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At least 37 records · Page 2

Atomically Dispersed Dual‐Metal Site Catalysts for Enhanced CO 2 Reduction: Mechanistic Insight into Active Site Structures

Abstract Carbon‐supported nitrogen‐coordinated single‐metal site catalysts (i.e., M−N−C, M: Fe, Co, or Ni) are active for the electrochemical CO 2 reduction reaction (CO 2 RR) to CO. Further improving their intrinsic activity and selectivity by tuning their N−M bond structures and coordination is limited. Herein, we expand the coordination environments of M−N−C catalysts by designing dual‐metal active sites. The Ni‐Fe catalyst exhibited the most efficient CO2RR activity and promising stability compared to other combinations. Advanced structural characterization and theoretical prediction suggest that the most active N‐coordinated dual‐metal site configurations are 2N‐bridged (Fe‐Ni)N 6 , in which FeN 4 and NiN 4 moieties are shared with two N atoms. Two metals (i.e., Fe and Ni) in the dual‐metal site likely generate a synergy to enable more optimal *COOH adsorption and *CO desorption than single‐metal sites (FeN 4 or NiN 4 ) with improved intrinsic catalytic activity and selectivity.

Li, Yi↗

Uncovering the True Active Sites in Ni–N–C Catalysts for CO 2 Electroreduction

Understanding and designing active sites in single-atom catalysts (SACs) requires going beyond static models to capture their dynamic evolution under realistic electrochemical conditions. Here, in this work, we develop an integrated theoretical framework that accounts for operational conditions, by combining grand canonical density functional theory (GC-DFT) with machine-learning-accelerated sampling, to uncover structure–activity–stability relationships in Ni–N–C SACs for the CO 2 reduction reaction (CO 2 RR). A library of NiN x C 4–x (x = 0–4) motifs─representing coordination defects likely formed during high-temperature synthesis─was systematically evaluated. Under working conditions, these sites were found to undergo hydrogenation, and NiN 3 C 1_ H 1 was identified as the most probable active site. At reducing potentials, hydrogen adsorbs spontaneously at C–Ni bridge sites rather than Ni top sites, while subsurface hydrogen facilitates bent CO 2 adsorption crucial for activation. High CO 2 RR selectivity toward CO arises from site separation: Ni centers drive CO2RR, while the hydrogen evolution reaction (HER) occurs at the C–Ni bridge or N sites and from thermodynamic suppression of HER at moderate hydrogen coverage. At more negative potentials, a shift in the CO 2 RR rate-determining process (RDP) and Ni out-of-surface displacement induced by coadsorption of H and H 2 O jointly reduce activity and selectivity. Thus, both the high CO2RR selectivity of Ni–N–C catalysts and its reversal with more negative potentials can be rationalized by accounting for hydrogenated surfaces. This highlights the necessity of modeling realistic; in situ conditions. This framework provides generalizable insights into the dynamic behavior of active sites in SACs, offering guidance for the rational design of active and robust catalysts for a wide range of electrochemical reactions.

25 ENERGY STORAGE↗

Spatial and temporal trends and variabilities of hailstones in the United States Northern Great Plains and their possible attributions

Following on our study of hail for the Southern Great Plains (SGP), we investigated the spatial and temporal hail trends and variabilities for the Northern Great Plains (NGP) and the contributing factors for summer seasons (June–August) over 2004–2016 using two independent hail datasets. Both severe hail (1 < diameter = 2 inches) and significant severe hail (diameter > 2 inches) were examined and similar results were obtained. The hailstones in the NGP demonstrate a large interannual variability, with an overall increasing trend over 2004–2016. Spatially, the positive trend is mainly located in the western part of South Dakota and North Dakota. We find the three major dynamical factors that most likely contribute to the hail interannual variability in the NGP are the El Niño-Southern Oscillation (ENSO), North Atlantic subtropical high (NASH), and low-level jet (LLJ). With a thermodynamical variable integrated water vapor transport (IVT) that is strongly controlled by LLJ, the four factors can explain 76% of the hail interannual variability from the hail reports based on the multivariate linear regression. Hail occurrences are 73% higher during the cold phase of ENSO (La Nin~a) than the warm phase of ENSO (El Nin~o). When the NASH has a larger northwestward expansion or stronger intensity, more hail occurs over the NGP, because the increases of latitudinal gradient of pressure leads to a stronger LLJ. Interestingly, the important factors impacting hail interannual variability over the NGP are quite different from those for the SGP, except ENSO.

Jeong, Jong-Hoon↗

Computational Discovery of Active and Selective Metal‐Nitrogen‐Graphene Catalysts for Electrooxidation of Water to H 2 O 2

A direct electrosynthesis of H 2 O 2 from either O 2 or H 2 O is an attractive strategy to replace the energy-intensive industrial anthraquinone process. Two-electron water oxidation reaction (2e-WOR) offers several advantages over the oxygen reduction reaction such as better mass transfer due to the absence of gas-phase reactants. However, 2e-WOR is a more challenging and less studied process with only a handful of metal oxides exhibiting reasonable activity/selectivity properties. Herein, we employ density-functional-theory calculations to screen a variety of metal-nitrogen-graphene structures for 2e-WOR. As a consequence of scaling between the adsorption energies of reaction intermediates, we determine a linear relation between selectivities for the first and second reaction steps of 2e-WOR, viz. that if selectivity toward adsorbed OH is improved, then selectivity toward H 2 O 2 at the subsequent step is decreased. We also find that selectivity and activity are linearly scaled in such a way that a higher activity (i.e., a lower overpotential) leads to a lower selectivity for the H 2 O 2 formation step. Based on the obtained results several chemistries, e.g., containing NiN x -C moieties, are predicted to rival the best-performing metal oxides such as ZnO and CaSnO 3 in terms of combination of their activity/selectivity characteristics for 2e-WOR.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Atomically Dispersed Single Ni Site Catalysts for Nitrogen Reduction toward Electrochemical Ammonia Synthesis Using N 2 and H 2 O

Ammonia (NH 3 ) electrosynthesis gains significant attention as NH 3 is essentially important for fertilizer production and fuel utilization. However, electrochemical nitrogen reduction reaction (NRR) remains a great challenge because of low activity and poor selectivity. Herein, a new class of atomically dispersed Ni site electrocatalyst is reported, which exhibits the optimal NH 3 yield of 115 µg cm -2 h -1 at –0.8 V versus reversible hydrogen electrode (RHE) under neutral conditions. High faradic efficiency of 21 ± 1.9% is achieved at -0.2 V versus RHE under alkaline conditions, although the ammonia yield is lower. The Ni sites are stabilized with nitrogen, which is verified by advanced X-ray absorption spectroscopy and electron microscopy. Density functional theory calculations provide insightful understanding on the possible structure of active sites, relevant reaction pathways, and confirm that the Ni-N 3 sites are responsible for the experimentally observed activity and selectivity. Extensive controls strongly suggest that the atomically dispersed NiN 3 site-rich catalyst provides more intrinsically active sites than those in N-doped carbon, instead of possible environmental contamination. Overall, this work further indicates that single-metal site catalysts with optimal nitrogen coordination is very promising for NRR and indeed improves the scaling relationship of transition metals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Nanodevices engineering and spin transport properties of MnBi2Te4 monolayer

Abstract Two-dimensional (2D) magnetic materials are essential for the development of the next-generation spintronic technologies. Recently, layered van der Waals (vdW) compound MnBi 2 Te 4 (MBT) has attracted great interest, and its 2D structure has been reported to host coexisting magnetism and topology. Here, we design several conceptual nanodevices based on MBT monolayer (MBT-ML) and reveal their spin-dependent transport properties by means of the first-principles calculations. The pn -junction diodes and sub-3-nm pin -junction field-effect transistors (FETs) show a strong rectifying effect and a spin filtering effect, with an ideality factor n close to 1 even at a reasonably high temperature. In addition, the pip - and nin -junction FETs give an interesting negative differential resistive (NDR) effect. The gate voltages can tune currents through these FETs in a large range. Furthermore, the MBT-ML has a strong response to light. Our results uncover the multifunctional nature of MBT-ML, pave the road for its applications in diverse next-generation semiconductor spin electric devices.

Chemistry↗

The putative transporter MtUMAMIT14 participates in nodule formation in Medicago truncatula

Transport systems are crucial in many plant processes, including plant–microbe interactions. Nodule formation and function in legumes involve the expression and regulation of multiple transport proteins, and many are still uncharacterized, particularly for nitrogen transport. Amino acids originating from the nitrogen-fixing process are an essential form of nitrogen for legumes. This work evaluates the role of MtN21 (henceforth MtUMAMIT14), a putative transport system from the MtN21/EamA-like/UMAMIT family, in nodule formation and nitrogen fixation in Medicago truncatula. To dissect this transporter’s role, we assessed the expression of MtUMAMIT14 using GUS staining, localized the corresponding protein in M. truncatula root and tobacco leaf cells, and investigated two independent MtUMAMIT14 mutant lines. Our results indicate that MtUMAMIT14 is localized in endosomal structures and is expressed in both the infection zone and interzone of nodules. Comparison of mutant and wild-type M. truncatula indicates MtUMAMIT14, the expression of which is dependent on the presence of NIN, DNF1, and DNF2, plays a role in nodule formation and nitrogen-fixation. While the function of the transporter is still unclear, our results connect root nodule nitrogen fixation in legumes with the UMAMIT family.

58 GEOSCIENCES↗

Single and dual metal atom catalysts for enhanced singlet oxygen generation and oxygen reduction reaction

We demonstrate rational design of graphene-supported single and dual metal atom catalysts (SACs and DACs) for photocatalytic applications, such as singlet oxygen ( 1 O 2 ) sensitization and H 2 O 2 production. Here we combine density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations with experimental verifications. We found a synergistic effect between triplet sensitization and triplet–triplet (Dexter) energy transfer; both play a role in the photocatalytic activity through the volcano plot of 3d transition metal SACs. More specifically, FeN 4 -SAC exhibits a low ISC energy gap (ΔE ISC ) of 0.039 eV, compared with 0.108 eV for FeNiN8-DACs, both possessing a high Bader charge transfer of 0.366 e- and 0.405 e-, respectively. Guided by these computational results, we synthesized a series of SACs and a DAC and confirmed their structures with scanning transmission electron microscopy (STEM) along with the X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). We then confirm their band structures with low-energy inverse photoemission spectroscopy (LEIPS) and UV-vis-NIR. Subsequently, we synthesized the catalysts for the photooxygenation of anthracene and two-electron oxygen reduction reaction (ORR) to measure their photocatalytic activity. We found that H 2 O 2 production through the two-electron ORR competes with the 1 O 2 generation through Dexter energy transfer. FeN 4 -SAC demonstrates a high photooxygenation conversion of 86% and a high 1 O 2 quantum yield of 1.04, obtained from electron spin resonance (ESR) spectroscopy, with low H 2 O 2 production. In contrast, NiN 4 -SAC exhibits a low 1 O 2 generation and a high H 2 O 2 production mainly because of the high Gibbs free energy of the OOH* intermediate. In conclusion, this work proposes an effective DFT-guided strategy for designing SACs and DACs for various photocatalytic applications.

36 MATERIALS SCIENCE↗

Materials Data on Li6V3P8O29 by Materials Project

Li6V3P8O29 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are twelve inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.94–2.18 Å. In the second Li1+ site, Li1+ is bonded in a distorted see-saw-like geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 2.01–2.08 Å. In the third Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 2.01–2.10 Å. In the fourth Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 tetrahedra that share a cornercorner with one LiO4 tetrahedra, corners with four PO4 tetrahedra, and an edgeedge with one VO6 octahedra. There are a spread of Li–O bond distances ranging from 1.96–2.24 Å. In the fifth Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.94–2.28 Å. In the sixth Li1+ site, Li1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 2.01–2.22 Å. In the seventh Li1+ site, Li1+ is bonded in a distorted see-saw-like geometry to four O2- atoms. There are a spread of Li–O bond distances ranging from 1.95–2.11 Å. In the eighth Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with three VO6 octahedra and corners with four PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 67–70°. There are a spread of Li–O bond distances ranging from 1.85–2.28 Å. In the ninth Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 tetrahedra that share corners with four PO4 tetrahedra and an edgeedge with one VO6 octahedra. There are a spread of Li–O bond distances ranging from 2.00–2.17 Å. In the tenth Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 tetrahedra that share a cornercorner with one LiO4 tetrahedra, corners with four PO4 tetrahedra, and an edgeedge with one VO6 octahedra. There are a spread of Li–O bond distances ranging from 1.97–2.12 Å. In the eleventh Li1+ site, Li1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 1.99–2.58 Å. In the twelfth Li1+ site, Li1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Li–O bond distances ranging from 1.95–2.81 Å. There are six inequivalent V4+ sites. In the first V4+ site, V4+ is bonded to six O2- atoms to form VO6 octahedra that share a cornercorner with one LiO4 tetrahedra, corners with six PO4 tetrahedra, and an edgeedge with one LiO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.88–2.00 Å. In the second V4+ site, V4+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.87–2.05 Å. In the third V4+ site, V4+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.90–2.03 Å. In the fourth V4+ site, V4+ is bonded to six O2- atoms to form VO6 octahedra that share a cornercorner with one LiO4 tetrahedra and corners with six PO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.86–2.05 Å. In the fifth V4+ site, V4+ is bonded to six O2- atoms to form VO6 octahedra that share a cornercorner with one LiO4 tetrahedra, corners with six PO4 tetrahedra, and an edgeedge with one LiO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.86–1.99 Å. In the sixth V4+ site, V4+ is bonded to six O2- atoms to form VO6 octahedra that share corners with six PO4 tetrahedra and an edgeedge with one LiO4 tetrahedra. There are a spread of V–O bond distances ranging from 1.91–1.98 Å. There are sixteen inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra, a cornercorner with one LiO4 tetrahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 41–45°. There are a spread of P–O bond distances ranging from 1.51–1.61 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 35–42°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three VO6 octahedra and a cornercorner with one LiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 33–35°. There are a spread of P–O bond distances ranging from 1.49–1.58 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three VO6 octahedra. The corner-sharing octahedra tilt angles range from 36–38°. There are a spread of P–O bond distances ranging from 1.50–1.58 Å. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra, a cornercorner with one PO4 tetrahedra, and corners with two LiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–43°. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the seventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–47°. There are a spread of P–O bond distances ranging from 1.52–1.62 Å. In the eighth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra, a cornercorner with one LiO4 tetrahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–41°. There are a spread of P–O bond distances ranging from 1.52–1.61 Å. In the ninth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra, a cornercorner with one PO4 tetrahedra, and corners with two LiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 45–46°. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the tenth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra, a cornercorner with one LiO4 tetrahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–39°. There are a spread of P–O bond distances ranging from 1.51–1.61 Å. In the eleventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra, a cornercorner with one LiO4 tetrahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 46–47°. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. In the twelfth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three VO6 octahedra and a cornercorner with one LiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 29–36°. There is one shorter (1.48 Å) and three longer (1.58 Å) P–O bond length. In the thirteenth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three VO6 octahedra and corners with two LiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 33–37°. There are a spread of P–O bond distances ranging from 1.50–1.57 Å. In the fourteenth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra, a cornercorner with one LiO4 tetrahedra, and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–48°. There are a spread of P–O bond distances ranging from 1.52–1.61 Å. In the fifteenth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 39–45°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the sixteenth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two VO6 octahedra, a cornercorner with one PO4 tetrahedra, and corners with three LiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 45–49°. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. There are fifty-eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Li1+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one V4+, and one P5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Li1+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+, one V4+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Li1+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one V4+, and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+, one V4+, and one P5+ atom. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+, one V4+, and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the fourteenth O2- site, O2- is bonded in a single-bond geometry to one P5+ atom. In the fifteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one V4+, and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+, one V4+, and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one V4+, and one P5+ atom. In the nineteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the twentieth O2- site, O2- is bonded in a 4-coordinate geometry to three Li1+ and one P5+ atom. In the twenty-first O2- site, O2- is bonded in a 3-coordinate geometry to two Li1+ and one P5+ atom. In the twenty-second O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the twenty-third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Li1+, one V4+, and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+, one V4+, and one P5+ atom. In the twenty-fifth O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the twenty-sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one V4+ and one P5+ atom. In the twenty-seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the twenty-eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Li1+ and one P5+ atom. In the twenty-nin

36 MATERIALS SCIENCE↗

Binary Complex Neural Network Acceleration on FPGA

Being able to learn from complex data with phase information is imperative for many signal processing applications. Today’s real-valued deep neural networks (DNNs) have shown efficiency in latent information analysis but fall short when applied to the complex domain. Deep complex networks (DCN) , in contrast, can learn from complex data, but have high computational costs; therefore, they cannot satisfy the instant decision making requirements of many deployable systems dealing with short observations or short signal bursts. Recent, Binarized Complex Neural Network (BCNN), which integrates DCNs with binarized neural networks (BNN), shows great potential in classifying complex data in real-time. In this paper, we propose a structural pruning based accelerator of BCNN, which is able to provide more than 5000 frames/s inference throughput on edge devices. The high performance comes from both the algorithm and hardware sides. On the algorithm side, we conduct structural pruning to the original BCNN models and obtain 20 × pruning rates with negligible accuracy loss; on the hardware side, we propose a novel 2D convolution operation accelerator for the binary complex neural network. Experimental results show that the proposed design works with over 90% utilization and is able to achieve the inference throughput of 5882 frames/s and 4938 frames/s for complex NIN-Net and ResNet-18 using CIFAR-10 dataset and Alveo U280 Board.

Peng, Hongwu↗

A Real2Sim Digital Twin Pipeline for Photorealistic Robot Simulation: Evaluating VLA Policy Deployment on a Bimanual Mobile Robot

Digital twins that are automatically constructed from robot sensor data offer a promising pathway for scalable Real2Sim and Sim2Real transfer. However, it remains an open question whether photorealistic reconstruction alone is sufficient to support reliable deployment of vision-language-action (VLA) policies. We present a generative-AI-assisted Real2Sim pipeline that generates simulation-ready digital twins from real-world RGB observations with minimal manual intervention. The pipeline uses prompted segmentation to isolate scene components and a generative 3D model to directly produce simulation assets, eliminating the need for traditional multi-view reconstruction or manual 3D modeling.\r\nTo evaluate simulation fidelity, we deploy and compare policies from two VLA models in both the real robot and the reconstructed\r\nsimulation under identical tasks and initial conditions. We compare joint-level action trajectories and analyze how divergence evolves over time in closed-loop execution. Although the reconstructed environments are visually accurate, we observe increasing trajectory divergence during closedloop operation. These results indicate that photorealistic reconstruction alone is insufficient to preserve closed-loop control behavior\r\nin VLA policies, particularly in contact-rich manipulation settings where small perceptual errors compound over time.

97 MATHEMATICS AND COMPUTING↗

Progress in Extending the High-Temperature Plasma Regime in the LHD

In this paper, we show the expansion of the high-temperature regime and related physical phenomena in the Large Helical Device (LHD). At the LHD, we have developed a high-temperature operational regime for both ion (T i ) and electron (T e ) temperatures through understanding the physical characteristics of high-temperature plasma, the enhancement of plasma heating, and the development of technical methods such as wall recycling control and impurity control. In particular, the formation of the ion internal transport barrier (i-ITB) and electron internal transport barrier (e-ITB) in the plasma core region is the key to improving plasma performance. In addition, the deuterium experiment that began in 2017 showed that, due to the isotope effect, the thermal transport of both ions and electrons is suppressed in deuterium plasma compared to light hydrogen plasma, and that a high central temperature can be achieved efficiently. Furthermore, the combination of neutral beam injection (NBI) and electron cyclotron heating (ECH) has extended the operating conditions that simultaneously maintain high T i and T e , and comprehensive research on plasma confinement characteristics with an eye to future fusion reactor conditions has progressed.

Large Helical Device↗

Enhancement of mid-/high-Z impurity transport by continuous Li-granule dropping in a stellarator plasma

An enhancement of core impurity transport is observed in high-density plasmas of the stellarator large helical device, heated by neutral beam injection, when continuous lithium (Li) granule dropping is performed. In the reported experiments, in which the tracer-encapsulated solid pellet is employed to inject trace amounts of titanium (Ti) and molybdenum (Mo) into the plasma core, confinement times for these impurities are seen to reduce significantly when Li dropping is applied, this reduction being more notable for Mo. To gain some initial insight into these observations, simulations are performed using the drift-kinetic transport code SFINCS for the Mo case. These simulations indicate that, while neoclassical transport prevails for the main plasma components (electrons, majority ions, and low-Z impurities), the classical contribution appears dominant for transporting Mo impurities. In summary, this work reports the first experimental observation of the degradation of mid-Z and high-Z impurity confinement induced by the continuous dropping of Li granules into a high-density stellarator plasma. In the case of the Mo impurity, simulations suggest that classical transport is the key mechanism underlying the enhanced impurity transport.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

High resolution measurements of core density collapse dynamics in LHD

The core density collapse (CDC) is an abrupt instability that degrades the performance of super dense core stellarator plasmas on the Large Helical Device (LHD). In LHD, CDCs have proved to be an operational limit in so-called outward-shifted configurations. New measurements with high time resolution Thomson scattering characterize dynamics of the instability in the core. The density profile is observed to collapse inwards, narrowing the density peak till the core itself collapses. A hot, radially localized feature is also observed in the electron temperature profile during the collapse and disappears within a few hundred microseconds of CDC onset.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Characterization of runaway electron impact on instrumented sacrificial limiters on DIII-D

Instrumented sacrificial limiter heads, both domed (proud) and flat (flush) are used in DIII-D runaway electron (RE) wall strikes to study the wall impact dynamics with high spatial and time resolution. The approximate structure of the RE wetted area and heating depth on the domed limiter heads were predicted qualitatively using orbit-tracking simulations, although a strong left–right asymmetry (about the magnetic field direction) was not captured well by the simulations. It is hypothesized that this difference is perhaps due to the local 3D magnetic field perturbation of the dome limiter head. The average kinetic energy K and pitch angle θ of REs striking the limiter head were estimated from the spatial distribution of local HXR emission and were estimated to be roughly K ≈ 4 MeV and θ ≈ 0.2 rad. These values are roughly consistent with in-plasma values estimated before the loss event, indicating that RE kinetic energy and pitch angle are not drastically altered when transporting to the wall. Large shot–shot variations (1–10 kJ) in energy deposition into the limiter head were observed and were explained by shot–shot variations in locked magneto-hydrodynamics mode toroidal phase. For the largest deposited energies (10 kJ), graphite material failure and explosive dust release was observed, and the depth of material failure at higher energy deposition was successfully reproduced using modelling of volumetric energy deposition and brittle failure. The presence of energetic (keV) level ion impact during the RE wall strike was confirmed by three different surface analysis techniques. The ratio of energetic ion to RE flux appears to be larger on flat surfaces within the RE wetted area, although the energetic ion flux and total energy flux due to energetic ions have not yet been quantified.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Particle collisionality in scaled kinetic plasma simulations

Kinetic plasma processes, such as magnetic reconnection, collisionless shocks, and turbulence, are fundamental to the dynamics of astrophysical and laboratory plasmas. Simulating these processes often requires particle-in-cell (PIC) methods, but the computational cost of fully kinetic simulations can necessitate the use of artificial parameters, such as a reduced speed of light and ion-to-electron mass ratio, to decrease expense. While these approximations can preserve overall dynamics under specific conditions, they introduce nontrivial impacts on particle collisionality that are not yet well understood. In this work, we develop a method to scale particle collisionality in simulations employing an artificial speed of light and/or an artificial ion-to-electron mass ratio. By introducing species-dependent scaling factors, we independently adjust inter- and intra-species collision rates to better replicate the collisional properties of the physical system. Our approach maintains the fidelity of electron and ion transport properties while preserving critical relaxation rates, such as energy exchange timescales, within the limits of weakly collisional plasma theory. Furthermore, we demonstrate the accuracy of this scaling method through benchmarking tests against theoretical relaxation rates and connecting to fluid theory, highlighting its ability to retain key transport properties. Existing collisional PIC implementations can be easily modified to include this scaling, which will enable deeper insights into the behavior of marginally collisional plasmas across various contexts.

Totorica, S. R. [Princeton Univ., NJ (United State↗

Formation of Inorganic Sulfate and Volatile Nonsulfated Products from Heterogeneous Hydroxyl Radical Oxidation of 2-Methyltetrol Sulfate Aerosols: Mechanisms and Atmospheric Implications

Chemical transformation of 2-methyltetrol sulfates (2-MTS), key isoprene-derived secondary organic aerosol (SOA) constituents, through heterogeneous hydroxyl radical ( • OH) oxidation can result in the formation of previously unidentified atmospheric organosulfates (OSs). However, detected OSs cannot fully account for the sulfur content released from reacted 2-MTS, indicating the existence of sulfur in forms other than OSs, such as inorganic sulfates. This work investigated the formation of inorganic sulfates through heterogeneous • OH oxidation of 2-MTS aerosols. Remarkably, high yields of inorganic sulfates, defined as the moles of inorganic sulfates produced per mole of reacted 2-MTS, were observed in the range from 0.48 ± 0.07 to 0.68 ± 0.07. These could be explained by the production of sulfate (SO 4 •- ) and sulfite (SO 3 •- ) radicals through the cleavage of C-O(S) and (C)O-S bonds, followed by aerosol-phase reactions. Additionally, non-sulfated products resulting from bond cleavage were likely volatile and evaporated into gas phase, as evidenced by observed aerosol mass loss (up to 25%) and concurrent size reduction upon oxidation. This investigation highlights the significant transformation of sulfur from its organic to inorganic forms during the heterogeneous oxidation of 2-MTS aerosols, potentially influencing the physicochemical properties and environmental impacts of isoprene-derived SOA.

54 ENVIRONMENTAL SCIENCES↗

Inorganic Sulfur Species Formed upon Heterogeneous OH Oxidation of Organosulfates: A Case Study of Methyl Sulfate

In this report recent studies reveal that organosulfates at the particle surface can be oxidized by gas-phase OH radicals with significant rates. Inorganic sulfur species, such as the bisulfate ion (HSO 4 - ) and sulfate ion (SO 4 2- ), can be formed upon these heterogeneous oxidation processes through the formation and subsequent reactions of sulfate radical anions (SO 4 •- ) in the particle phase. However, the amount of inorganic sulfur species produced in these heterogeneous oxidation reactions is not known. We investigate the heterogeneous OH oxidation of sodium methyl sulfate (CH 3 SO 4 Na), the smallest organosulfate detected in atmospheric particles, using an oxidation flow reactor at a relative humidity of 75%. We quantify the kinetics by measuring the decay of CH 3 SO 4 Na and the amount of HSO 4 - and SO 4 2- formed upon oxidation using ion chromatography. Kinetic measurements determine the heterogeneous OH reaction rate to be (5.72 ± 0.14) x 10 -13 cm 3 molecule -1 s -1 , with an effective OH uptake coefficient, γ eff , of 0.31 ± 0.06. The molar yield of inorganic sulfur species, defined as the total number of moles of HSO 4 - and SO 4 2- formed per mole of CH 3 SO 4 Na consumed upon oxidation, is found to be significant and has an average value of 0.62 ± 0.18 upon oxidation. A kinetic model is developed to describe the kinetics and inorganic sulfur species formation upon oxidation. Model simulations suggest that CH 3 SO 4 Na tends to decompose rapidly into formaldehyde and SO 4 •- , and the reaction of SO 4 •- with CH 3 SO 4 Na plays a significant role in both governing the kinetics and the formation of inorganic sulfur species.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗