Functionalization of carbon nanotubes using aminobenzene acids and electrochemical methods. Electroactivity for the oxygen reduction reaction

Functionalized carbon nanotubes (CNTs) using three aminobenzene acids with different functional groups (carboxylic, sulphonic, phosphonic) in para position have been synthesized through potentiodynamic treatment in acid media under oxidative conditions. A noticeable increase in the capacitance for the functionalized carbon nanotubes mainly due to redox processes points out the formation of an electroactive polymer thin film on the CNTs surface along with covalently bonded functionalities. The CNTs functionalized using aminobenzoic acid rendered the highest capacitance values and surface nitrogen content, while the presence of sulfur and/or phosphorus groups in the aminobenzene structure yielded a lower functionalization degree. The oxygen reduction reaction (ORR) activity of the functionalized samples was similar to that of the parent CNTs, independently of the functional group present in the aminobenzene acid. Interestingly, a heat treatment in N2 atmosphere with a very low O2 concentration (3125 ppm) at 800 °C of the CNTs functionalized with aminobenzoic acid produced a material with high amounts of surface oxygen and nitrogen groups (12 and 4% at., respectively), that seem to modulate the electron-donor properties of the resulting material. The onset potential and limiting current for ORR was enhanced for this material. These are promising results that validates the use of electrochemistry for the synthesis of novel N-doped electrocatalysts for ORR in combination with adequate heat treatments.

Ecological restoration across the Mediterranean Basin as viewed by practitioners

Restoration efforts in the Mediterranean Basin have been changing from a silvicultural to an ecological restoration approach. Yet, to what extent the projects are guided by ecological restoration principles remains largely unknown. To analyse this issue, we built an on-line survey addressed to restoration practitioners. We analysed 36 restoration projects, mostly from drylands (86%). The projects used mainly soil from local sources. The need to comply with legislation was more important as a restoration motive for European Union (EU) than for non-EU countries, while public opinion and health had a greater importance in the latter. Non-EU countries relied more on non-native plant species than EU countries, thus deviating from ecological restoration guidelines. Nursery-grown plants used were mostly of local or regional provenance, whilst seeds were mostly of national provenance. Unexpected restoration results (e.g. inadequate biodiversity) were reported for 50% of the projects and restoration success was never evaluated in 22%. Long term evaluation (> 6 years) was only performed in 31% of cases, and based primarily on plant diversity and cover. The use of non-native species and species of exogenous provenances may: i) entail the loss of local genetic and functional trait diversity, critical to cope with drought, particularly under the predicted climate change scenarios, and ii) lead to unexpected competition with native species and/or negatively impact local biotic interactions. Absent or inappropriate monitoring may prevent the understanding of restoration trajectories, precluding adaptive management strategies, often crucial to create functional ecosystems able to provide ecosystem services. The overview of ecological restoration projects in the Mediterranean Basin revealed high variability among practices and highlighted the need for improved scientific assistance and information exchange, greater use of native species of local provenance, and more long-term monitoring and evaluation, including functional and ecosystem services' indicators, to improve and spread the practice of ecological restoration.

Consequences of feeling dissimilar from others in a work team

This study extended the current literature on group diversity by examining the moderating influence of perceived group openness to diversity on the relationships between perceived individual visible, informational, and value dissimilarity; individual task and relationship conflict; and work group involvement. A survey was administered to 129 public service employees who worked in intact teams. Results revealed that value dissimilarity had a positive association with task and relationship conflict and a negative association with work group involvement. Perceived group openness to diversity moderated the associations between visible and informational dissimilarity and work group involvement, and between value dissimilarity and task conflict. These results highlight the importance of managing differences by introducing norms promoting diversity and the involvement of all team members.

Biosynthetic pathways to dichloroimines; precursor incorporation studies on terpene metabolites in the tropical marine sponge Stylotella aurantium

The biosynthetic origin of the dichloroimine functional group in the marine sponge terpene metabolites stylotellanes A ( 3) and B ( 4) was probed by the use of [C-14]-labelled precursor experiments. Incubation of the sponge Stylotella aurantium with [C-14]-labelled cyanide or thiocyanate resulted in radioactive terpenes in which the radiolabel was shown by hydrolytic chemical degradation to be associated specifically with the dichloroimine carbons. Additionally, label from both precursors was incorporated into farnesyl isothiocyanate ( 2). A time course experiment with [ 14C]cyanide revealed that the specific activity for farnesyl isothiocyanate decreases over time, but increases for stylotellane B ( 4), consistent with the rapid formation of farnesyl isothiocyanate ( 2) from inorganic precursors followed by a slower conversion to stylotellane B ( 4). The advanced precursors farnesyl isothiocyanate ( 2) and farnesyl isocyanide ( 5) were supplied to S. aurantium, and shown to be incorporated efficiently into stylotellane A ( 3) and B ( 4). Feeding of [C-14]-farnesyl isothiocyanate ( 2) resulted in a higher incorporation of label than with [C-14]-farnesyl isocyanide ( 5). Farnesyl isocyanide was incorporated into farnesyl isothiocyanate in agreement with labelling studies in other marine sponges. Both farnesyl isocyanide and isothiocyanate were further incorporated into axinyssamide A ( 11) as well as the cyclized dichloroimines (12)-(14), ( 16) that represent more advanced biosynthetic products of this pathway. These results identify the likely biosynthetic pathway leading to the major metabolites of S. aurantium.

Molecular recognition of sub-micromolar inhibitors by the epinephrine-synthesizing enzyme phenylethanolamine N-methyltransferase

The crystal structures of human phenylethanolamine N-methyltransferase in complex with S-adenosyl-L-homocysteine (7, AdoHcy) and either 7-iodo-1,2,3,4-tetrahydroisoquinoline (2) or 8,9-dichloro-2,3,4,5-tetrahydro-1H-2-benzazepine (3, LY134046) were determined and compared with the structure of the enzyme complex with 7 and 7-aminosulfonyl-1,2,3,4-tetrahydroisoquinoline (1, SK&F 29661). The enzyme is able to accommodate a variety of chemically disparate functional groups on the aromatic ring of the inhibitors through adaptation of the binding pocket for this substituent and by subtle adjustments of the orientation of the inhibitors within the relatively planar binding site. In addition, the interactions formed by the amine nitrogen of all three inhibitors reinforce the hypothesis that this functional group mimics the beta-hydroxyl of norepinephrine rather than the amine. These studies provide further clues for the development of improved inhibitors for use as pharmacological probes.

Research on the BET surface area and packing of molecules on the activated carbon

Adsorption of different aromatic compounds (two of them are electrolytes) onto an untreated activated carbon (F100) is investigated. The experimental isotherms are fitted into Langmuir homogenous and heterogeneous Model. Theoretical maximum adsorption capacities that are based on the BET surface area of the adsorbent cannot be close to the real value. The affinity and the heterogeneity of the adsorption system observed to be related to the pK(a) of the solutes. The maximum adsorption capacity (Q(max)) of activated carbon for each solute dependent on the molecular area as well as the type of functional group attached on the aromatic compound and also pH of solution. The arrangement of the molecules on the carbon surface is not face down. Furthermore, it is illustrated that the packing arrangement is most likely edge to face (sorbate-sorbent) with various tilt angles. For characterization of the carbon, the N-2 and CO2 adsorption were used. X-ray Photoelectron Spectroscopy (XPS) measurement was used to surface elemental analysis of activated carbon.

Investigating direct routes to an advanced intermediate for the synthesis of C-20 diterpene alkaloids

Rapid access to the ABCE ring system of the C-20 diterpene alkaloids was achieved by silver (I) promoted intramolecular Friedel-Crafts arylation of a functional group specific 5-bromo-3-azabicyclo[3.3.1]nonane derivative. (c) 2005 Elsevier Ltd. All rights reserved.

Screening, characterization and flocculating property of carbohydrate polymer from newly isolated Enterobacter cloacae WD7

A total of 188 carbohydrate polymer-producing bacterial strains were isolated from recycled sludge of five seafood processing plants. Among three selected isolates, identified as Enterobacter cloacae WD7, Enterobacter agglomerans WD50 and Pseudomonas alcaligenes WD22. E. cloacae WD7 generated a viscous culture broth exhibiting the highest flocculating activity and a crude polymer yield of 2.27 g/L after 3 days cultivation. Partial purification of this polymer was performed by precipitation with 95% ethanol, dialysis and freeze-drying. It was characterized as an acidic heteropolysaccharide, composed of neutral sugars (29.4%), uronic acids (14.2%) and amino sugars (0.93%). The functional group analysis by FT-IR spectroscopy showed the presence of hydroxyl, carboxyl, carbonyl and methoxyl groups. Thermal analysis by DSC showed the crystalline transition and the crystalline melting point (T-m) at 300 degrees C. This polysaccharide was soluble in water and insoluble in any organic solvents tested; gelation occurred under alkaline conditions in the presence of divalent cations in which copper as CuSO4 gave the best result. Studies on the flocculation property revealed that this polysaccharide was stable at 4-60 degrees C and pH 5-7. The optimal concentrations for the flocculating activity were 2 mg/L polysaccharide and 40 mM CaCl2 which played the synergistic effect on kaolin flocculation. Moreover, this polysaccharide could flocculate the kaolin suspension over a wide range of pH (pH 2-8) and temperature (4-50 degrees C) tested in the presence of CaCl2. (c) 2006 Elsevier Ltd. All rights reserved.

The role of team identification in the dissimilarity-conflict relationship

This study examined the role of team identification in the dissimilarity and conflict relationship. We tested competing predictions that team identification would either mediate or moderate the positive associations between visible (age, gender and ethnic background), professional (background) and value dissimilarity and task and relationship conflict. Data was collected from 27 MBA student teams twice during a semester. Multilevel modelling and a longitudinal design were used. Results showed that value dissimilarity was positively associated with task and relationship conflict at Time 2. Its effects on relationship conflict at Time 1 were moderated by team identification. Team identification also moderated the effects of gender, age and ethnic dissimilarity on task conflict at Time 2, and the effects of gender and professional dissimilarity on relationship conflict at Time 2. No support was obtained for the mediating role of team identification on the associations between dissimilarity and conflict, or for changes in the effects of dissimilarity over time.

Synthesis and cytotoxity of oxysterols:studies on the A,B ring polyoxygenated sterols

Oxysterols (OS), the polyoxygenated sterols, represent a class of potent regulatory molecules for important biological actions. Cytotoxicity of OS is one of the most important aspects in studies of OS bioactivities. However, studies, the structure-activity relationship (SAR) study in particular, have been hampered by the limited availability of structurally diverse OS in numbers and amounts. The aim of this project was to develop robust synthetic methods for the preparation of polyhydroxyl sterols, thereof, evaluate their cytotoxicity and establish structure-activity relationship. First, we found hydrophobicity of the side chain is essential for 7-HC's cytotoxicity, and a limited number of hydroxyl groups and a desired configuration on the A, B ring are required for a potent cytotoxicity of an OS, after syntheses and tests of a number of 7-HC's analogues against cancer cell lines. Then polyoxygenation of cholesterol A, B rings was explored. A preparative method for the synthesis of four diastereomerically pure cholest-4-en-3,6-diols was developed. Epoxidation on these cholest-4-en-3,6-diols showed that an allyl group exerts an auxiliary role in producing products with desired configuration in syntheses of the eight diastereomerically pure 45-epoxycholestane-3,6-diols. Reduction of the eight 45-epoxycholestane-3,6-diols produced all eight isomers of the cytotoxic 5α-acholestane 3β,5,6β-triol (CT) for the first time. Epoxide ring opening with protic or Lewis acids on the eight 45-epoxycholestane-3,6-diols are carefully studied. The results demonstrated a combination of an acid and a solvent affected the outcomes of a reaction dramatically. Acyl group participation and migration play an important role with numbers of substrates under certain conditions. All the eight 4,5-trans cholestane- 3,4,5,6-tetrols were synthesised through manipulation of acyl participation. Furthermore these reaction conditions were tested when a number of cholestane-3,4, 5,6,7-pentols and other C3-C7 oxygenated sterols were synthesised for the first time. Introduction of an oxygenated functional group through cholest-2-ene derivatives was studied. The elimination of 3-(4-toluenesulfonate) esters showed the interaction between the existing hydroxyls or acyls with the reaction centre often resulted in different products. The allyl oxidation, epoxidation and Epoxide ring opening reactions are investigated with these cholest-2-enes.

Solubility enhancement of poorly water soluble drugs using liposome technology

The aim of this work is to investigate the various parameters that could control the encapsulation of lipophilic drugs and investigate the influence of the physical properties of poorly water-soluble drugs on bilayer loading. Initial work investigated on the solubilisation of ibuprofen, a model insoluble drug. Drug loading was assessed using HPLC and UV spectrophotometric analysis. Preliminary studies focused on the influence of bilayer composition on drug loading to obtain an optimum cholesterol concentration. This was followed up by studies investigating the effect of longer alkyl chain lipids, unsaturated alkyl chain lipids and charged lipids. The studies also focused on the effects of pH of the hydration medium and addition of the single chain surfactant a-tocopherol. The work was followed up by investigation of a range of insoluble drugs including flurbiprofen, indomethacin, sulindac, mefenamic acid, lignocaine and progesterone to investigate the influence of drugs properties and functional group on liposomal loading. The results show that no defined trend could be obtained linking the drug loading to the different drug properties including molecular weight, log P and other drug specific characteristics. However, the presence of the oppositely charged lipids improved the encapsulation of all the drugs investigated with a similar effect obtained with the substitution of the longer chain lipids. The addition of the single chain surfactant a-tocopherol resulted in enhancement of drug loading and possibly is governed by the log P of the drug candidate. Environmental scanning-electron microscopy (ESEM) was used to dynamically follow the changes in liposome morphology in real time during dehydration thereby providing a alternative assay of liposome formulation and stability. The ESEM analysis clearly demonstrated ibuprofen incorporation enhanced the stability of PC:Chol liposomes.

Mode control in multimode optical fibre and its applications

This thesis describes an investigation into methods for controlling the mode distribution in multimode optical fibres. The major contributions presented in this thesis are summarised below. Emerging standards for Gigabit Ethernet transmission over multimode optical fibre have led to a resurgence of interest in the precise control, and specification, of modal launch conditions. In particular, commercial LED and OTDR test equipment does not, in general, comply with these standards. There is therefore a need for mode control devices, which can ensure compliance with the standards. A novel device consisting of a point-load mode-scrambler in tandem with a mode-filter is described in this thesis. The device, which has been patented, may be tuned to achieve a wide range of mode distributions and has been implemented in a ruggedised package for field use. Various other techniques for mode control have been described in this work, including the use of Long Period Gratings and air-gap mode-filters. Some of the methods have been applied to other applications, such as speckle suppression and in sensor technology. A novel, self-referencing, sensor comprising two modal groups in the Mode Power Distribution has been designed and tested. The feasibility of a two-channel Mode Group Diversity Multiplexed system has been demonstrated over 985m. A test apparatus for measuring mode distribution has been designed and constructed. The apparatus consists of a purpose-built video microscope, and comprehensive control and analysis software written in Visual Basic. The system may be fitted with a Silicon camera or an InGaAs camera, for measurement in the 850nm and 130nm transmission windows respectively. A limitation of the measurement method, when applied to well-filled fibres, has been identified and an improvement to the method has been proposed, based on modelled Laguerre Gauss field solutions.

Creative self-efficacy and individual creativity in teams:cross-level interactions with team informational resources

We propose a cross-level perspective on the relation between creative self-efficacy and individual creativity in which team informational resources, comprising both shared “knowledge of who knows what” (KWKW) and functional background diversity, benefit the creativity of individuals more with higher creative self-efficacy. To test our hypotheses, we conducted a multi-level study with 176 employees working in 34 research and development teams of a multinational company in 4 countries. In support of our hypotheses, the link between creative self-efficacy and individual creativity was more positive with greater shared KWKW, and this interactive effect was pronounced for teams of high rather than low functional background diversity. We discuss implications for the study of creative self-efficacy in team contexts. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

Thermal stability of sewage sludge pyrolysis oil

The stability of the oil phase obtained from intermediate pyrolysis process was used for this investigation. The analysis was based on standard methods of determining kinematic viscosity, gas - chromatography / mass - spectrometry for compositional changes, FT-IR for functional group, Karl Fischer titration for water content and bomb calorimeter for higher heaating values. The methods were used to determine changes that occurred during ageing. The temperatures used for thermal testing were 60 °C and 80 °C for the periods of 72 and 168 h. Methanol and biodiesel were used as solvents for the analysis. The bio-oil samples contained 10 % methanol, 10 % Biodiesel, 20 % Biodiesel and unstabilised pyrolysis oil. The tests carried out at 80 °C showed drastic changes compared to those at 60 °C. The bio-oil samples containing 20 % biodiesel proved to be more stable than those with 10 % methanol. The unstabilised pyrolysis oil showed the greatest changes in viscosity, composition change and highest increase in water content. The measurement of kinematic viscosity and gas chromatograph mass spectrometry were found to be more reliable for predicting the ageing process.

Fish population dynamics in a seasonally varying wetland

Small fishes in seasonally flooded environments such as the Everglades are capable of spreading into newly flooded areas and building up substantial biomass. Passive drift cannot account for the rapidity of observed population expansions. To test the ‘reaction–diffusion’ mechanism for spread of the fish, we estimated their diffusion coefficient and applied a reaction–diffusion model. This mechanism was also too weak to account for the spatial dynamics. Two other hypotheses were tested through modeling. The first—the ‘refuge mechanism’—hypothesizes that small remnant populations of small fishes survive the dry season in small permanent bodies of water (refugia), sites where the water level is otherwise below the surface. The second mechanism, which we call the ‘dynamic ideal free distribution mechanism’ is that consumption by the fish creates a prey density gradient and that fish taxis along this gradient can lead to rapid population expansion in space. We examined the two alternatives and concluded that although refugia may play an important role in recolonization by the fish population during reflooding, only the second, taxis in the direction of the flooding front, seems capable of matching empirical observations. This study has important implications for management of wetlands, as fish biomass is an essential support of higher trophic levels.