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Bioremediation Research in EPA: An Overview of Needs, Directions, and Potentials
Published in Robert F. Hickey, Gretchen Smith, Biotechnology in Industrial Waste Treatment and Bioremediation, 2020
P. H. Pritchard, J. E. Lin, J. G. Mueller, M. S. Shields
Work at the EPA Gulf Breeze Laboratory has demonstrated the potential usefulness of encapsulation in the bioremediation of PAHs. A model system has been developed in which a pure culture capable of degrading phenanthrene has been successfully encapsulated in the polymeric material, polyvinyl alcohol.17 The capsules can be stored for several months at 4°C with minimal loss of viability. Upon addition of the capsules to moist soil, the bacteria are released (the capsule dissolves when wetted) and phenanthrene mineralization commenced in approximately the same way as that observed when adding fresh bacterial cells to soil. These results are shown in Figure 2. In addition, if the capsules also contain a growth substrate, the released organisms will grow and actually increase the phenanthrene mineralization rates. The release of cells and nutrients can be controlled by the addition of water and by the use of polyvinyl alcohol polymers of different molecular weight.
Microencapsulation Technology and Future Trends
Published in Chester L. Foy, David W. Pritchard, and Adjuvant Technology, 2018
Alan J. Stern, David Z. Becher
This is probably the second most used technology for pesticides. Many of the comments made above for interfacial polymerization also apply to this technology. There have been a number of interesting advances in this area. For example, Scher and Rodson have disclosed a novel twist on the standard urea-formaldehyde in situ polymerization method of encapsulation.41–43 In this case, the urea-formaldehyde prepolymer is 50 to 98% etherified with a C-4 to C-10 alcohol, making it soluble in the oil phase. Because of this, the polymerization takes place inside the dispersed oil droplet rather than in the continuous aqueous phase. This has several advantages including the ability to produce a higher concentration of capsules in the formulation.
The Role of Polymers in Solid Oral Dosage Forms
Published in Ijeoma F. Uchegbu, Andreas G. Schätzlein, Polymers in Drug Delivery, 2006
Richard A. Kendall, Abdul W. Basit
Capsules are used as an alternative to tablets, for poorly compressible materials, to mask the bitter taste of certain drugs, or sometimes to increase bioavailability. Many of the polymeric excipients used to “bulk out” capsule fills are the same as those used in immediate-release tablets. Gelatin has been used almost exclusively since the 1830s as a shell material for hard (two-piece) and soft (one-piece) capsules. This is due in part to its ready availability but primarily because of its near-to-ideal physicochemical properties for the encapsulation of solid and semisolid material, that is, its ability to form thin but tough and flexible films that gel at an appropriate temperature, and remain stable over long-term storage but dissolve readily in biological fluids at 37°C. As a further advantage, gelatin being odorless and tasteless is acceptable to most palates.
Effect of rejuvenating oil type on the synthesis and properties of alginate-based polynuclear capsules for asphalt self-healing
Published in Road Materials and Pavement Design, 2023
Jose L. Concha, Luis E. Arteaga-Pérez, Erik Alpizar-Reyes, Cristina Segura, Irene Gonzalez-Torre, Antonios Kanellopoulos, Jose Norambuena-Contreras
Capsules were synthesised using the microfluidic pressure pump method (see Figure 4), recently published by Norambuena-Contreras et al. (2020, 2021). The method is based on the ionic gelation of sodium alginate in the presence of calcium ions (Zhang et al., 2016), and it has the following steps: first, the ionic crosslinker was prepared by adding 5% w/w of calcium-chloride (CaCl2) into deionised water. Then, a 60 mL syringe containing the fresh O/W emulsion (i.e. VCO, WCO, or VEO emulsion) was placed in an automatic syringe pump (New Era NE-1010, Farmingdale, NY, USA) operated at 2 mL/min. The capsules were formed by letting the outgoing emulsion drop into the CaCl2 crosslinking solution, continuously stirred at 250 rpm. Calcium ions diffuse in the O/W emulsion, promoting crosslinking on the solution-emulsion interface, resulting in the well-known calcium-alginate ‘egg-box' complex (Ca-alginate). Once the encapsulation process was completed, the capsules were maintained in the crosslinking solution for 30 min. Following this resting period, the capsules were separated from the solution by filtering; then, they were rinsed with 300 mL of deionised water, and after that, they were oven-dried for 24 h at 35°C. Finally, the capsules were placed into a vial and stored in a freezer at −18°C to avoid the oxidation of the encapsulated rejuvenating agents.
Mathematical modelling of drug-diffusion from multi-layered capsules/tablets and other drug delivery devices
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
In the past recent years, various innovations are adopted to structure and construct layer-by-layer spherical capsules and cylindrical tablets (Kaoui et al. 2018), to make the drug application effective and to deliver the required drug dose to the target site in a more productive manner. To understand the dynamics of drug release and control, a mathematical model has been devised to estimate the drug release and diffusion from the multi-layered capsules/tablets. Usually, a capsule consists of a drug-loaded (fluid or solid) core surrounded by one or more hydrogel layers. This type of encapsulation having multi-layers increases the capsule’s mechanical stability, its bioavailability, shields the active ingredients from external chemical aggression and premature degradation and enhances the imperishable drug release (McGinty and Pontrelli 2015; Kaoui et al. 2018; Carr and Pontrelli 2018, 2019).
A systematic review on MICP technique for developing sustainability in concrete
Published in European Journal of Environmental and Civil Engineering, 2023
Santosh Ashok Kadapure, Umesh B. Deshannavar, Basavaraj G. Katageri, Poonam S. Kadapure
In some cases, capsules are synthesised by using polymers or minerals (i.e., epoxy, colloidal silica, sodium silicate, ceramics, etc.). Some of the work pertaining to the use of capsules in the treatment of cracks in concrete is presented below in Table 1.