Dissecting the quasar main sequence: insight from host galaxy properties

The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical FeII strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/L_Edd) of the black hole (BH) accretion. Shen & Ho demonstrated with quasar clustering analysis that the average BH mass decreases with increasing FeII strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion sigma* (hence the BH mass via the M-sigma* relation) from decomposed host spectra in low-redshift Sloan Digital Sky Survey quasars. We found that at fixed quasar luminosity, sigma* systematically decreases with increasing FeII strength, confirming that Eddington ratio increases with FeII strength. We also found that at fixed luminosity and FeII strength, there is little dependence of sigma* on the broad Hbeta FWHM. These new results reinforce the framework put forward by Shen & Ho that Eddington ratio and orientation govern most of the diversity seen in broad-line quasar properties.Comment: ApJL in press; 5 pages and 4 figure

Metabolic engineering and elucidation of the terpenoid indole alkaloid pathway in Catharanthus roseus hairy roots

2016 Summer.Includes bibliographical references.Catharanthus roseus (Madagascar periwinkle) produces many pharmaceutically important chemicals such as vinblastine, vincristine, serpentine, and ajmalicine. They are synthesized through the highly branched and complex terpenoid indole alkaloids (TIA) pathway in C. roseus. Among these TIAs, vinblastine and vinblastine, which are solely extracted from C. roseus, are the efficient anti-cancer drugs widely used in the clinic. However, due to the low accumulation of these TIAs within the plant and the industrial infeasibility of production using chemical synthesis, the market price of these drugs still remain high, and the production is inconsistent. With the advanced knowledge of molecular biology, metabolic engineering and bioinformatics, building a robust and efficient alternative production platform by manipulating the TIA pathway has become a major trend and promising strategy in recent research. However, many biosynthetic enzymes in TIA pathway and the regulation of the pathway are still poorly understood which impedes the rational engineering of this plant for enhanced TIA production. This thesis first uses advanced high-throughput sequencing technology to study the global transcriptional alterations after overexpressing a rate-limiting enzyme anthranilate synthase (AS) in the pathway. This study helps to increase understanding of TIA regulation in this transgenic hairy root line from a broader perspective. Furthermore, transcriptome sequencing of this unique transgenic line under three different conditions (uninduced control, induced AS overexpression, and methyl jasmonate elicitation) is analyzed using hierarchical clustering. A 200 candidate transcripts set was identified for the pathway genes located around the tabersonine branch point. Six cytochrome P450 monooxygenase candidates are selected for the unknown tabersonine 6,7 epoxidase that can convert tabersonine to lochnericine in C. roseus hairy roots. Meanwhile, effort on genetic modification of C. roseus hairy roots for TIA production using two different strategies are reported here. The first strategy helps establish a transgenic hairy root line with significantly increased TIA accumulation of all measure alkaloids by co-expressing the positive transcription factor ORCA3 (AP2-domain DNA-binding protein 3) and a pathway gene strictosidine glucosidase (SGD) that is not controlled by ORCA3. Since C. roseus hairy roots do not produce detectable vinblastine and vincristine due to the absence of the vindoline pathway, the second strategy initiated the effort to introduce the pathway by engineering the first two enzymes in C. roseus hairy root. Overexpression of these two genes, tabersonine 16-hydroxylase (T16H) and 16-O-methyl transferase (16OMT), leads to the accumulation of the expected vindoline pathway intermediates 16-hydroxytabersonine and 16-methoxytabersonine but not vindoline. Interestingly, the overexpression of these two genes influences the root native metabolite levels, triggers the altered transcription of TIA genes, and leads to the production of two new unknown metabolites. Overall, studies in this thesis not only contribute new transcriptome information to current publicly available databases, but also facilitate elucidating the TIA pathway and its complex regulation. This thesis also provides a metabolic engineering approach to enhance alkaloid production in C. roseus hairy roots by simultaneously overexpressing ORCA3 and SGD. Genetic modification of T16H and 16OMT in C. roseus hairy roots promisingly leads to the production of vindoline pathway intermediates. It also emphasizes some potential complexities for the future attempts to express the full vindoline pathway in hairy roots

Impact of Online Learning on International Students’ English Language Concerns

With the onset of COVID-19, U.S. universities have been forced to move many, even all, courses online. At the University of Richmond, many of our international students faced visa restrictions due to COVID and were required to stay in their countries. As a result, the majority of our international students must attend their classes remotely. International students may find language to be a challenge during online learning. The purpose of our study is to learn more about how, if at all, online classes have an impact on international students’ English language concerns

Sovereign Wealth Funds: Ein Branchenüberblick

Staatsfonds haben sich in den vergangenen Jahren zu bedeutenden Akteuren auf den internationalen Finanzmärkten entwickelt. Während sie in der Vergangenheit eher selten in Erscheinung getreten sind, rückten sie seit dem Jahr 2007 durch einige milliardenschwere Beteiligungen an westlichen Unternehmen schlagartig in den Fokus des öffentlichen Interesses. Staatsfonds weisen eine nach absoluten und relativen Maßstäben beachtliche Größe auf, wodurch sie verstärkt auch systemisch relevant werden. Das Papier gibt einen aktuellen Überblick über die Zusammensetzung der Staatsfondsindustrie und analysiert diese sowohl global als auch regionenspezifisch. Ferner werden auf Basis ausgewählter Prognosemodelle Tendenzaussagen zum Wachstum der Staatsfondsindustrie abgeleitet. Es zeigt sich, dass mit einer weiterhin expansiven Entwicklung zu rechnen ist. -- Sovereign Wealth Funds emerged as major players on the international financial markets within the last years. Whereas in the past they were hardly visible, Sovereign Wealth Funds have appeared in public since 2007 due to their heavy investments in Western corporations. By now Sovereign Wealth Funds absolutely and relatively show a remarkable size and thus have become systemically relevant. The Paper provides an up to date survey of the composition of the Sovereign Wealth Funds industry and gives a global and regional analysis. Furthermore several models are introduced to evaluate the prospective growth potential of the industry. A persistent expansion can be forecasted.Sovereign Wealth Funds,Staatsfonds

Upper Ocean Physical and Biological Response to Typhoon Cimaron (2006) in the South China Sea

The physical dynamic and biological response processes to Typhoon Cimaron (2006) in the South China Sea are investigated through the three‐dimensional Regional Ocean Modeling System (ROMS). For sea surface temperatures, ROMS achieves a correlation of more than 0.84, with respect to satellite observations, indicating a generally high level of skill for simulating the sea surface temperature variations during Typhoon Cimaron (2006). However, detailed analysis shows that ROMS underestimates the sea surface temperature cooling and mixed layer deepening because of insufficient mixing in the model simulations. We show that the simulation accuracy can be enhanced by adding a wave‐induced mixing term (BV) to the nonlocal K‐profile parameterization (KPP) scheme. Simulation accuracy is needed to investigate nutrients, which are deeply entrained to the oligotrophic sea surface layer by upwelling induced by Typhoon Cimaron, and which plays a remarkable role in the subsequent phytoplankton bloom. Simulations show that the phytoplankton bloom was triggered 5 days after the passage of the storm. The surface ocean was restored to its equilibrium ocean state by about 10–20 days after the typhoon\u27s passage. However, on this time‐scale, the resulting concentrations of nitrate and chlorophyll a remained higher than those in the pre-typhoon equilibrium

Hemicellulose-g-PAAc/TiO2 Nanocomposite Hydrogel for Dye Removal

Dyes pollution on urban environment is of great concern because of the human health hazards associated with this kind of contaminants, and the use of low-cost photocatalytic composite material is an efficient treatment method to minimize the environmental impact. A novel hemicellulose-g-PAAc/TiO2 composite hydrogel was prepared as a promising alternative material for dye removal. Wheat straw hemicellulose and TiO2 nanoparticles were first modified and then incorporated into hydrogel via covalent bonds. Effects of gel dosage, pH, initial concentration and contact time on the adsorption amount of methylene blue were systematically studied using the prepared hydrogel. The equilibrium adsorption data was fitted well to the Freundlich isotherm model, and Langmuir isotherm analysis indicated that the adsorption capacity of the hemicellulose-g-PAAc/TiO2 composite hydrogel was 389.1 mg/g, and adsorption kinetic study showed that the adsorption process can be described by the pseudo second-order kinetic model. The prepared composite hydrogel exhibited high photodegradation ability for methylene blue under alkaline conditions, and all results indicated that the hemicellulose-g-PAAc/TiO2 composite hydrogel had excellent photocatalytic degradability for dyes, which can be used in practical process

Comparative Investigations from Tribological and Corrosion Properties of Alumina and Nickel-Alumina Coatings on Cast Iron

Plasma Electrolytic Aluminating (PEA) Alumina coating on cast iron has a high wear/ corrosion resistance, but porous structure could cause pitting corrosion. Nickel is a widely used anti-corrosion material, but the wear resistance of nickel could still be developed. To explore advantages and disadvantages of combination of these two materials, electroless Nickel plating was applied on PEA Alumina coating. Electroless plated Ni grew from the interface of the alumina coating and cast iron and then sealed the micropores of the alumina coating in a nickel acetate bath, which could protect cast iron substrate from the pitting corrosion. In addition, some PEA Alumina coated samples were 500 °C heat treated to observe differences between unheated and heated samples in chemical composition and wear behaviours. The microstructure, chemical composition and phase structure of the coatings were investigated with scanning electron microscope (SEM), Energy-Dispersive X-Ray Spectroscopy (EDX) and X-ray diffraction (XRD). The tribology test data was from Pin-on-Disk (POD) dry sliding tests, and the corrosion resistance was evaluated by Open Circuit Potential (EOC), Potential Resistance (Rp), and electrochemical impedance spectroscopy (EIS) tests. Comparing with as-coated PEA Alumina coating, 500 °C heated sample had a higher oxygen content and worse wear behaviours. The Alumina coated sample had a lower coefficient of friction (COF) and longer durability. Ni-Alumina coating had a better corrosion resistance but slightly lower wear resistance. Thus, Ni-Alumina coating can benefit in wet corrosion environment, and the Alumina only coating can have a lower friction at the dry sliding condition