Friday, August 21, 2015

URSP Student Rahib Zaman Develops A Novel Optical Transducer for Ultrasound Imaging based on the Photoacoustic Effect

Over the course of this summer, I have been fortunate enough to work in the Photoacoustics laboratory under the mentorship of Dr. Parag Chitnis. I am currently researching and developing a novel all-optical ultrasound transducer. The purpose of this project is to create a transducer that does not rely on the standard piezoelectric crystals, but rather employs the photoacoustic effect to image the body. The photoacoustic effect is the generation of sound waves from the absorption of light and subsequent thermal expansion of a material. This type of design will allow faster non-invasive scanning while producing high resolution 3D images deep within the body. I believe this project has the potential to revolutionize the medical imaging world and that is something I am very excited to contribute to.
When I chose my major as bioengineering, I had hopes of making medical imaging my profession. With that in mind, I began looking for ways to learn about the various imaging modalities outside of the classroom. My search led me to Dr. Chitnis who introduced me to this idea of creating an all new type of transducer for ultrasound imaging. I was fascinated by the idea from the beginning and I knew this would be the perfect opportunity to learn more about medical imaging as well as acquire some excellent research experience in the field. One thing led to another and now I am a funded OSCAR Researcher working with both undergraduate and graduate researchers at the Krasnow Institute.

On a weekly basis I spend my time reading published papers on optical transducers and performing experiments on the designs I have formulated. My design has two major parts: acoustic wave generation and acoustic wave detection. I am currently working on the generation portion. The lab where I work at has a very powerful high frequency pulsed laser system that I use to test the ability of certain materials to generate strong high frequency pressure waves. These experiments are tedious and, at times, frustrating but if there is one thing I have learned from this project is that research is rarely a straight path towards success. Even if my design does not work by the end of the research period, I would have left the lab with much more knowledge than I had when I first entered. That is a lesson that is constantly reinforced every week.  

Thursday, August 20, 2015

URSP Student Iris Stone Studies the Optical Properties of Charge Transfer (CT) Crystals

Participating in the summer URSP program through OSCAR has allowed me to continue my research with Dr. Vora, a physics professor whose research focuses on solid state physics. In my last blog post, I detailed the arduous but rewarding process of building a lab from scratch. After several months of hard work we’ve finally reached the point where we’ve been able to take real data! Our team and the types of materials we’re studying have also expanded, giving me a great opportunity to learn new science and make friends with like-minded students. 
Although I wasn’t originally sure what area of physics most interested me, my work with Dr. Vora over the past several months encouraged me to continue exploring solid state materials for my summer project. My primary goal this summer was to study the optical properties of charge transfer (CT) crystals. Unlike atomic crystals, in this case the crystal structure is formed by stacks of repeating donor and acceptor molecules. This unique arrangement gives way to emergent physics that goes beyond the individual properties of the constituent molecules. In the long run, our goal is to understand and harness these materials to achieve designer organic electronics. Organic electronics offer several advantages over traditional semiconductor technology, from lower cost of processing to compatibility with current production methods. They also offer the advantage of being lighter and thinner than traditional electronics and have great potential in flexible digital displays.

Unsurprisingly for scientists, my summer has been a lot about taking data and interpreting the results. For example, when we measure the absorption properties of CT Crystals in different stoichiometries (different ratios of acceptors and donor molecules) we see significant differences, suggesting that some ratios are conducive to co-crystallization (the stack-like arrangement) while others are not.

But the life of a lab research assistant isn’t all fun and graphs. In fact, on a daily basis I spend a lot of my time designing and optimizing our optical setups. Working with optics requires incredible precision, and even the slightest mistake in the alignment could disrupt our ability to take measurements. The really exciting moments come well after the design stage, when every aspect of the setup – the mirrors, lenses, beam splitters, rejection filters, and so on – are aligned perfectly. Only then can I fire up our spectrometer and watch the data roll in.  

The lab still sports a long to-do list, and frankly that’s the way I prefer it. I already have plans to continue my work with Dr. Vora into the fall semester, and hopefully beyond! The opportunity to work on these long-term projects and carry an idea through from start to finish has been an invaluable one. Every day I learn something new about the experimental process and the far-reaching applications of our research, offering me a glimpse into my future as a physicist.    

Wednesday, August 19, 2015

URSP Student Tiffany A Wynn Conducts Foraminifera Photogrammetry by Enhancing 3D Modeling Methods From SEM Images

Going into my final year at George Mason University, thoughts of how I would apply my new knowledge to the working world quickly started to flood my mind. As a biology major with a passion for paleontology, I decided to dedicate my future to observing long and short term trends of the past to better understand our future. Some call this evolutionary biology and others call it conservation paleobiology. Regardless of its name, I quickly realized I needed to narrow my focus. To do so, I enrolled in a Paleontological Training Program (PTP) at the Smithsonian’s National Museum of Natural History (NMNH). During the course we had many speakers, one of which was Dr. Brian Huber (the chairman of the Department of Paleobiology). He gave a convincing argument as to why working with forams in the Department of Paleobiology would be the best place to spend my summer.

What are forams you may ask? Forams, formally known as foraminifera, are single celled organisms that spend their time floating in the ocean (planktics) or dwelling on the ocean floor (benthics). Most create their shell (tests) out of calcium carbonate and some are heavily ornamented with agglutinated materials. They also use spindly pseudopodia to wrangle their dinner, which can be as large as a small shrimp! Yum. These fascinating microfossils offer valuable insight into our past and can provide much needed information on current marine ecosystems.

At the end of the PTP course, I decided I wanted to work with these valuable creatures. Luckily for me, my current mentor, Miss Loren Petruny had been working with forams for her Master’s thesis and needed a helping hand. It was through working with her and Dr. Huber, that I developed a keen interest with forams. Fast forward to the current summer. With her approval, I decided to expand upon Miss Petruny’s research in hopes to help streamline the process.  I am intrigued by her research taking these tiny microfossils and rendering 3D printed models.

My journey this summer has been a broadening experience to say the least. As a volunteer at the National Zoo and camera trapper for the Smithsonian Conservation Biology Institute, it is safe to say I am not unfamiliar with the inner goings of the Smithsonian. However, my internship through URSP has afforded me experiences I wouldn’t have otherwise been privy to. Let’s look at some of what I’ve been working on!

As previously performed by my mentor, I had large shoes to fill and needed to learn many skills before I could consider broadening her research. In doing so I needed all the help I could get from various staff at the NMNH. This involved type specimen selection with the help of the Department of Paleobiology’s Jennifer Jett. I would also need help with imaging these fine fossils, enter the Scanning Electron Microscopy lab manager, Mr. Scott Whittaker. Together, Jennifer and I selected a total of fifteen forams, all with different shell types. I won’t go into detail of what is what, but we wanted to have enough variety in the event a particular type was not easily imaged in the scanning electron microscope.
So how does one image a microfossil the size of a pinhead in a scanning electron microscope? I’m glad you asked. First needles made of tungsten wire are carefully crafted using a dipping technique in sodium hydroxide. To expedite the process, an electrical charge is sent through the fluid. Using the meniscus of the fluid and repeated depressions in the center, the wire is transformed from having a blunt end to a fine needlepoint.

The needle is then used to drill a hole in the center of a carbon stub. I created a total of five needles and successfully made six stubs (these can be reused as needed).  Then using a straight cactus needle, some dental wax, Elmer’s glue and a lot of steady fingers, the end result is a mounted foram ready for imaging. Now that my hands are dirty it is time to take some images! As seen here each foram is imaged one at a time.

Using a series of images taken from a scanning electron microscope (SEM) at varying degrees, images are rendered in a photogrammetry program such as AgiSoft. Once complete, the type specimen will be 3D printed.

As expected, research comes with many expectations; some are met and some are altered. Currently this week, I am working to better understand AgiSoft so that I may align images taken at different depths from two different SEM sessions. Once this is mastered, the final step is 3D printing our microfossils. This will complete my summer research and will provide a truly tangible experience.

Tuesday, August 18, 2015

URSP Student Ashley Frongello Researches the Domestication Hypothesis

Last winter in my psychology honors class, my now-mentor, Dr. Doris Davis, gave a presentation on a study in which a Border collie was trained to identify 1,022 different toys by name; fortunately for me, Dr. Davis was looking for a student to replicate this study with her two newly obtained Great Pyrenees puppies, and I jumped at the chance to work on a project so fetching.  For those unfamiliar with this breed, Great Pyrenees are huge, fuzzy, polar bear-esque canines, with stubborn temperaments likely stemming from historical autonomy.   In other words, as opposed to Border collies and other so-called “herding” dogs that are known for their apt communication abilities with humans (e.g., a farmer’s dog who can herd sheep back to the barn on the farmer’s command), Great Pyrenees still remain a breed who typically operate as guard dogs for the farm animals, independently of their owners.

My research is concentrating on what is referred to as the Domestication Hypothesis, which loosely states that the ability of dogs, like the aforementioned Border collie, to exhibit some features of human language, is the product of social communicative exposure with humans.  Bluntly speaking, however, this summer I have had the wonderfully fun task of spoiling my mentor’s two puppies, Marina and Sugar, rotten.  I regularly bring them new toys and train them to identify such with specific proper nouns through repetitive exercises and play, in turn I reward them with treats and tons of affection.  Some of Marina and Sugar’s favorite toys include Spaceship, a little, red, squeaky rocket ship and Trunks, a plush, squeaky elephant.

I have learned that there’s a definite quota of difficulty involved in animal behavioral research, but I love a challenge and I’m really thankful for the opportunity to independently problem-solve through them. I particularly have had a ruff time navigating the puppies’ natural insubordination and aversion to hot weather.  One example I can think of is how when I first tried to begin their experimental training, I realized that Marina and Sugar didn't know how to fetch!  My study revolves around the dogs using retrieval as a method of identification, and even though I had spent the months prior teaching them simple behavioral commands like sit and roll over, it never even dawned on me that they didn’t know how to play with toys!  They wouldn’t even touch the toys I showed them, never mind fetch them; but after a good week of training focused solely on touching, going to, and later fetching objects, I could finally restart the study.

As we are now reaching the tail end of the summer, my research is far from done!  I will continue to work with Marina and Sugar throughout the fall, and use this project for my honors thesis culminating next spring.  But I already have ideas for future experimentation with the pups to expand on this particular subject area of human-dog social cognition in Great Pyrenees.  Paws down, my experience with URSP has been a blast!

Monday, August 17, 2015

URSP Student Robert Argus Explores Numerical Methods of Solution

Most technologically useful materials arise as polycrystalline microstructures, composed of a myriad of small crystallites, grains, separated by interfaces, grain boundaries.  The energetics and connectivity of the network of boundaries are implicated in many properties across all scales of use, for example, functional properties, like conductivity in microprocessor wires, and lifetime properties, like fracture toughness in structures.  Engineering a microstructure to achieve a desired set of performance characteristics is a major focus in materials science.  In [1], a framework for modeling critical events in microstructure evolution was proposed and applied to a simplified one-dimensional system.  By regarding a system of grain boundaries as a collection of interacting particles, one can then utilize the machinery of statistical mechanics, in particular, Boltzmann kinetics.  The results obtained were found to compare favorably with numerical simulations as well as experimental data in both the distributions of grain boundary lengths and orientations.

In my research, I have utilized an analogous approach to extend prior work to a more realistic two-dimensional model.  The extension to two dimensions is non-trivial in that topological reconfigurations (critical events) such as neighbor switching, absent in one dimension, must now be treated.  The resulting model is a partial integro-differential equation describing the evolution of the distribution of misorientations in a two-dimensional grain boundary network, a distribution which is of great importance to materials scientists and engineers.  Currently, I am exploring numerical methods of solution including the method of finite differences and Direct Simulation Monte Carlo.  The plausibility of the derived model will require numerical validation by means of comparison with results gathered from numerical simulations and experimental data.  Next summer I am applying for an NSF funded REU out of Harvard’s Materials Science and Engineering Center and I believe that having participated in the EXTREEMS-QED program and having done research in the field of materials science will greatly increase my chances of being selected.  The work I am doing is also topical in that in 2011, under the Obama administration, the Materials Genome Initiative was launched, a multi-agency initiative designed to create a new era of policy, resources, and infrastructure that support U.S. institutions in the effort to discover, manufacture, and deploy advanced materials twice as fast, at a fraction of the cost. 


[1] Barmak, K., et al. "A new perspective on texture evolution." International Journal on Numerical Analysis and Modeling 5 (2008): 93-108.

Friday, August 14, 2015

URSP Student Nicole Nmair Evaluates the Suitability of the Micro-Deval Test to Estimate Durability of Base Aggregates of Northern Virginia

I remember sitting in soil mechanics class (CEIE 331) where my professor, now OSCAR mentor, Dr. Burak Tanyu passionately spoke about the comprehensive process of road construction. I walked away from that class with more questions than answers.  Some questions included the type of aggregate used and its durability. Majority of research on road aggregate is conducted through the use of the Micro-Deval and the process indicated by ASTM D6928. Therefore my research was to investigate the credibility of the correlation between the results from the Micro-Deval test and that of field performance. In addition I sought to understand the correlation between aggregate and revolution, aggregate and abrasion, and lastly, aggregate and saturation time. This project has opened my eyes to a potential future in the geotechnical field. I was revealed to the necessity in understanding the lab component of engineering. As an aspiring master’s degree student, being exposed to research and being able to differentiate between the lab performance and that in the field is vital. This project has solidified my desire and success in the engineering world.

My week consists of a balance between laboratory work and literary research. With regards to the experimentation, this includes weighing samples, abrasion, washing samples, oven-drying samples, and running the Micro-Deval which in itself takes about four hours. It also includes preforming other tests such as specific gravity and absorption tests as well as sieve analyses. I also meet up with my professor on a weekly basis to discuss the results of the experiment and the literature. The literature I continuously read includes ASTMs, scientific articles, past experiments, and technical reports.

Every week, new discoveries are made as I perform more experiments. This week I discovered the lack of correlation between saturation time and the percent loss of aggregate due to abrasion. This is significant for it allows us to conclude that a saturation time of one hour is a good indicator of aggregate loss with regards to diabase, limestone, and slate. Overall, this experience has shown me who I am as a geotechnical researcher.