Masters Dissertations : Laserhttps://repository.sustech.edu/handle/123456789/13032024-03-28T17:06:52Z2024-03-28T17:06:52ZPhotobleaching of anthocyanins using tunable dye laserAhmed,Wafa OmerSupervisor, - Ahmed Hassan S. Elkheirhttps://repository.sustech.edu/handle/123456789/23822016-01-28T06:48:06Z2008-08-01T00:00:00ZPhotobleaching of anthocyanins using tunable dye laser
Ahmed,Wafa Omer; Supervisor, - Ahmed Hassan S. Elkheir
The flowers of Hibiscus sabdarifa were extracted with acidified
methanol. The Anthocyanin of Hibiscus sabdarifa was obtained as red
needles from absolute ethanol.
A dye laser operating at 520 nm was used to bleach the red-
colored anthocyanin. A mixture of the anthocyanin and triethylamine
was irradiated with laser for 40 minutes. Under such conditions the
iv
The anthocyanin then oxidizes triethylamine and reduces to a colourless
.radical
AS
1
*AS
3
hν
0AS
1*
)(Red
3*AS• + •NR
3
3AS* +:NR
)(Colourless
Thesis
2008-08-01T00:00:00ZComparison of the Effect of Different Lasers Wavelengths and Powers on Teeth BleachingMohamed, Setana Abd alhiSupervisor, -Ali Abdel Rahman Saeed Maroufhttps://repository.sustech.edu/handle/123456789/212452018-08-05T08:16:50Z2017-12-03T00:00:00ZComparison of the Effect of Different Lasers Wavelengths and Powers on Teeth Bleaching
Mohamed, Setana Abd alhi; Supervisor, -Ali Abdel Rahman Saeed Marouf
Lasers have been long introduced in dentistry. Today lasers are been used for Endodontic, Periodontal, Oral Surgery as well as restorative procedures. Here, the effect of different wavelengths on teeth bleaching and in pulp temperature was investigated.
Teeth were exposure to diode lasers with 532 nm, 820 nm, 915 nm and continue Nd: YAG 1064nm laser in different exposure times specifically (30, 40, 50, and 60) second, the degree of staining after bleaching was evaluated, and the effects of laser bleaching in pulp temperature with and without gel during exposure to laser beam was determined.
The results led to the conclusion that the temperature rises with increasing wavelength, power, and exposure time, whereas using gel shows lower rise in temperature.
Finally, this study stated some recommendations, one of the most important recommendations don’t use high power in the bleaching process because the tooth will damage.
Thesis
2017-12-03T00:00:00ZQuality Assessment of Medical Heparin Using Laser Scattering TechniqueMohammed, Ebdaa SalahudeenSupervisor, -Nafie A. Almuslethttps://repository.sustech.edu/handle/123456789/207532018-04-22T06:50:30Z2018-02-09T00:00:00ZQuality Assessment of Medical Heparin Using Laser Scattering Technique
Mohammed, Ebdaa Salahudeen; Supervisor, -Nafie A. Almuslet
In this work, the goodness of the medical Heparin (concentration) was checked using the principle of laser scattering. A simple setup consists of diode laser with wavelength 532 nm and output power of 100 mW and USB spectrometerwere used to record the laser scattered intensity at angles of (〖45〗^°,〖90〗^° and 〖135〗^°). First of all, the relation between the concentration of the standard sample (NaCl) and the scattered laser intensity in these angles was pointed. Then the relation between the heparin concentration and the intensity of the scattered laser light was deduced for the three angles. The results showed that the relation between the angular scattered intensity and the sample concentration is a linear relation.
This study proved that this setup was sensitive and efficient indiscovering any change in the sample concentration and any manipulation in theconcentrationof Heparin, so the goodness of Heparin can be checked.
Thesis
2018-02-09T00:00:00ZDetermination of the optical properties of fabricated CuO disks using different lasersBabikr, Faten Abdelrhim MohammedSupervisor, -Nafie Abd Allattif Almuslethttps://repository.sustech.edu/handle/123456789/206712018-04-12T05:40:41Z2017-12-05T00:00:00ZDetermination of the optical properties of fabricated CuO disks using different lasers
Babikr, Faten Abdelrhim Mohammed; Supervisor, -Nafie Abd Allattif Almuslet
In this work, copper oxide (CuO) disks were prepared using a classical pressing machine, after mixing with potassium bromide. The disks were fabricated with different thicknesses (1.7, 2.59, 3.46, 4.29, 5.49, 5.92) mm.
The optical properties of CuO disk were studied using different types of monochromatic light sources in the wavelength range (300-950) nm.
The incident light intensities were measured in the absence of samples, which regarded as the reference ( ), then the transmitted intensity ( ) for each sample was measured by placing the monochromatic light source, the detector, and the sample on the same line. The reflected intensities ( ) also were measured by placing the monochromatic light source and the detector at angle of 450 with the samples. The absorption coefficient for each sample was calculated using Beer-Lambert law. In addition, the refractive index for each disk also was calculated.
The optical properties (absorption coefficient, transmission percentage, and refractive index) of the fabricated disks, with different thicknesses, were plotted as a function of wavelengths of the light sources .
The obtained results showed the possibility of using the CuO disks as an optical filters in certain wavelengths or as reflectors for other wavelengths
Thesis
2017-12-05T00:00:00Z