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Articles 91 - 116 of 116
Full-Text Articles in Physics
Establishment Of Background Radiation Dose Rate In The Vicinity Of The Proposed Manyoni Uranium Project, Singida, Joyce Elisadiki, Ismael Makundi
Establishment Of Background Radiation Dose Rate In The Vicinity Of The Proposed Manyoni Uranium Project, Singida, Joyce Elisadiki, Ismael Makundi
Tanzania Journal of Science
The absorbed dose rate in air in the vicinity of the proposed Manyoni uranium mining project located in Singida region, Tanzania, was determined so as to establish the baseline data for background radiation dose rate data prior to commencement of uranium mining activities. Twenty stations in seven villages were selected and monitored for six months from June 2012 to November 2012. The absorbed dose rate in air was measured by means of CaF2:Dythermoluminescent dosimeters (TLD-200). The annual effective dose was estimated using outdoor occupancy factor of 0.2 and conversion coefficient factor of 0.7 SvG y-1. The mean dose rate was …
Effects Of Target Composition On The Optical Constants Of Dc Sputtered Zno:Al Thin Films, B. Samwel, M. E. Samiji, N.R. Mlyuka
Effects Of Target Composition On The Optical Constants Of Dc Sputtered Zno:Al Thin Films, B. Samwel, M. E. Samiji, N.R. Mlyuka
Tanzania Journal of Science
Al-doped ZnO thin films were deposited from ZnO:Al ceramic and Zn:Al metal alloy targets in Ar and Ar + O2 atmospheres respectively, using Direct Current (DC) magnetron sputtering. The samples exhibited transmittance T > 80% in visible region with good NIR shielding. The results indicated that, band gap energy ranged from 3.34 to 3.44 eV and 3.39 to 3.46 eV for films prepared from alloy and ceramic targets, respectively. Films obtained from alloy target at a substrate temperature of 200 oC showed low electrical sheet resistance of 10 Ω/sq, and highest values of mobility (15.9 cm2/Vs) and carrier concentration (2.98 × …
Luminous Transmittance And Phase Transition Temperature Of Vo2:Ce Thin Films Prepared By Dc Reactive Magnetron Sputtering, S Ambonisye, M E Samiji, N R Mlyuka
Luminous Transmittance And Phase Transition Temperature Of Vo2:Ce Thin Films Prepared By Dc Reactive Magnetron Sputtering, S Ambonisye, M E Samiji, N R Mlyuka
Tanzania Journal of Science
Vanadium dioxide (VO2) and cerium-doped vanadium dioxide (VO2:Ce) thin films were prepared by DC reactive magnetron sputtering from vanadium metallic target and V-Ce alloy targets. Luminous transmittance and phase transition temperatures of the films were studied. The Shimadzu SOLIDSPEC-3700 DUV-VIS-NIR spectrophotometer was used to measure the transmittance and reflectance of the films. The phase transition temperature (τc) of the films was obtained from both the transmittance and sheet resistance against temperature curves. A change in sheet resistance of 2 to 3 orders of magnitude was observed for both undoped and Ce-doped VO2 films. Comparison between undoped and doped VO2 films …
Uvarisesquiterpene D: A New Benzopyranyl Sesquiterpene Isolated From Uvaria Lucida Ssp. Lucida, Qa Mgani
Uvarisesquiterpene D: A New Benzopyranyl Sesquiterpene Isolated From Uvaria Lucida Ssp. Lucida, Qa Mgani
Tanzania Journal of Science
Hitherto unreported benzopyranyl sesquiterpene, uvarisesquiterpene D, has been isolated from the stem bark of Uvaria lucida ssp lucida. Its structure had been elucidated by spectroscopic analysis (IR, MS and NMR) and comparison of its spectral data with the known related compounds uvarisesquiterpene B and selin-11(12)-4α-ol. The latter compound was co-isolated with the new natural product as well as caryophyline oxide and lucidine.
Probing The Cob(Ii)Alamin Cond Uctorhhypothesis With Glutamate Mutase From Clostridium Cochlearium, Fe Lyatuu, A Parthasarathy, K Zhou, K Zelenka, Fh Zelder, W Buckel
Probing The Cob(Ii)Alamin Cond Uctorhhypothesis With Glutamate Mutase From Clostridium Cochlearium, Fe Lyatuu, A Parthasarathy, K Zhou, K Zelenka, Fh Zelder, W Buckel
Tanzania Journal of Science
It had been proposed that during reversible coenzyme B12 dependent rearrangements, cob(II)alamin is not merely present as a spectator but also acts as a conductor by stabilizing the methylene radical intermediates. Density functional theory (DFT) calculations suggested a hydrogen bond between C19-H of the corrin ring and the 3'-OH moiety (O3RL) of the 5'- deoxyadenosyl radical resulting in a decrease of the activation energy by about 30 kJ mol-1. We tested this hypothesis with glutamate mutase and artificial coenzyme B12 derivatives. The assembly of coenzyme B12 (adenosylcobalamin) with recombinant components GlmS and GlmE of glutamate mutase from Clostridium cochlearium reconstitutes …
Electrical Properties Of Dc Reactive Magnetron Sputtered Zno:Al Films From Optical Spectra, Pd Nsimama, Me Samiji
Electrical Properties Of Dc Reactive Magnetron Sputtered Zno:Al Films From Optical Spectra, Pd Nsimama, Me Samiji
Tanzania Journal of Science
Reactive direct current (DC) sputtered ZnO:Al films were prepared using the plasma emission monitoring (PEM) system. Films were deposited using PEM setpoints ranging from 50 to 80%. Transmittance and reflectance of the films were measured by using the UV-VIS-NIR Lambda 900 double beam spectrophotometer. The sheet resistance was measured using the four-point probe. Films optical spectra were fitted with the Drude model to determine their charge carrier concentration, mobility and the alternating current (AC) resistivity. The highest values of mobility and charge carrier concentration were 8.31cm2/Vs and 2.14 x 1021cm-3 respectively. The lowest value of the AC resistivity was given …
Correlation Between Morphological, Optical And Electrical Properties Of Zno:Al/Zno Double Layers And The Cu(In,Ga)Se2 Solar Cell Efficiencies, Pd Nsimama
Tanzania Journal of Science
The morphological, optical and electrical properties of magnetron sputtered ZnO:Al/ZnO double layers are reported and their correlations with their respective Cu(In,Ga)Se2 (CIGS) solar cell efficiencies are presented. The ZnO:Al/ZnO double layers were produced by using the established baseline RF process and plasma emission monitoring (PEM) DC reactive sputtering. The scanning electron microscope (SEM) and atomic force microscope (AFM) were employed for the surface morphological measurements. The charge carrier concentrations, mobilities and AC resistivities were deduced from Drude’s model. The DC resistivities were determined from the four-point probe measurements. Transmittance and reflectance measurements were done by using the UV-VIS-NIR Lambda 900 …
Spectral Analysis Of Ground Magnetic Data In Magadi Area, Southern Kenya Rift, Jg Githiri, Jp Patel, Jo Barongo, Pk Karanja
Spectral Analysis Of Ground Magnetic Data In Magadi Area, Southern Kenya Rift, Jg Githiri, Jp Patel, Jo Barongo, Pk Karanja
Tanzania Journal of Science
The area surrounding Lake Magadi in the southern Kenya rift is characterized by hot springs that issue from fractures distributed along the shores of the lake. Presence of earthquake swarms that cluster in northern margin of Lake Magadi strongly indicate magmatic activity in the area. This study was done as a follow-up to investigate depth to the heat source possibly causing high seismic activity and high heat flow in the area. A ground magnetic survey was conducted to investigate geothermal potential of the area and a magnetic anomaly contour map prepared. Spectral analysis involving determining power spectrum was applied to …
Identification Of Clay Minerals Of The Eastern Southern Region Of Lake Victoria By Ethylene Glycol And Heat: X-Ray Diffraction And Infrared Spectroscopy Studies, E. H. J. Lugwisha
Identification Of Clay Minerals Of The Eastern Southern Region Of Lake Victoria By Ethylene Glycol And Heat: X-Ray Diffraction And Infrared Spectroscopy Studies, E. H. J. Lugwisha
Tanzania Journal of Science
The effect of glycol and heat on some clay minerals of the eastern southern region of Lake Victoria in Tanzania has been studied. First, Whole Rock Powder mount XRD analysis was carried out at the measuring range 2 # ranging between 2o – 65o. Four non-clay minerals found in samples were Na-feldspar, K-feldspar, pyrope and quartz. Oriented clay mineral XRD analysis diffractograms were developed when the air-dried samples were diffracted in measuring range 2# between 2oo – 32o. Main clay mineral groups found in the samples were kaolinite, illite and montmorillonite. After glycolating the samples, it was evident that kaolinite …
Implementation Of A Tabu Search Heuristic For The Examinations Timetabling Problem, A. R. Mushi
Implementation Of A Tabu Search Heuristic For The Examinations Timetabling Problem, A. R. Mushi
Tanzania Journal of Science
This paper reports on the design and implementation of an algorithm for the construction of an examinations timetable. The Examinations Timetabling Problem is the problem of assigning examinations and candidates to time periods and examination rooms while satisfying a set of specific constraints. Every University has a different set of constraints and structure of examinations. Generally, timetabling problems are NP-Hard and therefore very difficult to solve. However, they are of great interest due to their important practical application in educational institutions. This paper discusses a heuristic algorithm basing on the examinations timetabling at the University of Dar es salaam. The …
A Teaching Intervention To Increase Achievement Of Hispanic Nonscience Majors Taking Physical Science Courses, G. Herold Poelzer, Liang Zeng
A Teaching Intervention To Increase Achievement Of Hispanic Nonscience Majors Taking Physical Science Courses, G. Herold Poelzer, Liang Zeng
Physics & Astronomy Faculty Publications
This quasi-experimental pilot study of nonscience majors taking a physical science course at a university in South Texas was conducted on Hispanic undergraduate students, and is theory based--an application of attribution theory. That the treatment group outperformed the comparison group provides evidence of the positive effect of having students reflect on controllable reasons for their grades and on their subsequent planning of strategies to maintain or improve those grades. (Contains 1 table and 2 figures.)
Correlation Between Sunshine Hours And Climatic Parameters At Four Locations In Uganda, K. Karume, E. J. K. B Banda, J Mubiru, M Majaliwa
Correlation Between Sunshine Hours And Climatic Parameters At Four Locations In Uganda, K. Karume, E. J. K. B Banda, J Mubiru, M Majaliwa
Tanzania Journal of Science
One of the most important factors in solar energy production is related to the predictability of sunshine hours. The objective of this study is to assess the correlation between sunshine hours and relative humidity, cloud cover, maximum and minimum temperature, for the purpose of identifying the most appropriate parameter(s) for the prediction of sunshine hours in Uganda. Climatic data for the meteorological stations of Entebbe, Mbarara, Tororo and Makerere, extending over a period of 15 years (1990-2005) was collected from the Department of Meteorology, Kampala. The data set included maximum temperature, minimum temperature, relative humidity at 6 am and at …
Thermal And X-Ray Investigations Of Kowak Clay In Northwestern Tanzania And Its Possible Industrial Use, E. H. J. Lugwisha
Thermal And X-Ray Investigations Of Kowak Clay In Northwestern Tanzania And Its Possible Industrial Use, E. H. J. Lugwisha
Tanzania Journal of Science
A study of some properties of clays collected from selected sites in Kowak deposit in Tarime District was carried out in order to assess their suitability as raw materials in ceramic and its related industries. The silica (SiO2) content in the clays is predominant, and is about 66.89% followed by alumina (Al2O3) that is 20.2%. Haematite (Fe2O3) was found to be the third in abundance with an average of 3.58%. Other constituents are present in small proportions. Water loss at 105 oC lies between 2.70% and 2.76%. DTG, TG, XRD techniques and chemical analyses studied by AAS method were used …
Coastal Tanzania, A New Home To The Living Coelacanth: An Oceanographic Analysis, N. Nyandwi
Coastal Tanzania, A New Home To The Living Coelacanth: An Oceanographic Analysis, N. Nyandwi
Tanzania Journal of Science
Coelacanth is no longer a new fish in Tanzania. After it was first discovered in September 2003 off Kilwa Masoko in southern Tanzania and with awareness campaigns, fishermen have reported further landings since, mostly in Tanga, northern Tanzania at Kigombe village. Analysis of habitat conditions suitable for the coelacanth indicates that the oceanography may just be right for the fish to have a permanent residence as opposed to the theory of drifters from a natural home elsewhere. At one time three specimens were captured together in the same net indicating that they formed a group. Oceanographic studies of the habitat …
Performance Analysis Of Cdma-Based Wireless Communication Systems Using The Simplified Improved Gaussian Approximation Method, H N Kundaeli
Performance Analysis Of Cdma-Based Wireless Communication Systems Using The Simplified Improved Gaussian Approximation Method, H N Kundaeli
Tanzania Journal of Science
The limitations initially prevalent in CDMA-based systems have been gradually solved thereby making CDMA a very promising access mode for future communication systems. Following the move towards higher data transmission rates, however, a number of other problems have emerged that need to be tackled. As a result, current world-wide research on CDMA-based systems is geared towards high speed, highly mobile multimedia communication applications. In this paper, the performance of a multi-user DS-CDMA communication system operating in a Rayleigh fading environment is investigated. Performance expressions are derived and the variation of the performance with various system parameters is presented.
Bajocian Ammonites From Msata Hill (Lugoba Formation) In The Hinterland Of Dar Es Salaam, Tanzania, S Kapilima
Bajocian Ammonites From Msata Hill (Lugoba Formation) In The Hinterland Of Dar Es Salaam, Tanzania, S Kapilima
Tanzania Journal of Science
Ammonites from the Middle Jurassic exposures of the Lugoba Formation at Msata, are described for the first time in Tanzania. Out of a number of ammonite fragments recovered from the bluish-green silty limestone (M3), only three fragments were fairly well preserved to permit their specific identification. Two species were identified: Dorsetensia cf. D. romani (OPPEL) and Oecotraustes (Paroecotraustes?) cf. angustus DOUVILLE. This ammonite assemblage is biostratigraphically correlatable with the Lower Bajocian Posidonia shale of the Kambe Limestone series in Kenya, in which similar ammonites species and other related Bajocian species have been described. Pending new discovery of ammonoid fauna and …
Trace Elements Characterization Of The Hydrothermally Deposited Tanzanite And Green Grossular In The Merelani – Lelatema Shear Zone, Northeastern Tanzania, Epj Malisa
Tanzania Journal of Science
Geochemical investigations of trace element contents of different rock samples were determined in the late Proterozoic metamorphic sequences of the Mozambique Belt along the Merelani–Lelatema shear zone, northeastern Tanzania. The area is composed of the following rock types: pelitic and semi-pelitic gneisses, psammitic, hydrothermally altered including carbonate-rich, carbonate-gypsum-rich, and iron-rich rocks, pegmatite dykes and crystalline limestones. Trace element characteristics of the principal rock units in and outside the shear zone have been compiled and studied. With the exception of higher barium contents in pelites, trace element contents in the psammitic and pelitic gneisses show some similarities while in the hydrothermally …
Mobility And Immobility Of Mid-Ocean Ridges And Their Implications To Mantle Dynamics, Me Kamwaya
Mobility And Immobility Of Mid-Ocean Ridges And Their Implications To Mantle Dynamics, Me Kamwaya
Tanzania Journal of Science
In the past two decades, the mobility of mid-ocean ridges relative to the mantle (absolute migration) have been correlated with major observable features, such as, spreading asymmetry and asymmetry in the abundance of seamounts. The mobility of mid-ocean ridges is also thought to be an important factor that influences the diversity of ridge-crest basalts. However, the mobility of mid-ocean ridges have not yet been defined and mapped. The absolute migration of global mid-ocean ridges since 85 Ma has been computed and mapped. Global mid-ocean ridges have migrated extensively at varying velocities during that period. Presently, the fast-migrating ridges are the …
Comparison Of Direct Return And Birth-Death Return Receivers, H N Kundaeli
Comparison Of Direct Return And Birth-Death Return Receivers, H N Kundaeli
Tanzania Journal of Science
The performance of frame synchronized communication systems is governed largely by the design chosen for the receiver. Some systems employ a structure in which the receiver returns directly to the sync phase when a valid marker is encountered while in the loss verify state. These have been greatly studied. In some systems, the return path in the loss verify phase is implemented as a birth-death process. These systems have not received much attention. In this report, a receiver which employs a birth-death like structure in the loss path is investigated. Expressions for the performance parameters are derived and compared with …
The Geochemistry Of Banded Iron Formations In The Sukumaland Greenstone Belt Of Geita, Northern Tanzania: Evidence For Mixing Of Hydrothermal And Clastic Sources Of The Chemical Elements, M A H Maboko
Tanzania Journal of Science
Major and trace element compositions of samples of Banded Iron Formations (BIF) from the Neoarchaean Sukumaland Greenstone Belt of Geita in northern Tanzania reveal that the BIF precipitated from hydrothermal solutions. Fe-Ti-Al-Mn systematics suggest that the hydrothermal deposits have been contaminated, by up to 20% by weight, with detrital material having a composition similar to modern deep-sea pelagic clays. SiO2 and Fe2O3 contents are 48.2 to 88.5% and 8.9 to 49.1% respectively. Al2O3 contents lie between 0.33 and 2.1% and show no correlation with either Fe2O3 or SiO2. Al2O3 is, however, positively correlated with Ti, Ga, Hf, Rb,Th, Zr and …
Thermogravimetric Study Of Gadolinium Chlorotungstate In Air Between 25 And 1500°C., F N Ngassapa, N U Venskovskii
Thermogravimetric Study Of Gadolinium Chlorotungstate In Air Between 25 And 1500°C., F N Ngassapa, N U Venskovskii
Tanzania Journal of Science
Using DTA, X-ray powder diffraction, chemical and optical methods, the thermostability of Gd3WO6Cl3 was investigated. The compound was relatively stable on heating in air up to 710oC. Above this temperature it exhibited two decomposition temperature ranges (710-900oC and 900-1130oC). The final product consisted of a mixture of gadolinium tungstate of different composition. This suggests the decomposition scheme of polyphase products
Influence Of Endocrine Activity On Larval Development In Busseola Fusca (Fuller) (Lepidoptera:Noctudine), M Njau
Tanzania Journal of Science
The present study investigated the role of juvenile and moulting hormones in development of Busseola fusca. Morphometric measurements were used to distinguish differences in endocrine activity between non-diapause and diapause development with regard to the prothoracic glands and the corpora allata. The corpora allata of non-diapause larvae were similar in size to those of diapause larvae. The critical period for the prothoracic glands to produce the required titer of ecdysone for further development was by the third day after ecdysis to the last larval instar. Juvenile hormone extracts from haemolymph of Busseola fusca larvae in non-diapause and diapause development had …
Theoretical Evaluation Of Selective Radiation–Absorbing Surface, K.R. O’Shea
Theoretical Evaluation Of Selective Radiation–Absorbing Surface, K.R. O’Shea
Tanzania Journal of Science
An algol computer program is described, by means of which the spectral reflectivity for any angle of incidence may be calculated for a surface consisting of up to two thin absorbing films on a bulk substrate. The values of optical constant, n and k, for the materials used and also the thickness of the films, are the only data required. Calculated reflectivities have been shown to be consistent with experimental results.
On The Field-Induced Infra-Red Absorption Of Gaas, Frederick Ngawo Onyango
On The Field-Induced Infra-Red Absorption Of Gaas, Frederick Ngawo Onyango
Tanzania Journal of Science
A theoretical survey of electric field–induced effects on one-and two-phonon absorption of GaAs is presented. The eigen-values and hence eigen-vectors are calculated for an external field applied along [001] and dependence of electro–absorption on the direction of radiation polarization established.
Studies In Artificial Rain: Their Progress And Prospects, P. B. Vitta
Studies In Artificial Rain: Their Progress And Prospects, P. B. Vitta
Tanzania Journal of Science
The progress made by studies of the phenomenon of rain is reviewed. Several techniques for modifying clouds so as to accelerate rain-drop precipitation are described.
An Attempt To Control Boundary Layer Turbulence With Nonisotropic Compliant Walls, R. Grosskreutz
An Attempt To Control Boundary Layer Turbulence With Nonisotropic Compliant Walls, R. Grosskreutz
Tanzania Journal of Science
A review of turbulence production in boundary layers leads to a new approach to boundary layer control by means of nonisotropic compliant walls. Suitably constructed coatings were tested and demonstrate that the concept is basically valid.