Playing catch and release with single molecules: mechanistic insights into plasmon-controlled nanogaps

Single-molecule (SM) detection is essential for investigating processes at the molecular level. Nanogap-based detection approaches have proven to be highly accurate SM capture and detection platforms in the last decade. Unfortunately, these approaches face several inherent drawbacks, such as short detection times and the effects of Brownian motion, that can hinder molecular capture. Nanogap-based SM detection approaches have been successfully coupled to optical-based setups to exploit nearfield-assisted trapping to overcome these drawbacks and thus improve SM capture and detection. Here we present the first mechanistic study of nearfield effects on SM capture and release in nanogaps, using unsupervised machine learning methods based on hidden Markov models. We show that the nearfield strength can manipulate the kinetics of the SM capture and release processes. With increasing field strength, the rate constant of the capture kinetics increase while the release kinetics decrease, favouring the former over the latter. As a result, the SM capture state is more likely and more stable than the release state above a specific threshold nearfild strength. We have also estimated the decrease in the capture free-energy profile and the increase in the release profiles to be around 5 kJ/mol for the laser powers employed, ranging from laser-OFF conditions to 11 mW/μm2. We envisage that our findings can be combined with the electrocatalytic capabilities of the (nearfield) nanogap to develop nextgeneration molecular nanoreactors. This approach will open the door to highly efficient SM catalysis with precise extended monitoring timescales facilitated through the longer residence times of the reactant trapped inside the nanogap

Comment on “Scanning-probe Raman spectroscopy with single-molecule sensitivity”

We reinterpret the scanning-probe Raman spectra shown in the paper of Neacsu et al. [Phys. Rev. B 73, 193406 (2006)] and compare it to a variety of single-molecule surface-enhanced Raman studies. The observed blinking behavior and spectral features must be attributed to carbon contaminations rather than to malachite green single molecules, because, under the given experimental conditions, the extremely high-field enhancement of 5x109 will inevitably lead to a quick (photo)decomposition of the adsorbate

Study of cost/benefit tradeoffs for reducing the energy consumption of the commercial air transportation system

Economic studies were conducted for three general fuel conserving options: (1) improving fuel consumption characteristics of existing aircraft via retrofit modifications; (2) introducing fuel efficient derivations of existing production aircraft and/or introducing fuel efficient, current state-of-the-art new aircraft; and (3) introducing an advanced state-of-the-art turboprop airplane. These studies were designed to produce an optimum airline fleet mix for the years 1980, 1985 and 1990. The fleet selected accommodated a normal growth market by introducing somewhat larger aircraft while solving for maximum departure frequencies and a minimum load factor corresponding to a 15% investment hurdle rate. Fuel burnt per available-seat-mile flown would drop 22% from 1980 to 1990 due to the use of more fuel efficient aircraft designs, larger average aircraft size, and increased seating density. An inflight survey was taken to determine air traveler attitudes towards a new generation of advanced turboprops

The Beam Conditions Monitor of the LHCb Experiment

The LHCb experiment at the European Organization for Nuclear Research (CERN) is dedicated to precision measurements of CP violation and rare decays of B hadrons. Its most sensitive components are protected by means of a Beam Conditions Monitor (BCM), based on polycrystalline CVD diamond sensors. Its configuration, operation and decision logics to issue or remove the beam permit signal for the Large Hadron Collider (LHC) are described in this paper.Comment: Index Terms: Accelerator measurement systems, CVD, Diamond, Radiation detector

The role of apex predators, habitat, and seascape complexity on nearshore fish assemblages in Southeast, Alaska

Dissertation (Ph.D.) University of Alaska Fairbanks, 2023Nearshore marine ecosystems contain dynamic and complex submerged vegetated habitats that offer shelter and prey for juvenile, migratory, and residential species, including many commercial, subsistence, and recreationally important species. The efficacy of the nursery role, shelter, and source of prey of the nearshore is influenced by various abiotic and biotic forces and in this dissertation, we examine the influence of submerged vegetation type, presence of apex predators, and the seascape context on patterns of nearshore fish assemblages in southern Southeast Alaska. We found species-specific responses by juvenile salmon in the nearshore, with seasonality overwhelmingly driving juvenile salmon abundance in eelgrass meadows and Chum Salmon present in greater abundance in understory kelp beds compared to eelgrass meadows, whereas Pink Salmon exhibited no difference. As a known apex predator, the reintroduction of sea otters likewise altered the nearshore fish assemblage with increased richness in eelgrass meadows and assemblage-wide shifts in understory kelps. Finally, in addition to habitat type and apex predators, spatial patterning and presence of adjacent vegetation can affect the nursery role of nearshore habitats. We observed differences in the fish assemblage in eelgrass meadows sampled in homogeneous seascapes with continuous eelgrass meadows and heterogeneous seascapes that included adjacent habitats, including more abundant commercial and forage species in heterogeneous seascapes. This research reinforces the importance of nearshore ecosystems in supporting robust fisheries and highlights the structuring role that submerged vegetation, apex predators, and complex seascapes have in sustaining diverse fish populations. Considering the greater ecological dynamics in the nearshore is vital for decision making in habitat conservation and management and for evaluating its role for fisheries, particularly in the context of increased threats to nearshore ecosystems.National Science Foundation Biological Oceanography grant (#1635716), Coastal Science, Engineering and Education for Sustainability (SEES) grant (#1600230), the Earthwatch Institute, National Science Foundation Graduate Research Fellowship, Biomedical Learning and Student Training (BLaST), Rasmuson Foundation, American Fisheries Society Hutton Scholarship, and Sealaska Heritage Institute ‘Opening the Box’ grant, Established Program to Stimulate Competitive Research (EPSCoR), the University of Alaska Fairbanks Graduate School, and the Alaska Chapter of the American Fisheries SocietyChapter 1: General introduction -- Chapter 2: Juvenile Chum and Pink Salmon use of submerged vegetative habitats in Southeast Alaska -- Chapter 3: Shifts in nearshore fish assemblages following reintroduction of an apex predator -- Chapter 4: Seascape complexity and habitat heterogeneity influences Alaskan eelgrass fish assemblages -- Chapter 5: General conclusion -- Appendices