title: Numerical determination of parasitic resistances of a solar cell using the Lambert W-function

authors: Ghani, Faisal Abid

subjects: series resistance

abstract: Several methods are currently available to determine the values of series and shunt resistance of a solar cell. A new method is presented here to numerically locate these values using the popular Newton–Raphson technique at maximum power point. Equations based on the Lambert W-function and their partial derivatives are provided so that all calculations may be performed in a Matlab or similar environment. The results of this new method are presented and compared with two published methods and the analytically obtained for a blue and grey type solar cell in earlier work (Charles et al., 1981). Additionally, three modules of various type (single, poly, and amorphous crystalline) were investigated. Values determined agreed with experimentally verified results and were obtained with quadratic convergence in all instances provided initial estimates of the roots were within vicinity of the actual roots.

text: Numerical determination of parasitic resistances of a solar cell using the Lambert W-function Several methods are currently available to determine the values of series and shunt resistance of a solar cell. A new method is presented here to numerically locate these values using the popular Newton–Raphson technique at maximum power point. Equations based on the Lambert W-function and their partial derivatives are provided so that all calculations may be performed in a Matlab or similar environment. The results of this new method are presented and compared with two published methods and the analytically obtained for a blue and grey type solar cell in earlier work (Charles et al., 1981). Additionally, three modules of various type (single, poly, and amorphous crystalline) were investigated. Values determined agreed with experimentally verified results and were obtained with quadratic convergence in all instances provided initial estimates of the roots were within vicinity of the actual roots.

year: 2011

title: The occurrence and role of ubiquinone in electron transport to oxygen and nitrate in aerobically, anaerobically and symbiotically grown Rhizobium japonicum

authors: Daniel, Roy M.

subjects: Rhizobium japonicum

abstract: Ubiquinone was extracted from free-living Rhizobium japonicum, grown aerobically or anaerobically, and from the symbiotic bacteroid form; it was tentatively identified as the Q-10 homologue. The ubiquinone concentration was highest in symbiotically grown R. japonicum but the ratio ubiquinone:total cytochrome was about 1•5:1 in membrane particles from organisms grown under all three conditions. The ubiquinone was reduced 75% by NADH, completely oxidized by oxygen but not oxidized by nitrate. NADH oxidase activity and nitrate reductase activity in membrane particles from organisms grown under the different conditions were similar except that nitrate reductase activity was low in aerobically grown organisms. It is concluded that ubiquinone functions in electron transport to oxygen but not to nitrate.

text: The occurrence and role of ubiquinone in electron transport to oxygen and nitrate in aerobically, anaerobically and symbiotically grown Rhizobium japonicum Ubiquinone was extracted from free-living Rhizobium japonicum, grown aerobically or anaerobically, and from the symbiotic bacteroid form; it was tentatively identified as the Q-10 homologue. The ubiquinone concentration was highest in symbiotically grown R. japonicum but the ratio ubiquinone:total cytochrome was about 1•5:1 in membrane particles from organisms grown under all three conditions. The ubiquinone was reduced 75% by NADH, completely oxidized by oxygen but not oxidized by nitrate. NADH oxidase activity and nitrate reductase activity in membrane particles from organisms grown under the different conditions were similar except that nitrate reductase activity was low in aerobically grown organisms. It is concluded that ubiquinone functions in electron transport to oxygen but not to nitrate.

year: 1979

title: Mycobacterium tuberculosis strains in New Zealand: phylogeny and structural biology

authors: Claire Vignette, Mulholland

subjects: tuberculosis

abstract: Mycobacterium tuberculosis is an obligate human pathogen and is the primary causative agent of tuberculosis. New Zealand has a relatively low incidence of tuberculosis disease, however, Māori (the indigenous people of New Zealand) and Pacific People are disproportionally affected. Molecular typing shows that approximately two-thirds of M. tuberculosis isolates from New Zealand-born patients can be assigned to clusters of related strains. The largest M. tuberculosis cluster in New Zealand is known as the ‘Rangipo’ cluster and is predominantly found in Māori. This strain has been the source of several tuberculosis outbreaks over the last 30 years and anecdotal evidence suggests it may be particularly virulent. Two other large clusters, known as the ‘Southern Cross’ and ‘Otara’ clusters, most commonly occur in Pacific People.
Here, whole genome sequencing, phylogenetics and structural biology were used to investigate evolutionary origins and functional consequences of genomic diversity in New Zealand M. tuberculosis clusters, with a particular focus on the Rangipo strain. Analysis of Rangipo strain non-synonymous single nucleotide polymorphisms (nsSNPs) identified bacterial genetic factors that may contribute to the high transmissibility of this strain. The F420-dependent oxidoreductase Rv2893 harbours a Rangipo-specific G72S mutation encoded by a nsSNP. H37Rv and Rangipo Rv2893 structures were solved and show the effect of this G72S mutation. Binding of the F420 cofactor was confirmed and characterised. SNP analyses also guided the optimisation of a diagnostic assay for rapid Rangipo strain classification at low cost and with high discriminatory power. Phylogenetic analyses revealed the Rangipo and Otara clusters belong to a larger M.tuberculosis clade of French/European origin that is also prevalent in indigenous populations in Canada. Molecular dating indicates dispersal of this clade to the South Pacific was driven by expanding European trade networks in the early 19th century and identifies host factors that have contributed to the dispersal and expansion of the Rangipo and Otara strains.
Overall, these results show that relatively recent changes in host ecology have likely played a crucial role in driving the success of the Rangipo strain in New Zealand and point to bacterial genetic factors that may influence its virulence and thereby also contribute to its prevalence.

text: Mycobacterium tuberculosis strains in New Zealand: phylogeny and structural biology Mycobacterium tuberculosis is an obligate human pathogen and is the primary causative agent of tuberculosis. New Zealand has a relatively low incidence of tuberculosis disease, however, Māori (the indigenous people of New Zealand) and Pacific People are disproportionally affected. Molecular typing shows that approximately two-thirds of M. tuberculosis isolates from New Zealand-born patients can be assigned to clusters of related strains. The largest M. tuberculosis cluster in New Zealand is known as the ‘Rangipo’ cluster and is predominantly found in Māori. This strain has been the source of several tuberculosis outbreaks over the last 30 years and anecdotal evidence suggests it may be particularly virulent. Two other large clusters, known as the ‘Southern Cross’ and ‘Otara’ clusters, most commonly occur in Pacific People.
Here, whole genome sequencing, phylogenetics and structural biology were used to investigate evolutionary origins and functional consequences of genomic diversity in New Zealand M. tuberculosis clusters, with a particular focus on the Rangipo strain. Analysis of Rangipo strain non-synonymous single nucleotide polymorphisms (nsSNPs) identified bacterial genetic factors that may contribute to the high transmissibility of this strain. The F420-dependent oxidoreductase Rv2893 harbours a Rangipo-specific G72S mutation encoded by a nsSNP. H37Rv and Rangipo Rv2893 structures were solved and show the effect of this G72S mutation. Binding of the F420 cofactor was confirmed and characterised. SNP analyses also guided the optimisation of a diagnostic assay for rapid Rangipo strain classification at low cost and with high discriminatory power. Phylogenetic analyses revealed the Rangipo and Otara clusters belong to a larger M.tuberculosis clade of French/European origin that is also prevalent in indigenous populations in Canada. Molecular dating indicates dispersal of this clade to the South Pacific was driven by expanding European trade networks in the early 19th century and identifies host factors that have contributed to the dispersal and expansion of the Rangipo and Otara strains.
Overall, these results show that relatively recent changes in host ecology have likely played a crucial role in driving the success of the Rangipo strain in New Zealand and point to bacterial genetic factors that may influence its virulence and thereby also contribute to its prevalence.

year: 2019