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Search Results: 1 - 10 of 654149 matches for " J. A.; "
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Effect of Annealing Temperature on Structural, Optical and Electrical Properties of Pure CdS Thin Films Deposited by Spray Pyrolysis Technique  [PDF]
A. Hasnat, J. Podder
Advances in Materials Physics and Chemistry (AMPC) , 2012, DOI: 10.4236/ampc.2012.24034
Abstract:

Effect of annealing temperature on the properties of CdS thin films are carried out in this work. Nanocrystalline cadmium sulphide (CdS) thin films were prepared using spray pyrolysis deposition (SPD) technique and the structural, optical and electrical properties were investigated for different annealing temperature (as deposited, 300, 400 & 500 C). The surface morphology and compositional properties studied by SEM and EDX respectively. The crystal structure of CdS thin film was studied by X-ray diffraction. The crystallite size and lattice constant of SPD CdS thin films were investigated. The optical parameters such as transmittance, absorption coefficient and energy band gap of the films with thermal annealing temperature was investigated by UV/VIS spectrophotometer. The variation of band gap values of CdS thin film samples were found to be in the range of 2.51 to 2.8 eV. Electrical resistivity measurements were carried out in fourprobe Vander Pauw method at different temperature. So CdS films may be a good candidate for suitable application in various optoelectronic devices.

The 1964 Wellington Study of Beatlemania Revisited  [PDF]
A. J. W. Taylor
Psychology (PSYCH) , 2014, DOI: 10.4236/psych.2014.515190
Abstract: In June 1964, an Honours class in clinical psychology set out to objectify the major parameters of crowd and audience reaction to the Beatles’ during the group’s three-day visit to Wellington, New Zealand. Advance publicity had warned of the “mass-hysteria” to be expected at the sight, sound and lyrics of the four lads from Liverpool. Adolescents anticipated their arrival eagerly, while the authorities were disparaging and somewhat fearful of the breakdown in law and order that might occur. The findings were published in Britain in 1966, taken a little further in the United States in1968, and the original published once more in Britain in 1992 by special request to encourage more psychologists to undertake research off campus. When writers from those countries mentioned the study recently near the 50th anniversary of the Beatles’ visit, it seemed interesting to review the accretion of similar studies that might have occurred. Sadly, the outcome showed that psychologists had not taken mass-audience research any further. Hence it was thought appropriate to lift the Wellington study from obscurity, in the hope of inspiring the next generation to make amends.
Preparation and Structural Characterization of Vanadium Doped Ni – B Binary Hard Alloys  [PDF]
J. A. Ajao
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2010, DOI: 10.4236/jmmce.2010.96040
Abstract: The microstructure of a series of binary Ni-B alloys containing various amounts of vanadium additions were investigated by Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Analysis (EDXA). Due to the vanadium addition in the alloys quenched from the liquidus, the formation of the Ni3B phase was enhanced even when the nominal composition was hypoeutectic. The addition of vanadium led to the formation of t (Ni20.4V2.6B6) phase during the present investigation. In addition, the crystallographic orientation relationship of this ternary phase with the nickel matrix was reported. The solid-state eutectoid transformation of the Ni3B phase during cooling was also reported and discussed.
Effect of Solidification Process Parameters on the Microstructure of Some Meltspun Nickel-Based Hardfacing Alloys  [PDF]
J. A. Ajao
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2009, DOI: 10.4236/jmmce.2009.810067
Abstract: The influence of solidification parameters on the morphology of a number of meltspun Nickelbased hard alloys has been investigated by means of scanning electron microscopy (SEM), conventional transmission electron microscopy and energy dispersive X-ray analysis (EDXA). It was established that the wheel velocity played a prominent role in the types of microstructure observed. Very high wheel velocity could lead to the formation of amorphous structure as observed in some of the alloys investigated. No appreciable effect of the ribbon thickness was observed on the microhardness of the alloys. It was also reported that the thermal transfer mode between the ideal and newtonian coolings was observed in all the alloys investigated.
Scanning Electron Microscopy of Some Slowly Cooled Nickel-Based Hardfacing Alloys Containing Iron Additions  [PDF]
J. A. Ajao
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2010, DOI: 10.4236/jmmce.2010.92012
Abstract: The service lifespan of components used at higher temperatures in corrosive and abrasive environments can be prolonged by high-temperature corrosion-resistant coatings. This study is concerned with the microstructural characterization of some slowly cooled Nickel–based hardfacing alloys investigated by differential thermal analysis (DTA), energy dispersive X – ray analysis (EDXA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The alloys were prepared in high frequency induction furnace under controlled atmosphere. Three major primary hard phases (Ni (α), M7C3, and the π phase) were identified during slow cooling in DTA depending on the nominal compositions of the alloys. Large undercoolings as well as intense solid state precipitations were observed in alloys with iron additions. The precipitations formed the basis of the high hardness values and strength of the alloys. It was also reported that the hardness values of the alloys increased as the iron contents increased.
Soil Salinity and Alkalinity Map Preparation Based on Spatial Analysis of GIS (Case Study: Tabriz Plain)  [PDF]
A. Farajnia, J. Yarahmadi
Open Journal of Geology (OJG) , 2017, DOI: 10.4236/ojg.2017.76052
Abstract:

Better management of agricultural fields is related to valuable information which can derived from soil salinity and alkalinity maps. These maps are considered as one of the most important factors which restrict plant growth as well as decline crops yield. The objective of this research was preparing of soil salinity and alkalinity maps in Tabriz plain over 50,000 hectares based on different techniques of spatial analysis in GIS software. For this mean, study area was divided in 1500 × 1500 m2 grid cells. Then, geographical coordinate of each grid recorded in UTM system. So, they were transferred into GPS for navigating to the exact excavation location. After soil sampling and transferring to the lab, their EC and PH were measured in saturation extract of soil samples. So, spatial distribution of soil sampling points was prepared in form of point map by GIS software. Generalization of point information to surface was performed using different interpolation algorithms and based on standards of Soil and Water Research Institute. Accuracy of interpolated maps was evaluated due to the MAE and MBE values. The results showed that the lowest observed error is related to the Spline method and therefore, this method was used for spatial modeling of salinity and alkalinity maps in the intended area. The research findings demonstrated that from total of 50,000 hectares, only 3066 hectares were without salinity and alkalinity limitation (6.1%), 9066 hectares had low salinity and alkalinity (18.1%); 17,772 hectares had average limitation for salinity and alkalinity (35.6%) and the remaining 20,096 hectares had high and very high limitation for salinity and alkalinity.

Hydrogeology of the Basin Granitoids in the Sekyere South District of Ashanti Region, Ghana  [PDF]
A. Ewusi, J. Seidu
Journal of Geoscience and Environment Protection (GEP) , 2018, DOI: 10.4236/gep.2018.64015
Abstract: The hydrogeology of the Basin Granitoids in the Sekyere South District of Ashanti Region of Ghana has been evaluated applying the electrical resistivity imaging (ERI) geophysical technique and pumping test analysis. The ERI was conducted to obtain information on resistivity distribution for groundwater accumulation and pumping test was used to obtain transmissivity and sustainable yields of boreholes. Results from the ERI technique show that the general resistivity distribution in the area is between (20 - 4000) Ω-m and the resistivity range that is related to groundwater occurrence is between (50 - 300) Ω-m for the weathered and (100 - 600) Ω-m for the fractured granitic rocks. The aquifers are generally shallow to medium depth and where resistivities of the aquifer zones are less than 400 Ω-m in the fresh granites, high yields are likely to be attained. Pumping test also revealed that transmissivity values range between (5.89 - 43) m2/day, with sustainable yields ranging between 50 - 380 m3/day. These results suggest that boreholes in the area will be sustainable for domestic supplies.
The Harmonic Oscillator with Random Damping in Non-Markovian Thermal Bath  [PDF]
N. J. Hassan, A. Pourdarvish, J. Sadeghi
World Journal of Mechanics (WJM) , 2016, DOI: 10.4236/wjm.2016.68019
Abstract: In this paper, we define the harmonic oscillator with random damping in non-Markovian thermal bath. This model represents new version of the random oscillators. In this side, we derive the overdamped harmonic oscillator with multiplicative colored noise and translate it into the additive colored noise by changing the variables. The overdamped harmonic oscillator is stochastic differential equation driving by colored noise. We derive the change in the total entropy production (CTEP) of the model and calculate the mean and variance. We show the fluctuation theorem (FT) which is invalid at any order in the time correlation. The problem of the deriving of the CTEP is studied in two different examples of the harmonic potential. Finally, we give the conclusion and plan for future works.
Electrochemical Separation of Metal Silver from Industrial Wastewater  [PDF]
M. A. Olutoye, J. A. Alhamdu
Advances in Chemical Engineering and Science (ACES) , 2014, DOI: 10.4236/aces.2014.44043
Abstract: Investigation into the separation of metal silver from industrial wastewater using electrochemical cell was carried out. Wastewater from photo laboratories was collected and treated batch wise using electrolytic equipment. A constant voltage of 2.0 V and variable current in the range of 0.3 - 0.6 A at normal temperature were passed through the electrolyte for a period from 0.25 - 1.0 h. The results showed that increase in current yield an increase in the amount of metallic silver recovered with highest values of 2.3 g and 2.8 g at 0.6 A for the tested samples 1 and 2, respectively. The electrochemical separation method proved to be more reliable and economical when compared to other methods and also, reduction in environmental pollution of industrial wastewater containing high concentration of silver metal is achieved.
Study of the Effect of Cu2+ in the Lattice Dynamics of Doped Magnetites Obtained by the Hydrothermal Synthesis Method  [PDF]
A. A. Velásquez, J. P. Urquijo
Spectral Analysis Review (SAR) , 2013, DOI: 10.4236/sar.2013.12002
Abstract: In this work, the effect of Cu2+ on the structural and magnetic properties of samples of magnetite is addressed. Samples
of magnetite, both pure and Cu2+ doped, Fe3-xCuxO4, with x = 0, 5, 10 and 20 atm.% were synthesized hydrothermally. The two-lattice method was employed to measure the Mossbauer recoilless fraction of magnetite relative to hematite (fmag/fhem)
of the samples, looking for evidence of substitution of Fe2+ by Cu2+. The relative recoilless fraction measurements were performed by taking room temperature Mossbauer spectra of mixtures of each sample with analytical grade hematite. The Mossbauer measurements were complemented with Atomic Absorption Spectroscopy (AAS) and Energy Dispersive X-ray Spectroscopy (EDS). The analyses by AAS and EDS showed that the copper concentration in the final products
increases with increasing the content of Cu2+ in the starting solutions. The Mossbauer analyses showed a linear decrease trend of the relative Mossbauer recoilless fraction with increasing concentration of Cu2+in the samples, as well as a reduction in the hyperfine magnetic field, which was more significant in the octahedral sites than tetrahedral sites. The broadening of the Mossbauer spectral lines was more significant for the octahedral sub spectrum than for the tetrahedral sub spectrum. Our study points that Cu2+ occupies preferentially the octahedral sites, where it substitutes Fe2+ species, generating broadening in the lines of the octahedral sub spectrum and a reduction in the probability of having nuclear resonant absorption of Mossbauer gamma rays in the samples.

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