31 research outputs found
Direct <i>Q</i> -Value Determination of the <i>ÎČ<sup>-</sup></i> Decay of <sup>187</sup>Re
The cyclotron frequency ratio of 187Os29+ to 187Re29+ ions was measured with the Penning-trap mass spectrometer PENTATRAP. The achieved result of R=1.000â000â013â882(5) is to date the most precise such measurement performed on ions. Furthermore, the total binding-energy difference of the 29 missing electrons in Re and Os was calculated by relativistic multiconfiguration methods, yielding the value of ÎE=53.5(10)ââeV. Finally, using the achieved results, the mass difference between neutral 187Re and 187Os, i.e., the Q value of the ÎČ-â decay of 187Re, is determined to be 2470.9(13) eV
Electrostatic immobilization of antimicrobial peptides on polyethylenimine and their antibacterial effect against Staphylococcus epidermidis
Staphylococcus epidermidis is a gram-positive bacterium, and one of the most prevalent causes of nosocomial infections due to its strong ability to form biofilms on catheters and surgical implants. Here we explore the antimicrobial properties of Tet-124 peptides, which are part of the innate defense against different multicellular organisms in nature. Two different Tet-124 peptides were immobilized on a polyethylenimine (PEI) film to determine their impact on the antimicrobial properties: KLWWMIRRW (Tet-124), which contains only natural amino acids, and KLWWMIRRWG-(F-Br)-G (F-Br- 4-Bromophenylalanine), a modified Tet-124 sequence with the addition of an unnatural amino acid. The immobilization was obtained as a result of the electrostatic interaction between PEI amino groups and the C-terminal carboxylic groups of tryptophan and glycine amino acids of Tet-124 and Tet-124-Br peptides, respectively. The process was monitored and studied by water contact angle, Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and Quartz Crystal Microbalance with Dissipation (QCM-D) measurements. The antibacterial effect of our samples against S. epidermis was evaluated by the spread plate counting method, and cytotoxicity was tested using fibroblast cultures. Our results indicate the feasibility to immobilize electrostatically both Tet-124 peptides for biomedical application
High-resolution and low-background Ho spectrum: interpretation of the resonance tails
The determination of the effective electron neutrino mass via kinematic analysis of beta and electron capture spectra is considered to be model-independent since it relies on energy and momentum conservation. At the same time the precise description of the expected spectrum goes beyond the simple phase space term. In particular for electron capture processes, many-body electron-electron interactions lead to additional structures besides the main resonances in calorimetrically measured spectra. A precise description of the Ho spectrum is fundamental for understanding the impact of low intensity structures at the endpoint region where a finite neutrino mass affects the shape most strongly. We present a low-background and high-energy resolution measurement of the Ho spectrum obtained in the framework of the ECHo experiment. We study the line shape of the main resonances and multiplets with intensities spanning three orders of magnitude. We discuss the need to introduce an asymmetric line shape contribution due to AugerâMeitner decay of states above the auto-ionisation threshold. With this we determine an enhancement of count rate at the endpoint region of about a factor of 2, which in turn leads to an equal reduction in the required exposure of the experiment to achieve a given sensitivity on the effective electron neutrino mass
The electron capture in Ho experiment â ECHo
Neutrinos, and in particular their tiny but non-vanishing masses, can be considered one of the doors towards physics beyond the Standard Model. Precision measurements of the kinematics of weak interactions, in particular of the H ÎČ-decay and the Ho electron capture (EC), represent the only model independent approach to determine the absolute scale of neutrino masses. The electron capture in Ho experiment, ECHo, is designed to reach sub-eV sensitivity on the electron neutrino mass by means of the analysis of the calorimetrically measured electron capture spectrum of the nuclide Ho. The maximum energy available for this decay, about 2.8âkeV, constrains the type of detectors that can be used. Arrays of low temperature metallic magnetic calorimeters (MMCs) are being developed to measure the Ho EC spectrum with energy resolution below 3âeV FWHM and with a time resolution below 1âÎŒs. To achieve the sub-eV sensitivity on the electron neutrino mass, together with the detector optimization, the availability of large ultra-pure Ho samples, the identification and suppression of background sources as well as the precise parametrization of the Ho EC spectrum are of utmost importance. The high-energy resolution Ho spectra measured with the first MMC prototypes with ion-implanted Ho set the basis for the ECHo experiment. We describe the conceptual design of ECHo and motivate the strategies we have adopted to carry on the present medium scale experiment, ECHo-1K. In this experiment, the use of 1âkBq Ho will allow to reach a neutrino mass sensitivity below 10âeV/c. We then discuss how the results being achieved in ECHo-1k will guide the design of the next stage of the ECHo experiment, ECHo-1M, where a source of the order of 1âMBq Ho embedded in large MMCs arrays will allow to reach sub-eV sensitivity on the electron neutrino mass
Medizinische Muschelproteine - Der Natur nachempfundene Klebstoffe helfen heilen
Die gemeine Miesmuschel (Mytilus edulis) bildet dauerhafte, feste Klebverbindungen in Wasser. Die Muschel haftet mit ByssusfĂ€den ĂŒber eine Plaque (Klebstoffpunkt) am Substrat. Die Plaque besteht hauptsĂ€chlich aus als Mytilus edulis foot protein (Mefp) bezeichneten Proteinen und ist das biologische Analogon zu einem technischen Klebstoff. Eine zentrale Rolle spielt Mefp-1, das aus Folgen von zehn AminosĂ€uren besteht. Diese Dekapeptideinheit wiederholt sich etwa 75- bis 80-mal und enthĂ€lt nach der Biosynthese enzymatisch modifizierte AminosĂ€uren wie Hydroxyprolin (Hyp) und Dihydroxylphenylalanin (Dopa). In der Natur initiiert eine Catechol-Oxidase die Quervernetzung enzymatisch (HĂ€rtungszeit etwa drei Minuten). In vitro startet die HĂ€rtung durch oxidierende Agenzien wie NaJO4 oder H2O2. In den vergangenen Jahren wurden verschiedene AnsĂ€tze verfolgt, die Potenziale des Muschelklebstoffs und seiner Einzelkomponenten fĂŒr den Menschen nutzbar zu machen. Hybridsysteme, basierend auf synthetischen Polymeren und der Dopa-AminosĂ€ure, wurden fĂŒr die Herstellung von Hydrogelen fĂŒr medizinische Applikationen synthetisiert. Zuasmmenfassung: Die Miesmuschel bildet dauerhafte, feste Klebverbindungen in Salzwasser. Dabei sorgen Proteine fĂŒr gute Haftung an verschiedenen UntergrĂŒnden. In der Natur wird das Kleben enzymatisch initiiert, in vitro startet die HĂ€rtung durch oxidjerende Agenzien wie NaJO4 oder H2O2. Miesmuschelproteine können ein Ansatz bei der Entwicklung medizinischer Klebstoffe sein
An innovative, preventive acting âbioinspiredâ antimicrobial surface based on peptides for space and Earth
Antimicrobial surfaces are a well suited technology to prevent and reduce microbial loads in sensitive areas, where high humidity and temperature levels are causing increased microbial loads. These can endanger human health, health of organisms e.g. in bioregenerative life-support systems as well as technical equipment. Antimicrobial surfaces are preventively beneficial
âą in spaceflight â e.g. in confined environments in LEO and during exploration activities, to support breeding activities of e.g. algae in bioreactors and for biological experiments, and furthermore to meet the COSPAR planetary protection policy
âą as well as also on Earth - in hygiene areas during medical activities and food handling, in swimming baths, bathrooms, public transportation, submarines, greenhouses etc.
For its dedicated use in space as well as on Earth, antimicrobial surfaces must be free of any toxic substance, otherwise higher non-target organisms would be affected. That means, that synthetic chemicals, silver, copper etc., as used until now, are not a suited solution - which in addition might lead to resistances of the bacteria to these toxic substances and are acting rather unspecific.
A suited alternative to overcome these problems are bioinspired technologies as using antimicrobial peptides from nature (e.g. from frog skin etc.), immobilized on surfaces. High flexibility concerning the microbial target, acting specifically, low toxicity and an absence of resistances are the main advantages.
As a logical step, the goal of the ESA-funded project BALS (Bioinspired antimicrobial lacquer for space) was the development of a new innovative antimicrobial acting lacquer based on peptides. Project partners were OHB System, Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) (both Bremen, Germany) as well as the German Aerospace Center, Institute of Aerospace Medicine (Cologne, Germany).
The developed antimicrobial lacquer with immobilized peptides showed an antimicrobial activity against S. cohnii and E. coli, compared to a reference lacquer without peptides. Its adhesion strength on space relevant substrates was demonstrated in a ECSS-Q-70-13A-test series, measuring the peel and pull-off strength using pressure-sensitive tapes. In addition, the absence of effects on higher organisms and the environment was shown in a laboratory aquatic biological multispecies test system (AquaHabÂź).
With the successful demonstration of feasibility and use (TRL 4) of such a bioinspired antimicrobial lacquer and including these promising test results, all preconditions are now given for the further development and qualification until a full commercial exploitation, ready to be used in application fields in space and on Earth
A NEW PREVENTIVE ACTING BIOINSPIRED ANTIMICROBIAL SURFACE - ACTUAL STATUS AND FIRST RESULTS
Antimicrobial surfaces are a highly promising approach in preventing/ reducing microbial loads in
sensitive areas. There, high humidity and temperature levels are causing microbial contamination -
endangering human health, health of organisms e.g. in bioregenerative life-support systems as well as
technical equipment. Antimicrobial surfaces are beneficial âą in spaceflight - w.r.t. activities in confined
environments in LEO and during exploration activities - to support breeding activities of e.g. algae in
bioreactors, biological experiments and to meet the COSPAR planetary protection policy âą as well as on
Earth - in hygiene areas during medical activities and food handling, in swimming baths, bathrooms etc..
For confined environments in space as well as on Earth, antimicrobial surfaces must be free of any
toxic substance, otherwise higher non-target organisms would be affected. Thus, synthetic chemicals,
silver, copper etc., as used until now, are not a suited solution, which in addition might lead to resistances
of the bacteria to these toxic substances and are acting rather unspecific. Bioinspired technologies as
using antimicrobial peptides from nature (e.g. from frog skin etc.), immobilised on surfaces, are a suited
alternative. High flexibility concerning the microbial target, low toxicity and an absence of resistances
are the main advantages.
As a consequence, the goal of the ESA-funded project BALS (Bio-inspired antimicrobial lacquer for
space) was the development of a new innovative antimicrobial acting lacquer based on peptides. Project
partners were OHB System, Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) (both Bremen, Germany) as well as the German Aerospace Center, Institute of Aerospace
Medicine (Cologne, Germany).
An overview about goals, technology and test results (w.r.t. antimicrobial activity, adhesion on substrates as well as absence of effects on higher organisms) of the BALS activity will be given at the
symposium. Furthermore, an outlook about the next development and qualification steps until routine
application in space and on Earth will be part of the presentation
Mutual interaction of adhesion and molecular conformation in interphases: The next step in adhesion science
A New Experiment for the Measurement of the g-Factors of <sup>3</sup>He<sup>+</sup> and <sup>3</sup>He<sup>2+</sup>.
We describe a new experiment that aims at a parts per billion measurement of the nuclear magnetic moment of 3He2+ and a 100 parts per trillion measurement of the Zeeman effect of the ground-state hyperfine splitting of 3He+. To enable ultrafast and efficient experiment cycles the experiment relies on new technologies such as sympathetic laser cooling of single 3He-ions coupled to a cloud of Doppler-cooled 9Be-ions in a Penning trap or a novel spin-state detection scheme