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610 results on '"Singh, F."'

64. Investigation of the precipitation kinetics and changes of magnetic anisotropy of iron particles in ion-irradiated silica gel films by means of electron-spin resonance

Author

Pivin, J.C., Esnouf, S., Singh, F., and Avasthi, D.K.

Subjects
Anisotropy -- Usage, Iron compounds -- Electric properties, Iron compounds -- Magnetic properties, Silica gel -- Electric properties, Silica gel -- Magnetic properties, Dielectric films -- Electric properties, Dielectric films -- Magnetic properties, Thin films -- Electric properties, Thin films -- Magnetic properties, Physics
Abstract

The effect of the density of ion-induced electronic excitations on the nucleation of Fe particles in a silicon-based gel and on the magnetic ordering in SiO2:Fe composites with a volume fraction of metal of a few percent derived from the same gel is examined. Irradiation-induced changes in the magnetic anisotropy of composite films depend on the order of magnitude of electronic energy loss S(sub e).

Published
2005

65. Modifications of ZnO thin films under dense electronic excitation

Author

Kumar, P.M. Ratheesh, Kartha, C. Sudha, Singh, F., Avasthi, D.K., Abe, T., Kashiwaba, Y., Okram, G.S., Kumar M., and Kumar, Sarvesh

Subjects
Dielectric films -- Research, Thin films -- Research, Zinc oxide -- Optical properties, X-rays -- Diffraction, X-rays -- Usage, Physics
Abstract

The spray pyrolyzed ZnO film samples are irradiated using 120 MeV Au ion beam and then characterized using optical absorption and transmission, x-ray diffraction (XRD), electrical resistivity measurements, x-ray photoelectron spectroscopy (XPS), and photoluminescence studies. Details of the effects of irradiation, intensity of peaks of XRD and photoluminescence, electrical restivity of the films, atomic concentration form XPS analysis and variations in carrier concentration are discussed.

Published
2005

66. Structure and photoluminescence studies of ZnS:Mn nanoparticles

Author

Karar, N., Singh, F., and Mehta, B. R.

Subjects
Sulfides -- Electric properties, Zinc compounds -- Electric properties, Photoluminescence -- Analysis, Physics
Abstract

ZnS:Mn is produced in nanocrystalline form by a chemical method using polyvinylpyroledone as a chemical capping agent. The study shows that the prepared pure MnS samples did not show any photoluminescence at room temperature and concludes that the observed photoluminescence is Mn(super 2+) induced in nanocrystalline ZnS host.

Published
2004

67. Investigation of radiation damage using thermal spike model for SHI irradiation on Al2O3.

Author

Patra, Paramita, Shah, Sejal, Toulemonde, M., Sulania, I., and Singh, F.

Subjects
RADIATION damage, NUCLEAR energy, ALUMINUM oxide, ATOMIC force microscopy, IRRADIATION, ION beams
Abstract

The material exposed to energetic radiation may change its properties and performance. Ion beam irradiation is an established method to investigate radiation damage in materials. In the present study, SRIM code is employed as a tool to determine the electronic and nuclear energy losses and displacement per atom (DPA) associated with the damage induced in Al2O3 using 100 MeV Au ion. We have further studied the creation of 100 MeV Au ion induced molten zone along the ion track in Al2O3 in the framework of the thermal spike (TS) model. Using the in-elastic thermal spike model, elastic thermal spike model, and unified thermal spike model, the evolution of lattice temperature and latent track radius as a function of depth of Al2O3 for 100 MeV Au ion irradiation are investigated. The current results demonstrate that the latent track radius shows a U-shaped variation based on the combined effect of electronic stopping power and nuclear stopping power. In order to corroborate these results, an additional irradiation experiment was performed using swift heavy ion (SHI), 100 MeV Au ions with fluence 1×1014 ions/cm2 for Al2O3. To investigate the structural properties, surface morphology and to identify the defects in the samples, pristine and irradiated Al2O3 samples were characterized by Grazing Incident X-Ray Diffraction (GIXRD), Atomic Force Microscopy (AFM) and Photoluminescence Spectroscopy (PL). AFM study shows the increase in roughness after SHI irradiation. A decrease in intensity of PL spectra upon SHI irradiation indicates the formation of new defects and disordered structures in the material, which is quite in agreement with the theoretical results. [ABSTRACT FROM AUTHOR]

Published
2022
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93. Self-reported asthma diagnosis and mental health: Findings from the Collaborative Psychiatric Epidemiology Surveys

Author

Hans Oh, Stickley A, Singh F, and Koyanagi A

Subjects
Anxiety, Alcohol use, Asthma, Race, Substance use, Depression
Abstract

Historically, asthma has had a mixed association with mental health. More research is needed to examine the associations between asthma and specific psychiatric disorders, and whether these associations hold true across racial groups in the general population of the United States. Using the Collaborative Psychiatric Epidemiology Surveys, we examined the associations between lifetime asthma and specific DSM-IV psychiatric disorders, adjusting for sociodemographic characteristics and smoking status. We found that when looking at the entire sample, self-reported diagnosis of asthma was associated with greater odds of reporting mood disorders (AOR: 1.36; 95% CI: 1.05-1.74). Asthma was not significantly associated with total anxiety disorders (AOR 1.25; 95% CI: 0.98-1.60), though it was specifically associated with generalized anxiety disorder. Asthma was associated with greater odds of having alcohol use disorders (AOR: 1.71; 95% CI: 1.24-2.37), but was not associated with total eating disorders (AOR:1.36; 95% CI: 1.17-2.51) (though it was significantly associated with higher odds for binge eating disorder, but lower odds of reporting bulimia). The strength and the significance of the associations between asthma and psychiatric disorders varied when stratified by race, underscoring the importance of examining race as a potential explanation for the mixed findings observed previously in the literature.

Published
2019

94. High temperature-mediated rocksalt to wurtzite phase transformation in cadmium oxide nanosheets and its theoretical evidence

Author

Das, Arkaprava, Saini, C. P., Singh, D., Ahuja, Rajeev, Kaur, Anumeet, Aliukov, Sergei, Shukla, D., Singh, F., Das, Arkaprava, Saini, C. P., Singh, D., Ahuja, Rajeev, Kaur, Anumeet, Aliukov, Sergei, Shukla, D., and Singh, F.

Abstract

Herein, a high temperature-induced phase transformation (PT) in chemically grown CdO thin films is demonstrated, and its corresponding electronic origin further investigated by density functional theory. In particular, the cubic rocksalt to hexagonal wurtzite PT in the CdO thin film annealed at 900 degrees C was confirmed by X-ray diffraction (XRD), which was consistent with the high-resolution transmission electron microscopy (TEM) results. Moreover, atomic force microscopy and scanning electron microscopy clearly evidenced the morphological evolution via the formation of a nanosheet network in the wurtzite-phase CdO film. The high temperature treatment also led to a significant enhancement in the optical band gap from 2.2 to 3.2 eV, as manifested by UV-visible spectroscopy. The enhanced surface roughness of the nanosheet caused a deviation in the net dipole moment, which may break the polarizable bonds and help in reducing the average dielectric constant, resulting in a band gap opening for the transformed phase. Furthermore, X-ray absorption spectroscopy at the oxygen k-edge revealed a notable shift in the inflection point of the absorption edge, while the X-ray photoelectron spectroscopy (XPS) Cd 3d and O 1s spectra suggested a gradual reduction in the CdO2 phase with an increase in annealing temperature. In addition, different complementary techniques including Rutherford backscattering and Raman spectroscopy were exploited to understand the aforementioned PT and its structural correlation. Finally, molecular dynamics simulation together with density functional theory calculation suggested that the symmetry modification at the Brillouin zone boundary provides a succinct signature for the PT in the CdO thin film.

Published
2019
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95. Identification of tolerant genotypes against pulse beetle as a source to reduce post harvest losses in pigeonpea [Cajanus cajan (L.) Millisp.]

Author

Satheesh Naik, S.J., Lamichaney, A., Bohra, A., Mishra, R.K., Singh, F., Datta, D., Singh, I.P., Singh, N.P., Satheesh Naik, S.J., Lamichaney, A., Bohra, A., Mishra, R.K., Singh, F., Datta, D., Singh, I.P., and Singh, N.P.

Abstract

The present study intends to screen 52 pigeonpea genotypes for bruchid infestation under controlled conditions using no-choice assay. The results revealed significant differences among the genotypes considering parameters like growth index (GI), egg numbers and adult emergence. The genotypes viz., ICP 89049, IPA 37 and Dholi dwarf DB had low average values for GI (0.45, 0.48 and 0.48 respectively), number of eggs after 20 days (14.5, 21.5 and 28), and adults emerged after 30 days of oviposition (9.0, 7.0 and 4.5, respectively) when compared to the genotypes Asha (higher GI: 1.10), and IPA 7–6 (having 98.0 eggs after 20 days of incubation). Concerning associations among different traits, the GI had significant positive correlations with number of eggs laid (0.484), and number of adults emerged at 15–30 days (0.638). The GI showed a negative relationship with proportion of seed coat (–0.162) and seed hardness (–0.197). The traits that are less preferred by the bruchids include hard seed with less seed diameter and high proportion of seed coat. The tolerant genotypes viz. ICP 89049, IPA 37 and Dholi dwarf DB identified here could be deployed in breeding programs for reducing post harvest losses in pigeonpea.

Published
2019

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