Read by QxMD icon Read

low frequency ultrasound

Hermes A S Kamimura, Shutao Wang, Hong Chen, Qi Wang, Christian Aurup, Camilo Acosta, Antonio A O Carneiro, Elisa E Konofagou
PURPOSE: Ultrasound neuromodulation is a promising noninvasive technique for controlling neural activity. Previous small animal studies suffered from low targeting specificity because of the low ultrasound frequencies (<690 kHz) used. In this study, the authors demonstrated the capability of focused ultrasound (FUS) neuromodulation in the megahertz-range to achieve superior targeting specificity in the murine brain as well as demonstrate modulation of both motor and sensory responses...
October 2016: Medical Physics
Zhuochen Wang, Karl Heath Martin, Wenbin Huang, Paul A Dayton, Xiaoning Jiang
Techniques to image the microvasculature may play an important role in imaging tumor-related angiogenesis and vasa vasorum associated with vulnerable atherosclerotic plaques. However, the microvasculature associated with these pathologies is difficult to detect using traditional B-mode ultrasound or even harmonic imaging due to small vessel size and poor differentiation from surrounding tissue. Acoustic angiography, a microvascular imaging technique which utilizes superharmonic imaging (detection of higher order harmonics of microbubble response), can yield a much higher contrast to tissue ratio (CTR) than second harmonic imaging methods...
October 20, 2016: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Hamza Ferkous, Slimane Merouani, Oualid Hamdaoui, Christian Pétrier
This work explores the effect of persulfate (PS) on the sonochemical degradation of organic pollutants taking naphthol blue black (NBB), an anionic diazo dye, as a substrate model. The sonolytic experiments were conducted in the absence and presence of PS under various experimental conditions including acoustic power (10-80W), frequency (20 and 585kHz) and saturating gas (argon, air and nitrogen). Experimental results showed that PS decomposition into sulfate radical (SO4(-)) takes place by sonolysis and increasing PS concentration up to 1g/L would result in an increase in the NBB degradation rate...
January 2017: Ultrasonics Sonochemistry
Baharak Sajjadi, Seyedali Asgharzadehahmadi, Perumal Asaithambi, Abdul Aziz Abdul Raman, Rajarathinam Parthasarathy
This paper aims at investigating the influence of acoustic streaming induced by low-frequency (24kHz) ultrasound irradiation on mass transfer in a two-phase system. The main objective is to discuss the possible mass transfer improvements under ultrasound irradiation. Three analyses were conducted: i) experimental analysis of mass transfer under ultrasound irradiation; ii) comparative analysis between the results of the ultrasound assisted mass transfer with that obtained from mechanically stirring; and iii) computational analysis of the systems using 3D CFD simulation...
January 2017: Ultrasonics Sonochemistry
K Shikha Ojha, Timothy J Mason, Colm P O'Donnell, Joseph P Kerry, Brijesh K Tiwari
Fermentation processes involve the participation of enzymes and organic catalysts, generated by range of microorganisms to produce chemical transformations. Ultrasound can be used in such processes to either monitor the progress of fermentation or to influence its progress. High frequency ultrasound (>2MHz) has been extensively reported as a tool for the measurement of the changes in chemical composition during fermentation providing real time information on reaction progress. Low frequency ultrasound (20-50kHz) can influence the course of fermentation by improving mass transfer and cell permeability leading to improved process efficiency and production rates...
January 2017: Ultrasonics Sonochemistry
Sukhvir Kaur Bhangu, Shweta Gupta, Muthupandian Ashokkumar
The production of biodiesel was carried out from canola oil and methanol catalysed by lipase from Candida rugosa under different ultrasonic experimental conditions using horn (20kHz) and plate (22, 44, 98 and 300kHz) transducers. The effects of experimental conditions such as horn tip diameter, ultrasonic power, ultrasonic frequency and enzyme concentrations on biodiesel yield were investigated. The results showed that the application of ultrasound decreased the reaction time from 22-24h to 1.5h with the use of 3...
January 2017: Ultrasonics Sonochemistry
Cheng Liu, Zhen Cao, Jie Wang, Zhehao Sun, Siyuan He, Wei Chen
Ultrasonication pretreatment of raw water with high content of algal cells might cause an increase in dissolved organic nitrogen (DON) and proteins, which must be removed effectively before coagulation. In this study, the efficiency of sonication treatment in removing typical proteins derived from algal cells was investigated by applying ultrasonic waves at 20, 40, 60, 80, and 100kHz, and the influencing factors and removal mechanism were discussed. The results showed that low-frequency sonication could degrade phycocyanin to some extent, achieving about 95% removal rate after 150min of sonication...
January 2017: Ultrasonics Sonochemistry
Cheng Liu, Yakun Sun, Dongying Wang, Zhehao Sun, Ming Chen, Zhi Zhou, Wei Chen
Biological activated carbon (BAC) filter has been widely used as an effective water treatment but regenerations of BAC are costly. Ultrasound has been successfully applied for regeneration of activated carbon but has been less frequently applied to the regenerate the BAC. In this study, bench-scale and pilot-scale experiments were conducted to evaluate the regeneration performance and mechanism of BAC with low-frequency ultrasound. Adsorption indices, microbiological parameters, pore structure and removal efficiencies were further investigated...
January 2017: Ultrasonics Sonochemistry
K Bilmin, T Kujawska, W Secomski, A Nowicki, P Grieb
Sonodynamic therapy (SDT) is a promising technique based on the ability of certain substances, called sonosensitizers, to sensitize cancer cells to non-thermal effects of low-energy ultrasound waves, allowing their destruction. Sonosensitization is thought to induce cell death by direct physical effects such as cavitation and acoustical streaming as well as by complementary chemical reactions generating oxygen free radicals. One of the promising sonosensitizers is 5-aminolevulinic acid (ALA) which upon selective uptake by cancer cells is metabolized and accumulated as protoporphyrin IX...
2016: Folia Neuropathologica
Jürgen Bohlender, Jürg Nussberger, Beate Bohlender
OBJECTIVE: In elderly hypertensive patients, systolic blood pressure (sBP) goals recommended by US and European guidelines (ESH) for the initiation of treatment are more liberal than in younger patients because of an increased risk of treatment-associated side-effects and hypotension. Carotid stenosis increases with age and poses a risk of brain ischemia if hypotension occurs. Its relevance for the routine care of elderly hypertensives, however, remains unclear. We analyzed data on precerebral artery morphology and BP evolution from a survey of aged hospitalized patients...
September 2016: Journal of Hypertension
Georgios Tsivgoulis, Andrei V Alexandrov
PURPOSE OF REVIEW: Low cost, avoidance of irradiation, and high temporal resolution are inherent advantages of ultrasound imaging that translate into multiple clinical uses in many domains of neurology. This article presents clinical uses of ultrasound examination in cerebrovascular, neurodegenerative, and peripheral nervous system diseases. RECENT FINDINGS: Modern treatment and prevention of ischemic stroke rely on prompt diagnosis. Ultrasonography has found a place as a noninvasive screening test and bedside technique that provides estimates of the degree of stenosis as well as hemodynamic and structural information about intracranial and extracranial vessels in real time...
October 2016: Continuum: Lifelong Learning in Neurology
Nathan McDannold, Margaret Livingstone, Can Barış Top, Jonathan Sutton, Nick Todd, Natalia Vykhodtseva
This study investigated thermal ablation and skull-induced heating with a 230 kHz transcranial MRI-guided focused ultrasound (TcMRgFUS) system in nonhuman primates. We evaluated real-time acoustic feedback and aimed to understand whether cavitation contributed to the heating and the lesion formation. In four macaques, we sonicated thalamic targets at acoustic powers of 34-560 W (896-7590 J). Tissue effects evaluated with MRI and histology were compared to MRI-based temperature and thermal dose measurements, acoustic emissions recorded during the experiments, and acoustic and thermal simulations...
October 14, 2016: Physics in Medicine and Biology
Takashi Nishida, Satoshi Kubota, Eriko Aoyama, Nobuyasu Yamanaka, Karen M Lyons, Masaharu Takigawa
OBJECTIVE: CCN family protein 2/connective tissue growth factor (CCN2/CTGF) promotes cartilage regeneration in experimental osteoarthritis (OA) models. However, CCN2 production is very low in articular cartilage. The aim of this study was to investigate whether or not CCN2 was promoted by cultured chondrocytes treated with low-intensity pulsed ultrasound (LIPUS) and to clarify its mechanism. METHODS: Human chondrocytic cell line HCS-2/8, rat primary epiphyseal and articular cartilage cells, and Ccn2-deficient chondrocytes that impaired chondrocyte differentiation, were treated with LIPUS for 20 min at 3...
October 8, 2016: Osteoarthritis and Cartilage
Maria Skytioti, Signe Søvik, Maja Elstad
Intact cerebral blood flow (CBF) is essential for cerebral metabolism and function, whereas hypoperfusion in relation to hypovolemia and hypocapnia can lead to severe cerebral damage. This study was designed to assess internal carotid artery blood flow (ICA-BF) during simulated hypovolemia and noninvasive positive pressure ventilation (PPV) in young healthy humans. Beat-by-beat blood velocity (ICA and aorta) were measured by Doppler ultrasound during normovolemia and simulated hypovolemia (lower body negative pressure), with or without PPV in 15 awake subjects...
October 2016: Physiological Reports
Peter M Narins
Frogs and toads are capable of producing calls at potentially damaging levels that exceed 110 dB SPL at 50 cm. Most frog species have internally coupled ears (ICE) in which the tympanic membranes (TyMs) communicate directly via the large, permanently open Eustachian tubes, resulting in an inherently directional asymmetrical pressure-difference receiver. One active mechanism for auditory sensitivity reduction involves the pressure increase during vocalization that distends the TyM, reducing its low-frequency airborne sound sensitivity...
October 3, 2016: Biological Cybernetics
Omer Aydin, Eli Vlaisavljevich, Yasemin Yuksel Durmaz, Zhen Xu, Mohamed E H ElSayed
We have developed acoustically-activated nanodroplets (NDs) using an amphiphilic triblock copolymer, which self-assembles and encapsulates different perfluorocarbon including perfluoropentane (PFP) and perfluorohexane (PFH). Applying histotripsy waves (i.e. short, high pressure, ultrasound pulses) to solution of PFP- and PFH-NDs generated bubbles clouds at a significantly reduced acoustic pressure compared to the cavitation pressure observed for histotripsy treatment alone. In this report, we summarize the results of combining histotripsy waves at low frequency (345 and 500 kHz) with PFP-NDs and PFH-NDs on the ablation of PC-3 and C4-2B prostate cancer cells...
October 3, 2016: Molecular Pharmaceutics
Visa Suomi, Yang Han, Elisa Konofagou, Robin O Cleveland
Multiple ultrasound elastography techniques rely on acoustic radiation force (ARF) in monitoring high-intensity focused ultrasound (HIFU) therapy. However, ARF is dependent on tissue attenuation and sound speed, both of which are also known to change with temperature making the therapy monitoring more challenging. Furthermore, the viscoelastic properties of tissue are also temperature dependent, which affects the displacements induced by ARF. The aim of this study is to quantify the temperature dependent changes in the acoustic and viscoelastic properties of liver and investigate their effect on ARF induced displacements by using both experimental methods and simulations...
October 21, 2016: Physics in Medicine and Biology
Jeremy S Honaker, Michael R Forston, Emily A Davis, Michelle M Weisner, Jennifer A Morgan, Emily Sacca
The optimal treatment for deep tissue pressure injuries has not been determined. Deep tissue pressure injuries represent a more ominous early stage pressure ulcer that may evolve into full thickness ulceration despite implementing the standard of care for pressure ulcers. A longitudinal prospective historical case control study design was used to determine the effectiveness of non-contact low frequency ultrasound plus standard of care (treatment group) in comparison to standard of care (control group) in reducing deep tissue pressure injury severity, total surface area, and final pressure injury stage...
September 27, 2016: Wound Repair and Regeneration
Wenjing Yang, Yufeng Zhou
Vascular occlusion by the thrombi is the main reason for ischemic stroke and deep vein thrombosis. High-intensity focused ultrasound (HIFU) and histotripsy or microtripsy pulses can effectively dissolve the blood clot with no use of thrombolytic agent and ultrasound contrast agent (microbubbles). In this study, HIFU bursts at the same duty cycle (2%) but varied pulse repetition frequency (PRF) from 1Hz to 1000Hz were delivered to in vitro porcine blood clot for 30s. Thrombolysis efficiency initially increases slightly with the PRF, 86...
September 19, 2016: Ultrasonics Sonochemistry
Salim Elyas, Angela C Shore, Hayley Kingwell, Samantha Keenan, Leigh Boxall, Jane Stewart, Martin A James, William David Strain
OBJECTIVE: Transient ischemic attacks (TIA) and minor strokes are important risk factors for recurrent strokes. Current stroke risk prediction scores such as ABCD2, although widely used, lack optimal sensitivity and specificity. Elevated urinary albumin excretion predicts cardiovascular disease, stroke, and mortality. We explored the role of microalbuminuria (using albumin creatinine ratio (ACR)) in predicting recurrence risk in patients with TIA and minor stroke. METHODS: Urinary ACR was measured on a spot sample in 150 patients attending a daily stroke clinic with TIA or minor stroke...
September 2016: Annals of Clinical and Translational Neurology
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"