Brock University Digital Repository
Brock University's Digital Repository is an online archive showcasing and preserving the Brock community's scholarly output as well as items from the Library's Archives & Special Collections. Researchers can disseminate their work by depositing it in this Open Access repository, which provides free, immediate access to users while also allowing Brock scholars to track downloads and views of their scholarship. The Digital Repository is also the home of the Brock University E-Thesis Portal.
For more information, see the repository's policies and procedures.
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Recent Submissions
On the Optical Properties of the Misfit Layer Compound (PbSe)1+δ(NbSe2)n
(Brock University) Respicio, Paul Carlo; Reedyk, Maureen; Department of Physics
Misfit layer compounds (MLCs) are layered materials that consist of two different sublattices with a mismatch in at least one of their lattice parameters. This incommensurate mismatch along with charge transfer between the constituent sublattices gives rise to interesting properties and can potentially be tuned for practical applications. These systems can be understood using the framework of rigid band model and the changes in band filling depending on the extent of interlayer charge transfer.
This thesis presents the optical properties of (PbSe)1+δ(NbSe2)n and their evolution as the number of NbSe2 layers, n, are varied. NbSe2 is a known transition metal dichalcogenide superconductor and PbSe is a semiconductor with a rocksalt structure. NbSe2 and n=1-3 samples were synthesized via chemical vapour transport and characterized via X-ray diffraction, energy dispersive X-ray spectroscopy, and atomic force microscopy. Further characterization from resistivity and magnetization measurements showed a decrease in the superconducting transition temperature, Tc, with decreasing n. Reflectivity measurements were analyzed using the Drude-Lorentz model and reveal a shift in the plasma frequency to lower energies as n decreases along with the broadening of their interband transitions when compared to pure NbSe2. This behaviour is consistent with increased band filling due to charge transfer from PbSe to NbSe2. Optical conductivity functions were obtained using Kramers-Kronig analysis confirm decreased conductivity for the MLCs and follow a similar pattern found in the resistivity measurements. Finally, frequency-dependent scattering rate and effective mass were obtained from the extended Drude model. Results show a region of purely Drude response in the scattering rate for the MLCs and a trend of decreasing mass enhancement with decreasing n at low wavenumber.
Determining the Roles of the Aldehyde Dehydrogenase Enzymes 5 and 6 during Icewine and Table Wine Fermentation in a Commercial Wine Yeast Using CRISPR-Cas9.
(Brock University) Ott-Peon, Nadine; Inglis, Debra; Centre for Biotechnology
Canada is known for Icewine which is fermented from grapes naturally frozen on the vine. Grapes are harvested below –8°C and pressed while frozen, trapping ice crystals inside the
berries and releasing juice highly concentrated in sugars and acids. The high sugar juice environment (40°Brix) causes hyperosmotic stress for yeast, resulting in water loss, triggering
glycerol production to act as an internal osmolyte to draw water back into the yeast cell, resulting in an NAD+ imbalance. Icewine has significantly higher acetic acid versus table wine, where acetic acid production may be used to reduce NAD(P)+ to NAD(P)H via NAD(P)+-dependent aldehyde dehydrogenase proteins (Aldp). Previous research linked the NAD+ redox imbalance during Icewine fermentation with ALD gene expression patterns indicating a role of Ald3p encoded by ALD3 in elevating the acetic acid whereas in table wine, ALD6 expression
dominated. In the overall research program from our laboratory, the goal is to remove all five of the ALD genes, individually and in combination, from a commercial yeast genome using
CRISPR-Cas9 gene editing. The objective of this project is to remove three (ALD6, ALD5, and ALD4) of the five ALD genes individually from the genome of a commercial wine yeast K1
V1116 using CRISPR-Cas9 gene editing to assess the roles of the aldehyde dehydrogenase enzymes in acetic acid production in both Icewine and table wine using these commercial yeast
deletion strains. All copies of ALD6 and ALD5 were successfully knocked out of K1-V1116. The ald6Δ yeast had a significant impact on the acetic acid production with an 86% decrease in acetic acid production during Icewine fermentation and an 85% decrease during table wine fermentation in comparison to the wild-type control yeast. The ald5Δ had a significant but
minimal impact on acetic acid production during table wine fermentation and no impact on acetic acid during Icewine fermentation. Under table wine conditions, ald5Δ had a 16% decrease in acetic acid production. One allele of the ALD4 gene was successfully knocked out of K1-V1116, creating a heterozygous ALD4 mutant. This heterozygous mutant was not evaluated in
fermentations.
The Press, Volume 30, Issue 12, November 4, 1993
(1993-11-04) Cole, David T. (Editor); Mathieu, Nick (News Editor); Flannigan, Maurine (Features Editor); Bauer, Lisa (Arts and Entertainment Editor); Healey, Craig (Sports Editor); Antoniou, Jim (Photo Editor); Nickles, Greg (Illustration); Woodward, Paula (Advertsing Director); Dunsburger, Al (News Assistant); Zouganelis, George (Research Editor); Guzda, David (Entertainment Assistant); Pineault, Mike (Sports Assistant); Moreau, Shawn (Photo Assistant); Noll, Paul (Production Manager); McAllister, Randy (Advertising Assistant)
The Press, Volume 30, Issue 12 includes: Apathy becomes the political norm at Brock; BUSU decision to move polling booth may have changed outcome of referendum; Brock fraternity becomes official; Health fair ’93 a heart-stopping success; U of T laboratories killed 42,000 animals in 1992; Student wins Miss Canada pageant;
Reactions to Jean Cretien as new Canada PM; Sesame Street article;
Sexual abuse survivors take on the Canadian Supreme Court; November event calendar; The Brock Press’ Nick Matthieu interviews bassist; Article on Marvel Comics; Brock hockey team loses to Laurier; Women's basketball team shows promise.
The Press, Volume 30, Issue 11, October 28, 1993
(1993-10-28) Cole, David T. (Editor); Mathieu, Nick (News Editor); Monaghan, Scott (Features Editor); Bauer, Lisa (Arts and Entertainment Editor); Healey, Craig (Sports Editor); Antoniou, Jim (Photo Editor); Nickles, Greg (Illustration); Woodward, Paula (Advertising Director); Trumper, Charles (News Assistant); Zouganelis, George (Research Editor); Guzda, DAvid (Entertainment Assistant); Moreau, Shawn (Photo Assistant); Noll, Paul (Production Manager); McAllister, Randy (Advertsing Assistant); Rogers-Watson, Chris (Writer)
The Press, Volume 30, Issue 11 includes: Quebec separatism versus federalism; Students approve of everything on the BUSU referendum;
Government taxes textbooks; Thorold approves continued bus service to Brock; Brock students react to federal election; Expensive new roof added to Brock to prevent leaks; Math and computer science departments move to newly completed J-Block; Anti-Semitism Brock in letters to the editor; International selfishness devastates Haiti opinion; Collectability of comic books; Brock lacrosse team wins big at Guelph; Brock men’s hockey team crushes York University.
The Press, Volume 30, Issue 10, October 21, 1993
(1993-10-21) Cole, David T. (Editor); Mathieu, Nick (News Editor); Ward, Don (Features Editor); Bauer, Lisa (Arts and Entertainment Editor); Healey, Craig (Sports Editor); Antoniou, Jim (Photo Editor); Nickles, Greg (Illustration); Woodward, Paula (Advertsing Director); Rothwell, Fred (News Assistant); Zouganelis, George (Research Editor); Guzda, David (Entertainment Assistant); Moreau, Shawn (Photo Assistant); Noll, Paul (Production Manager); McAllister, Randy (Advertsing Assistant)
The Press, Volume 30, Issue 10 includes: Line to get into Isacc’s; Brock hosts second round of debates for federal candidates; Alcohol awareness week; 95% of Queen’s students approve of OUSA fee levy; Graduate experience at Brock given high marks; Details on all-candidate debate; BUSU “bungles” election; Brock swimmers start season with a splash.