620 research outputs found
Different sensing mechanisms in single wire and mat carbon nanotubes chemical sensors
Chemical sensing properties of single wire and mat form sensor structures
fabricated from the same carbon nanotube (CNT) materials have been compared.
Sensing properties of CNT sensors were evaluated upon electrical response in
the presence of five vapours as acetone, acetic acid, ethanol, toluene, and
water. Diverse behaviour of single wire CNT sensors was found, while the mat
structures showed similar response for all the applied vapours. This indicates
that the sensing mechanism of random CNT networks cannot be interpreted as a
simple summation of the constituting individual CNT effects, but is associated
to another robust phenomenon, localized presumably at CNT-CNT junctions, must
be supposed.Comment: 12 pages, 5 figures,Applied Physics A: Materials Science and
Processing 201
A Two-loop Test of Buscher's T-duality I
We study the two loop quantum equivalence of sigma models related by
Buscher's T-duality transformation. The computation of the two loop
perturbative free energy density is performed in the case of a certain
deformation of the SU(2) principal sigma model, and its T-dual, using
dimensional regularization and the geometric sigma model perturbation theory.
We obtain agreement between the free energy density expressions of the two
models.Comment: 28 pp, Latex, references adde
Asymptotic function for multi-growth surfaces using power-law noise
Numerical simulations are used to investigate the multiaffine exponent
and multi-growth exponent of ballistic deposition growth
for noise obeying a power-law distribution. The simulated values of
are compared with the asymptotic function that is
approximated from the power-law behavior of the distribution of height
differences over time. They are in good agreement for large . The simulated
is found in the range . This implies that large rare events tend to break the KPZ
universality scaling-law at higher order .Comment: 5 pages, 4 figures, to be published in Phys. Rev.
Invading interfaces and blocking surfaces in high dimensional disordered systems
We study the high-dimensional properties of an invading front in a disordered
medium with random pinning forces. We concentrate on interfaces described by
bounded slope models belonging to the quenched KPZ universality class. We find
a number of qualitative transitions in the behavior of the invasion process as
dimensionality increases. In low dimensions the system is characterized
by two different roughness exponents, the roughness of individual avalanches
and the overall interface roughness. We use the similarity of the dynamics of
an avalanche with the dynamics of invasion percolation to show that above
avalanches become flat and the invasion is well described as an annealed
process with correlated noise. In fact, for the overall roughness is
the same as the annealed roughness. In very large dimensions, strong
fluctuations begin to dominate the size distribution of avalanches, and this
phenomenon is studied on the Cayley tree, which serves as an infinite
dimensional limit. We present numerical simulations in which we measured the
values of the critical exponents of the depinning transition, both in finite
dimensional lattices with and on the Cayley tree, which support our
qualitative predictions. We find that the critical exponents in are very
close to their values on the Cayley tree, and we conjecture on this basis the
existence of a further dimension, where mean field behavior is obtained.Comment: 12 pages, REVTeX with 2 postscript figure
Crossover of texture and morphology in (Ti1 − xAlx)1 − yYyN alloy films and the pathway of structure evolution
In our earlier published work, we have shown that there is a composition range of the (Ti 1 − x Al x ) 1 − y Y y N alloy
films (0.72 b Ti/Al b 0.88) deposited at oblique vapour beam incidence and 500 °C (corresponding to zone T) in
which mixed cubic TiN (c-TiN) and wurtzite AlN (w-AlN) structures were formed together with an unusual
complex texture. The texture of c-TiN phase changed from 〈001〉 to b111N at a certain thickness forming a definite
crossover. Moreover the c-TiNb111N and the w-AlN〈0001〉 crystals were epitaxially related with axes tilted to the
direction of the vapour beam.
Based on a comprehensive transmission electron microscopy (TEM) and diffraction (XRD and selected area
electron diffraction (SAED)) structure and morphology analysis, we discovered the details of this exotic structure
making it possible to construct the complex pathway of structure evolution including the formation of the w-AlN
phase and the change of the dominating texture of c-TiN phase with thickness in dependence of the Ti/Al ratio
and the deposition parameters. This pathway could be deduced from the fundamental phenomena of structure
formation and may be generalised for multi-component thin film systems. A composition structure zone
model has been also proposed for the (Ti 1 − x Al x ) 1 − y Y y N thin film system in the 0 b x b 1 composition range
Crossover of texture and morphology in (Ti 1 − x Al x ) 1 − y Y y N alloy films and the pathway of structure evolution
In our earlier published work, we have shown that there is a composition range of the (Ti 1 − x Al x ) 1 − y Y y N alloy
films (0.72 b Ti/Al b 0.88) deposited at oblique vapour beam incidence and 500 °C (corresponding to zone T) in
which mixed cubic TiN (c-TiN) and wurtzite AlN (w-AlN) structures were formed together with an unusual
complex texture. The texture of c-TiN phase changed from 〈001〉 to b111N at a certain thickness forming a definite
crossover. Moreover the c-TiNb111N and the w-AlN〈0001〉 crystals were epitaxially related with axes tilted to the
direction of the vapour beam.
Based on a comprehensive transmission electron microscopy (TEM) and diffraction (XRD and selected area
electron diffraction (SAED)) structure and morphology analysis, we discovered the details of this exotic structure
making it possible to construct the complex pathway of structure evolution including the formation of the w-AlN
phase and the change of the dominating texture of c-TiN phase with thickness in dependence of the Ti/Al ratio
and the deposition parameters. This pathway could be deduced from the fundamental phenomena of structure
formation and may be generalised for multi-component thin film systems. A composition structure zone
model has been also proposed for the (Ti 1 − x Al x ) 1 − y Y y N thin film system in the 0 b x b 1 composition range
Modest genetic influence on bronchodilator response: a study in healthy twins.
AIM: To determine the reasons for large standard deviation of bronchodilator response (BDR) and establish whether there is a potential heritable component in healthy subjects. METHODS: 67 monozygotic and 42 dizygotic adult twin pairs were assessed for bronchodilator response (% change in FEV1 after inhaling 400 microg salbutamol). Univariate quantitative genetic modeling was performed. RESULTS: Multiple regression modeling showed a significant association between BDR and sex and baseline FEV1 (P<0.05), while no association was found with smoking habits, body mass index, or age. Within pair correlation in monozygotic twins was modest (0.332), but higher than in dizygotic twins (0.258). Age-, sex-, and baseline FEV1-adjusted genetic effect accounted for 14.9% (95% confidence interval, CI 0%-53.1%) of the variance of BDR, shared environmental effect for 18.4% (95% CI 0%-46.8%), and unshared environmental effect for 66.8% (95% CI 46.8%-88.7%). CONCLUSION: Our twin study showed that individual differences in BDR can be mostly explained by unshared environmental effects. In addition, it is the first study to show low, insignificant hereditary influences, independently from sex, age, and baseline FEV1
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