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• 1
Article
Language: English
In: Vakuum in Forschung und Praxis, April 2014, Vol.26(2), pp.42-47
Description: Polymers made of renewable resources increasingly replace conventional plastic materials made of petroleum. Socalled bioplastics can be found e. g. in food industry, for agricultural usage or in the medical field. The range of applications can be further expanded with specialized coating of their surface. Especially in case of food packaging and the usage within medical devices as well as the storage of these composite materials, sterilization or at least the partial reduction of microbial growth is an important issue which needs to be addressed early in the production process. In this work, a commercially available polyhydroxyalkanoate (PHA) pure bioplastic foil of 50 μm thickness was coated with 100 nm of diamond‐like carbon (DLC) and afterwards treated by four different standard methods of sterilization and / or disinfection, namely deep‐freezing, ultraviolet irradiation, autoclaving and immersion in ethanol. The surface morphology of treated DLC‐coated and uncoated samples was investigated and compared to the untreated DLC‐coated and uncoated samples using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Measurements exhibited damage of the composite for autoclaved and in ethanol immersed samples, whereas deep‐frozen and ultraviolet irradiated samples showed no structural changes. These findings clearly demonstrate deep‐freezing and ultraviolet irradiation to be appropriate methods for the disinfection and sterilization, respectively, of the DLC‐coated pure bioplastic foil. DLC‐beschichtete Biokunststoff‐Folie — Auswirkungen verschiedener Sterilisationsmethoden auf die Oberflächenmorphologie Aus erneuerbaren Ressourcen hergestellte Polymere ersetzen zunehmend Erdöl‐basierte konventionelle Kunststoffe. Die sogenannten Biokunststoffe sind z. B. in der Nahrungsmittelindustrie, der Landwirtschaft oder der Medizin zu finden. Ihr Anwendungsspektrum kann durch spezielle Oberflächenbeschichtungen aber noch erweitert werden. Insbesondere in der Nahrungsmittelverpackungsindustrie, bei der Verwendung in medizinischen Apparaturen und Implantaten sowie deren Lagerung ist die Sterilisierung oder zumindest die teilweise Reduzierung der mikrobiellen Aktivität ein wichtiger Aspekt, der bereits frühzeitig im Produktionsprozess berücksichtigt werden muss. In der vorliegenden Arbeit wurde kommerziell erhältliche 50 μm dicke Polyhydroxyalkanoat (PHA)‐Biokunststoff‐Folie mit 100 nm diamant‐ähnlichem Kohlenstoff (DLC) beschichtet und danach mit vier verschiedenen Standardmethoden der Sterilisation und/oder Desinfektion, nämlich UV‐Bestrahlung, Autoklavieren, Tiefkühlung, und Eintauchen in Ethanol, behandelt. Die Oberflächenstruktur der so behandelten Proben (DLC‐beschichtet und unbeschichtet) wurde mittels REM (Rasterelektronenmikroskopie) und AFM (Rasterkraftmikroskopie) untersucht und mit den entsprechenden unbehandelten Proben verglichen. Die Messungen ergaben Beschädigungen des Materialverbundes bei der Behandlung durch Autoklavieren und Ethanol, wohingegen die tiefgekühlten und UV‐bestrahlten Proben keinerlei strukturelle Veränderungen zeigten. Diese Ergebnisse zeigen klar, dass Tiefkühlung und UV‐Bestrahlung geeignete Methoden für die Desinfizierung bzw. Sterilisation dieser DLC‐beschichteten Biokunststoff‐Folien darstellen.
Keywords: Nahrungsmittelindustrie ; Oberflächenbeschichtung ; Sterilisierung ; Produktionsprozess ; Desinfektion ; Tiefkühlen ; Biokunststoff ; Oberflächenmorphologie ; Polymer ; Kunststoff ; Landwirtschaft ; Polyhydroxyalkanoat ; Diamantähnlicher Kohlenstoff ; Ethanol ; Autoklavierung ; Desinfizieren ; Mikrobenwachstum ; Autoklav ; Immersion ; Strukturumwandlung ; Medizinische Anwendung ; Engineering ; Physics;
ISSN: 0947-076X
E-ISSN: 1522-2454
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• 2
Article
Language: English
In: Physical Review B, 13 November 2017, Vol.96(18)
Description: We investigate the demagnetization dynamics of the cycloidal and sinusoidal phases of multiferroic TbMnO$_3$ by means of time-resolved resonant soft x-ray diffraction following excitation by an optical pump. Using orthogonal linear x-ray polarizations, we suceeded in disentangling the response of the multiferroic cycloidal spin order from the sinusoidal antiferromagnetic order in the time domain. This enables us to identify the transient magnetic phase created by intense photoexcitation of the electrons and subsequent heating of the spin system on a picosecond timescale. The transient phase is shown to be a spin density wave, as in the adiabatic case, which nevertheless retains the wave vector of the cycloidal long range order. Two different pump photon energies, 1.55 eV and 3.1 eV, lead to population of the conduction band predominantly via intersite $d$-$d$ transitions or intrasite $p$-$d$ transitions, respectively. We find that the nature of the optical excitation does not play an important role in determining the dynamics of magnetic order melting. Further, we observe that the orbital reconstruction, which is induced by the spin ordering, disappears on a timescale comparable to that of the cycloidal order, attesting to a direct coupling between magnetic and orbital orders. Our observations are discussed in the context of recent theoretical models of demagnetization dynamics in strongly correlated systems, revealing the potential of this type of measurement as a benchmark for such complex theoretical studies.
Keywords: Physics
ISSN: 2469-9950
E-ISSN: 2469-9969
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• 3
Article
Language: English
In: Chemical Physics, 1988, Vol.122(3), pp.387-393
Description: The potential energy surface of the ã 3 A″ 2 state of ammonia has been calculated from highly correlated CEPA electronic wave-functions. The excitation energy T e is calculated to be 43121 cm −1 , and the singlet-triplet separation of the A″ 2 states to be 3370 cm −1 . The equilibrium distance of the planar ã 3 A″ 2 state has been calculated to be 1.067 Å. The dissociation into the NH 2 (X 2 B 1 ) + H( 2 S) products proceeds via a barrier at the following planar geometry: α HNH = 111°, r NH = 1.044 Å in the NH 2 fragment, and R NH = 1.316 Å in the dissociation coordinate. The barrier height is calculated to be 965 cm −1 with an expected accuracy of about 100 cm −1 . The shape of the triple surface along the NH 2 +H pathway has been investigated. It is shown that along this pathway the triplet surface lies below the singlet surface and will, therefore, not influence the dissociation of the Ã 1 A″ 2 state.
Keywords: Chemistry ; Physics
ISSN: 0301-0104
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• 4
Article
Language: English
In: The European Physical Journal C, 2013, Vol.73(3), pp.1-34
Description: The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of $\sqrt{s} = 900~\mbox{GeV}$ and 7 TeV collected during 2009 and 2010. Then, using the decay of K s and Λ particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2–5 % for central isolated hadrons and 1–3 % for the final calorimeter jet energy scale.
Keywords: High Energy Physics - Experiment;
ISSN: 1434-6044
E-ISSN: 1434-6052
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• 5
Article
Language: English
In: The European Physical Journal C, 2012, Vol.72(9), pp.1-21
Description: The results of a search for the production of second generation scalar leptoquarks are presented for final states consisting of either two muons and at least two jets or a muon plus missing transverse momentum and at least two jets. A total of 1.03 fb −1 integrated luminosity of proton-proton collision data produced by the Large Hadron Collider at $\sqrt{s}=7~\mbox{TeV}$ and recorded by the ATLAS detector is used for the search. The event yields in the signal regions are found to be consistent with the Standard Model background expectations. The production of second generation leptoquarks is excluded for a leptoquark mass m LQ 〈594 (685) GeV at 95 % confidence level, for a branching ratio of 0.5 (1.0) for leptoquark decay to a muon and a quark.
Keywords: High Energy Physics - Experiment;
ISSN: 1434-6044
E-ISSN: 1434-6052
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• 6
Article
Language: English
In: The European Physical Journal C, 2012, Vol.72(7), pp.1-22
Description: This letter reports on a search for hypothetical heavy neutrinos, N , and right-handed gauge bosons, W R , in events with high transverse momentum objects which include two reconstructed leptons and at least one hadronic jet. The results were obtained from data corresponding to an integrated luminosity of 2.1 fb −1 collected in proton–proton collisions at $\sqrt{s}=7~\mathrm{TeV}$ with the ATLAS detector at the CERN Large Hadron Collider. No excess above the Standard Model background expectation is observed. Excluded mass regions for Majorana and Dirac neutrinos are presented using two approaches for interactions that violate lepton and lepton-flavor numbers. One approach uses an effective operator framework, the other approach is guided by the Left–Right Symmetric Model. The results described in this letter represent the most stringent limits to date on the masses of heavy neutrinos and W R bosons obtained in direct searches.
Keywords: Letter;
ISSN: 1434-6044
E-ISSN: 1434-6052
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• 7
Article
Language: English
In: Journal of High Energy Physics, 2011, Vol.2011(9), pp.1-36
Description: A measurement of jet activity in the rapidity interval bounded by a dijet system is presented. Events are vetoed if a jet with transverse momentum greater than 20 GeV is found between the two boundary jets. The fraction of dijet events that survive the jet veto is presented for boundary jets that are separated by up to six units of rapidity and with mean transverse momentum 50 〈  ${\bar{p}_{\text{T}}}$  〈 500 GeV. The mean multiplicity of jets above the veto scale in the rapidity interval bounded by the dijet system is also presented as an alternative method for quantifying perturbative QCD emission. The data are compared to a next-to-leading order plus parton shower prediction from the powheg-box , an all-order resummation using the hej calculation and the pythia , herwig ++ and alpgen event generators. The measurement was performed using pp collisions at $\sqrt {s} = 7$ TeV using data recorded by the ATLAS detector in 2010.
E-ISSN: 1029-8479
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• 8
Article
Language: English
In: The European Physical Journal C, 2012, Vol.72(4), pp.1-20
Description: In models of anomaly-mediated supersymmetry breaking (AMSB), the lightest chargino is predicted to have a lifetime long enough to be detected in collider experiments. This letter explores AMSB scenarios in pp collisions at $\sqrt {s}=7\ \mathrm{TeV}$ by attempting to identify decaying charginos which result in tracks that appear to have few associated hits in the outer region of the tracking system. The search was based on data corresponding to an integrated luminosity of 1.02 fb −1 collected with the ATLAS detector in 2011. The p T spectrum of candidate tracks is found to be consistent with the expectation from Standard Model background processes and constraints on the lifetime and the production cross section were obtained. In the minimal AMSB framework with m 3/2 〈32 TeV, m 0 〈1.5 TeV, tan β =5 and μ 〉0, a chargino having mass below 92 GeV and a lifetime between 0.5 ns and 2 ns is excluded at 95 % confidence level.
Keywords: High Energy Physics - Experiment;
ISSN: 1434-6044
E-ISSN: 1434-6052
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• 9
Article
Language: English
In: The European Physical Journal C, 2012, Vol.72(6), pp.1-30
Description: The top quark mass has been measured using the template method in the $t\bar{t}\to\mathrm{lepton}+\mathrm{jets}$ channel based on data recorded in 2011 with the ATLAS detector at the LHC. The data were taken at a proton-proton centre-of-mass energy of $\sqrt{s}=7\ \mbox{TeV}$ and correspond to an integrated luminosity of 1.04 fb −1 . The analyses in the e +jets and μ +jets decay channels yield consistent results. The top quark mass is measured to be m top =174.5±0.6 stat ±2.3 syst GeV.
Keywords: Regular Article - Experimental Physics;
ISSN: 1434-6044
E-ISSN: 1434-6052
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• 10
Article
Language: English
In: The European Physical Journal C, 2011, Vol.71(12), pp.1-17
Description: A search is presented for a high mass neutral particle that decays directly to the e ± μ ∓ final state. The data sample was recorded by the ATLAS detector in $\sqrt{s}=7\mbox{~TeV}$ pp collisions at the LHC from March to June 2011 and corresponds to an integrated luminosity of 1.07 fb −1 . The data are found to be consistent with the Standard Model background. The high e ± μ ∓ mass region is used to set 95% confidence level upper limits on the production of two possible new physics processes: tau sneutrinos in an R -parity violating supersymmetric model and Z ′-like vector bosons in a lepton flavor violating model.
Keywords: High Energy Physics - Experiment;
ISSN: 1434-6044
E-ISSN: 1434-6052
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