IOSR-JAP   Volume-9 ~ Issue-3 ~ May-June 2017

ABSTRACT: This work reports Studies that were carried out to investigate the impact of harmattan sun and dust on the eye. These includes ocular media absorbance, ocular related disease incidence, Sun intensity and amount of atmospheric dust during harmattan and non harmattan periods in Jos Nigeria. This is because the eye is the essential organ of sight. It functions by way of refraction of light (from objects) by the refracting media (the cornea, aqueous and vitreous humours and the lens) onto the retina. The brain which is connected to the eye through the optic nerve does the interpretation. Vision loss/blindness could result if any these parts fails to function from damage.............

Keywords: Harmattan sun, Dust, Human eye

[1]. N. Minka, (2016). Effect of Cold-Dry (Harmattan) and Hot –Dry Seasons.
[2]. BN. Okeahialam, (2016).The cold Dusty Harmattan
[3]. R.R Burton,(2013). The harmattan over west Africa: nocturnal structure and frontogenesis.
[4]. A.M.Kundril,(2008). Constitute composition of harmattan dust and its influence on properties of fadama soils in semi arid.
[5]. OA. Ogunseitan, (2007). Harmattan Haze and Environmental Health.
[6]. Mcgrow-Hill: Encyclopedia of Science and Technology. (1971) vol.5 770 volume 3 Pg 32o

ABSTRACT: This study aims to investigate the effects of radiation dose on the TL of γ-Al2O3:C.The material was exposed to beta radiation using the Risø TL/OSL-DA-15 Reader equipped with a 90Sr/90Y beta irradiator. The luminescence signals were measured by initially heating the samples at a heating rate of 5oC/s from room temperature (RT) to 500oC following β-irradiation and the glow curves, dose response determined respectively. The sample, doped with 1.0g of carbon graphite showed clear TL peaks at 256, 254, 242, and 244oC at 0.5Gy, 1.0Gy, 5.0Gy and 10.0Gy respectively. Dose response curve analysis showed a linear response in the dose range from 0.5Gy to 10Gy. With the results obtained, it can be concluded that the TL of γ-Al2O3:C increases with increase in radiation dose and this indicates that this material is suitable for personnel dosimetric applications.

Keywords: γ-Al2O3:C, Thermo luminescence, radiation dose, heating rate, glow curves, personnel

[1]. C. Cosma,A.Timar, V. Bene, I. Pop, T. Jurcut, Ciorba, D. Using Natural Luminescent Materials and Highly Sensitive Sintered Dosimeters MCP-N(LiF:Mg,Cu,P) in Radiation Dosimeter. Journ. Optoelect. Advanc. Materials,10 (3), 2008, No. 3, 573-577.
[2]. E. J. Hall, and D. J. Brenner, Cancer Risks from Diagnostic Radiology. The British Journal of Radiology, 2008, 81,362-378
[3]. M. C.Aznar, Real-time In vivo Luminescence Dosimetry in Radiotherapy and Mammography using Al2O3:C. Published Ph. D. Thesis, Riso National Laboratory, Roskilde, Denmark.2005.
[4]. M. S. Akselrod, and V. S. Kortov, (1990). Thermoluminescent and Exoemission Properties of New High Sensitivity TLD α-Al2O3:C Crystals. Radiat. Prot. Dosim. 66, 105-110.
[5]. F. D.G.Rocha, and L. V.E.Caldas, Characterization of Al2O3 Sintered Pellets for Dosimetric Applications in Radiotherapy. Journ. Radiol. Prot. 19(1), 1999, pp51-55 UK.

ABSTRACT: Thermal noise is one of the most important challenges in analogue intergrated circuits design. This problem is more critical in switched capacitor (Sc) filters due to the aliasing effect of wide band thermal noise. In these circuits, switching introduces a boost in the power spectral density of the thermal noise due to aliasing. Unfortunately, even though the theory of noise in Sc circuits is discussed in the literature, it is very tedious and requires highly sophisticated and not widely available software. The purpose of this paper is twofold. It provides a tutorial description of the physical phenomena taking place in anSc circuit while it processes noise............

[1]. D.A. Johns and K. Martin, Analog integrated circuit Design. New York, Wiley, 1997.
[2]. C. Enz and G.C. Temes, "Circuit techniques for reducing the effects of op-amp imperfections. Autozeroing, Correlated double
sampling, and chopper stalization," Proc. IEEE, vol. 84, No. 11, PP. 1584-1614, Nov. 1996.
[3]. R. Gregorian and G.C.Temes, Analog MOS Integrated Circuits for signal processing. New York. Wiley, 1986, Sec 7.4
[4]. R. Schreier and G.C Temes, Understanding Delta Sigma Data Converters, Piscataway, NJ: JEEE Press/Wiley, 2005. Appendinc.
[5]. J. Stecusgard, "Noise sources in switched capacitor delta sigma modulators", in Lecture Notes for "Practical Approach to Delta
Sigma Design, Lansanne, Switzerland, Jan. 21-25, 2004 [online]

ABSTRACT: The study examines the variation of thermal properties of bulk and particle of three different wood species: Pterygotamacrocarpa, Miliciaexcelsa and Celtisphillipensisof the families of Sterculiaceae, Moraceae and Ulmaceae.The particle samples were moulded to appropriate disc shape using modified hydraulic press mould while the bulk samples were turn into disc shape using circular saw machine. The results showed that thermal conductivity of the selected wood materials changed with particle sizes.Bulk samples have higher thermal conductivity values than the particles for all the wood species.Among the particle sizes, 300 μm has the highest thermal conductivity value compared with 600 μm and 850 μm respectively................

Keywords: Wood materials, thermal conductivity, solar device, Lee's disc.

[1]. Ayugi, G., Banda, E. J. K. and D'Ujanga, F. M. (2011). Local Thermal Insulating Materials for Thermal Energy Storage
Department of Physics. .Makerere University, Kampala, Uganda, Rwanda Journal, 23:21-29.
[2]. Duncan, M. P. and Mark, J. (2000) Thermal Conductivity of PTFE and PTFE Composites' IPTME.Loughborough University,
Loughborough, UK. Pp. 580-581
[3]. Griffin, J. J. and George, J. (2002). Lees' Conductivity Apparatus (Electrical Method) LL44-590 S. 1122/7302, Griffin & George
Ltd., Wembley, Middlesex UK. Pp 2-4
[4]. Ken, F. (2014). Useful Tropical Plants. Database web interface
[5]. Oluyamo, S. S. and Adekoya, M. A. (2015). Effect of Dynamic Compression on Thermal Properties of Selected Wood Products of
Different Particle Sizes. International Research Journal of Pure and Applied Physics 3: 22-29.