1,721,051 research outputs found
In situ tailoring the morphology of In(OH)(3) nanostructures via surfactants during anodization and their transformation into In2O3 nanoparticles
No full textThe present work reports the effect of various surfactants on the morphology of In(OH)(3) nanostructures prepared via anodization. In-sheets were anodized in an environmentally benign electrolyte containing a small quantity of CTAB, CTAC, and PDDA surfactants at room temperature. The produced nanostructures were characterized using XRD, HRTEM, SAED, and EDAX. The morphology of indium hydroxide (In(OH)(3)) nanostructures was successfully tailored in situ with the help of surfactants in 1 M KCl aqueous electrolyte. XRD results confirmed the formation of In(OH)(3) and indium oxyhydroxide (InOOH) nanostructures in the pristine form which were transformed into single-phase cubic In2O3 nanoparticles (NPs) after calcination. HRTEM analyses showed that the morphology and size of the In(OH)(3) nanostructures can be tuned to form nanorods, nanosheets and nanostrips using different surfactants. The results revealed that CTAC and PDDA surfactants have a profound effect on the morphology of In(OH)(3) nanostructure compared to CTAB due to the higher concentration of Cl- ion. The possible mechanism of surfactants effect on the morphology is proposed. Furthermore, annealing converted the In(OH)(3) nanostructures into spherical In2O3 NPs with uniform and homogeneous size. We anticipate that the morphology of other metal-oxides nanostructure can be tuned using this simple, facile and rapid technique. In2O3 NPs prepared without and with CTAB surfactant were further explored for the non-enzymatic detection of hydrogen peroxide (H2O2). Electrochemical measurements showed enhanced electrocatalytic performance with fast electron transfer (similar to 2s) between the redox centers of H2O2 and electrode surface. The In2O3 NPs prepared using CTAB/Au electrode exhibited about 4-fold increase in sensitivity compared to the bare Au electrode. The biosensor also demonstrated good reproducibility, higher selectivity, and increased shelf life.
Repurposing FDA approved drugs against monkeypox virus DNA dependent RNA polymerase: virtual screening, normal mode analysis and molecular dynamics simulation studies
No full textZoonotic monkeypox disease, caused by the double-stranded DNA monkeypox virus, has become a global concern. Due to the absence of a specific small molecule drug for the disease, this report aims to identify potential inhibitor drugs for monkeypox. This study explores a drug repurposing strategy using virtual screening to evaluate 1615 FDA approved drugs against the monkeypox virus DNA dependent RNA polymerase subunit A6R. Normal mode analysis and molecular dynamics simulation assessed the flexibility and stability of the target protein in complex with the top screened drugs. The analysis identified Nilotinib (ZINC000006716957), Conivaptan (ZINC000012503187), and Ponatinib (ZINC000036701290) as the most potential RNA polymerase inhibitors with binding energies of - 7.5 kcal/mol. These drugs mainly established hydrogen bonds and hydrophobic interactions with the protein active sites, including LEU95, LEU90, PRO96, MET110, and VAL113, and residues nearby. Normal mode analysis and molecular dynamics simulation confirmed the stability of interactions between the top drugs and the protein. In conclusion, we have discovered promising drugs that can potentially control the monkeypox virus and should be further explored through experimental assays and clinical trials to assess their actual activity against the disease. The findings of this study could lay the foundation for screening repurposed compounds as possible antiviral treatments against various highly pathogenic viruses
Visible and infrared emission from Er₂O₃ nanoparticles, and Ho⁺³, Tm⁺³, and Sm⁺³ doped in AlN for optical and biomedical applications
No full textRare-earth ions holmium (Ho+3), Thulium (Tm+3), and Samarium (Sm+3) were investigated for
infrared emission and their possible biomedical applications by a photoluminescence (PL)
system. Holmium’s (Ho+3) emission peaks were the result of transitions
5
S2 →
5
I7,
and
5
S2 →
5
I5
respectively. Samarium’s (Sm+3) emission peaks were 936 nm and 1863 nm. Thulium’s (Tm+3)
emission peaks were the a result of transitions
3
H4 →
3
H6,
3
H5 →
3
H6 , and
3
F4 →
3
H6 respectively.
Erbium Oxide nanoparticles (Er2O3) mixed with water by a photoluminescence (PL) system.
Erbium Oxide’ (Er2O3) nanoparticle’s emission peaks were the a result of transitions
4
I15/2 →
4
S3/2
,
4
I15/2 →
4
I13/2 respectively. The process was also repeated in vacuum and it was found that
the green emission enhances tremendously when the nanoparticles are excited in vacuum. This
enhanced luminescence from the Erbium Oxide nanoparticles shows their potential importance
in the optical devices and Biomedical applications.Thesis (M.S.)Department of Physics and Astronom
Radiation shielding and protection by MCP-200 alloy
No full textRadiation can be used to target specific parts of the body to treat cancer. Different forms of shielding material help to ensure that the radiation only reaches the targeted areas and does not damage healthy cells. Therefore, it is important to study how different materials interact with radiation.
There will be two methods of interaction that will be discussed. The first method of interaction is the attenuation of a radiation beam. When radiation passes through a material, the intensity of the beam decreases with thickness of the material. How quickly it decreases depends on the material and the energy of the beam. The attenuation of a beam of radiation is an exponentially decreasing function of thickness. The quantity that determines how fast radiation decreases in a medium is referred to as the attenuation coefficient. Measuring the attenuation coefficient allows one to determine how much radiation has passed through a material of given thickness.
The second method of interaction is referred to as buildup. The buildup of radiation is an increase in dosage of a radioactive sample due to Compton Scattering. Buildup is determined by the material the radiation beam is passing through and energy of the radiation beam, just as the attenuation was. The quantity that determines how much the radiation beam’s dosage has increased is referred to as the buildup factor. The buildup factor is multiplied by the exponentially decaying function (determined from the attenuation) to give a more complete equation for radiation. The buildup factor is greater than or equal to one. It can never be less than one, as this would imply that the buildup is decreasing the dosage. If the buildup factor is equal to one. Then this shows that there is no buildup of radiation in the material.
The goal of my research is to measure the attenuation coefficient (penetrating power) and the buildup factor of the alloy, MCP 200. Then, comparisons will be made to theoretical and computational research conducted on different materials from other papers. It was found that the buildup factor increased linearly with increasing material thickness, decreased with increasing photon energy, and increased with increasing attenuator to detector distance. It was reported in a paper that the buildup factor increased with increasing photon energy. Other papers reported that the buildup factor would first increase with increasing photon energy, reach a peak, and then begin decreasing.Thesis (M.S.)Department of Physics and AstronomyGamma-ray interactions in matter -- Radiological effects on the human body -- Experimental data -- Computer simulation
Title on signature form : Klein-Nishina electronic cross section, Compton scattering cross section, linear attenuation coefficient and build up factor of wax for radiation protection and safety
No full textbe used to target specific parts of the body to treat cancer. However, radiation can be
dangerous and can harm normal tissues if exposed to high dose for long time. Therefore,
shielding and protection of body or normal tissues is important when work in radiation area.
Different forms of shielding material help to ensure that radiation only reaches the targets and
does not damage healthy cells. To achieve the goal of safety it is important to know various
properties of shielding material before they are used practically.
The purpose of this work is to study and calculate Klein-Nishina electronic cross
section , Compton scattering cross section
, and linear attenuation coefficient μ and build up
factor B of Wax for radiation protection and safety purposes. Gamma rays of certain energies
are going to be used to calculate Klein-Nishina electronic cross-sections for wax. The cross
sections are further used to calculate Compton scattering coefficients. Build up factors will be
calculated using narrow beams and broad beams of gamma radiation under the same conditions.
Respective graph will be obtained to analyze the results obtained.Department of Physics and Astronom
Surface characterization and infrared emission from AIN : Tm film
No full textRare-earth elements contain rich structure in energy levels, ready to be exploited in structural, electronic, and optical applications. In optics, some of rare-earth elements contain long life time metastable states, which are used in laser and light amplifiers. Rare-earth ions in these applications are usually doped into silica glass, amorphous silicon, polycrystalline silicon and single crystal semiconductors. In this paper, we examine doped crystalline film of semiconductors, and characterize its crystallological and optical properties via X-ray diffraction and photoluminescence measurements. A bright, sharp response in emission spectra indicates that the film can be applied in future optical devices for optical relaying and amplification.Thesis (M.A.)Department of Physics and Astronom
Determination of the linear attenuation coefficients and buildup factors of MCP-96 alloy for use in tissue compensation and radiation protection
No full textThe linear attenuation coefficient and buildup factor are a few of the important characteristics that need to be studied and determined prior to using a material clinically in radiation treatment and protection. The linear attenuation coefficient and buildup factor, as well as several other properties, will be determined for MCP-96 alloy to assess its use in radiation therapy. A narrow collimated beam of γ-rays from sources with varying energies will pass through various thicknesses of MCP-96 alloy. The attenuation in the intensity of the beam will be determined for each varying thickness of the alloy. Plotting the thickness of the alloy versus the corresponding logarithmic intensity of the beam will allow calculation of the linear attenuation coefficient.
The narrow beam geometry will then be replaced by the broad beam geometry to determine the buildup factor. Additional radiation is obtained through the broad beam geometry as a result of scattering and secondary radiation. Comparing the broad beam geometry to the narrow beam geometry allows determination of the buildup factor. Since the buildup factor depends upon the thickness of the MCP-96 attenuator, the energy of the beam, and the source-to-attenuator (STA) distance, it will be calculated using three parameters. It will be calculated as a function of thickness of MCP-96 alloy by using various thicknesses of the alloy; as a function of the energy of the incident radiation beam by using several sources with different beam energies; and finally, as a function of the source-to-attenuator distance by changing the position of the MCP-96 attenuators.Thesis (M.A.)Department of Physics and Astronom
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Optical and luminescence properties of erbium, ytterbium and terbium doped in aluminum nitride
No full textStudies have been done to determine rare-earth elements’ optical and luminescent properties using wide bandgap nitride semiconductors as suitable hosts. Research done here will contribute to the information needed to further study rare-earth elements and their unique properties. Thin films of rare-earth elements erbium, terbium, ytterbium, and both erbium and ytterbium doped into AlN are studied by laser excitation. A 532 nm Nd: YAG green laser and 783nm crystal infrared laser are used for excitation in conjunction with a spectrometer to measure photoluminescence. With the 532 nm laser, AlN: Er emits peaks at 554 nm, 561 nm, and 1552 nm, AlN: Tb emits peaks at 549 nm and 562 nm, AlN: Yb emits peaks at 966 nm, and co-doped AlN: ErYb contains peaks including both AlN: Er and AlN: Yb. Energy transfer occurred from Er to Yb resulting in an increased magnitude and peak shift. The 783 nm laser gave peaks at 1563nm for AlN: Er, 1508 nm and 1533 nm for AlN: Tb, and 1567nm for AlN: ErYb. No detectable peaks were given for AlN: Yb. A peak shift was detected in comparison of AlN: Er and AlN: ErYb. A magnetic field of 1000 G was applied to AlN: ErYb resulting in an
increase in intensity of the major peak at 561nm with a splitting, creating a secondary peak at 564.5 nm. Biomedical applications can be used from the high penetration ability of lower wavelength lasers and the use of a magnetic field, which is not harmful to the human body. Enhanced green emission in erbium can be useful in future optical, photonic, and electrical devices.Thesis (M.S.)Department of Physics and Astronom
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