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At least 1,171 records · Page 65

Pyrolyzed Parylene-N for in Vivo Electrochemical Detection of Neurotransmitters

Carbon electrodes are typically used for in vivo dopamine detection, and new types of electrodes and customized fabrication methods will facilitate new applications. Parylene is an insulator that can be deposited in a thin layer on a substrate and then pyrolyzed to carbon to enable its use as an electrode. However, pyrolyzed parylene has not been used for the real-time detection of neurochemicals by fast-scan cyclic voltammetry. In this work, we deposited thin layers of parylene-N (PN) on metal wires and then pyrolyzed them to carbon with high temperatures in a rapid thermal processor (RTP). Different masses of PN, 1, 6, and 12 g, were deposited to vary the thickness. RTP-PN (6 g) produced a 194 nm layer carbon thickness and had optimal electrochemical stability. Pyrolyzed parylene-N modified electrodes (PPNMEs) were characterized for electrochemical detection of dopamine, serotonin, and adenosine. Background-normalized currents at PPNMEs were about 2 times larger than those of carbon-fiber microelectrodes (CFMEs). Rich defect sites and oxygen functional groups promoted the neurochemical adsorption of cationic neurotransmitters. PPNMEs resisted fouling from serotonin polymer formation. PPNMEs were used in vivo to detect stimulated dopamine release and monitor spontaneous adenosine release. Pyrolyzed parylene is a sensitive and fouling-resistant thin-film carbon electrode that could be used in the future for making customized electrodes and devices.

25 ENERGY STORAGE↗

Stress-Tolerant Nanoporous Germanium Nanofibers for Long Cycle Life Lithium Storage with High Structural Stability

Nanowires (NWs) synthesized via chemical vapor deposition (CVD) process have demonstrated significant improvement in lithium storage performance along with their outstanding accommodation of large volume changes during charge/discharge process. Nevertheless, the NW electrodes have been only confined to research level due to the lack of scalability and severe side reactions by their high surface area. Here, we present nanoporous Ge nanofibers (NPGeNFs) having moderate nanoporosity via a combination of simple electrospinning and low energetic zincothermic reduction reaction. In contrast with the CVD assisted NW growth, our method provides high tunability of macro/microscopic morphologies such as a porosity, length, and diameter of the nanoscale 1D structures. Significantly, the customized NPGeNFs showed highly suppressed volume expansion less than 15% (for electrodes) after full lithation and excellent durability with high lithium storage performance over 500 cycles. Our approach in this work offers effective 1D nanostructuring with highly customized geometries and can be extended to other applications including optoelectronics, catalysis, and energy conversion.

1D nanostructures↗

Nonlocal Metasurfaces with Lithographically Defined Vertical Symmetry Breaking

Nonlocal metasurfaces have garnered significant interest for applications that require customized and enhanced light–matter interactions in a flat form factor. These metasurfaces are distinctive for their ability to systematically control some of the fundamental properties of optical resonances by manipulating the in-plane symmetry of the lattice. Recent theoretical works have suggested that engineering the symmetry of a metasurface not just within the plane of the metasurface but also in the vertical or out-of-plane direction enables improved control of additional fundamental properties, especially chirality. However, standard nanofabrication processes cannot readily support elaborate vertical symmetry breaking such as nanostructure heights or slopes that deliberately vary across the footprint of a metasurface. Here, in this work, we experimentally demonstrate a scalable method to lithographically define the vertical symmetry of nonlocal metasurfaces by selectively eroding the etch mask during the etch process. Moreover, as the etch mask erosion rates depend on the in-plane size of individual nanostructures, we introduce and experimentally demonstrate a compatible design framework that enables versatile control over the properties of optical resonances. The results hold promise for chiral nonlocal metasurfaces with highly customized behavior.

metamaterial↗

An X-ray and Neutron Scattering Study of the Formation of Core-Shell Type Polyoxometalates

A typical type of core-shell polyoxometalates can be obtained through the Keggin-type polyoxometalatetemplated growth of a layer of spherical shell structure of {Mo72Fe30}. Small angle X-ray scattering is used to study the structural features and stability of the core-shell structures in aqueous solutions. Timeresolved small angle X-ray scattering is applied to monitor the synthetic reactions and a three-stage formation mechanism is proposed to describe the synthesis of the core-shell polyoxometalates based on the monitoring results. New protocols have been developed by fitting the X-ray data with customed physical models, which provide more convincing, objective, and completed data interpretation. Quasielastic and inelastic neutron scattering are used to probe the dynamics of water molecules in the core-shell structures and two different types of water molecules, the confined and structured water, are observed. These water molecules play an important role in bridging core and shell structures and stabilizing the cluster structures.

Yin, Panchao↗

Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO3 Perovskites

Strain is known to greatly influence low temperature oxygen electro catalysis on noble metal films, leading to significant enhancements in bifunctional activity essential for fuel cells and Metal-air batteries. However, its catalytic impact on transition-metal oxide thin films, such as perovskites, is not widely understood. Here, we epitaxially strain the conducting perovskite LaNiO3 to systematically determine its influence on both the oxygen reduction and oxygen evolution reaction. Uniquely, we found that compressive strain could significantly enhance both reactions, yielding a bifunctional catalyst that surpasses the performance of noble metals' such as Pt. We attribute the improved bifunctionality to strain induced splitting of the e(g) Orbitals, which can customize orbital asymmetry at the surface. Analogous to strain induced shifts in the d-band center of noble metals relative to the Fermi level, :such splitting can dramatically affect catalytic activity in this perovskite and other potentially more active Oxides.

Petrie, Jonathan R.↗

Customizable Aperture Geometry in Metal–Organic Frameworks for Kinetic Hydrocarbon Separation

Precise control of aperture dimensions is crucial in adsorptive separations of hydrocarbons, as it directly affects key parameters such as selectivity, capacity, diffusion, and recyclability. The development of metal–organic frameworks (MOFs) has enabled the fine-tuning of local pore environments to address important hydrocarbon separations. However, customizing the aperture geometry to tune the kinetic separation performance remains challenging. Here, we deploy a mixed-linker synthesis strategy, combining long and short linkers on fcu net Zr-MOFs with equilateral triangular apertures to construct isoreticular multivariate MOFs, NU-415 and NU-416, with tailored isosceles triangular apertures suitable for the separation of hexane isomers. Sorption, liquid batch separation, and X-ray diffraction measurements demonstrate significantly improved selectivity, capacity, stability, and recyclability of NU-415 and NU-416 compared with Zr-muconate and MOF-801. Notably, both NU-415 and NU-416 achieve uptake capacities of 2.2 mmol g –1 in 1 min with an n-hexane to 2,2-dimethylbutane selectivity over 200 in an equimolar ternary mixture at ambient conditions, comparable to leading reported materials. Mechanistic studies confirm that separation performance is predominantly governed by significant kinetic differences rather than by thermodynamics. Furthermore, the successful customization of aperture geometry not only enables superior linear to monobranched hexane selectivity in NU-415 but also demonstrates the mixed-linker synthesis strategy as a promising solution for precise and predictable pore architecture control in MOFs.

Adsorption↗

Topological superconductivity in skyrmion lattices

Atomic manipulation and interface engineering techniques have provided an intriguing approach to custom-designing topological superconductors and the ensuing Majorana zero modes, representing a paradigm for the realization of topological quantum computing and topology-based devices. Magnet-superconductor hybrid (MSH) systems have proven to be experimentally suitable to engineer topological superconductivity through the control of both the complex structure of its magnetic layer and the interface properties of the superconducting surface. Here, we demonstrate that two-dimensional MSH systems containing a magnetic skyrmion lattice provide an unprecedented ability to control the emergence of topological phases. By changing the skyrmion radius, which can be achieved experimentally through an external magnetic field, one can tune between different topological superconducting phases, allowing one to explore their unique properties and the transitions between them. In these MSH systems, Josephson scanning tunneling spectroscopy spatially visualizes one of the most crucial aspects underlying the emergence of topological superconductivity, the spatial structure of the induced spin–triplet correlations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Community Solar Reaches Adopters Underserved by Rooftop Solar

Community solar, a business model where multiple customers buy output from shared solar systems, has expanded solar access among multifamily housing occupants, renters, and low-income households. Policies to enable community solar could be expanded and benefits of access augmented through targeted measures to support community solar adoption in underserved communities.

community solar↗

Adaptive optical correction for in vivo two-photon fluorescence microscopy with neural fields

Adaptive optics restore ideal imaging performance in complex samples by measuring and correcting optical aberrations but often require custom-built microscopes with carefully aligned wavefront sensing/shaping devices and can be susceptible to sample motion. Here we describe NeAT, a computational framework using neural fields for adaptive optics two-photon fluorescence microscopy. NeAT estimates wavefront aberration and recovers sample structure from a 3D image stack without requiring external datasets for training. Incorporating motion correction in learning and correcting conjugation errors commonly found in commercial microscopes, NeAT is designed for deployment in biological laboratories for in vivo imaging. We validate NeAT’s performance using a custom-built microscope with a wavefront sensor under varying signal-to-noise ratios, aberration and motion conditions. With a commercial microscope, we demonstrate real-time aberration correction for in vivo morphological and functional imaging in the living mouse brain, with NeAT improving the signal and accuracy of glutamate and calcium imaging of synapses and neurons.

Kang, Iksung↗

Buildings Sector Scenarios: Demand-side data to support energy system planning in the United States

The US energy system is in a period of high uncertainty about load growth, its implications for the energy generation mix, and downstream impacts on customer energy costs. In this context, there is a need for comprehensive, credible, and readily-customized projections of energy demand to ensure that planning decisions account for end-use management opportunities to improve system reliability and affordability. Here we introduce the Buildings Sector Scenarios (BSS) dataset, which includes a benchmark suite of such projections for the buildings sector — a key source of energy consumption, peak electricity demand, and consumer energy expenditures. The dataset contains projections through 2050 covering the contiguous United States (CONUS) resolved down to the county, hourly level by sector and end use for electricity demand and to the state, annual level by sector and end use for non-electric fuels. We summarize the BSS analysis workflow and the tools and datasets that support it, document key BSS scenario inputs and modeling assumptions, and outline BSS scenario outputs. We assess the technical quality of the dataset against historical surveys and projected estimates of buildings sector demand. Finally, we provide guidance on how stakeholders can access, use, and reproduce the dataset, and/or create new scenarios to explore their own analysis questions.

Langevin, Jared↗

Image processing pipeline for AI-driven nanoparticle megalibrary characterization

Recent innovations have made it possible to produce megalibraries, millions of structurally and compositionally distinct nanoparticles on a chip. These megalibraries yield vast volumes of data that are impossible to analyze manually, necessitating the development of automated tools. In previous work, we created a binary classification machine learning model to select quality nanoparticle images for downstream analysis. In this work, we show that adding a custom image processing step before training can produce significantly higher-performing models in a fraction of the time and make them more robust to different image noise levels and microscope acquisition settings. The image processing pipeline proposed here effectively cleans raw nanoparticle images, enhances key features, and allows us to use much lower resolution images and simpler neural network model architectures. These features result in higher performance and significant cost savings. Experiments demonstrate superior performance relative to baseline, including an 18.2% improvement in recall and a 13.1% increase in accuracy. Given the high cost of downstream analysis, it is critical to minimize false positives, and our best-performing model reaches a precision of 95.9% and a weighted F-score of 95.1% on an unseen test set. Additionally, model training time is reduced from hours to less than a minute. We also show that, using this custom image processing pipeline, model performance is significantly improved at lower pixel resolutions compared to downsizing alone. We expect that adopting this pipeline for AI-driven automated nanoparticle characterization will allow researchers to rapidly and accurately analyze much greater volumes of data, thereby accelerating materials discovery.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Understanding ligand effects in gold clusters using mass spectrometry

This review summarizes recent research on the influence of phosphine ligands on the size, stability, and reactivity of gold clusters synthesized in solution. Sub-nanometer clusters exhibit size- and composition-dependent properties that are unique from those of larger nanoparticles. The highly tunable properties of clusters and their high surface-to-volume ratio make them promising candidates for a variety of technological applications. However, because “each-atom-counts” toward defining cluster properties it is critically important to develop robust synthesis methods to efficiently prepare clusters of predetermined size. For decades phosphines have been known to direct the size-selected synthesis of gold clusters. Despite the preparation of numerous species it is still not understood how different functional groups at phosphine centers affect the size and properties of gold clusters. Using electrospray ionization mass spectrometry (ESI-MS) it is possible to characterize the effect of ligand substitution on the distribution of clusters formed in solution at defined reaction conditions. In addition, ligand exchange reactions on preformed clusters may be monitored using ESI-MS. Collision induced dissociation (CID) may also be employed to obtain qualitative insight into the fragmentation of mixed ligand clusters and the relative binding energies of differently substituted phosphines. Quantitative ligand binding energies and cluster stability may be determined employing surface induced dissociation (SID) in a custom-built Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). Rice-Ramsperger-Kassel-Marcus (RRKM) based modeling of the SID data allows dissociation energies and entropy values to be extracted that may be compared with the results of high-level theoretical calculations. The charge reduction and reactivity of atomically precise gold clusters, including partially ligated species generated in the gas-phase by in source CID, on well-defined surfaces may be explored using ion soft landing (SL) in a custom-built instrument combined with in situ time of flight secondary ion mass spectrometry (TOF-SIMS). Jointly, this multipronged experimental approach allows characterization of the full spectrum of relevant phenomena including cluster synthesis, ligand exchange, thermochemistry, surface immobilization, and reactivity. The fundamental insights obtained from this work will facilitate the directed synthesis of gold clusters with predetermined size and properties for specific applications.

Environmental Molecular Sciences Laboratory↗

Direct observation of ice nucleation events on individual atmospheric particles

Heterogeneous ice nucleation is a physical chemistry process of critical relevance to a range of topics in the fundamental and applied sciences and technologies. Heterogeneous ice nucleation remains insufficiently understood, partially due to the lack of experimental methods capable of obtaining in situ microscopic details of ice formation over nucleating substrates or particles. Here, we present microscopic observations of ice nucleation events on kaolinite particles at the nanoscale and demonstrate the capability of direct tracking and micro-spectroscopic characterization of individual ice nucleating particles (INPs) in an authentic atmospheric sample. Furthermore, this approach utilizes a custom-built ice nucleation cell, interfaced with an Environmental Scanning Electron Microscope (IN-ESEM platform) operated at temperatures and relative humidities relevant for heterogeneous ice nucleation. The IN-ESEM platform allows dynamic observations of individual ice formation events over particles in isobaric and isothermal experiments. Isothermal experiments on individual kaolinite particles demonstrate that ice crystals preferably nucleate at the edges of the stacked kaolinite platelets, rather than on their basal planes. Finally, these experimental observations of the location of ice nucleation provide direct information for further theoretical chemistry predictions of ice formation on kaolinite.

54 ENVIRONMENTAL SCIENCES↗

Nanomorphology of eco-friendly colloidal inks, relating non-fullerene acceptor surface energy to structure formation

Nanoengineered, eco-friendly, solution-processable electroactive materials are in demand for the growing field of printed electronics, and these material requirements can be achieved by the development of waterborne colloidal dispersions. Functionality in these composite materials can be tuned by thermodynamically modifying the material nanomorphology, often by creation of kinetically stabilized aqueous nanoparticle dispersions. In this work we demonstrate that the internal structure of organic nanoparticles is controlled by the surface energy difference between the polymeric donor material and the non-fullerene acceptor (NFA) material. Nanoparticles of the following donor–acceptor combinations, suitable for printed organic photovoltaics, have been synthesized: TQ1:N2200, TQ1:PNDIT10, P3HT:N2200, P3HT:o-IDTBR and P3HT:eh-IDTBR. Advanced synchrotron-based X-ray spectroscopy and microscopy are used to correlate the formation of core–shell nanoparticle morphology to the material surface energy. We subsequently present a viable avenue for customizing the blended nanoparticle structure into (i) core–shell, (ii) molecularly intermixed, or (iii) inverted shell–core structures. Our results showed that TQ1:PNDIT10 and P3HT:o-IDTBR nanoparticles were comprised of a donor-rich shell and an NFA-rich core, however, interestingly we show a reversal to the inverse NFA shell/donor core structure for TQ1:N2200, P3HT:N2200 and P3HT:eh-IDTBR nanoparticles, driven by the low surface energy of N2200 (23.7 mJ m –2 ) and eh-IDTBR (18.3 mJ m –2 ). This article is the first report of a flipped nanoparticle core–shell morphology comprising an NFA-rich shell for the miniemulsion synthesis route. The composition of the shells and cores was able to be controlled by the differential mismatch in the surface energy of the donor and acceptor materials, with ΔG surface > 0, ΔG surface = 0, and ΔG surface < 0 for acceptor core–donor shell, molecularly intermixed, and acceptor shell–donor core, respectively. Accordingly, we introduce an entirely overlooked new figure of merit (FoM) for customizing nanoparticulate colloidal inks: tunable surface energy of non-fullerene-based semiconductors. Finally, the establishment of this FoM opens up electroactive material design to a wide range of functional printing applications with varying device and ink structure requirements, thereby reshaping the nanoengineering toolkit for waterborne colloidal dispersions and hence printed electronics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Day-ahead continuous double auction-based peer-to-peer energy trading platform incorporating trading losses and network utilisation fee

Integration of distributed energy resources, such as photovoltaic solar (PV), introduces new opportunities to establish local energy market frameworks to improve renewable energy utilisation in residential sectors. Such peer-to-peer (P2P) energy trading refers to a local market structure where customers (and prosumers) interact to share excess PV generation to enhance the individual and community social welfare. In this work, a day-ahead continuous double auction (CDA)-based P2P market structure considering network losses and network utilisation fees was designed. Day-ahead PV energy is modelled using fractional integral polynomials and the output is forecasted using an autoregressive integrated moving average model for each market interval. Based on the customer load and excess PV energy, the CDA market is cleared using a bid/ask matching mechanism. The performance of the P2P market was evaluated by computing different welfare metrics while analysing the effect of network constraints. The results show that the designed CDA-based P2P market structure increases the social welfare of all participants by an average of 17.75% compared to the baseline for the presented cases. Moreover, the impact of the forecasting error between the day-ahead and real-time market was also quantified.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Knowledge management: Role of the the Radiation Safety Information Computational Center (RSICC)

The Radiation Safety Information Computational Center (RSICC) at Oak Ridge National Laboratory (ORNL) is an information analysis center that collects, archives, evaluates, synthesizes and distributes information, data and codes that are used in various nuclear technology applications. RSICC retains more than 2,000 software packages that have been provided by code developers from various federal and international agencies. RSICC’s customers (scientists, engineers, and students from around the world) obtain access to such computing codes (source and/or executable versions) and processed nuclear data files to promote on-going research, to ensure nuclear and radiological safety, and to advance nuclear technology. The role of such information analysis centers is critical for supporting and sustaining nuclear education and training programs both domestically and internationally, as the majority of RSICC’s customers are students attending U.S. universities. Additionally, RSICC operates a secure CLOUD computing system to provide access to sensitive export-controlled modeling and simulation (M&S) tools that support both domestic and international activities. This presentation will provide a general review of RSICC’s activities, services, and systems that support knowledge management and education and training in the nuclear field.

Valentine, Timothy↗

Quantifying Hydraulic and Water Quality Uncertainty to Inform Sampling of Drinking Water Distribution Systems

Sampling of drinking water distribution systems is performed to ensure good water quality and protect public health. Sampling also satisfies regulatory requirements and is done to respond to customer complaints or emergency situations. Water distribution system modeling techniques can be used to plan and inform sampling strategies. However, a high degree of accuracy and confidence in the hydraulic and water quality models is required to support real-time response. One source of error in these models is related to uncertainty in model input parameters. Effective characterization of these uncertainties and their effect on contaminant transport during a contamination incident is critical for providing confidence estimates in model-based design and evaluation of different sampling strategies. In this paper, the effects of uncertainty in customer demand, isolation valve status, bulk reaction rate coefficient, contaminant injection location, start time, duration, and rate on the size and location of the contaminant plume are quantified for two example water distribution systems. Results show that the most important parameter was the injection location. The size of the plume was also affected by the reaction rate coefficient, injection rate, and injection duration, whereas the exact location of the plume was additionally affected by the isolation valve status. As a result, uncertainty quantification provides a more complete picture of how contaminants move within a water distribution system and more information when using modeling results to select sampling locations.

54 ENVIRONMENTAL SCIENCES↗

Automated management of radioactive sources in Saudi Arabia

For usage of radioactive substances, any facility has to register and take license from relevant authority of the country in which such facility is operating. In the Kingdom of Saudi Arabia (KSA), the authority for managing radioactive sources and providing licenses to organizations for its usage is the National Center of Radiation Protection (NCRP). This paper describes the system that automates registration and licensing process of the National Center of Radiation Protection. To provide 24×7 accesses to all the customers of NCRP, system is developed as web-based application that provide facility to online register, request license, renew license, check request status, view historical data and reports etc. and other features are provided as Electronic Services that would be accessible to users via internet. The system also was designed to streamline and optimize internal operations of NCRP besides providing ease of access to its customers by implementing a defined workflow through which every registration and license request will be routed. In addition to manual payment option, the system would also be integrated with SADAD (online payment system) that will avoid lengthy and cumbersome procedures associated with manual payment mechanism. Using SADAD payment option license fee could be paid through internet/ATM machine or branch of any designated bank, Payment will be instantly notified to NCRP hence delay in funds transfer and verification of invoice could be avoided, SADAD integration is discussed later in the document.

07 ISOTOPE AND RADIATION SOURCES↗