A novel modification of simulated moving bed (SMB) technology, referred to as fractionation and feedback SMB (FF-SMB), has been introduced recently. This concept is based on fractionating one or both outlet streams and feeding the off-spec fractions back into the unit alternatingly with the original feed mixture. In this paper, the optimization problem of FF-SMB realizing one outlet fractionation is considered. A mathematical optimization framework based on a detailed process model is presented which allows to evaluate quantitatively the potential of this operating scheme. Detailed optimization studies have been carried out for a difficult separation characterized by small selectivity and low column efficiency. The results reveal that the proposed fractionation and feedback regime can be significantly superior to the classical SMB chromatography, in terms of both feed throughput and desorbent consumption. The effect of the feeding sequence on the performance of FF-SMB is also examined.
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http://dx.doi.org/10.1016/j.chroma.2010.06.031 | DOI Listing |
Natl Sci Rev
February 2025
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
Climate warming may induce substantial changes in the ecosystem carbon cycle, particularly for those climate-sensitive regions, such as alpine grasslands on the Tibetan Plateau. By synthesizing findings from warming experiments, this review elucidates the mechanisms underlying the impacts of experimental warming on carbon cycle dynamics within these ecosystems. Generally, alterations in vegetation structure and prolonged growing season favor strategies for enhanced ecosystem carbon sequestration under warming conditions.
View Article and Find Full Text PDFHeliyon
January 2025
Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas Norte 152, Col. San Bartolo Atepehuacán, C.P. 07730, Ciudad de México, Mexico.
The hydrogen produced ( ) in the Catalytic Naphtha Reforming (CNR) is important in quantity and quality, for the feedback of the process and for supplying the hydrotreatment processes in current refineries. In this work it is presented a study by process simulation using ® for finding operative transitional modes that simultaneously improve quality of the reformate and hydrogen production of the CNR. The operative conditions that were studied correspond to the recirculation ratio of hydrogen/hydrocarbon ( ), with values between 2 and 6, and the temperature (), between 450 and 525 °C, in order to determining the best operative transitional route from the initial operative state to a local improved state, applying the method of superposition of response surfaces and criteria assessment of improvement in quality and quantity of hydrogen produced.
View Article and Find Full Text PDFSci Total Environ
January 2025
Department of Environment and Forest Resources, College of Agriculture and Life Sciences, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea. Electronic address:
Enhancing the strength of forest carbon sinks is critical in the wake of the accelerating global climate change and intensifying greenhouse effect. However, the regional patterns and environmental controls of forest litter, a major carbon pool and entry pathway from tree-to-soil systems, remain uncertain. Herein, we consolidated up to a decade of data from six ecological studies (totaling 28 stands) conducted across South Korea between 1999 and 2022 (spanning 23 years) to examine variations in total and component-based litterfall with geo-topography and climate.
View Article and Find Full Text PDFAims: Risk prediction indices used in worsening heart failure (HF) vary in complexity, performance, and the type of datasets in which they were validated. We compared the performance of seven risk prediction indices in a contemporary cohort of patients hospitalized for HF.
Methods And Results: We assessed the performance of the Length of stay and number of Emergency department visits in the prior 6 months (LE), Length of stay, number of Emergency department visits in the prior 6 months, and admission N-Terminal prohormone of brain natriuretic peptide (NT-proBNP (LENT), Length of stay, Acuity, Charlson co-morbidity index, and number of Emergency department visits in the prior 6 months (LACE), Get With The Guidelines Heart Failure (GWTG), Readmission Risk Score (RRS), Enhanced Feedback for Effective Cardiac Treatment model (EFFECT), and Acute Decompensated Heart Failure National Registry (ADHERE) risk indices among consecutive patients hospitalized for HF and discharged alive from January 2017 to December 2019 in a network of hospitals in England.
Cancers (Basel)
December 2024
Radiation Oncology Department, Centre Frederic Joliot, 76000 Rouen, France.
Background/objectives: An on-board imager on a linear accelerator allows the acquisition of kV-2D images during irradiation. Overlaying specific structures on these images enables the visual verification of movement at regular frequencies. Our aim was to validate this tracking method for the stereotactic treatment of bone metastases.
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