National Research Council Canada

Spectra of the weakly bound H2O–O2 dimer are studied in the region of the H2O ν2 band using a tunable quantum cascade laser to probe a pulsed supersonic slit jet expansion. These are the first gas-phase infrared spectra of H2O–O2 and among only a few such results for O2-containing complexes. Almost 100 infrared lines are assigned based on the ground state combination differences from the microwave spectrum of H2O–O2. These lines belong to a main fundamental band, plus four combination bands lying 2 to 5 cm⁻¹ above the fundamental. All correspond to the ortho-H2O (I = 1) nuclear spin species. Interpretation of the observed rotational levels is discussed. The original microwave analysis conflicts with the infrared results but can be corrected by changing the sign of a term or, better still, by using a published theory for weakly bound open shell complexes. The combination bands suggest that analogous ground state bands should be observable in the millimeter wave range. Many infrared transitions remain unassigned, including another extensive band apparently centered at 1603 cm⁻¹, and some of these are probably due to the para-H2O spin species (I = 0). Splittings due to the unpaired O2 electron spin (S = 1), due to large amplitude tunneling motions, and due to a-axis rotational motion all have similar magnitudes for H2O–O2, so the resulting energy levels will be heavily mixed and not amenable to simple modeling. Accurate theoretical predictions of these effects should be possible for obtaining an enhanced understanding of the observed spectra.

A nonlinear optical platform is presented to emulate a nonlinear Lévy waveguide that supports the pulse propagation governed by a generalized fractional nonlinear Schrödinger equation (FNLSE). This approach distinguishes between intra-cavity and extra-cavity regimes, exploring the interplay between the effective fractional group-velocity dispersion (FGVD) and Kerr nonlinearity. In the intra-cavity configuration, stable fractional solitons enabled by an engineered combination of the fractional and regular dispersions in the fiber cavity are observed. The soliton pulses exhibit their specific characteristics, viz., "heavy tails" and a "spectral valley" in the temporal and frequency domain, respectively, highlighting the effective nonlocality introduced by FGVD. Further investigation in the extra-cavity regime reveals the generation of spectral valleys with multiple lobes, offering potential applications to the design of high-dimensional data encoding. To elucidate the spectral valleys arising from the interplay of FGVD and nonlinearity, an innovative "force" model supported by comprehensive numerical analysis is developed. These findings open new avenues for experimental studies of spectral-temporal dynamics in fractional nonlinear systems.

To achieve higher engine combustion efficiency while reducing emissions, it is necessary to address the challenges posed by elevated operating temperatures. High entropy alloys (HEAs) have emerged as promising materials for this purpose, offering exceptional properties at high temperatures, including synergistic effects and excellent resistance to oxidation and corrosion. In this study, a FeCoNiCrAl HEA was investigated as a bond coat material due to its excellent balance of strength and ductility, coupled with outstanding oxidation resistance. It was deposited using HVAF M3 and i7 guns equipped with different nozzles/powder injectors and pressures. Notably, this research marks the first study of the i7 gun globally for the HEA bond coat, coupled with the optimization of HVAF parameters for both i7 and M3 guns. Characterization of both powder and as-sprayed samples was carried out using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and field emission scanning electron microscopy (FESEM) techniques. The results revealed the formation of a dense and homogeneous microstructure. Additionally, isothermal oxidation tests were conducted to analyze the behavior of the thermally grown oxide. After 50 hours at 1000 °C, a dense, uniform, and thin alumina TGO layer was observed to have formed. These tests revealed that FeCoNiCrAl HEA exhibits significant potential to enhance oxidation resistance at high temperatures.

Background Iduronate-2-sulfatase (IDS) deficiency (MPS II; Hunter syndrome) is a disorder that exhibits peripheral and CNS pathology. The blood brain barrier (BBB) prevents systemic enzyme replacement therapy (ERT) from alleviating CNS pathology. We aimed to enable brain delivery of systemic ERT by using molecular BBB-Trojans targeting endothelial transcytosis receptors. Methods: Single-domain antibody (sdAb)-enzyme fusion protein constructs were prepared in Yarrowia lipolytica. sdAb affinity and BBB permeability were characterized using SPR and an in vitro rodent BBB assay, respectively. In vivo pharmacokinetic (PK) analysis was performed in rats. Quantification of fusion protein amounts were performed using LC-MS. Results Fusion proteins consisting of IDS and BBB-transmigrating sdAbs, albumin binding sdAbs or human serum albumin (HSA) were evaluated for their in vitro BBB permeability. IGF1R3H5-IDS was selected for in vivo PK analysis in rats. IDS and IGF1R3H5-IDS exhibited very short (< 10 min) serum half-life (t1/2α), while constructs containing either HSA or anti-serum albumin sdAbs (R28 or M79) showed 8–11 fold increases in the area under the curve (AUC) in serum. CSF analysis indicated that IGF1R3H5 increased brain exposure by 9 fold (AUC) and constructs containing HSA or R28 exhibited 42–52 fold increases. Quantitation of brain levels confirmed the increased and sustained delivery of IDS to the brain of HSA- and R28-containing constructs. Lastly, analysis of brain fractions demonstrated that the increases in brain tissue were due to parenchymal delivery without fusion protein accumulation in brain vessels. Conclusions These results demonstrate the utility of IGF1R-targeting sdAbs to effect brain delivery of lysosomal enzymes, as well as the utility of serum albumin-targeting sdAbs in t1/2 extension, to increase brain delivery of rapidly cleared enzymes.

Road tunnels are enclosed spaces that most occupants only experience while driving through them. In case of fire, however, occupants potentially need to evacuate on foot from a dangerous and unfamiliar environment. Clear and accurate guidance is important for an efficient and safe evacuation from tunnels. Common cues for evacuation guidance are a signage and audio messages that attract occupants to move on appropriate egress routes and avoid unsafe routes. This paper investigates how different types of visual and auditory signals influence occupants’ exit choices in a simulated tunnel evacuation. Common guidance cues were presented to participants in a mobile Head Mounted Display, and they were asked to choose between two possible exit doors in a simulated road tunnel. Two attracting cues (“EXIT” signs, audio instructions), and two detracting cues (“DO NOT ENTER” signs; traffic cones placed in front of an exit) were studied in three virtual reality (VR) experiments. In each experiment, the presence and direction of the cues were manipulated, and data from 20 participants were collected. Experiment 1 explored the effects of attracting cues, Experiment 2 detracting cues, and Experiment 3 the combination of attracting and detracting cues. Across all studies, participants tended to follow the guidance provided when there was only one cue. When several competing and even contradictory cues were present, participants were most likely to rely on audio instructions, followed by traffic cones and “DO NOT ENTER” signs, whereas “EXIT” signs were often disregarded. We conclude that participants tend to follow temporary cues that could carry current information, as opposed to permanently installed signage. Some corresponding suggestions are put forward on evacuation system design and strategic planning in a tunnel fire.

Raman spectroscopy is a powerful method for probing electronic and vibrational properties of materials, particularly nanomaterials such as single-wall carbon nanotubes. Typically, Raman spectroscopy is conducted at a single, or few, excitation wavelengths, but that provides limited information about excitation resonance structure, and their dynamical evolution. Here, we extend a sensitive full-spectrum technique to rapidly obtain two-dimensional Raman excitation maps both statically and dynamically for chirality-pure single-wall carbon nanotube films. We demonstrate sensitive evaluation of structured resonance profiles even from weak vibrational modes, and sub-second time resolution of the dynamics of photo-driven defect production. Findings include the direct observation of bands and their profiles – including bands which could be missed in conventional Raman spectroscopy - and demonstration of differences for odd vs. even defect band combinations. This opens up possibilities to investigate the coupling of electronic states with vibrational modes in nanomaterials and track their dynamical evolution subject to intentional modulation.

Monitoring the structural health of composites during manufacturing and in‐service is desirable to alert against damage or deterioration of conditions beyond an acceptable level. Wireless sensors embedded into materials that can endure the forming and curing of carbon fiber‐reinforced polymer laminates will open the door to automated near‐field detection of key metrics such as temperature, strain, and manufacturing defects. Current sensing technologies are generally too intrusive and fragile to be reliably embedded into laminates or too expensive to be applied commercially. The development of embedded, low‐weight, small‐footprint sensors is reported here, and how these sensors can be used to monitor ply movement during the manufacturing process is demonstrated. These screen‐printed sensors consist of closed‐loop spiral coils excited externally with an AC magnetic field to generate a secondary field, which alerts on the change of relative position of each ply. This proof‐of‐concept work demonstrates how printed coil sensors can be fabricated to generate a high electromagnetic response, while minimizing their footprint in the laminate. It is determined that stacked silver coils, which are subsequently plated with copper to increase the conductance, are capable of producing signals that can be detected through over 3 mm of composite material.

Adult children often help their older parents maintain independence at home, and this informal caregiving can be overwhelming and challenging to balance with other aspects of life. Yet, adult children's requirements tend to be overlooked when designing technologies to foster aging in place. In this work, we use reflexive thematic analysis to study Reddit content to understand the experiences of adult caregivers and the issues that they face in supporting their parents. The pseudonymous data allowed us to explore three research questions: 1) What are the experiences of adult children as informal helpers for elderly parents? 2) How do adult children currently manage their role as informal helpers? and 3) How might digital technology facilitate communication between aging parents and adult children as informal helpers? Our findings lead to a number of design considerations for technologies that support adult children caring for parents who are aging in place, including: building common ground, establishing boundaries, addressing guilt, encouraging in-person communication, community support for adult children, and adapting to changes in role reciprocity.

Background Agitation, manifesting as aggressive and non‐aggressive behaviors, is one of the most common neuropsychiatric symptoms in Alzheimer’s dementia, presenting in approximately half of all patients. Despite the high prevalence, recognition of agitation in Alzheimer’s dementia (AAD) remains a challenge that impacts timely diagnosis and treatment. The International Psychogeriatric Association (IPA) established a new standard definition of agitation in cognitive disorders, which provides guidance for advancing recognition and improving patient care. The Agitation in Alzheimer’s Screener for Caregivers (AASC™), an easy‐to‐use and pragmatic tool, was developed based on IPA criteria to support caregivers and healthcare professionals (HCPs) in recognizing AAD, thereby facilitating caregiver‐HCP discussions and supporting timely treatment planning. Method The AASC™ was developed and qualitatively evaluated through a rigorous, iterative process involving clinical experts, patients, and caregivers. For quantitative validation, this prospective, multisite, single‐visit observational study will calculate predictive metrics for the identification of agitation by comparing responses on the AASC™, completed by caregivers, to HCPs judgement based on implementation of the IPA criteria (Figure 1). Community‐dwelling patients must have a recorded diagnosis of Alzheimer’s dementia; caregivers must be aged 18‐85 years, provide patient care ≥10 hours/week, and attend the office visit. Data will be collected and analyzed in 2 parts: an interim analysis (n = 50 dyads) will determine the rate of agreement (yes/no), and a final analysis (n = 150 dyads) will determine sensitivity and specificity of the AASC™. Caregiver‐reported items include caregiver and patient demographics and AASC™ responses. HCPs will complete assessments for the presence of IPA‐defined agitation and the severity of Alzheimer’s dementia. Result Results will include: descriptive statistics, the percentage agreement and Cohen’s kappa coefficient characterizing the interrater reliability between the caregiver‐completed AASC™ and IPA‐based HCP decision (part 1), sensitivity, specificity, positive and negative predictive values of the AASC™ against the HCP decision, goodness of fit metrics (e.g., concordance), and receiver operating characteristic curves (part 2). Conclusion The AASC™ was developed following a rigorous process established to support its medical credibility and implementation in clinical practice. Results from this study will quantitatively validate the AASC™, leveraging caregiver observations to aid in facilitating earlier identification and treatment of AAD.

Advancements in live audio processing, specifically in sound classification and audio captioning technologies, have widespread applications ranging from surveillance to accessibility services. However, traditional methods encounter scalability and energy efficiency challenges. To overcome these, Triboelectric Nanogenerators (TENG) are explored for energy harvesting, particularly in live‐streaming sound monitoring systems. This study introduces a sustainable methodology integrating TENG‐based sensors into live sound monitoring pipelines, enhancing energy‐efficient sound classification and captioning by model selection and fine‐tuning strategies. Our cost‐effective TENG sensor harvests ambient sound vibrations and background noise, producing up to 1.2 µW cm⁻² output power and successfully charging capacitors. This shows its capability for sustainable energy harvesting. The system achieves 94.3% classification accuracy using the Hierarchical Token Semantic Audio Transformer (HTS‐AT) model identified as optimal for live sound event monitoring. Additionally, continuous audio captioning using the EnCodec Combining Neural Audio Codec and Audio‐Text Joint Embedding for Automated Audio Captioning model (EnCLAP) showcases rapid and precise processing capabilities that are suitable for live‐streaming environments. The Bidirectional Encoder representation from the Audio Transformers (BEATs) model also demonstrated exceptional performance, achieving an accuracy of 97.25%. These models were fine‐tuned using the TENG‐recorded ESC‐50 dataset, ensuring the system's adaptability to diverse sound conditions. Overall, this research significantly contributes to the development of energy‐efficient sound monitoring systems with wide‐ranging implications across various sectors.

This article gives the author's perspective on the history of the development of the molecular symmetry (MS) group. It explains how the initial work of Hougen, which was developed for nonlinear rigid molecules, inspired Longuet‐Higgins to introduce nuclear permutations and the inversion as the fundamental elements of molecular symmetry. The symmetry group that is obtained applies to all molecules, rigid or nonrigid. The criticism of Altmann, and the rebuttal of that work by Watson, is described. Altmann's work had the unfortunate effect of delaying the appreciation of Longuet‐Higgins' ideas.

Time is a central dimension against which perception, action, and cognition play out. From anticipating when future events will happen to recalling how long ago previous events occurred, humans and animals are exquisitely sensitive to temporal structure. Empirical evidence seems to suggest that estimating time prospectively (i.e., in passing) is qualitatively different from estimating time in retrospect (i.e., after the event is over). Indeed, computational models that attempt to explain both prospective and retrospective timing assume a fundamental separation of their underlying processes. We, in contrast, propose a new neurocomputational model of timing, the unified temporal coding (UTC) model that unifies prospective and retrospective timing through common principles. The UTC model assumes that both stimulus and timing information are represented inside the same rolling window of input history. As a consequence, the UTC model explains a wide range of phenomena typically covered by specialized models, such as conformity to and violations of the scalar property, one-shot learning of intervals, neural responses underlying timing, timing behavior under normal and distracting conditions, common capacity limits in timing and working memory, and how timing depends on attention. Strikingly, by assuming that prospective and retrospective timing rely on the same principles and are implemented in the same neural network, a simple attentional gain mechanism can resolve the apparently paradoxical effect of cognitive load on prospective and retrospective timing.

The rational design of engineered nanomaterials (NMs) with improved functionality and their increasing industrial application requires reliable, validated, and ultimately standardized characterization methods for their application-relevant, physicochemical key properties such as size, size distribution, shape, or surface chemistry. This calls for nanoscale (certified) reference materials (CRMs; RMs) and well-characterized reference test materials (RTMs) termed also quality control (QC) samples, assessed, e.g., in interlaboratory comparisons, for the validation and standardization of commonly used characterization methods. Thereby, increasing concerns regarding potential risks of NMs are also addressed and the road for safe and sustainable-by-design concepts for the development of new functional NMs and their use as nanomedicines is paved. With this respect, we will provide an overview of relevant international standardization and regulatory activities, definitions, and recommendations on characterization methods and review currently available organic or inorganic nanoscale CRMs, RMs, and RTMs, including their characterization or certification. In addition, we will highlight typical applications to streamline the regulatory approval process and improve manufacturability including the special challenges imposed by the colloidal nature and sometimes limited stability of NMs. Subsequently, we will critically assess the limitations of currently available nanoscale RMs and RTMs and address the gaps to be filled in the future such as the availability of NMs that come with reference data on properties other than commonly addressed particle size, such as surface chemistry or particle number concentration, or more closely resemble commercially available formulations or address application-relevant matrices. Graphical Abstract

We report a nonlinear terahertz (THz) detection device based on a metallic bull’s-eye plasmonic antenna. The antenna, fabricated with femtosecond laser direct writing and deposited on a nonlinear gallium phosphide (GaP) crystal, focuses incoming THz waveforms within the sub-wavelength bull’s eye region to locally enhance the THz field. Additionally, the plasmonic structure minimizes diffraction effects allowing a relatively long interaction length between the transmitted THz field and the co-propagating near-infrared gating pulse used in an electro-optic sampling configuration. We show an increased detection sensitivity over a large spectral range extending from 1.4 THz to 3.1 THz with a peak enhancement factor of 3.1 at 2.7 THz. We demonstrate that this plasmonic structure is especially effective in monitoring THz signals affected by beam wandering or varying spot sizes. Our concept can be adapted to any second-order nonlinear crystal to realize compact and sensitive THz detectors without the need for tight beam focusing or high-precision alignment. This work paves the way for future developments of compact and sensitive THz detectors, notably for applications in wireless communications.

This study evaluates and compares four millimeter-wave (mmWave) radio-over-fiber (RoF) frequency multiplexing techniques considering InAs/InP quantum dash (QD) mode-locked lasers (MLLs) for optical carriers. The QD-MLL can generate multiple coherent optical carriers simultaneously with consistent frequency differences. Following heterodyne detection, the radio frequency linewidths of the QD-MLL can be minimized to 2.4 kHz. In this paper, four distinct RoF-based mmWave frequency multiplexing architectures are presented and compared experimentally. It is shown that the error vector magnitude of two 2 GBaud/s 16-QAM mmWave signals can reach as low as 7.1% after demultiplexing for all four techniques.

Dry deposition is an important yet poorly constrained process that removes reactive organic carbon from the atmosphere, making it unavailable for airborne chemical reactions and transferring it to other environmental systems. Using an aircraft-based measurement method, we provide large-scale estimates of total gas-phase organic carbon deposition rates and fluxes. Observed deposition rates downwind of large-scale unconventional oil operations reached up to 100 tC hour ⁻¹ , with fluxes exceeding 0.1 gC m ⁻² hour ⁻¹ . The observed deposition lifetimes (τ dep ) were short enough (i.e., 4 ± 2 hours) to compete with chemical oxidation processes and affect the fate of atmospheric reactive carbon. Yet, much of this deposited organic carbon cannot be accounted for using traditional gas-phase deposition algorithms used in regional air quality models, signifying underrepresented, but influential, chemical-physical surface properties and processes. Furthermore, these fluxes represent a major unaccounted contribution of reactive carbon to downwind freshwater ecosystems that outweigh terrestrial sources, necessitating the inclusion of dry deposition in aquatic carbon balances and models.