Simplifying the Quantum World: Demonstrations for Young Learners in an Informal Setting

Journal of Chemical Education · 2025-11-23 · 1 citations

A set of modules for the informal learning of quantum science was developed. They include (1) Waves and Bottling Light in Quantum Dots, (2) Quantization of Energy Levels, (3) Particle-Wave Duality, (4) Magnetism and Electron Spin, and (5) Quantum Entanglement. Their teaching objective is to clarify concepts in quantum science, and they have been presented together as part of an hour-long show to ∼250 adults and school-age children. The learning outcomes of the modules were assessed by pre- and postevent quizzes as well as interactive clicker questions. The results suggest effective learning of all of the assessed concepts. These modules are detailed in a way that makes them deployable, together or in part, in other formal or informal settings to support the dissemination of information about quantum science to the general public.

A New Spectroscopic Probe of Nonequilibrium Dynamics at Gas-Condensed Phase Interfaces

The Journal of Physical Chemistry Letters · 2025-02-20

GABAergic modulation of beta power enhances motor adaptation in frontotemporal lobar degeneration

Alzheimer s & Dementia · 2025-02-19 · 1 citations

INTRODUCTION: We examined how abnormal prefrontal neurophysiology and changes in gamma-aminobutyric acid-ergic (GABAergic) neurotransmission contribute to behavioral impairments in disorders associated with frontotemporal lobar degeneration (FTLD). METHODS: We recorded magnetoencephalography during an adaptive visuomotor task from 11 people with behavioral-variant frontotemporal dementia, 11 with progressive supranuclear palsy, and 20 age-matched controls. We used tiagabine, a gamma-aminobutyric acid (GABA) re-uptake inhibitor, as a pharmacological probe to assess the role of GABA during motor-related beta power changes. RESULTS: Task impairments were associated with diminished movement-related beta power. Tiagabine facilitated partial recovery of behavioral impairments and neurophysiology, moderated by executive function, such that the greatest improvements were seen in those with higher cognitive scores. The right prefrontal cortex was revealed as a key site of drug interaction. DISCUSSION: Behavioral and neurophysiological deficits can be mitigated by enhancement of GABAergic neurotransmission. Clinical trials are warranted to test for enduring clinical benefits from this restorative-psychopharmacology strategy. HIGHLIGHTS: Event-related beta power changes during movement can be altered by the GABA reuptake inhibitor, tiagabine. In people with behavioral-variant frontotemporal dementia and progressive supranuclear palsy, tiagabine enhanced beta modulation and concurrently improved task performance, dependent on baseline cognition, and diagnosis. The effects of the drug suggest a GABA-dependent beta-related mechanism that underlies adaptive motor control. Restoring selective deficits in neurotransmission is a potential means to improve behavioral symptoms in patients with dementia.

Novel Optical Parametric Oscillator Design for High-Power, High-Resolution, Frequency-Stable, CW Infrared Spectroscopic Applications

The Journal of Physical Chemistry A · 2025-10-28

We present results for novel design and implementation of a high-power, high-resolution continuous-wave optical parametric oscillator (OPO) emitting mid-infrared radiation tunable from 3–4 μm, with output powers in excess of 2.5 W. Our home-built “JILA OPO” design is based on a periodically poled lithium niobate fanout crystal inside a four-mirror ring cavity singly resonant at the signal wavelength (1.4–1.7 μm). The 50 mm-long fanout crystal is pumped by a single-mode, narrow-line width continuous-wave 1064 nm fiber laser, which achieves an oscillation threshold of 2 W. For long-term frequency stabilization and control, we actively lock the OPO to an optical transfer cavity (OTC), which is in turn locked to a polarization-stabilized HeNe laser to achieve root-mean-square noise of ≤2.3(2) MHz within 10 ms and absolute OPO idler frequency drifts of <1 MHz/hour. The high output power and narrow line width of the OPO are demonstrated via saturated absorption spectroscopy on the ν3 P(7) transition of CH4 (40–300 mTorr) in a retroreflecting double-pass cell, for which narrow Lamb dips with a full width at half-maximum (fwhm) of 3.1(1) MHz are readily observed. Technical aspects of our monolithic laser block construction, thermal cooling, optical transfer cavity, electronic servo loop control, mirror selection, and beam size considerations for optimal low pumping threshold, long-term frequency stability, and maximal conversion efficiency are presented, with further details available on request.

Thermodynamic compensation to temperature extremes in B. subtilis vs T. maritima lysine riboswitches

Biophysical Journal · 2024-07-31

GABAergic modulation of beta power enhances motor adaptation in frontotemporal lobar degeneration

medRxiv · 2024-06-30 · 1 citations

Abstract The impairment of behavioural control is a characteristic feature of disorders associated with frontotemporal lobar degeneration (FTLD). Behavioural disinhibition and impulsivity in these disorders are linked to abnormal neurophysiology of the frontal lobe, such as the loss beta-band power and changes in prefrontal GABAergic neurotransmission. Here we test the hypothesis that a pharmacological increase of GABA would concurrently improve cortical beta-band power and adaptive behavioural control in people with behavioural-variant frontotemporal dementia (bvFTD), and progressive supranuclear palsy (PSP, Richardson’s syndrome). We recorded magnetoencephalography during a visuomotor task that measures participants’ ability to adapt motor responses to visual feedback. Tiagabine, a GABA re-uptake inhibitor, was used as a pharmacological probe in a double-blind placebo controlled crossover design. The study included 11 people with bvFTD, 11 people with PSP and 20 healthy age-matched controls. Behavioural performance and beta power were examined with linear mixed models examined changes in, to estimate motor learning over time and the response to tiagabine. Significant beta power differences were source-localised using linear-constraint minimum variance beamformer. As predicted, participants with bvFTD and PSP were impaired behaviourally, and the beta power associated with movement, learning and accuracy, was diminished compared to controls. Tiagabine facilitated partial recovery of the impairments in behaviour and beta power over trials, moderated by executive function, such that the greatest improvements were seen in those with higher cognitive scores. The beamformer localised the physiological effects of disease and tiagabine treatment to frontal cortices, and confirmed the right prefrontal cortex as a key site of drug by group interaction. We interpret the differential response to tiagabine between bvFTD and PSP as a function of baseline differences in atrophy and physiology. In summary, behavioural and neurophysiological deficits can be mitigated by enhancement of GABAergic neurotransmission. Clinical trials are warranted to test for enduring clinical benefits from this restorative-psychopharmacology strategy.

Observation of full contrast icosahedral Bose-Einstein statistics in laser desorbed, buffer gas cooled C$_{60}$

arXiv (Cornell University) · 2024-06-20 · 1 citations

The quantum mechanical nature of spherical top molecules is particularly evident at low angular momentum quantum number J. Using infrared spectroscopy on the 8.4$μ$m rovibrational band of buffer gas cooled $^{12}$C$_{60}$, we observe the hitherto unseen R(J = 0 - 29) rotational progression, including the complete disappearance of certain transitions due to the molecule's perfect icosahedral symmetry and identical bosonic nuclei. The observation of extremely weak C$_{60}$ absorption is facilitated by a laser desorption C$_{60}$ vapor source, which transfers 1000-fold less heat to the cryogenic buffer gas cell than a traditional oven source. This technique paves the way to cooling C$_{60}$ and other large gas phase molecules to much lower temperatures, providing continued advances for spectral resolution and sensitivity.

Ultrasensitive cavity-enhanced frequency comb breath spectroscopy for point-of-care medical diagnostics

2024-03-13

This talk reflects a collaboration between Ye/Nesbitt groups to use of broad-band, ultrastable infrared frequency comb light sources in the 3-5 and 5-10 m IR fingerprint region with high finesse resonant cavities to probe small molecule content in exhaled human breath. These methods offer as much as a 100-million-fold enhancement in sensitivity x spectral throughput over conventional approaches, which in combination with machine learning algorithms have permitted encouraging first successes in real time identification of COVID disease state.

Ionic Cooperativity between Lysine and Potassium in the Lysine Riboswitch: Single-Molecule Kinetic and Thermodynamic Studies

The Journal of Physical Chemistry B · 2023-03-14 · 7 citations

Functionality in many biological systems, including proteins and nucleic acid structures, including protein and nucleic acid riboswitch structures, can depend on cooperative kinetic behavior between multiple small molecule ligands. In this work, single-molecule FRET data on the Bacillus subtilis lysine riboswitch reveals that affinity for the cognate lysine ligand increases significantly with K+, providing evidence for synergism between lysine/K+ binding to the aptamer and successful folding of the riboswitch. To describe/interpret this more complex kinetic scenario, we explore the conventional 4-state (“square”) model for aptamer binding as a function of K+. Extension into this additional dimension generates a novel “cube” model for riboswitch folding dynamics with respect to lysine/K+ binding, revealing that riboswitch folding (kfold) and unfolding (kunfold) rate constants increase and decrease dramatically with K+, respectively. Furthermore, temperature-dependent single-molecule kinetic studies indicate that the presence of K+ entropically enhances the transition state barrier to folding but partially compensates for this by increasing the overall exothermicity for lysine binding. We rationalize this behavior as evidence that K+ facilitates hydrogen bonding between the negatively charged carboxyl group of lysine and the RNA, increasing structural rigidity and lowering entropy in the binding pocket. Finally, we explore the effects of cation size with Na+ and Cs+ studies to demonstrate that K+ is optimally suited for bridging interactions between lysine and the riboswitch aptamer domain. Regulation of lysine production and transport, dictated by the riboswitch’s ability to recognize and bind lysine, is therefore intimately tied to the presence of K+ in the binding pocket and is strongly modulated by local cation conditions. The results suggest an increase in lysine riboswitch functionality by sensitivity to additional species in the cellular riboswitch environment.

Kinetic and Thermodynamic Control of G-Quadruplex Polymorphism by Na⁺ and K⁺ Cations

The Journal of Physical Chemistry B · 2023-07-28 · 20 citations

G-Quadruplexes (G4s) are ubiquitous nucleic acid folding motifs that exhibit structural diversity that is dependent on cationic conditions. In this work, we exploit temperature-controlled single-molecule fluorescence resonance energy transfer (smFRET) to elucidate the kinetic and thermodynamic mechanisms by which monovalent cations (K+ and Na+) impact folding topologies for a simple G-quadruplex sequence (5′-GGG-(TAAGGG)3-3′) with a three-state folding equilibrium. Kinetic measurements indicate that Na+ and K+ influence G4 formation in two distinctly different ways: the presence of Na+ modestly enhances an antiparallel G4 topology through an induced fit (IF) mechanism with a low affinity (Kd = 228 ± 26 mM), while K+ drives G4 into a parallel/hybrid topology via a conformational selection (CS) mechanism with much higher affinity (Kd = 1.9 ± 0.2 mM). Additionally, temperature-dependent studies of folding rate constants and equilibrium ratios reveal distinctly different thermodynamic driving forces behind G4 binding to K+ (ΔH°bind > 0, ΔS°bind > 0) versus Na+ (ΔH°bind < 0, ΔS°bind < 0), which further illuminates the diversity of the possible pathways for monovalent facilitation of G-quadruplex folding.