| 1. |
- Imran, Z, et al.
(författare)
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Fabrication of cadmium titanate nanofibers via electrospinning technique
- 2012
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 38:4, s. 3361-3365
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Tidskriftsartikel (refereegranskat)abstract
- Here we present an electrospinning technique for the fabrication of cadmium titanate/polyvinyl-pyrrolidone composite nanofibers. The composite nanofibers are then annealed at 600 degrees C to obtain ilmenite rhombohedral phase cadmium titanate nanofibers. The structure, composition, thermal stability and optical properties of as synthesized and annealed cadmium titanate nanofibers are characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy. The average diameter and length of the nanofibers are found to be similar to 150-200 nm and similar to 100 mu m, respectively.
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| 2. |
- Batool, S S., et al.
(författare)
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Comparative Analysis of Ti, Ni, and Au Electrodes on Characteristics of TiO2 Nanofibers for Humidity Sensor Application
- 2013
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Ingår i: Journal of Materials Science & Technology. - : Elsevier. - 1005-0302. ; 29:5, s. 411-414
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Tidskriftsartikel (refereegranskat)abstract
- The effect of metal (Ti, Ni, and Au) electrodes on humidity sensing properties of electrospun TiO2 nanofibers was investigated in this work. The devices were fabricated by evaporating metal contacts on SiO2 layer thermally grown on silicon substrate. The separation between the electrodes was 90 mm for all sensors. The sensors were tested from 40% to 90% relative humidity (RH) by AC electrical characterization at room temperature. When sensors are switched between 40% and 90% RH, the corresponding response and recovery time are 3 s and 5 s for Ti-electrode sensor, 4 s and 7 s for Ni-electrode sensor, and 7 s and 13 s for Au-electrode sensor. The hysteresis was 3%, 5% and 15% for Ti-, Ni-, and Au-electrode sensor, respectively. The sensitivity of Ti, Ni, and Au-electrode sensors are 7.53 M Omega/% RH, 5.29 MU/% RH and 4.01 M Omega/% RH respectively at 100 Hz. Therefore Ti-electrode sensor is found to have linear response, fast response and recovery time and higher sensitivity as compared with those of Ni- and Au-electrode sensors. Comparison of humidity sensing properties of sensors with different electrode material may propose a compelling route for designing and optimizing humidity sensors.
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| 3. |
- Batool, S S, et al.
(författare)
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Silica nanofibers based impedance type humidity detector prepared on glass substrate
- 2013
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Ingår i: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 87, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Impedance type relative humidity detector is fabricated by depositing electrospun silica nanofibers on glass substrate. The silica nanofibers with an average diameter similar to 150 nm and length similar to 100 mu m were used. Thermogravimetric and differential scanning calorimetric analysis confirm that the accurate annealing temperature is 500 degrees C for complete removal of PVP. Humidity detecting devices were fabricated by defining titanium electrodes on top of the silica nanofibers. The performance of silica nanofibers humidity detectors was tested by AC electrical measurements at 40-90% relative humidity. The response and the recovery times were 5 s and 3 s, respectively, between 40% and 90% relative humidity. Contribution of dipoles, space charge polarization, relaxation of these dipoles and low frequency dispersion phenomenon were observed during impedance measurements.
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| 4. |
- Fakhar-e-Alam, M, et al.
(författare)
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Role of ALA sensitivity in HepG2 cell in the presence of diode laser
- 2011
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Ingår i: LASER PHYSICS. - : Springer Science Business Media. - 1054-660X. ; 21:5, s. 972-980
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Tidskriftsartikel (refereegranskat)abstract
- 5-aminolevulinic acid (ALA) being an amazing second generation photosensitizer was studied as photodamaging drug on hepatocellular carcinoma (HepG2) cells. The mentioned photosensitizer is converted to PpIX in HepG2 cells in vitro, inducing haem in the cell causing generation of singlet oxygen leading to cell apoptosis. Cell uptake of 5-ALA was evaluated with different concentrations (ranging from 0-800 mu g/ml) for 0-49 h incubation period. ALA administered in HepG2 cells is converted into Protoporphyrin IX (PpIX) which has a short half life and constitute a good hematoporphyrin derivative (HPD). Cytotoxicity of ALA in dark and cellular viability without ALA in the presence of light was studied, showing minimal toxic effects in dark with no photodamaging effect on mentioned cells in absence of ALA were observed. The optimal uptake of photosensitizer (5-ALA) in HepG2 cells was investigated by means of spectrophotometeric measurements, cellular viability was determined by means of neutral red assay (NRA). It was observed that with different concentrations (0-800 mu g/ml) of ALA or light doses (0-160 J/cm(2)), there were no significant effect on cellular viability when studied independently. The novel of photocytotoxic study indicates that light dose of 120 J/cm(2) produces convincing Photodynamic therapy (PDT) results for HepG2 cells incubated with 262 mu g/ml of 5-ALA deducting that HepG2 cell line is sensitive to ALA mediated PDT. Finally morphological changes in HePG2 cells were determined before and after ALA-mediated PDT by confocal microscopy.
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| 5. |
- Imran, Z., et al.
(författare)
-
Excellent humidity sensing properties of cadmium titanate nanofibers
- 2013
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 39:1, s. 457-462
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Tidskriftsartikel (refereegranskat)abstract
- We report humidity sensing characteristics of CdTiO3 nanofibers prepared by electrospinning. The nanofibers were porous having an average diameter and length of similar to 50-200 nm and similar to 100 mu m, respectively. The nanofiber humidity sensor was fabricated by defining aluminum electrodes using photolithography on top of the nanofibers deposited on glass substrate. The performance of the CdTiO3 nanofiber humidity sensor was evaluated by AC electrical characterization from 40% to 90% relative humidity at 25 degrees C. The frequency of the AC signal was varied from 10(-1) to 10(6) Hz. Fast response time and recovery time of 4 s and 6 s were observed, respectively. The sensor was highly sensitive and exhibited a reversible response with small hysteresis of less than 7%. Long term stability of the sensor was confirmed during 30 day test. The excellent sensing characteristics prove that the CdTiO3 nanofibers are potential candidate for use in high performance humidity sensors.
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| 6. |
- Kashif, M., et al.
(författare)
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Effect of Different Seed Solutions on the Morphology and Electrooptical Properties of ZnO Nanorods
- 2012
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Ingår i: Journal of Nanomaterials. - : Hindawi Publishing Corporation. - 1687-4110 .- 1687-4129. ; 2012:452407
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Tidskriftsartikel (refereegranskat)abstract
- The morphology and electrooptical properties of ZnO nanorods synthesized on monoethanolamine-based seed layer and KOH-based seed layer were compared. The seed solutions were prepared in monoethanolamine in 2-methoxyethanol and potassium hydroxide in methanol, respectively. Zinc acetate dihydrate was as a common precursor in both solutions. The nanorod-ZnOs were synthesized via the spin coating of two different seed solutions on silicon substrates followed by their hydrothermal growth. The scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), and Raman studies revealed that the ZnO nanorods obtained from monoethanolamine-based seed layer had fewer defects, better crystals, and better alignment than those realized via KOH-based seed layer. However, the current-voltage (I-V) characteristics demonstrated better conductivity of the ZnO nanorods obtained via KOH-based seed layer. The current measured in forward bias was 4 mA and 40 mu A for ZnO-nanorods grown on KOH-based seed layer and monoethanolamine-based with the turn on voltage of approximately 1.5 V and 2.5V, respectively, showing the feasibility of using both structures in optoelectric devices.
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| 7. |
- Batool, S S., et al.
(författare)
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Investigation of dielectric relaxation behavior of electrospun titanium dioxide nanofibers using temperature dependent impedance spectroscopy
- 2013
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Ingår i: Ceramics International. - : Elsevier. - 0272-8842 .- 1873-3956. ; 39:2, s. 1775-1783
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Tidskriftsartikel (refereegranskat)abstract
- The electrospinning method has been utilized in the fabrication of titanium dioxide nanofibers (TNFs) with an average diameter of similar to 50 nm and length of 100 um. Effect of temperature on the dielectric relaxation behavior of the fabricated nanofibers have been studied using AC impedance spectroscopy. The morphological, structural and compositional aspects as well as the optical properties of the TNFs have been investigated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive x-ray spectroscopy (EDX) and ultraviolet visible (UV vis) absorption spectrum. The permittivity behavior of the device at the frequency below 10(2) Hz shows the relaxation contribution along with the electrode polarization. Dielectric loss peak in loss tangent also confirms the presence of relaxing dipoles in TNFs. The AC conductance as a function of frequency confirms the semiconducting nature of TNFs and obeys Jonschers power law except a small deviation in the low frequency region. DC conductivity increases with increase in temperature.
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| 8. |
- Bruce, SPO, et al.
(författare)
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Design and realization of a millimeter-wave Si/SiGe HBT frequency multiplier
- 1998
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Ingår i: IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9480. ; 46:5, s. 695-700
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the design of an active millimeterwave frequency doubler using an Si/SiGe heterojunction bipolar transistor (HBT) as the active device is studied. Simulations are made using a developed physics-based large-signal model for Si/SiGe HBT's, wh
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| 9. |
- Fakhar-E-Alam, Muhammad, et al.
(författare)
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RETRACTED: Empirical Modeling of Physiochemical Immune Response of Multilayer Zinc Oxide Nanomaterials under UV Exposure to Melanoma and Foreskin Fibroblasts
- 2017
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Carcinogenesis is a complex molecular process starting with genetic and epigenetic alterations, mutation stimulation, and DNA modification, which leads to proteomic adaptation ending with an uncontrolled proliferation mechanism. The current research focused on the empirical modelling of the physiological response of human melanoma cells (FM55P) and human foreskin fibroblasts cells (AG01518) to the multilayer zinc oxide (ZnO) nanomaterials under UV-A exposure. To validate this experimental scheme, multilayer ZnO nanomaterials were grown on a femtotip silver capillary and conjugated with protoporphyrin IX (PpIX). Furthermore, PpIX-conjugated ZnO nanomaterials grown on the probe were inserted into human melanoma (FM55P) and foreskin fibroblasts cells (AG01518) under UV-A light exposure. Interestingly, significant cell necrosis was observed because of a loss in mitochondrial membrane potential just after insertion of the femtotip tool. Intense reactive oxygen species (ROS) fluorescence was observed after exposure to the ZnO NWs conjugated with PpIX femtotip model under UV exposure. Results were verified by applying several experimental techniques, e.g., ROS detection, MTT assay, and fluorescence spectroscopy. The present work reports experimental modelling of cell necrosis in normal human skin as well as a cancerous tissue. These obtained results pave the way for a more rational strategy for biomedical and clinical applications.
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| 10. |
- Fakhar-e-Alam, M., et al.
(författare)
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Tumoricidal Effects of Nanomaterials in HeLa Cell Line
- 2011
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Ingår i: Laser physics. - : MAIK Nauka/Interperiodica. - 1054-660X .- 1555-6611. ; 21:11, s. 1978-1988
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Tidskriftsartikel (refereegranskat)abstract
- The current study exhibits the cellular response of HeLa (cervical cancer) cells to metal oxides ultrafine nanomaterials e.g. manganese dioxide nanowires (MnO(2) NRs), iron oxide nanoparticles (Fe(2)O(3) NPs) and zinc oxide nanorods (ZnO NRs) as bare and as conjugated with photosensitizers. For cytotoxic evaluations, the cellular morphology, (MTT) assay, reactive oxygen species (ROS) production were used for cases with and without photo sensitizer as well illuminated with UV-visible laser exposed conditions. Three different photosensitizers were tested. These are 5-aminolevulinic acid (5-ALA), Photofrin (R), and protoporphyrin dimethyl ester (PPDME). Significant loss in cell viability was noted with 100-500 mu g/ml in bare and conjugated forms of the metal oxides used. The effect was insignificant with lower concentrations (0.05-50 mu g/ml). While notable anticancer effect of 5-ALA under 30 J/cm(2) of diode laser irradiation was noted as compared to other photo sensitizer. By increasing the UV irradiation time of labeled cells, generation of ROS was observed, indicating the possibility of achieving efficient photodynamic therapy (PDT).
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