A newsletter spotlighting the research of IIT
student researchers at IIT make an important contribution to the
scientific world. To bring attention to some
of the outstanding graduate students within all IIT departments,
the Graduate College is publishing a monthly newsletter spotlighting
individual students and their research.
Cholesterol, a small fat lipid molecule produced abundantly by the liver, is one of the major components of all cell membranes. A cell membrane is no longer pictured as a passive barrier between the inner and outer worlds of the cell. Instead it is seen as a smart dynamic platform involved in a number of crucial biochemical cellular processes such as virus entry, cell-cell communication, etc. Structural, dynamical, and functional properties of the membrane are determined by the lipid composition. Cholesterol, in particular, has a tremendous impact on membrane characteristics because of its unique structure. Accumulating evidence indicates that normal cholesterol content in cell membranes is required for the development of one type of disease, for example AIDs/HIV, but is often altered in the course of another pathology such as Alzheimerís. Exactly how cholesterol modulates the properties of cell membrane remains an open issue.
Hoping to find an explanation for this, Andrey Ivankin, as part of his doctoral research and working with a group under the guidance of Dr. David Gidalevitz, has focused on studying cholesterol-lipid interactions. Because of the limitations of the contemporary tools used to study biological membranes and the complexity of the membranes - there are up to 1000 lipid species - research is performed using model lipid membranes. These model membranes have been mimicked with cholesterol-containing lipid monolayers formed at the air-liquid interface. In contrast to other model systems, this approach provides thorough control over lipid composition and area per molecule, which allows more closely reaching true biological conditions. X-ray radiation studies undertaken at the Advanced Photon Source at Argonne National Laboratory have been joining with the IIT lab using fluorescence microscopy imaging to gain insight into both macroscopic (order of mm) and sub-molecular (order of 0.1 nm) details of cholesterol-lipid interactions. Study results provide hard evidence in support of one of the existing theoretical models of cholesterol impact on membrane lipids and offer new details. Ivankinís work in this area was recently recognized with a Ludo Frevel Crystallography Scholarship.
Recent advances in wireless network communications have led to the development of a promising technology known as wireless mesh networks (WMN) that has the potential to provide wireless services in locations where there is currently little or no infrastructure.
In WMNs, a collection of wireless mesh routers (usually mounted on rooftops, street lights, stop lights etc) provides network access to the mobile clients such as laptops, PDAs, or cellular networks. The communications between these mesh routers are realized by radio transmissions, usually in a multi-hop fashion. One or more mesh routers in the network are connected to the Internet and serve as gateways to provide Internet connectivity for the entire mesh network. With the advent of mesh networks, the users can be online anytime, anywhere.
In spite of the recent advances, several challenges remain, among them interference in multi-hop wireless transmissions, cooperation and secure communication among mesh routers, and capacity improvement.
Devu Manikantan Shila, a doctoral student in the Electrical and Computer Engineering Department, is focusing her research on resolving issues related to interference by proposing novel link quality route metrics. These metrics helps us to find paths with less congestion, minimum packet loss, a low level of interference, and a high data rate.
Regarding issues with security, Shila has investigated various mechanisms to improve security in multi-hop wireless networks. She has proposed practical algorithmic and game theoretic solutions that have the potential to find highly secure paths, in addition to low levels of interference and high throughput. During her evaluation of the proposed solutions, Shila has discovered several challenges, such as new medium access layer and network layer enhancements to lessen interference and improve security, which she will endeavor to solve.
Additional information on Shila’s research may be found on her website http://www.ece.iit.edu/~dshila.
Kavin Ammigan, a Ph.D. candidate in the MMAE department has been working under Dr. Herek Clack at the Advanced Thermal and Environmental Systems Research Laboratory (ATESR), on research focused on micro-scale fuel droplet vaporization. The project is related to the development of millimeter-scale micro-electro-mechanical systems (MEMS). Power MEMS are millimeter-scale combustors which can deliver power densities (power per unit volume) of about 2000 mega-watts per cubic meter as compared to the 0.4 mega-watts per cubic meter power density obtained from lithium batteries. As a result, there is increased interest in developing power MEMS which may be used in applications previously powered by lithium batteries. Military interest derives from the need to deploy remote sensors and devices, whereas commercial interest centers on the replacement of batteries in a variety of portable electronics.
All combustion-driven power MEMS so far have only been developed with gaseous fuels. One of the main challenges facing the future of power MEMS is its development with liquid fuel. Liquid fuel provides many advantages over gaseous fuel in terms of higher energy densities and low storage volumes, hence providing longer refueling intervals. However, fuel combustion at the micro-scale faces many challenges, which are not present in conventional combustion devices such as a car engine. Complete combustion requires that the liquid fuel vaporizes and mixes thoroughly with air in a short period of time. For power MEMS, the miniaturization of the combustion chamber may lead to asymmetric gas flows and heat distribution in the chamber, which in turn results in uneven heating and vaporization of fuel droplets. This has a direct impact on the combustion of the fuel.
Therefore, Kavinís research is to look at how fuel droplets vaporize under such conditions. This is performed using a diagnostic technique called Planar Laser Induced Fluorescence (PLIF). PLIF is an optical diagnostic technique widely used for flow visualization and quantitative measurements. Over the last four years, he, along with other researchers has been involved in setting up this diagnostic tool at the lab to obtain concentration measurements of fuel droplet vaporization. The fuel droplets are exposed to the conditions prevalent in the millimeter-scale combustors and images from the PLIF technique reveal how the fuel vapor vaporizes. Such experimental data can then be incorporated into numerical models to predict combustion, used to improve the liquid fuel delivery method and eventually identify ways to improve combustion at the micro-scale.
Shaojie Tang is a third year Ph.D. student in computer science. His passion for computer science research originates from the strong belief that ubiquitous computing will significantly change our world and contribute to the progression of human society. Tang’s interest in the field of algorithm design for wireless networks has led him to his current area of research.
Currently he is studying the capacity of the wireless network, trying to determine the largest amount of information that can be transmitted through a given random wireless network. This is essential for network planning, as it provides an approximate idea of the capacity of a wireless network. Tang has been a co-author of several papers on this topic and has presented at leading conferences in Computer Science, such as ACM MobiCom, ACM MobiHoc, and IEEE INFOCOM.