INTRODUCTION
Ultrasound represents sound waves with frequencies greater than 16 kHz, higher than that could be heard by human. The upper limit of ultrasonic frequency is usually taken to be 5 MHz for gases and 500 MHz for liquids and solids [1] while the lower frequency limit is considered to be 20 kHz [2]. Ultrasound waves may be divided into two main areas [1, 3], Low Amplitude i.e. the propagation relates to the effect of medium on wave and High Amplitude in which the propagation is due to the effect of the wave on medium.
For many materials, low amplitude propagation has proved to be a powerful analytical technique for investigating the physico-chemical properties [4]. Low power ultrasonic irradiation does not produce any chemical changes, while high power ultrasound instigates permanent physical/chemical changes in the material [3, 5, 6]. High energy input produces cavitation and micro-streaming in liquids, heating, and surface-instability effects at liquid-liquid and liquid-gas interfaces [3, 7, 8].
Ultrasound has provided a method to explore some of primary properties of materials. Sonication offers a much better way to induce these physical and chemical changes with higher efficiencies and shorter processing times. An understanding of mechanisms for different effects of sound is important in connection with its applications in different fields (medicine, food, chemistry). There is considerable need to increase understanding of mechanisms in order to evaluate performances and limitations involved in its various applications.
This study explains the mechanisms of ultrasound irradiation with particular attention in the field of Nanomaterial synthesis.
POWER ULTRASOUND & ITS MECHANISM
Ultrasound waves require physical...
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... as hydroxyl radicals and hydrogen peroxide, which induce drastic reactive conditions in the liquid media [11]. Sonochemistry has various beneficial effects on chemical reactions and processes from the analytical chemistry point of view. Some of which are
• Decrease of reaction time and/or increase of yield
• Use of less forcing conditions e.g. lower reaction temperature
• Possible switching of reaction pathway
• Use of less or avoidance of phase transfer catalysts
• Degassing forces reactions with gaseous products
• Use of crude or technical reagents
• Activation of metals and solids
• Reduction of any induction period
• Enhancement of the reactivity of reagents or catalysts
• Generation of useful reactive species
In this way, ultrasonication remains unique, since no other method of sample treatment can produce such effects [13, 14].
Felder, M. Richard, Elementary Principles of Chemical Processes, 3rd ed.; Wiley: New Jersey, 2000; p 631.
Dai, X., Reading, M., & Craig, D.Q.M. (2008). Mapping Amorphous Material on a Partially Crystalline Surface: Nanothermal Analysis for Simultaneous Characterisation and Imaging of Lactose Compacts. Journal of Pharmaceutical Science, 98, 1499–1510.
Diagnostic medical sonography is a profession where sonographers direct high-frequency sound waves into a patient’s body through the use of specific equipment to diagnose or monitor a patient’s medical condition. As described by the Bureau of Labor Statistics, this examination is referred to as an ultrasound, sonogram, or echocardiogram. The high-frequency sound waves emitted from the handheld device, called a transducer, bounce back creating an echo and therefore produce an image that can be viewed on the sonographers computer screen. This image provides the sonographer and physician with an internal image of the patient’s body that will be used in the diagnosis. The most familiar use of ultrasound is used in monitoring pregnancies and is provided by obstetric and gynecologic sonographers, who also provide imaging of the female reproductive system. Other types of sonography include; abdominal sonography, breast sonography, musculoskeletal sonography, neurosonography and cardiovascular sonography. Due to the vast nature of uses in sonography, most professionals study one field that they choose to specialize in. Diagnostic medical sonography is a rapidly growing field because of the increase in medical advances. The area of Cleveland, Ohio has continued to rise in the medical field with great strides, providing better career prospects with the availability of numerous employment positions.
If you put your finger gently on a loudspeaker you will feel it vibrate - if it is playing a low note loudly you can see it moving. When it moves forwards, it compresses the air next to it, which raises its pressure. Some of this air flows outwards, compressing the next layer of air. The disturbance in the air spreads out as a travelling sound wave. Ultimately this sound wave causes a very tiny vibration in your eardrum - but that's another story.
waves were reflected back to the transducer as they crossed interfaces of different acoustic impedance. More simply, the ultrasound bounced off the
We can draw to a close that the effect of using sound to levitate medicines and liquids can be more a more effective form of giving and creating medicine, because when the amorphous state of medicine touches an object it starts to turn into crystalline state which doesn’t supply as much effectiveness, not only for effectiveness but also in the speed of disbursement. so inturn using acoustic levitation takes out the step that causes it to turn into crystalline state, in turn increasing effectiveness.
The mechanical motions of the ossicles directly vibrate a small membrane that connects to the fluid filled inner ear. From this point, vibration of the connective membrane (oval window) transforms mechanical motion into a pressure wave in fluid. This pressure wave enters and hence passes vibrations into the fluid filled structure called the cochlea. The cochlea contains two membranes and between these two membranes, are specialized neurons or receptors called Hair cells. Once vibrations enter the cochlea, they cause the lower membrane (basilar membrane) to move in respect to the upper membrane (i.e. --the tectorial membrane in which the hair cells are embedded). This movement bends the hair cells to cause receptor potentials in these cells which in turn cause the release of transmitter onto the neurons of the auditory nerve. In this case, the hair cell receptors are very pressure sensitive. The greater the force of the vibrations on the membrane, the more the hair cells bend and hence the greater the receptor potential generated by these hair cells.
A transducer is a mechanism that changes one form of energy to another form. A toaster is a transducer that turns electricity into heat; a loudspeaker is a transducer that changes electricity into sound. Likewise, an ultrasound transducer changes electricity voltage into ultrasound waves, and vice versa. This is possible because of the principle of piezoelectricity, which states that some materials (ceramics, quartz, and others) produce a voltage when deformed by an applied pressure. Conversely, piezoelectricity also results in production of a pressure whe...
Ultrasounds use the same concepts that allow sonar on boats to see the bottom of the o...
Apart of becoming a new patient at a dental office is taking an x-ray and some may have question along with taking an x-ray, like “will I be affected by the x-ray?” or “will I get cancer?”, “how long will it take” “are x-ray’s safe?”, the list goes on and on. So in this paper we will talk about different types of radiation affects such as affects on children and pregnant women as well as some things that may help reduce some of the radiation that may harm the human body.
Polman, H., Orobio De Castro, B. & Van Aken, M. A.G. (2008). Experimental Study of the
Sounds are produced by the vibrations of material objects, and travel as a result of
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
waves are further divided into two groups or bands such as very low frequency (