Dye-labelled polymer chains at specific sites: Synthesis by living/controlled polymerization

Dye-labelled polymer chains are extremely useful in many fields, such as optical imaging, signal amplification in biological diagnostics, light-harvesting and photochromic materials as well as in fluorescence studies about intra- and inter-molecular polymer chain associations, conformations and dynamics of polymer chains. However, in many cases, it is particularly useful that the dye is localized at a specific site, such as the chain-end or the junction between blocks. With the development of living/controlled polymerization techniques, end- and junction-functionalized polymers can be prepared with controlled molecular weights from a huge variety of monomers. This review highlights the state of the art in the strategies leading to one and only one precisely localized dye per polymer chain. Such dye can be introduced at three different steps of the polymerization: i) at the very beginning via the initiator or a chain transfer agent, ii) during polymerization via a functional monomer or a quencher, or iii) after polymerization via covalent binding of a dye-derivative.     

Use of coffee by‐products for the cultivation of Pleurotus citrinopileatus and Pleurotus salmoneo‐stramineus and its impact on biological properties of extracts thereof

Incorporating spent coffee grounds (SCGs), a by‐product from coffee brewing, in growth substrate of beneficial edible mushrooms is an approach that has to be further studied due to its potential positive outcomes: environmental impact mitigation, production costs reduction and beneficial impact on consumer health. Hence, cultivation of Pleurotus citrinopileatus and Pleurotus salmoneo‐stramineus was tested using SCG which enabled maximum production yield of P. citrinopileatus which was of 25.1% (w/w). Variable antidiabetic potential was observed between aqueous and enzymatic extracts (3.8%–29% inhibition) regardless species and substrates, whereas aqueous extract of P. citrinopileatus grown in substrate without SCG stood out presenting the highest antioxidant activity and inhibition activity of angiotensin I‐converting enzyme (IC₅₀ = 123 μg mL^?1). Ethanolic and aqueous extracts of both Pleurotus species grown in the presence or absence of SGC proved to be an interesting prebiotic source for growth of Bifidobacterium animalis Bo in comparison with fructooligosaccharides (FOS).     

Heterocyclic polyimides containing siloxane groups in the main chain

BACKGROUND: Among the polymers widely studied for applications in advanced techniques, aromatic polyimides have received considerable attention due to their outstanding thermal stability associated with good electrical and mechanical properties. However, these polymers are usually difficult to process, being insoluble and without a glass transition. To improve the processing characteristics of polyimides, modification of their structure is often achieved by the introduction of flexible linkages in the macromolecular chain or various substituents on the aromatic rings. RESULTS: A series of polyimides and intermediate polyamidic acids were synthesized from aromatic oxadiazole‐diamines and a dianhydride containing a siloxane bridge (? R₂Si? O? SiR₂? ). These polymers exhibit good solubility in certain organic solvents and can be cast into thin and very thin films from their solutions. They exhibit high thermal stability with decomposition being above 440 °C and relatively low glass transition temperatures in the range 160–190 °C. These polymers show strong photoluminescence in the blue spectral region. CONCLUSION: The introduction of oxadiazole rings together with siloxane groups into the chains of aromatic polyimides gives highly thermostable polymers with remarkable solubility and film‐forming ability and that emit blue light, being attractive for applications in micro‐ and nanoelectronics and other related advanced fields. Copyright © 2009 Society of Chemical Industry     

Three-layer flow membrane system on a microchip for investigation of molecular transport

A stable three-layer flow system, water/organic solvent/water, has been successfully applied for the first time in a microchannel to get rapid transport through an organic liquid membrane. In the continuous laminar flow region, the analyte (methyl red) was rapidly extracted across the microchannel from the donor to the acceptor phase through the organic solvent phase (cyclohexane). Thermal lens microscopy was used to monitor the process. The thickness of the organic phase, sandwiched by the two aqueous phases, was approximately 64 microm, and it was considered as a thin liquid organic membrane. Permeability studies showed the effects of molecular diffusion, layer thickness, and organic solvent-water partition coefficient on the molecular transport. In the microchip, complete equilibration was achieved in several seconds, in contrast to a conventionally used apparatus, where it takes tens of minutes. The thickness of the organic and aqueous boundary layers was defined as equal to the microchannel dimensions, and the organic solvent-water partition coefficient was determined on a microchip using the liquid/liquid extraction system. Experimental data on molecular transport across the organic membrane were in agreement with the calculated permeability based on the three-compartment water/organic solvent/water model. This kind of experiment can be performed only in a microspace, and the system can be considered as a potential biological membrane for future in vitro study of drug transport.     

Growth in height of indigenous and non indigenous Chilean children

The aim of this study was to compare growth curves of stature in indigenous and non-indigenous children belonging to two levels of poverty and to establish the onset and evolution of the deficit. Children of indigenous and non-indigenous background living in communities of extreme and low poverty in Chile were studied and their height-for-age Z-score from birth until 6 year of age were compared. Mean weight at birth was within normal range, and no differences were found in ethnicity and levels of poverty. Length at birth was below the reference with the exception of the non indigenous newborn from counties of low poverty. Deficit in growth showed an early start, furthermore in indigenous children belonging to the extreme poverty, is from birth and progress through the 18 months. At 72 months the deficit reached -1.1 z scores in the indigenous of the extreme poverty versus -0.7 in the non indigenous group. Children from the low poverty had a Z-score of -0.4 z scores at 72 months without differences between ethnias. Indigenous of the extreme poverty had less accumulative growth while the indigenous of the low poverty areas growth satisfactory without differences with the non indigenous.     

From market fixing to market-creating: a new framework for innovation policy

Many countries are pursuing innovation-led “smart” growth, which requires long-run strategic investments and public policies that aim to create and shape markets, rather than just “fixing” markets or systems. Market creation has characterized the kind of mission-oriented investments that led to putting a man on the moon and are currently galvanizing green innovation. Mission-oriented innovation has required public agencies to not only “de-risk” the private sector, but also to lead the direct creation of new technological opportunities and market landscapes. This paper considers four key issues that arise from a market-creating framework for policy: (1) decision-making on the direction of change; (2) the nature of (public and private) organizations that can welcome the underlying uncertainty and discovery process; (3) the evaluation of mission-oriented and market-creation policies; and (4) the ways in which both risks and rewards can be shared so that smart growth can also result in inclusive growth.     

Microbial and enzymatic stability of fruit juice-milk beverages treated by high intensity pulsed electric fields or heat during refrigerated storage

The influence of high intensity pulsed electric fields (HIPEF) treatment (35 kV/cm, bipolar 4 μs square wave pulses at 200 Hz) on the inactivation of Listeria innocua in fruit juice–whole (FJ–WM) or skim milk (FJ–SM) beverages was assessed. As well, the effects of HIPEF or conventional thermal (90 °C 60 s) processing in terms of microbial and enzymatic stability and changes on physicochemical parameters of the beverages during refrigerated storage were also studied. HIPEF and thermal processing ensured the microbial stability of the beverages during 56 days at 4 °C without significant changes on pH, acidity and soluble solid content values. Thermal processing was more effective than HIPEF in reducing Pectin Methyl Esterase (PME) activity in FJ–SM and FJ–WM beverages since its activity was reduced by 70.66% and 87.33%, respectively. With regards to Polygalacturonase (PG), HIPEF treatment reduced by 26.92% and 20.93% the enzyme activity in the FJ–WM and FJ–SM beverages, respectively, whereas thermal treatment did not inactivate PG in both beverages. HIPEF or thermally-treated samples showed higher viscosity than the untreated ones, being this increment more pronounced in the beverages with whole milk. Therefore, HIPEF processing may be a feasible technology in order to obtain shelf stable and fresh-like fruit juice-milk beverages.     

NbO/Nb2O5 core–shells by thermal oxidation

Niobium oxides have been reported as an alternative to tantalum, and its oxide, for the production of capacitors, but these materials still require a further and exhaustive study. Understanding the dynamics of the oxidation process from NbO to Nb₂O₅ is essential to explain and control the properties of a niobium oxide based capacitors. In situ XRD analysis of NbO powders was performed from 100 to 1100 °C, which showed a temperature range where only amorphous phase is present. The capacitor anodes, formed from the same type of NbO powders, were then heat-treated in air from room-temperature (RT) to 550 °C and recorded with a video camera to see the colour shift. The presence of core–shell structures and the increase of the shell thickness/amount with temperature are visible in SEM. Finally, in situ spectroscopy studies were performed, in order to observe the interference spectra which are responsible for the observed colours.     

Combustion synthesis of copper catalysts for selective CO oxidation

Copper catalysts supported on ceria, zirconia and niobia were prepared by combustion method with urea, containing a CuO loading of 6 wt.%, and tested on selective oxidation of CO. The characterization of the samples by X-ray diffraction (XRD) presented the formation of solid solution on CuO–CeO₂ catalyst and a change in crystalline structure of the support with copper insertion on ZrO₂ and Nb₂O₅ catalysts. The analysis of temperature-programmed reduction (TPR) revealed different interaction degrees of copper with the supports, with reduction peaks between 222 and 390 °C. The temperature-programmed desorption of CO (TPD-CO) profiles showed formation of CO₂ and H₂ only for the ceria and zirconia catalysts. In relation to the catalytic tests, the CuO–CeO₂ catalyst presented the best performance, with CO conversion of 95% at 150 °C up to 45 h on stream, and CO₂ selectivity of 55%.     

Moisture sorption isotherms and thermodynamic properties of apple Fuji and garlic

The moisture equilibrium isotherms of garlic and apple were determined at 50, 60 and 70 °C using the gravimetric static method. The experimental data were analysed using GAB, BET, Henderson–Thompson and Oswin equations. The isosteric heat and the differential entropy of desorption were determined by applying Clausius–Clapeyron and Gibbs–Helmholtz equations, respectively. The GAB equation showed the best fitting to the experimental data (R² > 99% and E% < 10%). The monolayer moisture content values for apple were higher than those for garlic at the studied temperatures; the values varied from 0.050 to 0.056 and from 0.107 to 0.168 for garlic and apple, respectively. The isosteric heat and the differential entropy of desorption were estimated in function of the moisture content. The values of these thermodynamic properties were higher for apple (in range 48–100 kJ mol^?1 and 14–150 J mol^?1 K^?1) than for garlic (in range 43–68 kJ mol^?1 and 0–66 J mol^?1 K^?1). The water surface area values decreased with increasing temperature. The Kelvin and the Halsey equations were used to calculate the pore size distribution.