
how this relates to control and potential information storage applications for
artificial spin ices
Disorder strength and field-driven ground state domain formation in artificial spin ice: experiment, simulation and theory
Quenched disorder affects how non-equilibrium systems respond to driving. In
the context of artificial spin ice, an athermal system comprised of
geometrically frustrated classical Ising spins with a two-fold degenerate
ground state, we give experimental and numerical evidence of how such disorder
washes out edge effects, and provide an estimate of disorder strength in the
experimental system. We prove analytically that a sequence of applied fields
with fixed amplitude is unable to drive the system to its ground state from a
saturated state. These results should be relevant for other systems where
disorder does not change the nature of the ground state.Comment: The manuscript has been reworked. To be published in Phys. Rev. Let
Plasmonic nickel nanoantennas
7 páginas, 6 figuras.-- El pdf del artículo es la versión post-print.-- et al.The fundamental optical properties of pure nickel nanostructures are studied by far-field extinction spectroscopy and optical near-field microscopy, providing direct experimental evidence of the existence of particle plasmon resonances predicted by theory. Experimental and calculated near-field maps allow for unambiguous identification of dipolar plasmon modes. By comparing calculated near-field and far-field spectra, dramatic shifts are found between the near-field and far-field plasmon resonances, which are much stronger than in gold nanoantennas. Based on a simple damped harmonic oscillator model to describe plasmonic resonances, it is possible to explain these shifts as due to plasmon damping.Supported by the European FP7 project ‘Nanoantenna’ (FP7-HEALTH-F5-2009-241818-NANOANTENNA) and the National Project MAT2009 –08398 from the Spanish Ministerio de Ciencia
e Innovacion. J.A. acknowledges fi nancial help by the Department of Industry of the Basque Government through the ETORTEK program NANOPHOT. P.V. acknowledges funding from the Basque Government under Programs No. PI2009–17 as well as the Spanish Ministry of Science and Education under Project No. MAT2009–07980. Z. P. acknowledges support from Swedish Foundation for
Strategic Research through RMA08–0109 “Functional Electromagnetic Metamaterials” program. J. N. acknowledges funding from the Generalitat de Catalunya and the Spanish Ministry of Science
and Education through No. 2009-SGR-1292 and No. MAT2010–20616-C02 projects. A.D. acknowledges support from the Swedish Research Council.Peer reviewe
Thermoregulatory uncoupling in heart muscle mitochondria: involvement of the ATP/ADP antiporter and uncoupling protein
AbstractPossible involvement of the ATP/ADP antiporter and uncoupling protein (UCP) in thermoregulatory uncoupling of oxidative phosphorylation in heart muscle has been studied. To this end, effects of carboxyatractylate (cAtr) and GDP, specific inhibitors of the antiporter and UCP, on the membrane potential of the oligomycin-treated mitochondria from cold-exposed (6°C, 48 h) and control rats have been measured. It is found that cAtr increases the membrane potential level in both cold-exposed and non-exposed groups, the effect being strongly enhanced by cooling. As for GDP, it is effective only in mitochondria from the cold-exposed rats. In these mitochondria, the coupling effect of GDP is smaller than that of cAtr. CDP, which does not interact with UCP, is without any influence on membrane potential. The cold exposure is found to increase the uncoupling efficiency of added natural (palmitate) or artificial (SF6847) uncouplers, the increase being cAtr- and GDP-sensitive in the case of palmitate. The fatty acid-free bovine serum albumin enhances ΔΨ in both cold-exposed and control groups, the effect being much larger in the former case. It is concluded that in heart muscle mitochondria the ATP/ADP antiporter is responsible for the `mild uncoupling' under normal conditions and for major portion of the thermoregulatory uncoupling in the cold whereas the rest of thermoregulatory uncoupling is served by UCP (presumably by UCP2 since the UCP2 mRNA level is shown to strongly increase in rat heart muscle under the cold exposure conditions used)
- …