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Search Results: 1 - 10 of 551 matches for " recombination "
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The Efficiency of a p-n Solar Diode as a Function of the Recombination Velocity within the Depletion Layer  [PDF]
Mohamed K. El-Adawi, Najla S. Al-Shameri
Optics and Photonics Journal (OPJ) , 2012, DOI: 10.4236/opj.2012.24040

The role of the carrier’s recombination velocity Si within the depletion Layer of p-n junction solar cell and the external bias voltage Va across the junction in determining the current density “J” through the cell is revealed. The unsteady carrier diffusion equation is solved under illumination conditions considering a source spectral function G(λ). The efficiency of the device as a function of Si , Va , G(λ) is obtained. Computations considering a silicon solar cell are given as an illustrative example.

Analysis of the Hypervariable Regions (HVRs) of the wsp Gene of Wolbachia from Solenopsis invicta Ants in Southeastern Brazil  [PDF]
Rodrigo Fernando de Souza, Cíntia Martins, Roberto Manoel Pereira, Odair Correa Bueno
Advances in Entomology (AE) , 2014, DOI: 10.4236/ae.2014.23021
Abstract: Wolbachia is a bacterium that infects many arthropods with horizontal or vertical transmission. The introduction and spreading of Solenopsis invicta in new areas may have influenced the acquisition of Wolbachia as this ant species spread from its South America origin to other parts of the globe. The wsp gene of Wolbachia was analyzed using the WSP Typing and a similarity analysis was conducted to analyse the sharing of the symbiont among nests of S. invicta ants. The analyses revealed the presence of two groups of Wolbachia: strain A belonging to InvA S. invicta subgroup, and the strain B belonging to Acromyrmex insinuator. The wsp gene and its hypervariable regions are shared among the Wolbachia present in different types of ants inhabiting in the New World. Wolbachia strains found in the nests of S. invicta are ant-specialist symbionts which may have spread by several means among the ant population.
A method to synthesize cDNA constructs by homology based recombination cloning  [PDF]
Neetu Verma, Pradeep Kumar Burma
American Journal of Molecular Biology (AJMB) , 2014, DOI: 10.4236/ajmb.2014.41003

We introduce a homology-based recombination approach for generating a cDNA construct. This method depends on amplifying several exon fragments and their fusions by the homology-based recombination. This method provides a way to generate the cDNA sequence of any gene without any need for its mRNA. The paper describes the strategy by assembling cDNA of the MYB1 and MYB2 genes of Arabidopsis thaliana.

Impact of Sequence Non-Identities on Recombination within the pil System of Neisseria gonorrhoeae  [PDF]
Stuart A. Hill, Jenny Wachter
Open Journal of Genetics (OJGen) , 2014, DOI: 10.4236/ojgen.2014.43023

Neisseria gonorrhoeae engages in extensive intra-cellular gene conversion between the PilE-expression locus (pilE) and the transcriptionally-silent pil gene copies (pilS). In silico analyses were applied to investigate the extent of sequence heterogeneity between the various pilS gene copies. Analysis of synonymous and non-synonymous substitutions between the different pilS genes indicated that relatively few amino acid changes would occur due to nucleotide polymorphisms towards the 5’ end of the pilS genes whereas more frequent amino acid substitutions would be incorporated within the “hypervariable” region. The lack of non-synonymous substitutions at the 5’ end of the genes was found to be under selective pressure as indicated by a positive DT score utilizing the Tajima test. The presence or absence of mismatch repair appeared to only impact recombination when non-identical DNAs recombined via the DNA transformation route, where small pil sequence heterogeneities were sufficient to terminate recombination tracts, with these sequence constraints being relieved in cells carrying a mutS mutation. Therefore, the data indicate that the effect of sequence heterogeneity on recombination within the pil

Modelling Study of Magnetic Field’s Effects on Solar Cell’s Transient Decay  [PDF]
Senghane Mbodji, Martial Zoungrana, Issa Zerbo, Biram Dieng, Gregoire Sissoko
World Journal of Condensed Matter Physics (WJCMP) , 2015, DOI: 10.4236/wjcmp.2015.54029
Abstract: Experimental setup of transient decay which occurs between two steady state operating points is recalled. The continuity equation is resolved using both the junction dynamic velocity (Sf) and back side recombination velocity (Sb). The transient excess minority carriers density appears as the sum of infinite terms. Influence of magnetic field on the transient excess minority carriers density and transient photo voltage is studied and it is demonstrated that the use of this technique is valid only when the magnetic field is lower than 0.001 T.
Back Surface Recombination Velocity Modeling in White Biased Silicon Solar Cell under Steady State  [PDF]
Ousmane Diasse, Amadou Diao, Mamadou Wade, Marcel Sitor Diouf, Ibrahima Diatta, Richard Mane, Youssou Traore, Gregoire Sissoko
Journal of Modern Physics (JMP) , 2018, DOI: 10.4236/jmp.2018.92012
Abstract: In this paper, we extend the concept of back surface recombination through a study of a silicon mono facial solar cell in static regime and under polychromatic illumination. Back surface recombination velocities noted Sbe, Sbj and Sbr are determined for which respectively we derived, the power, the fill factor and the conversion efficiency, that become constant whatever the thickness of the solar cell. We have then obtained the expression of the minority carrier’s density in the base from the continuity equation. We then have determined the photocurrent density, the photo voltage, the power, the fill factor and finally the conversion efficiency.
Analysis of T-Coefficients Using the Columnar Cylindrical Orientation of Solar Cell Grain  [PDF]
Serigne Ndiangue Leye, Ibrahima Fall, Senghane Mbodji, Papa Lat Tabara Sow, Gregoire Sissoko
Smart Grid and Renewable Energy (SGRE) , 2018, DOI: 10.4236/sgre.2018.93004
Abstract: We report the study of the temperature dependance of the performance electronic parameters of an N-P solar cell by considering as model, the columnar cylindrical orientation associated to the dynamic junction velocity (SF) concept. We presented the photocurrent-photovoltage (I-V) and Power-photovoltage (P-V) characteristic curves. The short-circuit photocurrent (Isc), the open circuit photovoltage (Uoc), the fill factor (FF) and the efficiency (η) are linearly dependent on the temperature. The temperature coefficients (T-coefficient) relative to the short-circuit, open-circuit photovoltage and efficiency are calculated and the comparison with data from the literature showed the accuracy of the considered model.
A 3D Modelling of Solar Cell’s Electric Power under Real Operating Point  [PDF]
Mayoro Dieye, Senghane Mbodji, Martial Zoungrana, Issa Zerbo, Biram Dieng, Gregoire Sissoko
World Journal of Condensed Matter Physics (WJCMP) , 2015, DOI: 10.4236/wjcmp.2015.54028
Abstract: This work, based on the junction recombination velocity (Sfu) concept, is used to study the solar cell’s electric power at any real operating point. Using Sfu and the back side recombination velocity (Sbu) in a 3D modelling study, the continuity equation is resolved. We determined the photocurrent density, the photovoltage and the solar cell’s electric power which is a calibrated function of the junction recombination velocity (Sfu). Plots of solar cell’s electric power with the junction recombination velocity give the maximum solar cell’s electric power, Pm. Influence of various parameters such as grain size (g), grain boundaries recombination velocity (Sgb), wavelength (λ) and for different illumination modes on the solar cell’s electric power is studied.
Influence of Recombination Centers on the Phase Portraits in Nanosized Semiconductor Films  [PDF]
Gafur Gulyamov, Abdurasul G. Gulyamov, Feruza R. Muhitdinova
Journal of Modern Physics (JMP) , 2016, DOI: 10.4236/jmp.2016.713151
Abstract: Influence of recombination centers’ changes on the form of phase portraits has been studied. It has been shown that the shape of the phase portraits depends on the concentration of semiconductor materials’ recombination centers.
Study of Nonradiative Recombination Centers in n-GaN Grown on LT-GaN and AlN Buffer Layer by Below-Gap Excitation  [PDF]
M. D. Haque, M. Julkarnain, A. Z. M. Touhidul Islam, N. Kamata
Advances in Materials Physics and Chemistry (AMPC) , 2018, DOI: 10.4236/ampc.2018.83010
Abstract: Nonradiative recombination (NRR) centers in n-type GaN samples grown by MOCVD technique on a LT-GaN buffer layer and aAlN buffer layer have been studied by two wavelength excited photoluminescence (TWEPL). The near band-edge photoluminescence (PL) intensity decreases due to the superposition of below-gap excitation (BGE) light of energies 0.93, 1.17 and 1.27 eV over above-gap excitation (AGE) light of energy 4.66 eV. The decrease in PL intensity due to the addition of the BGE has been explained by a two levels recombination model based on SRH statistics. It indicates the presence of a pair of NRR centers in both samples, which are activated by the BGE. The degree of quenching in PL intensity for the sample grown on LT-GaN buffer layer is stronger than the sample grown on AlN buffer layer for all BGE sources. This result implies that the use of the AlN buffer layer is more effective for reducing the NRR centers in n-GaN layers than the LT-GaN buffer layer. The dependence of PL quenching on the AGE density, the BGE density and temperature has been also investigated. The NRR parameters have been quantitatively determined by solving rate equations and fitting the simulated results with the experimental data.
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