153 research outputs found
Knowledge Graph Question Answering for Materials Science (KGQA4MAT): Developing Natural Language Interface for Metal-Organic Frameworks Knowledge Graph (MOF-KG)
We present a comprehensive benchmark dataset for Knowledge Graph Question
Answering in Materials Science (KGQA4MAT), with a focus on metal-organic
frameworks (MOFs). A knowledge graph for metal-organic frameworks (MOF-KG) has
been constructed by integrating structured databases and knowledge extracted
from the literature. To enhance MOF-KG accessibility for domain experts, we aim
to develop a natural language interface for querying the knowledge graph. We
have developed a benchmark comprised of 161 complex questions involving
comparison, aggregation, and complicated graph structures. Each question is
rephrased in three additional variations, resulting in 644 questions and 161 KG
queries. To evaluate the benchmark, we have developed a systematic approach for
utilizing ChatGPT to translate natural language questions into formal KG
queries. We also apply the approach to the well-known QALD-9 dataset,
demonstrating ChatGPT's potential in addressing KGQA issues for different
platforms and query languages. The benchmark and the proposed approach aim to
stimulate further research and development of user-friendly and efficient
interfaces for querying domain-specific materials science knowledge graphs,
thereby accelerating the discovery of novel materials.Comment: In 17th International Conference on Metadata and Semantics Research,
October 202
Metadata for Scientific Experiment Reporting: A Case Study in Metal-Organic Frameworks
Research methods and procedures are core aspects of the research process.
Metadata focused on these components is critical to supporting the FAIR
principles, particularly reproducibility. The research reported on in this
paper presents a methodological framework for metadata documentation supporting
the reproducibility of research producing Metal Organic Frameworks (MOFs). The
MOF case study involved natural language processing to extract key synthesis
experiment information from a corpus of research literature. Following, a
classification activity was performed by domain experts to identify
entity-relation pairs. Results include: 1) a research framework for metadata
design, 2) a metadata schema that includes nine entities and two relationships
for reporting MOF synthesis experiments, and 3) a growing database of MOF
synthesis reports structured by our metadata scheme. The metadata schema is
intended to support discovery and reproducibility of metal-organic framework
research and the FAIR principles. The paper provides background information,
identifies the research goals and objectives, research design, results, a
discussion, and the conclusion.Comment: Accepted by the 17th International Conference on Metadata and
Semantics Researc
Building Open Knowledge Graph for Metal-Organic Frameworks (MOF-KG): Challenges and Case Studies
Metal-Organic Frameworks (MOFs) are a class of modular, porous crystalline
materials that have great potential to revolutionize applications such as gas
storage, molecular separations, chemical sensing, catalysis, and drug delivery.
The Cambridge Structural Database (CSD) reports 10,636 synthesized MOF crystals
which in addition contains ca. 114,373 MOF-like structures. The sheer number of
synthesized (plus potentially synthesizable) MOF structures requires
researchers pursue computational techniques to screen and isolate MOF
candidates. In this demo paper, we describe our effort on leveraging knowledge
graph methods to facilitate MOF prediction, discovery, and synthesis. We
present challenges and case studies about (1) construction of a MOF knowledge
graph (MOF-KG) from structured and unstructured sources and (2) leveraging the
MOF-KG for discovery of new or missing knowledge.Comment: Accepted by the International Workshop on Knowledge Graphs and Open
Knowledge Network (OKN'22) Co-located with the 28th ACM SIGKDD Conferenc
Gapless spinons and a field-induced soliton gap in the hyper-honeycomb Cu oxalate framework compound [(CH)NH]Cu(CO)
We report a detailed study of the specific heat and magnetic susceptibility
of single crystals of a spin liquid candidate: the hyper-honeycomb Cu oxalate
framework compound [(CH)NH]Cu(CO). The specific
heat shows no anomaly associated with a magnetic transition at low temperatures
down to 180 mK in zero magnetic field. We observe a large linear-in-
contribution to the specific heat , mK/mol K,
at low temperatures, indicative of the presence of fermionic excitations
despite the Mott insulating state. The low- specific heat is strongly
suppressed by applied magnetic fields , which induce an energy gap, , in the spin-excitation spectrum. We use the four-component relativistic
density-functional theory (DFT) to calculate the magnetic interactions,
including the Dzyaloshinskii-Moriya antisymmetric exchange, which causes an
effective staggered field acting on one copper sublattice. The magnitude and
field dependence of the field-induced gap, , are
accurately predicted by the soliton mass calculated from the sine-Gordon model
of weakly coupled antiferromagnetic Heisenberg chains with all parameters
determined by our DFT calculations. Thus our experiment and calculations are
entirely consistent with a model of
[(CH)NH]Cu(CO) in which anisotropic magnetic
exchange interactions due to Jahn-Teller distortion cause one copper sublattice
to dimerize, leaving a second sublattice of weakly coupled antiferromagnetic
chains. We also show that this model quantitatively accounts for the measured
temperature-dependent magnetic susceptibility. Thus
[(CH)NH]Cu(CO) is a canonical example of a
one-dimensional spin-1/2 Heisenberg antiferromagnet and not a
resonating-valence-bond quantum spin liquid, as previously proposed.Comment: 8 pages, 6 figure
All-in-one synthesis of mesoporous silicon nanosheets from natural clay and their applicability to hydrogen evolution
Silicon nanosheets have attracted much attention owing to their novel electronic and optical properties and compatibility with existing silicon technology. However, a cost-effective and scalable technique for synthesizing these nanosheets remains elusive. Here, we report a novel strategy for producing silicon nanosheets on a large scale through the simultaneous molten-salt-induced exfoliation and chemical reduction of natural clay. The silicon nanosheets thus synthesized have a high surface area, are ultrathin (similar to 5 nm) and contain mesoporous structures derived from the oxygen vacancies in the clay. These advantages make the nanosheets a highly suitable photocatalyst with an exceptionally high activity for the generation of hydrogen from a water-methanol mixture. Further, when the silicon nanosheets are combined with platinum as a cocatalyst, they exhibit high activity in KOH (15.83 mmol H-2 per s per mol Si) and excellent photocatalytic activity with respect to the evolution of hydrogen from a water-methanol mixture (723 mu mol H-2 per h per g Si).clos
Main-chain thermotropic liquid crystalline polymers under shear A dynamic scattering study
SIGLEAvailable from British Library Document Supply Centre-DSC:D199969 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Shear-induced long-range spatial correlation and banded texture in thermotropic copolyester.
In situ small-angle light scattering (SALS) has enabled to
elucidate shear-induced orientation correlations and monitor their
relaxation in the thermotropic copolyester of 60\un{mol{\%}} hydroxybenzoic acid
(B) and 40\un{mol{\%}} ethylene terephthalate (ET). At 280 °C B-ET displays
a nematic polydomain texture, the SALS and WAXS patterns are amorphous and
isotropic. Applying steady shear, optical defect multiplication occurred and
the microdomain sizes were reduced. However, the SALS pattern now showed
anisotropy, the SALS pattern transitioned from a unimodal to a bimodal
orientation. After cessation of shear, the orientation correlation rapidly
relaxed to a polydomain and the SALS pattern became again isotropic. Above a
threshold shear rate of about \dot{\gamma}_c \sim 2\un{s^{ - 1}} shear
now induced line defects oriented nearly orthogonal to the velocity axis.
The texture relaxation above was also distinctly
different, the well-known “banded texture” was formed upon cessation of
shear. In situ X-ray scattering showed that the molecular chains always
aligned along the flow direction regardless of the shear rate. However, the
degree of macromolecular alignment improved significantly above and this is a condition to obtain the banded texture
A rheo-optical and dynamic X-ray-scattering study of flow-induced textures in main-chain thermotropic liquid-crystalline polymers. The influemce of molecular weight
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