27 research outputs found
Direct observation of the vortex core magnetization and its dynamics
Square-shaped thin film structures with a single magnetic vortex were investigated using a scanning transmission x-ray microscope. The authors report on the direct observation of the vortex core in 500x500 nm(2), 40 nm thick soft magnetic Ni-Fe samples. The static configuration of the vortex core was imaged as well as the gyrotropic motion of the core under excitation with an in-plane alternating magnetic field. This enabled them to directly visualize the direction of the out-of-plane magnetization in the vortex core (up or down). The reversal of the core was effected by short bursts of an alternating magnetic field. An asymmetry appears in the core's trajectory for its orientation pointing up and down, respectively
Species differences in the response of liver drug-metabolizing enzymes to (S)-4-O-tolylsulfanyl-2-(4-trifluormethyl-phenoxy)-butyric acid (EMD 392949) in vivo and in vitro.
Induction of drug-metabolizing enzymes (DMEs) is highly species-specific and can lead to drug-drug interaction and toxicities. In this series of studies we tested the species specificity of the antidiabetic drug development candidate and mixed peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist (S)-4-O-tolylsulfanyl-2-(4-trifluormethyl-phenoxy)-butyric acid (EMD 392949, EMD) with regard to the induction of gene expression and activities of DMEs, their regulators, and typical PPAR target genes. EMD clearly induced PPARalpha target genes in rats in vivo and in rat hepatocytes but lacked significant induction of DMEs, except for cytochrome P450 (P450) 4A. CYP2C and CYP3A were consistently induced in livers of EMD-treated monkeys. Interestingly, classic rodent peroxisomal proliferation markers were induced in monkeys after 17 weeks but not after a 4-week treatment, a fact also observed in human hepatocytes after 72 h but not 24 h of EMD treatment. In human hepatocyte cultures, EMD showed similar gene expression profiles and induction of P450 activities as in monkeys, indicating that the monkey is predictive for human P450 induction by EMD. In addition, EMD induced a similar gene expression pattern as the PPARalpha agonist fenofibrate in primary rat and human hepatocyte cultures. In conclusion, these data showed an excellent correlation of in vivo data on DME gene expression and activity levels with results generated in hepatocyte monolayer cultures, enabling a solid estimation of human P450 induction. This study also clearly highlighted major differences between primates and rodents in the regulation of major inducible P450s, with evidence of CYP3A and CYP2C inducibility by PPARalpha agonists in monkeys and humans
Vortex dynamics in Permalloy disks with artificial defects: Suppression of the gyrotropic mode
The dynamics of magnetic vortices in thin Permalloy disks having artificial defects in the form of small holes at different locations
within the disk has been investigated by means of frequency-domain
spatially resolved ferromagnetic resonance. It is found that the vortex
can be effectively captured by such a defect. Consequently the commonly
observed gyrotropic vortex motion in an applied microwave field of 1 mT
is suppressed. However, if in addition a static magnetic field of at
least 4.3 mT is applied, the vortex core is nucleated from the
artificial defect and a modified gyrotropic motion starts again. (c)
2007 American Institute of Physics
Dielectric and Ferroelectric Properties in Highly Substituted Bi<sub>2</sub>Sr(A)TiNb<sub>2</sub>O<sub>12</sub> (A = Ca<sup>2+</sup>, Sr<sup>2+</sup>, Ba<sup>2+</sup>) Aurivillius Phases
Structure–property
relationships were determined for the
family of three-layer Aurivillius materials Bi<sub>2</sub>Sr(A)TiNb<sub>2</sub>O<sub>12</sub> (A = Ca<sup>2+</sup>, Sr<sup>2+</sup>, Ba<sup>2+</sup>). X-ray and neutron diffraction along with selected area
electron diffraction indicate that Bi<sub>2</sub>SrBaTiNb<sub>2</sub>O<sub>12</sub> crystallizes in the nonpolar <i>I</i>4/<i>mmm</i> space group, whereas the polar <i>B</i>2<i>cb</i> space group best describes Bi<sub>2</sub>SrCaTiNb<sub>2</sub>O<sub>12</sub> and Bi<sub>2</sub>Sr<sub>2</sub>TiNb<sub>2</sub>O<sub>12</sub>. Despite the different space groups, all three compositions
show relaxor behavior as evidenced through <i>P</i>(<i>E</i>) and dielectric measurements. These relaxor properties
are derived from the extensive amount of disorder in each composition
that is found at every cationic crystallographic site and do not depend
on the space group. This disorder is so extensive that it disrupts
the ferroelectric properties allowed by symmetry in the <i>B</i>2<i>cb</i> space group. This work demonstrates the important
role of cation substitution and site disorder in these three-layered
Aurivillius materials and its significant effect on both ferroelectric
and dielectric properties
GFR-estimating models in kidney transplant recipients on a steroid-free regimen
Background. How to best estimate glomerular filtration rate (GFR) in kidney transplant recipients on steroid-free immunosuppression has not been established
Magnetic behaviour of layered Ag(II) fluorides
Fluoride phases that contain the spin-1/2 4d¿9 Ag(II) ion have recently been predicted to have interesting or unusual magnetochemistry, owing to their structural similarity to the 3d¿9 Cu(II) cuprates and the covalence associated with this unusual oxidation state of silver. Here we present a comprehensive study of structure and magnetism in the layered Ag(II) fluoride Cs2AgF4, using magnetic susceptometry, inelastic neutron scattering techniques and both X-ray and neutron powder diffraction. We find that this material is well described as a two-dimensional ferromagnet, in sharp contrast to the high-TC cuprates and a previous report in the literature. Analyses of the structural data show that Cs2AgF4 is orbitally ordered at all temperatures of measurement. Therefore, we suggest that orbital ordering may be the origin of the ferromagnetism we observe in this material
Defining the challenges and opportunities for using patient-derived models in prostate cancer research
Background: There are relatively few widely used models of prostate cancer compared to other common malignancies. This impedes translational prostate cancer research because the range of models does not reflect the diversity of disease seen in clinical practice. In response to this challenge, research laboratories around the world have been developing new patient-derived models of prostate cancer, including xenografts, organoids, and tumor explants. Methods: In May 2023, we held a workshop at the Monash University Prato Campus for researchers with expertise in establishing and using a variety of patient-derived models of prostate cancer. This review summarizes our collective ideas on how patient-derived models are currently being used, the common challenges, and future opportunities for maximizing their usefulness in prostate cancer research. Results: An increasing number of patient-derived models for prostate cancer are being developed. Despite their individual limitations and varying success rates, these models are valuable resources for exploring new concepts in prostate cancer biology and for preclinical testing of potential treatments. Here we focus on the need for larger collections of models that represent the changing treatment landscape of prostate cancer, robust readouts for preclinical testing, improved in vitro culture conditions, and integration of the tumor microenvironment. Additional priorities include ensuring model reproducibility, standardization, and replication, and streamlining the exchange of models and data sets among research groups. Conclusions: There are several opportunities to maximize the impact of patient-derived models on prostate cancer research. We must develop large, diverse and accessible cohorts of models and more sophisticated methods for emulating the intricacy of patient tumors. In this way, we can use the samples that are generously donated by patients to advance the outcomes of patients in the future.</p