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Pre-extraction of Hemicelluloses from Poplar Chips and its Effect on Kraft Pulping
Jiachuan Chen,Tingpeng Jia,Guihua Yang,Ming He 한국펄프·종이공학회 2017 펄프.종이技術 Vol.49 No.2
Hemicelluloses are useful materials for papermaking and other biotechnological applications. Based on the concept of transformation of a chemical pulp mill into an integrated forest biorefinery, hemicelluloses are partially extracted or separated, and the remained substrate (mainly cellulose and lignin) can be further delignified for pulp. In the present work, the parameters of pre-extraction or the effect on pulp properties was investigated. The hot-water extraction and alkaline extraction prior to kraft pulping of poplar were carried out in order to partially extract hemicelluloses. It was found that the hot water extraction can obtain a mass loss of 7.72% at 140℃ for 60 min with a water-to-wood ratio of 6:1, and mass loss of woodchips increased with extraction time and temperature. While in the alkaline extraction, mass loss of woodchips reached 15.20% at 170℃ for 120 min with 3% dosage of NaOH. The concentrations of sugars depolymerized from hemicellulose in extraction liquor increased with the increase of extraction time and temperature. The residual woodchips were subjected to kraft pulping at 165℃ for 60 min with 20% effective alkali, 25% sulfidity and a liquor-to-wood ratio of 4:1. Considering the needs for resulting pulp properties, a temperature of 140℃ and a pre-extraction time of 60 min without NaOH addition were recommended as the optimum pre-extraction in this experiment.
The Characterization of Hemicellulose Extract from Corn Stalk with Stepwise Alkali Extraction
Rui Li,Guihua Yang,Jiachuan Chen,Ming He 한국펄프·종이공학회 2017 펄프.종이技術 Vol.49 No.4
In this paper, the stepwise alkaline extraction and structural characterization of hemicelluloses in corn stalk were conducted, and the theoretical support for the application of hemicelluloses was provided. Stepwise alkaline extraction of dewaxed corn stalk was performed with water, KOH aqueous solution (0.6%, 1.0%, 1.5%, and 2.0%) and a mixture of KOH solution and ethanol with a volume ratio of 2:3, and under these conditions, 2.6%, 10.2%, 16.5%, 24.8%, 11.2% and 8.7% of total hemicelluloses were extracted from corn stalk, respectively. The six types of hemicelluloses from different KOH concentration extraction process were characterized by high performance anion exchange chromatography, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analyzer (TG), carbon-13 magnetic resonance spectroscopy (13C-NMR) and hydrogen-1magnetic resonance spectroscopy (1H-NMR). Xylose was the predominant sugar constituent in the six types of hemicelluloses, and arabinose, glucose and galactose were present in small amounts. The straight chain and higher thermal stability hemicellulose can be obtained at optimal alkali concentration. An optimal alkali solution concentration was found to be at 1.5% KOH with the higher yield, xylose content and thermal stability of the hemicelluloses. NMR analysis showed that the alkaline extraction of the corn stalk with 1.5% KOH did not result in any obvious change in the macromolecular structure of hemicelluloses.
Effect of Ultrasonic-assisted Cold Caustic Extraction on the Properties of CTMP Poplar Fibers
Qianyu Sun,Guihua Yang,Jiachuan Chen,Ming He,Sipeng Niu 한국펄프·종이공학회 2017 펄프.종이技術 Vol.49 No.4
Chemithermo-mechanical pulp (CTMP) has been widely utilized in papermaking industry because of its high yield. However, the poor strength properties arising from the high contents of hemicellulose and lignin have limited its applications. In this study, ultrasonicassisted cold caustic extraction (CCE) on hemicellulose removal was applied to ascertain its influence on the properties of CTMP. It was found to have a positive effect on hemicellulose removal and resultant pulp properties. At the same alkali concentration (3 wt%), hemicellulose removal and Canadian Standard Freeness (CSF) in ultrasonic-assisted CCE (360 W, 10 min) increased 53.4% and 9.6%, respectively. Ultrasonic-assisted CCE reduces alkali concentration from 5 wt% to 2 wt% to obtain similar hemicelluloses removal, whereas the pulp yield at 2 wt% NaOH was higher than that of CCE alone at 5 wt% NaOH. In addition, at the same alkali concentration (3 wt%), the tensile index, bursting index and tearing index of CTMP in ultrasonic-assisted CCE (120 W, 10 min) increased by 12.7%, 11.34% and 3.0%, respectively. Ultrasonic-assisted CCE enhanced the fibrillation of fibers at optimal conditions, as determined by SEM.
Arrigoni Battaia, F.,Chen, Chian-Chou,Fumagalli, M.,Cai, Zheng,Calistro Rivera, G.,Xu, Jiachuan,Smail, I.,Prochaska, J. X.,Yang, Yujin,De Breuck, C. Springer-Verlag 2018 Astronomy and astrophysics Vol.620 No.-
<P>In the hierarchical model of structure formation, giant elliptical galaxies form through merging processes within the highest density peaks known as protoclusters. While high-redshift radio galaxies usually pinpoint the location of these environments, we have recently discovered at <I>z</I> ∼ 2−3 three enormous (> 200 kpc) Lyman-<I>α</I> nebulae (ELANe) that host multiple active galactic nuclei (AGN) and that are surrounded by overdensities of Lyman-<I>α</I> emitters (LAE). These regions are prime candidates for massive protoclusters in the early stages of assembly. To characterize the star-forming activity within these rare structures - both on ELAN and protocluster scales - we have initiated an observational campaign with the <I>James Clerk Maxwell</I> Telescope (JCMT) and the Atacama Pathfinder EXperiment (APEX) telescopes. In this paper we report on sensitive SCUBA-2/JCMT 850 and 450 <I>μ</I>m observations of a ∼128 arcmin<SUP>2</SUP> field comprising the ELAN MAMMOTH-1, together with the peak of the hosting BOSS1441 LAE overdensity at <I>z</I> = 2.32. These observations unveil 4.0 ± 1.3 times higher source counts at 850 <I>μ</I>m with respect to blank fields, likely confirming the presence of an overdensity also in obscured tracers. We find a strong detection at 850 <I>μ</I>m associated with the continuum source embedded within the ELAN MAMMOTH-1, which - together with the available data from the literature - allow us to constrain the spectral energy distribution of this source to be of an ultra-luminous infrared galaxy (ULIRG) with a far-infrared luminosity of LFIR<SUP>SF</SUP> = 2.4−2.1<SUP>+7.4</SUP>×10<SUP>12</SUP><I>L</I>⊙, and hosting an obscured AGN. Such a source is thus able to power a hard photoionization plus outflow scenario to explain the extended Lyman-<I>α</I>, He II<I>λ</I>1640, and C IV<I>λ</I>1549 emission, and their kinematics. In addition, the two brightest detections at 850 <I>μ</I>m (<I>f</I>850 > 18 mJy) sit at the density peak of the LAEs’ overdensity, likely pinpointing the core of the protocluster. Future multiwavelength and spectroscopic datasets targeting the full extent of the BOSS1441 overdensity have the potential to firmly characterize a cosmic nursery of giant elliptical galaxies, and ultimately of a massive cluster.</P>
Lu Yi,Wu Jiachuan,Hu Minhui,Zhong Qinghua,Er Limian,Shi Huihui,Cheng Weihui,Chen Ke,Liu Yuan,Qiu Bingfeng,Xu Qiancheng,Lai Guangshun,Wang Yufeng,Luo Yuxuan,Mu Jinbao,Zhang Wenjie,Zhi Min,Sun Jiachen 거트앤리버 소화기연관학회협의회 2023 Gut and Liver Vol.17 No.6
Background/Aims: The accuracy of endosonographers in diagnosing gastric subepithelial lesions (SELs) using endoscopic ultrasonography (EUS) is influenced by experience and subjectivity. Artificial intelligence (AI) has achieved remarkable development in this field. This study aimed to develop an AI-based EUS diagnostic model for the diagnosis of SELs, and evaluated its efficacy with external validation. Methods: We developed the EUS-AI model with ResNeSt50 using EUS images from two hospitals to predict the histopathology of the gastric SELs originating from muscularis propria. The diagnostic performance of the model was also validated using EUS images obtained from four other hospitals. Results: A total of 2,057 images from 367 patients (375 SELs) were chosen to build the models, and 914 images from 106 patients (108 SELs) were chosen for external validation. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the model for differentiating gastrointestinal stromal tumors (GISTs) and non-GISTs in the external validation sets by images were 82.01%, 68.22%, 86.77%, 59.86%, and 78.12%, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy in the external validation set by tumors were 83.75%, 71.43%, 89.33%, 60.61%, and 80.56%, respectively. The EUS-AI model showed better performance (especially specificity) than some endosonographers. The model helped improve the sensitivity, specificity, and accuracy of certain endosonographers. Conclusions: We developed an EUS-AI model to classify gastric SELs originating from muscularis propria into GISTs and non-GISTs with good accuracy. The model may help improve the diagnostic performance of endosonographers. Further work is required to develop a multi-modal EUS-AI system.
Preparation and Characterization of Cellulose Nanocrystals from Wheat Straw and Corn Stalk
Zhaoxiang Liu,Ming He,Guangrui Ma,Guihua Yang,Jiachuan Chen 한국펄프·종이공학회 2019 펄프.종이기술 Vol.51 No.2
Wheat straw and corn stalk are agricultural residues which are abundant, inexpensive, and readily available source of renewable lignocellulosic biomass. The aim of this study was to prepare cellulose nanocrystals (CNCs) from wheat straw and corn stalk, and to compare their characteristics. To achieve these goals, the CNCs obtained from hydrolysis were characterized in terms of physical, structural and morphological properties. Particle size distribution and atomic force microscopy (AFM) images showed that the CNC from corn stalk (CNC-CS) was more uniform than that from wheat straw (CNC-WS); FTIR spectra implied that acid hydrolysis treatment had no effect on the chemical structure of CNCs. Moreover, the crystallinity of CNC-CS was higher than that of CNC-WS and thermal stability of CNC-WS was observed to be similar to CNC-CS.