Search results for "Ultra"

Dynamical amplification of electric polarization through nonlinear phononics in 2D SnTe

2020

Ultrafast optical control of ferroelectricity using intense terahertz fields has attracted significant interest. Here we show that the nonlinear interactions between two optical phonons in SnTe, a two-dimensional in-plane ferroelectric material, enables a dynamical amplification of the electric polarization within subpicoseconds time domain. Our first-principles time-dependent simulations show that the infrared-active out-of-plane phonon mode, pumped to nonlinear regimes, spontaneously generates in-plane motions, leading to rectified oscillations in the in-plane electric polarization. We suggest that this dynamical control of ferroelectric material, by nonlinear phonon excitation, can be ut…

Ultrasound assisted reductive cleavage of eudesmane and guaiane γ-enonelactones. Synthesis of 1α,7α,10αH-guaian-4,11-dien-3-one and hydrocolorenone f…

2001

Abstract Ultrasound enhances the rate of reductive cleavage of the C6–oxygen bond of sesquiterpene enonelactones. trans-Eudesmanolides 1c–1g, cis-eudesmanolides 2a–2c, and trans-guaianolides 4a–4d react with Zn in acetic acid–H2O under sonochemical conditions to afford the corresponding sesquiterpene acids 3a–3g and 5a–5d, respectively in good yields. Starting from 5d two natural guaianes 1α,7α,10αH-guaian-4,11-dien-3-one (6) and hydrocolorenone (7) have been prepared in good yields through a straightforward sequence.

ChemInform Abstract: Ultrasound-Assisted Reductive Cleavage of Eudesmane and Guaiane γ-Enonelactones. Synthesis of 1α,7α,10αH-Guaian-4,11-dien-3-one …

2010

Abstract Ultrasound enhances the rate of reductive cleavage of the C6–oxygen bond of sesquiterpene enonelactones. trans-Eudesmanolides 1c–1g, cis-eudesmanolides 2a–2c, and trans-guaianolides 4a–4d react with Zn in acetic acid–H2O under sonochemical conditions to afford the corresponding sesquiterpene acids 3a–3g and 5a–5d, respectively in good yields. Starting from 5d two natural guaianes 1α,7α,10αH-guaian-4,11-dien-3-one (6) and hydrocolorenone (7) have been prepared in good yields through a straightforward sequence.

ChemInform Abstract: Ultrasound-Assisted Reductive Cleavage of Sesquiterpene γ- Enonelactones.

2010

Abstract Ultrasound enhances the rate of reductive cleavage of the C 6 -oxygen bond of several cis - and trans - sesquiterpene γ-enonelactones. Interestingly ultrasound overrides the stereoelectronic requirements for the reductive cleavage of the most usually occurring sesquiterpene trans -lactones.

Segmentation d'images robuste appliqué à l'imagerie par résonance magnétique et l'échographie de la prostate

2012

Prostate segmentation in trans rectal ultrasound (TRUS) and magnetic resonanceimages (MRI) facilitates volume estimation, multi-modal image registration, surgicalplaning and image guided prostate biopsies. The objective of this thesis is to developshape and region prior deformable models for accurate, robust and computationallyefficient prostate segmentation in TRUS and MRI images. Primary contributionof this thesis is in adopting a probabilistic learning approach to achieve soft classificationof the prostate for automatic initialization and evolution of a shape andregion prior deformable models for prostate segmentation in TRUS images. Twodeformable models are developed for the purpose. An…

A linear generator for a waveroller power device

2017

In this paper experimental tests on a small scale tubular linear generator to be applied to wave rollers device are presented. A reduced scale of gnerator is presented and experimental results obtained in on test bench are shown. Experimental waveforms of current and voltage are recorded. Simulation results are compared to the experimental ones in order to validate the mathematical models used.

Effects of network pressure on water meter under-registration: an experimental analysis

2018

Abstract. In water supply systems, a considerable amount of apparent loss is caused by meter under-registration. Water meters are subject to intrinsic systemic error depending on the actual flow rates passing through them. Furthermore, the moving parts of the meter are subject to wear and tear that progressively reduce meter accuracy. The increase in systemic error is especially evident at low flow rates because of growing friction in the rotating mechanism, which requires a higher flow to start the meter (starting flow). The aim of this paper is to experimentally investigate metering error in an attempt to find a direct link between meter age, network pressure and apparent losses caused by…

Early stages of test formation in larva of Ascidia malaca (Tunicata, Ascidiacea): ultrastructural and cytochemical investigations.

2003

Abstract The swimming larvae of ascidians are entirely covered by a hyalin coat called tunic, or test. This covering consists of two cuticular layers, C 1 and C 2 , which surround an inner compartment composed of an amorphous hyalin matrix with numerous fibrils dispersed inside. Data from the literature agree on the key role played by the cells of the larval ectodermic layer in the synthesis and secretion of larval test components. In the present article are reported ultrastructural and cytochemical investigations made during test formation in the swimming larva of Ascidia malaca . Besides confirming the role played by ectodermic cells during the early stages of test formation, the investig…

Magnetic Resonance Imaging and Ultrasound Evaluation after Breast Autologous Fat Grafting Combined with Platelet-Rich Plasma

2014

Interventistica eco-guidata per l’articolazione d’anca

2013

Lo scopo di questo lavoro è di rivedere le principali applicazioni della interventistica eco-guidata d’anca, descrivendone le indicazioni e la metodologia. L’ecografia è una metodica considerata sicura per i pazienti, in quanto non è stato dimostrato un possibile danno dovuto all’energia trasmessa dagli ultrasuoni ai tessuti del paziente, contrariamente alle metodiche che fanno uso di radiazioni ionizzanti, come la radiografia convenzionale e la tomografia computerizzata. Inoltre, l’ecografia risulta rapida ed efficace nel guidare l’ago verso la sede voluta evitando di intercettare strutture vascolari e/o nervose, consentendo quindi una maggiore sicurezza, rispetto alle tecniche interventis…