pH Paper Drawing with Chemistry

My project is connecting science with visual art via pH drawing and it has changed a lot from my original plan, but the purpose of this project has not been changed. The combination of art and science in this project can help people understand the messages of how their behaver effect the pH of an environment without the limitation of the science background. There are two part in my project. For the first project, I designed a pH paper drawing activity for children in the Linn County STEAM Fair by using the pH indicator paper to simulate a natural environment, such as ocean, soil or even human body, and drawing on it with baking soda solutions that provide a red color. Then, paintings were shown in the Iowa City Public Library. This painting displacement was open to the public, especially the local community within all ages. Paintings are visual art that can enlighten people universally without languages. My goal is to create a new way for people to connect with science by bonding science with art and bring excitement and interest for the general public

Edge Augmentation on Disconnected Graphs via Eigenvalue Elevation

The graph-theoretical task of determining most likely inter-community edges based on disconnected subgraphs' intra-community connectivity is proposed. An algorithm is developed for this edge augmentation task, based on elevating the zero eigenvalues of graph's spectrum. Upper bounds for eigenvalue elevation amplitude and for the corresponding augmented edge density are derived and are authenticated with simulation on random graphs. The algorithm works consistently across synthetic and real networks, yielding desirable performance at connecting graph components. Edge augmentation reverse-engineers graph partition under different community detection methods (Girvan-Newman method, greedy modularity maximization, label propagation, Louvain method, and fluid community), in most cases producing inter-community edges at >50% frequency.Comment: 6 pages, 3 figure

Josephson Junctions and SQUIDs Based on CVD Graphene

Josephson junctions and superconducting quantum interference devices (SQUIDs) with graphene as the weak link between the superconductors have been intensely studied in recent years, with respect to both fundamental physics and potential applications. Since the carrier density and resistivity of graphene are heavily dependent on the Fermi level, Josephson junctions and SQUIDs with graphene as the weak link can have their I-V properties easily tuned by the gate voltage. However, most of the previous work on superconductor-graphene-superconductor (SGS) Josephson junctions and SQUIDs was based on mechanically exfoliated graphene, which is not compatible with wafer-scale production. In this project, we have greatly improved the availability and applicability of graphene-based Josephson junctions and SQUIDs. We developed a method to fabricate Josephson junctions and SQUIDs with graphene grown by chemical vapour deposition (CVD) as the weak link. We demonstrate that very short, wide CVD-graphene-based Josephson junctions with Nb electrodes can work without any undesirable hysteresis in the electrical characteristics from 1.5 K down to a base temperature of 320 mK, and the critical current can be effectively tuned by the gate voltage by up to an order of magnitude. As a result, dc SQUIDs made up of these junctions can have their critical current tuned by both the magnetic field and the gate voltage. We also obtained evidence for ballistic transport in SGS junctions as short as 50 nm. We found that even for junction as wide as 80 µm, the critical current shows an ideal Fraunhofer-like interference pattern in a perpendicular magnetic field, indicating the distribution of supercurrent is uniform. We studied the definition of Josephson penetration depth, and proposed a new formula for 2D coplanar junctions

Simulating the Spread of Epidemics in China on the Multi-layer Transportation Network: Beyond the Coronavirus in Wuhan

Based on the SEIR model and the modeling of urban transportation networks, a general-purpose simulator for the spread of epidemics in Chinese cities is built. The Chinese public transportation system between over 340 prefectural-level cities is modeled as a multi-layer bi-partite network, with layers representing different means of transportation (airlines, railways, sail routes and buses), and nodes divided into two categories (central cities, peripheral cities). At each city, an open-system SEIR model tracks the local spread of the disease, with population in- and out-flow exchanging with the overlying transportation network. The model accounts for (1) different transmissivities of the epidemic on different transportation media, (2) the transit of inbound flow at cities, (3) cross-infection on public transportation vehicles due to path overlap, and the realistic considerations that (4) the infected population are not entering public transportation and (5) the recovered population are not subject to repeated infections. The model could be used to simulate the city-level spread in China (and potentially other countries) of an arbitrary epidemic, characterized by its basic reproduction number, incubation period, infection period and zoonotic force, originated from any Chinese prefectural-level city(s), during the period before effective government interventions are implemented. Flowmaps are input into the system to trigger inter-city dynamics, assuming different flow strength, determined from empirical observation, within/between the bi-partite divisions of nodes. The model is used to simulate the 2019 Coronavirus epidemic in Wuhan; it shows that the framework is robust and reliable, and simulated results match public city-level datasets to an extraordinary extent.Comment: 12 pages, 7 figure