Depolymerisation and biodegradation of a synthetic tanning agent by activated sludges, the bacteria Arthrobacter globiformis and Comamonas testosteroni, and the fungus Cunninghamella polymorpha

Degradation of a synthetic tanning agent CNSF (a condensation product of 2-naphthatenesulfonic acid (2-NSA) and formaldehyde) by four activated sludges, two previously characterised bacterial strains, Arthrobacter sp. 2AC and Comamonas sp. 4BC, and the fungus Cunninghamella polymorpha, was studied in batch culture at 25 degrees C by determining the changes in the concentrations of CNSF and its component monomers and oligomers (n2-n11). The loss of individual oligomers was correlated with the length of the NSA-CH2 chain. Approximately 25% of the total CNSF was degraded (i.e. mineralised) by the microbes contained in the four activated sludges and by the two bacterial isolates but with different lag phases and at different overall rates. The decline in CNSF concentration was due almost entirely to the biodegradation of the monomers (34.3% of CNSF) and, in particular, 2-NSA (27% of CNSF). There was no change in the n2-n 11 components. The growth of C. polymorpha, on the other hand, arose from extracellular depolymerisation of CNSF oligomers and the biodegradation of the lower molecular mass products. Between 38% and 42% of total CNSF was degraded by C. polymorpha at 25 degrees C. The order of oligomer degradation was inversely related to degree of polymerisation. Eighty percent and 90% of the n4 and n5 and 100% oligomers n6-n11 were degraded after 120 h. At a higher temperature (37 degrees C) oligomers n4-n11 were degraded completely after 120 h. A combination of biodegradation (75%) and sorption to fungal biomass (25%) accounted for the measured loss of all oligomers from the solution phase. The CNSF degradation rates and the volume of fungal biomass produced (and therefore the extent of biosorption) were dependent on the presence of a second carbon source (both optimum at glucose 5 g/l). This is the first report that identifies and distinguishes between depolymerisation, sorption and biodegradation processes in the removal of CNSF and its component oligomers. The use of combinations of the depolymerising fungus C. polymorpha, and the monomer-degrading bacteria, Arthrobacter sp. 2AC and Comamonas sp. 4BC, have potential for wastewater treatment.

A quantum yield map for synthetic eumelanin

The quantum yield of synthetic eumelanin is known to be extremely low and it has recently been reported to be dependent on excitation wavelength. In this paper, we present quantum yield as a function of excitation wavelength between 250 and 500 nm, showing it to be a factor of 4 higher at 250 nm than at 500 nm. In addition, we present a definitive map of the steady-state fluorescence as a function of excitation and emission wavelengths, and significantly, a three-dimensional map of the specific quantum yield: the fraction of photons absorbed at each wavelength that are subsequently radiated at each emission wavelength. This map contains clear features, which we attribute to certain structural models, and shows that radiative emission and specific quantum yield are negligible at emission wavelengths outside the range of 585 and 385 nm (2.2 and 3.2 eV), regardless of excitation wavelength. This information is important in the context of understanding melanin biofunctionality, and the quantum molecular biophysics therein. (c) 2005 American Institute of Physics.

Quantitative fluorescence excitation spectra of synthetic eumelanin

Previously reported excitation spectra for eumelanin are sparse and inconsistent. Moreover, these studies have failed to account for probe beam attenuation and emission reabsorption within the samples, making them qualitative at best. We report for the first time quantitative excitation spectra for synthetic eumelanin, acquired for a range of solution concentrations and emission wavelengths. Our data indicate that probe beam attenuation and emission reabsorption significantly affect the spectra even in low-concentration eumelanin solutions and that previously published data do not reflect the true excitation profile. We apply a correction procedure (previously applied to emission spectra) to account for these effects. Application of this procedure reconstructs the expected relationship of signal intensity with concentration, and the normalized spectra show a similarity in form to the absorption profiles. These spectra reveal valuable information regarding the photophysics and photochemistry of eumelanin. Most notably, an excitation peak at 365 urn (3.40 eV), whose position is independent of emission wavelength, is possibly attributable to a 5,6-dihydroxyindole-2-carboxylic acid (DHICA) component singly linked to a polymeric structure.

Synthetic, EPR spectroscopic, magnetic and X-ray crystallographic structural studies on copper(II) complexes of the tridentate N2S donor ligand formed from 6-methyl-2-formylpyridine and S-methyldithiocarbazate (Hmpsme)

New copper(II) complexes of general empirical formula, Cu(mpsme)X center dot xCH(3)COCH(3) (mpsme = anionic form of the 6-methyl-2-formylpyridine Schiff base of S-methyldithiocarbazate; X = Cl, N-3, NCS, NO3; x = 0, 0.5) have been synthesized and characterized by IR, electronic, EPR and susceptibility measurements. Room temperature mu(eff) values for the complexes are in the range 1.75-2.1 mu(beta) typical of uncoupled or weakly coupled Cu(II) centres. The EPR spectra of the [Cu(mpsme)X] (X = Cl, N-3, NO3, NCS) complexes reveal a tetragonally distorted coordination sphere around the mononuclear Cu(II) centre. We have exploited second derivative EPR spectra in conjunction with Fourier filtering (sine bell and Hamming functions) to extract all of the nitrogen hyperfine coupling matrices. While the X-ray crystallography of [Cu(mpsme)NCS] reveals a linear polymer in which the thiocyanate anion bridges the two copper(II) ions, the EPR spectra in solution are typical of a magnetically isolated monomeric Cu(II) centres indicating dissociation of the polymeric chain in solution. The structures of the free ligand, Hmpsme and the {[Cu(mpsme)NO3] center dot 0.5CH(3)COCH(3)}(2) and [Cu(mpsme)NCS](n) complexes have been determined by X-ray diffraction. The {[Cu(mpsme)NO3]0.5CH(3)COCH(3)}(2) complex is a centrosymmetric dimer in which each copper atom adopts a five-coordinate distorted square-pyramidal geometry with an N2OS2 coordination environment, the Schiff base coordinating as a uninegatively charged tridentate ligand chelating through the pyridine and azomethine nitrogen atoms and the thiolate, an oxygen atom of a unidentate nitrato ligand and a bridging sulfur atom from the second ligand completing the coordination sphere. The [Cu(mpsme)(NCS)](n) complex has a novel staircase-like one dimensional polymeric structure in which the NCS- ligands bridge two adjacent copper(II) ions asymmetrically in an end-to-end fashion providing its nitrogen atom to one copper and the sulfur atom to the other. (c) 2005 Elsevier B.V. All rights reserved.

Minimising cold damage during reproductive development among temperate rice genotypes. I. Avoiding low temperature with the use of appropriate sowing time and photoperiod-sensitive varieties

Multiple-sown field trials in 4 consecutive years in the Riverina region of south-eastern Australia provided 24 different combinations of temperature and day length, which enabled the development of crop phenology models. A crop model was developed for 7 cultivars from diverse origins to identify if photoperiod sensitivity is involved in determining phenological development, and if that is advantageous in avoiding low-temperature damage. Cultivars that were mildly photoperiod-sensitive were identified from sowing to flowering and from panicle initiation to flowering. The crop models were run for 47 years of temperature data to quantify the risk of encountering low temperature during the critical young microspore stage for 5 different sowing dates. Cultivars that were mildly photoperiod-sensitive, such as Amaroo, had a reduced likelihood of encountering low temperature for a wider range of sowing dates compared with photoperiod-insensitive cultivars. The benefits of increased photoperiod sensitivity include greater sowing flexibility and reduced water use as growth duration is shortened when sowing is delayed. Determining the optimal sowing date also requires other considerations, e. g. the risk of cold damage at other sensitive stages such as flowering and the response of yield to a delay in flowering under non-limiting conditions. It was concluded that appropriate sowing time and the use of photoperiod-sensitive cultivars can be advantageous in the Riverina region in avoiding low temperature damage during reproductive development.

Need for systematic synthetic phonics teaching within the early reading curriculum

Both the New Zealand Ministry of Education's Literacy Experts Group and the Australian National Inquiry into the Teaching of Literacy have recently acknowledged the centrality of systematic instruction in synthetic phonics to early reading instruction, but this conclusion remains contentious in some circles. This paper briefly summarises empirical research in basic psychology and evidence-based evaluation studies supporting the inclusion of systematic synthetic phonics instruction within the early reading curriculum, allowing practising psychologists to develop an informed opinion on this issue.

Spectroscopic studies of synthetic and natural beidellites: A review

This paper represents an overview of the spectroscopic studies of both synthetic and naturally occurring beidellites performed as part of my research over the past 16 years. It shows that detailed information on the local structure of beidellite and changes in this local structure upon heating can be obtained by combining a range of spectroscopic techniques such as mid-infrared, near-infrared, infrared emission, Raman, nuclear magnetic resonance and X-ray photoelectron spectroscopy.

Varieties of algebras arising from K-perfect m-cycle systems

A class of algebras forms a variety if it is characterised by a collection of identities. There is a well-known method, often called the standard construction, which gives rise to algebras from m-cycle systems. It is known that the algebras arising from {1}-perfect m-cycle systems form a variety for m is an element of {3, 5} only, and that the algebras arising from {1, 2}-perfect m-cycle systems form a variety for m is an element of {3, 5, 7} only. Here we give, for any set K of positive integers, necessary and sufficient conditions under which the algebras arising from K-perfect m-cycle systems form a variety. (c) 2006 Elsevier B.V. All rights reserved.