169 research outputs found
Evaluation of the tolerability of the Salmonella Typhimurium live vaccine Salmoporc® for oral administration in three day old piglets
Vaccination against Salmonella is a measure to reduce salmonella disease in pigs. In this study a S. Typhimurium live vaccine (Salmoporc®, lmpfstoffwerk Dessau-Tornau, Rosslau, Germany) was applied to 3 day old conventional piglets in order to investigate safety and persistence of the vaccine strain in different tissues. The results indicate that an early vaccination against Salmonella shall be deemed to be safe
MID-IR LED-based, Photoacoustic CO2 Sensor
AbstractThe technology used to implement CO2 sensors depends on the requirements in terms of sensitivity, price and robustness. The most common technology for highly sensitive tasks are based on tunable diode laser spectroscopy, while so-called non-dispersive infrared (NDIR) photometers [2] are used in less demanding scenarios such as control air conditioning systems. Most NDIR systems use thermal emitters as light source which are readily available at low cost but require compensation for cross-sensitivities toward other gas species. The detector technology employed in these systems ranges from photodiodes to thermopiles and pyroelectric detectors, all of which require the use of spectral filters to avoid cross sensitivities. Here we present a low-cost photoacoustic-based detector comprised of a microphone in a hermetically sealed chamber filled with CO2. To excite sound waves a MID-IR LED emitting radiation in the strong CO2 absorption region around 4.2ÎĽm is used for the first time
A trapped single ion inside a Bose-Einstein condensate
Improved control of the motional and internal quantum states of ultracold
neutral atoms and ions has opened intriguing possibilities for quantum
simulation and quantum computation. Many-body effects have been explored with
hundreds of thousands of quantum-degenerate neutral atoms and coherent
light-matter interfaces have been built. Systems of single or a few trapped
ions have been used to demonstrate universal quantum computing algorithms and
to detect variations of fundamental constants in precision atomic clocks. Until
now, atomic quantum gases and single trapped ions have been treated separately
in experiments. Here we investigate whether they can be advantageously combined
into one hybrid system, by exploring the immersion of a single trapped ion into
a Bose-Einstein condensate of neutral atoms. We demonstrate independent control
over the two components within the hybrid system, study the fundamental
interaction processes and observe sympathetic cooling of the single ion by the
condensate. Our experiment calls for further research into the possibility of
using this technique for the continuous cooling of quantum computers. We also
anticipate that it will lead to explorations of entanglement in hybrid quantum
systems and to fundamental studies of the decoherence of a single, locally
controlled impurity particle coupled to a quantum environment
Context-Dependent Behavior of the Enterocin Iterative Polyketide Synthase A New Model for Ketoreduction
AbstractHeterologous expression and mutagenesis of the enterocin type II polyketide synthase (PKS) system suggest for the first time that the association of an extended set of proteins and substrates is needed for the effective production of the enterocin-wailupemycin polyketides. In the absence of its endogenous ketoreductase (KR) EncD in either the enterocin producer “Streptomyces maritimus” or the engineered host S. lividans K4-114, the enterocin minimal PKS is unable to produce benzoate-primed polyketides, even when complemented with the homologous actinorhodin KR ActIII or with EncD active site mutants. These data suggest that the enterocin PKS requires EncD to serve a catalytic and not just a structural role in the functional PKS enzyme complex. This strongly implies that EncD reduces the polyketide chain during elongation rather than after its complete assembly, as suggested for most type II PKSs
Gas sensors for climate research
The availability of datasets providing information on the spatial and
temporal evolution of greenhouse gas concentrations is of high relevance for
the development of reliable climate simulations. However, current gas
detection technologies do not allow for obtaining high-quality data at
intermediate spatial scales with high temporal resolution. In this regard the
deployment of a wireless gas sensor network equipped with in situ gas
analysers may be a suitable approach. Here we present a novel, non-dispersive
infrared absorption spectroscopy (NDIR) device that can possibly act as a
central building block of a sensor node to provide high-quality data of
carbon dioxide (CO2) concentrations under field conditions at a
high measurement rate. Employing a gas-based, photoacoustic detector we
demonstrate that miniaturized, low-cost, and low-power consuming
CO2 sensors may be built. The performance is equal to that of
standard NDIR devices but at a much reduced optical path length. Because of
the spectral properties of the photoacoustic detector, no cross-sensitivities
to humidity exist.</p
Food suspensions study with SR microtomography
The incorporation of a small amount of secondary immiscible liquid to suspensions can lead to a shift from a fluid-like structure to a paste-like structure. This is ascribed to the higher attraction of the secondary liquid to the particles, in comparison to the continuous phase. However, visual observations on the micro-scale during both long and short term time-scales, dependant on the type of secondary immiscible liquid used are yet to be reported. In the current study, the movement of various secondary immiscible liquids (water, sucrose solutions, saturated sucrose solution and glycerol) when added to a model food suspension (sucrose particles in sunflower oil) was investigated. Dynamic X-ray computed tomography was used, as a non-invasive approach, to study the mass transfer on the micro-scale and to observe the bulk movement of sucrose within the suspension. It was found that the affinity of the secondary liquid in dissolving sucrose was the primary contributor to the secondary liquid movement, with density/gravitational effects playing a minimal role
Fast cavity-enhanced atom detection with low noise and high fidelity
Cavity quantum electrodynamics describes the fundamental interactions between
light and matter, and how they can be controlled by shaping the local
environment. For example, optical microcavities allow high-efficiency detection
and manipulation of single atoms. In this regime fluctuations of atom number
are on the order of the mean number, which can lead to signal fluctuations in
excess of the noise on the incident probe field. Conversely, we demonstrate
that nonlinearities and multi-atom statistics can together serve to suppress
the effects of atomic fluctuations when making local density measurements on
clouds of cold atoms. We measure atom densities below 1 per cavity mode volume
near the photon shot-noise limit. This is in direct contrast to previous
experiments where fluctuations in atom number contribute significantly to the
noise. Atom detection is shown to be fast and efficient, reaching fidelities in
excess of 97% after 10 us and 99.9% after 30 us.Comment: 7 pages, 4 figures, 1 table; extensive changes to format and
discussion according to referee comments; published in Nature Communications
with open acces
Quantum flutter of supersonic particles in one-dimensional quantum liquids
The non-equilibrium dynamics of strongly correlated many-body systems
exhibits some of the most puzzling phenomena and challenging problems in
condensed matter physics. Here we report on essentially exact results on the
time evolution of an impurity injected at a finite velocity into a
one-dimensional quantum liquid. We provide the first quantitative study of the
formation of the correlation hole around a particle in a strongly coupled
many-body quantum system, and find that the resulting correlated state does not
come to a complete stop but reaches a steady state which propagates at a finite
velocity. We also uncover a novel physical phenomenon when the impurity is
injected at supersonic velocities: the correlation hole undergoes long-lived
coherent oscillations around the impurity, an effect we call quantum flutter.
We provide a detailed understanding and an intuitive physical picture of these
intriguing discoveries, and propose an experimental setup where this physics
can be realized and probed directly.Comment: 13 pages, 9 figure
Investigation of reactions between trace gases and functional CuO nanospheres and octahedrons using NEXAFS TXM imaging
In order to take full advantage of novel functional materials in the next generation of sensorial devices scalable processes for their fabrication and utilization are of great importance. Also understanding the processes lending the properties to those materials is essential. Among the most sought after sensor applications are low cost, highly sensitive and selective metal oxide based gas sensors. Yet, the surface reactions responsible for provoking a change in the electrical behavior of gas sensitive layers are insufficiently comprehended. Here, we have used near edge x ray absorption fine structure spectroscopy in combination with x ray microscopy NEXAFS TXM for ex situ measurements, in order to reveal the hydrogen sulfide induced processes at the surface of copper oxide nanoparticles, which are ultimately responsible for triggering a percolation phase transition. For the first time these measurements allow the imaging of trace gas induced reactions and the effect they have on the chemical composition of the metal oxide surface and bulk. This makes the new technique suitable for elucidating adsorption processes in situ and under real operating condition
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