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Articles 147961 - 147990 of 302772

Full-Text Articles in Physical Sciences and Mathematics

The Importance Of Supersaturated Silica Deposition For Base-Metalau-Ag Mineralisation In Western Turkey, Gülcan Bozkaya, David A. Banks Jan 2015

The Importance Of Supersaturated Silica Deposition For Base-Metalau-Ag Mineralisation In Western Turkey, Gülcan Bozkaya, David A. Banks

Turkish Journal of Earth Sciences

In the Arapuçandere LS-IS epithermal deposit in western Turkey, either well crystallised euhedral quartz or milky amorphous silica occurrences are associated with the precious and base-metal mineralisation. This study has determined the relative importance of the processes precipitating both of these in relation to the deposition of the ore. Analysis by LA-ICPMS of euhedral quartz and amorphous silica show that the latter is associated with much higher metal concentrations and suggests that the process responsible is more important for deposition of ore in the deposit. Mineralisation at Kumarlar and Koru may be similar. Slow cooling precipitates euhedral quartz and some …


Moving Towards A Greener Future: An Investigation Of How Transit-Oriented Development Has The Potential To Redefine Cities Around Sustainability, Margaret E. Smith Jan 2015

Moving Towards A Greener Future: An Investigation Of How Transit-Oriented Development Has The Potential To Redefine Cities Around Sustainability, Margaret E. Smith

Scripps Senior Theses

How does transportation shape the cities we live in? This paper takes a close look at the practice of transit-oriented development to assess its implications for the future of urban areas. Through the design of a hypothetical light rail station in the suburb of Redmond, WA, this paper demonstrates how targeting sustainable development around transit has the potential to influence entire towns to “go green,” and proposes that, moving forward, cities be designed to maximize mobility, livability, and sustainability.


Exploring How Social Media Can Be Used To Promote Space Awareness: A Case Study Of The Yuri's Night Web 2.0, Alan Steinberg, Jeffrey Alles, Ryan L. Kobrick Jan 2015

Exploring How Social Media Can Be Used To Promote Space Awareness: A Case Study Of The Yuri's Night Web 2.0, Alan Steinberg, Jeffrey Alles, Ryan L. Kobrick

Publications

Despite the importance of social media as an inexpensive and efficient means of communication, it is not clear to what degree space advocacy groups are making a strong organized effort to use the resources available to them. Moreover, there is no previous literature that specifically examines the use of social media tools by space organizations. This study seeks to start a larger dialog regarding how the space advocacy community can make use of these tools to promote their mission. Using a case study approach, this article focuses specifically on the organization of Yuri’s Night to explore how this group is …


The Effect Of Compact Object Spin On The Search For Gravitational Waves From Binary Neutron Star And Neutron Star-Black Hole Mergers, Alexander Harvey Nitz Jan 2015

The Effect Of Compact Object Spin On The Search For Gravitational Waves From Binary Neutron Star And Neutron Star-Black Hole Mergers, Alexander Harvey Nitz

Dissertations - ALL

In this dissertation we study gravitational-wave searches for

binary neutron star and neutron star - black hole coalescences.

We determine the accuracy of post-Newtonian approximations as gravitational-wave

templates in matched-filter based searches for NSBH mergers.

We test a geometric method to generate template banks for BNS and NSBH mergers where

the components have intrinsic spin, and estimate the sensitivity to

astrophysical sources of searches that use these banks during Advanced LIGO.

We explore simplifications and optimizations to the search pipeline used

during S6/VSR2,3 gravitational-wave searches. We investigate methods for regenerating

template banks as the noise behavior of a detector changes …


Comparing Bulk Aerosol Profiles In The Mixed Layer In Coastal Los Angeles And The Inland Empire, Taia Sean Wu Jan 2015

Comparing Bulk Aerosol Profiles In The Mixed Layer In Coastal Los Angeles And The Inland Empire, Taia Sean Wu

Scripps Senior Theses

Characteristic westerly sea breeze carries air over the Los Angeles Basin in Southern California to the Inland Empire approximately 50 miles inland, directly impacting air quality in both of these two highly polluted regions. As particles play a critical role in air quality and human health, this study compares the bulk aerosol profiles of the Los Angeles pollution "source" and Inland Empire "receptor" regions during the 2013 and 2014 NASA Student Airborne Research Program (SARP) campaigns onboard the NASA DC-8 airborne laboratory. The source and receptor regions were characterized by a series of missed approaches at the Los Angeles International …


Exploration Of Materials Used In 3-Dimensional Printing For The Dental Industry, Holly Chang Hayden Jan 2015

Exploration Of Materials Used In 3-Dimensional Printing For The Dental Industry, Holly Chang Hayden

Scripps Senior Theses

A limiting factor in the digitization of dental devices is the availability of materials suitable for use in both dentistry and the new digital technologies. As a rapidly growing industry, three-dimensional printing (3DP) has the potential to disrupt traditional manufacturing and prototyping methods. A review of both restorative materials and the current 3DP materials has lead to a focus on fiber- reinforced composites in the exploration for a new 3DP material. In addition, another area worth exploring and investing in would be 3D bioprinting as it opens up the possibility of regenerative dentistry.


Student Contributors -- Global Perspectives/Regional Solutions: A Public Journalism Project Curated, Peter Adams Jan 2015

Student Contributors -- Global Perspectives/Regional Solutions: A Public Journalism Project Curated, Peter Adams

OUR Journal: ODU Undergraduate Research Journal

[Editor note: This project is in the form of a Wordpress site containing interviews, articles and other materials by students in a public journalism course. The primary pages were saved as a pdf document for download. For the full text of student works, please see the full Wordpress site at: https://snaax123.wordpress.com/

from "About":
Welcome to a project of Public Journalism CRN 10745
Climate Change: Global Perspectives. Regional Solutions
Students have learned the fundamentals of journalism research and reporting. Students also examined issues surrounding climate change and sea-level rise globally and regionally in Hampton Roads.]


Studying The Effect Of Sea-Level Rise On Infrastructure And Construction, Michelle Flanagan Jan 2015

Studying The Effect Of Sea-Level Rise On Infrastructure And Construction, Michelle Flanagan

OUR Journal: ODU Undergraduate Research Journal

Climate Central, a nonprofit research organization that aims to provide the public with relevant and reliable information on climate change, developed an interactive application called the Risk Finder tool that launched in October of 2013. This tool collects data from several federal agencies, including NOAA, FEMA, and the EPA, and allows users to research sea-level rise and climate change in their specific state. In an effort to provide a user-friendly platform, Dan Rizza at Climate Central tasked an introductory Technical and Scientific writing course at Old Dominion University with conducting usability testing on the Risk Finder tool. Usability testing is …


A Study Of The Effects Of Usability On Risk Perception And User Affinity Of Risk Finder, Erin Jacobson Jan 2015

A Study Of The Effects Of Usability On Risk Perception And User Affinity Of Risk Finder, Erin Jacobson

OUR Journal: ODU Undergraduate Research Journal

In October 2013, Climate Central, a non-profit research organization, released Risk Finder, an online, interactive mapping tool that allows users to explore the effects of rising sea level in a specific geographic region. A research study for client Dan Rizza of Climate Central was conducted on the usability of the Risk Finder tool in an effort to identify potential system errors, improve user experience, and assess the future use of this tool based on user perception. Primary investigators Dr. Daniel Richards and Mrs. Megan McKittrick utilized an approach known as “productive usability,” which allows researchers to openly observe participants …


An Ion Detector For The Array For Nuclear Astrophysics And Structure With Exotic Nuclei (Anasen), Cedric Williams, K Macon, C M. Deibel, J C. Blackmon Jan 2015

An Ion Detector For The Array For Nuclear Astrophysics And Structure With Exotic Nuclei (Anasen), Cedric Williams, K Macon, C M. Deibel, J C. Blackmon

Honors Theses

No abstract provided.


Parallel Fabrication And Transport Properties Of Carbon Nanotube Single Electron Transistors, Muhammad Islam Jan 2015

Parallel Fabrication And Transport Properties Of Carbon Nanotube Single Electron Transistors, Muhammad Islam

Electronic Theses and Dissertations

Single electron transistors (SET) have attracted significant attention as a potential building block for post CMOS nanoelectronic devices. However, lack of reproducible and parallel fabrication approach and room temperature operation are the two major bottlenecks for practical realization of SET based devices. In this thesis, I demonstrate large scale single electron transistors fabrication techniques using solution processed single wall carbon nanotubes (SWNTs) and studied their electron transport properties. The approach is based on the assembly of individual SWNTs via dielectrophoresis (DEP) at the selected position of the circuit and formation of tunnel barriers on SWNT. Two different techniques: i) metal-SWNT …


Convective Heat Transfer In Quasi-One-Dimensional Magnetic Fluid In Horizontal Field And Temperature Gradients, Jun Huang Jan 2015

Convective Heat Transfer In Quasi-One-Dimensional Magnetic Fluid In Horizontal Field And Temperature Gradients, Jun Huang

Electronic Theses and Dissertations

In this work we studied the convective heat transfer in a magnetic fluid in both zero and applied magnetic fields. The natural convection is observed in a quasi-one dimensional magnetic fluid in a horizontal temperature gradient. The horizontal non-homogeneous magnetic fields were applied across the sample cell either parallel or anti-parallel to the temperature gradient. The temperature profile was measured by eight thermocouples and temperature sensitive paint. The flow velocity field and streamlines were obtained by optical flow method. Calculated Nusselt numbers, Rayleigh number, and Grashof number show that the convective flow is the main heat transfer mechanism in applied …


Structure-Property Relationship Of The Two-Photon Circular Dichroism Of Compounds With Axial And Helical Chirality, Carlos Diaz Jan 2015

Structure-Property Relationship Of The Two-Photon Circular Dichroism Of Compounds With Axial And Helical Chirality, Carlos Diaz

Electronic Theses and Dissertations

Back in 1894 Lord Kelvin coined the term "chiral" in order to refer to molecules whose mirror images were not superimposable with themselves. Over the years, research has demonstrated the important role that chiral molecules play in life, chemistry, and biology as well as their importance in the development of new drugs and technologies. The efforts to understand chiral systems have been mainly driven by spectroscopic methods that leverage on the opposite responses that enantiomers have to linear or circularly polarized light of both handedness. More specifically, Electronic Circular Dichroism (ECD) which measures the differences in linear absorption of left …


Fast Strain Wave Induced Magnetization Changes In Long Cobalt Bars: Domain Motion Versus Coherent Rotation, S Davis, J A. Borchers, B B. Maranville, Shireen Adenwalla Jan 2015

Fast Strain Wave Induced Magnetization Changes In Long Cobalt Bars: Domain Motion Versus Coherent Rotation, S Davis, J A. Borchers, B B. Maranville, Shireen Adenwalla

Department of Physics and Astronomy: Faculty Publications

A high frequency (88 MHz) traveling strain wave on a piezoelectric substrate is shown to change the magnetization direction in 40 lm wide Co bars with an aspect ratio of 103. The rapidly alternating strain wave rotates the magnetization away from the long axis into the short axis direction, via magnetoelastic coupling. Strain-induced magnetization changes have previously been demonstrated in ferroelectric/ferromagnetic heterostructures, with excellent fidelity between the ferromagnet and the ferroelectric domains, but these experiments were limited to essentially dc frequencies. Both magneto-optical Kerr effect and polarized neutron reflectivity confirm that the traveling strain wave does rotate the magnetization away …


Continuous Third Harmonic Generation In A Terahertz Driven Modulated Nanowire, Kathleen E. Hamilton, Alexey Kovalev, Amrit De, Leonid P. Pryadko Jan 2015

Continuous Third Harmonic Generation In A Terahertz Driven Modulated Nanowire, Kathleen E. Hamilton, Alexey Kovalev, Amrit De, Leonid P. Pryadko

Department of Physics and Astronomy: Faculty Publications

We consider the possibility of observing continuous third-harmonic generation using a strongly driven, single-band one-dimensional metal. In the absence of scattering, the quantum efficiency of frequency tripling for such a system can be as high as 93%. Combining the Floquet quasienergy spectrum with the Keldysh Green’s function technique, we derive a semiclassical master equation for a one-dimensional band of strongly and rapidly driven electrons in the presence of weak scattering by phonons. The power absorbed from the driving field is continuously dissipated by phonon modes, leading to a quasi-equilibrium in the electron distribution. We use the Kronig-Penney model with varying …


Thresholds For Correcting Errors, Erasures, And Faulty Syndrome Measurements In Degenerate Quantum Codes, Ilya Dumer, Alexey Kovalev, Leonid P. Pryadko Jan 2015

Thresholds For Correcting Errors, Erasures, And Faulty Syndrome Measurements In Degenerate Quantum Codes, Ilya Dumer, Alexey Kovalev, Leonid P. Pryadko

Department of Physics and Astronomy: Faculty Publications

We suggest a technique for constructing lower (existence) bounds for the fault-tolerant threshold to scalable quantum computation applicable to degenerate quantum codes with sublinear distance scaling. We give explicit analytic expressions combining probabilities of erasures, depolarizing errors, and phenomenological syndrome measurement errors for quantum low-density parity-check codes with logarithmic or larger distances. These threshold estimates are parametrically better than the existing analytical bound based on percolation.


Spin Glass Reflection Of The Decoding Transition For Quantum Error Correcting Codes, Alexey Kovalev, Leonid P. Pryadko Jan 2015

Spin Glass Reflection Of The Decoding Transition For Quantum Error Correcting Codes, Alexey Kovalev, Leonid P. Pryadko

Department of Physics and Astronomy: Faculty Publications

We study the decoding transition for quantum error correcting codes with the help of a mapping to random-bond Wegner spin models. Families of quantum low density parity-check (LDPC) codes with a finite decoding threshold lead to both known models (e.g., random bond Ising and random plaquette Z2 gauge models) as well as unexplored earlier generally non-local disordered spin models with non-trivial phase diagrams. The decoding transition corresponds to a transition from the ordered phase by proliferation of "post-topological" extended defects which generalize the notion of domain walls to non-local spin models. In recently discovered quantum LDPC code families with …


Relativistic Configuration Interaction Calculations Of The Atomic Properties Of Selected Transition Metal Positive Ions; Ni Ii, V Ii And W Ii, Marwa Hefny Abdalmoneam Jan 2015

Relativistic Configuration Interaction Calculations Of The Atomic Properties Of Selected Transition Metal Positive Ions; Ni Ii, V Ii And W Ii, Marwa Hefny Abdalmoneam

Dissertations, Master's Theses and Master's Reports

Relativistic Configuration Interaction (RCI) method has been used to investigate atomic properties of the singly ionized transition metals including Nickel (Ni II), Vanadium (V II), and Tungsten (W II). The methodology of RCI computations was also improved. Specifically, the method to shift the energy diagonal matrix of the reference configurations was modified which facilitated including the effects of many electronic configurations that used to be difficult to be included in the energy matrix and speeded-up the final calculations of the bound and continuum energy spectrum. RCI results were obtained for three different cases:

  1. Atomic moments and polarizabilities of Ni II; …


Determination Of Inhibitor Specificity For Low Molecular Weight Protein Tyrosine Phosphatase Isoforms A And B, Erica K. Sinner Jan 2015

Determination Of Inhibitor Specificity For Low Molecular Weight Protein Tyrosine Phosphatase Isoforms A And B, Erica K. Sinner

Honors Theses, 1963-2015

The two active isoforms of Low Molecular Weight Protein Tyrosine Phosphatase (LMW-PTP) have inverse cellular effects on cancer. Isoform A has been found to be anti-oncogenic, while overexpression of Isoform B is oncogenic. Inhibitors of Isoform B could have anti-cancer effects, however, it is of utmost importance that these inhibitors exhibit specificity for Isoform B and do not affect the function of Isoform A. Isoform A was recombinantly expressed, purified and characterized in order to compare its structure and function to Isoform B. It is hoped that this characterization, along with the synthesis and screening of potential inhibitors for both …


Cyberspace: A Venue For Terrorism, David Bieda, Leila Halawi Jan 2015

Cyberspace: A Venue For Terrorism, David Bieda, Leila Halawi

Publications

This paper discusses how cyberspace has become a venue for terrorists groups for recruiting and proliferating propaganda and terrorism. Moreover, this study explores how the low cost Internet infrastructure and social media sites (such as Facebook, Twitter, and YouTube) have contributed to their networking and operations due to the convenience, in terms of availability, accessibility, message redundancy, ease of use, and the inability to censor content. Concepts such as cyber-weapons, cyber-attacks, cyber-war, and cyber-terrorism are presented and explored to assess how terrorist groups are exploiting cyberspace.


Bimetallic Complexes Supported By A Redox-Active Ligand With Fused Pincer-Type Coordination Sites, Denan Wang, Sergey Lindeman, Adam T. Fiedler Jan 2015

Bimetallic Complexes Supported By A Redox-Active Ligand With Fused Pincer-Type Coordination Sites, Denan Wang, Sergey Lindeman, Adam T. Fiedler

Chemistry Faculty Research and Publications

The remarkable chemistry of mononuclear complexes featuring tridentate, meridionally chelating “pincer” ligands has stimulated the development of ligand frameworks containing multiple pincer sites. Here, the coordination chemistry of a novel pentadentate ligand (LN3O2) that provides two closely spaced NNO pincer-type compartments fused together at a central diarylamido unit is described. The trianionic LN3O2 chelate supports homobimetallic structures in which each M(II) ion (M = Co, Cu, Zn) is bound in a meridional fashion by the bridging diarylamido N atom and O,N-donors of the salicyaldimine arms. The metal centers are also coordinated by a mono- or bidentate …


Synthesis Of Unnatural Amino Acids For Genetic Encoding By The Pyrrolysyl-Trna/Rna Synthetase System, William A. Knight Jan 2015

Synthesis Of Unnatural Amino Acids For Genetic Encoding By The Pyrrolysyl-Trna/Rna Synthetase System, William A. Knight

Theses and Dissertations

The complexity of all biomolecules in existence today can be attributed to the variation of the amino acid repertoire. In nature, 20 canonical amino acids are translated to form these biomolecules, however, many of these amino acids have revealed posttranslational modifications (i.e. acetylation, methylation) after incorporation. Amino acids that exhibit PTM are known for their involvement in cellular processes such as DNA repair and DNA replication; these PTMs are commonly found on histones within the chromatin complex. Utilization of in vivo site-specific incorporation has recently reported functionality of post-translationally modified amino acids.1 xii Here we report the synthesis and in …


Applications Of Stability Analysis To Nonlinear Discrete Dynamical Systems Modeling Interactions, Jonathan L. Hughes Jan 2015

Applications Of Stability Analysis To Nonlinear Discrete Dynamical Systems Modeling Interactions, Jonathan L. Hughes

Theses and Dissertations

Many of the phenomena studied in the natural and social sciences are governed by processes which are discrete and nonlinear in nature, while the most highly developed and commonly used mathematical models are linear and continuous. There are significant differences between the discrete and the continuous, the nonlinear and the linear cases, and the development of mathematical models which exhibit the discrete, nonlinear properties occurring in nature and society is critical to future scientific progress. This thesis presents the basic theory of discrete dynamical systems and stability analysis and explores several applications of this theory to nonlinear systems which model …


A Continuous Process Towards The Synthesis Of Quinolones, Stevara N. Clinton Jan 2015

A Continuous Process Towards The Synthesis Of Quinolones, Stevara N. Clinton

Theses and Dissertations

Abstract

The development of quinolones is described from the first quinolone to the latest fluoroquinolones. Quinolones have generated considerable interest since their discovery because of their antibacterial capabilities. Analogs incorporating the 4-quinolone ring system comprise a largely expanding group of synthetic compounds. The development of antibacterial resistance has created the need for an efficient synthesis of quinolones that can be easily adapted toward the assembly of quinolone based antibacterial drugs.

There are several reported approaches to the 4-quinolone ring system. Many of these methods use expensive starting materials, require the removal of high boiling solvents, or use high temperature conditions …


Domination Numbers Of Semi-Strong Products Of Graphs, Stephen R. Cheney Jan 2015

Domination Numbers Of Semi-Strong Products Of Graphs, Stephen R. Cheney

Theses and Dissertations

This thesis examines the domination number of the semi-strong product of two graphs G and H where both G and H are simple and connected graphs. The product has an edge set that is the union of the edge set of the direct product of G and H together with the cardinality of V(H), copies of G. Unlike the other more common products (Cartesian, direct and strong), the semi-strong product is neither commutative nor associative.

The semi-strong product is not supermultiplicative, so it does not satisfy a Vizing like conjecture. It is also not submultiplicative so it shares these two …


Cellulose, Chitosan, And Keratin Composite Materials. Controlled Drug Release, Chieu D. Tran, Tamutsiwa Moven Mututuvari Jan 2015

Cellulose, Chitosan, And Keratin Composite Materials. Controlled Drug Release, Chieu D. Tran, Tamutsiwa Moven Mututuvari

Chemistry Faculty Research and Publications

A method was developed in which cellulose (CEL) and/or chitosan (CS) were added to keratin (KER) to enable [CEL/CS+KER] composites to have better mechanical strength and wider utilization. Butylmethylimmidazolium chloride ([BMIm+Cl]), an ionic liquid, was used as the sole solvent, and because the [BMIm+Cl] used was recovered, the method is green and recyclable. Fourier transform infrared spectroscopy results confirm that KER, CS, and CEL remain chemically intact in the composites. Tensile strength results expectedly show that adding CEL or CS into KER substantially increases the mechanical strength of the composites. We found …


Epr Methods For Biological Cu(Ii): L-Band Cw And Nars, Brian Bennett, Jason M. Kowalski Jan 2015

Epr Methods For Biological Cu(Ii): L-Band Cw And Nars, Brian Bennett, Jason M. Kowalski

Physics Faculty Research and Publications

Abstract: Copper has many roles in biology that involve the change of coordination sphere and/or oxidation state of the copper ion. Consequently, the study of copper in heterogeneous environments is an important area in biophysics. EPR is a primary technique for the investigation of paramagnetic copper, which is usually the isolated Cu(II) ion, but sometimes as Cu(II) in different oxidation states of multitransition ion clusters. The gross geometry of the coordination environment of Cu(II) can often be determined from a simple inspection of the EPR spectrum, recorded in the traditional X-band frequency range (9–10 GHz). Identification and quantitation of the …


The Role Of Citizens In Detecting And Responding To A Rapid Marine Invasion, Steven B. Scyphers, Sean P. Powers, J. Lad Akins, J. Marcus Drymon, Charles W. Martin, Zeb H. Schobernd, Pamela J. Schofield, Robert L. Shipp, Theodore S. Switzer Jan 2015

The Role Of Citizens In Detecting And Responding To A Rapid Marine Invasion, Steven B. Scyphers, Sean P. Powers, J. Lad Akins, J. Marcus Drymon, Charles W. Martin, Zeb H. Schobernd, Pamela J. Schofield, Robert L. Shipp, Theodore S. Switzer

University Faculty and Staff Publications

Documenting and responding to species invasions requires innovative strategies that account for ecological and societal complexities. We used the recent expansion of Indo-Pacific lionfish (Pterois volitans/miles) throughout northern Gulf of Mexico coastal waters to evaluate the role of stakeholders in documenting and responding to a rapid marine invasion. We coupled an online survey of spearfishers and citizen science monitoring programs with traditional fishery-independent data sources and found that citizen observations documented lionfish 1–2 years earlier and more frequently than traditional reef fish monitoring programs. Citizen observations first documented lionfish in 2010 followed by rapid expansion and proliferation in …


Spatial Analyses On Seismo-Ionospheric Precursors Observed By Gim Tec And Demeter During The 2008 M8.0wenchuan Earthquake, Jann-Yenq Liu, Yuh-Ing Chen, Cheng-Chi Huang, Michel Parrot, Sergey Pulintets, Dimitar Ouzounov Jan 2015

Spatial Analyses On Seismo-Ionospheric Precursors Observed By Gim Tec And Demeter During The 2008 M8.0wenchuan Earthquake, Jann-Yenq Liu, Yuh-Ing Chen, Cheng-Chi Huang, Michel Parrot, Sergey Pulintets, Dimitar Ouzounov

Mathematics, Physics, and Computer Science Faculty Articles and Research

An abstract of the "Spatial analyses on seismo-ionospheric precursors observed by GIM TEC and DEMETER during the 2008 M8.0Wenchuan earthquake" paper presented at EGU General Assembly in 2015.


Chemoenzymatic Studies To Enhance The Chemical Space Of Natural Products, Jhong-Min Chen Jan 2015

Chemoenzymatic Studies To Enhance The Chemical Space Of Natural Products, Jhong-Min Chen

Theses and Dissertations--Pharmacy

Natural products provide some of the most potent anticancer agents and offer a template for new drug design or improvement with the advantage of an enormous chemical space. The overall goal of this thesis research is to enhance the chemical space of two natural products in order to generate novel drugs with better in vivo bioactivities than the original natural products.

Polycarcin V (PV) is a gilvocarcin-type antitumor agent with similar structure and comparable bioactivity with the principle compound of this group, gilvocarcin V (GV). Modest modifications of the polyketide-derived tetracyclic core of GV had been accomplished, but the most …