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APS practice talks

APS practice talks

Wednesday, March 10, 2021 at 4:00 pm
Graduate students: Okan Agirseven, Amit Bashyal, and Guangxi (Max) Feng, Guanyu Li

Okan Agirseven: "Crystallization of Titanium Dioxide Polymorphs from Radio Frequency-Sputtered, Amorphous Thin-film Precursors"

Titanium dioxide is a versatile wide bandgap transparent semiconducting oxide with three well known polymorphs: anatase, rutile, brookite. The crystalline polymorphs of TiO2 require high temperature annealing processes to form from an amorphous precursor. Their research aims to understand the formation behavior of these metastable crystalline polymorphs of TiO2 as related to amorphous precursor properties. They began their study by annealing films deposited by pulsed laser deposition and extended this study further with TiO2 precursors deposited by RF-sputtering. These deposition methods coupled with particular oxygen partial pressure ranges and film thicknesses defined a region of phase space where particular polymorphs formed. They investigate structural, optical and electrical properties of these films with a wide range of analysis methods including Raman spectrometry, XRD, SEM, EPMA, optical spectrometry and Hall-effect analysis.

Amit Bashyal: "Charged Current Quasi-Elastic (CCQE) Like Cross-section Measurement with Anti-neutrinos in Hydro-carbon Target"

Neutrinos are electrically neutral elementary particles with an extremely small interaction cross-section. Since they are electrically neutral, have extremely small mass and rarely interact with matter, they can help us to probe the structure of the nucleus, convey the information of the far edges of the universe and also understand the origin of matter in the universe. Neutrino interaction cross-section measurements help us to understand the nuclear structure, its underlying physics, and provide valuable data to the current and the future neutrino experiments which aim to answer big questions regarding our universe. In this talk, they will give a brief overview of the neutrinos, how they can answer some of the big open questions in physics and finally the measurement of CCQE Like cross-section with anti-neutrinos.

Guangxi (Max) Feng: "Kinesin-14 Motors with Novel Motility Behaviors and Functions"

Kinesin-14s are microtubule-based motor proteins that play important roles in mitotic spindle assembly. Ncd-type kinesin-14s are a subset of kinesin-14 motors that exist as homodimers with an N-terminal microtubule-binding tail, a coiled-coil central stalk, a neck, and two identical C-terminal motor domains. To date, no Ncd-type kinesin-14 has been found to naturally exhibit long-distance minus-end-directed processive motility on single microtubules as individual homodimers. Here, they show that GiKIN14a from Giardia intestinalis is an unconventional Ncd-type kinesin-14 that uses its N-terminal microtubule-binding tail to achieve minus-end-directed processivity on single microtubules over ┬Ám distances as a homodimer. Theirr results reveal that the N-terminal tail of GiKIN14a is a de facto dual regulator of motility and reinforce the notion of the central stalk as a key mechanical determinant of kinesin-14 motility.

Guanyu Li: "Causal analysis of synchronized neural networks on chip"

Neural cells are the very fundamental units of the brain and nervous system, they are responsible for sensing the external environment and send out commands to muscle or other parts of the body. Neural cells will be wiring with each other to form neural networks to sense the external environment and make responses. In our project, we investigate ATP stimulated calcium dynamic for monolayer of KTaR-1 cells, we analyse calcium intensity data by statistical method and construct the network based on that, then we analyse the network structure under different stimulation condition in order to understand how temporal stimulation would shape the structure of neural network.

Xavier Siemens