Geometric and electronic information from the spectroscopy of six-coordinate copper(II) compounds

The ground and excited state geometry of the six-coordinate copper(II) ion is examined in detail using the CuF64- and Cu(H2O)(6)(2+) complexes as examples. A variety of spectroscopic techniques are used to illustrate the relations between the geometric and electronic properties of these complexes through the characterization of their potential energy surfaces.

Sensitivity and uncertainty analyses for burden of disease and risk factor estimates

Epidemiological studies report confidence or uncertainty intervals around their estimates. Estimates of the burden of diseases and risk factors are subject to a broader range of uncertainty because of the combination of multiple data sources and value choices. Sensitivity analysis can be used to examine the effects of social values that have been incorporated into the design of the disability–adjusted life year (DALY). Age weight, where a year of healthy life lived at one age is valued differently from at another age, is the most controversial value built into the DALY. The discount rate, which addresses the difference in value of current versus future health benefits, also has been criticized. The distribution of the global disease burden and rankings of various conditions are largely insensitive to alternate assumptions about the discount rate and age weighting. The major effects of discounting and age weighting are to enhance the importance of neuropsychiatric conditions and sexually transmitted infections. The Global Burden of Disease study also has been criticized for estimating mortality and disease burden for regions using incomplete and uncertain data. Including uncertain results, with uncertainty quantified to the extent possible, is preferable, however, to leaving blank cells in tables intended to provide policy makers with an overall assessment of burden of disease. No estimate is generally interpreted as no problem. Greater investment in getting the descriptive epidemiology of diseases and injuries correct in poor countries will do vastly more to reduce uncertainty in disease burden assessments than a philosophical debate about the appropriateness of social value

Phenotypic and genetic analyses of a short measure of psychosis-proneness in a large-scale Australian twin study

Previous genetic analyses of psychosis proneness have been limited by their small sample size. For the purposes of large-scale screening, a 12-item questionnaire was developed through a two-stage process of reduction from the full Chapman and Chapman scales. 3685 individuals (including 1438 complete twin pairs) aged 18–25 years and enrolled in the volunteer Australian Twin Registry returned a mail questionnaire which included this psychosis proneness scale and the Eysenck Personality Questionnaire. Despite the brevity of the questionnaire, item and factor analysis identified four unambiguous and essentially uncorrelated scales. There were (1) Perceptual Aberration – Magical Ideation; (2) Hypomania – Impulsivity/Nonconformity; (3) Social Anhedonia and (4) Physical Anhedonia. Model-fitting analyses showed additive genetic and specific environmental factors were sufficient for three of the four scales, with the Social Anhedonia scale requiring also a parameter for genetic dominance. There was no evidence for the previously hypothesised sex differences in the genetic determination of psychosis-proneness. The potential value of multivariate genetic analysis to examine the relationship between these four scales and dimensions of personality is discussed. The growing body of longitudinal evidence on psychosis-proneness suggests the value of incorporating this brief measure into developmental twin studies.

Phylogenetic relationships of Trypanosoma chelodina and Trypanosoma binneyi from Australian tortoises and platypuses inferred from small subunit rRNA analyses

Trypanosome infections are often difficult to detect by conventional microscopy and their pleomorphy often confounds differential diagnosis. Molecular techniques are now being used to diagnose infections and to determine phylogenetic relationships between species. Complete small subunit rRNA gene sequences were determined for isolates of Trypanosoma chelodina from the Brisbane River tortoise (Emydura signata), the saw-shelled tortoise (Elseya latisternum), and the eastern snake-necked tortoise (Chelodina longicollis) from southeast Queensland, Australia. Partial sequence data were also obtained for T. binneyi from a platypus (Ornithorhynchus anatinus) from Tasmania. Phylogenetic relationships between T. chelodina, T. binneyi and other species were examined by maximum parsimony and likelihood methods. The Australian tortoise and platypus trypanosomes did not exhibit any close phylogenetic relationships with those of mammals, reptiles or amphibians, but were closely related to each other, and to fish trypanosomes. This contra-indicates their co-evolution with their vertebrate hosts but does not exclude co-evolution with different groups of invertebrate vectors, notably insects and leeches.

A study of the oxidation of two aromatic polyimide fluoropolymers containing phenylphosphine oxide by a water plasma and gamma-radiolysis in air

The oxidation of two fluorinated polyimides containing phenylphosphine oxide units, TOR-RC and TOR-RC ODPA, have been studied at 300 K for treatment by a water plasma and gamma -radiolysis in air. The changes in the O 1s/C 1s ratios obtained from x-ray photoelectron spectroscopy (XPS) analysis showed that for exposure to the water plasma the ratio increases at short exposure times and then levels to a constant value. Evidence for the formation of phosphate species was also obtained from the XPS analyses. Similar observations were made for gamma -radiolysis of the polymers in air. The polymers containing phenylphosphine oxide were found to be more resistant to oxidation in the water plasma than Kapton(R). Radiolysis of the polymers in air to high doses were also accompanied by a red shift in the visible absorption spectra.

The behaviour of phenylphosphine oxide containing polyimides in a water plasma following gamma-radiolysis

The surface oxidation of two polyimides containing fluorinated phenylphosphine oxide units, TOR-RC and TOR-RC ODPA, have been studied by (XPS) spectroscopy following gamma -radiolysis under vacuum or in air and subsequent treatment in a water plasma. The changes in the O 1s/C 1s ratios obtained from (XPS) analysis showed that on exposure to the water plasma the ratio increases and then levels to a constant value which is similar to that found for exposure to the plasma without prior gamma -radiation treatment. Evidence for the formation of phosphate species was also obtained from the (XPS) analyses. (C) 2001 Elsevier Science Ltd. All rights reserved.

Chemistry, properties, and phylogenetic implications of the methylated carrageenans from red algae of the genus Areschougia (Areschougiaceae, Gigartinales, Rhodophyta)

The three Australian-endemic species comprising the genus Aresehougia have been examined to determine the structure of their nonfibrillar wall components. The polysaccharide extracted from the most widely distributed species, A. congesta (Turner) J. Agardh, was shown by compositional analyses, Fourier transform infrared (FTIR) spectroscopy, linkage analysis, and C-13-NMR spectroscopy to be a carrageenan composed predominantly of the repeating disaccharides 6'-O-methylcarrabiose 2,4'-disulfate, carrabiose 2,4-disulfate (the repeating unit of L-carrageenan), 4',6'-O-(1-carboxyethylidene)carrabiose 2-sulfate, and 6'-O-methylcarrabiose 2-sulfate. The carrageenan also contained small amounts of 4-linked Galp residues, some bearing methyl ether substitution at O-3 and some possibly bearing sulfate ester and/or glycosyl substitutions at O-3. The A. congesta carrageenan had unique rheological properties, its gels having some similarities to those of commercial iota -carrageenan but with the viscosity of commercial lambda -carrageenan. Polysaccharides from A. ligulata Harvey ex J. Agardh and A. stuartii Harvey were shown by constituent sugar and FTIR analyses to be sulfated galactans rich in mono-O-methylgalactose. The carrageenan structures of Areschougia spp. were consistent with those of the genera Rhabdonia, Erythroclonium, and Austroclonium, the other genera constituting the family Areschougiaceae.

Active site heterogeneity in dimethyl sulfoxide reductase from Rhodobacter capsulatus revealed by raman spectroscopy

Raman spectroscopy has been used to investigate the structure of the molybdenum cofactor in DMSO reductase from Rhodobacter capsulatus. Three oxidized forms of the enzyme, designated 'redox cycled', 'as prepared', and DMSORmodD, have been studied using 752 nm laser excitation. In addition, two reduced forms of DMSO reductase, prepared either anaerobically using DMS or using dithionite, have been characterized. The 'redox cycled' form has a single band in the Mo=O stretching region at 865 cm(-1) consistent with other studies. This oxo ligand is found to be exchangeable directly with (DMSO)-O-18 or by redox cycling. Furthermore, deuteration experiments demonstrate that the oxo ligand in the oxidized enzyme has some hydroxo character, which is ascribed to a hydrogen bonding interaction with Trp 116. There is also evidence from the labeling studies for a modified dithiolene sulfur atom, which could be present as a sulfoxide. In addition to the 865 cm(-1) band, an extra band at 818 cm(-1) is observed in the Mo=O stretching region of the 'as prepared' enzyme which is not present in the 'redox cycled' enzyme. Based on the spectra of unlabeled and labeled DMS reduced enzyme, the band at 818 cm(-1) is assigned to the S=O stretch of a coordinated DMSO molecule. The DMSORmodD form, identified by its characteristic Raman spectrum, is also present in the 'as prepared' enzyme preparation but not after redox cycling. The complex mixture of forms identified in the 'as prepared' enzyme reveals a substantial degree of active site heterogeneity in DMSO reductase.

Assessing ecological impacts of shrimp and sewage effluent: Biological indicators with standard water quality analyses

Despite evidence linking shrimp farming to several cases of environmental degradation, there remains a lack of ecologically meaningful information about the impacts of effluent on receiving waters. The aim of this study was to determine the biological impact of shrimp farm effluent, and to compare and distinguish its impacts from treated sewage effluent. Analyses included standard water quality/sediment parameters, as well as biological indicators including tissue nitrogen (N) content, stable isotope ratio of nitrogen (delta N-15) and amino acid composition of inhabitant seagrasses, mangroves and macroalgae. The study area consisted of two tidal creeks, one receiving effluent from a sewage treatment plant and the other from an intensive shrimp farm. The creeks discharged into the western side of Moreton Bay, a sub-tropical coastal embayment on the east coast of Australia. Characterization of water quality revealed significant differences between the creeks, and with unimpacted eastern Moreton Bay. The sewage creek had higher concentrations of dissolved nutrients (predominantly NO3-/NO2- and PO43-, compared to NH4+ in the shrimp creek). In contrast, the shrimp creek was more turbid and had higher phytoplankton productivity. Beyond 750 m from the creek mouths, water quality parameters were indistinguishable from eastern Moreton Bay values. Biological indicators detected significant impacts up to 4 km beyond the creek mouths (reference site). Elevated plant delta N-15 values ranged from 10.4-19.6 parts per thousand at the site of sewage discharge to 2.9-4.5 parts per thousand at the reference site. The free amino acid concentration and composition of seagrass and macroalgae was used to distinguish between the uptake of sewage and shrimp derived N. Proline (seagrass) and serine (macroalgae) were high in sewage impacted plants and glutamine (seagrass) and alanine (macroalgae) were high in plants impacted by shrimp effluent. The delta N-15 isotopic signatures and free amino acid composition of inhabitant flora indicated that sewage N extended further from the creek mouths than shrimp N. The combination of physical/chemical and biological indicators used in this study was effective in distinguishing the composition and subsequent impacts of aquaculture and sewage effluent on the receiving waters. (C) 2001 Academic Press.

2,6,,9-trioxabicyclo[3.3.1]nona-3,7-dienes and 2,4,6,8-tetraoxaadamantanes: Novel chiral spacer units in macrocyclic polyethers

The unusual chiral heterocyclic systems, trioxabicyclo[3.3.1]nona-3,7-dienes (bridged bisdioxines), are incorporated as novel spacer molecules into macrocyclic polyether ring systems of various sizes (8, 9 as well as 11-15) by cyclocondensation reaction of the! bisacid chloride 4b or bisesters 6,7 and 10, with several ethylene glycols. The 2:2 macrocycles 12-14 are obtained in approximately 50:50 mixtures of diastereomers. These conclusions are mainly based on HPLC data presented in Table I as well as X-ray analyses of (1R,5R)-8c (space group Pbca, a = 10.163(3) Angstrom, b = 18.999(4) Angstrom, c = 36.187(10) Angstrom, V = 6987(3) Angstrom(3), Z = 8, d(calc) = 1.218 g cm(-3), 6974 reflections, R = 0.0553.), mesolrac-11 (space group P (1) over bar, a = 10.472(5) Angstrom, b = 16.390(5) Angstrom, c = 17.211(5) Angstrom, alpha = 98.69(2)degrees, beta = 93.04(2)degrees, gamma = 98.52(2)degrees, V = 2879.3(18) Angstrom(3), Z = 2, d(calc) = 1.173 g cm(-3), 11,162 reflections, R = 0.0945) and meso-12 (space group P2(1)/c, a = 9.927(2), b = 18.166(3), c = 17.820(3) Angstrom, beta = 96.590(10)degrees, V = 3192.3(10)Angstrom(3), Z = 4, D-c = 1.109 g cm(-3), 3490 reflections, R = 0.0646). The 1:1 macrocycles 8b,c are also formed by intramolecular transesterification of the open-chain bisesters 7b,c and their formation is favored by the use of metal ions as templates. The bridged bisdioxine moieties in 8b and 12 are converted into the corresponding chiral tetra-oxaadamantane spacers to afford macrocycles 16 and 17. Preliminary metal ion complexation studies with selected species (8c, 11-14) were also performed.

The radiation chemistry of ultem at 77 K as revealed by ESR spectroscopy

Radical formation in ultem following gamma-radiolysis has been reassessed, and the G(R*) values at different temperatures have been determined by ESR spectroscopy. The radical assignment and radical reactivity have been re-examined by photobleaching and thermal annealing studies. Photobleachable radical anions were found to comprise approximate to40% of the total number of radicals formed on radiolysis at 77 K. Spectral subtraction methods, ESR spectral simulations, measurement of g-values and the hyperfine splitting constants were used to identify the other radical intermediates. The principal chain scission radicals are formed due to scission of the main-chain at (i) the ether linkage, (ii) the isopropylidene group and (iii) the imide ring in the main chain. The side chain methyl groups of the isopropylidine units also lose hydrogen to form methylene radicals. The five-line spectrum observed to decay in the temperature range 370-430 K, which has not been assigned previously, has been identified as being characteristic of a di-substituted benzyl radical. (C) 2002 Elsevier Science Ltd. All rights reserved.