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Interactions between metal ions and the biopolymer in activated sludge: quantification and effects of

Yun Zhou, Siqing Xia, Binh T. Nguyen, Min Long, Jiao Zhang, Zhiqiang Zhang

《环境科学与工程前沿（英文）》 2017年第11卷第1期 doi: 10.1007/s11783-017-0898-6

摘要： The biopolymer showed two protein-like fluorescence peaks (peaks A and B). Interactions of Pb(II) and biopolymer were quantified at various system pH values. System pH values significantly affect the quenching constant values for both peaks. Peak B plays a more important role in the interactions than peak A. Removal mechanism of metal ions by activated sludge system was further disclosed. The quantification and effects of system pH value on the interactions between Pb(II) and the biopolymer from activated sludge were investigated. The biopolymer had two protein-like fluorescence peaks (Ex/Em= 280 nm/326–338 nm for peak A; Ex/Em= 220–230 nm/324–338 nm for peak B). The fluorescence intensities of peak B were higher than those of peak A. The fluorophores of both peaks could be largely quenched by Pb(II), and the quencher dose for peak B was about half of that for peak A. The modified Stern-Volmer equation well depicted the fluorescence quenching titration. The quenching constant (Ka) values for both peaks decreased with rising system pH value, and then sharply decreased under alkaline conditions. It could be attributed to that the alkaline conditions caused the reduction of available Pb(II) due to the occurrence of Pb(OH)2 sediments. The Ka values of peak B were bigger than those for peak A at the same system pH values. Accordingly, the aromatic protein (peak B) plays the key role in the interactions between metal ions and the biopolymer.

关键词： Metal ions Biopolymer Activated sludge Three-dimensional excitation emission matrix (3D-EEM) Fluorescence regional integration (FRI) technique Quantification

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Biopolymer-stabilized emulsions on the basis of interactions between β -lactoglobulin and ι -carrageenan

Qiaomei RU, Younghee CHO, Qingrong HUANG,

《化学科学与工程前沿（英文）》 2009年第3卷第4期页码 399-406 doi: 10.1007/s11705-009-0253-y

摘要： -Carrageenan and -lactoglobulin (-lg) stabilized oil-in-water (O/W) emulsions, which can be used for the oral administration of bioactive but environmentally sensitive ingredients, have been successfully prepared. The effects of protein/polysaccharide ratios, total biopolymer concentration, environmental stress (thermal processing and sonication), and pH on the complex formation between -carrageenan and -lactoglobulin have been investigated. We found that -lactoglobulin and-carrageenan stabilized emulsions can be formed at pH values of 6.0, 4.0, and 3.4. However, the microstructures of emulsions stabilized by -lactoglobulin and -carrageenan was identified by optical microscopy, and it indicated that the emulsion prepared at pH 6.0 flocculated more extensively, while its hydrodynamic radius was much bigger than those prepared at pH 4.0 and 3.4. Regarding rheological properties, the emulsion of pH 6.0 showed a more solid-like behavior but with a lower viscosity than those of pH 4.0 and 3.4. The optimum concentration ranges for -lg and-carrageenan to form stable emulsions at pH 4.0 and 3.4 were 0.3wt-%―0.6wt-% and 0.4wt-%―0.7wt-%, respectively.

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Moisture diffusion behavior of permeable fiber-reinforced polymer composite

Jianjiang YANG, Qingsheng YANG, Lianhua MA, Wei LIU,

《机械工程前沿（英文）》 2010年第5卷第3期页码 347-352 doi: 10.1007/s11465-010-0093-y

摘要： A unit cell approach is employed to predict the effective moisture diffusion property in fiber-reinforced biopolymer. The permeable fibers distributed in the matrix are taken as inclusion phases in the system. Based on a unit cell model, the calculation method for moisture diffusion coefficients is developed in this paper. Moisture diffusion property and effective diffusion coefficients are numerically investigated under different temperature and volume fractions of fibers. The calculated results agree well with Gueribiz’s solutions. Therefore, it is reliable in predicting moisture diffusion property of composite using the unit cell model. The present result shows that the effective diffusion coefficient of a composite depends on both temperature and volume fraction of fibers. The effective diffusion coefficient of regular hexagon pattern composite is larger than that of square pattern at the same temperature and volume fraction.

关键词： fiber-reinforced biopolymer effective diffusion coefficient unit cell finite element modeling (FEM)

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Advancements in non-starch polysaccharides research for frozen foods and microencapsulation of probiotics

Pavan Kumar SOMA, Patrick D. WILLIAMS, Y. Martin LO,

《化学科学与工程前沿（英文）》 2009年第3卷第4期页码 413-426 doi: 10.1007/s11705-009-0254-x

摘要： Conventionally used in the food industry as stabilizing, thickening, gelling, and suspending or dispersing agents, non-starch polysaccharides such as xanthan gum are known to improve the texture of certain frozen products. Another polysaccharide that has received significant attention in recent years is chitosan, a natural biopolymer derived from chitin. In the wake of growing interest in finding ideal encapsulating agents for probiotics, non-starch polysaccharides have been investigated. Scattered research can be found on the effect of each individual polysaccharide, but there remains a void in the literature in terms of closely comparing the characteristics of non-starch polysaccharides for these applications, especially when more than one biopolymer is employed. A good understanding of the tools capable of elucidating the underlying mechanisms involved is essential in ushering further development of their applications. Therefore, it is this review’s intention to focus on the selection criteria of non-starch polysaccharides based on their rheological properties, resistance to harsh conditions, and ability to improve sensory quality. A variety of critical tools is also carefully examined with respect to the attainable information crucial to frozen food and microencapsulation applications.

关键词： development literature attainable information biopolymer capable

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Progress of three-dimensional macroporous bioactive glass for bone regeneration

Lijun JI, Yunfeng SI, Ailing LI, Wenjun WANG, Dong QIU, Aiping ZHU

《化学科学与工程前沿（英文）》 2012年第6卷第4期页码 470-483 doi: 10.1007/s11705-012-1217-1

摘要： Bioactive glasses (BGs) are ideal materials for macroporous scaffolds due to their excellent osteoconductive, osteoinductive, biocompatible and biodegradable properties, and their high bone bonding rates. Macroporous scaffolds made from BGs are in high demand for bone regeneration because they can stimulate vascularized bone ingrowth and they enhance bonding between scaffolds and surrounding tissues. Engineering BG/biopolymers (BP) composites or hybrids may be a good way to prepare macroporous scaffolds with excellent properties. This paper summarizes the progress in the past few years in preparing three-dimensional macroporous BG and BG/BP scaffolds for bone regeneration. Since the brittleness of BGs is a major problem in developing macroporous scaffolds and this limits their use in load bearing applications, the mechanical properties of macroporous scaffolds are particularly emphasized in this review.

关键词： bioactive glass biopolymer bone regeneration macroporous scaffolds tissue engineering