Filament identification and dominance of Eikelboom Type 0092 in activated sludge from wastewater treatment facilities in Cape Town, South Africa

Routine characterisation of activated sludge and identification of the filamentous population by microscopic and/or other non-culture dependent techniques can assist in diagnosing the aetiology of poor performance of wastewater treatment works (WWTWs). In South Africa, most facilities rely solely on physicochemical indicators, treating reactors as ‘black-boxes’, with the result that process adjustments are often delayed, to the detriment of the environment. This study was performed in order to gain insight into the filamentous population found in activated sludge in Cape Town WWTWs, to compare these with other global and local literature findings, and to build capacity in this science. Physicochemical and plant performance parameters, in terms of nutrient removal and settling, were obtained from routine operational data and assessed in conjunction with the microscopic analyses of activated sludge samples taken over a 6-month period. Hypotheses on the links between filament types and/or plant  configurations and/or operational parameters were formulated using  existing literature. In order of prevalence, the five most common dominant filament species in 96 activated sludge samples were: Eikelboom Type  0092, Eikelboom Type 1851, nocardioforms, Microthrix parvicella and  Eikelboom Type 021N. In order to compile a statistically significant  database, it is recommended that an extensive nationwide study is  conducted to link filament types with plant configurations, operational parameters and geographical locations.Keywords: activated sludge, bulking, identification, filament, Type 009

Sequence-based prediction for vaccine strain selection and identification of antigenic variability in foot-and-mouth disease virus

Identifying when past exposure to an infectious disease will protect against newly emerging strains is central to understanding the spread and the severity of epidemics, but the prediction of viral cross-protection remains an important unsolved problem. For foot-and-mouth disease virus (FMDV) research in particular, improved methods for predicting this cross-protection are critical for predicting the severity of outbreaks within endemic settings where multiple serotypes and subtypes commonly co-circulate, as well as for deciding whether appropriate vaccine(s) exist and how much they could mitigate the effects of any outbreak. To identify antigenic relationships and their predictors, we used linear mixed effects models to account for variation in pairwise cross-neutralization titres using only viral sequences and structural data. We identified those substitutions in surface-exposed structural proteins that are correlates of loss of cross-reactivity. These allowed prediction of both the best vaccine match for any single virus and the breadth of coverage of new vaccine candidates from their capsid sequences as effectively as or better than serology. Sub-sequences chosen by the model-building process all contained sites that are known epitopes on other serotypes. Furthermore, for the SAT1 serotype, for which epitopes have never previously been identified, we provide strong evidence - by controlling for phylogenetic structure - for the presence of three epitopes across a panel of viruses and quantify the relative significance of some individual residues in determining cross-neutralization. Identifying and quantifying the importance of sites that predict viral strain cross-reactivity not just for single viruses but across entire serotypes can help in the design of vaccines with better targeting and broader coverage. These techniques can be generalized to any infectious agents where cross-reactivity assays have been carried out. As the parameterization uses pre-existing datasets, this approach quickly and cheaply increases both our understanding of antigenic relationships and our power to control disease

Penta-carbonyl-25 C-chlorido-1Cl-bis-[1(5)-cyclo- penta-dien-yl]( - Oxido-benzyl-idene-1:2κ2 O:C)titanium(IV) tungsten(0)

The title compound, [TiW(C5H5)2(C7H5O)Cl(CO)5], consists of two metal centres, with a (tungstenpenta-carbon-yl)oxy-phenyl-carbene unit coordinated by a titanocene chloride. The oxycarbene group is nearly planar, with the phenyl ring twisted by an angle of 39.1 (2)° with respect to this plane. One of the cyclo-penta-dienyl rings undergoes an offset face-to-face π-π inter-action [3.544 (6) Å] with the symmetry-related cyclo-penta-dienyl ring of a neighbouring mol-ecule. © 2008.Articl

OHphenol⋯OHalcohol hydrogen-bonding as the preferred hydrogen-bonded interaction in the crystal structures of three isomers of methylolphenol: Analysis of hydrogen-bonding interactions in phenol and alcohol containing molecules

The crystal structures of three isomers containing a phenol and an alcohol functional group, 2-methylolphenol (1), 3-methylolphenol (2) and 4-methylolphenol (3) are reported. All isomers feature heteromeric hydrogen bonded interactions, either from the phenol hydrogen to the alcohol O or from the alcohol hydrogen to the phenol O. There are no homomeric interactions present in the solid state. An analysis of 31 related compounds shows that in the literature the OHphenol⋯OHalcohol hydrogen bond is the most commonly seen heteromeric interaction in these types of compounds, and DFT calculations show that this hydrogen bond has the highest interaction energy in the three isomers. The isomer 3-methylolphenol (2) crystallizes as two concomitant polymorphs, 2a containing two molecules in the asymmetric unit, and 2b containing three molecules in the asymmetric unit, with the former slightly more stable according to DFT calculations. © The Royal Society of Chemistry 2011.Articl

Complexation behavior of two-coordinated carbon compounds containing fluorenyl ligands

Please help populate SUNScholar with the full text of SU research output. Also - should you need this item urgently, please send us the details and we will try to get hold of the full text as quick possible. E-mail to [email protected]. Thank you.Journal Articles (subsidised)NatuurwetenskappeChemie & Polimeerwetenska

Distinguishing carbones from allenes by complexation to AuCl

Quantum chemical calculations have been performed for the dicoordinated carbon compounds C(PPh3)2, C(NHCMe) 2, R2C=C=CR2 (R=H, F, NMe2), C 3O2, C(CN)2- and N-methyl-substituted N-heterocyclic carbene (NHCMe). The geometries of the complexes in which the dicoordinated carbon molecules bind as ligands to one and two AuCl moieties have been optimized and the strength and nature of the metal-ligand interactions in the mono- and diaurated complexes were investigated by means of energy decomposition analysis. The goal of the study is to elucidate the differences in the chemical behavior between carbones, allenes and carbenes. The results show that carbones bind one and two AuCl species in η1 fashion, whereas allenes bind them in η2 fashion. Compounds with latent divalent carbon(0) character can coordinate in more than one way, with the dominant mode indicating the degree of carbone or allene character. The calculated structures of the mono- and diaurated tetraaminoallenes (TAAs) reveal that TAAs exhibit a chameleon-like behavior: The bonding situation in the equilibrium structure is best described as allene [(R2N)2]C=C=C[(NR 2)2] in which the central carbon atom is a tetravalent CIV species, but the reactivity suggests that TAAs should be considered as divalent C0 compounds C{C[(NR2) 2]}2, that is, as "hidden" carbones. Carbon suboxide binds one AuCl preferentially in the η1 mode, whereas the equilibrium structures of the η1- and η2-bonded diaurated complex are energetically nearly degenerate. The doubly negatively charged isoelectronic carbone C(CN) 22- binds one and two AuCl very strongly in characteristic η1 fashion. The N-heterocyclic carbene complex, [NHCMe(AuCl)], possesses a high bond dissociation energy (BDE) for the splitting off of AuCl. The diaurated NHC adduct, [NHCMe(AuCl) 2], has two η1-bonded AuCl moieties that exhibit aurophilic attraction, which yield a moderate bond strength that might be large enough for synthesizing the complex. The BDE for the second AuCl in [NHCMe(AuCl)2] is clearly smaller than the values for the second AuCl in doubly aurated carbone complexes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Articl

Thioether- and Selenoether-carboxylates in palladium chemistry: Conclusive proof of hemilabile properties of O-Se ligands.

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The nature of the chemical bond revisited. An energy partitioning analysis of diatomic molecules E<SUB>2</SUB> (<I>E</I> = N-Bi, F-I), CO and BF

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Aurolysis of α-C-deprotonated group 6 aminocarbene and thiocarbene complexes with Ph3PAu+

Deprotonated Fischer-type aminocarbene complexes, (CO) 5MC(NR2)CH3 (M = Cr or W; R = Me or propyl), react with Ph3PAu+ by metal group substitution - (CO) 5M for Ph3PAu+ - and attachment of the extricated M(CO)5 to the deprotonated methyl group. (The products may also be seen as aminovinylgold compounds coordinated to M(CO)5 moieties.) DFT calculations at the B3LYP level of theory using model compounds indicate a clear preference of the gold unit for central C to terminal coordination in the ligand [NMe2CCH2]-, whereas the Cr(CO)5 has a 7 kcal mol-1 preference for C(vinyl) coordination compared to N-coordination. In related thiocarbenes, the sulfur donor atom should be the preferred point of attachment for the metal carbonyl unit. The latter prediction is borne out in practice, and in the three products isolated, including Ph3PAu{C(CH2)SPh}Cr(CO)5 in a mixed crystal with [Ph3PAuSPh]Cr(CO)5, precisely this coordination mode is present. The latter component of the mixed crystal has also been prepared independently of the vinyl one. © The Royal Society of Chemistry 2006.Articl

Pentacarbonyl[methyl(n-propylsulfanyl)-carbene]chromium(0)

The title compound, [Cr(C5H10S)(CO)5], comprises a methyl(n-propylsulfanyl)carbene ligand coordinated to a pentacarbonylchromium fragment, with the Cr atom in an octahedral coordination. © 2006 International Union of Crystallography. All rights reserved.Articl