Showing 91 - 100 of 583 Items
Synthesis of N-Heterocyclic Carbene Complexes of Coinage Metals and Their Application in the Activation of Hydrogen
Date: 2024-01-01
Creator: Maryam Akramova
Access: Open access
- The main cause of the ongoing global climate crisis is the emission of greenhouse gases, and current climate reports emphasize the need to transition to low-emission renewable energy sources. Urgently needed are methods for storing renewable energy, such as synthetic fuels like hydrogen (H2) gas; however, a challenge to the widespread implementation of hydrogen fuel is its low volumetric energy density. This thesis describes an effort to synthesize a catalyst that takes advantage of hard-soft acid-base (HSAB) mismatches to activate H2 and facilitate its reaction with CO2 to form hydrocarbon fuels, thereby providing a sustainable means of storing renewable energy in high-density carbon-neutral fuels. The catalyst design features an exceptionally bulky N-heterocyclic carbene (NHC) ligand known as IPr** (3-Bis[2,6-bis[bis(4-tert-butylphenyl)methyl]-4-methylphenyl]-1H-imidazol-3-ium chloride), a coinage metal acting as a soft acid, and a hard base such as an alkoxide ion. Herein is reported a modified synthetic route of IPr**, along with its metalation with silver, and preliminary results of the addition of an alkoxide base. The ligand and its complex with silver are structurally characterized by nuclear magnetic resonance (NMR) spectroscopy. Further work is needed to complete the characterization of IPr**-supported HSAB mismatch complexes and investigate their potential to activate H2.
The Evangelical Ethic and the Spirit of Conspiracy Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2023-01-01
Creator: Jackson David Lakowsky Hansen
Access: Access restricted to the Bowdoin Community
Religious Negotiation and Identity Formation: Reading Material Religion in Oaxaca’s “Guelaguetza Oficial”
Date: 2023-01-01
Creator: Rene Sebastian Cisneros
Access: Open access
- The Oaxacan Guelaguetza Oficial is a folk-dance festival in the state of Oaxaca, Mexico which takes place on the last two Mondays of July each year. This state-sponsored celebration of Oaxacan identity is intertwined within histories of Indigenous religious belief and Catholic everyday practice. The Guelaguetza Oficial can be traced back to late 19thcentury celebrations venerating the Virgen del Carmen Alto. Oaxaqueños today predominantly practice an Indigenous-Catholic tradition whose rituals, festive scripts, pantheon of popular saints, and immanent understandings of heavenly power over earthly events can be traced back to negotiations between Indigenous forms of popular belief and institutionalized Catholic practice. Through historical and present-day religious tensions between existing modes of Indigenous religious belief and institutionalized Oaxacan Catholic practice, this thesis asserts that while Indigeneity often represented an obstacle to different structures of power in Mexican history, hegemonic institutions eventually came to accept the lasting presence of Indigenous identity and religious life to varying degrees within Mexican society and culture. This resulting reading of Guelaguetza demonstrates how religion is fundamentally implicated in the history of public festival and popular culture in Oaxaca. Furthermore, this thesis argues that Indigenous-Catholicism has not lost its prominence in public space in Oaxaca despite the reforms of post-1910 Oaxacan state and Mexican national politics and the effects of globalized neoliberal economies in the late 20th and early 21st centuries.
Design, Fabrication, and Evaluation of Surface Acoustic Wave Resonators on ST-X Quartz Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2023-01-01
Creator: Angela McKenzie
Access: Access restricted to the Bowdoin Community
Photosynthetic phenology of a boreal spruce forest observed at stand and needle scales This record is embargoed.
- Embargo End Date: 2025-05-19
Date: 2022-01-01
Creator: Jeremy A. Hoyne Grosvenor
Access: Embargoed
Exploiting Context in Linear Influence Games: Improved Algorithms for Model Selection and Performance Evaluation
Date: 2022-01-01
Creator: Daniel Little
Access: Open access
- In the recent past, extensive experimental works have been performed to predict joint voting outcomes in Congress based on a game-theoretic model of voting behavior known as Linear Influence Games. In this thesis, we improve the model selection and evaluation procedure of these past experiments. First, we implement two methods, Nested Cross-Validation with Tuning (Nested CVT) and Bootstrap Bias Corrected Cross-Validation (BBC-CV), to perform model selection and evaluation with less bias than previous methods. While Nested CVT is a commonly used method, it requires learning a large number of models; BBC-CV is a more recent method boasting less computational cost. Using Nested CVT and BBC-CV we perform not only model selection but also model evaluation, whereas the past work was focused on model selection alone. Second, previously models were hand picked based on performance measures gathered from CVT, but both Nested CVT and BBC-CV necessitate an automated model selection procedure. We implement such a procedure and compare its selections to what we otherwise would have hand picked. Additionally, we use sponsorship and cosponsorship data to improve the method for estimating unknown polarity values of bills. Previously, only subject code data was used. This estimation must be done when making voting outcome predictions for a new bill as well as measuring validation or testing errors. We compare and contrast several new methods for estimating unknown bill polarities.
An Investigation on Data Gaps in Scope 3 Emissions Accounting and Disclosure using 2010-2021 Carbon Disclosure Project (CDP) Questionnaire Responses This record is embargoed.
- Embargo End Date: 2027-05-17
Date: 2022-01-01
Creator: Samara Nassor
Access: Embargoed
Hypersensitization of Helicobacter pylori to Antibiotics Through Perturbation of Bacterial Glycan Armor Access to this record is restricted to members of the Bowdoin community. Log in here to view.
Date: 2022-01-01
Creator: William J. Rackear
Access: Access restricted to the Bowdoin Community
The evolutionary response of populations of the blue mussel (Mytilus edulis) populations to climate change
Date: 2014-08-01
Creator: Jenna Watling
Access: Open access
- Since early July, I’ve been working on three projects. I’ve been studying parrotfish speciation, dissecting green crabs, and collecting samples of muscle tissue from blue mussels. My primary occupation is the study of parrotfish speciation with Dr. Carlon. He has found evidence of speciation through hybridization, which is has not been commonly observed. During the 2013-2014 academic year, he and I extracted DNA from fin or scale samples from Pacific parrotfish. Throughout the year and during this summer, we have been amplifying specific genes—nuclear and mitochondrial—using a polymerase chain reaction, confirming the amplification via gel electrophoresis, and preparing the samples for Sanger sequencing, which is done by the Nevada Genomics Center. Once we receive the sequencing results electronically, I use the program Geneious to check the quality of the individual sequences and resolve ambiguous calls (e.g., whether a specific base pair is an arginine or a cytosine) and align the sequences so we can compare them base pair by base pair. By examining both nuclear and mitochondrial genes, which evolve at different rates, we can hypothesize about the way in which different species arise. Green crab (Carcinus maenas) dissection is an early step in Aidan Short’s analysis of their diet. I assist in collecting tissue samples. We collect muscle tissue from the crabs’ claws. These samples will allow Aiden to differentiate between the crabs’ food and the crabs themselves. Then their carapaces are cut open and their entire stomachs are collected. In the near future, Aidan will use next-generation sequencing to identify any species present in the crab stomachs and quantify the abundance of these species’ DNA. Sequencing the crabs’ stomach contents is more precise and more complete than the older method of hard part analysis. The green crabs’ diet is of interest because green crabs are an invasive species and have been implicated in loss of sea grass beds and decreasing soft shell clam populations. Collection of tissue from blue mussels (Mytilus edulis) and bay mussels (M. trossulus) is a preliminary step for Dr. Sarah Kingston’s investigation of the genetic basis of variation in shell calcification rate under environmental conditions possible due to ocean acidification. She collects mussels from various sites along the Maine coast, marks each with a color and number, and records their buoyant weight. The buoyant weight allows Dr. Kingston to determine the mass of the shells without having to kill the mussels. In the first round of experiments, Dr. Kingston determined which of three experimental schemes (involving the manipulation of food levels, temperature, and pH) resulted in the greatest variation of shell calcification after two weeks. The harshest scheme—no food, high temperature, and low pH—resulted in the greatest variation, and this scheme will be used in the experiment going forward. After the experimental period, the mussels are re-weighed and tissue samples are collected. I assist in tissue sample collection; we cut open the mussels and remove the foot and the adductor muscle. In the next round of experiments, I will further assist by participating in mussel collection, monitoring tank conditions during the experimental period, and labeling and weighing the specimens. The DNA libraries obtained from the tissue samples will be sent away for next generation sequencing, and Dr. Kingston will begin looking for genetic variation associated with calcification rates. Final Report, summer 2014 student-faculty research.
“I felt so untrustworthy of my ability to get pregnant”: Women’s Embodied Uncertainties and Decisions to Become Pregnant
Date: 2020-01-01
Creator: Theodora K. Hurley
Access: Open access
- This paper identifies “embodied uncertainties”—possibilities of aging and infertility lodged within the body—as informing women’s conceptualizations of their reproductive bodies and their decisions about and approaches to getting pregnant. Using data from semi-structured interviews with a small sample of highly educated, professional, white women who had given birth within 18 months prior, this paper argues that (bio)medicalized risk discourses and neoliberal logics of responsible choice-making lodge uncertainty and the possibility of failure within women’s reproductive bodies. As they attempt to reconcile childbearing with professional and financial constraints, women may identify their bodies as laden with embodied uncertainties and may subsequently adopt strategies for becoming pregnant that seek to mitigate those embodied uncertainties, such as by trying to conceive before feeling completely ready for a pregnancy. Ultimately, (bio)medicalization and neoliberalism have transformed reproductive aging and infertility into individualized concerns and foreclosed recognition of the institutional failures that create conflicts of aging, careers, and childbearing in women’s lives.