Reduction of silver nanoparticle toxicity affecting ammonia oxidation using cell entrapment technique

2019 ◽  
Vol 79 (5) ◽  
pp. 1007-1016 ◽  
Author(s):  
Nguyen Thanh Giao ◽  
Tawan Limpiyakorn ◽  
Pumis Thuptimdang ◽  
Thunyalux Ratpukdi ◽  
Sumana Siripattanakul-Ratpukdi
Keyword(s):  
Polyvinyl Alcohol ◽  
Ammonia Oxidation ◽  
Cell Damage ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
X Ray ◽  
Cell Entrapment ◽  
Inhibition Kinetic ◽  
Scanning Electron Microscopic ◽  
Silver Toxicity

Abstract Occurrence of silver nanoparticles (AgNPs) in wastewater treatment systems could impact the ammonia oxidation (AO). This study investigated the reduction of AgNPs and dissociated silver ion (Ag+) toxicity on nitrifying sludge using cell entrapment technique. Three entrapment materials, including barium alginate (BA), polyvinyl alcohol (PVA), and a mixture of polyvinyl alcohol and barium alginate (PVA-BA), were applied. The BA beads provided the highest reduction of silver toxicity (up to 90%) and durability. Live/dead assays showed fatality of entrapped cells after exposure to AgNPs and Ag+. The maximum AO rate of the BA-entrapped cells was 5.6 mg-N/g-MLSS/h. The AO kinetics under the presence of silver followed an uncompetitive inhibition kinetic model. The experiments with AgNPs and Ag+ gave the apparent maximum AO rates of 4.2 and 4.8 mg-N/g-MLSS/h, respectively. The apparent half-saturation constants of the BA-entrapped cells under the presence of silver were 10.5 to 13.4 mg/L. Scanning electron microscopic observation coupled with energy-dispersive X-ray spectroscopy indicated no silver inside the beads. This elucidates that the silver toxicity can be reduced by preventing silver penetration through the porous material, leading to less microbial cell damage. This study revealed the potential of the entrapment technology for mitigating the effect of silver species on nitrification.

Epitaxial Growth of α-Fe2O3 Thin Films on c-Plane Sapphire Substrate by Hydrothermal Method

2011 ◽  
Vol 702-703 ◽  
pp. 999-1002 ◽  
Author(s):  
Song Li ◽  
Gao Wu Qin ◽  
Liang Zuo
Keyword(s):  
Thin Films ◽  
Gas Sensors ◽  
Sapphire Substrate ◽  
Electron Microscopic Observation ◽  
Interface Energy ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Scanning Electron Microscopic ◽  
Hydrolysis Of

Thin films of hematite find extensive applications in photoelectrochemistry, photocatalysis, and gas sensors. c-axis oriented hematite films have been directly grown on c-plane sapphire substrate using chemical method via hydrolysis of ferric cations. X-ray diffraction (XRD) reveals that the crystalline phases of the films and corresponding sediment produced in the solution were α-Fe2O3 and pure β-FeOOH, demonstrating the promotion of nucleation of hematite on sapphire substrate as a result of lowered interface energy. Phi-scan results indicate that the hematite films are grown with (0001) planes parallel to c-plane of Al2O3. Scanning electron microscopic observation shows that the hematite films are composed of pyramid-shaped nanocrystals with smooth surface facets.

scholarly journals Three-Dimensional Analyses of Morphology of Polymer Spherulites by X-ray Computerized Tomography

2014 ◽  
Vol 70 (a1) ◽  
pp. C1778-C1778
Author(s):  
Tien Nguyen-Dung ◽  
Yukihiro Nishikawa ◽  
Masato Hashimoto ◽  
Masatoshi Tosaka ◽  
Sono Sasaki ◽  
...  
Keyword(s):  
Structural Model ◽  
Three Dimensional ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
X Ray ◽  
3 Dimensional ◽  
Scanning Electron Microscopic ◽  
Radial Cracks ◽  
First Time ◽  
Good Agreement

We report 3-dimensional structural analyses of huge spherulites of poly(oxyethylene) (PEG) by the X-ray computerized tomographic (CT) observation in blends of PEG and amorphous poly(lactide). The formation of the huge spherulites is characteristic of PEG and its direct observation by the X-ray CT is reported here for the first time. Slit-shaped cracks were clearly observed by the X-ray CT. Not only the straight cracks but also curved ones were found and it seemed that they overall formed a set of spokes. Furthermore, the scanning electron microscopic observation revealed that the cracks were parallel to bundles of lamellar crystallites. From those observations, we conclude that a set of radial cracks observed under the X-ray CT is a signature of a huge spherulite. Several aspects of an axialite structure are presented and a good agreement with the intuitively proposed structural model is obtained.

The Scanning Electron Microscopic Observation of the Vestibular Sensory Epithelia

1969 ◽  
Vol 27 ◽  
pp. 40-41
Author(s):  
D.J. Lim ◽  
W.C. Lane
Keyword(s):  
Semicircular Canals ◽  
Electron Microscopic Observation ◽  
Gravitational Acceleration ◽  
Electron Microscopic ◽  
Sensory Epithelia ◽  
Scanning Electron Microscopic ◽  
Vestibular Sensory Epithelia ◽  
And Function ◽  
Sand Piles ◽  
Active Investigation

The morphology and function of the vestibular sensory organs has been extensively studied during the last decade with the advent of electron microscopy and electrophysiology. The opening of the space age also accelerated active investigation in this area, since this organ is responsible for the sensation of balance and of linear, angular and gravitational acceleration.The vestibular sense organs are formed by the saccule, utricle and three ampullae of the semicircular canals. The maculae (sacculi and utriculi) have otolithic membranes on the top of the sensory epithelia. The otolithic membrane is formed by a layer of thick gelatin and sand-piles of calcium carbonate crystals (Fig.l).

scholarly journals HCl Gas Sensor Coating Based on Poly(N-isopropylacrylamide) Nanoparticles Prepared from Water-Methanol Binary Solvent

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3283 ◽  
Author(s):  
Masanobu Matsuguchi ◽  
Shinnosuke Fujii
Keyword(s):  
Room Temperature ◽  
Pure Water ◽  
Electron Microscopic Observation ◽  
Spherical Particles ◽  
Binary Solvent ◽  
Electron Microscopic ◽  
Coated Nanoparticles ◽  
Water Solvent ◽  
Scanning Electron Microscopic ◽  
Hcl Gas

Poly(N-isopropylacrylamide) (PNIPAM) nanoparticles formed in water-methanol binary solvent were successfully deposited on a resonator surface at room temperature by exploiting the cononsolvency effect on the phase transition of PNIPAM aqueous solutions. Scanning electron microscopic observation revealed that the nanoparticles were secondary and made up of agglomerated primary spherical particles of about 10-nm diameter, buried in the film. The magnitude of the sensor response toward HCl gas was larger than that of the nanoparticle sensor prepared from pure water solvent, and the sensitivity to 1 ppm of HCl of sensor-coated nanoparticles based on the present method was 3.3 Hz/ppm. The recovery of the sensors was less than 90% at first cycle measurement, but had improved to almost 100% at the third cycle.

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