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Authigenic Iron Is A Significant Component Of Oceanic Labile Particulate Iron Inventories, Laura E. Sofen, Olga A. Antipova, Kristen N. Buck, Salvatore Caprara, Lauren Chacho, Rodney J. Johnson, Gabriella Kim, Peter Morton, Daniel C. Ohnemus, Sara Rauschenberg, Peter N. Sedwick, Alessandro Tagliabue, Benjamin S. Twining

OES Faculty Publications

Particulate phases transport trace metals (TM) and thereby exert a major control on TM distribution in the ocean. Particulate TMs can be classified by their origin as lithogenic (crustal material), biogenic (cellular), or authigenic (formed in situ), but distinguishing these fractions analytically in field samples is a challenge often addressed using operational definitions and assumptions. These different phases require accurate characterization because they have distinct roles in the biogeochemical iron cycle. Particles collected from the upper 2,000 m of the northwest subtropical Atlantic Ocean over four seasonal cruises throughout 2019 were digested with a chemical leach to operationally distinguish labile …

Phytoplankton Thermal Trait Parameterization Alters Community Structure And Biogeochemical Processes In A Modeled Ocean, Stephanie I. Anderson, Clara Fronda, Andrew D. Barton, Sophie Clayton, Tatiana A. Rynearson, Stephanie Dutkiewicz

OES Faculty Publications

Phytoplankton exhibit diverse physiological responses to temperature which influence their fitness in the environment and consequently alter their community structure. Here, we explored the sensitivity of phytoplankton community structure to thermal response parameterization in a modelled marine phytoplankton community. Using published empirical data, we evaluated the maximum thermal growth rates (μ_max) and temperature coefficients (Q₁₀; the rate at which growth scales with temperature) of six key Phytoplankton Functional Types (PFTs): coccolithophores, cyanobacteria, diatoms, diazotrophs, dinoflagellates, and green algae. Following three well-documented methods, PFTs were either assumed to have (1) the same μ_max and …

Carbonate Chemistry And Carbon Sequestation Driven By Inorganic Carbon Outwelling From Mangroves And Saltmarshes, Gloria M. S. Reithmaier, Alex Cabral, Anirban Akhand, Matthew J. Bogard, Alberto V. Borges, Steven Bouillon, David J. Burdige, Mitchell Call, Nengwang Chen, Xiaogang Chen, Luiz C. Cotovicz Jr., Meagan J. Eagle, Erik Kristensen, Kevin D. Kroeger, Zeyang Lu, Damien T. Maher, J. Lucas Pérez-Lloréns, Raghab Ray, Pierre Taillardat, Joseph J. Tamborski, Rob C. Upstill-Goddard, Faming Wang, Zhaohui Aleck Wang, Kai Xiao, Yvonne Y.Y. Yau, Isaac R. Santos

OES Faculty Publications

Mangroves and saltmarshes are biogeochemical hotspots storing carbon in sediments and in the ocean following lateral carbon export (outwelling). Coastal seawater pH is modified by both uptake of anthropogenic carbon dioxide and natural biogeochemical processes, e.g., wetland inputs. Here, we investigate how mangroves and saltmarshes influence coastal carbonate chemistry and quantify the contribution of alkalinity and dissolved inorganic carbon (DIC) outwelling to blue carbon budgets. Observations from 45 mangroves and 16 saltmarshes worldwide revealed that >70% of intertidal wetlands export more DIC than alkalinity, potentially decreasing the pH of coastal waters. Porewater-derived DIC outwelling (81 ± 47 mmol m^{−2 …}

Summer Research Fellowship Project Descriptions 2023, Clark Science Center's Summer Research Fellows Program

SURF Abstracts (Women in Science)

A summary of research done by Smith College’s 2023 Summer Research Fellowship (SURF) Program participants. Ever since its 1967 start, SURF has been a cornerstone of Smith’s science education. Supervised by faculty mentor-advisors drawn from the Clark Science Center and connected to its eighteen science, mathematics, and engineering departments and programs and associated centers and units. At summer’s end, SURF participants were asked to summarize their research experiences for this publication.

Synthesis And Kinetic Analysis Of Poly(N-Acryloylmorpholine) Brushes Via Surface Initiated Raft Polymerization, Esma Mutlutürk, Tuncer Çaykara

Turkish Journal of Chemistry

Polymer brushes are promising many applications as smart materials and biocompatible surfaces. Surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization is one of the most effective techniques for synthesis of well-defined polymer brushes. Herein, a biocompatible, uniform and stable poly(N-acryloylmorpholine)-silicon hybrid system was achieved using surface-initiated RAFT polymerization. Evidence of a well-controlled surface-initiated RAFT polymerization was confirmed by a linear increase of number average molecular weight (M$_{n}$) with overall monomer conversions. Water contact angle, ellipsometry, X-ray photoelectron spectroscopy and atomic force microscopy verified the presence of poly(N-acryloylmorpholine) (poly(NAM)) on silicon wafers. The grafting density (σ) and the average distance between grafting …

Investigation Of The Dehydration Of Ulexite Ore With Different Parameters And Modeling With Artificial Neural Network (Ann) Method, Mustafa Engi̇n Kocadaği̇stan

Turkish Journal of Chemistry

Study experiments were conducted considering the temperature, time, and sample weight parameters in order to model the dehydration by applying dehydration processes to ulexite ores. Data obtained from the dehydration processes of ulexite ore were compared with TG analyzes. It was observed as the result of the heat treatment that the fastest water removal was provided in the temperature range of 150-250 °C and it was very low in the range of 400-750 °C. In order to design the ANN method, 4 different models were proposed with the same parameters in the dehydration experiments and the network structure was determined. …

Enhanced Ionic Conductivity And Mechanical Strength In Nanocomposite Electrolytes With Nonlinear Polymer Architectures, Recep Bakar, Saeid Darvishi, Erkan Şenses

Turkish Journal of Chemistry

Solvent-free polymer-based electrolytes (SPEs) have gained significant attention to realize safer and flexible lithium-ion batteries. Among all polymers used for preparing SPEs electrolytes, poly(ethylene oxide), a biocompatible and biodegradable polymer, has been the most prevalent one mainly because of its high ionic conductivity in the molten state, the capability for the dissolution of a wide range of different lithium salts as well as its potential for the environmental health and safety. However, linear PEO is highly semicrystalline at room temperature and thus exhibits weak mechanical performance. Addition of nanoparticles enhances the mechanical strength and effectively decreases the crystallization of linear …

Synthesis And Characterization Of Pani And Pani/Nanometal Oxides, Photocatalytic And Adsorbent Applications, Bi̇lge Budak, Si̇bel Demi̇rel

Turkish Journal of Chemistry

In this study, polymeric nanocomposites of PANI and PANI/nanometal oxides (Fe2O3, NiO, SnO2, WO3, ZrO2) as photocatalysts were synthesized with a chemical polymerization method. Structural characterizations of synthesized polymeric nanocomposites were performed as follows: FT-IR, SEM, TEM and XRD, and TGA. The effect of pure nanometal oxides (Fe2O3, NiO, SnO2, WO3, ZrO2) and polymeric nanocomposites on the degradation of naproxen, the drug active ingredient, was studied under visible light (UV-A at 365 nm) and in the absence of light. In this study, photocatalytic and adsorbent efficiency of polymeric nanometal oxides were investigated. In order to determine the effect of pure …

Electrochemical Behavior, Antimicrobial Activities, And Effect Of Temperature On Micellization Of Imidazolium Monomeric Surfactants, Vinit Sharma, Tokuma Getahun, Manpreet Singh, Jaswinder Kaur, Nandita Thakur, Kamal Kishore

Turkish Journal of Chemistry

In the present study, we herein report the conductance behavior, effect of temperature, and chain-length of two environmentally friendly imidazolium cationic capric and stearic surfactants. The conductance behavior has been carried out in aqueous solvent (H2O) at four different temperatures such as 24 °C, 29 °C, 34 °C, and 39 °C. The normal micelles were formed in an aqueous solvent and critical micelle concentration (CMC) can be estimated through conductivity parameters. The expected dependency of the CMC on the alkyl chain length of the 3-(2-(decanoyloxy)ethyl)-1-methyl-1H-imidazol-3-ium-bromide and 3-(2-(octadecanoyloxy)ethyl)-1-methyl-1Himidazol- 3-ium-bromide was demonstrated. It was observed that the graphs of molar conduct activity …

Additive-Free Synthesis Of Poly(N-Vinyl Pyrrolidone) And Poly(N-Isopropylacrylamide) Nanogels With Controlled Sizes, Semi̇ha Duygu Süteki̇n, Feyza Kiraç, Olgun Güven

Turkish Journal of Chemistry

An easy method is proposed to prepare poly(vinyl pyrrolidone) (PVP) and poly(N-isopropylacrylamide) (PNiPAAm) nanogels with sizes less than 100 nm. The underlying principle is to prepare dilute polymer solutions in acetone/water mixtures where acetone acts to break tridimensional structure of water hence disrupting the H-bonds bridging polymer coils causing separation and shrinkage in their sizes. Irradiation of these solutions by gamma-rays directly leads to the formation of intramolecular crosslinks within the coils resulting with nanogels with sizes smaller than precursor coils. While the average size of nanogels of PVP irradiated in water only is 236 nm, they were reduced to …

A New Method In The Synthesis Of Conductive Polymers; Synthesis, Characterization, And Investigation Of Photocatalytic Properties Of Polyaniline, Muzaffer Can

Turkish Journal of Chemistry

As known, in the synthesis of conductive polyaniline polymer from aniline monomer, the polymerization medium must be acidic. In order to make the polymerization medium acidic, protonic acids such as HCl and H2SO4 are generally used. In this study, two acids have been used to make the polymerization medium acidic. One of them, as we know, is H2SO4 as a protonic acid. The other acid is the zinc ion, which is a Lewis acid. The metal ion has never been used for this purpose up to now. Two polyaniline polymers have been synthesized to prove that conductive polymers can also …

Synthesis Of Copper Nano/Microparticles Via Thermal Decomposition And Their Conversion To Copper Oxide Film, Çağdaş Allahverdi̇

Turkish Journal of Chemistry

Copper nano/microparticles were synthesized in octadecene at 290 °C by thermal decomposition method. Copper acetate monohydrate, stearic acid, and 1-octadecanol were used as copper precursor, capping and mild reducing agents, respectively, at the synthesis. Borosilicate glass substrates submerged into the reaction solution during the synthesis were coated by copper nano/ microparticles. Thermal decomposition and coating techniques were combined in this study. Copper nano/microparticles were thoroughly characterised via X-ray powder diffraction, X-ray photoelectron, Raman, and attenuated total reflectance-Fourier transform infrared spectroscopies, and scanning and transmission electron microscopies. The average minimum Feret?s diameter of these synthesized copper particles was measured as ~87 …

Theoretical Investigation Of Steric Effects On The S1 Potential Energy Surface Of O-Carborane-Anthracene Derivatives, Fahri̇ Alkan

Turkish Journal of Chemistry

TDDFT scan calculations were performed for s-carborane-anthracene derivatives (o-CB-X-Ant where X=-H, -CH3, -C2H5 and tert-butyl or -tBu) in order to understand the interplay between the steric effects, S1 potential energy surface (PES) and photophysical properties. The results show that all systems exhibit three local minima on the S1 PES, which correspond to the emissive LE and TICT state, along with the nonemissive CT state respectively. In the case of the unsubstituted system (o-CB-H-Ant), and -CH3 and -C2H5 substituted cases, S1 PES is predicted to be quite flat for certain conformations indicating that it is possible for these systems to reach …

Effect Of Carbon Fiber Reinforcement On Dimensional Variations Of 3d Printed Polyamide-6 Composites: A Simulation Study, Ans Al Rashid, Hamid Ikram, Muammer Koç

Turkish Journal of Chemistry

Due to material design and fabrication flexibility, additive manufacturing (AM) or 3D printing (3DP) processes and polymer composites have paved their way into several industrial sectors. The quality of 3D printed polymer composites is highly dependent on the reinforcement content of polymers and 3DP process parameters. Several experimental studies are performed to optimize the reinforcement contents and process parameters; however, exploring the numerical modeling and simulation techniques is vital to lower the research and development costs. In the study, the numerical simulations for the 3DP process were performed using Digimat® software for carbon fiber-reinforced polyamide-6 (PA6) composites fabricated via the …

In-Person And Remote Employees And Information Security Policy Compliance, Joyce Yin Mui

All-Inclusive List of Electronic Theses and Dissertations

Many workers have changed their working status from in-person to remote, in the past several years, with a large increase in the number of employees working remotely during and after the COVID-19 pandemic. In parallel, the increasing costs of data breaches and number of security incidents continue to be a concern to organizations seeking to protect their organization, systems, and data. This studys research questions were formed using a theoretical framework of the Theory of Planned Behavior (TPB) to discover influences on employee behavior and the Social Bonds Theory (SBT) to address strength of relationships and impact to compliance. This …

Graph Neural Networks For Ethereum Fraud Detection, Charity Mwanza

Theses

Detecting fraudulent transactions on the Ethereum network can help cryptocurrency companies that operate on the Ethereum platform protect their users from exposure to fraudsters. The most common fraudulent activities in the cryptocurrency network include phishing and smart Ponzi schemes. Since cryptocurrency technology is still young, most investors lack knowledge of how the smart contacts used in the Ethereum platform operate; hence, they cannot evaluate the risks they are exposed to when carrying out cryptocurrency transactions. The key role that this paper looks at is the application of graph neural networks in the extraction of features of users in the Ethereum …

An Airborne Multi-Band Microwave Analysis Of Precipitation Within Two Winter Cyclones, Amanda Richter

Theses

When precipitation becomes organized into bands, it can result in great differences in precipitation accumulation across a geographic area with disruptions to daily life and economic activity. While investigations have been conducted to discern microphysical details within banded precipitation environments, such details remain very uncertain across and within storms. It is the goal of the Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) to gather data using satellite-simulating and in situ aircraft to study banded storms. This study focuses on the Conical-Scanning Millimeter-wave Imaging Radiometer (CoSMIR), The Advanced Microwave Precipitation Radiometer (AMPR), and The High Altitude Imaging Wind …

Software Defined Radio (Sdr) With Applications In Radar Systems, Makenzie Fogle

Theses

This research tests the validity of using a cost-effective SDR to implement a pulsed radar system. This cost-effective system would enable students to build and utilize this system to learn more about radar engineering and possibly pursue a career in radar engineering. Also, this system would enable a university to build a teaching laboratory for university students learning Radar principles. An adalm-pluto SDR is used along with the MIT “cantennas”. The software used to implement the system is discussed. The results from both indoor and outdoor tests are shown and validated. This research could have applications in education, industry, and …

Bayesian Model Calibration Of A Mechanical Finite Element Model Of An Lr61 Alkaline Battery, William O'Donoghue

Theses

The growing use of batteries in vehicular applications and its associated risk of crashes that develop large deformations has raised the salience of how mechanical loads can lead to battery failure and cascade to battery pack fires. Batteries are complicated devices containing many materials with complex behaviors, making calibration of mechanical simulations an involved process. There are many techniques in the inverse problem field which could complement existing model tuning procedures through reducing the required number of experimental tests by extracting more information out of each data set and identifying which observations can most improve the model parameters at the …

Assessment Of Public Transit And Access To Essential Services And Facilities In Huntsville, Alabama, Sachin Shivashankar

Theses

This study aims to investigate the accessibility of public transit within the City of Huntsville, Alabama, in Madison County. Accessibility, in this context, refers to the distance between the residents in a certain census tract to essential amenities such as hospitals, schools, parks, workplaces, and other necessary services using public transportation. Data were obtained from the US Census Bureau and the City of Huntsville's Data Depot, focusing on aspects such as population socio-demographic attributes, and the distribution of essential amenities within the Huntsville city. Utilizing a range of Geographic Information System (GIS) methodologies and tools, including proximity analysis, random forest …

Evaluating The Trade-Offs Of Using Additive Manufacturing For Liquid Rocket Engines, Joshua Buettner

Theses

Liquid rocket engines (LRE) are among the most expensive components of any launch vehicle. While additive manufacturing (AM) shows promise in alleviating some of the costs of LREs, the use of AM could introduce new failure modes which would increase time spent in Test-Fail-Fix. This thesis demonstrates a methodology for understanding the trade-offs of using additive manufacturing for LREs to inform decision making. A decision matrix was used to choose the ideal AM process, and a quantitative model was applied to capture one of the trade-offs of using AM, that being increased surface roughness on LRE performance. A candidate component …

Solar Flare Forecasting : A Study Of Flare Coincidence, Christian W. Hall

Theses

Data mining techniques that can support the forecasting of solar flares are explored. The main focus is to investigate the effects of flare coincidence on the evaluation of forecasts. Coincident flares are solar flares in a region of the Sun in which another flare has occurred recently, whereas other flares are denoted as non-coincident flares. Dimensionality reduction and classification are two of the types of techniques examined, where binary classification is used to issue yes/no forecasts of major solar flares. Five algorithms are considered as binary classifiers: k-nearest neighbors (k-NN), logistic regression (LR), support vector machines (SVM), random forest classifiers …

An Investigation Of Mission Designs To The Outer Solar System Supported By Centrifugal Nuclear Thermal Propulsion, William Ziehm

Theses

Centrifugal nuclear thermal propulsion (CNTP) has potential for supporting scientific missions to the outer solar system, shown by investigation of mission and vehicle architectures to the outer planets and Kuiper belt. The patched conic method provided initial guesses for numerical simulation and relationships between parameters of interest for trade studies, recommending engine performance parameters for missions supported by CNTP. Results of the patched conic model were validated by comparison to numerical results, which were within the expected variance for transit time with identical propellant margins based on literature. The trade studies gave a range of performance required to close rendezvous …

Extended, Exactly Solvable Chaotic Oscillator, Micah Tseng

Theses

Although the study of chaotic systems is theoretically mature for abounding examples, few are readily applicable to engineering problems. One notable barrier is the lack of analytic solution to guide or validate an engineered intention. In this thesis, a small set of chaotic systems known for their analytic solutions is expanded. Specifically, a known solvable second order solvable chaotic oscillator with a simple matched filter is extended such that the data rate is decoupled from the natural oscillation frequency of the oscillator. This development allows for high frequency applications without the need for high frequency switching. An extended, exact analytic …

Analysis Of Interconnected Subreddits On The Reddit Social Network, Lance Lindner

Theses

This thesis analyzes the Reddit social network to identify two aspects of interactions on that platform: (1) implicit leader-follower relationships, which are obtained by mining patterns of user interactions on the network and (2) highly “interconnected” subreddits which are obtained by scoring each subreddit using a “interconnectedness” value derived from the interaction patterns of users across subreddits. The data were obtained from Reddit in 2022 using a custom-built scrapper. This work analyzed 125,000 subreddits. The results show that the most highly connected subreddits on the Reddit network are ones that discuss content considered to be “not suitable for work” (NSFW). …

Design And Fabrication Of A High-Performance Heat Exchanger Using An Optimized Three-Dimensional Surface Structure Through Additive Manufacturing, Seth T. Waters

College of Graduate Studies: Theses & Dissertations

A heat exchanger is a device used to transfer thermal energy between two intertwining fluid pathways. In this study, the design of a novel heat exchanger is proposed using functional gradient double gyroid structure. The complex internal geometries of the gyroid structure significantly increases the surface area to volume ratio, and potentially could expressively improve efficiency of the heat transfer. The proposed idea provides a new approach for the design of a high-efficiency heat exchanger. In order to fabricate the complex structured heat exchanger system additive manufacturing is adapted instead of traditionally subtractive manufacturing techniques or casting. The prototypes of …

Educator Perceptions Of Self-Efficacy And Preparedness To Work In High Poverty Schools, Kristen Carroll

College of Graduate Studies: Theses & Dissertations

ABSTRACT

The school leader and teacher have the greatest impact on student success. The level of self-efficacy and level of preparedness is of the utmost importance for educators and students alike. This study investigated the perceptions of educators in the belief of whether they were adequately prepared to teach in a high poverty school. The participants, educators from four school districts, completed a survey based on their perceptions of their own level of self-efficacy and preparedness to work in high poverty schools. The results of this study are aimed at impacting educator preparedness to better understand how to best support …

Effectives Of Different Shaped Dimples On A Naca Airfoil, Mostafa M. A Khater, Venkatesan Govindaraj

Babylonian Journal of Mechanical Engineering

This research addresses changes in the aerodynamic properties of the airfoil caused by modifying the surface in the form of dimples. The first surface changes mentioned here the wing model has dimples that face inside and outward. Airfoil models that have been modified to illustrate variation lifting and dragging at varying angles of attack (AOA). Surface adjustments are made here by taking into account the various types and forms of dimples. When an airfoil reaches a certain angle of attack, dimples serve to reduce pressure drag because wake production begins owing to boundary layer separation. Dimples on an aeroplane wing …

Achieving High Map-Coverage Through Pattern Constraint Reduction, Yingquan Zhao, Zan Wang, Shuang Liu, Jun Sun, Junjie Chen, Xiang Chen

Research Collection School Of Computing and Information Systems

Testing multi-threaded programs is challenging due to the enormous space of thread interleavings. Recently, a code coverage criterion for multi-threaded programs called MAP-coverage has been proposed and shown to be effective for testing concurrent programs. Existing approaches for achieving high MAP-coverage are based on random testing with simple heuristics, which is ineffective in systematically triggering rare thread interleavings. In this study, we propose a novel approach called pattern constraint reduction (PCR), which employs optimized constraint solving to generate thread interleavings for high MAP-coverage. The idea is to iteratively encode and solve path conditions to generate thread interleavings which are guaranteed …

Demonstrating Multi-Modal Human Instruction Comprehension With Ar Smart Glass, Mudiyanselage Dulanga Kaveesha Weerakoon, Vigneshwaran Subbaraju, Tuan Tran, Archan Misra

Research Collection School Of Computing and Information Systems

We present a multi-modal human instruction comprehension prototype for object acquisition tasks that involve verbal, visual and pointing gesture cues. Our prototype includes an AR smart-glass for issuing the instructions and a Jetson TX2 pervasive device for executing comprehension algorithms. With this setup, we enable on-device, computationally efficient object acquisition task comprehension with an average latency in the range of 150-330msec.