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245 results on '"Moses, Elisha"'

53. Enhanced 355 nm Lasers Obtained from BBO and KDP by Sum Frequency Mixing

Author

Abd. Rahman Tamuri, Moses Elisha Kundwal, and Mohd Nizam Lani

Subjects
Optical frequency multiplier, Materials science, business.industry, Far-infrared laser, Potassium titanyl phosphate, Nonlinear optics, Laser, Barium borate, Atomic and Molecular Physics, and Optics, law.invention, chemistry.chemical_compound, Optics, chemistry, law, High harmonic generation, Optoelectronics, business, Engineering (miscellaneous), Lasing threshold
Abstract

A key challenge to researchers in optics and photonics is the lack of suitable broadband lasing materials for the ultraviolet (UV) domain. Hence, the use of nonlinear optics for generation of harmonics for the UV domain, from either infrared (IR) or visible (Vis) lasers. In this work, we made use of nonlinear optical conversion to develop a compact 355 nm pulsed UV laser from a passive Q-switched pulsed infrared laser (1,064 nm). Two nonlinear crystals, barium borate (BBO) and potassium dihydrogen phosphate (KDP), are, in turn, used to generate the third harmonic of the IR laser by frequency mixing, after initial frequency doubling through a potassium titanyl phosphate (KTP) crystal. We make the laser user friendly by constructing crystal holders for the nonlinear crystals so that it becomes easier to angle tune the crystals for optimum generation of the third harmonic. The UV laser is stable and has output pulse energy up to 148 and 110 mJ, with conversion ratio from IR to UV of about 0.29 and 0.21 for BBO and KDP, respectively.

Published
2015

54. Altered Brain Network Dynamics in Schizophrenia: A Cognitive Electroencephalography Study

Author

Naim-Feil, Jodie, Rubinson, Mica, Freche, Dominik, Grinshpoon, Alexander, Peled, Abraham, Moses, Elisha, and Levit-Binnun, Nava

Abstract

Alterations in the dynamic coordination of widespread brain networks are proposed to underlie cognitive symptoms of schizophrenia. However, there is limited understanding of the temporal evolution of these networks and how they relate to cognitive impairment. The current study was designed to explore dynamic patterns of network connectivity underlying cognitive features of schizophrenia.

Published
2024
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56. COMPARISON OF HEAT TRANSFER PROPERTIES OF DRY SAND AND MAGNESIUM OXIDE POWDER BY SINGLE-PROBE METHOD

Author

Osita Chukwudi Meludu, Markus Ndenah Linah, and Moses Elisha Kundwal

Subjects
Materials science, Fabrication, Heating element, Magnesium, General Engineering, Mineralogy, chemistry.chemical_element, Atmospheric temperature range, Thermal conductivity, Heat flux, chemistry, Heat transfer, Thermal, Composite material
Abstract

The use of magnesium oxide (MgO) powder in electrical heating appliances is based on its thermal and electrical insulating properties. However, dry sand, which is readily available and free on the surface horizon than MgO powder also possesses good thermal and electrical insulating properties that could be utilized in the fabrication of electrical heating devices. In this study, we determined and compared heat transfer properties of dry fine-medium sand (0.125-0.50 mm) and dry coarse sand (0.50-1.00 mm) with those of MgO powder, using the single-probe method. Electrical heating equipment was designed and fabricated with a heating element that generated a heat flux of 18.05Wm -1 . From the results obtained, the thermal conductivities of dry fine-medium sand, dry coarse sand and MgO powder were found to be 0.21 m -1 K -1 , 0.22 Wm -1 K -1 and 0.36 Wm -1 K -1 respectively. Temperature increase per second were also obtained and found to be 4.75 × 10 -2 Ks -1 in dry fine-medium sand, 4.28 × 10 -2 Ks -1 in dry coarse sand and 2.03 × 10 -2 Ks -1 in MgO powder. Thus, while it took MgO powder 472 s to warm from 30 o C to 40 o C, it took dry coarse sand and dry fine-medium sand only 229 s and 205 s respectively to warm through the same temperature range.

Published
2015

57. MICROBIAL INACTIVATION USING PULSED LIGHT- A REVIEW

Author

Moses Elisha Kundwal, Abd. Rahman Tamuri, and Mohd Nizam Lani

Subjects
Future study, Chemistry, business.industry, law, General Engineering, Pulse frequency, Optoelectronics, Pulsed power, business, Laser, Pulse light, Microbial inactivation, law.invention
Abstract

The use of pulse light to inactivate microbes has recently attracted interest of many researchers. Consequently, there are various reports on the efficacy and advantages of pulsed light in microbial inactivation; and also the potentiality of pulsed light systems being adopted for industrial use in this regards. Here, we review some of the works done in relation to microbial inactivation with pulse light, with emphasis on the role played by pulse light parameters such as fluence, spectral range, pulse power, pulse width, pulse frequency, etc. We focussed in particular on factors that make pulsed light systems more effective than their continuous wave counterpart and also proffer suggestions on possible areas for improvement in future study. The use of pulsed lasers in inactivating microbes was briefly appraised. Also, prospects and challenges in the use of pulsed light for inactivation were highlighted.

Published
2015

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