About

Alexandra Hill is an Assistant Professor of Cooperative Extension in the Department of Agricultural & Resource Economics at the University of California, Berkeley. Her research centers around the US agricultural workforce, focusing on how various factors impact worker well-being, including income and health impacts, and how these factors influence business performance indicators such as productivity, output quality, profits, and workplace injuries. She investigates the economic, physical, legal, and emotional hardships faced by hired farmworkers, aiming to advance farmworker well-being and contribute to a more resilient and prosperous agri-food system. Her work seeks to identify ways to enhance the well-being of agricultural employees while maintaining or improving the economic viability of the businesses that employ them. Her research interests include agricultural labor, productivity, policy analysis, and air pollution related to agriculture.

Research topics

• Organic chemistry
• Chemistry
• Materials science
• Chemical engineering
• Composite material
• Nanotechnology
• Optoelectronics
• Chromatography
• Physics
• Chemical physics
• Optics
• Atomic physics
• Computational chemistry

Selected publications

• Measuring serotonin binding to its receptors <i>in vitro</i> via charge transfer to ANAP

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-10-03

  preprintOpen access

  Abstract Serotonin (5-HT) is a vital intercellular messenger with diverse signaling functions throughout the human body. We have characterized and implemented a novel, in vitro fluorescence-based method of measuring 5-HT binding to gain a fuller understanding of the interactions between 5- HT and its receptors. This method involves expression of 5-HT receptor proteins in cultured cells with the fluorescent, non-canonical amino acid L-3-(6-acetylnaphthalen-2-ylamino)-2- aminopropanoic acid (ANAP) incorporated into the ligand binding site. ANAP fluorescence was quenched in solution by both 5-HT and dopamine. Time-resolved photoluminescence and transient absorption spectroscopy confirmed that ANAP quenching by 5-HT occurs via a charge- transfer process that recovers through back-electron transfer on the nanosecond timescale. Supported by density functional theory calculations, this process likely involved a ANAP reduction by 5-HT. To test this method on intact receptors in a cellular context, we expressed 5- HT 3A receptors (5-HT-gated ion channels) in HEK293T cells with ANAP inserted co- translationally into the transmitter binding site. Fluorescently labeled 5-HT 3A receptors were functional and activated by 5-HT, as assessed by whole-cell patch clamp. Addition of 5-HT caused a concentration-dependent quenching of fluorescence from ANAP-tagged channels in intact cells and unroofed plasma membranes, demonstrating the utility of this method for measuring 5-HT binding to its receptors. Collectively, these results delineate a technique for measuring transmitter binding that can be widely adopted to explore 5-HT binding not only to 5- HT 3 receptors, but to any 5-HT receptor, transporter, or binding protein in heterologous expression systems.

  PublisherOA PDFDOI

• Water Transport Dynamics and Kinetic Equilibria in Nanoblisters at the Graphene–Mica Interface

  Langmuir · 2025-02-04

  articleOpen accessCorresponding

  Nanoscale reduced volumes with novel properties can be produced from 2D materials like graphene. Mild thermal annealing imposes vast and varied amounts of water intercalation into the graphene-mica interface, resulting in the formation of nanoblisters and impacting the local environment for applications such as reactions confined at the solid-solid interface. Atomic force microscopy imaging (AFM) and micro-Fourier transform infrared (micro-FTIR) spectroscopy characterization after 60-120 °C anneals revealed large volumes of water readily intercalate into graphene-mica nanoblisters, elucidating water transport behavior under mild reaction conditions. The inflation and deflation of graphene nanoblisters throughout the annealing process is attributed to the contraction of the graphene capping layer upon cooling from the annealing temperature, due to the independence of nanoblister aspect ratios from nanoblister volume or surface area. The intercalated water volume was estimated by the distended volumes of each nanoblister and exhibit an equilibrium trend established after 2 h of annealing. This water equilibrium occurs at a variety of temperatures, but higher temperatures favor graphene contraction and distention to accommodate larger volumes of water. Nanoblister volumes are set during the cooling process, indicating a kinetic trapping effect that can influence physical properties and reactivity for all systems confined at the graphene-mica interface.

  PublisherDOI

• Measuring Serotonin Binding to Its Receptors In Vitro via Charge Transfer to ANAP

  International Journal of Molecular Sciences · 2025-11-07 · 3 citations

  articleOpen access

  Serotonin (5-HT) is a vital intercellular messenger with diverse signaling functions throughout the human body. We have characterized and implemented a novel, in vitro fluorescence-based method of measuring 5-HT binding to gain a fuller understanding of the interactions between 5-HT and its receptors. This method involves expression of 5-HT receptor proteins in cultured cells with the fluorescent, non-canonical amino acid l-3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (ANAP) incorporated into the ligand binding site. ANAP fluorescence was quenched in solution by both 5-HT and dopamine. Time-resolved photoluminescence and transient absorption spectroscopy confirmed that ANAP quenching by 5-HT occurs via a charge-transfer process that recovers through back-electron transfer on the nanosecond timescale. Supported by density functional theory calculations, this process likely involved an ANAP reduction by 5-HT. To test this method on intact receptors in a cellular context, we expressed 5-HT3A receptors (5-HT-gated ion channels) in HEK293T cells with ANAP inserted co-translationally into the transmitter binding site. Fluorescently labeled 5-HT3A receptors were functional and activated by 5-HT, as assessed by whole-cell patch clamp. Addition of 5-HT caused a concentration-dependent quenching of fluorescence from ANAP-tagged channels in intact cells and unroofed plasma membranes, demonstrating the utility of this method for measuring 5-HT binding to its receptors. Collectively, these results delineate a technique for measuring transmitter binding that can be widely adopted to explore 5-HT binding not only to 5-HT3 receptors, but to any 5-HT receptor, transporter, or binding protein in heterologous expression systems.

  PublisherOA PDFDOI

• Time-Resolved Silica Luminescence Probes Photoinduced Electron Transfer from Heterobinuclear Units to 2,2′-Bipyridine and O₂

  The Journal of Physical Chemistry C · 2024-02-21

  articleSenior authorCorresponding

  Heterobinuclear units consisting of early and late transition metal ion pairs supported on a silica surface strongly absorb visible light, producing metal-to-metal charge transfer (MMCT) states with applications in renewable energy when units are coupled to electron donors or acceptors in integrated devices. Challenges to measuring these charge transfer pathways on subnanosecond time scales were surmounted using time-correlated single-photon counting (TCSPC) on self-supporting pressed pellets mounted in a 3D-printed aluminum gas cell. Following synthesis and characterization with spectroscopy and DFT, electron transfer from TiIVOCoII and ZrIVOCoII units to molecular electron shuttles and subsequently to luminescent silica trap states was measured on the sub-100 ps time scale using TCSPC. ZrIVOCoII units produced silica luminescence following excitation to a ZrIIIOCoIII MMCT state by transferring electrons via either 2,2′-bipyridine (bpy) or O2 shuttles; by comparison, analogous TiIVOCoII units excited to a TiIIIOCoIII MMCT state could produce luminescence with O2 but not bpy, despite showing equivalent coordination. This is evidence for rectifying behavior, in which electron transfer proceeds only in a single direction and depends on the relative arrangement of energy levels, because Zr(III) centers are capable of reducing bpy, but Ti(III) centers are not. Transport through the bpy-ZrOCo electron transfer chain takes place in 110 ± 20 ps; analogous samples showed similar time scales. The resulting silica luminescence exhibited peaks at 450 nm (2.8 eV) and 560 nm (2.2 eV), which decayed, as fit with an Albery-type function, with lifetimes of around 200 ps and 2 ns and dispersions of 3 and 4, respectively. Quenching of emission from bpy-ZrOCo samples by O2 supported its crossover from an S = 3/2 to an S = 1/2 state along the charge transfer pathway. These results demonstrate the application of rectifying principles for the development of devices for artificial photosynthesis as well as the use of silica photoluminescence as a low-noise probe of electron transfer processes in systems that do not otherwise luminesce.

  PublisherDOI

• Exploring Resonance Raman Scattering with 4-Nitrophenol

  Journal of Chemical Education · 2022 · 19 citations

  Senior authorCorresponding
  • Chemistry
  • Optics
  • Materials science

  Raman scattering is a powerful tool for revealing the vibrations of molecules, but as a nonlinear optical phenomenon, its signals can change via mechanisms like resonance enhancement that have no direct analogue in infrared spectroscopy. In this work, complementary measurements conducted on 4-nitrophenol and its conjugate base allow students to directly control the variables responsible for enhancement. Changing sample UV–vis absorbance with pH and excitation color with the addition of a diode laser allows students to explore the criteria for resonance Raman scattering: only the conjugate base and 405 nm laser in combination produce enhancement. Adjustments to the experiment make it suitable for either an upper-level undergraduate course lab or an independent inquiry project.

  PublisherDOI

• Enhanced Crystallinity of Covalent Organic Frameworks Formed Under Physical Confinement by Exfoliated Graphene

  Small · 2022 · 5 citations

  • Materials science
  • Chemical engineering
  • Nanotechnology

  The polymerization of 1,4-benzenediboronic acid (BDBA) on mica to form a covalent organic framework (COF-1) reveals a dramatic increase in crystallinity when physically confined by exfoliated graphene. COF-1 domains formed under graphene confinement are highly geometric in shape and on the order of square micrometers in size, while outside of the exfoliated flakes, the COF-1 does not exhibit long-range mesoscale structural order, according to atomic force microscopy imaging. Micro-Fourier transform infrared spectroscopy confirms the presence of COF-1 both outside and underneath the exfoliated graphene flakes, and density functional theory calculations predict that higher mobility and self-assembly are not causes of this higher degree of crystallinity for the confined COF-1 domains. The most likely origin of the confined COF-1's substantial increase in crystallinity is from enhanced dynamic covalent crystallization due to the water confined beneath the graphene flake.

  PublisherDOI

• Spectroscopic and computational evidence for the concerted mechanism of the Wagner‐Jauregg reaction

  Journal of Physical Organic Chemistry · 2020 · 6 citations

  Senior authorCorresponding
  • Chemistry
  • Computational chemistry
  • Organic chemistry

  Abstract The Wagner‐Jauregg reaction, despite its potential utility, has remained largely unexplored since its discovery in 1930. Utilizing density functional theory (DFT) calculations and experimental 1 H nuclear magnetic resonance (NMR) kinetics data to generate a Hammett plot, the reaction is shown to proceed via a highly asynchronous, concerted mechanism, analogous to the Diels–Alder reaction. Our development of milder, more reliable reaction conditions for the Wagner‐Jauregg reaction will facilitate the synthesis of novel, structurally complex, polycyclic molecules.

  PublisherDOI

• The Liberal Arts Science Scholars Program: A Multidisciplinary Model for Supporting Science and Mathematics Students through the First Year.

  Journal of STEM education · 2019-01-01 · 2 citations

  articleOpen access
  Publisher

• Photoinduced Electron Transfer from ZrOCo Binuclear Light Absorber to Pyridine Elucidated by Transient Optical and Infrared Spectroscopy

  The Journal of Physical Chemistry C · 2018-08-09 · 11 citations

  articleOpen access1st authorCorresponding

  All-inorganic heterobinculear units can be excited to a metal-to-metal charge transfer (MMCT) state by visible and ultraviolet light and form the core of multicomponent artificial photosystems that rely on conjugated molecular wires to transmit electrons and holes across ultrathin silica separation membranes to catalytic sites. To understand electron transfer from a heterobinuclear unit to an organic molecule, model systems consisting of pyridine interacting with ZrIVOCoII or TiIVOCoII sites on silica nanoparticles were assembled and spectroscopically characterized. Transient optical absorption spectroscopy combined with infrared analysis revealed that visible light excitation of assemblies in which pyridine interacts with the Zr center of the ZrOCo unit results in sub-10 ns separation by electron transfer to the organic moiety. Rapid-scan FT-IR spectroscopy supported by density functional theory confirmed the identity of the pyridine radical anion charge-separated state. This state shows a lifetime of 220 (±60) ms prior to complete recovery of the initial state, suggesting spin crossover along the electron transfer path. No hole transfer from excited ZrIVOCoII → ZrIIIOCoIII to pyridine is observed. The rectifying charge transfer behavior is an important design aspect for developing efficient artificial photosystems.

  PublisherOA PDFDOI

• Genitourinary Trauma

  DeckerMed Transitional Year Weekly Curriculum™ · 2018-08-19

  articleSenior author

  Injury to the urogenital tract from blunt or penetrating trauma comprises 10% of injuries sustained from trauma with renal injuries comprising the majority of those cases at 1-5 % of all trauma, followed by bladder injuries. Worldwide variations in trauma mechanisms exist, with blunt trauma causing the majority of renal trauma in the United States. Careful attention to the mechanism, anatomic location, and specific physical and radiologic findings can aid in the diagnosis and appropriate management to optimize patient outcomes. Unless trauma is overtly obvious on a physical examination, imaging is required for diagnosis and staging purposes. Owing to the complexity of the urogenital tract, there is a great deal of variation in management, ranging from a conservative approach in most renal injuries to the need for operative intervention with intraperitoneal bladder rupture. This review discusses common practice and provides more recent up-to-date guidelines pertaining to the clinical history, examination findings, and imaging modalities, along with the diagnosis and management of injuries to the genitourinary system. Keywords: Genitourinary Trauma, Renal Trauma, Ureter Trauma, Bladder Trauma, Urethral Trauma, External Genitalia Trauma

  PublisherDOI

Frequent coauthors

• Charles B. Harris

  15 shared

• Son C. Nguyen

  University of California, Merced

  14 shared

• Justin P. Lomont

  United States Military Academy

  14 shared

• Jacob P. Schlegel

  University of Konstanz

  12 shared

• Matthew C. Zoerb

  California Polytechnic State University

  12 shared

• Georgios Katsoukis

  University of Twente

  5 shared

• Heinz Frei

  University of California, Berkeley

  5 shared

• A. Lehman

  University of Cagliari

  4 shared