Neues hochauflösendes, miniaturisiertes und monolithisches Tiltmeter der TU Ilmenau

Der Beitrag beschreibt die Entwicklung eines Tiltmeters zur hochpräzisen Neigungsmessung. Die Auflösung liegt bei < 1 nrad wobei der Messbereich ±2 mrad beträgt

Konstruktive Gestaltung des optimierten Positionier- und Kraftmesssystems der TU Ilmenau zur Kalibrierung von Federkonstanten von Mikrokraftsensoren

Der Beitrag beschreibt die aus den Anforderungen abgeleitete konstruktive Gestaltung des optimierten Positionier- und Kraftmesssystems der TU Ilmenau

Unsicherheitsbeiträge der Krafteinleitung bei der Kalibrierung der Federkonstanten von AFM Cantilevern

Bei der Kalibrierung der Federsteifigkeit von AFM Cantilevern liefert deren Fehlausrichtung bezüglich des Kalibriersystems einen signifikanten Beitrag zur Messunsicherheit. In dieser Veröffentlichung werden diese Messunsicherheitsbeiträge auf Basis von analytischen und numerischen Modellen beschrieben sowie mit geeigneten Messungen überprüft. Das Ziel ist die Reduzierung der Messunsicherheit der Federsteifigkeit

Calibration of the torsion force measurement system for the Lorentz force velocimetry application

The in this paper described torsion force measurement system contributes to the Lorentz force velocimetry application, where the horizontal force in combination with dead load of 1 kg is measured. The theoretically calculated stiffness of the system is 0.5 N/m, undamped nature frequency is 0.06 Hz and it is expected to achieve the force resolution of 0.5 nN. Initially the electrical voltage as the output signal of the photoelectrical position sensor is converted into angle with an autocollimator system. Then the output signal of the position sensor is calibrated into force with the help of a known tilt force generated by tilt angle and a normal mass piece, the convert factors for the two positon sensors are 37.1038 µN/V and 38.7247 µN/V. A standard deviation of 5.5 nN over one hour has also been achieved and the linear working range of the system is nearly ± 40 µN

Modelling phagosomal lipid networks that regulate actin assembly

<p>Abstract</p> <p>Background</p> <p>When purified phagosomes are incubated in the presence of actin under appropriate conditions, microfilaments start growing from the membrane in a process that is affected by ATP and the lipid composition of the membrane. Isolated phagosomes are metabolically active organelles that contain enzymes and metabolites necessary for lipid interconversion. Hence, addition of ATP, lipids, and actin to the system alter the steady-state composition of the phagosomal membrane at the same time that the actin nucleation is initiated. Our aim was to model all these processes in parallel.</p> <p>Results</p> <p>We compiled detailed experimental data on the effects of different lipids and ATP on actin nucleation and we investigated experimentally lipid interconversion and ATP metabolism in phagosomes by using suitable radioactive compounds.</p> <p>In a first step, a complex lipid network interconnected by chemical reactions catalyzed by known enzymes was modelled in COPASI (Complex Pathway Simulator). However, several lines of experimental evidence indicated that only the phosphatidylinositol branch of the network was active, an observation that dramatically reduced the number of parameters in the model. The results also indicated that a lipid network-independent ATP-consuming activity should be included in the model. When this activity was introduced, the set of differential equations satisfactorily reproduced the experimental data. On the other hand, a molecular mechanism connecting membrane lipids, ATP, and the actin nucleation process is still missing. We therefore adopted a phenomenological (black-box) approach to represent the empirical observations. We proposed that lipids and ATP influence the dynamic interconversion between active and inactive actin nucleation sites. With this simple model, all the experimental data were satisfactorily fitted with a single positive parameter per lipid and ATP.</p> <p>Conclusion</p> <p>By establishing an active 'dialogue' between an initial complex model and experimental observations, we could narrow the set of differential equations and parameters required to characterize the time-dependent changes of metabolites influencing actin nucleation on phagosomes. For this, the global model was dissected into three sub-models: ATP consumption, lipid interconversion, and nucleation of actin on phagosomal membranes. This scheme allowed us to describe this complex system with a relatively small set of differential equations and kinetic parameters that satisfactorily reproduced the experimental data.</p

Progress of nanopositioning and nanomeasuring machines for cross-scale measurement with sub-nanometre precision

Nanopositioning and nanomeasuring machines (NPM-machines), developed at Technische Universität Ilmenau, have provided high-precision measurement and positioning of objects across ten decades, from 20 pm resolution up to 200 mm measuring range. They work on the basis of the error-minimal, extended six degrees of freedom Abbe-comparator principle, with high-precision fibre-coupled laser interferometers and optical or atomic force probes. These machines are suitable not only for measuring but also for positioning with an outstanding sub-nanometre performance. Measurements on precision step heights up to 5 mm show a repeatability of 20 pm. Consecutive step positioning of 80 pm can be demonstrated. With the new approach of an atomic clock-stabilized He–Ne-laser via a high-stable-frequency comb, we achieve a frequency stability of less than 300 Hz, respectively 0.6 ċ 10−12 relative frequency stability within 1 h at an integration time of 1 s. For the first time, we can demonstrate a direct, permanent and unbroken chain of traceability between the laser interferometric measurement within an NPM-machine and a GPS satellite-based atomic clock. This paper presents a closer insight into the scientific and metrological background as well as unrivalled measurement results, and discusses the great possibilities of this new technology