The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
Gye-chun Cho - One of the best experts on this subject based on the ideXlab platform.
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Water retention characteristics of biopolymer hydrogel containing sandy soils
Hue University Journal of Science: Earth Science and Environment, 2020Co-Authors: Thi Phuong An Tran, Gye-chun Cho, Chang IlhanAbstract:Microbial Biopolymers are introduced as a new soil binder which regarded to be environmentally-friendly materials in terms of low carbon emission and low impact on the soil ecosystem. In geotechnical engineering and agriculture, various gel-type materials have been used to improve the water absorbability of sandy soils, and control surface erosion. In this study, the soil-water characteristics of xanthan gum biopolymer-treated sand-clay mixtures are evaluated through a laboratory program using a soil-water characterization apparatus. Sand-clay mixtures are treated with different xanthan gum concentrations as 0% (untreated), 0.1%, 0.25%, 0.5%, 0.75% and 1.0%, to the mass of soil, respectively. Consequently, the xanthan gum-soil water characteristic curve results show the enhanced water holding capacity of soils with higher xanthan gum contents. The presence of xanthan gum hydrogels in the soil increases the initial and residual water contents. Biopolymers retain moisture loss from the soil, which makes the slope of the soil-water reduction curve to be more gradual.
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Soil water retention and vegetation survivability improvement using Microbial Biopolymers in drylands
Geomechanics and Engineering, 2019Co-Authors: An Thi Phuong Tran, Ilhan Chang, Gye-chun ChoAbstract:Vegetation cover plays a vital role in stabilizing the soil structure, thereby contributing to surface erosion control. Surface vegetation acts as a shelterbelt that controls the flow velocity and reduces the kinetic energy of the water near the soil surface, whereas vegetation roots reinforce the soil via the formation of root-particle interactions that reduce particle detachment. In this study, two vegetation-testing trials were conducted. The first trial was held on cool-season turfgrasses seeded in a biopolymer-treated site soil in an open greenhouse. At the end of the test, the most suitable grass type was suggested for the second vegetation test, which was conducted in an environmental control chamber. In the second test, Biopolymers, namely, starch and xanthan gum hydrogels (pure starch, pure xanthan gum, and xanthan gum-starch mixtures), were tested as soil conditioners for improving the water-holding capacity and vegetation growth in sandy soils. The results support the possibility that biopolymer treatments may enhance the survival rate of vegetation under severe drought environments, which could be applicable for soil stabilization in arid and semiarid regions.
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Shear strength behavior and parameters of Microbial gellan gum-treated soils: from sand to clay
Acta Geotechnica, 2018Co-Authors: Ilhan Chang, Gye-chun ChoAbstract:Microbial Biopolymers have recently been introduced as a new material for soil treatment and improvement. Biopolymers provide significant strengthening to soil, even in small quantities (i.e., at 1/10th or less of the required amount of conventional binders, such as cement). In particular, thermo-gelating Biopolymers, including agar gum, gellan gum, and xanthan gum, are known to strengthen soils noticeably, even under water-saturated conditions. However, an explicitly detailed examination of the microscopic interactions and strengthening characteristics between gellan gum and soil particles has not yet been performed. In this study, a series of laboratory experiments were performed to evaluate the effect of soil–gellan gum interactions on the strengthening behavior of gellan gum-treated soil mixtures (from sand to clay). The experimental results showed that the strengths of sand–clay mixtures were effectively increased by gellan gum treatment over those of pure sand or clay. The strengthening behavior is attributed to the conglomeration of fine particles as well as to the interconnection of fine and coarse particles, by gellan gum. Gellan gum treatment significantly improved not only inter-particle cohesion but also the friction angle of clay-containing soils.
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strength durability of gellan gum biopolymer treated korean sand with cyclic wetting and drying
Construction and Building Materials, 2017Co-Authors: Ilhan Chang, Seokwon Lee, Gye-chun ChoAbstract:Abstract Various biological approaches recently have been explored as alternative environmentally-friendly soil improvement strategies in the fields of construction and geotechnical engineering, with the aim of reducing the use of high greenhouse gas emitting construction binders such as cement. Previous studies have shown the effectiveness of Microbial Biopolymers in soil improvement. However, there are still concerns about the durability and serviceability of biopolymer treated soils, resulting from the biodegradation and hydrolysis behaviors of the biologically produced compounds. In this study, the strength and durability of gellan gum biopolymer treated Jumunjin sand (standard sand of the Republic of Korea) was evaluated under cyclic wetting and drying. The results obtained indicate that the cyclic wetting and drying of gellan gum-treated sands results in a gradual degradation of strength, due to the dissociation of the gellan gum monomers under wetting and imperfect recomposition during re-drying, with an approximately 30% strength reduction over 10 cycles. However, a certain degree of strength recovery and resistance was observed even after numerous cycles, indicating that gellan gum-treated soils can potentially be applied for temporary or medium-term purposes in practical construction.
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Soil treatment using Microbial Biopolymers for anti-desertification purposes
Geoderma, 2015Co-Authors: Ilhan Chang, Awlia Kharis Prasidhi, Hyun-dong Shin, Gye-chun ChoAbstract:Abstract Desertification and soil degradation are becoming more serious due to global warming and concurrent extreme climate events. Although anti-desertification efforts have been mounted worldwide, most undertakings have shown poor performance because of failure to consider soil and geotechnical aspects. Soil erosion is accelerated by reductions in soil cohesion and water retention due to the transfer of fine particles from the original ground. Thus, soil internal cohesion must be recovered to ensure effective and reliable anti-desertification attempts. In this study, soil treatment using Biopolymers is suggested as an alternative method to prevent soil erosion and for revitalization, taking into consideration engineering and environmental aspects. Even as a relatively small part of the soil mass (i.e., 0.5–1.0%), Biopolymers in soil have the positive potential to significantly reduce the erodibility of soil by enhancing inter-particle cohesion. Moreover, biopolymer treatment also improves both vegetation germination and soil water retention characteristics against evaporation, and therefore can provide suitable environments for plants and crops used as a desertification countermeasure in arid and semi-arid regions where annual precipitation is limited. We suggest combining Biopolymers with pre-existing anti-desertification efforts (e.g., afforestation and windbreaks) on desert fronts (i.e., boundaries between arid and semi-arid regions) for best efficiency.
Ilhan Chang - One of the best experts on this subject based on the ideXlab platform.
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Soil water retention and vegetation survivability improvement using Microbial Biopolymers in drylands
Geomechanics and Engineering, 2019Co-Authors: An Thi Phuong Tran, Ilhan Chang, Gye-chun ChoAbstract:Vegetation cover plays a vital role in stabilizing the soil structure, thereby contributing to surface erosion control. Surface vegetation acts as a shelterbelt that controls the flow velocity and reduces the kinetic energy of the water near the soil surface, whereas vegetation roots reinforce the soil via the formation of root-particle interactions that reduce particle detachment. In this study, two vegetation-testing trials were conducted. The first trial was held on cool-season turfgrasses seeded in a biopolymer-treated site soil in an open greenhouse. At the end of the test, the most suitable grass type was suggested for the second vegetation test, which was conducted in an environmental control chamber. In the second test, Biopolymers, namely, starch and xanthan gum hydrogels (pure starch, pure xanthan gum, and xanthan gum-starch mixtures), were tested as soil conditioners for improving the water-holding capacity and vegetation growth in sandy soils. The results support the possibility that biopolymer treatments may enhance the survival rate of vegetation under severe drought environments, which could be applicable for soil stabilization in arid and semiarid regions.
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Shear strength behavior and parameters of Microbial gellan gum-treated soils: from sand to clay
Acta Geotechnica, 2018Co-Authors: Ilhan Chang, Gye-chun ChoAbstract:Microbial Biopolymers have recently been introduced as a new material for soil treatment and improvement. Biopolymers provide significant strengthening to soil, even in small quantities (i.e., at 1/10th or less of the required amount of conventional binders, such as cement). In particular, thermo-gelating Biopolymers, including agar gum, gellan gum, and xanthan gum, are known to strengthen soils noticeably, even under water-saturated conditions. However, an explicitly detailed examination of the microscopic interactions and strengthening characteristics between gellan gum and soil particles has not yet been performed. In this study, a series of laboratory experiments were performed to evaluate the effect of soil–gellan gum interactions on the strengthening behavior of gellan gum-treated soil mixtures (from sand to clay). The experimental results showed that the strengths of sand–clay mixtures were effectively increased by gellan gum treatment over those of pure sand or clay. The strengthening behavior is attributed to the conglomeration of fine particles as well as to the interconnection of fine and coarse particles, by gellan gum. Gellan gum treatment significantly improved not only inter-particle cohesion but also the friction angle of clay-containing soils.
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strength durability of gellan gum biopolymer treated korean sand with cyclic wetting and drying
Construction and Building Materials, 2017Co-Authors: Ilhan Chang, Seokwon Lee, Gye-chun ChoAbstract:Abstract Various biological approaches recently have been explored as alternative environmentally-friendly soil improvement strategies in the fields of construction and geotechnical engineering, with the aim of reducing the use of high greenhouse gas emitting construction binders such as cement. Previous studies have shown the effectiveness of Microbial Biopolymers in soil improvement. However, there are still concerns about the durability and serviceability of biopolymer treated soils, resulting from the biodegradation and hydrolysis behaviors of the biologically produced compounds. In this study, the strength and durability of gellan gum biopolymer treated Jumunjin sand (standard sand of the Republic of Korea) was evaluated under cyclic wetting and drying. The results obtained indicate that the cyclic wetting and drying of gellan gum-treated sands results in a gradual degradation of strength, due to the dissociation of the gellan gum monomers under wetting and imperfect recomposition during re-drying, with an approximately 30% strength reduction over 10 cycles. However, a certain degree of strength recovery and resistance was observed even after numerous cycles, indicating that gellan gum-treated soils can potentially be applied for temporary or medium-term purposes in practical construction.
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Geotechnical shear behavior of Xanthan Gum biopolymer treated sand from direct shear testing
Geomechanics and Engineering, 2017Co-Authors: Sojeong Lee, Ilhan Chang, Moon-kyung Chung, Yunyoung Kim, Jong KeeAbstract:Conventional geotechnical engineering soil binders such as ordinary cement or lime have environmental issues in terms of sustainable development. Thus, environmentally friendly materials have attracted considerable interest in modern geotechnical engineering. Microbial Biopolymers are being actively developed in order to improve geotechnical engineering properties such as aggregate stability, strength, and hydraulic conductivity of various soil types. This study evaluates the geotechnical engineering shear behavior of sand treated with xanthan gum biopolymer through laboratory direct shear testing. Xanthan gum-sand mixtures with various xanthan gum content (percent to the mass of sand) and gel phases (initial, dried, and re-submerged) were considered. Xanthan gum content of 1.0% sufficiently improves the inter-particle cohesion of cohesionless sands 3.8 times and more (up to 14 times for dried state) than in the untreated (natural) condition, regardless of the xanthan gum gel condition. In general, the strength of xanthan gum-treated sand shows dependency with the rheology and phase of xanthan gum gels in inter-granular pores, which decreases in order as dried (biofilm state), initial (uniform hydrogel), and re-submerged (swollen hydrogel after drying) states. As xanthan gum hydrogels are pseudo-plastic, both inter-particle friction angle and cohesion of xanthan gum-treated sand decrease with water adsorbed swelling at large strain levels. However, for 2% xanthan gum-treated sands, the re-submerged state shows a higher strength than the initial state due to the gradual and non-uniform swelling behavior of highly concentrated biofilms.
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introduction of Microbial Biopolymers in soil treatment for future environmentally friendly and sustainable geotechnical engineering
Sustainability, 2016Co-Authors: Ilhan Chang, Jooyoung ImAbstract:Soil treatment and improvement is commonly performed in the field of geotechnical engineering. Methods and materials to achieve this such as soil stabilization and mixing with cementitious binders have been utilized in engineered soil applications since the beginning of human civilization. Demand for environment-friendly and sustainable alternatives is currently rising. Since cement, the most commonly applied and effective soil treatment material, is responsible for heavy greenhouse gas emissions, alternatives such as geosynthetics, chemical polymers, geopolymers, Microbial induction, and Biopolymers are being actively studied. This study provides an overall review of the recent applications of Biopolymers in geotechnical engineering. Biopolymers are Microbially induced polymers that are high-tensile, innocuous, and eco-friendly. Soil–biopolymer interactions and related soil strengthening mechanisms are discussed in the context of recent experimental and microscopic studies. In addition, the economic feasibility of biopolymer implementation in the field is analyzed in comparison to ordinary cement, from environmental perspectives. Findings from this study demonstrate that Biopolymers have strong potential to replace cement as a soil treatment material within the context of environment-friendly construction and development. Moreover, continuing research is suggested to ensure performance in terms of practical implementation, reliability, and durability of in situ biopolymer applications for geotechnical engineering purposes.
Argyrios Margaritis - One of the best experts on this subject based on the ideXlab platform.
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Empirical modeling of batch fermentation kinetics for poly(glutamic acid) production and other Microbial Biopolymers
Biotechnology and bioengineering, 2004Co-Authors: Andrew Richard, Argyrios MargaritisAbstract:An empirical kinetic model is proposed for the batch production of poly(glutamic acid) from Bacillus subtilis IFO 3335. In addition, the proposed model was used to fit the kinetic data of poly(glutamic acid) production from other bacterial strains using different media, as well as kinetic data from different strains for the production of the exocellular Biopolymers dextran, hyaluronic acid, xanthan, alginate, and the endocellular biopolymer polyhydroxybutyrate. The empirical model treats the biopolymer as a component of the biomass and fits the experimental biomass data using a sigmoidal relationship that includes the maximum specific growth rate, mu(max), and the substrate saturation parameter, K(S). An empirical parameter, the relative coefficient (r), quantifies, in relative terms, the degree of nongrowth-associated biopolymer formation.
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Production and Mass Transfer Characteristics of Non-Newtonian Biopolymers for Biomedical Applications
Critical reviews in biotechnology, 2002Co-Authors: Andrew Richard, Argyrios MargaritisAbstract:The market for Microbial Biopolymers is currently expanding to include several emerging biomedical applications. Specifically, these applications are drug delivery and wound healing. A fundamental understanding of the key fermentation parameters is necessary in order to optimize the production of these Biopolymers. Considering that most Microbial biopolymer systems exhibit non-Newtonian rheology, oxygen mass transfer can be an important parameter to optimize and control. In this article, we present a critical review of recent advances in rheological and mass transfer characteristics of selected Biopolymers of commercial interest in biomedical applications.
T Vendruscoloclaire - One of the best experts on this subject based on the ideXlab platform.
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Poly(3-hydroxybutyrate)-P(3HB): Review of Production Process Technology
Industrial Biotechnology, 2017Co-Authors: I Alvesmariane, L Macagnankarine, A Rodriguesamanda, A De Assisdener, M Torresmatheus, D De Oliveirapatrícia, Furlanlígia, T VendruscoloclaireAbstract:Abstract For decades, conventional plastics obtained from fossil-based sources have been used indiscriminately due to their durability and resistance. However, their use is problematic because of their rapid disposability and slow degradation. Growing scientific interest in the environmental issues associated with rising plastics consumption has become of increasing importance in the search for biodegradable substitutes. Poly (3-hydroxybutyrate) (P(3HB)) is one of the most studied and characterized Microbial Biopolymers from the family of polyhydroxyalkanoates (PHAs). Its main features are rapid biodegradability, low toxicity, and biocompatibility. Global production of PHAs is approximately 100 tons/year, and is expected to grow to 500,000 tons/year by 2020. Researchers have sought to increase the intracellular accumulation and polymer yield of PHAs by screening strains and improving the cultivation and operating procedures employed during the production processes. Synthesis of P(3HB) normally involves tw...
Seokwon Lee - One of the best experts on this subject based on the ideXlab platform.
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strength durability of gellan gum biopolymer treated korean sand with cyclic wetting and drying
Construction and Building Materials, 2017Co-Authors: Ilhan Chang, Seokwon Lee, Gye-chun ChoAbstract:Abstract Various biological approaches recently have been explored as alternative environmentally-friendly soil improvement strategies in the fields of construction and geotechnical engineering, with the aim of reducing the use of high greenhouse gas emitting construction binders such as cement. Previous studies have shown the effectiveness of Microbial Biopolymers in soil improvement. However, there are still concerns about the durability and serviceability of biopolymer treated soils, resulting from the biodegradation and hydrolysis behaviors of the biologically produced compounds. In this study, the strength and durability of gellan gum biopolymer treated Jumunjin sand (standard sand of the Republic of Korea) was evaluated under cyclic wetting and drying. The results obtained indicate that the cyclic wetting and drying of gellan gum-treated sands results in a gradual degradation of strength, due to the dissociation of the gellan gum monomers under wetting and imperfect recomposition during re-drying, with an approximately 30% strength reduction over 10 cycles. However, a certain degree of strength recovery and resistance was observed even after numerous cycles, indicating that gellan gum-treated soils can potentially be applied for temporary or medium-term purposes in practical construction.