| 1. |
- Aydin, M., et al.
(författare)
-
Synthesis, magnetic and electrical characteristics of poly(2-thiophen-3-yl-malonic acid)/Fe(3)O(4) nanocomposite
- 2012
-
Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 514, s. 45-53
-
Tidskriftsartikel (refereegranskat)abstract
- Poly(2-thiophen-3-yl-malonic acid)/Fe(3)O(4) nanocomposite was synthesized by the precipitation of Fe(3)O(4) in the presence of poly(2-thiophen-3-yl-malonic acid) (PT3MA). Characterizations of the nanocomposite were performed by XRD, FT-IR, TEM, TGA, AC/DC conductivity and dielectric measurements. The capping of PT3MA around Fe(3)O(4) nanoparticles was confirmed by FTIR spectroscopy, the interaction being between bridging oxygen of the carboxylate and the nanoparticle surface through bidentate binding. The crystallite particle sizes of 6 +/- 3 nm and 7 +/- 3 nm were obtained from XRD line profile fitting and from TEM image analysis respectively, and they are in good agreement with each other. Magnetization measurements revealed that PT3MA coated magnetite particles do not saturate at higher fields. The material showed superparamagnetic character as revealed by the absence of coercivity and remnant magnetization. Magnetic particle size was calculated as 7.3 +/- 1.0 nm from the mean magnetization term in the Langevin function which is also in conformity with the values determined from TEM micrographs and XRD line profile fitting. The TEM particle size analysis of the nanoparticles revealed the presence of a slightly modified magnetically dead nanoparticle surface. AC and DC conductivity measurements were performed to elucidate the electrical conduction characteristics of the product.
|
|
| 2. |
- Ballikaya, S., et al.
(författare)
-
Thermoelectric and thermal stability improvements in Nano-Cu 2 Se included Ag 2 Se
- 2019
-
Ingår i: Journal of Solid State Chemistry. - : Academic Press. - 0022-4596 .- 1095-726X. ; 273, s. 122-127
-
Tidskriftsartikel (refereegranskat)abstract
- Recently, silver chalcogenides have attracted great attention due to their potential application for room temperature power generation and local cooling. In this work, we report the thermoelectric properties and thermal stability of bulk Ag 2 Se with nano-Cu 2 Se inclusions ((Ag 2 Se) 1-x (Cu 2 Se) x where x = 0, 0.02 and 0.05). Ag 2 Se samples were prepared via melting, annealing and the nanocomposite was prepared by ball milling this material with required amount of nano-Cu 2 Se; finally, the samples were consolidated by spark plasma sintering. High temperature and low temperature transport properties were assessed by the measurements of the Seebeck coefficient, electrical conductivity, thermal conductivity, and Hall coefficient. The phase composition and microstructure were explored by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, while the thermal stability of samples was investigated via heating microscopy and heat capacity measurement. Room temperature PXRD and SEM indicated that two separate phases of Ag 2 Se and Cu 2 Se form in nano-Cu 2 Se included composites. Heating microscopy and the heat capacity measurement indicate that the thermal stability of Ag 2 Se is enhanced with increasing nano-Cu 2 Se inclusions. The sign of the Seebeck coefficient, in agreement with the Hall coefficient, shows that electrons are the dominant carriers in all samples. The electrical conductivity of the samples increases and the Seebeck coefficient decreases with increasing amount of the nano-Cu 2 Se inclusion, likely due to augmented carrier concentration. Despite the larger electrical conductivity, the thermal conductivity is suppressed with nano-Cu 2 Se inclusions. A high power factor and reduced thermal conductivity lead to a maximum ZT value of 0.45 at 875 K for (Ag 2 Se) 1-x (nano-Cu 2 Se) x sample where x is 0.05.
|
|
| 3. |
- Bhattacharya, K., et al.
(författare)
-
Lactoperoxidase-mediated degradation of single-walled carbon nanotubes in the presence of pulmonary surfactant
- 2015
-
Ingår i: Carbon. - : Elsevier BV. - 0008-6223 .- 1873-3891. ; 91, s. 506-517
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon nanotubes (CNTs) may elicit inflammatory responses following pulmonary exposure. Conversely, enzymatic biodegradation of CNTs by inflammatory cells has also been reported. The aim of this study was to study the degradation of oxidized single-walled CNTs (ox-SWCNTs) by lactoperoxidase (LPO), a secreted peroxidase present in the airways, and whether pulmonary surfactant affects this biodegradation. To this end, ox-SWCNTs were incubated in vitro with recombinant bovine LPO + H2O2 + NaSCN in the presence and absence of porcine lung surfactant (Curosurf®) and biodegradation was monitored using UV-Vis-NIR spectroscopy, Raman spectroscopy, and scanning electron microscopy. The interaction of recombinant LPO with bundles of ox-SWCNTs was confirmed by atomic force microscopy. Cell-free biodegradation of ox-SWCNTs was also observed ex vivo in murine bronchoalveolar lavage fluid in the presence of H2O2 + NaSCN. Our study provides evidence for biodegradation of ox-SWCNTs with a lung surfactant 'bio-corona' and expands the repertoire of mammalian peroxidases capable of biodegradation of ox-SWCNTs. These findings are relevant to inhalation exposure to these materials, as LPO serves as an important component of the airway defense system.
|
|
| 4. |
- Doddapaneni, Venkatesh, et al.
(författare)
-
Engineered PMMA-ZnO nanocomposites for improving the electric arc interruption capability in electrical switching applications : Unprecedented experimental insights
- 2017
-
Ingår i: Composites Science And Technology. - : Elsevier. - 0266-3538 .- 1879-1050. ; 141, s. 113-119
-
Tidskriftsartikel (refereegranskat)abstract
- Polymer inorganic nanocomposites (PINCs) have been engineered for controlling the electrical arc and to improve the arc interruption capability of the electrical switching applications, like circuit breakers. Several PINCs are fabricated by formation of ZnO quantum dots (QDs) in a poly (methyl methacrylate) (PMMA) matrix via in-situ polymerization method to avoid agglomeration of QDs, leading to a good spatial distribution of QDs in the polymer matrix. These PINCs have been characterized in detail for the morphology of QDs, interaction between QDs and polymer matrix, and ultraviolet (UV) radiation absorption. ZnO QDs have been assessed to have particle diameter of 3.5 nm, and their presence in the PMMA is revealed by the unique luminescence characteristics of the QDs under UV light. The presence of ZnO QDs broadened the range of UV radiation absorption of PMMA and the absorption edge is gradually shifted from 270 nm to 338 nm with step-wise loading of ZnO QDs. The PINCs are tested to determine their reproducibility and impact on the electrical arcs of current 1.6 kA generated using a specially designed test-setup. Interaction of PINCs with the electrical arcs generates ablation of chemical species towards core of the electrical arc, resulting in increase of voltage leading to cool-down the arc temperature. This experimental study demonstrates for the first time that these PINCs are reproducible, reliable and provides superior arc interruption capability.
|
|
| 5. |
- Doddapaneni, Venkatesh, et al.
(författare)
-
New experimental insights for controlling the electrical arcs in electrical switching applications : a comparative study on PMMA nanocomposites of Au and ZnO
- 2017
-
Ingår i: Composites Science And Technology. - : Elsevier. - 0266-3538 .- 1879-1050.
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Polymer inorganic nanocomposites (PINCs) are developed, not only due to scientific interest but also improving theelectric arc interruption process in the electrical switching applications like circuit breakers. The novelty of this work isin integrating the current developments in PINCs into electrical switching application in order to extend the limits of thepower switching devices. Several PINCs are fabricated by using pre-synthesized Au nanoparticles (NPs) of size 2.75 ±0.4 nm and poly (methyl methacrylate) (PMMA) matrix via in-situ polymerization method. Six homogeneous PINCsamples with ultra-low wt% of Au NPs varying from 0.0003 to 0.005 wt% have been fabricated. We find that thepresence of Au NPs improved the convective heat transfer and visible optical radiation absorption of PMMA. Thefabricated PINCs are tested for their arc interruption performance and the results are compared with ZnO PINCs in ourearlier work. The results of the experiments insights demonstrate the impact of PINCs on the electrical arcs and theirpotential advantages of having PINCs for the electric arc interruption process in high power switching devices.
|
|
| 6. |
- Doddapaneni, Venkatesh
(författare)
-
On the polymer-based nanocomposites for electrical switching applications
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recent research demonstrated that polymer based nanocomposites (PNCs) have been engineered in order to improve the arc interruption capability of the circuit breakers. PNCs are the combination of nano-sized inorganic nanoparticles (NPs) and polymers, opened up new developments in materials science and engineering applications. Inorganic NPs are selected based on their physical and chemical properties which could make multifunctional PNCs in order to interrupt the electrical arcs effectively. In particular, we presented the PNCs fabricated by using CuO, Fe3O4, ZnO and Au NPs in a poly (methyl methacrylate) (PMMA) matrix via in-situ polymerization method, recently developed method to avoid NPs agglomeration, leading to good spatial distribution in the polymer matrix. Thus, several samples with various wt% of NPs in PMMA matrix have been fabricated. These PNCs have been characterized in detail for the morphology of NPs, interaction between NPs and polymer matrix, and radiative/thermal energy absorption properties. In the next stage, PNCs are tested to determine their arc interruption performance and impact on the electrical arcs of current 1.6 kA generated using a specially designed test set-up. When PNCs interact with the electrical arcs, they generate ablation of chemical species towards core of the electrical arc, resulting in cooling-down the arc due to strong temperature and pressure gradient in the arc quenching domain. This thesis demonstrates for the first time that these engineered PNCs are easily processed, reproducible, and can be used to improve the arc interruption process in electrical switching applications.
|
|
| 7. |
- Khalil, Alaa, et al.
(författare)
-
Surface modified of polyacrylonitrile nanofibers by TiO2/MWCNT for photodegradation of organic dyes and pharmaceutical drugs under visible light irradiation
- 2019
-
Ingår i: Environmental Research. - : Academic Press. - 0013-9351 .- 1096-0953. ; 179
-
Tidskriftsartikel (refereegranskat)abstract
- This work describes the fabrication of two composite nanofibers systems containing polyacrylonitrile polymer (PAN), Multiwall carbon nanotubes (MWCNT) and Titania (TiO2) nanoparticles. Photodegradation experiments were performed to study the effect of various parameters including pH, catalyst dose, pollutant concentration and reaction time for three model compounds, methylene blue (MB), indigo carmine (IC), and ibuprofen (IBU) under visible light. Morphology and structure of the modified composite nanofibers were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Thermogravimetric analysis (TGA), Photoluminescence (PL) spectroscopy, Raman spectra, and X-ray Photoelectron Spectra (XPS) analyses. The photocatalytic performance was achieved in a rather short time visible light (<30 min) and under low power intensity (125 W) compared to earlier reports. Kinetics data fitted well using pseudo-first order model to describe the mechanism of photocatalytic degradation processes. The stability and flexibility of the fabricated composite nanofibers allow their application in a continuous flow system and their re-use after several cycles.
|
|
| 8. |
- Lobov, Gleb S., et al.
(författare)
-
Electro-optical response of P3HT nanofibers in liquid solution
- 2015
-
Ingår i: Asia Communications and Photonics Conference 2015. - : Optical Society of America. - 9781943580064
-
Konferensbidrag (refereegranskat)abstract
- AC electric poling introduces in P3HT nanofibers anisotropic electro-optical response and birefringence. Along with birefringence, such material exhibits strong amplitude modulation which makes it more efficient alternative to liquid crystals.
|
|
| 9. |
- Mohamed, Alaa, et al.
(författare)
-
Surface functionalized composite nanofibers for efficient removal of arsenic from aqueous solutions
- 2017
-
Ingår i: Chemosphere. - : Elsevier Ltd. - 0045-6535 .- 1879-1298. ; 180, s. 108-116
-
Tidskriftsartikel (refereegranskat)abstract
- A novel composites nanofiber was synthesized based on PAN-CNT/TiO2-NH2 nanofibers using electrospinning technique followed by chemical modification of TiO2 NPs. PAN-CNT/TiO2-NH2 nanofiber were characterized by XRD, FTIR, SEM, and TEM. The effects of various experimental parameters such as initial concentration, contact time, and solution pH on As removal were investigated. The maximum adsorption capacity at pH 2 for As(III) and As(V) is 251 mg/g and 249 mg/g, respectively, which is much higher than most of the reported adsorbents. The adsorption equilibrium reached within 20 and 60 min as the initial solution concentration increased from 10 to 100 mg/L, and the data fitted well using the linear and nonlinear pseudo first and second order model. Isotherm data fitted well to the linear and nonlinear Langmuir, Freundlich, and Redlich-Peterson isotherm adsorption model. Desorption results showed that the adsorption capacity can remain up to 70% after 5 times usage. This work provides a simple and an efficient method for removing arsenic from aqueous solution.
|
|
| 10. |
- Mukherjee, Sourav P., et al.
(författare)
-
Graphene oxide is degraded by neutrophils and the degradation products are non-genotoxic
- 2018
-
Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 10:3, s. 1180-1188
-
Tidskriftsartikel (refereegranskat)abstract
- Neutrophils were previously shown to digest oxidized carbon nanotubes through a myeloperoxidase (MPO)-dependent mechanism, and graphene oxide (GO) was found to undergo degradation when incubated with purified MPO, but there are no studies to date showing degradation of GO by neutrophils. Here we produced endotoxin-free GO by a modified Hummers' method and asked whether primary human neutrophils stimulated to produce neutrophil extracellular traps or activated to undergo degranulation are capable of digesting GO. Biodegradation was assessed using a range of techniques including Raman spectroscopy, transmission electron microscopy, atomic force microscopy, and mass spectrometry. GO sheets of differing lateral dimensions were effectively degraded by neutrophils. As the degradation products could have toxicological implications, we also evaluated the impact of degraded GO on the bronchial epithelial cell line BEAS-2B. MPO-degraded GO was found to be non-cytotoxic and did not elicit any DNA damage. Taken together, these studies have shown that neutrophils can digest GO and that the biodegraded GO is non-toxic for human lung cells.
|
|
| 11. |
- Nikkam, N., et al.
(författare)
-
Fabrication and thermo-physical characterization of silver nanofluids : An experimental investigation on the effect of base liquid
- 2018
-
Ingår i: International Communications in Heat and Mass Transfer. - : Elsevier. - 0735-1933 .- 1879-0178. ; 91, s. 196-200
-
Tidskriftsartikel (refereegranskat)abstract
- Nanofluids (NFs) are solid-liquid composites prepared by stabilizing nanoparticles (NPs) in a base liquid, which is selected based on the technological area of application. For heat exchange applications the base liquid can be specified as water, ethylene glycol (EG), or their mixture. NFs have exhibited some potential to replace conventional heat transfer fluids due to enhancement of their thermal characteristics. The thermo-physical properties of NFs including thermal conductivity (TC) and viscosity may be affected by several factors including the base liquid, which is not well studied in the literature. Focus of the present work is to study the impact of base liquid by comparing the TC and viscosity of a commercial silver (Ag) NFs with lab-made water, EG and water/ethylene glycol (W/EG) mixture (50:50 by wt%) at different Ag NP loadings (1, 1.5 and 2 wt%). For this purpose, commercial water based Ag suspension (containing 1 wt% Ag NP) was acquired, which is used for the preparation of Ag NFs with different base liquids and NP loadings. Finally, the thermo-physical properties of NFs including TC and viscosity were measured and analyzed at 20 °C. The results revealed that W/EG based NFs containing 2 wt% Ag NP showed best performance with the highest TC enhancement of 12.4% and only 6.1% increase in viscosity, revealing that among different base liquids, W/EG based NFs are the most beneficial for heat transfer applications.
|
|
