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Content And Consequences: Impact Of Representation In Stem Higher Education Instructional Content On Marginalized Students, Nichole Ventura

Doctorate in Education

This qualitative study examined representation of historically marginalized students in STEM instructional content at the higher education level and its impact on their learning experiences. Despite growing diversity initiatives in STEM enrollment, curricular materials often fail to reflect the identities of underrepresented students. Using critical theory and interpretivist approaches, this research investigated how representation—or its absence—shapes students' sense of belonging, academic identity formation, and persistence. Through semi-structured interviews with undergraduate students from historically marginalized backgrounds, and purposeful sampling, this study captured the lived experiences of students engaging with STEM instructional materials. Interview protocols explored how students perceive their representation in …

Evaluation Of Graphite And Activated Carbon As Suitable Water Purification Media For In-Situ Resource Utilisation (Isru) On Mars, Ciaran Archenoul

The Plymouth Student Scientist

Eventual human missions to the red planet will require large-scale in-situ resource utilisation to meet their objectives. Perhaps the most critical element for developing a sustainable architecture is propellant production from the products of water electrolysis and atmospheric carbon dioxide. The purpose of this study was to assess how graphitic materials may be used as porous filters to remove solvated ions from Martian water prior to electrolysis, reducing the overall complexity of ISRU systems. The two materials under study were PG25 graphite and activated carbon powder.

A comprehensive three-technique characterisation of both materials was performed, using helium pycnometry, N_{2 …}

Process Optimization And Cost Reduction For Cellulose Nanocrystals For Metal Removal From Rendered Fat, Sheikh Abdur Rehman

All Theses

Cellulose nanocrystals (CNCs) coupled with polymers featuring a high density of amine functional groups, such as polyethylenimine (PEI), exhibit significant metal-capturing capabilities. Rendered animal fat has applications in a vast number of industries, with the potential to be used as a feedstock for the biodiesel/renewable diesel industries. Nevertheless, rendered fat samples occasionally contain concentrations of metals/inorganic contaminants above the suitable threshold for use in this application. Thus, a cost-effective solution to remove light metal/inorganic contaminants from rendered fat samples is desirable.

To address this problem, a cellulose nanocrystal coupled with polyethylenimine, i.e., CNC-f-PEI, was developed by previous …

Exploring Halogen Bonding Interactions In Cocrystals And Deep Eutectic Solvents, Madhushi Bandara

All Dissertations

Halogen bonding is a noncovalent intermolecular interaction analogous to hydrogen bonding that occurs between an electrophile and a nucleophile. This is often observed in compounds containing heavy halogens such as iodine and bromine. When these halogens are covalently bonded to another atom or molecule, preferably to an electron-withdrawing moiety, an electrophilic region called a sigma hole is created on the halogen atom on the extension of the covalent bond.

The first study of this dissertation presents a comprehensive characterization of eight newly synthesized triiodide salts using single-crystal X-ray diffraction, powder X-ray diffraction, thermal analysis (DSC and TGA), and Raman spectroscopy. …

Molecular Design And Engineering Of Luminophores For Aggregation Induced Electrogenerated Chemiluminescence, Jesy Alka Motchaalangaram

Dissertations

Most conventional luminophores produce intense emissions in solutions but suffer from weak emissions or quenching when aggregated in poor solvents due to intermolecular interactions, such as π-π stacking. This phenomenon is known as aggregation caused by quenching (ACQ), limits their applications in their solid state. In contrast, aggregation induced emission (AIE) is a phenomenon in which luminophores are weak- or non-emissive in solution but emit intensively in their aggregated or solid states. AIE has enabled significant advancements in various real-world applications and has inspired new areas of research. The combination of AIE with electrogenerated chemiluminescence (ECL) has resulted in a …

Tracing The Journey Of Dissolved Organic Matter: From Leaf Litter Photodegradation To Microbial Processing In Tropical Streams, Samantha Nicole Sullivan

Chemistry & Biochemistry Theses & Dissertations

Dissolved organic matter (DOM) is a major reservoir of organic carbon in aquatic ecosystems and plays a central role in global carbon cycling through its transformation and remineralization to carbon dioxide (CO₂). As DOM moves from terrestrial environments into streams and rivers, its chemical composition is altered by a combination of microbial and photochemical oxidation processes that regulate both its reactivity and its persistence during transport. However, the molecular mechanisms governing these oxidative transitions, particularly in tropical ecosystems characterized by strong hydrologic seasonality and substantial inputs of plant-derived material, remain insufficiently resolved. This dissertation integrates ultrahigh-resolution mass spectrometry, optical characterization, …

Optimization In The Synthesis Of Dual Ionic-Liquid-Functionalized Cellulosic Materials, Megan L. Franke

Honors College Theses

There is a growing urgency to develop sustainable alternatives to petroleum-based materials as concerns about environmental impact and resource depletion intensify. Among renewable biopolymers, cellulose stands out as one of the most abundant and versatile organic compounds on Earth. As the structural backbone of plant cell walls, it provides rigidity and mechanical strength, while its abundance, biodegradability, and tunable chemistry make it an attractive candidate for sustainable materials. Beyond its traditional uses in textiles, paper, and food additives, cellulose has been increasingly investigated in polymer chemistry for advanced

applications. The present study aims to optimize synthetic routes to dual ionic …

Automation And Upgrading Of Custom Cold Wall Uhv-Cvd Reactor For Group Iv Material Development, Alexander Golden

Graduate Theses and Dissertations

Group IV alloys have shown promising results for infrared optoelectronic applications where III-V materials are currently dominant. The III-V material system has vacancies that Group IV materials can fill, most importantly complementary metal oxide semiconductor (CMOS) process compatibility making quality devices much cheaper and widely available compared to the current state of the art. Silicon, being an indirect band gap Group IV material, has poor performance in optoelectronic applications but is the dominant material for most of the electronic industry. However, when silicon is alloyed or substituted with other group IV materials, these optoelectronic properties can be enhanced and, in …

Mechanistic Analysis Of Rare Earth Element Extraction From Coal Byproducts Using Supercritical Fluid Process: Solubility Studies Of Supercritical Carbon Dioxide With Tbp: Hno3 Complex, Zakiya Konda Nurudeen

Engineering

This thesis introduced the essence of REE application in the modern world, the primary and secondary sources of REEs. It revised the fundamentals of supercritical carbon dioxide (SC- CO2), its application in REE extraction as green technology, the complex formation of tributyl phosphate (TBP)- nitric acid (HNO3), and temperature-pressure effects in REE extraction. The methodology systematically examined the thermodynamic solubility of CO2 in TBP-nitric acid (HNO3) complexes at three molar ratios (2:1, 1:1, and 1:2), temperatures between 40-60 degrees Celsius, and at a maximum pressure of 12 MPa, respectively. Preliminary extraction experimental runs were conducted to validate solubility studies. Data …

Development Of A Digestion Procedure Using Fe2+ Ions For Electrochemical Detection Of Mno2 Particles In Drinking Water, Kayla Elliott, Sarah Jane Payne, Zhe She

Journal of Electrochemistry

Developing methods for detection contaminants in drinking water is essential to ensuring that safe and acceptable quality drinking water is delivered to consumers. While manganese (Mn) was previously known only as a mere aesthetic issue, recent epidemiological data has shown to have negative neurological effects on humans, especially on children, prompting new health-based guidelines by Health Canada and the World Health Organization. In drinking water, Mn exists predominantly as Mn(II) and Mn(IV), and is regulated based on total Mn levels. Interestingly, measurement of Mn particulate using electroanalytical methods has not yet been reported in the literature. Herein, a digestion procedure …

Regulating Lithium Metal Nucleation And Growth For Dendrite Suppression: From Liquid-Electrolyte To Solid-State Batteries, Ao Du, Juan Zhang, Pan Xu, Ya-Jie Li, Kang-Yu Yi, Zhen-Zhen Shen, Hui-Lin Ge, Guang-Wen Zhang, Chao-Hui Zhang, Yu-Hao Wang, Chen-Zi Zhao, Meng-Yang Xu, Yu-Lin Jie, Rui Wen, Shu-Hong Jiao, Si-Qi Shi, Qiang Zhang, Chun-Peng Yang, Yu-Guo Guo

Journal of Electrochemistry

Lithium metal anodes, with a theoretical capacity of up to 3860 mAh·g⁻¹, are regarded as the cornerstone for developing next-generation high-energy-density batteries. However, several key challenges hinder their practical applications, including dendrite formation, unstable solid electrolyte interphase (SEI), side reactions with electrolytes, and associated safety risks. This review systematically explores the mechanisms of lithium nucleation, growth, and stripping in both liquid and solid-state battery systems, analyzing critical theoretical concepts like heterogeneous nucleation thermodynamics, surface diffusion kinetics, space charge effects, and SEI-induced nucleation, which are crucial for understanding the genesis of dendrite growth. Additionally, the review discusses the electrochemical-mechanical …

Biocompatible And Antibacterial Pcl-Tio2@Ag/Γ-Cd Mof Nanocomposite Coating For Corrosion Resistance Of Magnesium Alloy In Simulated Body Fluid, Sara Dehghan-Chenar, Hamid R. Zare, Zahra Mohammadpour, Maryam Sadat Mirbagheri-Firoozabad

Journal of Electrochemistry

Magnesium alloys are promising candidates for bio-implant applications due to their biodegradability and biocompatibility. However, their rapid corrosion remains a critical limitation. This study presents the development of a multifunctional nanocomposite coating designed to enhance the corrosion resistance and antibacterial properties of magnesium alloy implants. The coating comprised γ-cyclodextrin metal-organic frameworks (γ-CD MOFs) decorated with TiO₂@Ag core-shell nanoparticles, embedded in a polycaprolactone (PCL) matrix. Immersion tests in a simulated body fluid (SBF) revealed an initially higher corrosion rate for the PCL-TiO₂@Ag/γ-CD MOF coating compared to the coating without TiO₂@Ag nanoparticles; however, it demonstrated significant …

Novel Eco-Friendly Synthesis Of Coo Nps: Evaluation Of Their Diode Laser-Enhanced Inhibitory Activity Through Combined In Silico And In Vitro Approaches., Arshad Mahdi Hamad, Sahar Naji Rashid

Karbala International Journal of Modern Science

In our study, for the first time worldwide, to the best of our knowledge, cobalt oxide nanoparticles (CoO NPs) were synthesized using naringin (Nar) extracted from citrus peels. The properties of the prepared Nar-CoO NPs were studied using field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), ultraviolet-visible (UV-Vis), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. All the test results demonstrated the efficiency and success of the nanofabrication process. The solution was then exposed to three types of diode lasers: red (650 nm), green (532 nm), and blue (405 nm). The purpose of this study was …

Synergistic Doping And Coating Strategy For Boosting Na0.7mno2 Cathode Performance In Sodium-Ion Batteries, Ahmad Helaley, Han Yu, Manashi Nath, Xinhua Liang

Chemistry Faculty Research & Creative Works

Advancing sodium-ion battery (SIB) technology requires novel approaches to optimize cathode materials for improved electrochemical performance. In this study, we employ atomic layer deposition (ALD) to precisely modify the surface of P2-type Na_0.7MnO₂ cathodes with different coating materials including ZnO, NiO, and Al₂O₃, followed by post-annealing at 750°C for 10 hours. The strategic combination of ALD and thermal treatment can achieve thin film coating on particle surface and promote element doping into the near-surface lattice, as confirmed by electron energy loss spectroscopy (EELS) analysis. The incorporation of Zn, Al, and Ni results in …

Synthesis And Characterization Of Eco-Engineered Hollow Fe2o3/Carbon Nanocomposite Spheres: Evaluating Structural, Optical, Antibacterial, And Lead Adsorption Properties, Islam Gomaa, Nikita Yushin, Mekki Bayachou, Vojislav Stani´, Inga Zinicovscaia

Chemistry Faculty Publications

This work presents a facile mechano-thermal route for the synthesis of carbon-decorated, hollow, mesoporous alpha-Fe2O3 microspheres. Comprehensive characterization (XRD, XPS, FT-IR, SEM/EDX, TGA, zeta-potential) confirmed the formation of phase-pure hematite with nanoscale crystallites (similar to 19 nm), substantial residual surface carbon (similar to 40 wt%) consistent with Fe-O-C linkages, and a positive surface charge (+15.9 mV). The hierarchical hollow/mesoporous architecture enables fast ion transport and provides extensive interior binding sites, resulting in rapid Pb(II) uptake that reaches 92% removal in approximate to 15 min at pH 5.0. The adsorption follows a Langmuir isotherm (q(max) approximate to 70.6 mg/g) and pseudo-second-order …

On Heat Engines Having Efficiencies That Degrade With Every Cycle That Are Nonetheless Reversible: The Wonders Of Hilbert Curves In The Pressure-Volume Plane, Daniel Graham

Chemistry: Faculty Publications and Other Works

Heat engines are cornerstones in classical thermodynamics, not to mention fixtures of everyday life. As everyone knows, real heat engines are rife with sources of irreversibility, and, in turn, have efficiencies that degrade over time. Here we chart a classical heat engine whose efficiency degrades with every cycle, but maintains perfect reversibility nonetheless. There are no paradoxes in play due to the inviolability of the thermodynamic laws. Rather the engine operates transparently according to Hilbert curves that fill the pressure-volume plane. The assembly of the curves is iterative and digital whereby no information is lost over every cycle.

Analysis Of An Effective Training Curriculum: Solutions Toincrease Participants' Interest In Training Teachingmaterials, Maulidya Husnul Khatimah, Yoto Yoto

Jurnal Pendidikan Sains

This research is important because it analyzes the curriculum as a primary tool for generating and maintaining participant interest. Curricula that are irrelevant, monotonous, or misaligned with participant needs are often the main causes of low motivation and participation. Furthermore, this research encourages the exploration and implementation of more innovative teaching methods and materials in training curricula. External pressure in the form of demands or instructions, rather than internal motivation, drives most training activities. This can reduce engagement and learning effectiveness. To overcome this, training institutions need to design programs that are relevant, flexible, and able to encourage participants' intrinsic …

Augmented Reality-Assisted E-Module On Temperature Andheat Content (Emarks), Tetri Sabrina, Ika Mustika Sari, Dedi Sasmita

Jurnal Pendidikan Sains

Temperature and heat content (calor) material in physics often involves concepts and phenomena that are difficult to observe directly or are abstract (such as energy transfer, particle movement, and changes in state). EMARKS (AR-based E-modules) are important because Augmented Reality (AR) allows the visualization of these abstract concepts in the form of interactive 3D models in the user's real environment. This helps students understand the concepts more concretely and easily. The development of E-modules is an innovation in learning media that is relevant to the demands of the digital era and the needs of modern students. The use of advanced …

The Effect Of Guided Inquiry Model With Deep Learningapproach On Student’S Hots In Elements, Compounds,And Mixtures At Junior High School, Friska Pakpahana, Retno Dwi Suyanti

Jurnal Pendidikan Sains

The current education curriculum places a strong emphasis on developing HOTS skills (such as analyzing, evaluating, and creating) to prepare students for the challenges of the 21st century. School learning often focuses on lower-level cognitive domains (memorizing and understanding). This research seeks to address this gap by offering a potentially effective learning model. The guided inquiry model positions students as active participants in learning, encouraging them to investigate, discover, and formulate concepts independently with teacher guidance. This strongly supports the development of critical thinking and problem-solving skills. Therefore, this study aims to analyze the effect of the guided inquiry model …

Guided Inquiry Learning Assisted By Crossword Puzzlemedia: Student Scientific Literacy And Critical Thinkingability For Middle School, Agis Putri Niswa, Mariati Purnama Simanjuntak, Ramlan Silaban, Fauziyah Harahap, Ridwan Abdullah Sani

Jurnal Pendidikan Sains

Scientific literacy and critical thinking skills are two fundamental competencies that students need in the 21st century. Scientific literacy is essential for students to understand and use scientific knowledge to make informed decisions, while critical thinking trains students to analyze information, evaluate arguments, and solve problems logically. Therefore, the intent of this study was to determine the effect of the guided inquiry learning model assisted by crossword puzzle media on students’ scientific literacy and critical thinking skills. The type of research used was quasi-experimental with a two-group pretest-posttest design. The sample consisted of two classes: class VII-8 as the control …

Elucidating The Effects Of Water Activity On The Hydration Kinetics And Thermodynamics Of Ye’Elimite–Calcium Sulfate Hydrate Systems, Godwin I. Ogbuehi, Rupack R. Halder, Aditya Kumar, Gaurav Sant, Monday U. Okoronkwo

Materials Science and Engineering Faculty Research & Creative Works

Relative humidity and water activity (aH) reductions have been known to suppress the hydration of anhydrous cement clinker phases. However, the relationship between ye'elimite (C4A3$) hydration kinetics and water activity remain unclear. This study employs experimental and thermodynamic modeling approaches to investigate the influence of water activity on ye'elimite hydration in the "C4A3$ + water", and "C4A3$ + gypsum + water" systems. Experimental findings indicate that as water activity decreases, C4A3$ hydration diminishes until the reaction is brought to a halt at a threshold aH. The critical aHand corresponding solubility constant of C4A3$ (KC4A3S¯) estimated from thermodynamic analysis are 0.46 …

Importance Of S-Doped Porous Carbon Acidity And Visible Light Photoactivity For Its Antibacterial Activity, Danela Sadikaj, Abanob Fekri, Isabelle Bautista, Nafisatu Davis, Tasnim Agha Alkla, Muhammad Moueed Haider Mirza, Jiaying Wang, Phillip Stallworth, Natalie Hudson-Smith, Teresa J. Bandosz, Xiaojun Yu, Steven Greenbaum, Wanlu Li

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

Bactericidal activity of sulfur-doped carbon has been investigated against a common Gram-negative bacterium, Escherichia coli K-12 (E. coli), in aqueous solution. Under dark conditions, 1 h contact of carbon with bacteria resulted in a 3–4 log decrease from the initial concentration of 7 log. When exposed to visible light, a 6–7 log decrease in E. coli was observed. The bactericidal activity under dark conditions was linked to the effects of functional groups, particularly sulfonic groups, which released protons that contributed to bacterial death. Even though under visible light no reactive oxygen species (ROS) were detected in electron paramagnetic …

Electrochemical Breath Sensors In Medical Diagnostics: Emerging Trends And Future Directions, Natalie E. Strom, Courtney J. Weber, Olja Simoska

Faculty Publications

With the rising prevalence of metabolic diseases, infections, and mental health disorders, there is a growing demand for noninvasive diagnostic tools that enable early detection and continuous health monitoring. In this context, exhaled breath biomarkers provide insight into physiological and pathological processes. Electrochemical breath sensors (EBSs) have emerged as a promising platform for rapid, real-time, and cost-effective disease tracking via the detection of volatile breath biomarkers, such as NH₃, NO, and CO₂. Recent advancements in electrode materials, biological recognition elements, and sensor architectures—spanning nanomaterials, enzymes, aptamers, and molecularly imprinted polymers—have enhanced the analytical performance of EBSs. …

Electrochemical Breath Sensors In Medical Diagnostics: Emerging Trends And Future Directions, Natalie E. Strom, Courtney J. Weber, Olja Simoska

Faculty Publications

With the rising prevalence of metabolic diseases, infections, and mental health disorders, there is a growing demand for noninvasive diagnostic tools that enable early detection and continuous health monitoring. In this context, exhaled breath biomarkers provide insight into physiological and pathological processes. Electrochemical breath sensors (EBSs) have emerged as a promising platform for rapid, real-time, and cost-effective disease tracking via the detection of volatile breath biomarkers, such as NH₃, NO, and CO₂. Recent advancements in electrode materials, biological recognition elements, and sensor architectures—spanning nanomaterials, enzymes, aptamers, and molecularly imprinted polymers—have enhanced the analytical performance of EBSs. …

Neural Network Ensemble For Computing Cross Sections Of Rotational Transitions In H2O + H2O Collisions, Bikramaditya Mandal, Dmitri Babikov, Phillip C. Stancil, Robert C. Forrey, Roman V. Krems, Naduvalath Balakrishnan

Chemistry Faculty Research and Publications

Water (H₂O) is one of the most abundant molecules in the universe and is found in a wide variety of astrophysical environments. Rotational transitions in H₂O + H₂O collisions are important for modeling environments rich in water molecules but they are computationally intractable using quantum mechanical methods. Here, we present a machine learning (ML) tool using an ensemble of neural networks (NNs) to predict cross sections to construct a database of rate coefficients for rotationally inelastic transitions in collisions of complex molecules such as water. The proposed methodology utilizes data computed with a mixed …

Cobalt Layered Double Hydroxide As Advanced Electrode Materials For Supercapacitors And Electrocatalysis, Wafa Sultan Alaryani

Theses

Due to the high demand for sustainable energy storage options and efficient energy conversion devices, extensive research has been conducted on various electrode materials. This thesis is concerned with the fabrication of electrode material mainly using cobalt-based material, particularly cobalt layered double hydroxides (Co-LDH) with the combination of nitrogen-doped carbon nanotubes (N-CNTs) to be used in supercapacitors and oxygen evolution reactions (OERs) applications. The main objective is to enhance the electrochemical performance of supercapacitors and to develop a novel electrode material for a more stable and efficient OER in alkaline medium.

The methodology involved a one-step hydrothermal procedure to synthesize …

Substituted Piperidines As (Alpha4)3(Beta2)2 Nicotinic Acetylcholine Receptor Positive Allosteric Modulators: In Vitro Pharmacology, Nataly Sanchez, Josue Gaona, Wilder Felix, Nathalia Menegasso, Brisa Cea, Ganesh Thakur, Ayman K. Hamouda

School of Medicine Student Publications and Presentations

Nicotinic acetylcholine receptors (nAChRs) play a crucial role in the pathogenesis of neurodegenerative diseases such as Parkinsonʼs disease (PD). In PD, degeneration of dopaminergic and cholinergic neurons impairs neurotransmitter release, leading to cognitive and motor dysfunction. Current treatments provide only symptomatic relief, highlighting the need for novel therapeutic strategies. The (α4)₃(β2)₂ subtype of nAChRs is expressed on affected neurons, making it a promising druggable target for enhancing neurotransmitter release and providing neuroprotection. To explore the therapeutic potential of positive allosteric modulators (PAMs) of (α4)₃(β2)₂ nAChRs, we evaluated chemical derivatives of CMPI [3-(2-chlorophenyl)-5-(5-methyl-1-(piperidin-4-yl)-1H-pyrazol-4-yl)isoxazole]. We used two-electrode voltage-clamp recordings from Xenopus laevis …

Defect-Driven Degradation Of Mxenes In Aqueous Environments And Mitigation Strategies: Insights From First-Principles, Ana Maria Stratulat, Valentina Nesterova, Vladislav Korostelev, Majid Beidaghi, Vadym Mochalin, Konstantin Klyukin

Chemistry Faculty Research & Creative Works

MXenes have attracted considerable attention due to their tunable surface chemistry, high electrical conductivity, and ease of solution processing, making them promising candidates for a wide array of applications. The inherent tendency of MXenes to degrade under environmental conditions constrains their compositional diversity and limits certain practical applications. Our computational study shows that degradation of defect-free Ti₃C₂Txis kinetically limited, whereas common defects markedly lower the activation barriers for water attack. Using ab initio molecular dynamics simulations (AIMD) combined with thermodynamic analysis, we show that titanium vacancies VTiact as active sites for the protonation of subsurface carbon …

Comparative Evaluation Of Dicyclohexylamine And N-Methyldiethanolamine As Corrosion Inhibitors For Top Of Line Corrosion On Api X80 Carbon Steel In Saturated Carbon Dioxide Aqueous Solutions, Frida W. Andalu, Abraham K. Temu, Alfred R. Akisanya, Joseph Yn Philip

Tanzania Journal of Science

This work has evaluated the efficiency of selected volatile corrosion inhibitors in mitigation of top of line corrosion in wet gas pipeline at different temperatures. The main challenge of top of line corrosion in carbon dioxide rich environment is the ability of the volatile corrosion inhibitor to effectively mitigate corrosion at adverse conditions. Electrochemical corrosion experiments using potentiodynamic polarization method were conducted at temperatures of 20 ℃, 35 ℃ and 45 °C to evaluate the efficiency of dicyclohexylamine and n-methyldiethanolamine corrosion inhibitors for top of line corrosion inhibition on carbon steel specimens derived from API X80 natural gas pipelines. The …

Dramatic Biases In Terrestrial Nitrogen Fixation In Earth System Models Revealed By Natural Isotope Signatures, Maoyuan Fang, Shushi Peng, Philippe Ciais, Daniel S. Goll, Benjamin Z. Houlton, Ying-Ping Wang, Yilong Wang, Pan Liu, Joshua B. Fisher, Pierre Regnier

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Biological nitrogen fixation (BNF) is the primary input of new reactive nitrogen to natural terrestrial ecosystems. However, this flux is poorly constrained due to its unclear drivers and associated control mechanisms. Here, we extend the existing theory of nitrogen (N) isotope mass balance to estimate BNF rates and then use a Bayesian approach to constrain the BNF rates in natural terrestrial ecosystems by using measurements of natural N-isotope ratios (δ¹⁵N) in plants (δ_P) and soil (δ_S). Together with pairwise δ_P and δ_S measurements from 18 forest sites covering diverse climates and thousands …