This is a past event.

Please join physics graduate students, Krishna Teja Vedula and Raksha for their presentations on Thursday, January 15 at 4 PM - Fisher Hall 139.

Krishna Teja Vedula (Advisor: Tiffany Lewis)

MODELING SYNCHROTRON POLARIZATION IN BLAZARS : APPLICATION TO 3C 454.3

Blazars, the most energetic sustained objects in the universe, are jetted active galaxies with one jet pointed toward Earth. Magnetic fields are central to particle acceleration and radiation processes in blazar jets, though they cannot be directly observed. The degree of order in the magnetic field offers a critical diagnostic of jet composition and acceleration mechanisms. We compare optical polarization measurements and simulations broadband multiwavelength spectra from one blazar, with a new self-consistent theoretical model, to constrain the physical parameters and gain a better understanding of conditions within the blazar zone. We derived and implemented the synchrotron polarization model in the context of an existing particle transport model. This is a novel approach to calculating blazar polarization because it facilitates taking particle acceleration processes into account directly. We compare this theoretical model to multiwavelength observations of the blazar, 3C 454.3 from two periods representing a significant flare and a quiescent period to demonstrate the flexibility of the physics we implemented. For each spectral period, we co-analyze the polarization degree available with the optical data.

Raksha (Advisor: Yoke Khin Yap and Dongyan Zhang)

SYNTHESIS AND CHARACTERIZATION OF BORON NITRIDE DOTS FOR HIGH-BRIGHTNESS FLUORESCENT PROBES

Intracellular gene detection demands fluorescent probes that offer high brightness, photostability, and biocompatibility at low target concentrations. Conventional organic dyes suffer from low fluorescence, while semiconductor quantum dots introduce toxicity. Here, we present high-brightness probes (HBPs) that overcome all these shortcomings. We synthesize HBPs by using boron nitride dots (BN dots) as the zero-dimensional nanocarriers. BN dots are sub-5 nm hexagonal boron nitride nanocrystals with a wide bandgap (~6 eV) and electrically insulating, resulting in minimal fluorescent quenching and without intrinsic visible fluorescence. These properties enable the conjugation of a series of organic dye molecules on each BN dots without quenching or
photoinduced electron transfer, preserving high quantum yield and high signal-to-noise ratios. When functionalized with sequence-specific oligonucleotides, HBPs enable detection of intracellular gene sequences with strong fluorescence >10X than regular organic dyes. The translational relevance of this platform was further validated through an NSF I-Corps study involving 100 customer interviews, which identified brightness, stability, and biocompatibility as critical unmet needs that BN-dot HBPs directly address.