Search results for "mixture"
showing 10 items of 1178 documents
The effect of oxygenation on the radiation hardness of silicon studied by surface photovoltage method
2002
The effect of oxygenation on the radiation hardness of silicon detectors was studied. Oxygen-enriched and standard float-zone silicon pin-diodes and oxidized samples were processed and irradiated with 15-MeV protons. After the irradiations, the surface photovoltage (SPV) method was applied to extract minority carrier diffusion lengths of the silicon samples. Adding oxygen to silicon was found to improve the radiation hardness of silicon. The effect was visible in minority carrier diffusion lengths as well as in reverse bias leakage currents. The suitability of SPV method for characterizing irradiated silicon samples was proved.
Annealing study of oxygenated and non-oxygenated float zone silicon irradiated with protons
2003
Abstract Introducing oxygen into the silicon material is believed to improve the radiation hardness of silicon detectors. In this study, oxygenated and non-oxygenated silicon samples were processed and irradiated with 15 MeV protons. In order to speed up the defect reactions after the exposure to particle radiation, the samples were heat treated at elevated temperatures. In this way, the long-term stability of silicon detectors in hostile radiation environment could be estimated. Current–voltage measurements and Surface Photovoltage (SPV) method were used to characterize the samples.
FeOOH-modified clay sorbents for arsenic removal from aqueous solutions
2019
The presence of arsenic (As) in natural and anthropogenic soils causes severe pollution of groundwater due to its harmful carcinogenic effects. The present work describes the research activities for searching of appropriate innovative sorbents based on clay material for As sorption using iron oxy-hydroxide modification. Natural and manufactured clay was chosen for comparison of modification efficiency in order to obtain best sorption results for As(V). The results of pilot testing were obtained and the sorption was studied as a function of initial arsenic concentration. Obtained results indicate that modification of clay with Fe compounds significantly improves the sorption capacity of a ne…
Birefringent porous silicon membranes for optical sensing
2012
In this work anisotropic porous silicon is investigated as a material for optical sensing. Birefringence and sensitivity of the anisotropic porous silicon membranes are thoroughly studied in the framework of Bruggeman model which is extended to incorporate the influence of environment effects, such as silicon oxidation. The membranes were also characterized optically demonstrating sensitivity as high as 1245 nm/RIU at 1500 nm. This experimental value only agrees with the theory when it takes into consideration the effect of silicon oxidation. Furthermore we demonstrate that oxidized porous silicon membranes have optical parameters with long term stability. Finally, we developed a new model …
The measurement of impurities in silicon for solar cell production
2012
The power conversion efficiency of solar cells is largely dependent on impurity levels in silicon. In the current investigations two sample preparation methods of silicon had been used before analysis - acid dissolution at atmospheric pressure and pressured microwave assisted technique. Quantification of impurities in solar silicon was done by inductively coupled plasma mass spectrometry and electrothermal atomic spectrometry. Microwave assisted dissolution of solar silicon was more effective compared to the traditional dissolution method on the hot plate, but complete dissolution of impurities and silicon matrix was achieved with a nitric and hydrofluoric acid mixture. The mass of solar si…
Change and stability of sense of coherence in adulthood: Longitudinal evidence from the Healthy Child study
2007
Abstract The main aim of this three-wave 35-year follow-up study among Finnish employees ( n = 532) was to investigate whether Sense of Coherence (SOC) is more stable among those with high SOC compared to those with low SOC, as hypothesized by Antonovsky [Antonovsky, A. (1987). Unraveling the mystery of health: how people manage stress and stay well. San Francisco, CA, US: Jossey-Bass], using two measurement points over 13 years. The participants were first studied in adolescence in 1961–1963, after which they responded to two postal questionnaires measuring SOC, first in 1985, and again in 1998. The results of the Factor Mixture Modeling identified two groups of individuals with different…
Wood Ash Effects on Soil Fauna and Interactions with Carbohydrate Supply: A Minireview
2011
Wood ash effects on soil animals in a boreal forest ecosystem are reviewed focusing on recent results on interactive effects of wood ash and organic amendments, and laboratory microcosms as a tool to understand soil food webs are discussed. Loose wood ash can reduce the populations of enchytraeids, collembolans and mites, but increase nematode populations particularly in experimental laboratory ecosystems with little or no primary production. Recent studies indicate that the repressive effect on enchytraeids depends on carbon availability. Carbohydrate supply seemed to alleviate the negative wood ash effect on enchytraeid body size and abundance. The fact that carbon alleviated wood ash eff…
Novel organo-modifier for thermally-stable polymer-layered silicate nanocomposites
2015
A new novel approach for the stabilisation of polymer-clay nanocomposites has been investigated based on reacting chemically an antioxidant function, a hindered phenol moiety, with an organic modifier based on a quaternary ammonium salt. The chemically linked antioxidant-containing organic modifier (AO-OM) was then introduced into natural montmorillonite (MMt) through a cation-exchange reaction resulting in antioxidant-containing organo-modified clay (AO-OM-MMt). The new antioxidant-containing modified clay, along with other organo-modified clays having a similar organo-modifier but without the reacted antioxidant, were characterised by spectroscopic, thermogravimetric and x-ray diffraction…
"Table 1" of "Few neutron removal from U-238 at relativistic energies"
1997
Uranium fragmentation.
"Table 2" of "Few neutron removal from U-238 at relativistic energies"
1997
Uranium fragmentation.