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Hamburg, Germany

Bente K.,University of Lubeck | Weber M.,University of Lubeck | Graeser M.,University of Lubeck | Sattel T.F.,Philips | And 2 more authors.
IEEE Transactions on Medical Imaging | Year: 2015

It has been shown that magnetic particle imaging (MPI), an imaging method suggested in 2005, is capable of measuring the spatial distribution of magnetic nanoparticles. Since the particles can be administered as biocompatible suspensions, this method promises to perform well as a tracer-based medical imaging technique. It is capable of generating real-time images, which will be useful in interventional procedures, without utilizing any harmful radiation. To obtain a signal from the administered superparamagnetic iron oxide (SPIO) particles, a sinusoidal changing external homogeneous magnetic field is applied. To achieve spatial encoding, a gradient field is superimposed. Conventional MPI works with a spatial encoding field that features a field free point (FFP). To increase sensitivity, an improved spatial encoding field, featuring a field free line (FFL) can be used. Previous FFL scanners, featuring a 1-D excitation, could demonstrate the feasibility of the FFL-based MPI imaging process. In this work, an FFL-based MPI scanner is presented that features a 2-D excitation field and, for the first time, an electronic rotation of the spatial encoding field. Furthermore, the role of relaxation effects in MPI is starting to move to the center of interest. Nevertheless, no reconstruction schemes presented thus far include a dynamical particle model for image reconstruction. A first application of a model that accounts for relaxation effects in the reconstruction of MPI images is presented here in the form of a simplified, but well performing strategy for signal deconvolution. The results demonstrate the high impact of relaxation deconvolution on the MPI imaging process. © 2014 IEEE. Source

Jin M.,KRUSS GmbH | Sanedrin R.,KRUSS United States | Frese D.,KRUSS GmbH | Scheithauer C.,KRUSS GmbH | Willers T.,KRUSS GmbH
Colloid and Polymer Science | Year: 2016

In general, the optical determination of static and advancing contact angle is made on drops applied or extended, respectively, onto a substrate through the use of thin solid needles. Although this method is used extensively, this way of dosing can be time consuming, cumbersome and if not performed meticulously can lead to erroneous results. Herein, we present an alternative way of applying drops onto substrates using a liquid jet produced by a liquid pressure dosing system acting as a “liquid needle”. We performed a comparative static contact angle study on 14 different surfaces with two different liquids (water and diiodomethane) utilizing two different ways of dosing: the conventional solid and a novel liquid needle-based technique. We found, for all but one sample, that the obtained results on μl size drops were comparable within the experimental error bars provided the liquid needle is thin enough. Observed differences are explained by the special characteristics of either way of dosing. In addition, we demonstrate how the liquid pressure-based dosing system facilitates high-speed optical advancing contact angle measurement by expanding a drop from 0.1 to 22 μl within less than 1.2 s but yet providing constant contact angle versus drop base diameter curves. The obtained results were compared with data from tensiometric dynamic Wilhelmy contact angle measurements. These data, in conjunction with sequences of live images of the dosing process of the liquid pressure dosing system, illustrate how this system can replace the solid needle by a liquid needle. © 2015 Springer-Verlag Berlin Heidelberg Source

Oetjen K.,KRUSS GmbH | Bilke-Krause C.,KRUSS GmbH | Madani M.,University of Hamburg | Willers T.,KRUSS GmbH
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2014

We investigated the foaming properties of four different types of milk: ultra-high-temperature treated milk and pasteurized milk, each with 1.5 and 3.5% fat content. Foamability and foam stability were investigated at various temperatures between 5 and 60. °C. For both the foamability and the foam stability, we observed a pronounced minimum at 25. °C. At 40. °C the foam stability varied considerably depending on the type of milk. These differences can be related to different initial bubble-size distributions. The time dependence of the bubble size distribution was measured at room temperature and at 40. °C. © 2014 Elsevier B.V. Source

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