918 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
Classification of KPZQ and BDP models by multiaffine analysis
We argue differences between the Kardar-Parisi-Zhang with Quenched disorder
(KPZQ) and the Ballistic Deposition with Power-law noise (BDP) models, using
the multiaffine analysis method. The KPZQ and the BDP models show mono-affinity
and multiaffinity, respectively. This difference results from the different
distribution types of neighbor-height differences in growth paths. Exponential
and power-law distributions are observed in the KPZQ and the BDP, respectively.
In addition, we point out the difference of profiles directly, i.e., although
the surface profiles of both models and the growth path of the BDP model are
rough, the growth path of the KPZQ model is smooth.Comment: 11 pages, 6 figure
Identification of key effects causing weak performance of allergen analysis in processed food matrices
The weaker performance of generally used analytical methods for allergen analysis in processed foods can be connected to protein denaturation. To understand the nature of protein denaturation processes, experimental but realistic model matrices (corn starch based mixture, hydrated dough, and heat treated cookies) were developed that contain a defined amount of milk, egg, soy, and wheat proteins individually or in combination. The protein subunit composition was investigated in every processing phase, i.e. after mixing, dough formation, and baking. SDS-PAGE measurements were carried out to monitor the protein distribution of sample food matrices in non-reducing and reducing gels. The results clearly show that the highly decreased protein solubility is caused by denaturation, aggregation, or complex formation, which are the most significant factors in poorer analytical performances. Solubility can only partly be improved with the application of reducing agents or surfactants, and the rate of improvement is depending on the proteins and the matrices
Pipe network model for scaling of dynamic interfaces in porous media
We present a numerical study on the dynamics of imbibition fronts in porous
media using a pipe network model. This model quantitatively reproduces the
anomalous scaling behavior found in imbibition experiments [Phys. Rev. E {\bf
52}, 5166 (1995)]. Using simple scaling arguments, we derive a new identity
among the scaling exponents in agreement with the experimental results.Comment: 13 pages, 3 figures, REVTeX, to appear in Phys. Rev. Let
The cultural and geopolitical dimensions of nation-building in the Ukraine
Ukraine belongs among those young countries where the beginnings of democratisation and nation-building approximately coincided. While the development of nation states in Central Europe was usually preceded by the development of nations, the biggest dilemma in the Ukraine is whether a nation-state programme — parallel to the aim of state-building — is able to bring unfinished nation-building to completion. Ukraine sways between the EU and Russia with enormous amplitude. The alternating orientation between the West and the East can be ascribed to superpower ambitions reaching beyond Ukraine. Eventually, internal and external determinants are intertwined and mutually interact with one another. The aim of the paper is to explain the dilemmas arising from identity problems behind the Ukraine’s internal and external orientation
Directed Surfaces in Disordered Media
The critical exponents for a class of one-dimensional models of interface
depinning in disordered media can be calculated through a mapping onto directed
percolation (DP). In higher dimensions these models give rise to directed
surfaces, which do not belong to the directed percolation universality class.
We formulate a scaling theory of directed surfaces, and calculate critical
exponents numerically, using a cellular automaton that locates the directed
surfaces without making reference to the dynamics of the underlying interface
growth models.Comment: 4 pages, REVTEX, 2 Postscript figures avaliable from [email protected]
Driven interfaces in disordered media: determination of universality classes from experimental data
While there have been important theoretical advances in understanding the
universality classes of interfaces moving in porous media, the developed tools
cannot be directly applied to experiments. Here we introduce a method that can
identify the universality class from snapshots of the interface profile. We
test the method on discrete models whose universality class is well known, and
use it to identify the universality class of interfaces obtained in experiments
on fluid flow in porous media.Comment: 4 pages, 5 figure
Biscale Chaos in Propagating Fronts
The propagating chemical fronts found in cubic autocatalytic
reaction-diffusion processes are studied. Simulations of the reaction-diffusion
equation near to and far from the onset of the front instability are performed
and the structure and dynamics of chemical fronts are studied. Qualitatively
different front dynamics are observed in these two regimes. Close to onset the
front dynamics can be characterized by a single length scale and described by
the Kuramoto-Sivashinsky equation. Far from onset the front dynamics exhibits
two characteristic lengths and cannot be modeled by this amplitude equation. An
amplitude equation is proposed for this biscale chaos. The reduction of the
cubic autocatalysis reaction-diffusion equation to the Kuramoto-Sivashinsky
equation is explicitly carried out. The critical diffusion ratio delta, where
the planar front loses its stability to transverse perturbations, is determined
and found to be delta=2.300.Comment: Typeset using RevTeX, fig.1 and fig.4 are not available, mpeg
simulations are at
http://www.chem.utoronto.ca/staff/REK/Videos/front/front.htm
Effect of a columnar defect on the shape of slow-combustion fronts
We report experimental results for the behavior of slow-combustion fronts in
the presence of a columnar defect with excess or reduced driving, and compare
them with those of mean-field theory. We also compare them with simulation
results for an analogous problem of driven flow of particles with hard-core
repulsion (ASEP) and a single defect bond with a different hopping probability.
The difference in the shape of the front profiles for excess vs. reduced
driving in the defect, clearly demonstrates the existence of a KPZ-type of
nonlinear term in the effective evolution equation for the slow-combustion
fronts. We also find that slow-combustion fronts display a faceted form for
large enough excess driving, and that there is a corresponding increase then in
the average front speed. This increase in the average front speed disappears at
a non-zero excess driving in agreement with the simulated behavior of the ASEP
model.Comment: 7 pages, 7 figure
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