66 research outputs found
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
AquaÂbis(2-chloroÂacetato-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-chloroÂacetate ligands and one water molÂecule [Cu—O = 2.253 (2) Å] in a distorted square-pyramidal geometry. The crystal structure exhibits interÂmolecular O—H⋯O hydrogen bonds, short Cl⋯Cl contacts [3.334 (1) Å] and π–π interÂactions [centroid–centroid distance 3.621 (11) Å]
Association of diet and outdoor time with inflammatory bowel disease: a multicenter case-control study using propensity matching analysis in China
ObjectiveTo investigate the association between dietary and some other environmental factors and the risk of inflammatory bowel diseases (IBD) in Chinese population.Materials and methodsA multicenter case-control study was conducted involving 11 hospitals across China. A total of 1,230 subjects were enrolled consecutively, and diet and environmental factor questionnaires were collected. IBD patients were matched with healthy controls (HC) using propensity-score matching (PSM) at a 1:1 ratio with a caliper value of 0.02. Multivariate conditional logistic regression analyses were performed to evaluate the associations between diet, environmental factors, and IBD.ResultsModerate alcohol and milk consumption, as well as daily intake of fresh fruit, were protective factors for both Crohn's disease (CD) and ulcerative colitis (UC). Conversely, the consumption of eggs and chocolate increased the risk of IBD. Outdoor time for more than 25% of the day was a protective factor only for CD. In eastern regions of China, CD patients had higher egg consumption and less outdoor time, while UC patients consumed more chocolate. IBD patients from urban areas or with higher per capita monthly income consumed more fruit, eggs, and chocolate.ConclusionsThis study reveals an association between specific foods, outdoor time, and the emergence of IBD in the Chinese population. The findings emphasize the importance of a balanced diet, sufficient outdoor time and activities, and tailored prevention strategies considering regional variations
Methane Activations by Lanthanum Oxide Clusters
Density
functional theory and coupled cluster theory were employed
to study the activations of CH<sub>4</sub> by neutral lanthanum oxide
clusters (LaOÂ(OH), La<sub>2</sub>O<sub>3</sub>, La<sub>3</sub>O<sub>4</sub>(OH), La<sub>4</sub>O<sub>6</sub>, La<sub>6</sub>O<sub>9</sub>) as models for the La<sub>2</sub>O<sub>3</sub> catalysts for the
oxidative coupling of methane (OCM) reaction. The physisorption energies
(Δ<i>H</i><sub>298 K</sub>) of CH<sub>4</sub> on the lanthanum oxide clusters were predicted to be −4 to
−3 kcal/mol at the CCSDÂ(T) level. CH<sub>4</sub> is activated
by hydrogen transfer to one of the O sites on the lanthanum oxide
clusters, and the energy barriers (Δ<i>E</i><sub>0 K</sub>) from the physisorption structures were calculated to be modest
at ∼20 kcal/mol for La<sub>2</sub>O<sub>3</sub> and ∼25
kcal/mol for the other clusters. This is accompanied by the formation
of a La–CH<sub>3</sub> bond, whose bond dissociation energy
(Δ<i>E</i><sub>0 K</sub>) was calculated to be
53 to 60 kcal/mol. CH<sub>4</sub> chemisorption is slightly exothermic
on LaOÂ(OH) and La<sub>2</sub>O<sub>3</sub>, whereas it becomes increasingly
endothermic for the larger lanthanum oxide clusters. The formation
of the CH<sub>3</sub> radical was predicted to be substantially endothermic,
by ∼50 kcal/mol for LaOÂ(OH) and La<sub>2</sub>O<sub>3</sub> and 64 to 76 kcal/mol for La<sub>3</sub>O<sub>4</sub>(OH) and La<sub>4</sub>O<sub>6</sub> (Δ<i>H</i><sub>298 K</sub>). Calculations on the activation of CH<sub>4</sub> by La<sub>6</sub>O<sub>9</sub> with a higher coordination number for both the La and
O sites than La<sub>4</sub>O<sub>6</sub> 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–CH<sub>3</sub> bond energies calculated at
the DFT level with the B3LYP and PBE functionals were compared with
those calculated at the CCSDÂ(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 CCSDÂ(T)
values. Although the O<sup>2–</sup> sites in these cluster
models were predicted to be less reactive toward CH<sub>4</sub> than
the O<sup>–</sup> sites modeled by the nonstoichiometric La<sub>2</sub>O<sub>3.33</sub>(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 O<sub>2</sub><sup>2–</sup> site modeled on the stoichiometric La<sub>2</sub>O<sub>3</sub>(001)
surface, which suggests the relevance of the lattice oxygen sites
on the La<sub>2</sub>O<sub>3</sub> catalyst surfaces in the OCM reaction
Role of Peroxides on La<sub>2</sub>O<sub>3</sub> Catalysts in Oxidative Coupling of Methane
Density functional theory and coupled
cluster theory [CCSDÂ(T)] calculations reveal an important pathway
for the one-step CH<sub>3</sub>OH formation upon CH<sub>4</sub> activation
at the peroxide (O<sub>2</sub><sup>2–</sup>) site of La<sub>2</sub>O<sub>3</sub>-based catalysts for the oxidative coupling of
methane (OCM) reaction. Using modest-sized La<sub>4</sub>O<sub>7</sub> and La<sub>6</sub>O<sub>10</sub> clusters as catalyst models, two
types of structures for the O<sub>2</sub><sup>2–</sup> site
were predicted, with the less stable structure (type <b>II</b>) more reactive with CH<sub>4</sub> than the more stable structure
(type <b>I</b>). CH<sub>4</sub> activation at the O<sub>2</sub><sup>2–</sup> site can always occur via the above pathway,
and for the smaller La<sub>2</sub>O<sub>4</sub> cluster and the type <b>I</b> structure of La<sub>4</sub>O<sub>7</sub>, an alternative
pathway leading to La–CH<sub>3</sub> bond formation was also
predicted, similar to that at the oxide (O<sup>2–</sup>) site
from our previous study. For the type <b>I</b> structure of
La<sub>4</sub>O<sub>7</sub>, the energy barrier for La–CH<sub>3</sub> bond formation is lower than that for CH<sub>3</sub>OH formation,
but both are higher than that for CH<sub>3</sub>OH formation for the
type <b>II</b> structure of La<sub>4</sub>O<sub>7</sub>. The
O<sub>2</sub><sup>2–</sup> site was predicted to be much less
reactive with CH<sub>4</sub> than the oxide (O<sup>2–</sup>) site, and can lead to CH<sub>3</sub>OH formation, which is considered
as a side reaction. Thus, our calculations do not appear to support
the central role previously proposed for the O<sub>2</sub><sup>2–</sup> site for La<sub>2</sub>O<sub>3</sub>-based catalysts for the OCM
reaction. However, considering the catalytic and redox nature of this
reaction, both the O<sup>2–</sup> and O<sub>2</sub><sup>2–</sup> sites may still play important roles in the whole catalytic cycle
CO<sub>2</sub> Chemisorption and Its Effect on Methane Activation in La<sub>2</sub>O<sub>3</sub>‑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
La<sub>2</sub>O<sub>3</sub> catalyst using the cluster model and its
effect on subsequent CH<sub>4</sub> activation. Physisorption and
chemisorption energies as well as energy barriers for the reaction
of CO<sub>2</sub> and La<sub>2</sub>O<sub>3</sub> clusters, and the
reaction of CH<sub>4</sub> with the CO<sub>3</sub><sup>2–</sup> site on the resulting clusters, were predicted. Our calculations
show that CO<sub>2</sub> chemisorption at the La<sup>3+</sup>–O<sup>2–</sup> pair sites is thermodynamically and kinetically very
favorable due to the strong basicity of the O<sup>2–</sup> site
on La<sub>2</sub>O<sub>3</sub>, which leads to the formation of the
La<sup>3+</sup>–CO<sub>3</sub><sup>2–</sup> pair sites.
In addition, CH<sub>4</sub> activation at the La<sup>3+</sup>–CO<sub>3</sub><sup>2–</sup> pair sites is similar to that at the
La<sup>3+</sup>–O<sup>2–</sup> pair sites, which results
in the formation of the bicarbonate species and the La–CH<sub>3</sub> bond, although the La<sup>3+</sup>–CO<sub>3</sub><sup>2–</sup> pair sites are much less reactive with CH<sub>4</sub> in terms of both thermodynamics and kinetics. Further thermodynamical
calculations show that the CO<sub>3</sub><sup>2–</sup> 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 CO<sub>3</sub><sup>2–</sup> site is unlikely to be the active site in La<sub>2</sub>O<sub>3</sub>-catalyzed oxidative coupling of methane, and CO<sub>2</sub> as a
major byproduct is likely to act as a poison to the La<sub>2</sub>O<sub>3</sub>-based catalysts especially at modest reaction temperature
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