Refine
Year of publication
- 2024 (15)
- 2023 (38)
- 2022 (48)
- 2021 (55)
- 2020 (52)
- 2019 (69)
- 2018 (67)
- 2017 (67)
- 2016 (54)
- 2015 (70)
- 2014 (65)
- 2013 (65)
- 2012 (72)
- 2011 (82)
- 2010 (72)
- 2009 (85)
- 2008 (61)
- 2007 (57)
- 2006 (75)
- 2005 (48)
- 2004 (85)
- 2003 (57)
- 2002 (55)
- 2001 (54)
- 2000 (65)
- 1999 (40)
- 1998 (39)
- 1997 (36)
- 1996 (32)
- 1995 (19)
- 1994 (13)
- 1993 (19)
- 1992 (13)
- 1991 (12)
- 1990 (17)
- 1989 (21)
- 1988 (22)
- 1987 (26)
- 1986 (7)
- 1985 (10)
- 1984 (9)
- 1983 (6)
- 1982 (24)
- 1981 (16)
- 1980 (30)
- 1979 (20)
- 1978 (27)
- 1977 (13)
- 1976 (16)
- 1975 (14)
- 1974 (4)
- 1973 (3)
- 1972 (6)
- 1971 (1)
- 1969 (1)
- 1968 (2)
- 1967 (1)
Document Type
- Article (1578)
- Conference Proceeding (239)
- Book (96)
- Part of a Book (59)
- Doctoral Thesis (27)
- Patent (17)
- Report (15)
- Other (8)
- Habilitation (4)
- Lecture (3)
- Preprint (3)
- Course Material (1)
- Review (1)
- Talk (1)
Keywords
- Biosensor (25)
- Finite-Elemente-Methode (16)
- CAD (15)
- civil engineering (14)
- Bauingenieurwesen (13)
- Einspielen <Werkstoff> (13)
- shakedown analysis (9)
- FEM (6)
- Limit analysis (6)
- Shakedown analysis (6)
- limit analysis (6)
- Clusterion (5)
- Air purification (4)
- Einspielanalyse (4)
- Hämoglobin (4)
- LAPS (4)
- Lipopolysaccharide (4)
- Luftreiniger (4)
- Natural language processing (4)
- Plasmacluster ion technology (4)
Institute
- Fachbereich Medizintechnik und Technomathematik (2052) (remove)
Dual frequency magnetic excitation of magnetic nanoparticles (MNP) enables enhanced biosensing applications. This was studied from an experimental and theoretical perspective: nonlinear sum-frequency components of MNP exposed to dual-frequency magnetic excitation were measured as a function of static magnetic offset field. The Langevin model in thermodynamic equilibrium was fitted to the experimental data to derive parameters of the lognormal core size distribution. These parameters were subsequently used as inputs for micromagnetic Monte-Carlo (MC)-simulations. From the hysteresis loops obtained from MC-simulations, sum-frequency components were numerically demodulated and compared with both experiment and Langevin model predictions. From the latter, we derived that approximately 90% of the frequency mixing magnetic response signal is generated by the largest 10% of MNP. We therefore suggest that small particles do not contribute to the frequency mixing signal, which is supported by MC-simulation results. Both theoretical approaches describe the experimental signal shapes well, but with notable differences between experiment and micromagnetic simulations. These deviations could result from Brownian relaxations which are, albeit experimentally inhibited, included in MC-simulation, or (yet unconsidered) cluster-effects of MNP, or inaccurately derived input for MC-simulations, because the largest particles dominate the experimental signal but concurrently do not fulfill the precondition of thermodynamic equilibrium required by Langevin theory.
Magnetic nanoparticle relaxation in biomedical application: focus on simulating nanoparticle heating
(2021)
Frequency mixing magnetic detection (FMMD) is a sensitive and selective technique to detect magnetic nanoparticles (MNPs) serving as probes for binding biological targets. Its principle relies on the nonlinear magnetic relaxation dynamics of a particle ensemble interacting with a dual frequency external magnetic field. In order to increase its sensitivity, lower its limit of detection and overall improve its applicability in biosensing, matching combinations of external field parameters and internal particle properties are being sought to advance FMMD. In this study, we systematically probe the aforementioned interaction with coupled Néel–Brownian dynamic relaxation simulations to examine how key MNP properties as well as applied field parameters affect the frequency mixing signal generation. It is found that the core size of MNPs dominates their nonlinear magnetic response, with the strongest contributions from the largest particles. The drive field amplitude dominates the shape of the field-dependent response, whereas effective anisotropy and hydrodynamic size of the particles only weakly influence the signal generation in FMMD. For tailoring the MNP properties and parameters of the setup towards optimal FMMD signal generation, our findings suggest choosing large particles of core sizes dc > 25 nm nm with narrow size distributions (σ < 0.1) to minimize the required drive field amplitude. This allows potential improvements of FMMD as a stand-alone application, as well as advances in magnetic particle imaging, hyperthermia and magnetic immunoassays.
The hybrid K+/Ca2+ sensor based on laser scanned silicon transducer for multi-component analysis
(2002)
Purpose — to compare the chemical elemental composition of vitreous cavity content taken from cadaveric eyes compared to samples taken from the eyes with terminal stage refractory glaucoma with decompensated intraocular pressure (IOP). Material and methods. The vitreous contents of the eyes from 2 groups were studied. The 1st group included 15 cadaveric eyes; the 2nd group included 15 eyes with refractory glaucoma in the terminal stage of the disease with decompensated IOP in patients with hypertension pain. The vitreal content samples were taken in the course of antiglaucoma surgery aimed at preserving the eye as an organ and involving employment of drainage in the vitreous cavity. The study of virtual contents was carried out on energy dispersive spectrometer Oxford X-Max 50 integrated into scanning electron microscope Zeiss EVO LS10. Results. Increased concentrations of Kalium and Phosphorus were detected in the vitreous content of cadaveric eyes compared with the vitreal content from the eyes with terminal glaucoma with decompensated IOP taken in vivo (K — 0.172/0.093; P — 0.045/0.025 mmol/L). In the vitreous cavity in the eyes with end-stage glaucoma with decompensated IOP, the concentration of Nitrogen was higher in comparison with human cadaver eyes (2.030/1.424 mmol/L). Conclusion. The increased concentrations of Kalium and Phosphorus in the vitreous content of cadaveric eyes is associated with postmortem autolytic processes and with the release of intracellular content in the destruction of cell membranes. The increased Nitrogen concentration in the vitreal contents of the eyes with terminal stage glaucoma with decompensated IOP may be associated with the presence of osmotically active nitrogen-containing compounds in the eyes with increased IOP.