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  • 1
    Online Resource
    Online Resource
    Maximizing the catalytic performance of FER zeolite in the methanol-to-hydrocarbon process by manipulating the crystal size and constructing a bifunctional system
    Royal Society of Chemistry (RSC) ; 2023
    In:  Inorganic Chemistry Frontiers
    Details
    In: Inorganic Chemistry Frontiers, Royal Society of Chemistry (RSC)
    Abstract: Although more than 250 different zeolites/zeo-type materials have been discovered to date, the industrial catalyst catalog of the zeolite-catalyzed methanol-to-hydrocarbon (MTH) process is only limited to ZSM-5 (MFI topology with a 10-membered ring (MR)) and SAPO-34 (CHA topology with 8-MR). Herein, the zeolite FER, in principle, could be an attractive alternative as it owns a two-dimensional interconnecting channel system, where a 10-MR channel is perpendicular to the 8-MR channel. However, a shorter lifetime over commercial and literature-reported synthesized FER (avg. 1 hour) is a grave concern. We have strategically integrated material design and catalysis optimization with advanced characterization to improve the catalyst durability of the zeolite FER-catalyzed MTH process. Herein, we report a unique flake-shaped FER (f-FER) zeolite with optimized physicochemical properties that led to a superior lifetime (∼3 hours) to commercial FER (∼1 hour). Upon combining f-FER zeolite with Y 2 O 3 , an unprecedented catalyst lifespan (∼20 hours) was accomplished with a preferential selectivity for C 4 –C 7 hydrocarbons. Minimizing the involvement of formaldehyde during the early stages of the MTH process favors the alkene cycle over the arene cycle, eventually extending the catalyst lifetime.
    Type of Medium: Online Resource
    ISSN: 2052-1553
    URL: Article
    DOI: 10.1039/D3QI01526B
    Language: English
    Publisher: Royal Society of Chemistry (RSC)
    Publication Date: 2023
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  • 2
    Online Resource
    Online Resource
    Extreme weather events recorded by daily to hourly resolution biogeochemical proxies of marine giant clam shells
    Proceedings of the National Academy of Sciences ; 2020
    In:  Proceedings of the National Academy of Sciences Vol. 117, No. 13 ( 2020-03-31), p. 7038-7043
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 117, No. 13 ( 2020-03-31), p. 7038-7043
    Abstract: Paleoclimate research has built a framework for Earth’s climate changes over the past 65 million years or even longer. However, our knowledge of weather-timescale extreme events (WEEs, also named paleoweather), which usually occur over several days or hours, under different climate regimes is almost blank because current paleoclimatic records rarely provide information with temporal resolution shorter than monthly scale. Here we show that giant clam shells ( Tridacna spp.) from the tropical western Pacific have clear daily growth bands, and several 2-y-long (from January 29, 2012 to December 9, 2013) daily to hourly resolution biological and geochemical records, including daily growth rate, hourly elements/Ca ratios, and fluorescence intensity, were obtained. We found that the pulsed changes of these ultra-high-resolution proxy records clearly matched with the typical instrumental WEEs, for example, tropical cyclones during the summer−autumn and cold surges during the winter. When a tropical cyclone passes through or approaches the sampling site, the growth rate of Tridacna shell decreases abruptly due to the bad weather. Meanwhile, enhanced vertical mixing brings nutrient-enriched subsurface water to the surface, resulting in a high Fe/Ca ratio and strong fluorescence intensity (induced by phytoplankton bloom) in the shell. Our results demonstrate that Tridacna shell has the potential to be used as an ultra-high-resolution archive for paleoweather reconstructions. The fossil shells living in different geological times can be built as a Geological Weather Station network to lengthen the modern instrumental data and investigate the WEEs under various climate conditions.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1916784117
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 3
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    Evaluating the efficacy of zeolites synthesized from natural clay for the methanol-to-hydrocarbon process
    Royal Society of Chemistry (RSC) ; 2023
    In:  Dalton Transactions
    Details
    In: Dalton Transactions, Royal Society of Chemistry (RSC)
    Abstract: Introducing sustainability into advanced catalytic material design is essential to address growing environmental concerns. Among them, synthesizing inorganic zeolite materials from non-traditional sources (like natural clay) offers several advantages, contributing to sustainability and environmental stewardship. With this objective, we used kaolin to synthesize zeolites with different topologies: SSZ-13 (8-MR with CHA topology), ZSM-5 (10-MR with MFI topology), and Beta (12-MR with BEA topology) (MR: member ring), where a simple and flexible synthetic protocol was adopted without any significant changes. All these zeolites were subjected to catalytic performance evaluation concerning the industrially relevant methanol-to-hydrocarbon (MTH) process. Herein, the kaolin-derived zeolites, especially ZSM-5, led to superior performance and demonstrated enhanced catalyst deactivation-resistant behavior compared to their zeolite counterparts prepared from traditional synthetic routes. Various characterization tools (including under operando conditions) were employed to understand their reactions and deactivation mechanisms. Overall, making zeolites from non-traditional sources presents a pathway for sustainable and environmentally friendly material production, offering benefits such as reduced resource dependence, lower energy consumption, and tailored physicochemical properties beneficial to catalysis. In a broader context, such a research approach contributes to the transition toward a more sustainable and circular economy.
    Type of Medium: Online Resource
    ISSN: 1477-9226 , 1477-9234
    URL: Article
    DOI: 10.1039/D3DT02131A
    Language: English
    Publisher: Royal Society of Chemistry (RSC)
    Publication Date: 2023
    detail.hit.zdb_id: 1472887-4
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  • 4
    Online Resource
    Online Resource
    Antioxidant and anti-aging activities and structural elucidation of polysaccharides from Panax notoginseng root
    Elsevier BV ; 2019
    In:  Process Biochemistry Vol. 78 ( 2019-03), p. 189-199
    Details
    In: Process Biochemistry, Elsevier BV, Vol. 78 ( 2019-03), p. 189-199
    Type of Medium: Online Resource
    ISSN: 1359-5113
    URL: Article
    DOI: 10.1016/j.procbio.2019.01.007
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2019
    detail.hit.zdb_id: 2016483-X
    SSG: 12
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  • 5
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    Online Resource
    The WD40 domain-containing protein Ehd5 positively regulates flowering in rice ( Oryza sativa )
    Oxford University Press (OUP) ; 2023
    In:  The Plant Cell ( 2023-08-30)
    Details
    In: The Plant Cell, Oxford University Press (OUP), ( 2023-08-30)
    Abstract: Heading date (flowering time), which greatly influences regional and seasonal adaptability in rice (Oryza sativa), is regulated by many genes in different photoperiod pathways. Here, we characterized a heading date gene, Early heading date 5 (Ehd5), using a modified bulked segregant analysis method. The ehd5 mutant showed late flowering under both short-day and long-day conditions, as well as reduced yield, compared to the wild type. Ehd5, which encodes a WD40 domain-containing protein, is induced by light and follows a circadian rhythm expression pattern. Transcriptome analysis revealed that Ehd5 acts upstream of the flowering genes Early heading date 1 (Ehd1), RICE FLOWERING LOCUS T 1 (RFT1), and Heading date 3a (Hd3a). Functional analysis showed that Ehd5 directly interacts with Rice outermost cell-specific gene 4 (Roc4) and Grain number, plant height, and heading date 8 (Ghd8), which might affect the formation of Ghd7–Ghd8 complexes, resulting in increased expression of Ehd1, Hd3a, and RFT1. In a nutshell, these results demonstrate that Ehd5 functions as a positive regulator of rice flowering and provide insight into the molecular mechanisms underlying heading date.
    Type of Medium: Online Resource
    ISSN: 1040-4651 , 1532-298X
    URL: Article
    DOI: 10.1093/plcell/koad223
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2023
    detail.hit.zdb_id: 623171-8
    detail.hit.zdb_id: 2004373-9
    SSG: 12
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  • 6
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    Using Particle Swarm Optimization Algorithm to Calibrate the Term Structure Model
    Hindawi Limited ; 2021
    In:  Mathematical Problems in Engineering Vol. 2021 ( 2021-1-4), p. 1-11
    Details
    In: Mathematical Problems in Engineering, Hindawi Limited, Vol. 2021 ( 2021-1-4), p. 1-11
    Abstract: One of the advantages of stochastic differential equations (SDE) is that they can follow a variety of different trends so that they can establish complex dynamic systems in the economic and financial fields. Although some estimation methods have been proposed to identify the unknown parameters in virtue of the results in the SDE model to speed up the process, these solutions only focus on using explicit approach to solve SDEs, and therefore they are not reliable to deal with data source merged being large and varied. Thus, this study makes progress in creating a new implicit way to fill in the gaps of accurately calibrating the unknown parameters in the SDE model. Essentially, the primary goal of the article is to generate rigid SDE simulation. Meanwhile, the particle swarm optimization method serves a purpose to search and simultaneously obtain the optimal estimation of the model unknown parameters in the complicated experiment of parameter space in an effective way. Finally, in an interest rate term structure model, it is verified that the method effectively deals with parameter estimation in the SDE model.
    Type of Medium: Online Resource
    ISSN: 1563-5147 , 1024-123X
    URL: Article
    DOI: 10.1155/2021/8893940
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2021
    detail.hit.zdb_id: 2014442-8
    SSG: 11
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  • 7
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    Optimal Portfolio Selection of Mean-Variance Utility with Stochastic Interest Rate
    Hindawi Limited ; 2020
    In:  Journal of Function Spaces Vol. 2020 ( 2020-11-19), p. 1-10
    Details
    In: Journal of Function Spaces, Hindawi Limited, Vol. 2020 ( 2020-11-19), p. 1-10
    Abstract: In order to tackle the problem of how investors in financial markets allocate wealth to stochastic interest rate governed by a nested stochastic differential equations (SDEs), this paper employs the Nash equilibrium theory of the subgame perfect equilibrium strategy and propose an extended Hamilton-Jacobi-Bellman (HJB) equation to analyses the optimal control over the financial system involving stochastic interest rate and state-dependent risk aversion (SDRA) mean-variance utility. By solving the corresponding nonlinear partial differential equations (PDEs) deduced from the extended HJB equation, the analytical solutions of the optimal investment strategies under time inconsistency are derived. Finally, the numerical examples provided are used to analyze how stochastic (short-term) interest rates and risk aversion affect the optimal control strategies to illustrate the validity of our results.
    Type of Medium: Online Resource
    ISSN: 2314-8888 , 2314-8896
    URL: Article
    DOI: 10.1155/2020/3153297
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2020
    detail.hit.zdb_id: 2861541-4
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  • 8
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    The Correction of Multiscale Stochastic Volatility to American Put Option: An Asymptotic Approximation and Finite Difference Approach
    Hindawi Limited ; 2021
    In:  Journal of Function Spaces Vol. 2021 ( 2021-9-17), p. 1-14
    Details
    In: Journal of Function Spaces, Hindawi Limited, Vol. 2021 ( 2021-9-17), p. 1-14
    Abstract: It has been found that the surface of implied volatility has appeared in financial market embrace volatility “Smile” and volatility “Smirk” through the long-term observation. Compared to the conventional Black-Scholes option pricing models, it has been proved to provide more accurate results by stochastic volatility model in terms of the implied volatility, while the classic stochastic volatility model fails to capture the term structure phenomenon of volatility “Smirk.” More attempts have been made to correct for American put option price with incorporating a fast-scale stochastic volatility and a slow-scale stochastic volatility in this paper. Given that the combination in the process of multiscale volatility may lead to a high-dimensional differential equation, an asymptotic approximation method is employed to reduce the dimension in this paper. The numerical results of finite difference show that the multiscale volatility model can offer accurate explanations of the behavior of American put option price.
    Type of Medium: Online Resource
    ISSN: 2314-8888 , 2314-8896
    URL: Article
    DOI: 10.1155/2021/1217665
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2021
    detail.hit.zdb_id: 2861541-4
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  • 9
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    Online Resource
    Option Pricing under the Jump Diffusion and Multifactor Stochastic Processes
    Hindawi Limited ; 2019
    In:  Journal of Function Spaces Vol. 2019 ( 2019-02-03), p. 1-12
    Details
    In: Journal of Function Spaces, Hindawi Limited, Vol. 2019 ( 2019-02-03), p. 1-12
    Abstract: In financial markets, there exists long-observed feature of the implied volatility surface such as volatility smile and skew. Stochastic volatility models are commonly used to model this financial phenomenon more accurately compared with the conventional Black-Scholes pricing models. However, one factor stochastic volatility model is not good enough to capture the term structure phenomenon of volatility smirk. In our paper, we extend the Heston model to be a hybrid option pricing model driven by multiscale stochastic volatility and jump diffusion process. In our model the correlation effects have been taken into consideration. For the reason that the combination of multiscale volatility processes and jump diffusion process results in a high dimensional differential equation (PIDE), an efficient finite element method is proposed and the integral term arising from the jump term is absorbed to simplify the problem. The numerical results show an efficient explanation for volatility smirks when we incorporate jumps into both the stock process and the volatility process.
    Type of Medium: Online Resource
    ISSN: 2314-8896 , 2314-8888
    URL: Article
    DOI: 10.1155/2019/9754679
    Language: English
    Publisher: Hindawi Limited
    Publication Date: 2019
    detail.hit.zdb_id: 2861541-4
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  • 10
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    Impact of coronavirus disease 2019 on pulmonary function in early convalescence phase
    Springer Science and Business Media LLC ; 2020
    In:  Respiratory Research Vol. 21, No. 1 ( 2020-12)
    Details
    In: Respiratory Research, Springer Science and Business Media LLC, Vol. 21, No. 1 ( 2020-12)
    Abstract: This study investigated the influence of Coronavirus Disease 2019 (COVID-19) on lung function in early convalescence phase. Methods A retrospective study of COVID-19 patients at the Fifth Affiliated Hospital of Sun Yat-sen University were conducted, with serial assessments including lung volumes (TLC), spirometry (FVC, FEV1), lung diffusing capacity for carbon monoxide (DLCO),respiratory muscle strength, 6-min walking distance (6MWD) and high resolution CT being collected at 30 days after discharged. Results Fifty-seven patients completed the serial assessments. There were 40 non-severe cases and 17 severe cases. Thirty-one patients (54.3%) had abnormal CT findings. Abnormalities were detected in the pulmonary function tests in 43 (75.4%) of the patients. Six (10.5%), 5(8.7%), 25(43.8%) 7(12.3%), and 30 (52.6%) patients had FVC, FEV1, FEV1/FVC ratio, TLC, and DLCO values less than 80% of predicted values, respectively. 28 (49.1%) and 13 (22.8%) patients had PImax and PEmax values less than 80% of the corresponding predicted values. Compared with non-severe cases, severe patients showed higher incidence of DLCO impairment (75.6%vs42.5%, p  = 0.019), higher lung total severity score (TSS) and R20, and significantly lower percentage of predicted TLC and 6MWD. No significant correlation between TSS and pulmonary function parameters was found during follow-up visit. Conclusion Impaired diffusing-capacity, lower respiratory muscle strength, and lung imaging abnormalities were detected in more than half of the COVID-19 patients in early convalescence phase. Compared with non-severe cases, severe patients had a higher incidence of DLCO impairment and encountered more TLC decrease and 6MWD decline.
    Type of Medium: Online Resource
    ISSN: 1465-993X
    URL: Article
    DOI: 10.1186/s12931-020-01429-6
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2041675-1
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