DocTrack: A Visually-Rich Document Dataset Really Aligned with Human Eye Movement for Machine Reading

The use of visually-rich documents (VRDs) in various fields has created a demand for Document AI models that can read and comprehend documents like humans, which requires the overcoming of technical, linguistic, and cognitive barriers. Unfortunately, the lack of appropriate datasets has significantly hindered advancements in the field. To address this issue, we introduce \textsc{DocTrack}, a VRD dataset really aligned with human eye-movement information using eye-tracking technology. This dataset can be used to investigate the challenges mentioned above. Additionally, we explore the impact of human reading order on document understanding tasks and examine what would happen if a machine reads in the same order as a human. Our results suggest that although Document AI models have made significant progress, they still have a long way to go before they can read VRDs as accurately, continuously, and flexibly as humans do. These findings have potential implications for future research and development of Document AI models. The data is available at \url{https://github.com/hint-lab/doctrack}.Comment: 14 pages, 8 figures, Accepted by Findings of EMNLP202

Aqua­bis(2-chloro­acetato-κO)(1,10-phenanthroline-κ2 N,N′)copper(II)

In the title complex, [Cu(C2H2ClO2)2(C12H8N2)(H2O)], the CuII ion is five-coordinated by two N atoms [Cu—N = 2.005 (2) and 2.029 (2) Å] from the 1,10-phenanthroline ligand, two O atoms [Cu—O = 1.943 (2)–1.966 (2) Å] from two 2-chloro­acetate ligands and one water mol­ecule [Cu—O = 2.253 (2) Å] in a distorted square-pyramidal geometry. The crystal structure exhibits inter­molecular O—H⋯O hydrogen bonds, short Cl⋯Cl contacts [3.334 (1) Å] and π–π inter­actions [centroid–centroid distance 3.621 (11) Å]

Methane Activations by Lanthanum Oxide Clusters

Density functional theory and coupled cluster theory were employed to study the activations of CH₄ by neutral lanthanum oxide clusters (LaO­(OH), La₂O₃, La₃O₄(OH), La₄O₆, La₆O₉) as models for the La₂O₃ catalysts for the oxidative coupling of methane (OCM) reaction. The physisorption energies (Δ<i>H</i>_298 K) of CH₄ on the lanthanum oxide clusters were predicted to be −4 to −3 kcal/mol at the CCSD­(T) level. CH₄ is activated by hydrogen transfer to one of the O sites on the lanthanum oxide clusters, and the energy barriers (Δ<i>E</i>_0 K) from the physisorption structures were calculated to be modest at ∼20 kcal/mol for La₂O₃ and ∼25 kcal/mol for the other clusters. This is accompanied by the formation of a La–CH₃ bond, whose bond dissociation energy (Δ<i>E</i>_0 K) was calculated to be 53 to 60 kcal/mol. CH₄ chemisorption is slightly exothermic on LaO­(OH) and La₂O₃, whereas it becomes increasingly endothermic for the larger lanthanum oxide clusters. The formation of the CH₃ radical was predicted to be substantially endothermic, by ∼50 kcal/mol for LaO­(OH) and La₂O₃ and 64 to 76 kcal/mol for La₃O₄(OH) and La₄O₆ (Δ<i>H</i>_298 K). Calculations on the activation of CH₄ by La₆O₉ with a higher coordination number for both the La and O sites than La₄O₆ yield an energy barrier slightly higher by <1 kcal/mol, suggesting that the effects of the coordination numbers on the reaction energetics are rather small. The energy barrier for hydrogen abstraction does not correlate well with the negative charge on the O site, and a linear relation between the energy barrier and the chemisorption energy was not found for all the lanthanum oxide clusters, which is attributed to the strong dependency of their correlation on the specific chemical environment of the reactive site. Cluster reaction energies, physisorption and chemisorption energies, energy barriers, and La–CH₃ bond energies calculated at the DFT level with the B3LYP and PBE functionals were compared with those calculated at the CCSD­(T) level showing that the B3LYP functional yields better cluster reaction energies, chemisorption energies, and energy barriers. Although the PBE functional yields better physisorption energies, the DFT results can deviate substantially from the CCSD­(T) values. Although the O^2– sites in these cluster models were predicted to be less reactive toward CH₄ than the O^– sites modeled by the nonstoichiometric La₂O_3.33(001) surface (Palmer, M. S. et al. <i>J. Am. Chem. Soc.</i> <b>2002</b>, <i>124</i>, 8452), they are more reactive than the O₂^2– site modeled on the stoichiometric La₂O₃(001) surface, which suggests the relevance of the lattice oxygen sites on the La₂O₃ catalyst surfaces in the OCM reaction

Role of Peroxides on La₂O₃ Catalysts in Oxidative Coupling of Methane

Density functional theory and coupled cluster theory [CCSD­(T)] calculations reveal an important pathway for the one-step CH₃OH formation upon CH₄ activation at the peroxide (O₂^2–) site of La₂O₃-based catalysts for the oxidative coupling of methane (OCM) reaction. Using modest-sized La₄O₇ and La₆O₁₀ clusters as catalyst models, two types of structures for the O₂^2– site were predicted, with the less stable structure (type <b>II</b>) more reactive with CH₄ than the more stable structure (type <b>I</b>). CH₄ activation at the O₂^2– site can always occur via the above pathway, and for the smaller La₂O₄ cluster and the type <b>I</b> structure of La₄O₇, an alternative pathway leading to La–CH₃ bond formation was also predicted, similar to that at the oxide (O^2–) site from our previous study. For the type <b>I</b> structure of La₄O₇, the energy barrier for La–CH₃ bond formation is lower than that for CH₃OH formation, but both are higher than that for CH₃OH formation for the type <b>II</b> structure of La₄O₇. The O₂^2– site was predicted to be much less reactive with CH₄ than the oxide (O^2–) site, and can lead to CH₃OH formation, which is considered as a side reaction. Thus, our calculations do not appear to support the central role previously proposed for the O₂^2– site for La₂O₃-based catalysts for the OCM reaction. However, considering the catalytic and redox nature of this reaction, both the O^2– and O₂^2– sites may still play important roles in the whole catalytic cycle

CO₂ Chemisorption and Its Effect on Methane Activation in La₂O₃‑Catalyzed Oxidative Coupling of Methane

Density functional theory and coupled cluster theory calculations were carried out to study the formation of the carbonate species on La₂O₃ catalyst using the cluster model and its effect on subsequent CH₄ activation. Physisorption and chemisorption energies as well as energy barriers for the reaction of CO₂ and La₂O₃ clusters, and the reaction of CH₄ with the CO₃^2– site on the resulting clusters, were predicted. Our calculations show that CO₂ chemisorption at the La³⁺–O^2– pair sites is thermodynamically and kinetically very favorable due to the strong basicity of the O^2– site on La₂O₃, which leads to the formation of the La³⁺–CO₃^2– pair sites. In addition, CH₄ activation at the La³⁺–CO₃^2– pair sites is similar to that at the La³⁺–O^2– pair sites, which results in the formation of the bicarbonate species and the La–CH₃ bond, although the La³⁺–CO₃^2– pair sites are much less reactive with CH₄ in terms of both thermodynamics and kinetics. Further thermodynamical calculations show that the CO₃^2– species in these clusters dissociate between 500 to 1250 K, with half of them completely dissociated at 873 K, consistent with the experimental observation. Our studies suggest that the CO₃^2– site is unlikely to be the active site in La₂O₃-catalyzed oxidative coupling of methane, and CO₂ as a major byproduct is likely to act as a poison to the La₂O₃-based catalysts especially at modest reaction temperature

High speed atomic force microscope lithography driven by electrostatic interaction

This letter paper describes a scanning probe lithography method for fabricating patterns of various nanoparticles on SiOx/Si substrate. The electrostatic interaction resulting from the charge separation caused by the friction between the atomic force microscope (AFM) tip and the substrate was utilized as the driving force for the deposition of nanoparticles. The nanoparticles loaded on the tip were transported onto the substrate as the AFM tip moved at a speed as high as hundreds of mu m/s. This method allows patterning functional inorganic nanoparticles with a deliberate control over the feature size and shape. (C) 2007 American Institute of Physics