Performance of a substratum-irradiated photosynthetic biofilm reactor for the removal of sulfide from wastewater

The performance of a sulfide-removal system based on biofilms dominated by green sulfur bacteria (GSB) has been investigated. The system was supplied with radiant energy in the band 720-780 nm, and fed with a synthetic wastewater. The areal net sulfide removal rate and the efficacy of the incident radiant energy for sulfide removal have been characterized over ranges of bulk sulfide concentration (1.6-11.5 mg L-1) and incident irradiance (0.21-1.51 W m(-2)). The areal net sulfide removal rate increased monotonically with both increasing incident irradiance and increasing bulk sulfide concentration. The efficacy of the radiant energy for sulfide removal (the amount of sulfide removed per unit radiant energy supplied) also increased monotonically with rising bulk sulfide concentration, but exhibited a maximum value with respect to incident irradiance. The maximum observed values of this net removal rate and this efficacy were, respectively, 2.08 g m(-2) d(-1) and 2.04 g W-1 d(-1). In-band changes in the spectral composition of the radiant energy affected this efficacy only slightly. The products of sulfide removal were sulfate and elemental-S. The elemental-S was scarcely released into the liquid, however, and reasons for this, such as sulfur reduction and polysulfide formation, are considered. Between 1.45 and 3.85 photons were needed for the net removal of one electron from S-species. Intact samples of the biofilm were characterized by microscopy, and their thicknesses lay between 39 +/- 9 and 429 +/- 57 mum. The use of the experimentally determined rates and efficacies for the design of a pilot-scale system is illustrated. (C) 2004 Wiley Periodicals, Inc.

Human tartrate-resistant acid phosphatase becomes an effective ATPase upon proteolytic activation

Proteolytic, cleavage in an exposed loop of human tartrate-resistant acid phosphatase (TRAcP) with trypsin leads to a significant increase in activity. At each pH value between 3.25 and 8.0 the cleaved enzyme is more active. Substrate specificity is also influenced by proteolysis. Only the cleaved form is able to hydrolyze unactivated substrates efficiently, and at pH > 6 cleaved TRAcP acquires a marked preference for ATP. The cleaved enzyme also has altered sensitivity to inhibitors. Interestingly, the magnitude and mode of inhibition by fluoride depends not only on the proteolytic state but also pH. The combined kinetic data imply a role of the loop residue D158 in catalysis in the cleaved enzyme. Notably, at low pH this residue may act as a proton donor for the leaving group. In this respect the mechanism of cleaved TRAcP resembles that of sweet potato purple acid phosphatase. (c) 2005 Elsevier Inc. Ail rights reserved.

Anomalous scattering analysis of Agrobacterium radiobacter phosphotriesterase: the prominent role of iron in the heterobinuclear active site

Bacterial phosphotriesterases are binuclear metalloproteins for which the catalytic mechanism has been studied with a variety of techniques, principally using active sites reconstituted in vitro from apoenzymes. Here, atomic absorption spectroscopy and anomalous X-ray scattering have been used to determine the identity of the metals incorporated into the active site in vivo. We have recombinantly expressed the phosphotriesterase from Agrobacterium radiobacter (OpdA) in Escherichia coli grown in medium supplemented with 1 mM CoCl2 and in unsupplemented medium. Anomalous scattering data, collected from a single crystal at the Fe-K, Co-K and Zn-K edges, indicate that iron and cobalt are the primary constituents of the two metal-binding sites in the catalytic centre (alpha and P) in the protein expressed in E. coli grown in supplemented medium. Comparison with OpdA expressed in unsupplemented medium demonstrates that the cobalt present in the supplemented medium replaced zinc at the beta-position of the active site, which results in an increase in the catalytic efficiency of the enzyme. These results suggest an essential role for iron in the catalytic mechanism of bacterial phosphotriesterases, and that these phosphotriesterases are natively heterobinuclear iron-zinc enzymes.

Between-tree variation in fruit quality and fruit mineral concentrations of Hass avocados

Inconsistent internal fruit quality in Hass avocados affects consumer confidence. To determine the influence of individual trees on fruit quality, Hass avocado fruit were harvested from adjacent trees of similar external appearance in 3 commercial orchards in 1998 and 1 orchard in 1999. The trees in each orchard were grown with similar commercial practices and in similar soil types. Within each location, there were significant (P < 0.05) differences in the mean ripe fruit quality between trees with respect to fruit body rot severity ( mainly anthracnose) with and without cold storage, internal disorders severity due to diffuse discolouration and vascular browning ( after cold storage), days to ripen, percentage dry matter, and the percentage of the skin area with purple-black colour when ripe. These effects were also noted in the same orchard in 1999. There were significant (P < 0.05) differences in fruit flesh calcium, magnesium, potassium, boron and zinc concentrations between trees. Significant (P < 0.05) correlations were observed between average fruit mineral concentrations in each tree ( particularly calcium, magnesium and potassium) and body rot severity, percentage dry matter and fruit mass. There was little conclusive evidence that characteristics such as the growth of the non-suberised roots or the degree of scion under- or overgrowth was involved in these tree effects; however, differences between trees with respect to other rootstock characteristics may be involved. The inconsistency of the correlations across sites and years suggested that other factors apart from tree influences could also affect the relationship between fruit minerals and fruit quality.

Effects of postharvest methyl jasmonate treatments against Botrytis cinerea on Geraldton waxflower (Chamelaucium uncinatum)

Cut Geraldton waxflower (Chamelaucium uncinatum Schauer) flowers are often infected with Botrytis cinerea. Release of infection from quiescence can cause ethylene production by invaded host tissues and result in flower abscission. Postharvest floral organ abscission is a major problem for the commercial waxflower industry. Methyl jasmonate (MeJA) occurs naturally in plant tissue and has a signalling role in eliciting induced systemic resistance against disease. MeJA treatments have been shown to suppress B. cinerea infecting cut rose flowers. The present experiments investigated the potential of exogenous MeJA treatments for B. cinerea management on harvested waxflower. MeJA treatments of 10 and 100 L liquid MeJA/L of air applied to cv. Purple Pride and 1 L MeJA/L to cv. Mullering Brook gave reductions in disease severity for uninoculated stems. However, concentrations of 100 L MeJA/L applied to Purple Pride in addition to 1 and 10 L MeJA/L applied to Mullering Brook increased the incidence of floral organ fall. Flower abscission upon treatment with MeJA may be due to induced systemic resistance-associated upregulation of ethylene biosynthesis. MeJA treatments had no direct effect on B. cinerea hyphal elongation in vitro. Collectively, these results show that while MeJA treatment may elicit defence in waxflower against Botrytis, the chemical also causes floral organ fall. Thus, exogenous MeJA treatments do not have potential for B. cinerea management on harvested waxflower.

Iron (Fe) bioavailability and the distribution of anti-Fe nutrition biochemicals in the unpolished, and bran fraction of five rice gei polished grain riotypes

Iron (Fe) bioavailability in unpolished, polished grain and bran fraction of five rice genotypes with a range of Fe contents was measured by in vitro digestion and cultured Caco-2 cells of cooked grain. There was a significant difference in Fe bioavailability among the five rice genotypes tested, in both the unpolished and polished grain. The range of Fe bioavailability variation in polished rice was much wider than that of unpolished, suggesting the importance of using Fe levels and bioavailability in polished rice grain as the basis for selecting high-Fe rice cultivars for both agronomic and breeding purposes. Milling and polishing the grain to produce polished (or white) rice increased Fe bioavailability in all genotypes. Iron bioavailability in polished rice was high in the UBON2 and Nishiki, intermediate in both IR68144 and KDML105, and low in CMU122. All genotypes had low bioavailability of Fe in bran fraction compared to unpolished and polished grain, except in CMU122. CMU122 contained the lowest level of bioavailable Fe in unpolished and polished grain and bran, because of the dark purple pericarp colored grain and associated tannin content. The level of bioavailable Fe was not significantly correlated with grain Fe concentration or grain phytate levels among these five genotypes tested. The negative relationship between Fe bioavailability and the levels of total extractable phenol was only observed in unpolished (r = -0.83**) and bran fraction (r = -0.50*). The present results suggested that total extractable phenol and tannin contents could also contribute to lowering bioavailability of Fe in rice grain, in addition to phytate. (c) 2006 Society of Chemical Industry

Lasers - An effective artificial source of radiation for the cultivation of anoxygenic photosynthetic bacteria

The laser diode (LD) is a unique light source that can efficiently produce all radiant energy within the narrow wavelength range used most effectively by a photosynthetic microorganism. We have investigated the use of a single type of LID for the cultivation of the well-studied anoxygenic photosynthetic bacterium, Rhodobacter capsulatus (Rb. capsulatus). An array of vertical-cavity surface-emitting lasers (VCSELs) was driven with a current of 25 mA, and delivered radiation at 860 nm with 0.4 nm linewidth. The emitted light was found to be a suitable source of radiant energy for the cultivation of Rb. capsulatus. The dependence of growth rate on incident irradiance was quantified. Despite the unusual nearly monochromatic light source used in these experiments, no significant changes in the pigment composition and in the distribution of bacteriochlorophyll between LHII and LHI-RC were detected in bacterial cells transferred from incandescent light to laser light. We were also able to show that to achieve a given growth rate in a light-limited culture, the VCSEL required only 30% of the electricity needed by an incandescent bulb, which is of great significance for the potential use of laser-devices in biotechnological applications and photobioreactor construction. (c) 2006 Wiley Periodicals, Inc.

Cue salience in multiple cue attentional capture

The predominant use of single element cues in visual attentional capture research motivated examination using dual capture cues. Participants in these studies viewed computer screens briefly displaying sequences of feature-defined positional cues and targets, with target identification response time recorded. Five initial experiments utilising the features of colour (purple) and intensity (bold font), and reported at EPC 2005, revealed contingent capture influences and suggested capture by colour cues may be more powerful than single cue literature has indicated. Three follow-up experiments manipulated displays and defining features to see if the conclusions remained. Experiments 6 and 7 investigated whether target identification in the initial series was based on a featural or singleton search. Experiment 8 then tested "onset' versus "purple" under the condition of specific attentional set, a featural change that appeared to remove purple colour dominance evidenced in the initial experimental series. Overall, outcomes of both experimental series suggest strong salience involvement with overtones of contingent capture for specific featural selections. The novel multi-cue approach revealed the significance of relative salience within these selections.

The EU's 'transnational power over' Central Asia:Developing and applying a structurally integrative approach to the study of the EU's power over Central Asia

This thesis challenges the consensual scholarly expectation of low EU impact in Central Asia. In particular, it claims that by focusing predominantly on narrow, micro-level factors, the prevailing theoretical perspectives risk overlooking less obvious aspects of the EU?s power, including structural aspects, and thus tend to underestimate the EU?s leverage in the region. Therefore, the thesis argues that a more structurally integrative and holistic approach is needed to understand the EU?s power in the region. In responding to this need, the thesis introduces a conceptual tool, which it terms „transnational power over? (TNPO). Inspired by debates in IPE, in particular new realist and critical IPE perspectives, and combining these views with insights from neorealist, neo-institutionalist and constructivist approaches to EU external relations, the concept of TNPO is an analytically eclectic notion, which helps to assess the degree to which, in today?s globalised and interdependent world, the EU?s power over third countries derives from its control over a combination of material, institutional and ideational structures, making it difficult for the EU?s partners to resist the EU?s initiatives or to reject its offers. In order to trace and assess the mechanisms of EU impact across these three structures, the thesis constructs a toolbox, which centres on four analytical distinctions: (i) EU-driven versus domestically driven mechanisms, (ii) mechanisms based on rationalist logics of action versus mechanisms following constructivist logics of action, (iii) agent-based versus purely structural mechanisms of TNPO, and (iv) transnational and intergovernmental mechanisms of EU impact. Using qualitative research methodology, the thesis then applies the conceptual model to the case of EU-Central Asia. It finds that the EU?s power over Central Asia effectively derives from its control over a combination of material, institutional and ideational structures, including its position as a leader in trade and investment in the region, its (geo)strategic and security-related capabilities vis-à-vis Central Asia, as well as the relatively dense level of institutionalisation of its relations with the five countries and the positive image of the EU in Central Asia as a more neutral actor.

The effects of coloured light filter overlays on reading rates in age-related macular degeneration

Purpose: To determine the effect of coloured light filter overlays on reading rates for people with age-related macular degeneration (AMD). Method: Using a prospective clinical trial design, we examined the null hypothesis that coloured light filter overlays do not improve reading rates in AMD when compared to a clear filter. Reading rates for 12 subjects with non-exudative AMD, associated with a relative scotoma and central fixation (mean age 81 years, SD 5.07 years) were determined using the Rate of Reading Test® (printed, nonsense, lower case sans serif, stationary text) with 10 different, coloured light filter overlays (Intuitive Overlays®; figures in brackets are percentage transmission values); rose (78%), pink (78%), purple (67%), aqua (81%), blue (74%), lime-green (86%), mint-green (85%), yellow (93%), orange (83%) and grey (71%). A clear overlay (Roscolene # 00) (360 cdm-2) with 100% transmittance was used as a control. Results: ANOVA indicated that there was no statistically significant difference in reading rates with the coloured light filter overlays compared to the clear filter. Furthermore, chi-squared analysis indicated that the rose, purple and blue filters had a significantly poorer overall ranking in terms of reading rates compared to the other coloured and clear light filters. Conclusion: Coloured light filter overlays are unlikely to provide a clinically significant improvement in reading rates for people with non-exudative AMD associated with a relative scotoma and central fixation. Copyright © Acta Ophthalmol Scand 2004.

High-activity, single-site mesoporous Pd/Al2O3 catalysts for selective aerobic oxidation of allylic alcohols

Pd does it alone : Tailored heterogeneous catalysts offer exciting, alternative, clean technologies for regioselective molecular transformations. A mesoporous alumina support stabilizes atomically dispersed PdII surface sites (see picture, C light gray, O red, Pd dark gray, Al purple, H white), thereby dramatically enhancing catalytic performance in the aerobic selective oxidation of alcohols.

Onions:a global benefit to health

Onion (Allium cepa L.) is botanically included in the Liliaceae and species are found across a wide range of latitudes and altitudes in Europe, Asia, N. America and Africa. World onion production has increased by at least 25% over the past 10 years with current production being around 44 million tonnes making it the second most important horticultural crop after tomatoes. Because of their storage characteristics and durability for shipping, onions have always been traded more widely than most vegetables. Onions are versatile and are often used as an ingredient in many dishes and are accepted by almost all traditions and cultures. Onion consumption is increasing significantly, particularly in the USA and this is partly because of heavy promotion that links flavour and health. Onions are rich in two chemical groups that have perceived benefits to human health. These are the flavonoids and the alk(en)yl cysteine sulphoxides (ACSOs). Two flavonoid subgroups are found in onion, the anthocyanins, which impart a red/purple colour to some varieties and flavanols such as quercetin and its derivatives responsible for the yellow and brown skins of many other varieties. The ACSOs are the flavour precursors, which, when cleaved by the enzyme alliinase, generate the characteristic odour and taste of onion. The downstream products are a complex mixture of compounds which include thiosulphinates, thiosulphonates, mono-, di- and tri-sulphides. Compounds from onion have been reported to have a range of health benefits which include anticarcinogenic properties, antiplatelet activity, antithrombotic activity, antiasthmatic and antibiotic effects. Here we review the agronomy of the onion crop, the biochemistry of the health compounds and report on recent clinical data obtained using extracts from this species. Where appropriate we have compared the data with that obtained from garlic (Allium sativum L.) for which more information is widely available. Copyright © 2002 John Wiley & Sons, Ltd.

Attitudes to language in literary sources:beyond post-colonialism in nigerian literature

All societies display attitudes to (varieties of) languages that tell us about the relative status of the groups that are associated to them. One method to document these is the systematic study of public discourses, including literary production. How (varieties of) languages are used, mentioned and characterised in a literary work tells us about their social status, and any change in this status should therefore be followed by changes in judgements on languages. This is demonstrated by the present paper with reference to the language attitudes in Nigeria, on the basis of two iconic Nigerian novels 2004 Purple Hibiscus and in 1958 classic postcolonial Things Fall Apart, separated by nearly fifty years. Ibo as well as Pidgin, Nigerian and European Englishes are presented in Purple Hibiscus in nuanced complementary configurations. A strong axiological polarisation is by contrast offered in Things Fall Apart between Ibo speakers and Ibo interpreters who are presented as cruel and ridiculous traitors siding with the English colonising power whose language, curiously, is not commented upon. Showing how a replicable method applied to language judgements can document social organisation and change, these results validate the view that the Nigerian society and culture has moved beyond the historically situated postcolonialist movement to embrace a globalised paradigm. © 2010 Taylor & Francis.