August 8, 2014
Huge steps were made today! Once a 100 mh inductor was placed into the circuit and a basic sweep was completed, a small buzzing sound could be heard emitting from the PZT microphone at the bottom of the flask! This indicates that a bubble within the flask responded to the frequency it was being bombarded with and responded to the signal. When the flask was titled at certain angles, this buzzing sound got smaller or louder. At one angle in specific, I was able to see a bubble hovering near the edge of the flask and jiggling. Once the tilt was altered, the bubble would stop. This semi-trapping of the bubble would end after about 30 seconds.
I graphed the resonance for the circuit. The results follow:
The resonance frequency for the circuit seemed to be 23640 hertz, not far in range for the flask's resonance of 24480 hertz. When this frequency was reached, the loudest buzzing was heard. I decided to momentarily stop the oscilloscope to get a picture of a still signal. The picture shows evidence that the caught bubble is emitting an additional frequency to the one sent it as indicated by the additional waves upon the larger ones. This is what is typically picked up around sonoluminescence, however, sonoluminescence has not been achieved because the inductance has not yet been altered to the system.
Picture of oscilloscope signal:
August 7, 2014
This morning I was able to complete graphing the resonance curve for the acoustic mode. The results were completely different from any resonance I had previously graphed. I placed a line fit upon the graph so that the resonance frequencies could be better observed.
The acoustic resonance that sonoluminescence is supposed to take place at occurs at the first mode. Since the first resonance peak contains the least number of irregularities, this seems to correspond with the first mode. The resonant frequency for the first mode was determined to be 24480 hertz. As the frequencies continued to increase, each resonance frequency seemed to have at least two peaks. The higher the resonant frequencies seemed to go, the more irregularities there seemed to be. However, each resonant curve seemed to experience a sharp drop before and a higher value after.
With over 4 resonance peaks, there are more than 4 resonant modes belonging to the acoustic system. This shows evidence that modes are definately varied by small alterations to shape, hence making determining resonance for unusual shapes difficult. I want to do a further investigation to determine if I can make better estimations for resonance frequncies using specifically known flask dimensions.
Once the acoustic resonance of the flask was determined, I decided to determine the resonance of the circuit. I placed a known inductor into the circuit with a value around 100 mh. When the acoustic resonance frequency is determined, tbe capacitance of the PZTs as they act as capacitors can be determined. With this value, the needed inductance for the circuit can be determined to alter the resonant frequency of the circuit to the resonant frequency of the spherical acoustic mode. Once this is completed, energy traveling from capacitor to capacitor should maximize over the 1000 volts required for sonoluminescence.
August 6, 2014
Today I decided to investigate the acoustic resonance of the flask. The flask being used specifically within this experiment is a 125 ml flask that is 6 cm in diameter with a flat bottom. This flask shape will hopefully alter the number of acoustic modes in the system. A typical spherical flask is known for 3 modes while a rectangular flask has 4, hence different numbers of resonant frequencies. By the unique shape of the flask, the number of resonant frequencies will hopefully be altered. In order to complete this task, I set up my spherical flask in a circuit with no inductors or resistors and then began plotting the acoustical resonance, which I will hopefully finish tomorrow. This specific graph took me much longer than the three previous resonance curves due to the number of points plotted and the unique characteristics of the resonance curves.
August 5, 2014
For my second circuit with 10 mh inductor and 1 volt of power being sent through the system, the resonance curve is as follows:
I then completed another resonance curve with 100 mh inductor and 1 volt of power. The resonance curve is shown as follows:
Both of these graphs follow the same pattern as the first where the leading side is typically lower than the side following the resonance curve. Since the last two graphs had the same voltage within the circuit and the only factor adjusted seemed to be the inductance, the results show that the inductance has an impact on the resonance frequency of the circuit. A higher inductance seemed to have a smaller resonant frequency within this specific LRC circuit. The two circuits with the same voltage placed in also had similar Peak to Peak voltages as shown by the graph.
I began to study LRC resonance and its relation to the numerical values of inductance and capacitance.
August 4, 2014
Using the circuit made previously, I created a resonance curve for the 1 mh and the .1 v.
As this was my first attempt, there were more points closer to the resonance frequency. The graph follows a pattern where the Peak to Peak voltage is lower before the resonant curve and higher after. This is due to the fact that the Peak to Peak should hit 0 volts when no frequency is applied. However, if noise is within the system, the voltage of the noise will be the first voltage picked up by the system even due to the fact that outside frequencies are impacting the system.
I began work on the second circuit. This circuit followed the same basic set up as the first however, the inductance was changed to 10 mh and 1 volt. The voltage was adjusted due to its inability to be displayed on the oscilloscope with .1 volts.
August 1, 2014
Today I set up the test circuit to see if I could find the capacitance of a known capacitor when the inductance and other factors are known. The circuit was a basic LRC circuit with an audio amplifier, an inductor, a capacitor, a 1 ohm resistor and a oscilloscope. It was based off a lab that Libby completed during a semester at Stony Brook.
I made a circuit schematic of my circuit below using http://www.docircuits.com/circuit-editor.
Note that the frequency of the function generator constantly changed in order to find the resonant frequency of the system and that the voltage produced from the function generator was eventually changed to .1 volt in order for the display to be picked up neatly by the oscilloscope.
I began to plot the resonance curve and got a basic idea of the resonance frequency based off the amplitude of the oscilloscope signal. It was around 145070 Hz. Further work will be continued on Monday to map out the resonance curve with more data points.
An image of the circuit:
July 31, 2014
My sonoluminescence set up was taken from the school and partially set up today. I am pleased to say all of the wires are still soldered in place and there is still conductance, allowing electrical flow throughout the system. My inductor will be replaced with an adjustable coil tuned to the system's inductance.
I had a discussion with Dr. Noe about my incorrect glue use on the system. The type I used unfortunately partially blocks the propagation of sound waves. This is a limitation to my device, however, it will work none the less as indicated by the signal picked up by the microphone transducer on the bottom of the flask.
July 30, 2014
Today began with adjusting our presentations for progress made with out projects. I believe that my presentation went well; I was able to discuss the multiple mode theory of the spherical system.
My project as a whole will delve into using physics to explain the occurance of sonoluminescence. In addition to investigating the acoustic resonance of a system, I plan to investigate the LRC circuit as well. When the resonant frequencies of acoustics and circuit match, the greatest vibrations occur within the system. This provides the ideal conditions for sonoluminescence.
To make the frequencies match, an inductance must be imposed on the system to lower the resonant frequencies of the circuit as created by the capacitors. The capacitors in the system are the piezo-electric transducers (PZT). I plan on using Rachel Ruch's paper to guide me in this process. Rachel was a past LTC undergrad student. Her methods will help me to determine the required inductance and alter the coil owned by Dr. Noe based off my 125 ml flask with a resonant frequency of 24.5 kilohertz.
Rachel's paper: http://laser.physics.sunysb.edu/~rachel/paper/paper.pdf
July 29, 2014
The idea of multiple modes within a system is supported by work done by past students at the LTC. Several of these students picked up multiple resonant frequencies when commiting a wide enough sweep.
Upon further investigation, a presentation by Kenneth Bader, a graduate student at the University of Mississipi, was found. His project determined the resonant frequencies belonging to three seperate modes within a spherical flask. Within his presentation, he also indicated that the resonant frequencies can be predetermined by applying the spherical Bessel function to the Helmholtz equation. K represents the wavenumber of a function while ∇ represents the gradient determined by utilizing the radius of the flask within the spherical wave equation.
Link to Kenneth Bader's presnetation: http://www.phy.olemiss.edu/Colloquia/Bader_talk.pdf
This formula requires calculus knowledge beyond my current scope, so Libby extended my knowledge on the subject. A big thank you to Libby (if she ever reads this)!
July 28, 2014
Used the wave equation to determine the radius of the flask. The wave equation states that V = λf. For my sonoluminescence flask, the resonance frequency when sweeping the oscilloscope was determined to be 24.5. Coupled with the fact that the speed of sound in water is 1497 m/s, the wavelength was determined to be 6.1 centimeters, making the radius of the flask 3.05 centimeters.
This was compared to the radius determined with the volume for a sphere. V = 4/3 π r3 was used in which 125 ml was converted to 125 cm3. The radius with this equation was determined to be 3.1 centimeters, pretty close to the 3.05 calculated using the wave equation.
However, I ran into a problem with these calculations when investigating modes. Sonoluminescence is known for occuring with the first mode. The problem with this fact is that the wave equation assumed that the diameter of the sphere was equal to one wavelength. However, the diameter of the sphere for the first mode when a frequency propagates at a straight course, would be half of a wavelength. This indicates that there may be exceptions with the propagation of a wave within a sphere due to its shape.
July 24, 2014
Laser diffraction scattering can also be applied to particle movements within an evaporating drop of liquid. As particles move over time, there will be different areas of light intensity due to different thicknesses over the liquid droplet. This means that a videotaped diffraction pattern could be used to show particle patterns resulting from liquid dynamics over a period of time.
Liquid fluid dynamics in a water droplet has multiple practicle applications. For example, when a coffee ring evaporates, its particles tend to clump along the edges in size order. This is due to the fact that their shapes are spherical. Typical particles are olong, allowing them to clump in the middle of the particle and prevent liquid flow.
Although this effect is most common in coffee, it also takes place in jet ink printer drops. This causes the buildup of ink particles, increasing price of the process itself, and decreasing the capability of the machine.
This is an example where particle observation using this technique can be utilized. Different thicknesses in the particle clumping can be observed using the intensity levels from the diffraction patterns.
Diffraction patterns within bacterial colonies over period of time: http://www.opticsinfobase.org/view_article.cfm?gotourl=http%3A%2F%2Fwww%2Eopticsinfobase%2Eorg%2FDirectPDFAccess%2F19F6C9DA-A694-BF08-26FE2E298FBEE0D8_223746%2Foe-19-22-21768%2Epdf%3Fda%3D1%26id%3D223746%26seq%3D0%26mobile%3Dno&org=
Intensity measurements using ImageJ: http://www.unige.ch/medecine/bioimaging/tricks/imagejtutorials/Quantification.pdf
Basic introduction to Rayleigh scattering when applied to water droplets within atmosphere: http://www.chm.bris.ac.uk/~chswp/Scattering/lecture02.pdf
July 23, 2014
Today I tried to look into light scattering as an aspect of sonoluminescence. During my research, I found an application of interference within a diffraction pattern toward particle sizes.
The basic set up of Laser Diffraction method:
Basic set up image from: http://pssnicomp.com/glossary/laser-diffraction/
A HeNe laser is typically used to send a beam to a lens which converges the beam to a point. A sample of particles is then placed at the point. The laser beam hits a single particle and scatters at different angles. Typically, the larger the angle the smaller the particle and vice versa.
Particle size is determined by the different intensities shown within the diffraction pattern. Mie scattering describes the scattering of electromagnetic radiation (or intensity) by a particle that is spherical in shape. Rayleigh scattering, which follows the same basic concept as Mie, can be used to discover the radius of a spherical particle based off light interference intensities. Rayleigh specifically describes interaction between a particle smaller than the laser beam's wavelength and the laser beam itself.
I = intensity of scattered beam after hits particle
Io = Intensity before beam hits particle
Θ = scattering angle
R = distance from scatter
λ = wavelength
n = refractive index
d = diameter of sphere
When bacteria form, they form in unique patterns. This grouping of bacteria cause interesting diffraction patterns.
Diffraction pattern of Salmonella enteritidis colony made by Igor Buzalewicz and associates:
This paper specifically observed bacterial growth and depletion due to different conditions.
Link to paper titled the Influence of various growth conditions on Fresnel diffraction patterns of bacteria colonies examined in the optical system with converging spherical wave illumination: http://www.opticsinfobase.org/view_article.cfm?gotourl=http%3A%2F%2Fwww%2Eopticsinfobase%2Eorg%2FDirectPDFAccess%2FF0A32226-DEC4-2922-CB8D2BAFD9773622_223746%2Foe-19-22-21768%2Epdf%3Fda%3D1%26id%3D223746%26seq%3D0%26mobile%3Dno&org=
The intensity pattern of these kinds of bacterial colonies would have multiple intensity peaks. For each intensity peak, the diameter would be the diameter of the multitude of particles in that area. If the diameter for multiple cells was divided by the diameter of a single bacterium, the number of bacteria for that intensity can be found. If this is done across the entire bacteria colony, an estimation on the number of bacteria can be made. This can be used for indentifying the level of contamination of a sample.
July 21, 2014
Oscilloscopes pick up sound waves. The intensity of a sound wave is equal to the value of the amplitude of the sound wave squared. The resulting unit is watts per meter squared.
To convert watts per meter squared into decibals, the intensity must be plugged into:
Once in decibals, the formula below can be used to find pressure. P represents the pressure from the sound wave while Po represents the threshold pressure of hearing.
Liquid liquid interface article: http://www.researchgate.net/publication/228335370_Passage_of_a_Gas_Bubble_through_a_Liquid-Liquid_Interface
July 18, 2014
Today I worked on updating my journals. I needed to explain my proposals from Wednesday's presentation and update the work we had done with Rayleigh's Criterion.
I also looked into information regarding acoustic cavitation in the medical field. Acoustic cavitation is used in extracorporeal shock wave lithotripsy in which cavitation helps to break up kidney stones. Additionally, current research is going on to determine if caviation can be used to deform blood clots.
However, I did find a negative application of acoustic cavitation. If ultrasound pulses are sent incorrectly, they can find a bubble in a different area of the body. This is problematic due to the fact that enough power in the cavitation site can also cause the collapse of blood veins.
July 17, 2014
Rayleigh's Criterion allows a person to find specific information about a circular aperture including its diameter, the angular resolution, and the wavelength of the wave sent through the aperture.
We did a miny experiment in which we created different diffraction patterns using a HeNe laser and three different apertures: a circle, a square, and a triangle. The square and triangle could not be applied towards Rayleigh's Criterion.
We were suprised to find that the triangle created six diffraction paths. Although a triangle is a different shape than a hexagon, from the six paths we were able to determine that they would have the same diffraction pattern.
Next we used dimensions from the laser configuration in order to determine the wavelength of the laser with Rayleigh's Criterion. Using tangent, we were able to determine that the angular resolution angle was approximately 3.75x10-3. Due to the small angle approximation, this was the assumed value for sin theta. The distance was determined to be 200x10 -6m. When these values were plugged into the equation our final wavelength value was 615 nm in comparison to the actual value of 632 nm.
July 16, 2014
Today we presented project proposals. Dr. Noe suggested that my project should involve taking a small aspect of something and investigating the physics behind it. He said that learning why something happens is as important as the result itself.
Taking his advice, I proposed two different ideas for my presentation. My first idea was applying the principles of the piezo electric water device towards acousto-optic modulators (AOMs) due to the fact that the differences in the two lie in the material in which the density is being changed (the water vs. the crystal).
The second idea I proposed involves a further understanding of acoustic cavitation within a sonoluminescence bubble. I came across Hele-Shaw Cell from an Amateur Scientist article written by Jearl Walker that allows its user to observe cavitation or bubble interaction with different densities.
From my understanding of the water device that can be applied to AOMs, I know that acoustic waves cause strips of pressure within liquid. Between these pressure strips, there are normal pressure levels. This is what causes the periodic growth and depletion known as acoustic oscillation.
However, learning about the use of the water device also taught me that increasing pressure also changes density. A buoyant force can be applied when liquid forces oppose the force of gravity for a submerged object. Buoyant force is equal to pressurexgravitationalconstantxvolume. If the buoyant force remains the same, as pressure inceases, volume must decrease. A decrease in volume signals an increase in density of the water as mass remains the same.
The connection between the Amateur Scientist article and these formulas involves the change in density related to pressure. If the amount of pressure increased by a sound wave at a resonance frequency can be determined, then the change in density can be discovered. A change in density within the device can be created by placing different liquids with the specific density difference within the device.
This device would allow the modeling of bubble change as it moves between densities when oscillating. Since cavitation itself occurs at too fast a rate for this interaction to be observed, this application would allow insight into the specific reaction of the bubble interface to density change.
Amateur Scientist Hele-Shaw Cell:
Amateur Scientist article: http://www.nature.com/scientificamerican/journal/v261/n4/pdf/scientificamerican1089-116.pdf
July 15, 2014
The American Journal of Physics article concentrated on sending a laser beam through the test tube with the piezoelectic in which the test tube would obtain the same qualities as a lens (diagram shown below).
I decided to do some basic research on lenses. Upon my research, I stumbled upon several interesting formulas that calculate the focal length based off the index of refraction. Since the index of refraction changes due to acoustic pressure in the device, I am curious to see how the focal length would be altered with these changes.
The formula listed below is known as the Lens Maker's Formula. It shows that the higher the index of refraction, the lower the focal length of the lens.
Len's Maker Formula source: http://scienceworld.wolfram.com/physics/LensMakersFormula.html
When looking at the diagram of the converged rays resulting from the test tube, I realized that the image reminded me of the rays that converge within an eye at the focal point. When an eye has perfect vision, the focal point of the eye focuses at the eye's retina. A focal point resting closer or farther than the retina results in a blurred image. I found a diagram displaying this information:
Diagram source: http://www.patient.co.uk/doctor/refraction-and-refractive-errors
Next, I remembered a conversation the group had with Dr. Noe in which we discused dioptres, a unit of measurement for glasses. I began to wonder what exactly a dioptre is and if it relates to focal length. A dioptre is used to explain how powerful a lens is. It is equal to the reciprocal of the focal length in meters.
If the index of refraction can be used to change the focal length, can the changing index of refraction be used to allow the focal point to rest on a certain point, for instance eye retina? And if that is the case, could this idealogy be used as glasses lenses that could be altered whenever a person is in need of a new prescription?
However, when I talked to Dr. Noe about this idea, he found several flaws upon this use of changed indices. Due to the fact that light would only be refracted in one direction, this use would not be recommended. Additionally, the light is sent through a test tube with a round body, hence not using the typical lens configuration which may be a problem in terms of formula use. He also mentioned that the changes in density due to sound pressure for this type of device would be very tiny, hence most likely not powerful enough to create a substantial change in focal length.
July 14, 2014
We started off the morning talking about interests for possible topics. It was determined that I should try to persue something with acousto optics due to my sonoluminescence project which began my contact with the LTC.
When I talked about my interest in TAG lenses, Dr. Noe asked me if I could make a TAG lens. Although I had seen diagrams showing each part of the device, instructions on construction was limited due to the fact that these lenses may be manufactured by the company in the future.
Dr. Noe recommended that I find a journal article where I can find a basic device design that will allow me to create my own device in order to gain a better understanding of the physics involved.
Looking up acoustics on the American Journal of Physics with Dr. Noe provided me with several articles. The first article was an experiment meant for the undergrad level that provides an experimental outlook on how to measure sound speed through diffraction.
However, when I decided to read the article more in depth, the device created ironically follows the same basic principles as a TAG lens.
In the described device, a piezo electric transducer as shown above sends ultrasound frequencies which changes the pressure of the liquid, hence changing the refractive index, exactly like a TAG lens. The methodology seems to be the same as a TAG lens, simply under another title and used for other means. This project used the methodology to create acoustic grating in order to measure sound speed.
Changing the density of the water will provide different indices. For a research idea, find how much one factor needs to be altered in order to change the index of refraction by a certain degree. For example, changing the frequency by _____ amount will change the index by _____. Try to find a trend. This would allow individual indices to be obtained allowing properties of these indices, such as refraction, to be tested. Indices for particular materials can be tested without obtaining the materials themselves.
Article with device construction written by Diego A. Luna and associates. Published in 2002: http://www.calpoly.edu/~jfernsle/Classes/PHYS452/Formal%20writeup%20guide/SampleAJP.pdf
July 11, 2014
Yesterday in conversation, Dr. Noe mentioned the interest of past LTC fellow Marissa in TAG lenses, or tunable acoustic gradient index lenses. I decided to do research on these lenses due to the fact that he mentioned that they adjust refractive indices.
TAG lenses are comprised of a fluid fild cavity with a piezoelectric transducer. The piezoelectric transducers is used to send acoustic standing sound waves that adjust the density of the fluid. Adjusting the fluid's density adjusts the fluid's refractive index.
When the piezoelectric transducers are driven by a kHZ frequency, the laser beam can be transformed from a Gaussian beam into a multiscale Bessel beam on its edges and a conventional Bessel beam in the center.
Bessel beams can be concentrated without the possibility of diffraction. This characteristic of Bessel beams allow them to be favorable for optical trapping. An advantage in using Bessel beams for optical trapping is the fact that Bessel beams can trap particles that have a range of multiple indices. Additionally, Bessel beams can be used to trap multiple particles around its ring structure due to the fact that there are no specific focuses.
A video showing the use of TAG Lens in Optical Tweezers is shown below:
Article about using Bessel beams in Optical Tweezers: http://arxiv.org/ftp/arxiv/papers/1007/1007.5027.pdf
Basic TAG lens infromation: https://sites.google.com/site/euanmcleod/research/tag-lenses
July 10, 2014Recent research done with supercooling includes investigation into the structure of supercooled water using X-ray pulses and the possibility of supercooled organs.
In the June 2014 issue of Nature, scientists sent X-ray pulses through supercooled water droplets and become scattered by the electrons of the droplets. Diffraction rings picked up by a detector show the ring's pattern and its Bragg peaks. Bragg peaks occur from particle waves and electromagnetic radiation that combine to form constructive interference, causing a unique type of scattering. As temperatures of the supercooled water continued to decrease, density and liquid structure changed in a continuous manner.
Nature article: http://www.nature.com/nature/journal/v510/n7505/pdf/nature13266.pdf
In the July 2014 issue of nature medicine, scientists submerged rat livers into temperatures below the freezing point. However, these scientists used anti-freezing materials to prevent crystallization. Combined with machine perfusion, these livers were sucessfully transfered after remaining in a supercooled state for 4 days.
Nature Medicine article: http://www.nature.com/nm/journal/v20/n7/pdf/nm.3588.pdf
July 9, 2014
Since supercooling is often induced by small changes to its environment, I decided investigate if lasers had ever been used to induce ice formation within super cooled liquids. The first article I encountered dealt with supercooled ice induced within acids. The second article I read proved that lasers can induce nucleation within water. However, I soon realized (to my suprise) that there are connections between this specific type of nucleation and sonoluminescence.
Optical breakdowns use lasers to trap and cavitate a bubble. The increased pressure resulting from the collapse creates an embryo crystal out of the bubble. The rest of the liquid crystallizes around the embryo.
Lindinger and associates created an experiment proving this process in 2007. Their device is shown below:
Lindinger's article: http://www.physik3.gwdg.de/~robert/paper_pdf/LMCL07.pdf
July 8, 2014
An article written by Murray and associates in May of 2010 investigated supercooling rates belonging to different droplet sizes induced by homogeneous nucleation.
Murray's article: http://www.researchgate.net/publication/44799704_Kinetics_of_the_homogeneous_freezing_of_water
Murray's design for his apparatus is shown below. A light source illuminated droplets chilled by a temperature contoller placed underneath the stage. Thermocouples were used to monitor temperature alterations. An optical microscope and digital camera was used to take video footage of the droplets as they hit the point of homogeneous nucleation.
Using the exponential growth formula, one can calculate nucleation rate, the number of nucleated droplets, etc. when all the other variables are obtained. The traditional exponential growth formula follows:
The formula can be altered with the specifics of the situation.
N1 = final number of remaining liquid droplets
No = initial number of liquid droplets
k = -JhomV. The system is a decay system as a result of the decreasing number of liquid droplets, causing the need for a negative rate. J hom represents the nucleation rate expressed as nucleation rate per volume per time.
To obtain the ratio of homogeneous nucleation to initial droplets, a person can subtract the ratio of liquid droplets remaining initial droplets (found with collected data) from 1 since the two ratios together account for all scenarios.
This logic can also be applied to the exponential formula. In order to find the number of nucleated particles, one must simply subtract the result acheived when applying the negative nucleation rate due to the fact that these numbers will account for all scenarios.
July 7, 2014
We started the day discussing the existence of the golden ratio and deriving phi using the ratios that determine its value. The ratio of the larger segment to the smaller statement is equal to the ratio of the combined segment over the smaller part. When these are labeled using variables such as a and b, the quadratic formula can be used to find the value of phi when the negative value is rejected.
We were then sent off to do research over possible topics of interest. I started off my research reading about the work of Hilary Fleischer, a former Simons fellow at the LTC. Hilary had been mentioned to me by my science research teacher, Mr. Kurtz, who had her as a past student. In her project, Hilary used soap films to observe the von Karman vortex. Hilary's idea from her research formed when reading a Scientific American article. I decided that I would look into current articles issued by that particular publication.
Hilary's LTC page: http://laser.physics.sunysb.edu/~hilary/
The Physics section of Scientific American website had an article discussing work by Anders Nilsson and associates. These scientists recently investigated the possibility of another water state besides the known solid, liquid, and gas. Nilsson's research delves into the idea of a critical point where water shows two phases as once, hence showing the properties of each phase. Supercooled water could be one such state. Supercooled is a term labeled to water when it functions as a liquid below the freezing point of 0 degrees Celsius.
Scientific American article about research: http://www.scientificamerican.com/article/liquid-water-in-an-icy-no-mans-land/
Nilsson's publication: http://www.nature.com/nature/journal/v510/n7505/pdf/nature13266.pdf
I next decided to investigate supercooled water itself. Supercooling can occur naturally. When conditions surrounding the supercooled state are changed, the liquid immediately transitions into a solid. This is occurs in clouds when supercooled water droplets are hit by airplanes, automatically transitioning into ice. A display of the supercooling process is shown below:
As seen in the display, supercooling can be accomplished using conventional materials. At home, a person can take a bottle containing distilled water and leave it in the freezer for 2-3 hours. When removing the bottle from the fridge, he or she has to be very careful or the water will supercool before the effect is desired. To achieve supercooling, the person needs to simply disturb the surrounding enviornment of the water through shaking or other means and the process will begin.
Water freezes instead of supercooling when there are imperfections in the system. Imperfections provide nuclei around which ice crystals can form. Without nuclei, supercooling takes place. However, there is a certain temperature at which the water will create its own nuclei causing the system to freeze. This is known as crystal homogeneous nucleation.
Supercooling has been blamed as the cause of plane malfunctions due to the accumulation of ice resulting from supercooled water droplets within clouds. However, a Boeing 777 crashed at Heathrow airport with failure in both of its engines due to supercooling in a different place. Investigators created mock-ups of the occurance and discovered that under such conditions, supercooling could have taken place with water molecules located in the plane's fuel tanks. Under a small system change, the water molecules would have frozen, causing the engine to fail.
July 3, 2014
The majority of the time I spent at the lab today consisted of learning html. Libby has been a great help in terms of teaching me the basics or aiding me when I do not understand how to use a specific command.
Libby showed me a guide set up by a LTC student named Rachel Sampson who worked at the LTC during the 2013-2014 year. Her guide has been a great help with understanding how to do the simple things such as opening files etc.
Rachel's LTC page: http://laser.physics.sunysb.edu/~rachels/
Rachel's Linux Guide: http://laser.physics.sunysb.edu/~rachels/Summer2013/linux
July 2, 2014
We began the day practicing our presentations with Melia in preparation for today's lunch talk. For the lunch talk, I have to present slower because my speed caused my practice presentation to be too short.
I also had a conversation with Dr. Noe where he suggested that I talk about the multi-frequency response of the bubble to sonoluminescence as a possible idea for the future in my presentation. This can be observed in the oscilloscope as shown by a picture captured by one of Dr. Noe's earlier students, Kenneth Lee, a Simons Fellow from 2002, below. During the sonoluminescence process, the bubble emits a fundamental frequency and a harmonic of the fundamental frequency which can be audibly heard as a buzzing noise. Since the two frequencies are of the same basic shape but one is slightly altered from the other, it can be assumed that the harmonic frequency is much higher than the fundamental frequency. For a project, I could investigate which specific harmonic is emitted and try to find the reasons behind this enigma.
Ken's LTC page: http://laser.physics.sunysb.edu/~ken/ http://laser.physics.sunysb.edu/~kevin/
I enjoyed listening to all the presentations during lunch. Although I really knew no prior information about any of the topics besides some of the basics, I was able to follow the discussions well and found them all to be interesting and informative.
After lunch, I found an interesting article surrounding a new technique developed to separate nuclear isotopes. Currently, calutrons remaining from World War II are used to bring ions to higher energy levels by spinning creating acceleration, causing the deflection of ions based on mass. However, this is a problem due to the age of calutrons and the large levels of energy used for operation, inducing the high cost of medical isotopes. Scientists Raizen and Klappauf from the University of Texas have created a new technique called MAGIS or the magnetically activated and guided isotope separation. The process uses a laser to excite vaporized isotopes, and then deflects the isotopes using magnetic fields. Each isotope becomes excited by a different laser of a certain wavelength, allowing certain isotopes to separate from others. Although I understand that this is unrealistic for a student project, I found the application of lasers to this area to be fascinating.
July 1, 2014
Today focused on making our abstracts and presentations suitable for the lunch talk tomorrow. Through the guidance of Melia and Dr. Noe, both my abstract and presentation were cut down and modified in order to make them more concise. My talk has become titled "Single Bubble Sonoluminescence: The Star in a Jar" after a discussion we had with Dr. Noe about the importance of titles to be both creative and informative.
My abstract for tomorrow's talk follows:
This past school year I have been investigating Single Bubble Sonoluminescence (SBSL) under the guidance of my dedicated science research teacher at Commack High School, Mr. Kurtz. Sonoluminescence is the process in which intense high frequency sound waves are used to induce cavitation in tiny bubbles trapped in a degassed liquid medium. Under just the right conditions, the temperature of the gas inside the cavitating bubble exceeds 10,000 K and the bubble to become a tiny point of light. The standard setup for SBSL is a 100 mL spherical flask with piezo-electric transducers (PZTs) attached on opposite sides. Another smaller PZT on the bottom of the flask acts as a microphone to monitor the response of the flask and the sound of the collapsing trapped bubble, which contains many high harmonics of the driving frequency. In my setup the fundamental resonant mode of the flask (largest microphone signal) was found at 24.5 kHz. Unfortunately as yet I have not been able to achieve SL or even trap a single bubble with my setup. In retrospect this was because the home audio amplifier I used could not provide enough voltage to the PZT, which was then unable to create a sufficiently intense sound pressure wave.
June 30, 2014
The first day began with a very nice welcome breakfast that allowed us to introduce ourselves. After breakfast, we were brought to the laser lab. Dr. Noe explained to us how the lab works and presented us with an optical toy known as a "mirage." This optical device consists of two curved mirrors facing each other in order to create a real image as the light beams converge at one point. We discovered that the mirrors are parabolic due to the symmetry of the light rays horizontally. This causes the rays to be parallel vertically, which indicates that the mirrors are parabolic in shape.
After a group lunch, we continued to discuss different optical phenomena. My favorite activity was when we applied focal lengths to the usage of magnifying glasses to burn paper. I joined two of the glasses together in order to observe what effect this would have on the burning spot. Although the magnifying glasses seemed to work more quickly as a team, the light spot used to burn the paper got smaller, indicating that the points are circles. Dr. Noe explained that this was due to the fact that the circles are images of the sun. One of his past students determined this on a day when he saw a cloud shadow passing through the circle. The afternoon continued with the application of focal lengths from the activity to light intensity of the spot and several more calculations.