14,249 research outputs found
Quantum Non-Demolition Test of Bipartite Complementarity
We present a quantum circuit that implements a non-demolition measurement of
complementary single- and bi-partite properties of a two-qubit system:
entanglement and single-partite visibility and predictability. The system must
be in a pure state with real coefficients in the computational basis, which
allows a direct operational interpretation of those properties. The circuit can
be realized in many systems of interest to quantum information.Comment: 4 pages, 2 figure
Experimental Observation of Environment-induced Sudden Death of Entanglement
We demonstrate the difference between local, single-particle dynamics and
global dynamics of entangled quantum systems coupled to independent
environments. Using an all-optical experimental setup, we show that, while the
environment-induced decay of each system is asymptotic, quantum entanglement
may suddenly disappear. This "sudden death" constitutes yet another distinct
and counter-intuitive trait of entanglement.Comment: 4 pages, 4 figure
A model for structural defects in nanomagnets
A model for describing structural pointlike defects in nanoscaled
ferromagnetic materials is presented. Its details are explicitly developed
whenever interacting with a vortex-like state comprised in a thin nanodisk.
Among others, our model yields results for the vortex equilibrium position
under the influence of several defects along with an external magnetic field in
good qualitative agreement with experiments. We also discuss how such defects
may affect the vortex motion, like its gyrotropic oscillation and dynamical
polarization reversal.Comment: 8 pages, resubmitted to Journal of Applied Physic
Impact of biofilms in simulated drinking water and urban heat supply systems
Biofouling and biocorrosion were studied in drinking water
and heating water systems by forming biofilms on steel and on
polymethylmetacrylate. In the drinking water system, biofilm development
was more significant on corroded surfaces, suggesting that in these conditions
they were largely protected from disinfection, probably because of sheltering
and chlorine demand by corrosion products. In the urban heat supply system,
results suggest a higher biofilm activity at lower pH. Sulphate-reducing
bacteria were detected in the urban heating biofilms, but little corrosion
was observed on steel coupons. Results indicate that surface and bulk
medium properties, as well as bacterial diversity are determinant parameters
when studying biofouling and biocorrosion.Cirius – Danish Centre for
International Cooperation and Mobility in Education and Trainin
The influence of surface material on the development of Desulfovibrio desulfuricans biofilms
Sulphate reducing bacteria have an important role in the sulphur cycle, and therefore in wastewater treatment
systems. They are able to form biofilms on metallic surfaces, leading to fouling and corrosion problems.
Additionally, hydrogen sulphide that is a product of their metabolism can cause serious health risks. In this study,
sulphate reducing bacteria (SRB) biofilms were developed on stainless steel 304 and on polycarbonate in order to
evaluate surface effect on biofilm formation.
Results showed that the biofilm formed on stainless steel presented higher metabolic activity, confirmed by lactate
and sulfate removals. Metal elements present in stainless steel may affect SRB activity. This can be the case of
nickel that represents around 8% of stainless steel 304. Studies performed with suspended cultures of Desulfovibrio
desulfuricans also showed that the presence of nickel in the media had a positive impact on bacterial activity
The influence of nickel on the adhesion ability of Desulfovibrio desulfuricans
The build-up of biofilms on metals surfaces may lead to severe corrosion, especially in the presence of sulphate-reducing bacteria (SRB). To prevent the deterioration of material caused by biofilms it is necessary to understand the processes governing biofilm development including mechanisms of cell adhesion. Additionally, corrosion of metallic surfaces due to bacteria may lead to the dissolution of metallic elements that may
further affect adhesion and biofilm development. A study was carried out to evaluate how the presence of nickel in the substrata affects the adhesion
ability of Desulfovibrio desulfuricans. The substrata tested were stainless steel 304 (SS), metallic nickel (Ni) and polymethylmetacrylate (PMMA), a non-metallic material used as control. The influence of nickel on SRB growth and its relation to adhesion was also checked. A statistically
significant difference in the number of adhered cells to the materials tested was detected, with higher bacterial number on nickel, followed by SS and finally by PMMA. The higher number of SRB adhered to steel compared with PMMA may be explained by differences in hydrophobicity, in
roughness and in the electron-acceptor character of the substrata. Additionally, bacterial growth was found to be positively affected by the presence of nickel as revealed by a significant increase in the specific growth rate of SRB in the presence of increased nickel concentrations.Programme Praxis XXI
The effect of dissolved stainless steel alloy elements on the activity and growth of SRB
Sulphate reducing bacteria have an important role in the sulphur cycle, and therefore in
wastewater treatment systems. They are able to form biofilms on metallic surfaces, leading to
fouling and corrosion problems. These bacteria are among the micro-organisms most
frequently implicated in microbial corrosion of iron and ferrous alloys.
Alloying elements added to steels for the improvement of their corrosion resistance such as
molybdenum and nickel can be dissolved in bulk liquid during the corrosion processes and
therefore available to the micro-organisms. That may affect bacterial metabolism and adhesion.
In this study, suspended cultures of sulphate reducing bacteria (SRB) were subjected to several
nickel concentrations in order to evaluate the effect of the dissolved metal on bacterial
metabolism. Simultaneously, SRB biofilms were developed on stainless steel 304 and on polymethylmethacrylate
(PMMA) in order to study surface effect on biofilm formation. Results
showed that nickel (Ni) in all tested concentrations between 0.006 and 5 mg/L had a positive
effect on the growth of Desuljovibrio desulfuricans. Additionally, biofilms formed on stainless
steel presented higher metabolic activity, confirmed by sulphate removal and acetate
concentration in the effluent stream. Metal elements present in stainless steel may affect SRB
activity. This can be the case of nickel that represents around 8% of stainless steel 304 and that
had a positive impact on suspended SRB cultures, under the tested concentrations
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