| 1. |
- Alhalaweh, Amjad, et al.
(författare)
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Surface thermodynamics of mucoadhesive dry powder formulation of zolmitriptan
- 2011
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Ingår i: AAPS PharmSciTech. - : Springer Science and Business Media LLC. - 1530-9932. ; 12:4, s. 1186-1192
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Tidskriftsartikel (refereegranskat)abstract
- Microparticle powders for nasal delivery were formulated to contain the model drug, zolmitriptan, and varying proportions of different polymers. The objective of the study was to investigate the effects of these formulative parameters on the surface chemistry of the spray-dried microparticles and their potential for adhesion to the tested substrates, porcine mucin, and nasal tissue. The polymers used were chitosans of varying ionization states and molecular weights and hydroxypropyl methyl cellulose. The surface energies of the surfaces of the microparticles were determined using contact angle measurements and the van Oss model. The theory of surface thermodynamics was applied to determine the theoretical potential for the different materials to adhere to the substrates. It was found that the drug or polymers alone, as well as the various formulations, were more likely to adhere to mucin than to nasal tissue. Further, there was a trend for higher molecular weight chitosans to adhere better to the substrates than lower molecular weight chitosans. Similarly, adhesion was improved for formulations with a higher content of polymers. These theoretical predictions may be compared with further experimental results and be of use in making informed decisions on the choice of formulations for future expensive bio-studies.
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| 2. |
- Kota, Hanumantha Rao, et al.
(författare)
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Minerals bioprocessing : R & D needs in mineral biobeneficiation
- 2010
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Ingår i: Hydrometallurgy. - : Elsevier BV. - 0304-386X .- 1879-1158. ; 104:3-4, s. 465-470
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Tidskriftsartikel (refereegranskat)abstract
- Microorganisms have a tremendous influence on their environment through the transfer of energy, charge, and materials across a complex biotic mineral-solution interface. The bio-modification of mineral surfaces involves the complex action of microorganism on the mineral surface. The manner, in which bacteria affect the surface reactivity and the mechanism of bacteria adsorption, is still unknown and accumulation of the primary data in this area is only starting. The bio-flotation and bio-flocculation processes concern the mineral response to the bacterium presence, which is essentially interplay between microorganism and the physicochemical properties of the mineral surface, such as the atomic and electronic structure, the net charge/potential, acid-base properties, and wettability of the surface. There is an urgent need for developing basic knowledge that would underpin biotechnological innovations in the natural resource (re)processing technologies that deliver competitive solutions.
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| 3. |
- Kota, Hanumantha Rao, et al.
(författare)
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Mixed anionic/non-ionic collectors in phosphate gangue flotation from magnetite fines
- 2011
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Ingår i: Open Mineral Processing Journal. - : Bentham Science Publishers Ltd.. - 1874-8414. ; 4, s. 14-24
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Tidskriftsartikel (refereegranskat)abstract
- Scientists and technologists in world over are making large efforts to streamline the conventional technological schemes of ore processing, in particular froth flotation towards reducing overall costs, limiting the use of dangerous substances, decreasing waste streams and improving waste disposal. Hitherto, search for such innovations has been performed mainly empirically and there is an urgent need to shift these technologies to be more innovative and effective.Understanding of the fundamental concepts of aquatic chemistry of minerals–selective adsorption and selective redox reactions at mineral–solution interfaces would impact innovating conventional flotation process Molecular-level knowledge and coherent understanding of minerals contacted with aqueous solutions is required which underlie great opportunities in controlling mineral–solution interfaces towards the grand challenge of tomorrow’s science and mineral processing technology. Aqueous redox chemistry of sulphides and adsorption mechanisms, the problems of metal sulphides selectivity against pyrite and fine particle flotation have been highlighted and discussed in the light of literature. The requisite knowledge and research needs to address these issues have also been briefly presented.
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| 4. |
- Kota, Hanumantha Rao, et al.
(författare)
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Revisiting sulphide mineral (bio) processing : a few priorities and directions
- 2013
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Ingår i: XV Balkan Mineral Processing Congress, 12-16 June 2013, Sozopol, Bulgaria.
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Konferensbidrag (refereegranskat)abstract
- Large efforts are being made to streamline the conventional (chemical and physical) technological schemes of ore processing, remediation and environmental protection towards reducing overall costs, limiting the use of dangerous substances, decreasing waste streams and improving waste disposal and recycling practice. Hitherto, search for such innovations has been performed mainly empirically and there is an urgent need to shift these technologies to be more innovative and effective. Alternative biotechnological solutions and solutions mimicking natural processes are also being proposed. However, except for bioleaching, practical exploitation of the biotechnological potential in extractive industries and accompanying environmental protection measures remains far from feasibility.Understanding of the fundamental concepts of aquatic chemistry of minerals–selective adsorption and selective redox reactions at mineral–bacteria–solution interfaces, impact innovating conventional and bio-flotation, as well as (bio)remediation/detoxification of mineral and chemical wastes. Molecular-level knowledge and coherent understanding of minerals contacted with aqueous solutions is required that underlie great opportunities in controlling abiotic and biotic mineral–solution interfaces towards the grand challenge of tomorrow’s science and mineral processing technology.
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| 5. |
- Kota, Hanumantha Rao, et al.
(författare)
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Revisiting Sulphide Mineral (Bio) Processing: A Few Priorities And Directions
- 2013
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Ingår i: Journal of Powder Metallurgy & Mining. - : OMICS Publishing Group. - 2168-9806. ; 2:4
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Tidskriftsartikel (refereegranskat)abstract
- Large efforts are being made to streamline the conventional (chemical and physical) technological schemes of ore processing, remediation and environmental protection towards reducing overall costs, limiting the use of dangerous substances, decreasing waste streams and improving waste disposal and recycling practice. Hitherto, search for such innovations has been performed mainly empirically and there is an urgent need to shift these technologies to be more innovative and effective. Alternative biotechnological solutions and solutions mimicking natural processes are also being proposed. However, except for bioleaching, practical exploitation of the biotechnological potential in extractive industries and accompanying environmental protection measures remains far from feasibility. Understanding of the fundamental concepts of aquatic chemistry of minerals–selective adsorption and selective redox reactions at mineral– bacteria–solution interfaces, impact innovating conventional and bio-flotation, as well as (bio) remediation/detoxification of mineral and chemical wastes are necessary. Molecular-level knowledge and coherent understanding of minerals contacted with aqueous solutions is required that underlie great opportunities in controlling abiotic and biotic mineral– solution interfaces towards the grand challenge of tomorrow’s science and mineral processing technology
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| 6. |
- Kuyumcu, Halit Z., et al.
(författare)
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Biocoagulation and its application potentials for mineral bioprocessing
- 2009
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Ingår i: Open Mineral Processing Journal. - : Bentham Science Publishers Ltd.. - 1874-8414. ; 2, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- The well-known sorting processes like density separation, separation in magnetic or electric fields and flotation, are not suitable to apply successfully within a particle-size range smaller than 10 μm. Due to insufficient selectivity of above mentioned enrichment processes the concentrate recovery at this particle size range is extremely poor, which influences accordingly the techno-economic efficiency of mineral processing negative.Based on a process design idea, investigations confirm that the biocoagulation of microorganisms and solid particles can be used to generate coarser sized coagulates which are more suitable for sorting. Experimental investigations showed that microorganisms like Saccharomyces cerevisiae and Yarrowia lipolytica and sulphide particles like galena and sphalerite below 10 μm coagulate effectively. Theoretical thermodynamic and extended DLVO theory calculations are in good agreement with microorganisms adhesion onto metal sulphides but not on silicates and selective biocoagulation of sulphides. Furthermore it has been demonstrated that flotation is suitable for the separation of the selectively formed biocoagulates.
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| 7. |
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| 8. |
- Rao, K Hanumantha, et al.
(författare)
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Flotation of phosphate gangue from magnetite fines - non-ionic surfactant as atrac collector modifier
- 2010
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Ingår i: XXV International Mineral Processing Congress. - Carlton, Vic : The Australian Institute of Mining and Metallurgy. - 9781921522284 ; , s. 1933-1943
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Konferensbidrag (refereegranskat)abstract
- Adsorption, contact angle and flotation of anionic Atrac and non-ionic ethaloxylated nonylphenol surfactant, and their mixture on apatite and magnetite were studied. The effect of calcium ions and sodium silicate on Atrac adsorption was investigated. The effect of Atrac adsorption on the contact angle data of apatite and magnetite in the presence and absence of sodium silicate was also examined. Wettability of solids depends on solids surface free energy and the surface energies of apatite and magnetite powders were calculated from polar and non-polar liquid contact angle data. A decrease in particle size increased the polar contribution to surface free energy due to unsaturated broken bonds on the surface. Atrac is seen to adsorb equally on apatite and magnetite, and the adsorption increased in the presence of calcium ions. The presence of water glass decreased the Atrac contact angle data on magnetite and also the flotation response demonstrating its role as magnetite depressant in flotation. The presence of non-ionic surfactant enhanced the Atrac flotation of apatite with no flotation of magnetite. Bench-scale flotation tests showed that 50 per cent of Atrac can be replaced with non-ionic collector without impairing the flotation results. Results also illustrate that the non-ionic adsorbs on apatite in equal amount of Atrac collector signifying 1:1 composition of anionic and non-ionic collector on apatite surface. Non-ionic head group sitting in between anionic head groups screens the electrostatic repulsion and forms compact adsorbed layer on apatite surface thereby increasing the hydrophobicity and flotation.
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| 9. |
- Rao, K. Hanumantha, et al.
(författare)
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Microorganisms in bioflotation and bioflocculation : potential application and research needs
- 2009
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Ingår i: Advanced Materials Research. - 1022-6680 .- 1662-8985. ; , s. 319-328
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Tidskriftsartikel (refereegranskat)abstract
- Conventionally, physico-chemical methods are used in mineral processing for recovering value minerals from ores. The ageing of ore processing tailings and waste rocks, and mining tailings contamination by chemical reagents constitute a major threat to the environment. It is imperative to develop novel economically more efficient and environmentally benign methods of flotation and waste processing, exploiting the intriguing and exciting ability of bacteria to selectively modify the surface properties of solids. Microorganisms have not only facilitate hydrometallurgical leaching operations but have also show a great promise in mineral beneficiation processes such as flotation and flocculation. Several laboratory investigations revealed that microorganisms could function similar to traditional reagents. Microorganisms have a tremendous influence on their environment through the transfer of energy, charge, and materials across a complex biotic mineral-solution interface. The bio-modification of mineral surfaces involves the complex action of microorganism on the mineral surface. The manner, in which bacteria affect the surface reactivity and the mechanism of bacteria adsorption, is still unknown and accumulation of the primary data in this area is only starting. The bio-flotation and bio-flocculation processes concern the mineral response to the bacterium presence, which is essentially interplay between microorganism and the physicochemical properties of the mineral surface, such as the atomic and electronic structure, the net charge/potential, acid-base properties, and wettability of the surface. There is an urgent need for developing basic knowledge that would underpin biotechnological innovations in the natural resource (re)processing technologies that deliver competitive solutions.
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| 10. |
- Rao, K. Hanumantha, et al.
(författare)
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Surface thermodynamics and extended DLVO theory of Acidithiobacillus ferroxidans cells on pyrite and chalcopyrite
- 2009
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Ingår i: Open Colloid Science Journal. - : Bentham Science Publishers Ltd.. - 1876-5300. ; 2, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- The adhesion of Acidithiobacillus ferrooxidans bacterial cells have been assessed by following the thermodynamic and extended DLVO theoretical approaches. Surface potential, interfacial tension and contact angle parameters that are necessary for the calculation of free energy of adhesion have been determined experimentally. The Hamaker constant involved in the Lifshitz-van der Waals interaction energy has been estimated by microscopic and macroscopic methods.The free energy of adhesion found to be negative on pyrite and chalcopyrite minerals indicating the adsorption of bacterial cells on these minerals. The potential energy diagrams of total interaction energy versus separation distance curves also illustrate the feasibility of bacterial cells adhesion except in a pH region where the bacterial species and minerals possess similar surface charge with high magnitude. The present theoretical analysis of bacterial adhesion on mineral surfaces found to be in good agreement with the experimental results and previous findings in the literature. Thus, the bacterial adhesion behavior on minerals can be judged and explained by considering the physico-chemical interaction forces.
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