TY  - JOUR
AB  - Optoacoustic image formation is conventionally based upon ultrasound time-of-flight readings from multiple detection positions. Herein, we exploit acoustic scattering to physically encode the position of optical absorbers in the acquired signals, thus reducing the amount of data required to reconstruct an image from a single waveform. This concept is experimentally tested by including a random distribution of scatterers between the sample and an ultrasound detector array. Ultrasound transmission through a randomized scattering medium was calibrated by raster scanning a light-absorbing microparticle across a Cartesian grid. Image reconstruction from a single time-resolved signal was then enabled with a regularized model-based iterative algorithm relying on the calibration signals. The signal compression efficiency is facilitated by the relatively short acquisition time window needed to capture the entire scattered wave field. The demonstrated feasibility to form an image using a single recorded optoacoustic waveform paves a way to the development of faster and affordable optoacoustic imaging systems.
AU  - Dean-Ben, X.L.
AU  - Özbek, A.
AU  - López-Schier, H.*
AU  - Razansky, D.
C1  - 57296
C2  - 47670
CY  - One Physics Ellipse, College Pk, Md 20740-3844 Usa
TI  - Acoustic scattering mediated single detector optoacoustic tomography.
JO  - Phys. Rev. Lett.
VL  - 123
IS  - 17
PB  - Amer Physical Soc
PY  - 2019
SN  - 0031-9007
ER  - 

TY  - JOUR
AB  - The interaction of magnetic nanoparticles and electromagnetic fields can be determined through electrical signal induction in coils due to magnetization. However, the direct measurement of instant electromagnetic energy absorption by magnetic nanoparticles, as it relates to particle characterization or magnetic hyperthermia studies, has not been possible so far. We introduce the theory of magnetoacoustics, predicting the existence of second harmonic pressure waves from magnetic nanoparticles due to energy absorption from continuously modulated alternating magnetic fields. We then describe the first magnetoacoustic system reported, based on a fiber-interferometer pressure detector, necessary for avoiding electric interference. The magnetoacoustic system confirmed the existence of previously unobserved second harmonic magnetoacoustic responses from solids, magnetic nanoparticles, and nanoparticle-loaded cells, exposed to continuous wave magnetic fields at different frequencies. We discuss how magnetoacoustic signals can be employed as a nanoparticle or magnetic field sensor for biomedical and environmental applications.
AU  - Kellnberger, S.
AU  - Rosenthal, A.
AU  - Myklatun, A.
AU  - Westmeyer, G.G.
AU  - Sergiadis, G.*
AU  - Ntziachristos, V.
C1  - 48208
C2  - 39974
CY  - College Pk
TI  - Magnetoacoustic sensing of magnetic nanoparticles.
JO  - Phys. Rev. Lett.
VL  - 116
IS  - 10
PB  - Amer Physical Soc
PY  - 2016
SN  - 0031-9007
ER  - 

TY  - JOUR
AB  - Microwaves near 42 GHz are found to influence the growth of Saccharomyces cerevisiae. The growth is measured photometrically in stirred aqueous culture. The microwave effect occurs and saturates above a threshold intensity < 10 mW/cm2, excluding any explanation based on microwave heating. A surprisingly strong frequency dependence is observed, with resonances as narrow as 8 MHz. These results confirm the existence of a nonthermal resonant microwave sensitivity in biology; they suggest yet unknown tuned systems triggering yet unknown biological actions.
AU  - Grundler, W.
AU  - Keilmann, F.*
C1  - 34258
C2  - 35328
SP  - 1214-1216
TI  - Sharp resonances in yeast growth prove nonthermal sensitivity to microwaves.
JO  - Phys. Rev. Lett.
VL  - 51
IS  - 13
PY  - 1983
SN  - 0031-9007
ER  - 

TY  - JOUR
AB  - The emission of H+ sputtered from hydrogenated amorphous silicon has been studied for 3- to 30-keV noble-gas-ion bombardment. The results suggest that excited silicon atoms can be emitted as (Si2pH)+ molecules. Auger deexcitation in vacuum results in (SiH)2+ which disintegrates into Si+ and H+ with a corresponding gain in kinetic energy due to Coulomb explosion. Direct emission of H+ is important only at H+ energies > 30 eV or at bombardment energies <3 keV.
AU  - Wittmaack, K.
C1  - 42731
C2  - 40522
SP  - 872-875
TI  - Ionization mechanism of H+ sputtered from hydrogenated silicon.
JO  - Phys. Rev. Lett.
VL  - 43
IS  - 12
PY  - 1979
SN  - 0031-9007
ER  -