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Photosynthetic adaptations of polar phytoplankton to extreme low light
Full text linkPolar phytoplankton are vital to global aquatic ecosystems, driving primary production, biogeochemical cycling, carbon sequestration, biodiversity, and climate regulation. Polar phytoplankton’s slow but significant productivity at exceptionally low light suggests possible adaptations for low-light photosynthesis. We hypothesized that maintaining photosynthesis under extremely low light involves suppressing energetically wasteful charge recombinations in Photosystem II. These recombinations desynchronize the four-step cycle of Photosystem II oxygen evolution. We used single turnover variable chlorophyll fluorescence to detect changes in recombination in polar diatoms and green algae in response to temperature and photon delivery spacing. Prolonged synchronous cycling indicates fewer wasteful recombination reactions and, thus, more efficient photosynthetic energy conversion under low light. We observed that higher photon delivery rates and colder temperatures result in less recombination within taxa. Further, polar taxa synchronized cycles for longer durations than temperate taxa under comparable conditions. Our findings support our hypothesis that diverse polar phytoplankton have evolved capacities to suppress energetically wasteful charge recombinations and sustain photosynthesis under extremely low light. This research challenges the conventional understanding of the limits on photosynthesis under light limitation, helping unravel polar ecosystem dynamics and predict their ecosystem responses to climate change
A tunable approach to induce the formation of flexible nanofilms from small (3 nm) gold nanoparticles at oil/water interfaces
Full text linktype of work: Research Articlepublication status: This is the accepted version of a research article. The final version of the article is available here: https://doi.org/10.1021/acs.jpcb.3c0727
Synthesis, characterization, reactivity, and computational studies of a novel phosphinoboronate ester
Full text linkOnly in recent years have single bond phosphinoboronate esters gained attention as an efficient method to simultaneously add both a phosphino group and a boron group to unsaturated functionalities. To date only a handful have been
characterized and their reactivity remains underexplored. This work reports upon the
synthesis and reactivity of the novel phosphinoboronate ester Ph2PBbzpin (1, bzpin =
O2C2Ph4) with aldehydes, ketones, and a,b-unsaturated carbonyls. In general, it was found that most reactions result in 1,2-addition products with the formation of new P-C and B-O bonds. Novel reactivity is observed when bulkier ketones are employed and alternatively the formation of a boron enolate and free diphenyl phosphine are observed. Through experimental and computational studies, we found that product selectivity is highly dependent upon steric effects
Legacy effects of historical gold mining on chironomid assemblages from Gegogan Lake, Nova Scotia
Full text linkHistorical gold mining in Nova Scotia (NS), Canada, began in the 1860s, and released
contaminants into the environment through tailings that were transported by wind and surface
waters. I investigated the remains of benthic invertebrates and geochemical proxies archived in
the sediment of a shallow lake downstream from the province’s most productive historical gold
mine. Sedimentary concentrations of metal(loid)s were used to determine mining inputs of
tailings as well as establish the pre-mining and post-mining time periods within the lake
sediment record. Chironomid assemblages were assessed as an ecological response to long-term
environmental changes. Total mercury levels peaked at six times above the sediment quality
guidelines, and arsenic concentrations peaked at 165 times. Sedimentary contaminants have
declined but remain above probable effect levels. There was a significant difference (p = 0.001)
in assemblage compositions between the pre-mining and post-mining time periods. There were
seven indicator taxa in the pre-mining and three indicator taxa in the post-mining period. In the
pre-mining time period, there was an average of 1448 ± 186 chironomid head capsules per gram
of sediment which declined to an average of 355 ± 257 per gram in the post-mining time period.
The relative abundances of several metal(loid) tolerant chironomid taxa have increased in the
post-mining period. For example, during the pre-mining period Constempellina was present at an
average of 5% abundance and increased to 12% abundance post-mining. Findings from this
study show that pollution from historical gold mining continues to make its way into and
negatively affect the benthos of Gegogan Lak
Modelling the Containment of Viruses with Self-Disseminating Vaccines on Graphs
Full text linkAn increasingly prominent topic in the field of immunology is the objective of
limiting the spread of contagion in various animal populations. One recently presented
solution is the use of self-disseminating vaccines. Self-disseminating vaccines are
vaccines that are administered to small proportions of a large population of a species,
with the property that the vaccine spreads itself autonomously. The theory behind
their use is that at-risk populations could be identified, and then quickly inoculated
with the use of a sparse number of optimally-distributed vaccines. We study the
most efficient distributions of these vaccines on graphs, creating a model designed to
determine optimal strategies for their use. In particular, we determine the minimum
number of self-disseminating vaccines that must be used to contain the spread of a
virus or contagion on several infinite graphs, as well as the best way to use a single
selfdisseminating vaccine to preserve as much of a population from infection as possible
on several finite graph
Synthesis and computational studies of a novel tethered diindane
Full text linkThe Twelve Principles of Green Chemistry, which were developed by Anastas and Warner in 1998, seek to reduce environmental risks and wastes produced by chemical processes and products. One of these principles, catalysis, is key, as the use of chemical catalysts eliminates waste that would result from the use of stochiometric amounts of reactant. Because of their favorable redox properties, precious transition metals such as palladium and rhodium are essential components of homogeneous organometallic catalysts used in a variety of important industrial processes. However, these metals are expensive and toxic and have significant environmental impact. In contrast, the base main group metal indium is relatively non-toxic and inexpensive and has seen utility as a metal center in Lewis acid catalysts. Indium is stable primarily in the +3 oxidation state, which limits its utility in catalytic processes where oxidative addition/reductive elimination reactions are required. The current work seeks to synthesize and characterize the novel redox active diindane [(NCN)In]2(naphth) (6), which will ultimately be tested as a redox active green catalyst. The synthetic routes explored and the structural characterization of the novel compounds [(NCN)InBr]2 (5) and [LiBr(TMEDA)]2 are reported
Actions Speak Louder Than Coaches: Eating Disorder Behaviour Among Student Athletes
Full text linkThe objective of the current study was to examine the prevalence of eating disorder
behaviour among student athletes. Two hundred participants (130 female, 70 male)
completed an online survey that assessed participants eating disorder behaviour (EAT26),
behaviours consistent with the Adonis Complex (ACQ) and perceived social support
(modified MPSS). The results revealed significant differences in eating disorder
behaviour between female and male athletes, with females scoring significantly higher.
No differences were found between how female and male athletes scored on the Adonis
Complex Questionnaire. Significant differences were found between lean-sport and non
lean sport athletes, with lean sport athletes exhibiting more eating disorder behaviours.
Furthermore, non-lean sport male athletes were found to score significantly higher than
lean-sport male athletes for the Adonis Complex. Significant differences were also found
across club and varsity sports, with club athletes exhibiting significantly more eating
disorder behaviours than varsity athletes. Perceived social support was found to be
negatively correlated to eating disorder behaviour, and when considering gender
variables, level of competition and type of sport, accounted for unique variance in eating
disorder behaviour. These results suggest that athletes are susceptible to negative mental
health outcomes, and eating behaviours vary among athletes and sport type. The results
highlight the importance of having support systems in place for student athletes and
increasing awareness of athletic staff and coaches as to the seriousness and prevalence of
eating disorder behaviours among their student athlete
Impacts of historical gold mining on chironomid assemblages in lake Thomas, Nova Scotia.
Full text linkGold mining operations were one of the predominant economic activities in the Waverley
Gold District between the 1860s and 1940s. The mine tailings produced were transported into the
local environment and likely contributed to pollution of the Shubenacadie Canal drainage
basin. In this study, I used paleolimnological approaches to understand the long-term ecological
effects of historical gold mining operations on benthic invertebrates in Lake Thomas.
Sedimentary concentrations of total arsenic (As) and total mercury (Hg) were measured from a
dated sediment core to track pollution history. Subfossil chironomid remains were analyzed to
examine biological effects of mining pollution on the benthos. Sedimentary As and Hg levels
were low prior to gold mining activities; however, during the mining era concentrations of both
elements increased. Chironomid production declined by half from the pre-mining period and
suggests biological impacts from historical mining pollution. Chironomid assemblage
compositions between pre-mining and post-mining periods were significantly different
(p<0.003). Recent sediments showed mining-related contaminants were higher than national
sediment quality guidelines by ~12x for As and ~11x for Hg. Although the Waverley Gold
District was closed to mining eight decades ago, elevated contaminant levels from historical
mining may still be affecting the composition and production of aquatic biota associated with the
benthic habitat. My research contributes to the growing number of environmental assessments
that aim to understand the long-term ecological consequences of mining operations on aquatic
ecosystems
The effect of source credibility and similarity to participants on susceptibility to misinformation
Full text linkPrevious research exploring misinformation has established that source credibility and source
similarity to the information recipient are factors that can increase a source’s ability to mislead
someone (Chaiken & Maheswaran, 1994; Traberg and van der Linden, 2022). The purpose of the
present study is to investigate how people judge the veracity of factual information and
misinformation coming from sources varying in these qualities. The hypotheses were: (1)
misinformation from high-credibility sources will be most endorsed; (2) misinformation from
similar sources will be more endorsed than from dissimilar sources; and (3) factual information
from low-credibility, dissimilar sources will be dismissed. Participants (N = 93) were recruited
from a small undergraduate university. They viewed and rated the perceived truthfulness of 40
fabricated Instagram posts, including sixteen posts related to sexual violence whose sources
varied in ideology (feminist versus non-feminist) and credibility (high versus low credibility).
Participants completed a measure of feminist attitudes and were classified as being high-feminist
or low-feminist. Results indicated participants generally endorsed misinformation more from
high-credibility sources, and that both high- and low-feminist participants preferred similar
sources, being generally more willing to endorse misinformation from ideologically similar
sources. However, in an unexpected finding, participants endorsed misinformation from
non-feminist, low-credibility sources more than other sources, even those participants with a high
degree of feminist attitudes. Limitations and future considerations are discussed