Search results for "ultrasonics"

Ultrasound-Guided Intramural Inoculation of Orthotopic Bladder Cancer Xenografts: A Novel High-Precision Approach

2013

Orthotopic bladder cancer xenografts are essential for testing novel therapies and molecular manipulations of cell lines in vivo. Current xenografts rely on tumor cell inoculation by intravesical instillation or direct injection into the bladder wall. Instillation is limited by the lack of cell lines that are tumorigenic when delivered in this manner. The invasive model inflicts morbidity on the mice by the need for laparotomy and mobilization of the bladder. Furthermore this procedure is complex and time-consuming. Three bladder cancer cell lines (UM-UC1, UM-UC3, UM-UC13) were inoculated into 50 athymic nude mice by percutaneous injection under ultrasound guidance. PBS was first injected b…

Biologic effects of ultrasound on liver cells of rat embryos.

1987

Experiments on the biologic effects of ultrasound (US) were carried out on rat embryos exposed for 120 s to a US beam showing features similar to those already employed for diagnostic purposes. Electron microscopic investigation of the liver parenchyma of rat embryos confirmed results obtained from adult guinea pigs with the same duration of exposure, i.e. diffuse vacuolization of cytoplasma and varying degrees of mitochondrial damage.

Assessment of the fundamental flexural guided wave in cortical bone by an ultrasonic axial-transmission array transducer

2013

Abstract The fundamental flexural guided wave (FFGW), as modeled, for example, by the A0 Lamb mode, is a clinically useful indicator of cortical bone thickness. In the work described in this article, we tested so-called multiridge-based analysis, based on the crazy climber algorithm and short-time Fourier transform, for assessment of the FFGW component recorded by a clinical array transducer featuring a limited number of elements. Methods included numerical finite-element simulations and experiments in bone phantoms and human radius specimens ( n  = 41). The proposed approach enabled extraction of the FFGW component and determination of its group velocity. This group velocity was in good ag…

Bioeffects of ultrasound: an experimental study on human embryos.

1991

Abstract The foetuses of 10 women at 9–12 weeks gestation were irradiated with ultrasound under typical diagnostic exposure conditions immediately prior to abortion. Electron microscopy of liver fragments revealed neither morphological nor structural changes.

Size dependence of magnetic domain patterns in exchange-biased Permalloy/NiO microstructures

2002

The magnetic domain structure in Permalloy (Ni81Fe19) micropatterns (10?100??m) on NiO has been investigated by means of soft x-ray photoemission electron microscopy. The exchange anisotropy between the Ni81Fe19 patterns and the NiO layer results in the formation of complex domain structures which markedly differ from the simple Landau?Lifshitz configurations. The domain structures reflect the competition between the exchange anisotropy and the dipole?dipole interaction in a weakly coupled system. The observed domain structures change with the feature size, as the domain patterns lose complexity in the smaller structures.

Compositional dependence of element-specific magnetic moments in Ni2MnGa films

2009

Element-specific magnetic moments were investigated for epitaxial Ni2Mn1+xGa1−x and (Ni2MnGa)1−x(Co2FeSi)x Heusler films using x-ray absorption spectroscopy and x-ray circular magnetic dichroism in transmission. The epitaxial films of the Ni2MnGa-derived compositions were prepared by dc-sputtering on Al2O3 substrates at 773 K. X-ray diffraction confirms a (1 1 0) oriented growth. An increase in the Mn concentration reduces the magnetic spin moment of both Mn and Ni. An increase in the content of Co2FeSi in the Ni2MnGa compound leads to an increase in the Mn and Ni spin moments and to a decrease in Tm for 5% Co2FeSi and finally to a suppression of the phase transition for 20% Co2FeSi. The or…

Dielectric barrier discharge at the triglycine sulfate crystal surface: the role of the electric field of the domain structure

2014

Dielectric barrier discharges (DBD) at the triglycine sulfate crystal surface, generated in air under controlled gas pressure, have been investigated. Electrical characterization of these DBD discharges, produced at temperatures below as well as above the ferroelectric phase transition, are presented. The influence of the electric field of the domain structure on these DBD discharges are discussed in the frame of a model which takes into account the dynamics of the domain structure of the ferroelectric barrier under the action of an external voltage.

Spin transport across antiferromagnets induced by the spin Seebeck effect

2018

For prospective spintronics devices based on the propagation of pure spin currents, antiferromagnets are an interesting class of materials that potentially entail a number of advantages as compared to ferromagnets. Here, we present a detailed theoretical study of magnonic spin current transport in ferromagnetic-antiferromagnetic multilayers by using atomistic spin dynamics simulations. The relevant length scales of magnonic spin transport in antiferromagnets are determined. We demonstrate the transfer of angular momentum from a ferromagnet into an antiferromagnet due to the excitation of only one magnon branch in the antiferromagnet. As an experimental system, we ascertain the transport acr…

Phase Transitions and Electrocaloric Effect in Ca-Modified Na1/2Bi1/2TiO3–SrTiO3–PbTiO3Solid Solutions

2014

Efficient electroluminescence from a perylenediimide fluorophore obtained from a simple solution processed OLED

2009

Simple solution processed organic light emitting diodes are used to screen the performance of two types of highly efficient, narrow band red emitting fluorescent perylenediimides (PDIs). PDIs substituted at the diimide positions seem to form aggregates in the thin film architecture as evidenced by the shifted electroluminescent spectrum. When substituted on the bay position and when used both as the emitting and the electron transporting specie, bright electroluminescence with a narrow width around 610 nm reaching 500 cd m−2 at moderate voltages was observed, demonstrating the usefulness of these fluorophores for OLED applications.