| 1. |
- Bora, Tanujjal, et al.
(författare)
-
Controlled side coupling of light to cladding mode of ZnO nanorod coated optical fibers and its implications for chemical vapor sensing
- 2014
-
Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 202, s. 543-550
-
Tidskriftsartikel (refereegranskat)abstract
- Controlled light coupling from surrounding to the cladding mode of zinc oxide (ZnO) nanorod coated multimode optical fiber induced by the light scattering properties of the nanorod coating and their applications of sensing are reported here. A dense and highly ordered array of ZnO nanorods is grown on the cladding of silica fibers by using low temperature hydrothermal process and the effect of the hydrothermal growth conditions of the nanorods on the light scattering and coupling to the optical fibers is experimentally investigated. The nanorod length and its number per unit area are found to be most crucial parameters for the optimum side coupling of light into the fibers. Maximum excitation of the cladding mode by side coupling of light is obtained with ZnO nanorods of length similar to 2.2 mu m, demonstrating average coupling efficiency of similar to 2.65%. Upon exposure to different concentrations of various chemical vapors, the nanorod coated fibers demonstrated significant enhancement in the side coupled light intensity, indicating the potential use of these ZnO nanorod coated fibers as simple, low cost and efficient optical sensors. The sensor responses to methanol, ethanol, toluene and benzene vapor were investigated and compared, while the effect of humidity in the sensing environment on the sensor performance was explored as well.
|
|
| 2. |
- Fallah, H., et al.
(författare)
-
Demonstration of side coupling to cladding modes through zinc oxide nanorods grown on multimode optical fiber
- 2013
-
Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 38:18, s. 3620-3622
-
Tidskriftsartikel (refereegranskat)abstract
- A novel concept is introduced that utilizes the scattering properties of zinc oxide nanorods to control light guidance and leakage inside optical fibers coated with nanorods. The effect of the hydrothermal growth conditions of the nanorods on light scattering and coupling to optical fiber are experimentally investigated. At optimum conditions, 5% of the incident light is side coupled to the cladding modes. This coupling scheme could be used in different applications such as distributed sensors and light combing. Implementation of the nanorods on fiber provides low cost and controllable nonlithography-based solutions for free space to fiber coupling. Higher coupling efficiencies can be achieved with further optimization.
|
|
| 3. |
- Sharma, Rohan, et al.
(författare)
-
Rare X Chromosome Abnormalities in Systemic Lupus Erythematosus and Sjogrens Syndrome
- 2017
-
Ingår i: Arthritis & Rheumatology. - : WILEY. - 2326-5191 .- 2326-5205. ; 69:11, s. 2187-2192
-
Tidskriftsartikel (refereegranskat)abstract
- Objective. Sjogrens syndrome (SS) and systemic lupus erythematosus (SLE) are related by clinical and serologic manifestations as well as genetic risks. Both diseases are more commonly found in women than in men, at a ratio of similar to 10 to 1. Common X chromosome aneuploidies, 47,XXY and 47,XXX, are enriched among men and women, respectively, in either disease, suggesting a dose effect on the X chromosome. Methods. We examined cohorts of SS and SLE patients by constructing intensity plots of X chromosome single-nucleotide polymorphism alleles, along with determining the karyotype of selected patients. Results. Among similar to 2,500 women with SLE, we found 3 patients with a triple mosaic, consisting of 45,X/46,XX/47,XXX. Among similar to 2,100 women with SS, 1 patient had 45,X/46,XX/47,XXX, with a triplication of the distal p arm of the X chromosome in the 47,XXX cells. Neither the triple mosaic nor the partial triplication was found among the controls. In another SS cohort, we found a mother/daughter pair with partial triplication of this same region of the X chromosome. The triple mosaic occurs in similar to 1 in 25,000-50,000 live female births, while partial triplications are even rarer. Conclusion. Very rare X chromosome abnormalities are present among patients with either SS or SLE and may inform the location of a gene(s) that mediates an X dose effect, as well as critical cell types in which such an effect is operative.
|
|
| 4. |
- Bhatt, Pramod, et al.
(författare)
-
Correlation of structural, chemical and magnetic properties in annealed Ti/Ni multilayer structures
- 2005
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 97:4, s. 043509-
-
Tidskriftsartikel (refereegranskat)abstract
- Ti/Ni multilayer samples have been synthesized on float glass substrates using an electron-beam evaporation technique under ultrahigh vacuum conditions at room temperature. Grazing incidence x-ray diffraction (GIXRD) and grazing incidence x-ray reflectivity (GIXRR) techniques were used, respectively, to study structural modifications and to determine corresponding changes in microstructural parameters, such as individual layer thickness, interface roughness, and electron density due to annealing treatment. In addition to this, the chemical nature of the surface and interfaces of these samples were also studied using a depth profile x-ray photoelectron spectroscopy (XPS) technique. The GIXRD measurement show clear amorphization of the as-deposited multilayer sample annealed in the temperature range of 300–400 °C. The corresponding GIXRR measurement indicates the formation of a sufficiently thick layer of Ti–Ni at interfaces converting the Ti/Ni bilayer into a Ti/Ti–Ni/Ni trilayer multilayer structure. The precipitation of the Ti–Ni alloy phase at the interface in the case of samples annealed at 400 °C has been confirmed by XPS measurements. The magnetization behavior investigated using the magneto-optical Kerr effect technique clearly shows well the saturation magnetization behavior for all samples annealed up to 300 °C, while the sample annealed at 400 °C does not show saturation magnetization. The corresponding coercivity value (Hc) is also found to be changed drastically from 15.5 to 0.6 Oe. This observed magnetization behavior is discussed and correlated with structural and chemical changes in the multilayer structure.
|
|
| 5. |
- Bhatt, Pramod, et al.
(författare)
-
Effect of phase formation on valence band photoemission and photoresonance study of Ti/Ni multilayers using synchrotron radiation
- 2006
-
Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 15:1-2, s. 56-66
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents investigation of Ti–Ni alloy phase formation and its effect on valence band (VB) photoemission and photoresonance study of as-deposited as well as annealed Ti/Ni multilayers (MLs) up to 600 °C using synchrotron radiation. For this purpose [Ti (50 Å)/Ni (50 Å)]X10 ML structures were deposited by using electron-beam evaporation technique under ultra-high vacuum (UHV) conditions. Formation of different phases of Ti–Ni alloy due to annealing treatment has been confirmed by the X-ray diffraction (XRD) technique. The XRD pattern corresponding as-deposited ML sample shows crystalline nature of both Ti and Ni deposited layers, whereas 300 °C annealed ML sample show solid-state reaction (SSR) leading to amorphization and subsequent recrystallisation at higher temperatures of annealing (≥400 °C) with the formation of TiNi, TiNi3 and Ti2Ni alloy phases. The survey scans corresponding to 400, 500 and 600 °C annealed ML sample shows interdiffusion and intermixing of Ni atoms into Ti layers leading to chemical Ti–Ni alloys phase formation at interface. The corresponding recorded VB spectra using synchrotron radiation at 134 eV on as-deposited ML sample with successive sputtering shows alternately photoemission bands due to Ti 3d and Ni 3d, respectively, indicating there is no mixing of the consequent layers and any phase formation at the interface during deposition. However, ML samples annealed at higher temperatures of annealing, particularly at 400, 500 and 600 °C show a clear shift in Ni 3d band and its satellite peak position to higher BE side indicates Ti–Ni alloy phase formation. In addition to this, reduction of satellite peak intensity and Ni 3d density of states (DOS) near Fermi level is also observed due to Ti–Ni phase formation with higher annealing temperatures. The variable photon energy VB measurements on as-deposited and ML samples annealed at 400 °C confirms existence and BE position of observed Ni 3d satellite structure. The observed changes and modifications in the VB photoemission are discussed and interpreted in terms of structural changes at the interface due to annealing treatment.
|
|
| 6. |
- Bhatt, Pramod, et al.
(författare)
-
High temperature annealing effect on structural and magnetic properties of Ti/Ni multilayer
- 2006
-
Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 253:5, s. 2572-2580
-
Tidskriftsartikel (refereegranskat)abstract
- High temperature annealing effect on structural and magnetic properties of Ti/Ni multilayer (ML) up to 600 °C have been studied and reported in this paper. Ti/Ni multilayer samples having constant layer thicknesses of 50 Å each are deposited on float glass and Si(1 1 1) substrates using electron-beam evaporation technique under ultra-high vacuum (UHV) conditions at room temperatures. The micro-structural parameters and their evolution with temperature for as-deposited as well as annealed multilayer samples up to 600 °C in a step of 100 °C for 1 h are determined by using X-ray diffraction (XRD) and grazing incidence X-ray reflectivity techniques. The X-ray diffraction pattern recorded at 300 °C annealed multilayer sample shows interesting structural transformation (from crystalline to amorphous) because of the solid-state reaction (SSR) and subsequent re-crystallization at higher temperatures of annealing, particularly at ≥400 °C due to the formation of TiNi3 and Ti2Ni alloy phases. Sample quality and surface morphology are examined by using atomic force microscopy (AFM) technique for both as-deposited as well as annealed multilayer samples. In addition to this, a temperature dependent dc resistivity measurement is also used to study the structural transformation and subsequent alloy phase formation due to annealing treatment. The corresponding magnetization behavior of multilayer samples after each stage of annealing has been investigated by using Magneto-Optical Kerr Effect (MOKE) technique and results are interpreted in terms of observed micro-structural changes.
|
|
| 7. |
- Bhatt, Pramond, et al.
(författare)
-
Influence of Ti layer thickness on solid state amorphization and magnetic properties of annealed Ti/Ni multilayer
- 2007
-
Ingår i: Journal of Physics Condensed Matter. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 37:19, s. 376210-
-
Tidskriftsartikel (refereegranskat)abstract
- Annealing induced SSR (solid state reaction) leading to amorphization and magnetic properties as a function of Ti layer thickness has been investigated using XRD (x-ray diffraction), GIXRR (grazing incidence x-ray reflectivity) and MOKE (magneto-optical Kerr effect) measurements. [Ti(t Å)/Ni(50 Å)] × 10 ML samples where t = 30, 50 and 70 Å have been prepared by using electron beam evaporation technique under ultra-high vacuum conditions at room temperature. The amorphization process was carefully studied using XRD and GIXRR techniques showing that the SSA (solid state amorphization) temperature gradually decreases with increasing Ti layer thickness. Corresponding MOKE measurements show a magnetic to non-magnetic transition near the amorphization temperature (TA) with annealing, for each of the Ti layer thicknesses, due to crystalline Ti–Ni alloy phase formation at interfaces. The saturation magnetization and coercivity were also modified with Ti layer thickness variation. In addition to this, anisotropy developed with Ti layer thickness and diminished with increasing annealing temperatures. All these magnetic changes due to Ti layer thickness variations are interpreted in terms of amorphization and micro-structural changes near the SSA temperature.
|
|
| 8. |
- Chaudhari, M. B., et al.
(författare)
-
Chromatic tuning of plasmon resonance of tri-layered composites : Silver, gold and copper nanoparticles for optical thin film colour filter
- 2012
-
Ingår i: Micro & Nano Letters. - : Institution of Engineering and Technology. - 1750-0443. ; 7:2, s. 146-148
-
Tidskriftsartikel (refereegranskat)abstract
- The authors describe an approach to control colour shades by varying the volume fractions of three metal nanoparticles (NPs), Cu, Au and Ag, of fixed size and shape. The NPs were designed to match the absorption peaks of the three primary colours. Using the dynamic Maxwell Garnett equation, an analytical model is extracted that calculates the volume fraction value of each metal for the desired transmission red, green and blue values. The model considers the cross-talk between colours because of the broadening of the plasmon peaks. Maximum error of 10% was observed when producing secondary colour and grey shades.
|
|
| 9. |
- Karim, F., et al.
(författare)
-
Optical fiber-based sensor for in situ monitoring of cadmium sulfide thin-film growth
- 2013
-
Ingår i: Optics Letters. - : Optical Society of America. - 0146-9592 .- 1539-4794. ; 38:24, s. 5385-5388
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents a scheme for in situ monitoring of thin-film growth. A fiber-optic sensor based on Fabry-Perot interferometric technique has been established for the first time to monitor in situ growth of thin films. This was applied for determining thickness of cadmium sulfide (CdS) thin films during growth. The fabrication process of CdS film was carried out in 30mMcadmiumacetate and thioacetamide solution at 60°C temperature. The estimated thickness determined during the growth was verified by scanning electron microscopy. This study shows that in situ measurement of the thickness of thin films is feasible by this new technique, and a close match of the estimated thickness was achieved.
|
|
| 10. |
- Kitsomboonloha, R., et al.
(författare)
-
Plasmon resonance tuning of gold and silver nanoparticle-insulator multilayered composite structures for optical filters
- 2011
-
Ingår i: Micro & Nano Letters. - : IEEE. - 1750-0443. ; 6:6, s. 342-344
-
Tidskriftsartikel (refereegranskat)abstract
- A novel approach for optical filter implementation by tuning the plasmon resonance absorption of gold and silver nanoparticles in layer-by-layer (LBL) composite structures is presented. The LBL composite structures consisted of alternating layers of polyacrylic acid (PAA)-capped Au and PAA-capped Ag bi-layers. The results show clear spectrum tuning of green and blue peaks. Spectrum tuning can be extended when more metals or oxide nanoparticles are incorporated.
|
|
