CANADIAN METALLURGICAL QUARTERLY
·
2023
·
IF 0.9
Lei He,Jiahao Liu,Tu Hu,Tingting Lv,Li Gao
The critical factor for smooth slag discharge has been found to be the viscosity characteristics of the molten slag. Molten slag cannot reach the condition for slag trapping owing to its high Fe2O3 contents. In the process of high temperature oxidation melting, the influence of Fe2O3 contents on molten slag viscosity behaviour is not clear. Therefore, the effect of Fe2O3 contents on molten slag viscosity-temperature behaviour was studied in the paper. With the Fe2O3 contents increased, at constant temperature, the molten slag viscosity was found to decrease. In addition, a linear relationship was established between lnη and 1/RT at elevated temperatures. The molten slag structure has been characterised to show that the degree of polymerisation decreases with increasing Fe2O3 contents. The calculated Λ, NBO/T and Q were also consistent with Raman analysis. This suggested that Fe2O3 contents affected the molten slag structure, resulting in the changes of molten slag viscosity. In the cooling process, as the increasing Fe2O3 ratio, the tendency of crystallization is enhanced. In short, molten slag viscosity and crystallization behaviour can be changed by controlling Fe2O3 contents. These findings could provide a guidance for adjusting Fe2O3 contents to improve the molten slag viscosity behaviour.Effets de la teneur en Fe2O3 sur le comportement de la viscosité des scories fondues Il a été constaté que le facteur critique pour une évacuation sans accroc des scories réside dans les caractéristiques de viscosité des scories fondues. Les scories fondues ne peuvent pas atteindre les conditions de piégeage des scories en raison de leur teneur élevée en Fe2O3. Dans le procédé de fusion par oxydation à haute température, l’influence de la teneur en Fe2O3 sur le comportement de la viscosité des scories fondues n’est pas claire. Par conséquent, il est d’une grande importance d’explorer l’influence de la teneur en Fe2O3 sur le comportement de la viscosité des scories fondues. Dans l’article, on a étudié l’effet de la teneur en Fe2O3 sur le comportement viscosité-température des scories fondues. Avec l’augmentation de la teneur en Fe2O3, à température constante, la viscosité des scories fondues diminue. De plus, on a établi une relation linéaire entre lnη et 1/RT à hautes températures. On a caractérisé la structure des scories fondues pour montrer que le degré de polymérisation diminue avec l’augmentation de la teneur en Fe2O3. Les valeurs Λ, NBO/T et Q calculées étaient également en accord avec l’analyse Raman. Cela suggère que la teneur en Fe2O3 affecte la structure des scories fondues, ayant pour résultat des changements dans la viscosité des scories fondues. Dans le procédé de refroidissement, avec l’augmentation du rapport de Fe2O3, la tendance à la cristallisation est renforcée. En bref, on peut modifier la viscosité des scories fondues et leur comportement de cristallisation en contrôlant la teneur en Fe2O3. Ces résultats pourraient fournir une orientation pour ajuster la teneur en Fe2O3 afin d’améliorer le comportement de la viscosité des scories fondues.
研究领域:
冶金学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FOOD CHEMISTRY
·
2018
·
IF 4.946
Zhen Qin,Qiming Chen,Si Lin,Sa Luo,Yongjun Qiu,Liming Zhao
Chitooligosaccharide is widely used as a functional food additive and a valuable pharmacological agent. The transformation of chitinous biomass into valuable bioactive chitooligosaccharides is one of the most exciting applications of chitosanase. A novel glycoside hydrolase (GH) family 46 chitosanase (GsCsn46A) from rhizobacterium Gynuella sunshinyii was cloned and heterologously expressed in Escherichia coli . GsCsn46A showed maximal activity at pH 5.5 and 30 °C. GsCsn46A featured remarkable cold-adapted property, which controllably hydrolyzed chitosan to three types of chitooligosaccharides at the mild reaction condition (reaction condition: pH 5.5 at 30 °C; method for stopping the reaction: 50 °C for 30 min). The yields of three types of chitooligosaccharides products (degree of polymerization (DP): 2–7, 2–5 and 2–3) were 70.9%, 87.1% and 94.6% respectively. This novel cold-adapted chitosanase provides a cleaner production process for the controllable preparation of chitooligosaccharides with the specific DP.
研究领域:
生物化学
·
酶工程
·
食品科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
STEEL RESEARCH INTERNATIONAL
·
2024
·
IF 1.9
Li Zhang,Hang He,Lei Zhang,Yongqi Sun,Xu Gao,Jie Zeng,Wanlin Wang
Viscosity is an important property for CaO-SiO 2 -Al 2 O 3 -based slag systems, which showcases different scenarios in basic and acid slag systems with temperature change. This article elucidates the mechanism of their difference in viscosity–temperature property from melt structure. Results reveal that basic slag shows a low degree of polymerization (DOP) and a low viscosity of the melt due to an excessive O 2− ions depolymerizing the complex network structures, resulting in more low-polymerized Q 0 (Si) units and less high-polymerized Q 3 (Si) units. With the temperature decreases, the DOP and viscosity do not change significantly. However, the low DOP and viscosity favor crystal precipitation in the melt, leading to a solid–liquid mixed state of the slag, and thus a sharp increase in viscosity when the temperature decreases to 1275 °C. For acid slag, it undergoes a transformation into aluminosilicate structures with the introduction of numerous [AlO 4 ] 5− tetrahedra, accompanied by a significant increase in the relative mole fraction of high-polymerized Q 3 (Si) units. Consequently, the DOP and viscosity are obviously higher than that of the basic slag. Furthermore, the DOP and viscosity of the acid slag increase continuously with the temperature decreasing, thus impeding crystal precipitation and enhancing the glass transition tendency of the molten slag.
研究领域:
材料科学
·
冶金学
✓ 已验证
DOI
高影响因子
CELLULOSE
·
2025
·
IF 4.8
Zhao Yao,Wang Xueping,Li Bowen,Si Tian,Gao Xin,Peng Lincai,Zhang Heng
The cellulose catalytic oxidation system mainly comprises inorganic ion-based oxidants. Hence, the selective oxidation of C 6- primary hydroxy groups (C 6 -OH) of cellulose, catalyzed by piperidine free radicals, was limited to the homogeneous cellulosic system containing protic solvents or heterogeneous system. In this work, the use of the catalytic system containing 4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl (4-AcNH-TEMPO) was extended to the cellulosic solution in N, N-dimethylacetamide (DMAc) and combined with chlorine dioxide. Results showed that the carboxyl content was 0.832 mmol/g. Meanwhile, the degree of polymerization decreased from 900 to 489. This study provides an effective route for the homogeneous selective oxidation of primary hydroxy groups in cellulose and explored its oxidation mechanism in DMAc solvent. Furthermore, studies showed that the reactive chlorine species- ClO·, Cl·, and ClO 2 played a crucial role in the oxidation process. The methodology developed here displayed great potential to be utilized to various biomolecules in aprotic solvents homogeneous system based on 4-AcNH-TEMPO as oxidation catalysts.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FIBERS AND POLYMERS
·
2018
·Vol. 19
·期 5
·1128-1134
·
IF 1.353
Chen Yanhua,Teng Na,Chen Haizhen,Chen Jing,Liu Fei,Na Haining,Zhu Jin
Electrospinnability as well as dissolvability of the celluloses derived from different biomass resources are systematically studied in this work. By analyzing the essentially physical and molecular structure of cellulose in detail, dissolving efficiency and molecular chain entanglement in solution of cellulose are carefully realized. Accordingly, the original factors on electrospinnability of cellulose is revealed. Crystallinity mainly affects the dissolution of cellulose, which is the foundation to achieve electrospinning. Degree of polymerization is the decisive index of cellulose to form molecular entanglement in solution or not. Proper molecular entanglement of cellulose, just as corn cellulose II, could initiate the formation of ultrafine fiber with good morphology in electrospinning. Our research is no doubt helpful to establish a solid scientific and technical foundation for selection of cellulose to achieve high efficiency fabrication of ultrafine fiber in electrospinning.
研究领域:
材料科学
·
生物化学
✓ 已验证
产品关联
DOI
高影响因子
GREEN CHEMISTRY
·
2024
·
IF 9.3
Runzhu Gong,Chao Liu,Meiyan Wu,Rui Tian,Guang Yu,Xitao Luo,Bin Li,Feng Peng,Yanjun Tang
Renewable hemicellulose with a unique structure exhibits a wide range of potential applications. However, it has been a formidable challenge to isolate hemicellulose with an intact structure from lignocellulosic materials. In this study, LiBr·3H2O (LBTH) was used as a green solvent for the effective fractionation of hemicellulose from bleached hardwood kraft pulp (BHKP) under mild conditions (25–85 °C). It was found that hemicellulose in BHKP can be dissolved in LBTH with ease and high selectivity owing to the breaking of hydrogen bonds between hemicellulose and cellulose, and the dissolved hemicellulose can be regenerated with a high degree of polymerization (DP) in the range of 240–264 using ethanol precipitation. The highest removal rate of hemicellulose from BHKP was as high as 95.2%, and the corresponding yield of pure hemicellulose reached 84.3%. Moreover, simultaneously obtained undissolved cellulose pulp through LBTH treatment had a high content of α-cellulose (96.7%), high DP (880), and trace levels of Fe (2 ppm), which met the standard requirement for dissolving pulp for the production of lyocell. In addition, LBTH can be easily recycled to guarantee a green and sustainable process. This work provides a new approach for highly selective fractionation of hemicellulose and cellulose from commercial BHKP based on an efficient and environmentally friendly LBTH treatment, which could be very promising for better valorization of hemicellulose and cellulose in many advanced applications.
研究领域:
林业科学
·
材料科学
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
FIBERS AND POLYMERS
·
2011
·Vol. 12
·期 3
·345-351
·
IF 0.84
Li Chaorong,Chen Rui,Zhang Xiaoqiang,Xiong Jie,Zheng Yingying,Dong Wenjun
Nanofibers of natural cotton lines cellulose, with a degree of polymerization above 10000, were prepared by electrospinning. The effects of cellulose concentration, flow rate and electric field strength on the morphologies of the fibers were systematically investigated. Furthermore, two effective improvements on the electrospinning apparatus were made: heating the pathway between the tip of the needle and the collector instead of the needle or the collector, and covering the drum with activated cellulose flake. High quality cellulose nanofibers were obtained under the optimized spinning conditions combined with the apparatus improvements. Moreover, oriented cotton nanofibers were acquired by elevating the rotation speed of the drum collector. The wettability of the nonwoven was greatly improved compared with the original activated cellulose. The obtained nonwoven or nanofibers of the natural cotton cellulose could be potentially applied in tissue scaffolds, protective clothing and high efficient water absorbing materials etc.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2024
·
IF 10.7
Yi Zhao,Juan Wang,Rui He,Yuanyuan Ren,Jin Fu,Yunjun Zeng,Kangyi Zhang,Geng Zhong
This study investigated the influence of Konjac Glucomannan (KGM) with varying degrees of polymerization (DKGMx) on the gelatinization and retrogradation characteristics of wheat starch, providing new insights into starch-polysaccharide interactions. This research uniquely focuses on the effects of DKGMx, utilizing multidisciplinary approaches including Rapid Visco Analysis (RVA), Differential Scanning Calorimetry (DSC), rheological testing, Low-Field Nuclear Magnetic Resonance (LF-NMR), and molecular simulations to assess the effects of DKGMx on gelatinization temperature, viscosity, structural changes post-retrogradation, and molecular interactions. Our findings revealed that higher degrees of polymerization (DP) of DKGMx significantly enhanced starch's pasting viscosity and stability, whereas lower DP reduced viscosity and interfered with retrogradation. High DP DKGMx promoted retrogradation by modifying moisture distribution. Molecular simulations revealed the interplay between low DP DKGMx and starch molecules. These interactions, characterized by increased hydrogen bonds and tighter binding to more starch chains, inhibited starch molecular rearrangement. Specifically, low DP DKGMx established a dense hydrogen bond network with starch, significantly restricting molecular mobility and rearrangement. This study provides new insights into the role of the DP of DKGMx in modulating wheat starch's properties, offering valuable implications for the functional improvement of starch-based foods and advancing starch science.
研究领域:
食品科学
·
分子生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2022
·
IF 6.364
Qiankun Xu,Qingliang Shan,Jianbao Hu,Yewei Wang,Yu Wang,Qian Ma,Changrong Chen,Yuqian Zhou,Anze Shui
The oxidation property of SiC-B 4 C- x Al 2 O 3 ( x ranges from 0 wt% to 30 wt%) ceramics was studied in air at 1400 ℃. Results show that the porous oxide layer becomes dense and smooth with addition of Al 2 O 3 . When the content of Al 2 O 3 is proper, the DOP (degree of polymerization) of borosilicate network can be improved with increase of Al 2 O 3 content, inhibiting the migration of atoms and molecular groups. With that, the crystallization of SiO 2 and volatilization of B 2 O 3 can be restrained. When the content of Al 2 O 3 is excessive, the DOP of borosilicate network will be decreased, deteriorating the oxide layer morphology. It is believed that the damage of borosilicate network by excess Al 2 O 3 should be responsible for this phenomenon. In this research, the SiC-B 4 C ceramic with optimal oxidation resistant can be obtained when the content of Al 2 O 3 is 15 wt%.
研究领域:
材料科学
·
无机非金属材料
·
高温材料
·
表面工程
·
陶瓷学
✓ 已验证
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2020
·Vol. 138
·期 10
·49971
·
IF 2.52
Xinqiu Hong,Yongjing Xu,Liming Zou,Yan Vivian Li,Junwei He,Jiongxin Zhao
Polyvinyl alcohol (PVA) fibers were prepared using PVA with different degree of polymerization (DP) under the same wet spinning process. The effect of the DP of PVA on the structures and properties of PVA and PVA fibers were studied by using nuclear magnetic resonance hydrogen spectroscopy ( 1 H-NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermo gravimetric analysis (TGA), and environmental scanning electron microscope (ESEM). The results showed that DP had little effect on the crystallinity and tacticity of PVA, but had a positive effect on melting temperature, and initial decomposition temperature of PVAs. The hot drawing ratio determined by the spinning process where the PVA fibers could be continuously collected without breaking. The drawing ratio was decreased with an increase of DP, resulting in an increase of the final fiber diameter. The PVA fibers with medium DP and medium size demonstrated high strength and high modulus, but relatively low breaking elongation. It suggested that high DP of PVA was not a guarantee of high strength and high modulus PVA fibers, but rather a primary structure factor. The fiber performance was determined by a comprehensive effect combining a variety of factors including polymer properties and spinning conditions. It provided a guideline for PVA fiber manufacture that the PVAs with different DP require different spinning processes to obtain optimal fiber performance.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2019
·
IF 6.044
Hangyan Ji,Yuxiang Bai,XiaoXiao Li,Jinpeng Wang,Xueming Xu,Zhengyu Jin
An open reading frame from Palaeococcus pacificus was discovered by genomic analysis. The recombinant PpCD was proved as novel extremely thermal-stable cyclodextrinase with potential on production of malto-oligosaccharides with specific degree of polymerization. This enzyme has extremely high substrate specificity toward cyclodextrins, while the rates of hydrolysis toward macromolecular or linear substrates such as starch, pullulan and amylose were pretty slow. The optimal pH and temperature of PpCD were determined as 6.0 and 95 °C respectively. It was confirmed that PpCD could produce malto-oligosaccharides with a certain degree of polymerization in consistent with that of cyclodextrin substrates. In this study, the preparation of high purity maltoheptaose was achieved and the suitable β-cyclodextrin concentration was about 8–10%. Therefore, PpCD may have a potential application in the production of specific degree of polymerization malto-oligosaccharides.
研究领域:
生物化学
·
酶工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MOLECULES
·
2018
·Vol. 23
·期 11
·2891
·
IF 3.098
Xiao Chen,Jia Xiong,Shenlin Huang,Xun Li,Yu Zhang,Liping Zhang,Fei Wang
The proanthocyanidins from ethanol extracts (80%,v/v) ofAcacia mearnsii(A. mearnsii) bark on chemical-based and cellular antioxidant activity assays as well as carbolytic enzyme inhibitory activities were studied. About 77% of oligomeric proanthocyanidins in ethanol extracts ofA. mearnsiibark were found by using normal-phase HPLC. In addition, HPLC-ESI-TOF/MS and MALDI-TOF/TOF MS analyses indicated that proanthocyanidins fromA. mearnsiibark exhibited with a degree of polymerization ranging from 1 to 11. These results of combined antioxidant activity assays, as well as carbolytic enzyme inhibitory activities of proanthocyanidins fromA. mearnsiibark, indicated an encouraging antioxidant capacity for the high polyphenol content and a potential for use as alternative drugs for lowering the glycemic response.Keywords:proanthocyanidins;HPLC/MS;MALDI-TOF/MS;antidiabetic;antioxidant;degree of polymerization
研究领域:
药理学
·
生物化学
·
分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）