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匹配条件: “ Williams W. Edobor” ,找到相关结果约89269条。
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Effectiveness of Gully Erosion Control Measures in Edo State, Nigeria  [PDF]
Augustine Osayande, Williams W. Edobor, Sako Kato
Open Access Library Journal (OALib Journal) , 2019, DOI: 10.4236/oalib.1105018
Abstract:
The study examined the effectiveness of Gully Erosion Control Measures in Edo State, Nigeria. The objectives are to investigate erosion prone areas in Edo State; the measure(s) were adopted to control gully erosion in the area and the effectiveness of the adopted measures across the study area. The research adopted questionnaire administration and direct field observation as methodo-logical approach. It was observed that control measures put in place in the study area include mechanical methods of back filling, sand bagging, construc-tion of channels and construction of speed breakers. The biological control methods in use are trees and crop planting. These control measures as observed during the fieldwork are partly successful as pointed out by respondents in their respective zones. Therefore, there is an urgent need to address this emerging looming disaster in the State.
Effect of Growth Morphology on the Electronic Structure of Epitaxial Graphene on SiC  [PDF]
Michael D. Williams, Dennis W. Hess
Graphene (Graphene) , 2013, DOI: 10.4236/graphene.2013.21008
Abstract: Ultraviolet photoemission spectroscopy is used to investigate the electronic structure of epitaxial graphene grown by the thermal decomposition of the carbon face of 4H SiC. We find that the growth of the film on the chemical mechanically polished and hydrogen etched surface enhances spectral features in the valence band structure compared to the film grown on an unpolished hydrogen etched substrate. This result is indicative of a more highly ordered surface structure compared to the morphologically rough material and shows that substrate preparation plays an important role in the quality of the film. The work function of the smooth surface film is found to be 0.4 eV higher than that for graphite and 0.1 eV less than for the rough surface growth.
Mutagenic and Genotoxic Screening of Eight Commonly used Skin Whitening Creams in Nigeria
EE Akortha, MT Niemogha, O Edobor
Bayero Journal of Pure and Applied Sciences , 2012,
Abstract: Skin whitening (bleaching) creams are often used to deliberately lighten the skin in response to social pressures or for the treatment of skin pigmentation. Bleaching creams contain varied concentrations of hydroquinone, corticosteroids, ammoniated mercury and kojic acid. Prolonged use of these creams may have deleterious (mutagenic) effect on the genetic material (DNA) of body cells. The purpose of this study was to evaluate the mutagenicity potentials of eight commonly used bleaching creams (Body white, Tura, Maxitone, Movate, Amos white, Top gel, Ultra clair, Fair and white), using the modified Ames test (with and without metabolic activation) that uses the wild type Escherichia coli (0157:H7) as tester strain. The assay was examined for revertant strains of the organism with at least three alterations in the phenotypic characteristics of the wild type organism. Results obtained showed that the eight bleaching creams produced revertant strains of the organism with alteration in more than three of its phenotypic characteristics and compared favourably with the standard mutagen (ethidium bromide), which produced the same effect. Three mutation mechanisms (forward, backward and silent mutations) were identified. The introduction of liver enzymes (S9 mix) made no significant difference in the number of characteristics altered (p>0.05). The results of this study revealed that the eight bleaching creams were mutagenic in bacteria and could be said to possess carcinogenic potentials. Their mechanism of mutagenesis could also be by intercalation just as ethidium bromide.
Gold in solar cells
Edward W. Williams
Gold Bulletin , 1980, DOI: 10.1007/BF03216545
Abstract: The cost of producing electricity from solar energy by means of solar cells is still high and limits the use of such devices to special situations. Gold has important roles not only in older types of cells but also in newer types which are being developed to achieve increased efficiencies.
Gold ion plating
E. W. Williams
Gold Bulletin , 1978, DOI: 10.1007/BF03215445
Abstract: The availability of a new technique for the application of thin gold coatings to a variety of substrate materials must be of interest to a large number of gold users. Gold ion plating offers a number of technical advantages over more traditional gold coating processes and it is to be expected that it will compete with such processes to an increasing extent.
W.E.B. Du Bois and His Social-Scientific Research: A Review of His Online Texts
Robert W. Williams
Sociation Today , 2005,
Abstract: The work of W.E.B. Du Bois which is available online is extensive. Williams provides a scholarly review of the work and life of Du Bois while documenting a very large amount of material available for students and the scholarly community in the online formats
A Note on the Life-Cycle of Tetraopes Femoratus Leconte (Cerambycid )
R. W. Williams
Psyche , 1941, DOI: 10.1155/1941/49829
Abstract:
Triboelectric charging of insulating polymers–some new perspectives
Meurig W. Williams
AIP Advances , 2012, DOI: 10.1063/1.3687233
Abstract: Tribolectric charging results from contact between surfaces, but precisely what is meant by each is not defined or understood, as they relate to charging. The recent microscopic evidence that contact charging can result from material transfer provides incentive to examine how contact charging is affected by these two factors. It is suggested that vigorous rubbing or pressing of two polymers results in transfer of deeper layers than would result from light contacts. Different layers can have substantially different compositions because polymers are typically not homogeneous as a function of depth, so contact and surface are related in this way. This could account for charge transfer between identical polymers, especially in asymmetric contacts in which the frictional force on one polymer differs from that on the other, so that material from different depths is transferred. This review outlines the roles of physics, chemistry and surface analysis in sufficient detail to focus on these subjects. It also makes suggestions how these concepts could be applied to some of the current leading edge research in this area.
The role of the epikarst in karst and cave hydrogeology: a review
Paul W. Williams
International Journal of Speleology , 2008,
Abstract: The epikarst (also known as the subcutaneous zone) comprises highly weathered carbonate bedrock immediately beneath the surface or beneath the soil (when present) or exposed at the surface. Porosity and permeability are higher near the surface than at depth, consequently after recharge percolating rainwater is detained near the base of the epikarst, the detention ponding producing an epikarstic aquifer. Such an aquifer is found only where the uppermost part of the vadose zone is very weathered compared to the bedrock at depth. Sometimes this contrast in porosity and permeability does not occur either because the epikarst has been scraped off by glacial scour or because high porosity exists throughout the bedrock. In some conditions porosity may even diminish near the surface because of case-hardening. The epikarst is best developed in pure, crystalline limestones or marble where it is typically about 10 m thick. It then contains a suspended aquifer that is under-drained and sustains the distal tributaries of cave streams and small perennial flows emerging on hillsides (epikarstic springs). Slow leakage paths from the epikarst maintain seepage to many stalactites throughout the year. A distinction should be recognized between the location (and form) of the epikarst and the function of the epikarst, because the near surface zone in carbonate rocks does not always contain a suspended aquifer.
Two-dimensional atomic lithography by sub-micron focusing of atomic beams
W. Williams,M. Saffman
Physics , 2005, DOI: 10.1364/JOSAB.23.001161
Abstract: We analyze a method for serial writing of arbitrary two-dimensional patterns using optical focusing of a collimated atomic beam. A spatial light modulator is used in a side illumination geometry to create a localized optical spot with secondary maxima that are well separated from the central peak. Numerical simulation of a lithography experiment using a magneto-optical trap as a source of cold Cs atoms, collimation and cooling in a magnetic guide, and optical focusing predicts full width at half maximum pixel sizes of 110 x 110 nm and writing times of about $20 \rm ms$ per pixel.
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