Microplasmas and applications Becker, K H; Schoenbach, K H; Eden, J G
Journal of physics. D, Applied physics,
02/2006, Letnik:
39, Številka:
3
Journal Article
Recenzirano
Atmospheric-pressure, non-equilibrium plasmas are susceptible to instabilities and, in particular, to arcing (glow-to-arc transition). Spatially confining the plasma to dimensions of 1 mm or less is ...a promising approach to the generation and maintenance of stable, glow discharges at atmospheric-pressure. Often referred to as microdischarges or microplasmas, these weakly-ionized discharges represent a new and fascinating realm of plasma science, where issues such as the possible breakdown of 'pd scaling' and the role of boundary-dominated phenomena come to the fore. Microplasmas are generated under conditions that promote the efficient production of transient molecular species such as the rare gas excimers, which generally are formed by three-body collisions. Pulsed excitation on a sub-microsecond time scale results in microplasmas with significant shifts in both the temperatures and energy distribution functions associated with the ions and electrons. This allows for the selective production of chemically reactive species and opens the door to a wide range of new applications of microplasmas. The implementation of semiconductor and microelectronics and MEMs microfabrication techniques has resulted in the realization of microplasma arrays as large as 250,000 devices. Fabricated in silicon or ceramics with characteristic device dimensions as small as 10 mum and at packing densities up to 104 cm-2, these arrays offer optical and electrical characteristics well suited for applications in medical diagnostics, displays and environmental sensing. Several microplasma device structures, including their fundamental properties and selected applications, will be discussed.
ABSTRACT Evidence for an extraterrestrial flux of high-energy neutrinos has now been found in multiple searches with the IceCube detector. The first solid evidence was provided by a search for ...neutrino events with deposited energies TeV and interaction vertices inside the instrumented volume. Recent analyses suggest that the extraterrestrial flux extends to lower energies and is also visible with throughgoing, -induced tracks from the Northern Hemisphere. Here, we combine the results from six different IceCube searches for astrophysical neutrinos in a maximum-likelihood analysis. The combined event sample features high-statistics samples of shower-like and track-like events. The data are fit in up to three observables: energy, zenith angle, and event topology. Assuming the astrophysical neutrino flux to be isotropic and to consist of equal flavors at Earth, the all-flavor spectrum with neutrino energies between 25 TeV and 2.8 PeV is well described by an unbroken power law with best-fit spectral index −2.50 0.09 and a flux at 100 TeV of . Under the same assumptions, an unbroken power law with index −2 is disfavored with a significance of 3.8 (p = 0.0066%) with respect to the best fit. This significance is reduced to 2.1 (p = 1.7%) if instead we compare the best fit to a spectrum with index −2 that has an exponential cut-off at high energies. Allowing the electron-neutrino flux to deviate from the other two flavors, we find a e fraction of 0.18 0.11 at Earth. The sole production of electron neutrinos, which would be characteristic of neutron-decay-dominated sources, is rejected with a significance of 3.6 (p = 0.014%).
We present results on searches for point-like sources of neutrinos using four years of IceCube data, including the first year of data from the completed 86 string detector. The total livetime of the ...combined data set is 1373 days. For an E super(-2) spectrum, the observed 90% C.L. flux upper limits are ~10 super(-12) TeV super(-1) cm super(-2) s super(-1) for energies between 1 TeV and 1 PeV in the northern sky and ~10 super(-11) TeV super(-1) cm super(-2) s super(-1) for energies between 100 TeV and 100 PeV in the southern sky. This represents a 40% improvement compared to previous publications, resulting from both the additional year of data and the introduction of improved reconstructions. In addition, we present the first results from an all-sky search for extended sources of neutrinos. We update the results of searches for neutrino emission from stacked catalogs of sources and test five new catalogs; two of Galactic supernova remnants and three of active galactic nuclei. In all cases, the data are compatible with the background-only hypothesis, and upper limits on the flux of muon neutrinos are reported for the sources considered.
Host-microbe symbioses rely on the successful transmission or acquisition of symbionts in each new generation. Amphibians host a diverse cutaneous microbiota, and many of these symbionts appear to be ...mutualistic and may limit infection by the chytrid fungus, Batrachochytrium dendrobatidis, which has caused global amphibian population declines and extinctions in recent decades. Using bar-coded 454 pyrosequencing of the 16S rRNA gene, we addressed the question of symbiont transmission by examining variation in amphibian skin microbiota across species and sites and in direct relation to environmental microbes. Although acquisition of environmental microbes occurs in some host-symbiont systems, this has not been extensively examined in free-living vertebrate-microbe symbioses. Juvenile bullfrogs (Rana catesbeiana), adult red-spotted newts (Notophthalmus viridescens), pond water and pond substrate were sampled at a single pond to examine host-specificity and potential environmental transmission of microbiota. To assess population level variation in skin microbiota, adult newts from two additional sites were also sampled. Cohabiting bullfrogs and newts had distinct microbial communities, as did newts across the three sites. The microbial communities of amphibians and the environment were distinct; there was very little overlap in the amphibians' core microbes and the most abundant environmental microbes, and the relative abundances of OTUs that were shared by amphibians and the environment were inversely related. These results suggest that, in a host species-specific manner, amphibian skin may select for microbes that are generally in low abundance in the environment.
Regulated proteolysis is essential for the normal physiology of all organisms. While all eukaryotes and archaea use proteasomes for protein degradation, only certain orders of bacteria have ...proteasomes, whose functions are likely as diverse as the species that use them. In this review, we discuss the most recent developments in the understanding of how proteins are targeted to proteasomes for degradation, including ATP-dependent and -independent mechanisms, and the roles of proteasome-dependent degradation in protein quality control and the regulation of cellular physiology. Furthermore, we explore newly established functions of proteasome system accessory factors that function independently of proteolysis.
•Symbiotic microbes contribute to host health and can be altered by captivity.•We investigated the effects of captivity on Panamanian golden frog skin microbiota.•Microbial diversity differed between ...captive and wild frog microbiota.•However, captive frogs shared 70% of their microbiota with wild frogs.•Captive management policies should consider impacts of captivity on host microbiota.
For many threatened vertebrates, captivity may be the only option for species survival. Maintaining species in captivity prior to reintroduction presents many challenges, including the need to preserve genetic diversity and mitigation of disease risks. Recent studies suggest that captivity can alter the suite of symbiotic microbes that play important roles in host health. The Panamanian golden frog (Atelopus zeteki) has not been seen in its native habitat in Panamá since 2009. Along with habitat loss and illegal collecting, the lethal disease chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is responsible for the severe decline of this species. Prior to the spread of Bd into golden frog habitat, conservation organizations collected golden frogs and placed them in captive survival assurance colonies. The skin of amphibians is host to a diverse resident bacterial community, which acts as a defense mechanism in some amphibians to inhibit pathogens. We characterized the cutaneous bacterial community from wild and F1 captive golden frogs originating from the same population with Illumina sequencing to assess how long-term captivity has affected this community. We found that species richness, phylogenetic diversity, and community structure of the skin microbiota was significantly different between wild and captive golden frogs. However, after approximately eight years of living in captivity, the offspring of the original captive golden frogs still shared 70% of their microbial community with wild frogs. These results demonstrate that host-associated microbial communities can be significantly altered by captive management, but most of the community composition can be preserved.
ABSTRACT We present constraints derived from a search of four years of IceCube data for a prompt neutrino flux from gamma-ray bursts (GRBs). A single low-significance neutrino, compatible with the ...atmospheric neutrino background, was found in coincidence with one of the 506 observed bursts. Although GRBs have been proposed as candidate sources for ultra-high-energy cosmic rays, our limits on the neutrino flux disfavor much of the parameter space for the latest models. We also find that no more than ∼1% of the recently observed astrophysical neutrino flux consists of prompt emission from GRBs that are potentially observable by existing satellites.
Insulin glargine is processed in vivo into soluble 21A‐Gly‐human insulin (M1), the principal moiety responsible for metabolic effects, and subsequently into M2. This sub‐study compared metabolism and ...metabolite pharmacokinetic (PK) profiles of investigational new insulin glargine U300 (Gla‐300) with insulin glargine 100 U/ml (Gla‐100, Lantus®, Sanofi‐Aventis Deutschland GmbH, Frankfurt am Main, Germany) in people with type 1 diabetes. Participants received 0.4 (n = 18) or 0.6 U/kg Gla‐300 (n = 12), and 0.4 U/kg Gla‐100 (n = 30) once daily in randomized order for 8 days prior to a 36‐h euglycaemic clamp. Metabolites were quantified using immunoaffinity enrichment and liquid chromatography tandem mass spectrometry (LC‐MS/MS). Glargine metabolism was the same regardless of Gla‐100 or Gla‐300 administration; M1 was confirmed as the principal active moiety circulating in blood. Steady state concentrations of M1 were achieved after 2 days for Gla‐100, and 4 days for Gla‐300. Steady state M1 values defined prolonged and even flatter PK profiles after Gla‐300 administration compared with M1 profiles after Gla‐100.
ABSTRACT In this paper searches for flaring astrophysical neutrino sources and sources with periodic emission with the IceCube neutrino telescope are presented. In contrast to time-integrated ...searches, where steady emission is assumed, the analyses presented here look for a time-dependent signal of neutrinos using the information from the neutrino arrival times to enhance the discovery potential. A search was performed for correlations between neutrino arrival times and directions, as well as neutrino emission following time-dependent light curves, sporadic emission, or periodicities of candidate sources. These include active galactic nuclei, soft γ-ray repeaters, supernova remnants hosting pulsars, microquasars, and X-ray binaries. The work presented here updates and extends previously published results to a longer period that covers 4 years of data from 2008 April 5 to 2012 May 16, including the first year of operation of the completed 86 string detector. The analyses did not find any significant time-dependent point sources of neutrinos, and the results were used to set upper limits on the neutrino flux from source candidates.
The first full‐color polymer organic light‐emitting diode (OLED) display is reported, fabricated by a direct photolithography process, that is, a process that allows direct structuring of the ...electroluminescent layer of the OLED by exposure to UV light. The required photosensitivity is introduced by attaching oxetane side groups to the backbone of red‐, green‐, and blue‐light‐emitting polymers. This allows for the use of photolithography to selectively crosslink thin films of these polymers. Hence the solution‐based process requires neither an additional etching step, as is the case for conventional photoresist lithography, nor does it rely on the use of prestructured substrates, which are required if ink‐jet printing is used to pixilate the emissive layer. The process allows for low‐cost display fabrication without sacrificing resolution: Structures with features in the range of 2 μm are obtained by patterning the emitting polymers via UV illumination through an ultrafine shadow mask. Compared to state‐of‐the‐art fluorescent OLEDs, the display prototype (pixel size 200 μm × 600 μm) presented here shows very good efficiency as well as good color saturation for all three colors. The application in solid‐state lighting is also possible: Pure white light Commision Internationale de l'Éclairage (CIE) values of 0.33, 0.33 and color rendering index (CRI) of 76 is obtained at an efficiency of 5 cd A–1 by mixing the three colors in the appropriate ratio. For further enhancement of the device efficiency, an additional hole‐transport layer (HTL), which is also photo‐crosslinkable and therefore suitable to fabricate multilayer devices from solution, is embedded between the anode and the electroluminescent layer.
Full‐color polymer OLED displays are fabricated by using a novel photolithographic technique (see figure). Electroluminescent polymers with photoresist‐like properties are made by attaching oxetane side groups to the polymers, allowing the structuring of thin films of these materials at high speed and high resolution.
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