Ahreum Hwang

Quantum Electronic Transport of Topological Surface States in β-Ag2Se Nanowire

Single-crystalline β-Ag2Se nanostructures, a new class of 3D topological insulators (TIs), were synthesized using the chemical vapor transport method. The topological surface states were verified by measuring electronic transport properties including the weak antilocalization effect, Aharonov-Bohm oscillations, and Shubnikov-de Haas oscillations. First-principles band calculations revealed that the band inversion in β-Ag2Se is caused by strong spin-orbit coupling and Ag-Se bonding hybridization. These investigations provide evidence of nontrivial surface state about β-Ag2Se TIs that have anisotropic Dirac cones.

Composition-selective fabrication of ordered intermetallic Au?Cu nanowires and their application to nano-size electrochemical glucose detection

Bimetallic nanostructures can provide distinct and improved physicochemical properties by the coupling effect of the two metal components, making them promising materials for a variety of applications. Herein, we report composition-selective fabrication of ordered intermetallic Au-Cu nanowires (NWs) by two-step chemical vapor transport method and their application to nano-electrocatalytic glucose detection. Ordered intermetallic Au3Cu and AuCu3 NWs are topotaxially fabricated by supplying Cu-containing chemicals to pre-synthesized single-crystalline Au NW arrays. The composition of fabricated Au-Cu NWs can be selected by changing the concentration of Cu-containing species. Interestingly, Au3Cu NW electrodes show unique electrocatalytic activity for glucose oxidation, allowing us to detect glucose without interference from ascorbic acid. Such interference-free detection of glucose is attributed to the synergistic effect, induced by incorporation of Cu in Au. We anticipate that Au3Cu NWs could show possibility as efficient nano-size electrochemical glucose sensors and the present fabrication method can be employed to fabricate valuable ordered intermetallic nanostructures.

Facile and sensitive detection of influenza viruses using SERS antibody probes

It is highly important to identify influenza viruses rapidly and accurately for the prevention of future pandemic outbreaks. We developed an easy and sensitive influenza virus detection method using surface-enhanced Raman scattering (SERS) antibody probes. The SERS antibody probes can be prepared easily by mixing Au nanoparticles, gold binding peptide-protein G, and antibodies without complicated chemical or biological reactions. They also retain the optimal conformation for the antibodys interaction with Influenza A/CA/07/2009 (pH1N1), allowing us to detect pH1N1 sensitively and selectively. This method provides a detection limit of 4.1 × 103 TCID per mL and is highly selective for pH1N1. We anticipate that this method can be useful in a wide range of immunoassays.

Macroscopic Quantum Tunneling in Superconducting Junctions of β-Ag2Se Topological Insulator Nanowire

We report on the fabrication and electrical transport properties of superconducting junctions made of β-Ag2Se topological insulator (TI) nanowires in contact with Al superconducting electrodes. The temperature dependence of the critical current indicates that the superconducting junction belongs to a short and diffusive junction regime. As a characteristic feature of the narrow junction, the critical current decreases monotonously with increasing magnetic field. The stochastic distribution of the switching current exhibits the macroscopic quantum tunneling behavior, which is robust up to T = 0.8 K. Our observations indicate that the TI nanowire-based Josephson junctions can be a promising building block for the development of nanohybrid superconducting quantum bits.

Naked eye detection of Salmonella Typhimurium using scanometric antibody probe

Background: In Africa, malaria has continued to be a big dilemma and a primary cause of mortality and morbidity especially among children under the age of 5, pregnant women and immunocompromised people for example people infected with HIV/AIDS. Despite global efforts in the management and eradication towards malaria, African countries have fallen behind due to many factors. However, the availability of preventative method such as longlasting insecticide treated bed nets (LLIN), insecticide treated nets (ITN), and indoor residual spraying (IRS) has been instrumental towards eradicating malaria in Africa. While other countries in the world have managed to eradicate malaria, doubts arise in Africa due to the effectiveness of present measures. Consequently, this study evaluates malaria eradication strategies in Africa, the main objective of this study is to detect if eradication strategies such as ITN and IRS methods are reducing the rate of malaria.So Yeon Yi1 , Seul-Gee Hwang1 4 , Jeong Moon1, Gayoung Eom2, Ahreum Hwang2, Jieun Sim1 3 4, Eun-Kyung Lim1 3, Jinyoung Jeong1 3 4, Bongsoo Kim2, Taejoon Kang1 3 4 ∗, and Juyeon Jung1 4 ∗ 1Hazards Monitoring Bionano Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea 2Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea 3BioNano Health Guard Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 34141, Korea 4Major of Nanobiotechnology and Bioinformatics, University of Science and Technology, Daejeon 34113, Korea