| 1. |
- Baruah, Sunandan, et al.
(författare)
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Development of a visible light active photocatalytic portable water purification unit using ZnO nanorods
- 2012
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Ingår i: Catalysis Science & Technology. - 2044-4753 .- 2044-4761. ; 2:5, s. 918-921
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Tidskriftsartikel (refereegranskat)abstract
- A ZnO nanorods based water purification unit was designed which operates with solar energy as the source of activation. The purifier was tested on two model bacteria Escherichia coli and Staphylococcus aureus with concentration as high as 1010 colony forming units (CFU) per litre, which is about 105 times higher than the bacterial concentration in tap water. Up to 99% (0.99 × 1010 CFU L−1) removal of viable bacterial cells was achieved under sunlight activation.
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| 2. |
- Baruah, Sunandan, et al.
(författare)
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Development of a visible light active photocatalytic portable water purification unit using ZnO nanorods
- 2012
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Ingår i: Catalysis Science & Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 2:5, s. 918-921
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Tidskriftsartikel (refereegranskat)abstract
- A ZnO nanorods based water purification unit was designed which operates with solar energy as the source of activation. The purifier was tested on two model bacteria Escherichia coli and Staphylococcus aureus with concentration as high as 10(10) colony forming units (CFU) per litre, which is about 10(5) times higher than the bacterial concentration in tap water. Up to 99% (0.99 x 10(10) CFU L-1) removal of viable bacterial cells was achieved under sunlight activation.
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| 3. |
- Baruah, Sunandan, et al.
(författare)
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Enhanced visible light photocatalysis through fast crystallization of zinc oxide nanorods
- 2010
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Ingår i: Beilstein Journal of Nanotechnology. - : Beilstein-Institut. - 2190-4286. ; 1:1, s. 14-20
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Tidskriftsartikel (refereegranskat)abstract
- Hydrothermally grown ZnO nanorods have inherent crystalline defects primarily due to oxygen vacancies that enhance optical absorption in the visible spectrum, opening up possibilities for visible light photocatalysis. Comparison of photocatalytic activity of ZnO nanorods and nanoparticle films on a test contaminant methylene blue with visible light irradiation at 72 kilolux (klx) showed that ZnO nanorods are 12–24% more active than ZnO nanoparticulate films. This can be directly attributed to the increased effective surface area for adsorption of target contaminant molecules. Defects, in the form of interstitials and vacancies, were intentionally created by faster growth of the nanorods by microwave activation. Visible light photocatalytic activity was observed to improve by ≈8% attributed to the availability of more electron deficient sites on the nanorod surfaces. Engineered defect creation in nanostructured photocatalysts could be an attractive solution for visible light photocatalysis.
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| 4. |
- Baruah, Sunandan, et al.
(författare)
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Manganese doped zinc sulfide quantum dots for detection of Escherichia coli
- 2012
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Ingår i: Journal of Fluorescence. - : Springer Science+Business Media B.V.. - 1053-0509 .- 1573-4994. ; 22:1, s. 403-408
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Tidskriftsartikel (refereegranskat)abstract
- A novel biocompatible chitosan passivated manganese doped zinc sulfide (Mn doped ZnS) nanophosphor has been synthesized through a simple aqueous precipitation reaction. Upon excitation with ultraviolet light, the quantum dots (QDs) emit an orange luminescence peaking at 590 nm, which is visible to the naked eye. These chitosan coated Mn doped ZnS QDs can have potential applications in bio-labeling, particularly in fluorescence-based imaging. One of the envisioned applications of these QDs is in improving the conventional, organic dye-reliant Fluorescence in situ Hybridization (FISH) technique, a widely used method for microbial detection. Here we demonstrate that the chitosan-capped Mn doped ZnS QDs are suitable for this purpose.
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| 5. |
- Baruah, Sunandan, et al.
(författare)
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Nanotechnology in Water Treatment
- 2015
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Ingår i: Pollutants in Buildings, Water and Living Organisms. - Cham : Springer International Publishing. - 9783319192765 ; , s. 51-84
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Industrialization and excessive use of pesticides for boosting agricultural production has adversely affected the ecosystem, thus polluting natural water reserves. Remediation of contaminated water has been an area of concern with numerous techniques being applied to improve the quality of naturally available water to the level suitable for human consumption. Most of these methods however generate byproducts that are sometimes toxic. Heterogenous photocatalysis using metal oxide nanostructures for water purification is an attractive option because no harmful byproducts are created. A discussion on possible methods to engineer metal oxides for visible light photocatalysis is included to highlight the use of solar energy for water purification. Multifunctional photocatalytic membranes are considered advantageous over freely suspended nanoparticles due to the ease of its removal from the purified water. An overview of water remediation techniques is presented highlighting innovations through nanotechnology for possible addressing of problems associated with current techniques.
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| 6. |
- Baruah, Sunandan, et al.
(författare)
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Perspectives and applications of nanotechnology in water treatment
- 2016
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Ingår i: Environmental Chemistry Letters. - : Springer. - 1610-3653 .- 1610-3661. ; 14:1, s. 1-14
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Forskningsöversikt (refereegranskat)abstract
- Industrialization and excessive use of pesticides for boosting agricultural production have adversely affected the ecosystem, polluting natural water reserves. Remediation of contaminated water has been an area of concern with numerous techniques being applied to improve the quality of naturally available water to the level suitable for human consumption. Most of these methods, however, generate by-products that are sometimes toxic. Heterogenous photocatalysis using metal oxide nanostructures for water purification is an attractive option because no harmful by-products are created. A discussion on possible methods to engineer metal oxides for visible light photocatalysis is included to highlight the use of solar energy for water purification. Multifunctional photocatalytic membranes are considered advantageous over freely suspended nanoparticles due to the ease of its removal from the purified water. An overview of water remediation techniques is presented, highlighting innovations through nanotechnology for possible addressing of problems associated with current techniques.
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| 7. |
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| 8. |
- Boonyanitipong, Prapatsorn, et al.
(författare)
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Toxicity of ZnO and TiO2 Nanoparticles on Germinating Rice Seed
- 2011
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Ingår i: International Journal of Bioscience, Biochemistry and Bioinformatics. - : International Association of Computer Science & Information Technology Press. - 2010-3638. ; 1, s. 282-285
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Tidskriftsartikel (refereegranskat)abstract
- The present study is aimed at investigating the effects of zinc oxide nanoparticles (nano-ZnO) and titanium dioxide nanoparticles (nano-TiO2) on rice (Oryza sativa L.) roots. Three parameters are examined in this study: seed germination percentage, root length, and number of roots. The results show that there is no reduction in the percent seed germination from both nanoparticles, however nano-ZnO is observed to have detrimental effects on rice roots at early seedling stage. Nano-ZnO is found to stunt roots length and reduce number of roots. Whereas nano-TiO2 has no effect on root length. This study shows that direct exposure to specific types of nanoparticles causes significant phytotoxicity, emphasizes the need for ecologically responsible disposal of wastes containing nanoparticles and also highlights the necessity for further study on the impacts of nanoparticles on agricultural and environmental systems.
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| 9. |
- Borah, Sandhya Banti Dutta, et al.
(författare)
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Heavy Metal Ion Sensing By Surface Plasmon Resonance on Gold Nanoparticles
- 2014
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Ingår i: ADBU Journal of Engineering Technology. - : Don Bosco University. - 2348-7305. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- Surface Plasmon resonance (SPR) based heavy metal ions sensor is one of the most sensitive sensor for detecting toxic metal ions. It is an inexpensive, portable and also feasible for real time detection. SPR sensor is a type of optical sensor in which toxic metal ions get adsorbed on the functionalized metal (mostly Au) film causes the change in refractive index of the metal (Au)-dielectric (sensing) medium. The change of the refractive index leads to a shift in the angular spectrum of the reflected light and can be accurately monitored by optical methods. In this paper,we are trying to optimize the detection level of heavy metal ions by surface plasmon resonance on gold nanoparticles using UV-VIS spectroscopy. Polymer like chitosan is being used with gold nanoparticles to detect copper and zinc ions and detection till very low concentrations of the toxic metal ions is obtained.
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| 10. |
- Borah, Sandhya B.D., et al.
(författare)
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Heavy metal ion sensing in water using surface plasmon resonance of metallic nanostructures
- 2015
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Ingår i: Groundwater for Sustainable Development. - : Elsevier. - 2352-801X. ; 1:1-2, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Heavy metal contamination in water and other ecosystems is one of the major environmental issues and already gaining significant attention across the world. For monitoring heavy metals in the environmental ecosystem, optical sensors are getting popular due to their high sensitivity and ease of use. Application of nanomaterials in the sensor elements further improves the sensitivity due to their large surface-to-volume ration, high reactivity, high degree of functionalization and size-dependent properties. This article mainly reviews the application of various metallic nanostructures for heavy metal ion sensing based on surface plasmon resonance (SPR). SPR sensors are widely applied in real time monitoring of heavy metals, chemical and biological analytes etc., because of their ability to efficiently detect and quantify these contaminants even at much diluted conditions (ng/L levels). In this article, SPR sensors fabricated with several metallic nanostructures, such as gold and silver, and their shape and size effects on sensor performance for heavy metal ion detection is discussed. Techniques used to improve the performance of such SPR sensors are also reviewed briefly.
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| 11. |
- Jaisai, Mayuree, et al.
(författare)
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Paper modified with ZnO nanorods–antimicrobial studies
- 2012
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Ingår i: Beilstein Journal of Nanotechnology. - : BEILSTEIN-INSTITUT. - 2190-4286. ; 3:1, s. 684-691
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Tidskriftsartikel (refereegranskat)abstract
- Paper with antimicrobial properties was developed through in situ growth of ZnO nanorods. The targeted application for this type of paper is in health centers as wallpaper, writing paper, facemasks, tissue paper, etc. The paper was tested on three model microbes, Gram-positive bacteria Staphylococcus aureus, Gram-negative bacteria Escherichia coli and common airborne fungus Aspergillus niger. No viable bacterial colonies or fungal spores could be detected in the areas surrounding test samples of the antimicrobial paper. Gram-negative bacteria Escherichia coli were found to be inhibited in an area that is 239% and 163% the area of the paper sample under different room lighting conditions, i.e., halogen and fluorescent lamp illumination, respectively. For Gram-positive bacteria Staphylococcus aureus the zones of inhibition surrounding the paper samples are 102% and 70%, and for Aspergillus niger, 224% and 183% of the sample area, under similar lighting conditions.
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| 12. |
- Mahmood, Mohammad Abbas, et al.
(författare)
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Heterogeneous photocatalysis for removal of microbes from water
- 2012
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Ingår i: Environmental Chemistry Letters. - : Springer Berlin/Heidelberg. - 1610-3653 .- 1610-3661. ; 10:2, s. 145-151
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Tidskriftsartikel (refereegranskat)abstract
- Increasing water pollution by microbes has become a source of serious health concern across the globe. Production of potentially carcinogenic disinfection by-products has marred credibility of traditional water purification techniques like chlorination. Photocatalysis has emerged as a promising alternative technique for the disinfection of water with minimal risk of harmful by-products. The process involves a wide band gap semiconductor material which, upon irradiation of light, produces electrons and holes with high redox potential to degrade organic contaminants and microbes. In this review, we analyze the research trends in photocatalytic inactivation of water borne microorganisms. This report analyzes the major factors that affect the disinfection efficiency using this process. The discussion also includes plausible mechanisms of microbial degradation as well as a kinetic model of the inactivation process. Different approaches, like doping of semiconductors or energy band engineering or plasmon coupling, have been reported for the enhancement and utilization of ambient solar light. Photocatalysis could be a cost-effective and environmentally friendly water purification technique though further research is required to enhance its efficiency with the use of solar light.
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| 13. |
- Makhal, Abhinandan, et al.
(författare)
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Dynamics of light harvesting in ZnO nanoparticles
- 2010
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Ingår i: Nanotechnology. - : Institute of Physics (IOP). - 0957-4484 .- 1361-6528. ; 21:26, s. 265703-1
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Tidskriftsartikel (refereegranskat)abstract
- We have explored light harvesting of the complex of ZnO nanoparticles with the biological probe Oxazine 1 in the near-infrared region using picosecond-time-resolved fluorescence decay studies. We have used ZnO nanoparticles and Oxazine 1 as a model donor and acceptor, respectively, to explore the efficacy of the Förster resonance energy transfer (FRET) in the nanoparticle–dye system. It has been shown that FRET from the states localized near the surface and those in the bulk of the ZnO nanoparticles can be resolved by measuring the resonance efficiency for various wavelengths of the emission spectrum. It has been observed that the states located near the surface for the nanoparticles (contributing to visible emission at λ≈550 nm) can contribute to very high efficiency (>90%) FRET. The efficiency of light harvesting dynamics of the ZnO nanorods has also been explored in this study and they were found to have much less efficiency (~40%) for energy transfer compared to the nanoparticles. The possibility of an electron transfer reaction has been ruled out from the picosecond-resolved fluorescence decay of the acceptor dye at the ZnO surface.
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| 14. |
- Promnimit, S., et al.
(författare)
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Hydrothermal growth of ZnO hexagonal nanocrystals : Effect of growth conditions
- 2013
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Ingår i: Journal of Nano Research. - : Trans Tech Publications Inc.. - 1662-5250 .- 1388-0764 .- 1572-896X. ; 21, s. 57-63
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Tidskriftsartikel (refereegranskat)abstract
- Hexagonal ZnO nanocrystals were synthesized through a hydrothermal route under mild conditions (growth temperature of 90°C at atmospheric pressure). Pre-synthesized ZnO nanoparticles were used to serve as nucleation sites for the growth of the nanocrystals. The growth of ZnO nanorods was found to be surface independent. The dimensions of the hexagonal ZnO nanocrystals were observed to be dependent on the concentration of the reactants used (sources of Zn2+ and OH- ions), pH of the growth bath and also on the duration of crystal growth. The average diameter and height of the ZnO nanocrystals was found to be directly proportional to the concentration of the reactants as well as hydrolysis time. The orientation of the nanocrystals was found to be dependent upon the seeding method employed. Hexagonal single crystals of a wide range of dimensions and aspect ratios could be successfully synthesized through a control of growth parameters.
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| 15. |
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| 16. |
- Sarkar, Soumik, et al.
(författare)
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Nanoparticle-Sensitized Photodegradation of Bilirubin and Potential Therapeutic Application
- 2012
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:17, s. 9608-9615
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Tidskriftsartikel (refereegranskat)abstract
- Bilirubin (BR) is a protective antioxidant; however, when its conjugation and excretion are impaired, as in neonatal and hereditary jaundice, BR accumulates and may cause severe neurotoxicity. Here, we report a novel mechanism for ZnO nanoparticle (NP)-sensitized BR degradation via defect-mediated nonradiative energy transfer pathway. Among different sizes and shapes, ZnO particles with diameter of 5 nm having very high concentration of defect states are found to be the most effective catalyst, which particularly follows a pseudofirst-order kinetics validating the Langmuir–Hinshelwood model of surface catalysis. The nontoxic wide band gap ZnO NPs essentially transmit defect-mediated visible optical radiation, which is not supposed to interfere with the conventional phototherapy process. Therefore, the recyclable ZnO nanocatalysts essentially invite an added advantage in potential therapeutic applications and/or in a flow-device that has been explored in the present study.
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| 17. |
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