Methacryloxyethyl phosphate-grafted expanded polytetrafluoroethylene membranes for biomedical applications

Expanded polytetrafluoroethylene (ePTFE) membranes were modified by graft copolymerization with methacryloxyethyl phosphate (MOEP) in methanol and 2-butanone (methyl ethyl ketone (MEK)) at ambient temperature using gamma irradiation. The effect of dose rate (0.46 and 4.6 kGyh(-1)), monomer concentration (1-40 %) and solvent were studied and the modified membranes were characterized by weight increase, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). XPS was used to determine the % degree of surface coverage using the C-F (ePTFE membrane) and the C-C (MOEP graft copolymer) peaks. Grafting yield, as well as surface coverage, were found to increase with increasing monomer concentration and were significantly higher for samples grafted in MEK than in methanol solution. SEM images showed distinctly different surface morphologies for the membranes grafted in methanol (smooth) and MEK (globular), hence indicating phase separation of the homopolymer in MEK. We propose that in our system, the non-solvent properties of MEK for the homopolymer play a more important role than solvent chain transfer reactions in determining grafting outcomes. (c) 2005 Society of Chemical Industry.

Biological response of broiler chickens fed peas (Pisum sativum L.) expressing the bean (Phaseolus vulgaris L.) alpha-amylase inhibitor transgene

The nutritive value of transgenic peas expressing an a-amylase inhibitor (alpha-Ail) was evaluated with broiler chickens. The effects of feeding transgenic peas on the development of visceral organs associated with digestion and nutrient absorption were also examined. The chemical composition of the conventional and the transgenic peas used in this study were similar. In the two feeding trials, that were conducted normal and transgenic peas were incorporated into a maize-soybean diet at concentrations up to 500 g kg(-1). The diets were balanced to contain similar levels of apparent metabolisable energy (AME) and amino acids. In the first trial, the birds were fed the diets from 3 to 17days post-hatching and with levels of transgenic peas at 250 g kg(-1) or greater there was a significant reduction in body weight but an increase in feed intake resulting in deceased feed conversion efficiency. In the second trial, in which the birds were fed diets containing 300 g kg(-1) transgenic peas until 40 days of age, growth performance was significantly reduced. It was also demonstrated that the ileal starch digestibility coefficient (0.80 vs 0.42) was significantly reduced in the birds fed transgenic peas. Determination of AME and ileal digestibility of amino acids in 5-week-old broilers demonstrated a significant reduction in AME (12.12 vs 5.08 MJ kg(-1) DM) in the birds fed the transgenic peas. The AME value recorded for transgenic peas reflected the lower starch digestibility of this line. Real digestion of protein and amino acids was unaffected by treatment. Expression of a-Ail in peas did not appear to affect bird health or the utilisation of dietary protein. However, the significant reduction in ileal digestion of starch in transgenic peas does reduce the utility of this feedstuff in monogastric diets where efficient energy utilisation is required. (c) 2006 Society of Chemical Industry.

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

Total and ileal digestible tryptophan contents of feedstuffs for broiler chickens

Reliable values of total and digestible tryptophan in components of feed formulation matrices are needed because tryptophan is often the third limiting amino acid in practical poultry diets. However, tryptophan is oxidatively destroyed during acid hydrolysis in routine amino acid analysis and its determination requires a separate analytical procedure. The variability in contents and apparent ileal digestibility for 6-week-old broiler chickens of tryptophan in 74 samples representing 24 feedstuffs are presented in this paper. The average ileal tryptophan digestibility coefficient in wheat was 0.83, in sorghum and triticale 0.75, maize 0.71, soybean meal 0.84, sunflower meal 0.81, canola meal 0.78 and cottonseed meal 0.75. Among the grain legumes, tryptophan in lupins was better digested than that in chickpeas, fababeans and field peas. Among the animal protein meals, the tryptophan digestibility coefficients in fish meal (0.77) and blood meal (0.84) were substantially higher than those in meat meal (0.64), meat-and-bone meal (0.63) and feather meal (0.52). Marked variations in tryptophan digestibility were also observed among samples of fish meal, meat-and-bone meal and meat meal, highlighting significant batch-to-batch differences. For most feedstuffs, considerable variability was observed in the tryptophan concentrations, but such variations were not reflected in digestibility coefficients. (c) 2006 Society of Chemical Industry.

COMPARAÇÃO DE MODELOS DE AVALIAÇÃO DE DESEMPENHO DE EQUIPES MULTIFUNCIONAIS BASEADOS EM CONCEITOS DE INTERAÇÃO DE GRUPOS E FERRAMENTAS DE ANÁLISE COMPORTAMENTAL

Avaliação de desempenho de equipes multifuncionais é um conceito que tem sido abordado mais freqüentemente nas últimas duas décadas. Diversas teorias e conceitos foram desenvolvidos para tornar as avaliações menos qualitativas ou fundamentadas em percepções, compreendendo um conjunto de diferentes técnicas interpretativas que visam descrever e decodificar os componentes de um sistema complexo de significados. Com esse foco o projeto comparou três modelos de avaliação de desempenho de equipes. O primeiro modelo baseado na personalidade do participante, afirma que os resultados das equipes são influenciados pela seleção prévia dos participantes e que as características individuais desses participantes são críticas para o desempenho da equipe. O segundo modelo fundamenta suas afirmações nas relações interconectadas de positividade e negatividade; questionamento e argumentação e atuação em equipe. O terceiro modelo baseado no processo de interação de grupos também avalia as relações que influenciam o alto desempenho de equipes multifuncionais. Os três modelos foram comparados, através de um estudo de caso único em indústria química paulista, medindo-se os resultados de correlação das equipes e as interações entre os participantes das equipes. As metas atingidas pelas equipes foram utilizadas para suportar os resultados das avaliações dos modelos como sistema de avaliação de equipes. Pode-se concluir que houve uma aproximação satisfatória confirmando a influência sugerida pelos modelos avaliados. A comparação entre os três modelos não permitiu afirmar qual dos três modelos é mais eficaz para avaliação de equipes. Entretanto, é possível, sugerir que a combinação de elementos dos três modelos permitirá a construção de um processo eficaz e prático de avaliação de equipes.(AU)

Identification of optically clear regions of ternary polymer blends using a novel rapid screening method

The application of a rapid screening method for the construction of ternary phase diagrams is described for the first time, providing detailed visualization of phase boundaries in solvent-mediated blends. Our new approach rapidly identifies ternary blend compositions that afford optically clear materials, useful for applications where transparent films are necessary. The use of 96-well plates and a scanning plate reader has enabled rapid optical characterization to be carried out by transmission spectrophotometry (450 nm), whilst the nature and extent of crystallinity was examined subsequently by wide angle X-ray scattering (WAXS). The moderating effect of cellulose acetate butyrate can be visualized as driving the position of the phase boundaries in poly(l-lactic acid)/polycaprolactone (PLLA/PCL) blends. More surprisingly, the boundaries are critically dependent on the molecular weight of the crystallizable PLLA and PCL, with higher molecular weight polymers leading to blends with reduced phase separation. On the other hand, the propensity to crystallize was more evident in shorter chains. WAXS provides a convenient way of characterizing the contribution of the individual blend components to the crystalline regions across the range of blend compositions. © 2013 Society of Chemical Industry.

Identifying the active phase in Cs-promoted MgO nanocatalysts for triglyceride transesterification

Background: Biodiesel is a clean-burning, renewable and biodegradable diesel fuel substitute derived from animal fats and plant oils, which may play an important role in replacing diminishing fossil fuel reserves and combating climate change. Conventional biodiesel production uses soluble base catalysts, such as Na or K alkoxides, to convert oils into fuel, and as a result requires energy intensive aqueous quench cycles to isolate the biodiesel product. Results: Cs-doping nanoparticulate MgO, prepared via a novel, supercritical sol-gel method, yields a solid base catalyst with improved activity for the transesterification of pure triacylglycerides (TAGs) and olive oil. Conclusion: Here, X-ray absorption spectroscopy (XAS) is used to probe the local chemical environment of Cs atoms in order to identify the nature of the catalytically active species as CsMg(CO)(HO). © 2013 Society of Chemical Industry.

Enhanced selective aerobic alcohol oxidation through nanoengineered catalyst supports

The selective conversion of alcohols to their carbonyl derivatives is a critical step towards a sustainable chemical industry. Heterogeneous Pd catalysts represent some of the most active systems known, even so further studies into the active species and role of support are required. Through controlling support mesostructure, using non-interconnected SBA-15 and interlinked SBA-16 and KIT-6, we have evaluated the role of pore architecture on supported Pd nanoparticles and their subsequent activity for liquid phase aerobic allylic alcohol selective oxidation.[1,2] These synthesised silica supports exhibit high surface areas (>800 m2g-1), and similar mesopore diameters (3.5 to 5 nm), but differ in their pore connectivity and arrangement; p6mm (SBA-15), I3mm (SBA-16) and I3ad (KIT-6). When evaluated alongside commercial non-mesoporous silica (200 m2 g-1) they promote enhanced Pd dispersion with interpenetrating assemblies providing further elevation. Macropore introduction into SBA-15, producing a hierarchical macro-mesoporous silica (MM-SBA-15), allows control over mesopore length and accessibility which escalates Pd distribution to levels akin to KIT-6 and SBA-16. Controlling dispersion, and likewise nanoparticle size, is thus facilitated through the choice of support and additionally Pd loading, with cluster sizes spanning 3.2 to 0.8 nm. X-ray spectroscopies indicate nanoparticles are PdO terminated with the oxide content a function of dispersion. Kinetic studies allude to surface PdO being the active site responsible, with a constant TOF observed, independent of loading and support. This confirms activity is governed by PdO density, whilst also overruling internal mass diffusion constraints. MM-SBA-15 facilitates superior activity and TOFs for long chain acyclic terpene alcohols due to reduced internal mass transport constraints.

Recent advances in the heterogeneously catalysed aerobic selective oxidation of alcohols

The heterogeneously catalysed selective aerobic oxidation of alcohols is an important tool for the synthesis of valuable chemical intermediates and a hot topic within both academic and industrial arenas. In this mini-review, selected aspects of catalyst formulation, process operating conditions, and progress in identifying the active sites and surface reaction mechanisms notably through the application of synchrotron radiation, are highlighted. © 2010 Society of Chemical Industry.

Academic Experience and Personal Abilities in Analytical Chemistry Education

Report published in the Proceedings of the National Conference on "Education and Research in the Information Society", Plovdiv, May, 2016

Dissociative adsorption of methane on the Cu and Zn doped (111) surface of CeO2

The development of economical heterogeneous catalysts for the activation of methane is a major challenge for the chemical industry. Screening potential candidates becomes more feasible using rational catalyst design to understand the activity of potential catalysts for CH4 activation. The focus of the present paper is the use of density functional theory to examine and elucidate the properties of doped CeO2. We dope with Cu and Zn transition metals having variable oxidation state (Cu), and a single oxidation state (Zn), and study the activation of methane. Zn is a divalent dopant and Cu can have a +1 or +2 oxidation state. Both Cu and Zn dopants have an oxidation state of +2 after incorporation into the CeO2 (111) surface; however a Hubbard +U correction (+U = 7) on the Cu 3d states is required to maintain this oxidation state when the surface interacts with adsorbed species. Dissociation of methane is found to occur locally at the dopant cations, and is thermodynamically and kinetically more favorable on Zn-doped CeO2 than Cu-doped CeO2. The origins of this lie with the Zn(II) dopant moving towards a square pyramidal geometry in the sub surface layer which facilitates the formation of two-coordinated surface oxygen atoms, that are more beneficial for methane activation on a reducible oxide surface. These findings can aid in rational experimental catalyst design for further exploration in methane activation processes.

Highlights from Faraday Discussion: Designing New Heterogeneous Catalysts, London, UK, April 2016

The Faraday Discussion on the design of new heterogeneous catalysts took place from 4-6 April 2016 in London, United Kingdom. It brought together world leading scientists actively involved in the synthesis, characterisation, modelling and testing of solid catalysts, attracting more than one hundred delegates from a broad spectrum of backgrounds and experience levels-academic and industrial researchers, experimentalists and theoreticians, and students. The meeting was a reflection of how big of an impact the ability to control and design catalysts with specific properties for particular processes can potentially have on the chemical industry, environment, economy and society as a whole. In the following, we give an overview of the topics covered during this meeting and briefly highlight the content of each presentation.

Experimental viscosity measurements of biodiesels at high pressure

The viscosity of biodiesels of soybean and rapeseed biodiesels blended with mineral diesel fuel were measured at pressures of up to 200 MPa. Using a falling sinker-type viscometer reproducible viscosity data were obtained based on the time taken for a sinker to descend a fixed distance down an enclosed tube under the influence of gravity. Measurements were taken using pressures which correspond to those of interest in automotive common rail diesel engines, and at temperatures of between 25oC and 80oC. In all cases, the viscosity of the biodiesel blends were found to increase exponentially for which the blends were noted as being more viscous than pure mineral fuels. A pressure-freezing effect was not observed for the blends.

Understanding immobilised enzymes by NMR spectroscopy

Enzyme immobilisation is the conversion of a soluble enzyme molecule into a solid particle form. This allows the recovery of the enzyme catalyst for its re-use and avoids protein contamination of the product streams. A better understanding of immobilised enzymes is necessary for their rational development. A more rational design can help enormously in the applicability of these systems in different areas, from biosensors to chemical industry. Immobilised enzymes are challenging systems to study and very little information is given by conventional biochemical analysis such as catalytic activity and amount of protein. Here, solid-state NMR has been applied as the main technique to study these systems and evaluate them more precisely. Various approaches are presented for a better understanding of immobilised enzymes, which is the aim of this thesis. Firstly, the requirements of a model system of study will be discussed. The selected systems will be comprehensibly characterised by a variety of techniques but mainly by solid-state NMR. The chosen system will essentially be the enzyme α-chymotrypsin covalently immobilised on two functionalised inorganic supports – epoxide silica and epoxide alumina – and an organic support – Eupergit®. The study of interactions of immobilised enzymes with other species is vital for understanding the macromolecular function and for predicting and engineering protein behaviour. The study of water, ions and inhibitors interacting with various immobilised enzyme systems is covered here. The interactions of water and sodium ions were studied by 17O and 23Na multiple-quantum techniques, respectively. Various pore sizes of the supports were studied for the immobilised enzyme in the presence of labelled water and sodium cations. Finally, interactions between two fluorinated inhibitors and the active site of the enzyme will be explored using 19F NMR, offering a unique approach to evaluate catalytic behaviour. These interactions will be explored by solution-state NMR firstly, then by solid-state NMR. NMR has the potential to give information about the state of the protein in the solid support, but the precise molecular interpretation is a difficult task.

Modulaarisen jatkuvatoimisen kiteyttimen markkinapotentiaali ja toiminnan todentaminen

Valmistettaessa kiteisiä tuotteita kemianteollisuudessa jatkuvatoimisuudella voidaan saavuttaa merkittäviä etuja panosprosesseihin verrattuna. Toistettavuus ja tuotekiteiden ominaisuudet paranevat ja kustannussäästöjä saadaan sekä kiteytyksestä että mahdollisesta jatkokäsittelyn yksinkertaistumisesta. Hienokemianteollisuudessa panoskiteytys on kuitenkin edelleen vallitseva kiteytysmenetelmä pienten tuotantovolyymien, tuotteiden vaihtelevuuden ja panoskiteyttimien puhdistamisen helppouden vuoksi. Ultraäänen vaikutusta kiteytykseen on tutkittu kattavasti viimevuosina. Tehoultraäänen aiheuttamalla kavitaatiolla on havaittu olevan merkittäviä kiteytystä edistäviä vaikutuksia. Yhdistämällä jatkuvatoimiseen putkivirtauskiteyttimeen tehoultraäänen tukkeutumista estävä ja kiteytystä edistävä vaikutus saadaan systeemi, jota voidaan pitää varteenotettavana vaihtoehtona panoskiteyttimille hienokemianteollisuudessa. Tässä työssä määritettiin markkinapotentiaali jatkuvatoimiselle ultraääniprosessointijärjestelmälle eurooppalaisten hienokemianteollisuuden yritysten parissa. Markkinapotentiaalin määritys tehtiin makrotasolla nojautumalla toimialatilastoihin, jotka poimittiin Amadeus-tietokannasta. Jatkuvatoimista ultraääniprosessointijärjestelmää myös kehitettiin edelleen lisäämällä moduulien määrää kolmesta viiteen, testaamalla eri putkivaihtoehtoja ja määrittämällä korkeimmat käyttökonsentraatiot putkivirtauskiteyttimelle kolmella eri malliaineella. Ultraäänen vaikutusta viipymäaikajakaumaan tarkasteltiin pulssikokeiden avulla kolmen eri putkivaihtoehdon tapauksessa. Ultaääniprosessointijärjestelmän putkivaihtoehdoista 6 mm sisähalkaisijaisessa teräsputkessa saavutettiin korkeammat saannot ja pienemmät tuotekiteet kuin 4 mm sisähalkaisijaisessa teräsputkessa. Ultraääni ei läpäissyt 4 mm sisähalkaisijaista polyamidiputkea riittävän tehokkaasti ehkäistäkseen systeemin tukkeutumista.