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Renewable Sources (renewable + source)
Selected AbstractsHydroxypropyl-,-Cyclodextrin-Capped Palladium Nanoparticles: Active Scaffolds for Efficient Carbon-Carbon Bond Forming Cross-Couplings in WaterADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Jaqueline Abstract A new approach for the preparation of palladium nanoparticles in water from a renewable source, 2-hydroxypropyl-,-cyclodextrin (,-HPCD), which acts both as a reductant and capping agent, is presented. The palladium nanoparticles were characterized by using dynamic light scattering (DLS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), which revealed the formation of spherical particles in the size range of 2,7,nm. Further analysis by Fourier-transform infrared spectroscopy (FT-IR) and 1H,NMR did not show covalent bonds between cyclodextrins and palladium nanoparticles, suggesting that ,-HPCD is only physically adsorbed on the nanoparticle surface, presumably through hydrophobic interactions which limit the mutual coalescence of nanoclusters. The catalytic activity was tested in Suzuki, Heck and Sonogashira reactions in neat water, providing good yields and selectivities of coupling products under very low Pd loadings (0.5,0.01,mol%). Remarkably, the nanocatalyst showed significant stability hence the aqueous phase remained active for four subsequent runs. The combination of a binding site for substrates (the HPCD cavity) and a reactive centre (Pd core) provides a potential to explore functional catalysis in aqueous medium. [source] Optimization of enzymatic extraction of ferulic acid from wheat bran, using response surface methodology, and characterization of the resulting fractionsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2009Hélène Barberousse Abstract BACKGROUND: The agro-industries generate thousands of tons of by-products, such as bran or pulps, each year. They are, at best, used for cattle feeding. Through biocracking, this biomass may constitute a renewable source for various molecules of interest for the industry. For instance, ferulic acid, a compound showing antioxidant ability, is found in abundance in cereal bran. Its release depends mainly on the breaking of its ester linkage to other constitutive elements of the cell wall, such as arabinoxylans. Response surface methodology was used to evaluate the effects of ferulic acid esterase (FAE) and xylanase activities, as well as incubation time and temperature, on ferulic acid extraction yield from wheat bran. Under optimized conditions, the composition of the hydrolysate and of residual bran were compared to native bran. RESULTS: Experiments carried out under the predicted optimal conditions (FAE amount, 27 U g,1; xylanase amount, 304 U g,1; incubation time, 2 h; and temperature, 65 °C) led to an extraction yield of 52.8%, agreeing with the expected value (51.0%). The crude ferulic acid fraction was purified with Amberlite XAD16, leading to a final concentration of 125 µg mL,1 of ferulic acid in ethanol. The antioxidant capacity of this purified fraction was evaluated by the DPPH· scavenging method: it exhibited better efficiency (EC50 = 10.6 µmol L,1 in ferulic acid) than the ferulic acid standard (EC50 = 13.7 µmol L,1). CONCLUSION: These results confirm the potential of wheat bran valorization in the field of natural antioxidant extraction, possibly viable in an industrial scheme. Copyright © 2009 Society of Chemical Industry [source] Megakaryocytes derived from human embryonic stem cells: a genetically tractable system to study megakaryocytopoiesis and integrin functionJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2 2006M. GAUR Summary.,Background:,The platelet fibrinogen receptor, a heterodimer consisting of integrin subunits ,IIb and ,3, is required for platelet aggregation, spreading, and hemostasis. Platelet agonists such as thrombin and adenosine diphosphate (ADP) lead to the activation of ,IIb,3, thereby enhancing its affinity and avidity for binding fibrinogen (inside-out signaling). Furthermore, fibrinogen binding to ,IIb,3 triggers cytoskeletal changes and granule release (outside-in signaling).Aim:,Genetic approaches to characterize the molecular pathways involved in ,IIb,3 signaling are not possible with anucleate blood platelets. Therefore, we have established an OP9 stromal cell co-culture system to generate megakaryocytes from human embryonic stem cells (hESCs).Results:,,IIb,3 activation, measured by soluble fibrinogen binding to hESC-derived megakaryocytes, /GPIb,+ cells, is readily detectable following stimulation with known platelet agonists. Dose,response curves for peptide agonists specific for the two platelet thrombin receptors, protease-activated receptor 1 (PAR1) and PAR4, show a relative responsiveness that mirrors that of human platelets, and sub-maximal ADP responses are augmented by epinephrine. Moreover, hESC-derived megakaryocytes undergo lamellipodia formation, actin filament assembly, and vinculin localization at focal adhesions when plated on a fibrinogen-coated surface, characteristic of ,IIb,3 outside-in signaling. Undifferentiated hESCs genetically modified by lentiviral infection can be cloned and maintained in an undifferentiated state and then differentiated into megakaryocytes capable of ,IIb,3 activation.Conclusion:,Using hESCs, we have developed a renewable source of human megakaryocytes, and a genetically tractable system for studying megakaryocytopoiesis and ,IIb,3 signaling in the native cellular environment. [source] Influence of oil type on the performance characteristics of a two-axial groove journal bearingLUBRICATION SCIENCE, Issue 9 2009D. M. C. McCarthy Abstract The use of environmentally adapted lubricants (EALs) is a subject of growing interest to industry as legislation increasingly demands the replacement of mineral oil lubricants. Vegetable-based fluids are widely seen as providing lubricants from a renewable source, as well as meeting demands for improved biodegradability. However, at present, utilization of such fluids is limited due to their rapid oxidation. EALs produced from other base stocks (i.e. synthetic esters) have been shown to provide performance benefits in hydrodynamic thrust bearings. In the present study, a hydrodynamic journal bearing test rig has been employed to compare the performance of three EALs (a VG32 saturated ester, rapeseed base fluid and a propylene glycol dioleate) relative to three mineral turbine oils (ISOVG32, ISOVG46 and ISOVG68) in the hydrodynamic regime. Results are given in terms of temperature, power loss and minimum film thickness. The impact of oil viscosity index is also discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Synthesis of biodegradable polyhydroxyalcanoate copolymer from a renewable source by alternate feedingPOLYMER ENGINEERING & SCIENCE, Issue 10 2008Silvia M.F. Pereira Polyhydroxyalcanoates copolymers with 3-hydroxybutirate (3HB) and 3-hydroxyvalerate (3HV) co-monomers, P3(HB-co-x%HV), were produced in fed-batch culture by Ralstonia eutropha DSM428 using fructose as a single carbon source in the first step and adding propionic acid in the second step by alternating feeding. Polymer yield was 0.18 g/L with a content of 24 mol% of the 3HV fraction determined by 1H NMR. NMR measurements indicated that the polymer obtained is isotactic. The copolymer attained 35% of crystallinity according to X-ray diffraction measurements, and two (020) planes were observed. Thermal behavior presented melting temperature at 154°C and the crystallization temperature was 65°C. A glass transition temperature was observed at ,10°C. Average molecular weight measured by GPC was 4.9 × 105 Dalton. Isothermal radial growth rates of spherulites of P3(HB-co-24%HV) were studied. All experimental facts and the analysis of the sequence distribution of diads and triads of 3HB and 3HV units led to the conclusion that it is not a completely statistical random copolymer once it contains different types of segments. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers. [source] The Contribution of Bioenergy to a New Energy ParadigmEUROCHOICES, Issue 3 2005Daniel De La Torre Ugarte Biomass is a widely available resource that is receiving increased consideration as a renewable substitute for fossil fuels. Developed sustainably and used efficiently, it can induce growth in developing countries, reduce oil demand, and address environmental problems. The potential benefits include: reduction of greenhouse gases, recuperation of soil productivity and degraded land, economic benefits from adding value to agricultural activities and improving access to and quality of energy services. The production of bioenergy involves a range of technologies, including solid combustion, gasification, and fermentation. These technologies produce energy from a diverse set of biological resources - traditional crops, crop residues, energy-dedicated crops, dung, and the organic component of urban waste. The results are bioenergy products that provide multiple energy services: cooking fuel, heat, electricity and transportation fuels. It is this very diversity that holds the potential of a win-win-win for the environment, social and economic development. Bioenergy has to be viewed not as a replacement for oil, but as an element of a portfolio of renewable sources of energy. Coherent and mutually supportive environmental and economic policies may be needed to encourage the emergence of a globally dispersed bioenergy industry that will pursue a path of sustainable development. La biomasse est une resource largement répandue, qui commence à retenir l'attention comme substitut renouvelable aux énergies fossiles. En l'utilisant de façon efficace et durable, on peut accélérer la croissance des pays en voie de développement, réduire la demandepour le pétrole et résoudre certains problèmes d'environnement. Au nombre des bénéfices potentiels il faut mettre : la réduction des émissions de gaz à effet de serre, la reconstitution de la fertilité dessols et des terres dégradées, les avantages économiques liés à l'accroissement de la production agricole et à l'amélioration des services énergétiques, tant en qualité qu'en accessibilité. La production de bioénergie met en oeuvre un large éventail de techniques parmi lesquelles la combustionde produits solides, la gazéification et la fermentation. Elles produisent de l'énergie à partir d'une grande variété de sources biologiques : cultures traditionnelles, résidus de cultures, cultures spécialisées, fumiers et déchets organiques urbains. Les produits bio-énergétiques qui en résultent couvrent une grande variété d'usages : énergie de cuisson, chauffage, électricité et transports. C'est précisément sur cette diversité que repose l'espoir de gains dans toutes les directions, sociales, environnementales et économiques. Il ne faut pas voir la bioénergie comme un simple substitut au pétrole, mais comme un portefeuille de ressources renouvelables. Pour encourager l'émergence d'une industrie bioénergétique largement répandue et susceptible de contribuer au développement durable, il faudra sans doute élaborer des politiques économiques et environnementales cohérentes, capables de se soutenir mutuellement. Bei Biomasse handelt es sich umeine weithin verfügbare Ressource, welche zunehmend als erneuerbarer Ersatz für fossile Brennstoffe in Betracht gezogen wird. Sie kann bei nachhaltiger Entwicklung und effizienter Nutzung zu Wachstum in den Entwicklungsländern führen, die Nachfrage nach Öl senken und dazu beitragen, die Umweltprobleme in den Griff zu bekommen. Zu den potenziellen Nutzen gehÖren: Verringerung der Treibhausgase, Wiederherstellung von Bodenproduktivität sowie von erodiertem Land, wirtschaftlicher Nutzen durch zusätzliche Wertschöpfung aus landwirtschaftlicher Aktivität und besserer Zugang zu und Qualität in der Energieversorgung. Bei der Erzeugungvon Bioenergie kommen eine Reihe von verschiedenen Technologien zur Anwendung, z.B. Verbrennung fester Brennstoffe, Vergasung sowie Gärung. Diese Technologien erzeugen Energie mittels unterschiedlicher biologischer Ressourcen , traditionelle Feldfrüchte und deren Rückstände, spezielle Energiepflanzen, Mist sowie der organische Anteil städtischer Abfälle. Die daraus erzeugte Bioenergie kann zum Kochen, zum Heizen, als Elektrizität oder als Treibstoff genutzt werden. Gerade in dieser Vielfalt liegt der potenzielle Gewinn für die Umwelt und die soziale sowie die wirtschaftliche Entwicklung. Bioenergie sollte nicht als ein Ersatz für Öl, sondern als Bestandteil des Portfolios erneuerbarer Energiequellen angesehen werden. Kohärente und sich gegenseitig unterstützende ökologische und Ökonomische Politikmaßnahmen könntenerforderlich sein, um die Entstehung einer global verbreiteten Bioenergieindustrie zu begünstigen, welche eine nachhaltige Entwicklung verfolgt. [source] Solar-Energy Production and Energy-Efficient Lighting: Photovoltaic Devices and White-Light-Emitting Diodes Using Poly(2,7-fluorene), Poly(2,7-carbazole), and Poly(2,7-dibenzosilole) DerivativesADVANCED MATERIALS, Issue 8 2010Serge Beaupré Abstract World energy needs grow each year. To address global warming and climate changes the search for renewable energy sources with limited greenhouse gas emissions and the development of energy-efficient lighting devices are underway. This Review reports recent progress made in the synthesis and characterization of conjugated polymers based on bridged phenylenes, namely, poly(2,7-fluorene)s, poly(2,7-carbazole)s, and poly(2,7-dibenzosilole)s, for applications in solar cells and white-light-emitting diodes. The main strategies and remaining challenges in the development of reliable and low-cost renewable sources of energy and energy-saving lighting devices are discussed. [source] Natural gas internal combustion engine hybrid passenger vehicleINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2008S. Wright Abstract The implementation of hybrid electric vehicles powered with alternative fuels is critical in reducing national dependence on imported crude oil, addressing the detrimental environmental impact of increasing petroleum usage worldwide, and sustaining the national economy. The question is not whether changes should be made, but instead centers on identifying pathways that will lead to the greatest environmental and economic benefits. To avoid misuse of limited infrastructure investment, the objective of this research is to consider a broad range of relevant factors to determine desirable power plant,fuel combinations for hybrid electric vehicles. In the long term, fuel cells may dominate this application, but at least in the short term, proton exchange membrane fuel cells (PEMFCs) will not likely offer immediate substantial benefit over internal combustion (IC) engines. Environmentally friendly operation of the PEMFC results partly due to low-temperature operation but primarily due to the requirement of a clean fuel, hydrogen. In addition, the differential benefits from power plant choice can be overshadowed by the advantages obtained from hybrid electric vehicle technology and alternative fuels. Consequently, the fuel flexibility of IC engines provides an advantage over the relatively fuel inflexible PEMFC. The methane/hythane IC engine hybrid option, as developed and presented here, is a promising pathway that avoids the barriers encountered with conventional non-hybrid natural gas vehicles, namely range, power and fueling infrastructure difficulties. Dynamometer testing of the natural gas hybrid prototype on the certification FTP-72 duty cycle revealed very low emissions and mileage greater than 33 miles per gallon gasoline equivalent. This hybrid option utilizes a domestic, cost-effective fuel with renewable sources. With multi-fuel capability (methane, hythane and gasoline) it is also designed for use within the emerging hydrogen market. This hybrid option offers reliability and cost-effective technology with immediate wide spread market availability. Copyright © 2007 John Wiley & Sons, Ltd. [source] Minimal effects of wind turbines on the distribution of wintering farmland birdsJOURNAL OF APPLIED ECOLOGY, Issue 6 2008Claire L. Devereux Summary 1Energy production from wind power is increasing rapidly in Europe to help combat the threats from global warming. For example, the European Commission have set a target for 20% of EU energy to come from renewable sources by 2020. In recent decades, biodiversity on European farmland has fallen dramatically due to agricultural intensification. Agri-environment schemes (AES) have been implemented across the EU, in part at least, to combat these declines. Significant numbers of turbines are, and will be, built on farmland. There is, therefore, a potential conflict between wind turbines and AES on farmland. 2Various mechanisms potentially cause wind turbines to alter bird distribution including noise and physical structure. 3We show that turbine location (controlling for other effects such as boundary location and crop type) did not affect the distribution of four functional groups of wintering farmland birds (seed-eaters, corvids, gamebirds and Eurasian skylarks) at differing distances from wind turbines ranging from 0,150 m to 600,750 m. The only species for which distribution was related to the presence of wind turbines was the largest and least manoeuvrable (common pheasant Phasianus colchicus L.). 4In a further analysis of data collected at 0,75 m and 75,150 m from turbines, we found no evidence to suggest that farmland birds in our study avoided areas close to wind turbines. 5Synthesis and applications. This is the first evidence suggesting that the present and future location of large numbers of wind turbines on European farmland is unlikely to have detrimental effects on farmland birds (at least for those species included in our study). This should be welcome news for nature conservationists, wind energy companies and policy-makers. However, our work is only a first step, as there may be potential influences of wind turbines on bird distribution during the breeding season. [source] Contributions of electrochemical oxidation to waste-water treatment: fundamentals and review of applicationsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2009Ángela Anglada Abstract OVERVIEW: This paper provides an overview of some fundamental aspects of electrochemical oxidation and gives updated information on the application of this technology to waste-water treatment. In recent years, electrochemical oxidation has gained increasing interest due to its outstanding technical characteristics for eliminating a wide variety of pollutants normally present in waste-waters such as refractory organic matter, nitrogen species and microorganisms. IMPACT: The strict disposal limits and health quality standards set by legislation may be met by applying electrochemical oxidation. However, treatment costs have to be cut down before full-scale application of this technology. Deployment of electrochemical oxidation in combination with other technologies and the use of renewable sources to power this process are two steps in this direction. APPLICATIONS: Effluents from landfill and a wide diversity of industrial effluents including the agro-industry, chemical, textile, tannery and food industry, have been effectively treated by this technology. Its high efficiency together with its disinfection capabilities makes electro-oxidation a suitable technology for water reuse programs. Copyright © 2009 Society of Chemical Industry [source] Advancement of renewables in Bangladesh and Thailand: Policy intervention and institutional settingsNATURAL RESOURCES FORUM, Issue 3 2006Sk Noim Uddin Abstract This article reviews and analyses the advancement of renewable sources of energy in Bangladesh and Thailand in terms of policy intervention and institutional settings. Since renewable forms of energy emit far smaller amounts of greenhouse gas compared with fossil fuels, their use should mitigate climate change impacts while contributing to the provision of energy services. The article turns first to a review of energy,environment trends and the potential for renewables in these two nations. It then discusses strategies for the advancement of renewables. It is argued that further significant efforts can be made towards the advancement of renewables in Bangladesh and Thailand. These two nations could also learn from the experience in industrialized nations and other developing nations with regard to requisite policy instruments and processes. A number of barriers remain to the advancement of renewables, especially in terms of policy arrangements, institutional settings, financing mechanisms and technologies. Resources, cooperation and learning are required in order to overcome such barriers and to foster the development of necessary policy measures. Implementation of the clean development mechanism (CDM) under the Kyoto Protocol, and replication and adaptation of effective strategies from other settings are possible avenues for this. [source] Can diabetes be cured by therapeutic cloning?PEDIATRIC DIABETES, Issue 2004Ahmi Ben-Yehudah Abstract:, With the increasing incidence of diabetes mellitus (DM), it is imperative to develop novel treatments. Stem cells offer the potential for use as renewable sources of glucose-responsive, insulin-secreting cells. However, developing a consistent protocol to enrich ,-cells is not a trivial issue. The question whether embryonic, fetal, or adult stem cells offer particular advantages as the starting material remains to be resolved experimentally. While somatic cell nuclear transfer avoids many of the problems associated with heterologous transplantation, the problem of autoimmune destruction of the ,-cells in type 1 DM might still remain. This review summarizes the innovative treatment strategies for DM and considers the possible advantages and problems. [source] Platform biochemicals for a biorenewable chemical industryTHE PLANT JOURNAL, Issue 4 2008Basil J. Nikolau Summary The chemical industry is currently reliant on a historically inexpensive, petroleum-based carbon feedstock that generates a small collection of platform chemicals from which highly efficient chemical conversions lead to the manufacture of a large variety of chemical products. Recently, a number of factors have coalesced to provide the impetus to explore alternative renewable sources of carbon. Here we discuss the potential impact on the chemical industry of shifting from non-renewable carbon sources to renewable carbon sources. This change to the manufacture of chemicals from biological carbon sources will provide an opportunity for the biological research community to contribute fundamental knowledge concerning carbon metabolism and its regulation. We discuss whether fundamental biological research into metabolic processes at a holistic level, made possible by completed genome sequences and integrated with detailed structural understanding of biocatalysts, can change the chemical industry from being dependent on fossil-carbon feedstocks to using biorenewable feedstocks. We illustrate this potential by discussing the prospect of building a platform technology based upon a concept of combinatorial biosynthesis, which would explore the enzymological flexibilities of polyketide biosynthesis. [source] Hydrogen Economy Options for AustraliaASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5-6 2004B. Mclellan Global concerns over the effects of current carbon dioxide (CO2) emissions have lead to extensive research on the use of hydrogen as a potential energy carrier for a lower emissions society. Hydrogen can be produced from both fossil and renewable energy sources. The hydrogen economy, in which hydrogen will be a carrier of energy from renewable sources, is a long-term development and any increasing demand for hydrogen will probably be covered initially from fossil sources. Technologies for hydrogen generation from renewable energies are being explored, whereas technologies for hydrogen production from fossil fuels have to a certain extent reached maturity. This paper addresses the major hydrogen generation processes and utilisation technology (fuel cells) currently available for the move from a fossil fuelsbased economy to a hydrogen economy. In particular, it illustrates the applicability of different hydrogen sources using Australia as an example. [source] Production of biodiesel: possibilities and challengesBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 1 2007Sulaiman Al-Zuhair Abstract Biodiesel, defined as monoalkyl fatty acid ester (preferentially methyl and ethyl esters), represents a promising alternative fuel for use in compression-ignition (diesel) engines. Biodiesel fuel comes from renewable sources as it is plant- not petroleum-derived and as such it is biodegradable and less toxic. In addition, relative to conventional diesel, its combustion products have reduced levels of particulates, carbon oxides, sulphur oxides and, under some conditions, nitrogen oxides. Enzymatic production of biodiesel has been proposed to overcome the drawbacks of the conventional chemically catalyzed processes. The main obstacle facing full exploitation of the enzyme, lipase, potential is its cost. Therefore, reuse of lipase is essential from the economic point of view, which can be achieved by using the lipase in immobilized form. In addition, immobilized lipase displays improved stability and activity. Common immobilization techniques include attachment to solid supports and entrapment within the matrix of a polymer. This article presents a comparison between conventional processes and enzymatic processes and different possible feedstocks for biodiesel production. In addition, possible ways to overcome the problems facing the use of lipase are described. © 2007 Society of Chemical Industry and John Wiley & Sons, Ltd [source] Industrial biotechnology: Tools and applicationsBIOTECHNOLOGY JOURNAL, Issue 12 2009Weng Lin Tang Abstract Industrial biotechnology involves the use of enzymes and microorganisms to produce value-added chemicals from renewable sources. Because of its association with reduced energy consumption, greenhouse gas emissions, and waste generation, industrial biotechnology is a rapidly growing field. Here we highlight a variety of important tools for industrial biotechnology, including protein engineering, metabolic engineering, synthetic biology, systems biology, and downstream processing. In addition, we show how these tools have been successfully applied in several case studies, including the production of 1, 3-propanediol, lactic acid, and biofuels. It is expected that industrial biotechnology will be increasingly adopted by chemical, pharmaceutical, food, and agricultural industries. [source] Innovations in the Development and Application of Edible Coatings for Fresh and Minimally Processed Fruits and VegetablesCOMPREHENSIVE REVIEWS IN FOOD SCIENCE AND FOOD SAFETY, Issue 3 2007Daniel Lin ABSTRACT:, One of the major growth segments in the food retail industry is fresh and minimally processed fruits and vegetables. This new market trend has thus increased the demands to the food industry for seeking new strategies to increase storability and shelf life and to enhance microbial safety of fresh produce. The technology of edible coatings has been considered as one of the potential approaches for meeting this demand. Edible coatings from renewable sources, including lipids, polysaccharides, and proteins, can function as barriers to water vapor, gases, and other solutes and also as carriers of many functional ingredients, such as antimicrobial and antioxidant agents, thus enhancing quality and extending shelf life of fresh and minimally processed fruits and vegetables. This review discusses the rationale of using edible coatings on fresh and minimally processed produce, the challenges in developing effective coatings that meet the specific criteria of fruits and vegetables, the recent advances in the development of coating technology, the analytical techniques for measuring some important coating functionalities, and future research needs for supporting a broad range of commercial applications. [source] | ||||||||||||||||||||||