Production and characterization of MutS for use in error correction

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 20-21).The availability of inexpensive synthetic DNA (oligonucleotides) has allowed for the synthesis of longer, gene-length constructs of DNA. However, a critical barrier to making this technology a low-cost and high-throughput process has been due to the rate at which errors pervade the final product. The current state of the error reduction technology includes three different categories: error filtration, error correction, and error prevention. My research is a joint project as well as an addendum to the work done by Research Scientist Dr. Peter Carr and current MIT Department of Biological Engineering Masters Student Jason Park (MIT '05) who have been working on research in gene synthesis error correction over the past several years. I have been working very closely with both Dr. Carr and Jason Park on this research for the past two years. We have a publication we're about to submit in regards to optimizations of gene synthesis and a significant portion of my thesis deals with work done for the upcoming publication. My work includes optimizing the synthesis of large gene constructs, the synthesis of new hyper-thermophilic MutS proteins, characterizing these proteins using instruments such as the circular dichroism spectrophotometer and the Evotec MF20, as well as perfecting old error correction protocols while designing several new ones.by Samuel James Hwang.S.B

Continuous-wave and Transient Characteristics of Phosphorene Microwave Transistors

Few-layer phosphorene MOSFETs with 0.3-um-long gate and 15-nm-thick Al2O3 gate insulator was found to exhibit a forward-current cutoff frequency of 2 GHz and a maximum oscillation frequency of 8 GHz after de-embedding for the parasitic capacitance associated mainly with the relatively large probe pads. The gate lag and drain lag of the transistor was found to be on the order of 1 us or less, which is consistent with the lack of hysteresis, carrier freeze-out or persistent photoconductivity in DC characteristics. These results confirm that the phosphorene MOSFET can be a viable microwave transistor for both small-signal and large-signal applications.Comment: Accepted for oral presentation at IMS 201

Modeling Power Losses in Electric Vehicle BLDC Motor

In order to design an efficient motor cooling system, it is important to accurately predict the power losses which are normally dissipated in form of heat. This study presents an analytical method for estimating bearing frictional losses and numerical method for estimating electromagnetic losses for an electric vehicle BLDC motor. The power losses obtained are used as heat sources when evaluating the thermal performance of the motor. The results showed that electromagnetic losses are dominant and contribute over 80% of all losses, while bearing losses contribute about 12% of the total electric motor. The results also showed that bearing losses increase significantly with increasing speed or load. Keywords: BLDC motor, bearing frictional losses, electromagnetic losses, joules losses, eddy current losse

Toward an artificial Mott insulator: Correlations in confined, high-density electron liquids in SrTiO3

We investigate correlation physics in high-density, two-dimensional electron liquids that reside in narrow SrTiO3 quantum wells. The quantum wells are remotely doped via an interfacial polar discontinuity and the three-dimensional (3D) carrier density is modulated by changing the width of the quantum well. It is shown that even at 3D densities well below one electron per site, short-range Coulomb interactions become apparent in transport, and an insulating state emerges at a critical density. We also discuss the role of disorder in the insulating state.Comment: Accepted for publication in Physical Review B (Rapid Communication