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789 results on '"Qin, Xiaoyan"'

211. Fundamentals and US natural gas price dynamics

Author

Qin, Xiaoyan, Bessler, David A., Leatham, David J., Wu, Ximing, and Gan, Li

Subjects
GARCH, Resource /Energy Economics and Policy, Markov-switching model, US natural gas price behaviors
Abstract

Investigation into the relations between market fundamentals and US natural gas prices is carried out in the regime-switching framework. To test the hypothesis that US natural gas market may switch between two states of market: bullish market and bearish market, a 2-state regime-switching model with Markov transition chain is carried out. GARCH effects are also built into the model to account for the conditional heteroskedasticity. Short-term forecasts based on the regime-switching model are also provided. Empirical results suggest that real world natural gas price behavior is far more complicated than that predicted by fundamental models. Volatility which cannot be explained by fundamentals plays an essential role in natural gas price behavior. The major contribution of this study lies in the effort to ease the deficiency of current fundamental-based models on commodity pricing due to high volatility by applying regime-switching models.

Published
2010
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212. Incidental Memory of Younger and Older Adults for Objects Encountered in a Real World Context

Author

Psicología evolutiva y de la educación, Bilakaeraren eta hezkuntzaren psikologia, Qin, Xiaoyan, Bochsler, Tiana M., Aizpurua Sanz, Alaitz, Cheong, Allen M. Y., Koutstaal, Wilma, Legge, Gordon E., Psicología evolutiva y de la educación, Bilakaeraren eta hezkuntzaren psikologia, Qin, Xiaoyan, Bochsler, Tiana M., Aizpurua Sanz, Alaitz, Cheong, Allen M. Y., Koutstaal, Wilma, and Legge, Gordon E.

Abstract

Effects of context on the perception of, and incidental memory for, real-world objects have predominantly been investigated in younger individuals, under conditions involving a single static viewpoint. We examined the effects of prior object context and object familiarity on both older and younger adults' incidental memory for real objects encountered while they traversed a conference room. Recognition memory for context-typical and context-atypical objects was compared with a third group of unfamiliar objects that were not readily named and that had no strongly associated context. Both older and younger adults demonstrated a typicality effect, showing significantly lower 2-alternative-forced-choice recognition of context-typical than context-atypical objects; for these objects, the recognition of older adults either significantly exceeded, or numerically surpassed, that of younger adults. Testing-awareness elevated recognition but did not interact with age or with object type. Older adults showed significantly higher recognition for context-atypical objects than for unfamiliar objects that had no prior strongly associated context. The observation of a typicality effect in both age groups is consistent with preserved semantic schemata processing in aging. The incidental recognition advantage of older over younger adults for the context-typical and context-atypical objects may reflect aging-related differences in goal-related processing, with older adults under comparatively more novel circumstances being more likely to direct their attention to the external environment, or age-related differences in top-down effortful distraction regulation, with older individuals' attention more readily captured by salient objects in the environment. Older adults' reduced recognition of unfamiliar objects compared to context-atypical objects may reflect possible age differences in contextually driven expectancy violations. The latter finding underscores the theoretical and methodol

Published
2014

213. Crystal characterization of GaP epilayer grown on GaAs by atmospheric pressure metalorganic vapor phase epitaxy

Author

Jiang Min-hua, Cui Deliang, Huang Baibiao, Qin Xiaoyan, Zhang Zhaochun, and Kong Xiang-gui

Subjects
Materials science, Atmospheric pressure, Mechanical Engineering, Analytical chemistry, Atmospheric temperature range, Condensed Matter Physics, Epitaxy, Microstructure, Crystal, Condensed Matter::Materials Science, symbols.namesake, Crystallography, Perfect crystal, Mechanics of Materials, symbols, General Materials Science, Raman spectroscopy, Raman scattering
Abstract

The crystal perfection in GaP film grown on GaAs by atmospheric pressure metalorganic vapor phase epitaxy has been studied by the use of double crystal X-ray diffraction, backscattering spectrometry and Raman scattering techniques. By means of the morphology and full-width at half maximum of X-ray diffraction peak for the GaP epilayers, the growth temperature and V/III ratio were optimized. In the temperature range from 720 to 800°C and with the V/III ratio range from 10 to 80, it was concluded that the optimum growth temperature was 800°C with a V/III ratio of approximately 15. The result of backscattering spectrometry revealed that the minimum yield for the GaP epilayer grown under nearly optimized growth conditions exceeded that for a perfect crystal. In addition, the residual strain of GaP epilayer was calculated by using a biaxial stress model and Raman scattering measurement.

Published
2000

216. Enhancing the photocatalytic activity of BiOX (X = Cl, Br, and I), (BiO)2CO3 and Bi2O3 by modifying their surfaces with polar organic anions, 4-substituted thiophenolates.

Author

Xu, Benyan, An, Yang, Liu, Yuanyuan, Qin, Xiaoyan, Zhang, Xiaoyang, Dai, Ying, Wang, Zeyan, Wang, Peng, Whangbo, Myung-Hwan, and Huang, Baibiao

Abstract

When its surface is modified by using polar organic anions, 4-substituted thiophenolate anions 4-Z-C6H4S− (Z = NO2, COOH, H, CH3, and NH2), the Bi-based semiconductor BiO(HCOO) was found to exhibit a greatly enhanced photocatalytic activity. To establish the generality of this phenomenon, we examined the photocatalytic activities of other Bi-based semiconductors, BiOX (X = Cl, Br, and I), (BiO)2CO3 and Bi2O3, by modifying their surfaces with 4-carboxythiophenolate anions (4CBTs). As observed for BiO(HCOO), it is found that the surface modification with the 4CBT anions enhances the photocatalytic activities of BiOX (X = Cl, Br, and I), (BiO)2CO3 and Bi2O3, and this enhancement originates from a synergetic effect between the polarity of the polar organic anions and the internal electric field of those Bi-based semiconductors. Several factors affecting the photocatalytic activity were probed in some detail, which includes the nature of the facets and the sample sizes modified by using 4CBT anions in BiOCl and (BiO)2CO3, the structures of Bi2O3 phases as well as the electron-withdrawing or electron-donating ability of the 4-substituent Z of 4-Z-C6H4S− in BiOX (X = Cl, Br, and I). [ABSTRACT FROM AUTHOR]

Published
2017
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218. NiII Coordination to an Al-Based Metal-Organic Framework Made from 2-Aminoterephthalate for Photocatalytic Overall Water Splitting.

Author

An, Yang, Liu, Yuanyuan, An, Pengfei, Dong, Juncai, Xu, Benyan, Dai, Ying, Qin, Xiaoyan, Zhang, Xiaoyang, Whangbo, Myung‐Hwan, and Huang, Baibiao

Subjects
METAL-organic frameworks, PHOTOCATALYSIS, WATER electrolysis, PHOTOLUMINESCENCE, ABSORPTION
Abstract

The aluminum-based metal-organic framework (MOF) made from 2-aminoterephthalate is a photocatalyst for oxygen evolution. This MOF can be modified by incorporating Ni2+ cations into the pores through coordination to the amino groups, and the resulting MOF is an efficient photocatalyst for overall water splitting. [ABSTRACT FROM AUTHOR]

Published
2017
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219. Intrinsic imperfect and zero thermal quenching property for a novel β-NaYF4:Eu3+,Tb3+ red-light emitting phosphor for NUV LEDs.

Author

Ling, Shaokun, Qin, Xiaoyan, chen, Chang, Meng, Kai, Yan, Yifeng, Ming, Junyun, Liao, Sen, Huang, Yingheng, and Hou, Lei

Subjects
*TERBIUM, *CRYSTAL defects, *PHOSPHORS, *THERMAL properties, *ELECTRON paramagnetic resonance, *THERMAL electrons
Abstract

Despite long-term development of LEDs, problems urgent to resolve is still existing. The most outstanding problem to tackle is luminescent stability at high temperature working situation. In this study, a novel type of β-NaYF 4 based phosphor incorporated with Eu3+ and Tb3+ is reported. A series of β-NaYF 4 :0.065Eu3+, x Tb3+ (x = 0.001, 0.002, 0.003, 0.004, 0.005) phosphors were synthesized by hydrothermal method. The sample β-NaYF 4 :0.065Eu3+,0.002Tb3+ possesses optimal luminescent property at room temperature. The mechanism of energy transfer from Tb3+ to Eu3+ ion is quadrupole-quadrupole interactions. The sample β-NaYF 4 :0.065Eu3+,0.002Tb3+ demonstrates zero thermal quenching (ZTQ) property at 303 K to 383 K. According to XRD and XPS characterizations, nonequivalent replacement between intrinsic ion Na+ and Y3+ were discovered, which finally leads to production of crystal defects. According to electron paramagnetic resonance (EPR) characterization and density functional theory (DFT) calculation, the type of crystal defect of β-NaYF 4 :0.065Eu3+,0.002Tb3+ is confirmed to be V Y vacancies which are the predominant defect of crystal. The depths and densities of defects were calculated according to data of thermoluminescence spectra (TL spectra). Crystal defects play the role of electrons traps that could store electrons. Electrons stored in traps will be excited to excitation state of Eu3+ under the thermal stimulation to offset undesirable impact of thermal quenching (TQ), which leads to ZTQ property of the sample β-NaYF 4 :0.065Eu3+,0.002Tb3+. The CRI and CCT of fabricated WLED are 3830 K and 84.1, respectively. • The β -NaYF 4 :0.065Eu3+,0.002Tb3+ phosphor exhibits zero thermal quenching property. • The thermo-optic thermal stimulation of electrons mechanism is suggested for the effect. • The thermo-optic stimulation of electrons mechanism is induced by crystal defect. • The V Y ′′ and V Y •• vacancies are confirmed by Density functional theory (DFT). • CCT and CRI of Fabricated WLED are 3830 K and 84.1, respectively. [ABSTRACT FROM AUTHOR]

Published
2023
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239. Preparation of poly(lactide-co-glycolide) microspheres and evaluation of pharmacokinetics and tissue distribution of BDMC-PLGA-MS in rats

Author

Li, Guozhuan, Yao, Liang, Li, Jing, Qin, Xiaoyan, Qiu, Zhen, and Chen, Weidong

Abstract

Poly (lactic-co-glycolic acid) (PLGA)-based microspheres formulation of Bisdemethoxycurcum (BDMC) was prepared by emulsion-solvent evaporation method. The pharmacokinetics and tissue distribution in rats were conducted to evaluate BDMC-PLGA-MS preliminarily.

Published
2018
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240. Fabrication of In2O3/ZnO hetero-epitaxial-junctions with enhanced PEC performances

Author

Zhang, Bo, Wang, Zeyan, Zhang, Xiaoyang, Qin, Xiaoyan, Wang, Peng, Liu, Yuanyuan, Li, Mengmeng, Dai, Ying, Li, Yingjie, and Huang, Baibiao

Abstract

In2O3/ZnO hetero-epitaxial-junction photoanodes were successfully synthesized and applied for the photoelectrochemical splitting of water. With the assistance of In2O3, the light absorption of In2O3/ZnO heterojunctions can effectively expand to visible light absorption region. Due to the epitaxial relationship between (10-10) ZnO and {-211} In2O3planes, the staggered band alignments between In2O3and ZnO can produce a built in electric field at the heterojunction interface with a high quality, which can promote the charge separation and lower the charge recombination under light irradiation. Moreover, low index crystal facets, such as {001} and {111} facets, with lower surface energies can be formed spontaneously in In2O3nanoparticles due to the surface energy conservation. And the presence of In2O3{001} facets can effectively lower the onset potential and facilitate the water oxidation. With the synergistic effects mentioned above, In2O3/ZnO-6 exhibit highest photocurrent density of 2.2 mA cm−2at 0.6 V vs Ag/AgCl and IPCE value of 88.62% at 0.25 V vs Ag/AgCl (370 nm), which is 2.82 and 4.4 times as high as that of ZnO NRs and In2O3photoanodes, respectively.

Published
2017
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242. The role of Andrographolide in the prevention and treatment of liver diseases.

Author

Qin, Xiaoyan, Wang, Xi, Tian, Maoying, Dong, Zhaowei, Wang, Jin, Wang, Chao, and Huang, Qinwan

Abstract

The presence or absence of damage to the liver organ is crucial to a person's health. Nutritional disorders, alcohol consumption, and drug abuse are the main causes of liver disease. Liver transplantation is the last irrevocable option for liver disease and has become a serious economic burden worldwide. Andrographolide (AP) is one of the main active ingredients of Herba Andrographitis. It has several biological activities and has been reported to have protective and therapeutic effects against liver diseases. Earlier literature has been written on AP's role in treating inflammation and other diseases, and there has not been a systematic review on liver diseases. This review is dedicated to sorting out the research results of AP against liver diseases. Pharmacokinetics, toxicity, and nanotechnology to improve bioavailability are discussed. Finally, an outlook and assessment of its future are provided. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. PubMed and web of Science databases were used to search all relevant literature on AP for liver disease up to 2022. Studies have shown that AP plays an important role in different liver disease phenotypes, mainly through anti-inflammatory and antioxidant activities. AP regulates HO-1 and inhibits hepatitis virus replication. It affects the NF-κB pathway, downregulates inflammatory factors such as IL-1β, IL-6, and TNF-α, and reduces liver damage. In preventing liver fibrosis, AP inhibits angiogenesis and activation of hepatic stellate cells and reduces oxidative stress involved in the Nrf2 and TGF-β1/Smad pathways. In addition, AP impedes the development of liver cancer by promoting apoptosis and autonomous phagocytosis in a cell-dependent way. Interestingly, miRNAs are involved in the therapeutic process of liver cancer and hepatic fibrosis. The poor solubility of AP limits the development of dosage forms. Therefore, the advent of nanoformulations has improved bioavailability. Although the effect of AP is dose- and time-dependent, the magnitude of its toxicity is not negligible. Some clinical trials have shown that AP has mild side effects. AP, as an effective natural product, has a good effect on the liver disease through multiple pathways and targets. However, the dose reaches a certain level, leading to its toxicity and side effects. For better clinical application of AP, high-quality clinical and toxic intervention mechanisms are needed to validate current studies. In addition, modulation of miRNA-mediated hepatocellular carcinoma and liver fibrosis and synergistic action with drugs may be the future focus of AP. In conclusion, AP can be regarded as an important candidate for treating different liver diseases in the future. [Display omitted] [ABSTRACT FROM AUTHOR]

Published
2023
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