Ultrasound-Assisted Extraction of Bioactive Compounds from Microalgae
Gokare A. Ravishankar, Ranga Rao Ambati in Handbook of Algal Technologies and Phytochemicals, 2019
Ultrasound waves are high frequency sound waves, which are above the human hearing capacity to perceive (Kadam et al. 2013). The main difference between ultrasound, sound and infrasound is the wave’s frequency. Sound waves that are at human hearing frequencies range from 16 Hz to under 20 kHz, while ultrasound waves have frequencies ranging from 20 kHz to 10 MHz, over the human hearing range but below microwave frequencies, and the infrasound wave frequencies are below 16 Hz (Chemat et al. 2011; Pico 2013). Ultrasound waves are characterized by their frequency and wavelength, and the mathematical product of these two parameters results in the wave speed through the medium (Figure 8.1). In addition, ultrasound wave intensity or amplitude is also an important parameter and is used to classify the industrial application. The intensity of an ultrasound wave is defined as the amount of energy passing through the unit cross-sectional area perpendicularly to the beam per unit time at that point, and it is measured in watts per square centimetre (W/cm2) (Hendee & Ritenour 2003). The frequency of ultrasound exerts significant influences on the extraction yield and kinetics.
Introduction
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha in Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
Unlike X-ray energy, ultrasound is not electromagnetic radiation. Ultrasound is very similar to audible sound, although of a much higher frequency. It is a form of energy that travels in waves, propagated by vibration of adjacent molecules in a medium. The use of ultrasound for imaging is relatively simple technology. A pulse of sound is generated within a transducer – a device that can change one form of energy into another. The sound is transmitted into the body and propagated through the tissues, with gradual attenuation by absorption and reflection. Although some sound is reflected away and scattered, some is reflected back to the transducer as an echo, and this can be plotted on a screen as a dot whose brightness is related to the strength of the returned echo, and whose location is calculated by a system known as registration, so that the display replicates the position in the body.
Bioengineering Aids to Reproductive Medicine
Sujoy K. Guba in Bioengineering in Reproductive Medicine, 2020
Ultrasound at the energy levels prevalent in diagnostic medicine is generally considered “safe” because so far no ill effects which can be specifically related to the ultrasonic energy exposure have been reported. However, ultrasonic waves can have definite biological effects at higher intensities and so safety involves quantification of the exposure level and is not absolute. Current trend is not only toward carrying out ultrasonic procedures on more people but also to an increase in the frequency of ultrasonography done on an individual. In fact, there are proposals to make ultrasonic monitoring a routine in the management of all pregnancies. Under these circumstances it cannot be ruled out that harmful effects not seen earlier may in the future become apparent. The situation demands that all biomedical personnel in any way connected with diagnostic ultrasound be aware of the safety aspects and always be watchful about deleterious effects of ultrasound in those undergoing the procedures. At the same time, there is no reason to avoid the use of ultrasound wherever it is really required.
The effect of ultrasound or phonophoresis as an adjuvant treatment for non-specific neck pain: systematic review of randomised controlled trials
Published in Disability and Rehabilitation, 2022
Kinley Dorji, Nadine Graham, Luciana Macedo, Janelle Gravesande, Charles H. Goldsmith, Geoffrey Gelley, Maureen Rice, Patricia Solomon
Therapeutic ultrasound is a common therapeutic modality often used in conjunction with exercise or manual therapy to treat various musculoskeletal conditions, including neck pain. Ultrasound is defined as a “sound wave or pressure wave with a frequency above the limit of the human hearing (16 to 20 kHz)” [9, p 410]. Therapeutic ultrasound used in rehabilitation treatments utilises frequencies within 1–3 MHz with intensities of 0.1–2.0 W/cm2 [9]. Ultrasound at 1 MHz can penetrate deep into the tissues from 2 to 4 cm, while ultrasound at 3 MHz has been demonstrated to penetrate 1–2 cm [10]. The two theories explaining the biophysiological effect of ultrasound include thermal and non-thermal effect theory [11]. However, it is difficult to separate the therapeutic effects caused by ultrasound into thermal and non-thermal as these coexist as the application of ultrasound on tissues continually produces mechanical and thermal effects. Thermal effects are generally used to manage pain, muscle spasm, and improve connective tissue disorders in sub-acute and chronic conditions [9,12]. Non-thermal effects are typically used in acute conditions to manage pain, reduce oedema and to stimulate tissue repair [12]. Overall, the thermal and non-thermal effects promote healing of the tissues and control pain which would theoretically result in reduced pain and improved function and disability during both acute and chronic stages
Development of modified RSA algorithm using fixed mersenne prime numbers for medical ultrasound imaging instrumentation
Published in Computer Assisted Surgery, 2019
Seung-Hyeok Shin, Won Sok Yoo, Hojong Choi
Ultrasound is used in a variety of applications such as medical diagnostics and therapy, non-destructive testing, and sound navigation and range [1–3]. In particular, medical ultrasound imaging is a non-invasive and inexpensive technique compared to X-ray, computed tomography, and positron emission tomography [4,5]. Owing to the developments in the semiconductor industry, medical ultrasound imaging instrumentation has been widely used for cost-effective diagnostic solutions [6,7]. Therefore, ultrasound imaging is one of the most useable medical techniques that can be used for direct on–site diagnosis in emergency rooms, as well as an off–site diagnostic tool in ambulances; however, diagnosis in an ambulance increases the chance of invasion of patient information [8,9]. Therefore, encrypting patient information has become important in medical ultrasound instrumentation to secure this information when images are accessed off site.
Recent advances in ultrasound-triggered therapy
Published in Journal of Drug Targeting, 2019
Chaopin Yang, Yue Li, Meng Du, Zhiyi Chen
The diagnostic ultrasound is widely available in clinical use because the ultrasound is relatively inexpensive and safe. And recently contrast-enhanced ultrasound (CEUS) were approved to use for detection and characterisation of malignant focal liver lesions with high diagnostic accuracy by FDA [161]. The FDA also approved an ultrasound contrast agent Lumason® for intravenous and intracavitary administration in children for assessment for vesicoureteral reflux with contrast-enhanced voiding urosonography. But research indicated that lack of expertise and training were still the main barriers [162]. In addition to diagnostic function, ultrasound is increasingly being used for therapeutic applications. In 2004, the FDA has already approved that MRgFUS/MR-HIFU could be used for the thermal treatment of uterine fibroids, offering the doctor and the patients an option of minimally invasiveness method. But the guidelines declared those with extensive scars in the lower abdominal wall are not considered for such application due to the high risk of thermal damage to the skin. The FDA has also approved the first MRI-FUS device to treat essential tremor in patients who have not responded to medication, which could help patients enjoy a better quality of life but not a cure recently. But some side effects were also needed to pay attention, such as numbness/tingling of the fingers, headache, skin burns with ulceration of the skin, scar formation and blood clots. Therefore, patients who received such treatment should be strictly obeyed these regulations [163].
Related Knowledge Centers
- Bone Conduction
- Cochlea
- Middle Ear
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- Hearing Range
- Sonochemistry
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- Nocturnality
- Ultrasound Avoidance