Serwis Infona wykorzystuje pliki cookies (ciasteczka). Są to wartości tekstowe, zapamiętywane przez przeglądarkę na urządzeniu użytkownika. Nasz serwis ma dostęp do tych wartości oraz wykorzystuje je do zapamiętania danych dotyczących użytkownika, takich jak np. ustawienia (typu widok ekranu, wybór języka interfejsu), zapamiętanie zalogowania. Korzystanie z serwisu Infona oznacza zgodę na zapis informacji i ich wykorzystanie dla celów korzytania z serwisu. Więcej informacji można znaleźć w Polityce prywatności oraz Regulaminie serwisu. Zamknięcie tego okienka potwierdza zapoznanie się z informacją o plikach cookies, akceptację polityki prywatności i regulaminu oraz sposobu wykorzystywania plików cookies w serwisie. Możesz zmienić ustawienia obsługi cookies w swojej przeglądarce.
Understanding of the propagation of ultrasound through a bubbly medium is a challenging task because of the nonlinear dynamics of the bubbles and their effect on the attenuation and sound speed of the medium. The majority of the studies on this subject apply linear models, which will generate inaccurate results, especially at higher-pressure excitations. These studies have also ignored the effect...
Parameters derived from the acoustic backscatter coefficient (BSC) represent quantification on an absolute scale and have been used to characterize tissue microstructure. This motivates their use to detect and quantify microstructural remodeling and ripening of the uterine cervix during pregnancy. This work systematically assessed the ex vivo human cervix microstructure and the effects of cervical...
Ultrasound-mediated drug delivery using microbubbles is a growing field with applications ranging from targeted chemotherapy to permeating the blood brain barrier. Despite the potential clinical impact of this technique, the precise parameters needed to reliably induce cell sonoporation, or increased cellular permeability, are not well understood. The goal of this work is to use high frame rate imaging...
It was estimated that annual cost of measurable medical errors was higher than $17 billion in 2008. Phantoms are objects manufactured using a tissue mimicking material (TMM) and largely used to test protocols and mimic clinical environment for medical training. TMM should reproduce at least one biological property to allow the association with clinical situation. The gel made by the copolymer styrene-ethylene/butylene-styrene...
An original method to measure the acoustic properties of porous Pb(Zr0.53Ti0.47)O3 (PZT) backings at high-frequencies (HF, i.e. between 15 and 25 MHz), was developed. To this end, a piezoelectric PZT-based thick film was deposited onto the porous ceramic backing and directly used to generate an acoustic signal in water. Here, the considered signal is the one that was generated in water, reflected...
A noninvasive measurement of in situ acoustic intensity is useful in a variety of therapeutic applications such as ultrasound induced drug and gene delivery. Some previously proposed methods assumed other acoustic parameters such as scattering coefficient to be constant. This paper proposed a method free of such restrictions, by estimating all the relevant parameters using the highly nonlinear behaviors...
The drilling process is generally costly and time consuming and prone to serious hazards. Cost-efficiency and enhanced safety measures are vital for any drilling operation. Recent studies indicate that poor reliability in the drilling process resulted in as much as 30% loss of production time. Improved sensor technology with process automation can improve process performance and safety. During drilling...
Phased array transducers are increasingly prevalent in a therapeutic contex as they facilitate precise control of the beam intensity and focus. To produce enough acoustic energy for ablation, large and costly amplifiers are required. Miniaturised switched circuits provide an alternative that is both more cost effective and more efficient. However, the high Q factor and curved geometry of a therapeutic...
An optical ultrasound generator was used to perform broadband (2–35 MHz) acoustical characterisation measurements of a nanocomposite comprising carbon nanotubes (CNT) and polydimethylsiloxane (PDMS), a composite that is commonly used as optical ultrasound generator. Samples consisting of either pure PDMS or CNT-loaded PDMS were characterised to determine the influence of CNTs on the speed of sound...
In cortical bone, osteoporosis impacts both pore size and porosity. A theoretical model predicting ultrasonic parameters based on cortical micro-architectural parameters remains to be developed, and the independent effect of pore size and porosity on ultrasonic parameters remains unclear. Here, we propose a model predicting the attenuation, phase velocity and scattering mean free path (SMFP) in cortical...
An exhaustive monitoring of an internal sulphate attack of Portland cement-based materials is addressed. Four series of Portland cement mortars with different amounts of gypsum (0%–2% SO3 respect to the cement by mass) were monitored by means of physical and non-destructive tests, studying specimens with a low expansion rate to examine the sensitivity of the applied techniques. The expansion analysis...
Ultrafast, high sensitivity Doppler imaging has led to the development of functional ultrasound (fUS), a novel functional imaging modality for detecting haemodynamic changes in cerebral blood vessels at high spatialtemporal resolution (∼100 μm, ∼1 ms). To allow for this blood tissue signal to be detected the skull either needs to be partially removed or thinned. To overcome this attenuation it has...
Phantoms are objects manufactured using a tissue mimicking material (TMM) and largely used to test protocols and mimic clinical environment for medical training. The TMM should reproduce at least one biological property to allow the association with clinical situation. The gel made by the copolymer styrene-ethylene/butylene-styrene (SEBS) in mineral oil previously reported by our group is a stable...
Surface acoustic waves (SAW) are used to study structural changes induced by electric and weak magnetic fields in the nematic liquid crystal (6CHBT) doped with low concentration (1×10−3, 1×10−4, 1×10−5) of carbon nanotubes, both single-walled (SWCNT), multi-walled (MWCNT) and functionalized with Fe3O4 particles. The role of temperature, concentration and functionalization on structural changes was...
In vivo estimation of attenuation coefficients is useful because of its potential for tissue characterization and relevance in accurate backscatter coefficient estimation. However, current methods based on spectral analysis for ultrasonic attenuation estimation suffer from a severe trade-off between estimation precision and spatial resolution. Recently, the regularized spectral log difference (RSLD)...
Focused ultrasound (FUS) combined with microbubbles (MBs) has been shown to locally and temporarily open the blood-brain barrier (BBB). However, concurrent opening BBB (long pulse) and mapping the location of BBB opening (short pulse) by pulsed-wave excitation always conflicts. Previously proposed passive cavitation imaging in brain suffered from degraded axial resolution because of long driving pulse...
Functional Ultrasound (fUS) has shown to be a promising new neuroimaging modality that uses ultrafast plane waves to detect changes in cerebral blood flow for imaging brain activity at high spatiotemporal resolution. An existing challenge is the ultrasound penetration of skull which decreases with frequency. In the initial study (Macé et al., 2011)[1] a craniotomy was required to perform fUS. Since...
Sulphate attack is considered one of the most aggressive causes of concrete degradation. Ettringite triggers expansion mechanisms that have harmful effects on the Portland cement matrix, causing micro-cracking and, consequently, a reduction in the stiffness and strength of concrete. Portland cement composites are very dispersive and heterogeneous materials that makes very challenging to do non-invasive...
Liver fibrosis is the common result of chronic liver disease. Diagnosis and grading liver fibrosis for patient management is mainly based on blood tests and hepatic puncture-biopsy, which is particularly invasive. Quantitative UltraSound (QUS) techniques provide insight into tissue microstructure and are based on the frequency-based analysis of the signals from biological tissues. This study aims...
The drilling process is generally costly and time consuming and prone to serious hazards. Cost-efficiency and enhanced safety measures are vital for any drilling operation. Recent studies indicate that poor reliability in the drilling process resulted in as much as 30% loss of production time. Improved sensor technology with process automation can improve process performance and safety. During drilling...
Podaj zakres dat dla filtrowania wyświetlonych wyników. Możesz podać datę początkową, końcową lub obie daty. Daty możesz wpisać ręcznie lub wybrać za pomocą kalendarza.