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3. Accuracy and Error Sources of the Rietveld Full Pattern Fitting Method in Quantitative Analysis of Illite Ores

Author

CHEN Aiqing, ZHANG Lixue, LI Qiang, ZHU Jianxi, LI Shangying, and HE Hongping

Subjects
illite, the rietveld full pattern fitting method, accuracy, error sources, x-ray diffraction, structural refinement, Geology, QE1-996.5, Ecology, QH540-549.5
Abstract

BACKGROUND Illite is an important mineral resource. It is of great theoretical and practical significance to accurately obtain the mineral composition and content of illite ores. The Rietveld full pattern fitting method uses the whole diffraction pattern for analysis and shows high accuracy. However, due to the lack of pure illite samples, the accuracy and error sources of this method for analyzing the content of illite ores are not clearly known at present. OBJECTIVES To understand the accuracy and error sources of the Rietveld full pattern fitting method in quantitative analysis of illite ores. METHODS The Rietveld full pattern fitting method was used to quantitatively analyze artificial and natural illite ore samples. The results of X-ray fluorescence spectrometry (XRF) of natural illite ores were compared with the chemical compositions calculated from the mineral contents by the Rietveld method. RESULTS The results showed that the maximum absolute error ranges of illite-quartz binary mixtures, illite-quartz-albite ternary mixtures, and illite-quartz-albite-calcite-kaolinite multiple mixtures were -0.9%-0.9%, -1.9%-1.6%, and -2.3%-1.6%, respectively. The chemical compositions of natural illite ores calculated by Rietveld method were in good agreement with the results of XRF. This indicated that the Rietveld method had high accuracy in the quantitative analysis of mineral contents of natural illite ore samples. The error sources were mainly affected by the illite structural model, atomic thermal displacement parameters Uiso, and preferred orientation. CONCLUSIONS A reasonable structural model of illite should be chosen according to the actual samples. The values of atomic thermal vibration Uiso should be reasonably set according to the references. Preferred orientation should be decreased as much as possible during the sample preparation.

Published
2022
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4. Optimizing sustainability of land resource utilization: a comprehensive analysis of practices in the Tarim Basin, China

Author

Song, Yifei, primary, Wu, Weicheng, additional, Zhang, Yanfei, additional, Zhu, Minqiang, additional, Ke, Xinxin, additional, Li, Yuan, additional, He, Yecheng, additional, Zhou, Cuimin, additional, Li, Wenjing, additional, Jing, Rong, additional, Song, Peixia, additional, Fu, Linqian, additional, Mao, Chunling, additional, Xie, Meng, additional, Song, Xiaoping, additional, Chen, Aiqing, additional, Li, Sicheng, additional, Li, Aohui, additional, and Song, Yingxu, additional

Published
2024
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6. Asymmetric Reflectance and Cluster Size Effects in Silver Percolation Films

Author

Kuhta, Nicholas A., Chen, Aiqing, Hasegawa, Keisuke, Deutsch, Miriam, and Podolskiy, Viktor A.

Subjects
Physics - Optics
Abstract

We develop a quantitative description of giant asymmetry in reflectance, recently observed in semicontinuous metal films. The developed scaling-theory based technique reproduces the spectral properties of semicontinuous composites, as well as provides insight into the origin of experimentally observed loss, reflectance, and transmittance anomalies in the vicinity of the percolation threshold., Comment: 6 pages, 5 figures

Published
2011
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7. Tunable asymmetric reflectance in silver films near the percolation threshold

Author

Chen, Aiqing and Deutsch, Miriam

Subjects
Physics - Optics
Abstract

We report on the optical characterization of semicontinuous nanostructured silver films exhibiting tunable optical reflectance asymmetries. The films are obtained using a multi-step process, where a nanocrystalline silver film is first chemically deposited on a glass substrate and then subsequently coated with additional silver via thermal vacuum-deposition. The resulting films exhibit reflectance asymmetries whose dispersions may be tuned both in sign and in magnitude, as well as a universal, tunable spectral crossover point. We obtain a correlation between the optical response and charge transport in these films, with the spectral crossover point indicating the onset of charge percolation. Such broadband, dispersion-tunable asymmetric reflectors may find uses in future light-harvesting systems., Comment: 18 pages, 5 figures, accepted by Journal of Applied Physics

Published
2010
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8. Land Use/Cover Change Prediction Based on a New Hybrid Logistic-Multicriteria Evaluation-Cellular Automata-Markov Model Taking Hefei, China as an Example

Author

He, Yecheng, primary, Wu, Weicheng, additional, Xie, Xinyuan, additional, Ke, Xinxin, additional, Song, Yifei, additional, Zhou, Cuimin, additional, Li, Wenjing, additional, Li, Yuan, additional, Jing, Rong, additional, Song, Peixia, additional, Fu, Linqian, additional, Mao, Chunlian, additional, Xie, Meng, additional, Li, Sicheng, additional, Li, Aohui, additional, Song, Xiaoping, additional, and Chen, Aiqing, additional

Published
2023
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9. Metamaterial Coatings for Broadband Asymmetric Mirrors

Author

Chen, Aiqing, Hasegawa, Keisuke, Deutsch, Miriam, and Podolskiy, Viktor A.

Subjects
Physics - Optics
Abstract

We report on design and fabrication of nano-composite metal-dielectric thin film coatings with high reflectance asymmetries. Applying basic dispersion engineering principles to model a broadband and large reflectance asymmetry, we obtain a model dielectric function for the metamaterial film, closely resembling the effective permittivity of disordered metal-dielectric nano-composites. Coatings realized using disordered nanocrystalline silver films deposited on glass substrates confirm the theoretical predictions, exhibiting symmetric transmittance, large reflectance asymmetries and a unique flat reflectance asymmetry., Comment: 4 pages, 4 figures, submitted to Optics Letters

Published
2006
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22. Liguowuite, WO3, a new member of the A-site vacant perovskite type minerals from the Panzhihua–Xichang region, China

Author

Xue, Yuan, Sun, Ningyue, He, Hongping, Chen, Aiqing, and Yang, Yiping

Abstract

A new member of the non-stoichiometric perovskite group mineral species, liguowuite, ideally WO3, has been found in the Neoproterozoic Sinian biotite-quartz monzonite in the southern part of the Panzhihua–Xichang region (Nanyang village: 26∘46′8.21′′ N, 101∘27′13.86′′ E), China. It is associated with hornblende, pargasite, ferro-hornblende, annite, hydrobiotite, phlogopite, orthoclase, microcline, albite, quartz, kaolinite, ilmenite, goethite, hematite, magnetite, pyrite, zircon, zoisite, titanite, epidote, diopside, tourmaline, almandine, fluorapatite, monazite-(Ce), allanite-(Ce), bastnäsite-(Ce), xenotime-(Y), scheelite, moissanite, tellurite, wumuite, and tewite. Liguowuite occurs as greenish yellow prisms, ranging from 0.05 to 0.1 mm in diameter, and it is transparent with a greasy luster and a white streak. Liguowuite exhibits a triclinic pseudomorphism composed of nanoparticles with many cracks and nanovoids. This mineral is brittle and has a Mohs hardness value of approximately 3–4. The calculated density is 7.22 g cm−3. Electron microprobe analyses gave (average weight percent, wt %, of 15 spot analyses of 4 samples) K2O = 0.01, WO3 = 99.23, TeO2 = 0.03, CaO = 0.06, Na2O = 0.04, and total 99.37, yielding the empirical formula W1.00O3, based on Oapfu=3 and ideally WO3. The strongest five diffraction lines (d Å (I)(hkl)) are 3.8552 (88)(002), 3.7685 (88)(020), 3.6590 (100)(–200), 2.6928 (43)(022), and 2.6258 (60)(202). Liguowuite is monoclinic and is in space group P21/n, with a= 7.32582(18) Å, b= 7.54767(18) Å, c= 7.71128(18) Å, β= 90.678(3)∘, V= 426.348(19) Å3, and Z= 8. The crystal structure data were refined using the Rietveld refinement method and X-ray powder diffraction data. The reliability factors (R factors) were Rwp= 0.0604 and Rp= 0.0454, with χ2 = 1.707. Liguowuite consists of corner-sharing distorted and tilted [WO6] octahedra, in which the W atoms are off-center and form six W–O bonds ranging from 1.7 to 2.2 Å with the surrounding oxygen atoms. According to the hierarchical scheme for perovskite supergroup minerals, liguowuite is the first reported example of A-site vacant single oxide, i.e., a new perovskite subgroup.

Published
2022

23. Crystal structure of Al-rich fluorophlogopite, K1.0(Mg2.8Al0.2)(Si2.8Al1.2)O10F2

Author

Chen Aiqing and Zhang Lixue

Subjects
Inorganic Chemistry, 0209 industrial biotechnology, Crystallography, 020901 industrial engineering & automation, Chemistry, General Materials Science, 02 engineering and technology, Crystal structure, 010403 inorganic & nuclear chemistry, Condensed Matter Physics, 01 natural sciences, 0104 chemical sciences
Abstract

K1.0(Mg2.8Al0.2)(Si2.8Al1.2)O10F2, monoclinic, C2/m (no. 12), a = 5.3040(11) Å, b = 9.2288(18) Å, c = 10.1286(20) Å, β = 100.173(3)°, V = 488.00(17) Å3, Z = 2, R gt (F) = 0.0387, wR ref (F 2) = 0.1086, T = 298 K.

Published
2021
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30. Landslide susceptibility assessment through multi-model stacking and meta-learning in Poyang County, China

Author

Song, Yong, Song, Yingxu, Wang, Chengnan, Wu, Linwei, Wu, Weicheng, Li, Yuan, Li, Sicheng, and Chen, Aiqing

Abstract

AbstractThis study aims to evaluate the effectiveness of various individual machine learning and their ensemble techniques such as Stacking, Voting and Meta-learning in landslide susceptibility assessment taking Poyang, Jiangxi, China as an example. Multi-source geo-environmental data including field surveys, Sentinel-2A/B satellite images, Digital Elevation Models (DEM), and geological and hydrological data were utilized to construct and validate landslide susceptibility models. Results show that the Stacking Classifier outperformed other models, achieving the highest F1 Score of 0.846 and AUC (Area Under ROC Curve) of 0.923, demonstrating its strong predictivity, followed by the Voting Classifier with the F1 Score of 0.829 and AUC of 0.922. Among the individual models, the Multi-Layer Perceptron (MLP) performed best with the F1 Score of 0.828 and AUC of 0.904. Furthermore, the explainable Artificial Intelligence (XAI) technique was applied to better understand the mechanism of classifiers in predicting landslide susceptibility and it suggests a significant correlation between land use, distance to fault, and landslide occurrences. In conclusion, Stacking and Voting hybrid learning models show clear advantages over the individual ones for landslide risk zoning. The results of study may provide technical support for disaster mitigation efforts and future urban planning in areas prone to landslides in Poyang.

Published
2024
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32. Gestational diabetes mellitus prediction model: A risk factors analysis of pregnant women with gestational diabetes mellitus but have normal oral glucose tolerance test results in the second trimester of pregnancy

Author

Lu, Jiayu, primary, Zhang, Song, additional, Jiang, Hongqing, additional, Yang, Lin, additional, Hao, Dongmei, additional, Yang, Yimin, additional, Li, Xuwen, additional, Chen, Aiqing, additional, Shao, Jing, additional, and Liu, Xiaohong, additional

Published
2021
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34. Establishment of a personalized fetal growth curve model

Author

Bao, Xinyu, primary, Wang, Yan, additional, Zhang, Song, additional, Yang, Lin, additional, Liu, Guoli, additional, Yang, Yimin, additional, Li, Xuwen, additional, Hao, Dongmei, additional, Chen, Aiqing, additional, Liu, Xiaohong, additional, and Shao, Jing, additional

Published
2021
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37. Periodic and non-periodic stacking in molybdenite (MoS2) revealed by STEM.

Author

Yang, Yiping, He, Hongping, Xian, Haiyang, Xi, Jiaxin, Wu, Xiao, Chen, Aiqing, Zhu, Jianxi, and Xu, Huifang

Subjects
SUPERSATURATION, MOLYBDENITE, LASER ablation inductively coupled plasma mass spectrometry, TRACE elements
Abstract

Results Disordered stacking in molybdenite Micro X-ray diffraction ( -XRD) pattern in Figure 2a revealed that the molybdenite comprised a mixture of 2 I H i SB 1 sb and 3 I R i polytypes (2 I H i SB 1 sb /3 I R i 9:1) ([37]). Keywords: Molybdenite (MoS2); polytype; non-equilibrium crystallization; HAADF-STEM; layered minerals; stacking fault; Applications of Fluid; Mineral; and Melt Inclusions EN Molybdenite (MoS2) polytype non-equilibrium crystallization HAADF-STEM layered minerals stacking fault Applications of Fluid Mineral and Melt Inclusions 997 1006 10 06/01/22 20220601 NES 220601 Introduction Molybdenite (MoS SB 2 sb ) is a layered sulfide mineral that commonly occurs in hydrothermal ore deposits and, like other layered minerals, exhibits polytypism. Graph: Figure 2 Micro X-ray diffraction ( -XRD) and selected-area electron diffraction (SAED) patterns, and transmission electron microscopy (TEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images of a disordered molybdenite particle. [Extracted from the article]

Published
2022
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38. Periodic and non-periodic stacking in molybdenite (MoS2) revealed by STEM

Author

Yang, Yiping, He, Hongping, Xian, Haiyang, Xi, Jiaxin, Wu, Xiao, Chen, Aiqing, Zhu, Jianxi, and Xu, Huifang

Abstract

Polytypism is a typical feature of layered minerals with differences only in stacking sequences. There is no obvious “phase” boundary among different polytypes, although the frequency of polytypes occurrence is related to its crystallization environment. In the past decades, X‑ray studies of molybdenite specimens from a variety of geological environments have revealed that most molybdenite crystals contain both 2H1(hexagonal) and 3R(rhombohedral) polytypes. However, the stacking sequences of these molybdenite polytypic intergrowths and their formation mechanism are not well understood. Here, we report stacking faults and domains of long-period polytypes identified by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) in a molybdenite sample from a carbonatite vein in the Huanglongpu Mo-Pb ore deposit in Qinling orogenic belt, Northern China. Several layers of disordered domains intergrown with ordered 2H1domain were recognized based on the contrast in HAADF image with one-dimensional lattice fringes. In addition, a 30-layer long-period polytype was unambiguously identified by a STEM image. The stacking sequences of 4-, 6-, and 8-layer disordered domains and the 30-layer long-period polytype were further examined using HRSTEM images at the atomic resolution. A 2H3polytype with three repetitions was also discovered in the sample. We propose that non-equilibrium conditions related to the fluctuation of fluid composition during crystallization resulted in the oscillation of 2H1and 3Rpolytypes and intergrowth of various disordered domains. More broadly, our study demonstrates that HAADF-STEM imaging method may be applicable for studying other disordered layered crystals and twinned minerals.

Published
2022
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45. Severe white matter astrocytopathy in CADASIL

Author

Hase, Yoshiki, primary, Chen, Aiqing, additional, Bates, Letitia L., additional, Craggs, Lucinda J.L., additional, Yamamoto, Yumi, additional, Gemmell, Elizabeth, additional, Oakley, Arthur E., additional, Korolchuk, Viktor I., additional, and Kalaria, Raj N., additional

Published
2018
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47. Effects of environmental enrichment on white matter glial responses in a mouse model of chronic cerebral hypoperfusion

Author

Hase, Yoshiki, primary, Craggs, Lucinda, additional, Hase, Mai, additional, Stevenson, William, additional, Slade, Janet, additional, Lopez, Dianne, additional, Mehta, Rubin, additional, Chen, Aiqing, additional, Liang, Di, additional, Oakley, Arthur, additional, Ihara, Masafumi, additional, Horsburgh, Karen, additional, and Kalaria, Raj N., additional

Published
2017
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49. The effects of environmental enrichment on white matter pathology in a mouse model of chronic cerebral hypoperfusion

Author

Hase, Yoshiki, primary, Craggs, Lucinda, additional, Hase, Mai, additional, Stevenson, William, additional, Slade, Janet, additional, Chen, Aiqing, additional, Liang, Di, additional, Ennaceur, Abdel, additional, Oakley, Arthur, additional, Ihara, Masafumi, additional, Horsburgh, Karen, additional, and Kalaria, Raj N, additional

Published
2017
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