Correlation Assisted Phonon Softenings and the Mott-Peierls Transition in VO2_{2}

To explore the driving mechanisms of the metal-insulator transition (MIT) and the structural transition in VO2, we have investigated phonon dispersions of rutile VO2 (R-VO2) in the DFT and the DFT+U (U : Coulomb correlation) band calculations. We have found that the phonon softening instabilities occur in both cases, but the softened phonon mode only in the DFT+U describes properly both the MIT and the structural transition from R-VO2 to monoclinic VO2 (M1-VO2). This feature demonstrates that the Coulomb correlation effect plays an essential role of assisting the Peierls transition in R-VO2. We have also found from the phonon dispersion of M1-VO2 that M1 structure becomes unstable under high pressure. We have predicted a new phase of VO2 at high pressure that has a monoclinic CaCl2-type structure with metallic nature

Magnetically-driven Therapeutic Agents Delivery System using Iron Oxide Nanocages and Enhancement of Exosome Secretion, a Potential Biological Drug Delivery Carrier

Nano-scale particles have attracted research attention due to their differences in properties such as penetration, circulation, and toxicity compared to bulk materials. This thesis mainly focused on using 20 nm iron oxide nanoparticles as siRNA delivery carriers under the alternating magnetic field and the development of a method to amplify the secretion of 150 nm exosomes from the cells, which could potentially use as a biological drug carrier. Chapter 2 discusses a magnetically driven nanoparticle therapeutic agent delivery system, which efficiently modified the gene expression post-transcriptionally. In this work, we examined whether the caged-shaped 20nm iron oxide nanoparticles (IO-nanocages) can escape from the endosomes when an alternating magnetic field (AMF) is applied and efficiently deliver siRNA to the cytoplasm before digested in lysosomes. Superconducting quantum interference device (SQUID) measurements revealed that 20nm IO-nanocages are dominated by Brownian relaxation as a response to the AMF at 335 kHz. It was observed that the endosomal membrane was ruptured when 335 kHz magnetic field was applied due to the Brownian movement of 20 nm IO-nanocages and released to cytoplasm. After AMF application, targeted gene expression reduced significantly, which revealed the improvement of the siRNA delivery. Chapter 3 explores the magnetic-driven delivery system further by delivering mGluR5 siRNA to the metastatic osteosarcoma cells. It has been studied that type 5 metabotropic glutamate receptor, mGluR5, is required to proliferate metastatic osteosarcoma cells. Therefore, the proliferation of the osteosarcoma cells would decrease when the activity of mGluR5 is silenced. The results elucidated that the mGluR5 siRNAs were successfully delivered by IO-nanocages under AMFs, and the reduction of mGluR5 expression led to cell death. The superparamagnetic properties of IO-nanocages could control the release of siRNA from the IO-nanocages by applying AMFs, resulting in the suppression of targeted gene expression. Chapter 4 describes the enhancement of exosome secretion from the cells by self-assembling synthetic peptide, NapFFK(NBD)Yp. The phosphate group on the peptide will be cleaved by alkaline phosphatase upon entering the cells and self-assemble to form a hydrogel near the endoplasmic reticulum (ER). It has been known that ER stress causes increasing in exosome generation, and we found out that the formation of hydrogel near ER increased cellular stress to amplify the exosome secretion by 4.5-6 folds in MDA-MB231 cells and Bone Marrow Dendritic Cells. This method could improve the application of exosomes as drug delivery carriers, which has limitations due to the low yield of exosome generation from the cells in current research

Functional screening of aldehyde decarbonylases for long-chain alkane production by Saccharomyces cerevisiae

Background: Low catalytic activities of pathway enzymes are often a limitation when using microbial based chemical production. Recent studies indicated that the enzyme activity of aldehyde decarbonylase (AD) is a critical bottleneck for alkane biosynthesis in Saccharomyces cerevisiae. We therefore performed functional screening to identify efficient ADs that can improve alkane production by S. cerevisiae

Iron, Iodine and Selenium Effects on Quality, Shelf Life and Microbial Activity of Cherry Tomatoes

Tomatoes have high nutritional and economical value and its deterioration start after harvest. They need proper treatments to increase and maintain quality as well as shelf life. The objective of this study was to determine the effect of iron, iodine and selenium on quality, shelf life and microbial activity of cherry tomatoes. Iron (1 mg/L), iodine (1 mg/L) and selenium (1 mg/L) were supplied with nutrient solution for five weeks prior to harvest. Then, cherry tomatoes were stored at  5 °C to assess quality, shelf life and microbial activity. The highest Ca content (p < 0.05) revealed in selenium-treated cherry tomatoes. Lower respiration and ethylene production were showed in selenium-treated cherry tomatoes both harvest time and after storage compared with iron and iodine treatments. At harvest time and after storage, the respiration were 1.29 (p < 0.05) and 0.62 mL/kg/hr (p < 0.01), respectively in selenium-treated cherry tomatoes. Moreover at harvest time and after storage in selenium-treated cherry tomatoes, the ethylene production was 2.11 and 0.87 μL/kg/hr (p < 0.01), respectively. The lowest fresh weight loss, the longest shelf life (p < 0.01), the least fungal incidence rate and microbial activities were found in selenium-treated cherry tomatoes. The longest shelf life of selenium-treated cherry tomatoeswas 22 days. Selenium-treated cherry tomatoes’ firmness increased (16.82N) at harvest time (p < 0.05) and it was significantly retained (12.70N) after storage (p < 0.01). Color development and lycopene content were more suppressed by selenium treatment after storage than iron and iodine treatments. Titratable acidity, vitamin C and soluble solids increased in selenium-treated cherry tomatoes after storage. Based on results, selenium-treated cherry tomatoes have significant potential to increase and maintain quality and shelf life

Supplementation of H1N1pdm09 Split Vaccine with Heterologous Tandem Repeat M2e5x Virus-like Particles Confers Improved Cross-Protection in Ferrets

Current influenza vaccines induce strain-specific immunity to the highly variable hemagglutinin (HA) protein. It is therefore a high priority to develop vaccines that induce broadly cross-protective immunity to different strains of influenza. Since influenza A M2 proteins are highly conserved among different strains, five tandem repeats of the extracellular peptide of M2 in a membrane-anchored form on virus- like particles (VLPs) have been suggested to be a promising candidate for universal influenza vaccine. In this study, ferrets were intramuscularly immunized with 2009 H1N1 split HA vaccine (“Split”) alone, influenza split vaccine supplemented with M2e5x VLP (“Split+M2e5x”), M2e5x VLP alone (“M2e5x”), or mock immunized. Vaccine efficacy was measured serologically and by protection against a sero- logically distinct viral challenge. Ferrets immunized with Split+M2e5x induced HA strain specific and conserved M2e immunity. Supplementation of M2e5x VLP to split vaccination significantly increased the immunogenicity of split vaccine compared to split alone. The Split+M2e5x ferret group showed evidence of cross-reactive protection, including faster recovery from weight loss, and reduced inflammation, as inferred from changes in peripheral leukocyte subsets, compared to mock-immunized animals. In addi- tion, ferrets immunized with Split+M2e5x shed lower viral nasal-wash titers than the other groups. Ferrets immunized with M2e5x alone also show some protective effects, while those immunized with split vaccine alone induced no protective effects compared to mock-immunized ferrets. These stud- ies suggest that supplementation of split vaccine with M2e5x-VLP may provide broader and improved cross-protection than split vaccine alone

Photoemission and x-ray absorption spectroscopy study of electron-doped colossal magnetoresistance manganite: La0.7Ce0.3MnO3 film

The electronic structure of La0.7Ce0.3MnO3 (LCeMO) thin film has been investigated using photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). The Ce 3d core-level PES and XAS spectra of LCeMO are very similar to those of CeO2, indicating that Ce ions are far from being trivalent. A very weak 4f resonance is observed around the Ce 4d $\to$ 4f absorption edge, suggesting that the localized Ce 4f states are almost empty in the ground state. The Mn 2p XAS spectrum reveals the existence of the Mn(2+) multiplet feature, confirming the Mn(2+)-Mn(3+) mixed-valent states of Mn ions in LCeMO. The measured Mn 3d PES/XAS spectra for LCeMO agrees reasonably well with the calculated Mn 3d PDOS using the LSDA+U method. The LSDA+U calculation predicts a half-metallic ground state for LCeMO.Comment: 7 pages, 7 figure

Performance Analysis of Multi-Antenna Hybrid Satellite-Terrestrial Relay Networks in the Presence of Interference

Abstract—The integration of cooperative transmission into satellite networks is regarded as an effective strategy to increase the energy efficiency as well as the coverage of satellite communications. This paper investigates the performance of an amplifyand-forward (AF) hybrid satellite-terrestrial relay network (HSTRN), where the links of the two hops undergo Shadowed- Rician andRayleigh fadingdistributions, respectively.By assuming that a single antenna relay is used to assist the signal transmission between the multi-antenna satellite and multi-antenna mobile terminal, and multiple interferers corrupt both the relay and destination, we first obtain the equivalent end-to-end signal-to-interference-plus-noise ratio (SINR) of the system. Then, an approximate yet very accurate closed-form expression for the ergodic capacity of the HSTRN is derived. The analytical lower bound expressions are also obtained to efficiently evaluate the outage probability (OP) and average symbol error rate (ASER) of the system. Furthermore, the asymptotic OP and ASER expressions are developed at high signal-to-noise ratio (SNR) to reveal the achievable diversity order and array gain of the considered HSTRN. Finally, simulation results are provided to validate of the analytical results, and show the impact of various parameters on the system performance