Sample records for cellulose pour applications

  1. Synthesis and study of nano-structured cellulose acetate based materials for energy applications; Synthese et etude de materiaux nanostructures a base d'acetate de cellulose pour applications energetiques

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, F


    Nano-structured materials have unique properties (high exchange areas, containment effect) because of their very low characteristic dimensions. The elaboration way set up in this PhD work consists in applying the classical processes for the preparation of aerogel-like materials (combining sol-gel synthesis and CO{sub 2} supercritical extraction) to cellulosic polymers. This work is divided in four parts: a literature review, the presentation and the study of the chemical synthesis that leads to cellulose acetate-based aerogel, the characterizations (chemical, structural and thermal) of the elaborated nano-materials, and finally the study of the first carbons that were obtained after pyrolysis of the organic matrix. The formulations and the sol-gel protocol lead to chemical gels by crosslinking cellulose acetate using a poly-functional iso-cyanate. The dry materials obtained after solvent extraction with supercritical CO{sub 2} are nano-structured and mainly meso-porous. Correlations between chemical synthesis parameters (reagent concentrations, crosslinking rate and degree of polymerisation) and porous properties (density, porosity, pore size distribution) were highlighted thanks to structural characterizations. An ultra-porous reference aerogel, with a density equals to 0,245{sup -3} together with a meso-porous volume of 3,40 cm{sup 3}.g{sup -1} was elaborated. Once in granular shape, this material has a thermal conductivity of 0,029 W.m{sup -1}.K{sup -1}. In addition, carbon materials produced after pyrolysis of the organic matrix and after grinding are nano-structured and nano-porous, even if important structural modifications have occurred during the carbonization process. The elaborated materials are evaluated for applications in relation with energy such as thermal insulation (organic aerogels) but also for energy conversion and storage through electrochemical way (carbon aerogels). (author)

  2. Cellulose nanocrystals: synthesis, functional properties, and applications

    Directory of Open Access Journals (Sweden)

    George J


    Full Text Available Johnsy George, SN Sabapathi Food Engineering and Packaging Division, Defence Food Research Laboratory, Siddarthanagar, Mysore, Karnataka, India Abstract: Cellulose nanocrystals are unique nanomaterials derived from the most abundant and almost inexhaustible natural polymer, cellulose. These nanomaterials have received significant interest due to their mechanical, optical, chemical, and rheological properties. Cellulose nanocrystals primarily obtained from naturally occurring cellulose fibers are biodegradable and renewable in nature and hence they serve as a sustainable and environmentally friendly material for most applications. These nanocrystals are basically hydrophilic in nature; however, they can be surface functionalized to meet various challenging requirements, such as the development of high-performance nanocomposites, using hydrophobic polymer matrices. Considering the ever-increasing interdisciplinary research being carried out on cellulose nanocrystals, this review aims to collate the knowledge available about the sources, chemical structure, and physical and chemical isolation procedures, as well as describes the mechanical, optical, and rheological properties, of cellulose nanocrystals. Innovative applications in diverse fields such as biomedical engineering, material sciences, electronics, catalysis, etc, wherein these cellulose nanocrystals can be used, are highlighted. Keywords: sources of cellulose, mechanical properties, liquid crystalline nature, surface modification, nanocomposites 

  3. Electrospinning cellulose based nanofibers for sensor applications (United States)

    Nartker, Steven


    Bacterial pathogens have recently become a serious threat to the food and water supply. A biosensor based on an electrochemical immunoassay has been developed for detecting food borne pathogens, such as Escherichia coli (E. coli) O157:H7. These sensors consist of several materials including, cellulose, cellulose nitrate, polyaniline and glass fibers. The current sensors have not been optimized in terms of microscale architecture and materials. The major problem associated with the current sensors is the limited concentration range of pathogens that provides a linear response on the concentration conductivity chart. Electrospinning is a process that can be used to create a patterned fiber mat design that will increase the linear range and lower the detection limit of these sensors by improving the microscale architecture. Using the electrospinning process to produce novel mats of cellulose nitrate will offer improved surface area, and the cellulose nitrate can be treated to further improve chemical interactions required for sensor activity. The macro and micro architecture of the sensor is critical to the performance of the sensors. Electrospinning technology can be used to create patterned architectures of nanofibers that will enhance sensor performance. To date electrospinning of cellulose nitrate has not been performed and optimization of the electrospinning process will provide novel materials suitable for applications such as filtration and sensing. The goal of this research is to identify and elucidate the primary materials and process factors necessary to produce cellulose nitrate nanofibers using the electrospinning process that will improve the performance of biosensors. Cellulose nitrate is readily dissolved in common organic solvents such as acetone, tetrahydrofuran (THF) and N,N dimethylformamide (DMF). These solvents can be mixed with other latent solvents such as ethanol and other alcohols to provide a solvent system with good electrospinning behavior

  4. Cellulose nanocrystals: synthesis, functional properties, and applications


    George J.; Sabapathi SN


    Johnsy George, SN Sabapathi Food Engineering and Packaging Division, Defence Food Research Laboratory, Siddarthanagar, Mysore, Karnataka, India Abstract: Cellulose nanocrystals are unique nanomaterials derived from the most abundant and almost inexhaustible natural polymer, cellulose. These nanomaterials have received significant interest due to their mechanical, optical, chemical, and rheological properties. Cellulose nanocrystals primarily obtained from naturally occurring cellulose fibers...

  5. Fabrication of polyaniline/carboxymethyl cellulose/cellulose nanofibrous mats and their biosensing application

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Jiapeng, E-mail:; Pang, Zengyuan, E-mail:; Yang, Jie, E-mail:; Huang, Fenglin, E-mail:; Cai, Yibing, E-mail:; Wei, Qufu, E-mail:


    Graphical abstract: - Highlights: • PANI nanorods have been grown onto the surface of CMC/cellulose nanofibers for the fabrication of biosensor substrate material. • The proposed laccase biosensor exhibited a low detection limit and high sensitivity in the detection of catechol. • Hierarchical PANI/CMC/cellulose nanofibers are the promising material in the design of high-efficient biosensors. - Abstract: We report a facile approach to synthesizing and immobilizing polyaniline nanorods onto carboxymethyl cellulose (CMC)-modified cellulose nanofibers for their biosensing application. Firstly, the hierarchical PANI/CMC/cellulose nanofibers were fabricated by in situ polymerization of aniline on the CMC-modified cellulose nanofiber. Subsequently, the PANI/CMC/cellulose nanofibrous mat modified with laccase (Lac) was used as biosensor substrate material for the detection of catechol. PANI/CMC/cellulose nanofibers with highly conductive and three dimensional nanostructure were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectra (FT-IR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimum conditions, the Lac/PANI/CMC/cellulose/glassy carbon electrode (GCE) exhibited a fast response time (within 8 s), a linear response range from 0.497 μM to 2.27 mM with a high sensitivity and low detection limit of 0.374 μM (3σ). The developed biosensor also displayed good repeatability, reproducibility as well as selectivity. The results indicated that the composite mat has potential application in enzyme biosensors.

  6. Overview of Cellulose Nanomaterials, Their Capabilities and Applications (United States)

    Moon, Robert J.; Schueneman, Gregory T.; Simonsen, John


    Cellulose nanomaterials (CNs) are a new class of cellulose particles with properties and functionalities distinct from molecular cellulose and wood pulp, and as a result, they are being developed for applications that were once thought impossible for cellulosic materials. Momentum is growing in CN research and development, and commercialization in this field is happening because of the unique combination of characteristics (e.g., high mechanical properties, sustainability, and large-scale production potential) and utility across a broad spectrum of material applications (e.g. as an additive, self-sustaining structures, and template structures) that CNs offer. Despite the challenges typical for materials development, CN and near-CN production is ramping up with pilot scale to industry demonstration trials, and the first commercial products are starting to hit the marketplace. This review provides a broad overview of CNs and their capabilities that are enabling new application areas for cellulose-based materials.

  7. Fabrication of Piezoelectric Cellulose Paper and Audio Application

    Institute of Scientific and Technical Information of China (English)

    Jung-Hwan Kim; Sungryul Yun; Joo-Hyung Kim; Jaehwan Kim


    We report the fabrication process of piezoelectric cellulose paper and the enhancement method of its piezoelectric property.Stretching method with different wet-drawing ratios was introduced to increase the piezoelectric property of cellulose paper during regeneration process. It is observed that the Young's modulus and the piezoelectric charge constants are very dependent on the drawing ratio and the direction of nanofibrils of piezoelectric paper. Using the enhanced piezoelectric property, we prove that the flexible regenerated piezoelectric cellulose can be applied to the potential acoustic applications such as thin piezoelectric paper speaker.

  8. All-cellulose nanocomposite film made from bagasse cellulose nanofibers for food packaging application. (United States)

    Ghaderi, Moein; Mousavi, Mohammad; Yousefi, Hossein; Labbafi, Mohsen


    All-cellulose nanocomposite (ACNC) film was produced from sugarcane bagasse nanofibers using N,N-dimethylacetamide/lithium chloride solvent. The average diameter of bagasse fibers (14 μm) was downsized to 39 nm after disk grinding process. X-ray diffraction showed that apparent crystallinity and crystallite size decreased relatively to an increased duration of dissolution time. Thermogravimetric analysis confirmed that thermal stability of the ACNC was slightly less than that of the pure cellulose nanofiber sheet. Tensile strength of the fiber sheet, nanofiber sheet and ACNC prepared with 10 min dissolution time were 8, 101 and 140 MPa, respectively. Water vapor permeability (WVP) of the ACNC film increased relatively to an increased duration of dissolution time. ACNC can be considered as a multi-performance material with potential for application in cellulose-based food packaging owing to its promising properties (tough, bio-based, biodegradable and acceptable levels of WVP).

  9. Soudage des aciers pour application mécanique

    CERN Document Server

    Deveaux, Dominique


    Ce guide détermine les bonnes pratiques pour comprendre les risques d’une forme d’assemblage multimatériaux : celui par soudage de nuances à forte teneur en carbone avec des éléments en acier de construction. Dans un premier temps, le rapport passe en revue l’examen des avaries sur des assemblages soudés pour l’application mécanique mettant en cause les aciers. Fissuration par fatigue, rupture fragile, rupture ductile, fissuration à chaud ou à froid sont autant de causes qui seront analysées. Dans un deuxième temps, il se concentre sur la conception des joints soudés. Du choix des nuances à la tenue vis-à-vis de la rupture fragile en passant par l’analyse en fatigue des assemblages soudés, c’est l’ensemble de la problématique qui est pris en compte.

  10. Cellulose nanowhiskers and nanofibers from biomass for composite applications (United States)

    Wang, Tao


    Biological nanocomposites such as plant cell wall exhibit high mechanical properties at a light weight. The secret of the rigidity and strength of the cell wall lies in its main structural component -- cellulose. Native cellulose exists as highly-ordered microfibrils, which are just a few nanometers wide and have been found to be stiffer than many synthetic fibers. In the quest for sustainable development around the world, using cellulose microfibrils from plant materials as renewable alternatives to conventional reinforcement materials such as glass fibers and carbon fibers is generating particular interest. In this research, by mechanical disintegration and by controlled chemical hydrolysis, both cellulose nanofibers and nanowhiskers were extracted from the cell wall of an agricultural waste, wheat straw. The reinforcement performances of the two nanofillers were then studied and compared using the water-soluble polyvinyl alcohol (PVOH) as a matrix material. It was found that while both of these nanofillers could impart higher stiffness to the polymer, the nanofibers from biomass were more effective in composite reinforcement than the cellulose crystals thanks to their large aspect ratio and their ability to form interconnected network structures through hydrogen bonding. One of the biggest challenges in the development of cellulose nanocomposites is achieving good dispersion. Because of the high density of hydroxyl groups on the surface of cellulose, it remains a difficult task to disperse cellulose nanofibers in many commonly used polymer matrices. The present work addresses this issue by developing a water-based route taking advantage of polymer colloidal suspensions. Combining cellulose nanofibers with one of the most important biopolymers, poly(lactic acid) (PLA), we have prepared nanocomposites with excellent fiber dispersion and improved modulus and strength. The bio-based nanocomposites have a great potential to serve as light-weight structural materials

  11. Production of nanocrystalline cellulose from lignocellulosic biomass: technology and applications. (United States)

    Brinchi, L; Cotana, F; Fortunati, E; Kenny, J M


    The use of renewables materials for industrial applications is becoming impellent due to the increasing demand of alternatives to scarce and unrenewable petroleum supplies. In this regard, nanocrystalline cellulose, NCC, derived from cellulose, the most abundant biopolymer, is one of the most promising materials. NCC has unique features, interesting for the development of new materials: the abundance of the source cellulose, its renewability and environmentally benign nature, its mechanical properties and its nano-scaled dimensions open a wide range of possible properties to be discovered. One of the most promising uses of NCC is in polymer matrix nanocomposites, because it can provide a significant reinforcement. This review provides an overview on this emerging nanomaterial, focusing on extraction procedures, especially from lignocellulosic biomass, and on technological developments and applications of NCC-based materials. Challenges and future opportunities of NCC-based materials will be are discussed as well as obstacles remaining for their large use.

  12. Zinc impregnated cellulose nanocomposites: Synthesis, characterization and applications (United States)

    Ali, Attarad; Ambreen, Sidra; Maqbool, Qaisar; Naz, Sania; Shams, Muhammad Fahad; Ahmad, Madiha; Phull, Abdul Rehman; Zia, Muhammad


    Nanocomposite materials have broad applicability due to synergistic effect of combined components. In present investigation, cellulose isolated from citrus peel waste is used as a supporting material; impregnation of zinc oxide nanoparticles via co-precipitation method. The characterization of nano composite is carried out through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and Thermo-gravimetric analysis (TGA) resulting less than 10 μm cellulose fiber and approx. 50 nm ZnO NPs. Zinc oxide impregnated cellulose (ZnO-Cel) exhibited significant bacterial devastation property when compared to ZnO NPs or Cellulose via disc diffusion and colony forming unit methods. In addition, the ZnO-Cel exhibited significant total antioxidant, and minor DPPH free radical scavenging and total reducing power activities. The nano composite also showed time dependent increase in photocatalytic by effectively degrading methylene blue dye up to 69.5% under sunlight irradiation within 90 min. The results suggest effective utilization of cellulose obtained from citrus waste and synthesis of pharmacologically important nano-composites that can be exploited in wound dressing; defence against microbial attack and healing due to antioxidative property, furthermore can also be used for waste water treatment.

  13. Fabrication of cellulose nanofiber transparent films for IT applications (United States)

    Zhai, Lindong; Song, Sangho; Kim, Jeong Woong; Li, Yaguang; Kim, Jaehwan


    One of the abundant renewable biomaterials in the world - cellulose is produced from plants forming micro-fibrils which in turn aggregate of form cellulose fibers. These fibers size can be disintegrated from micro-fibrils to nanofibers by physical and chemical methods. Cellulose nanofibers (CNF) can be a new building block of renewable smart materials. The CNF has excellent mechanical strength, dimensional stability, thermal stability and good optical properties on top of their renewable behavior. This paper reports CNF transparent films made by CNF extracted by the physical method: a high pressure physical, so called aqueous counter collision method. Natural behaviors, extraction and film formation of CNF are explained and their characteristics are illustrated, which is suit for IT applications.

  14. Conception et calibration d'un sonoreacteur pour l'oxydation de la cellulose par le systeme TEMPO/NaOCl/NaBr (United States)

    Paquin, Michel

    Avec le contexte economique actuel dans le domaine des pates et papiers au Canada, l'industrie se doit de diversifier ses produits mis en marche. La fermeture de plus de 20 usines depuis 2005, une baisse du PIB de l'industrie de 1,4 milliard CAD entre 1999--2008, une baisse de la demande de 2,4 %, une diminution du prix de la pate de 20,9 % depuis juillet 2009. La delocalisation du secteur vers l'Asie et l'hemisphere sud sont autant de raisons pour laquelle l'industrie se doit d'etre a l'avant plan de nouvelle technologie a base de fibre de bois. Pour augmenter leur rentabilite, l'industrie se doit de diversifier ses produits dans d'autres secteurs que le simple fabricant de papier impression-ecriture. Sa diversification passe par l'elaboration de nouveaux papiers a valeur ajoutee (papier conducteur, papier bioactif, etc.), par l'utilisation de la biomasse forestiere pour la production d'energie, par l'utilisation de la biomasse forestiere pour l'elaboration d'une plateforme de chimie verte, par l'utilisation de la lignine pour le developpement de polymeres et par l'utilisation de la fibre cellulosique pour la fabrication de nanomateriaux. La fabrication de nanofibrille de cellulose peut devenir un des produits qui servira a diversifier la production des usines de pates et papiers. Les nanofibrilles de cellulose possedent des proprietes mecaniques et chimiques exceptionnelles. Les nanofibrilles de cellulose sont fabriquees a partir d'une oxydation selective de la pate kraft de feuillu avec le systeme TEMPO-NaOCl-NaBr. L'oxydation selective de l'alcool primaire en C6 du monomere de glucose sous forme de carboxylates engendre une modification chimique de la cellulose qui accroit l'hydrophilicite des fibrilles. Suite a cette oxydation, nous devons effectuer une desintegration mecanique de la fibre kraft de feuillu oxydee pour separer les fibrilles. Le processus d'oxydation de la fibre par le systeme TEMPO-NaOCl-NaBr et sa defibrillation par la suite engendre une

  15. New application of crystalline cellulose in rubber composites (United States)

    Bai, Wen

    Rubber without reinforcement has limited applications. The strength of reinforced rubber composites can be ten times stronger than that of unreinforced rubbers. Therefore, rubber composites are widely used in various applications ranging from automobile tires to seals, valves, and gaskets because of their excellent mechanical elastic properties. Silica and carbon black are the two most commonly used reinforcing materials in rubber tires. They are derived from non-renewable materials and are expensive. Silica also contributes to a large amount of ash when used tires are disposed of by incineration. There is a need for a new reinforcing filler that is inexpensive, renewable and easily disposable. Cellulose is the most abundant natural polymer. Native cellulose includes crystalline regions and amorphous regions. Crystalline cellulose can be obtained by removing the amorphous regions with the acid hydrolysis of cellulose because the amorphous cellulose can be hydrolyzed faster than crystalline cellulose. We recently discovered that the partial replacement of silica with microcrystalline cellulose (MCC) provided numerous benefits: (1) low energy consumption for compounding, (2) good processability, (3) strong tensile properties, (4) good heat resistance, and (5) potential for good fuel efficiency in the application of rubber tires. Strong bonding between fillers and a rubber matrix is essential for imparting rubber composites with the desired properties for many specific applications. The bonding between hydrophilic MCC and the hydrophobic rubber matrix is weak and can be improved by addition of a coupling agent or surface modifications of MCC. In this study, MCC was surface-modified with acryloyl chloride or alkenyl ketene dimer (AnKD) to form acrylated MCC (A-MCC) and AnKD-modified MCC (AnKD-MCC). The surface modifications of MCC did not change the integrity and mechanical properties of MCC, but provided functional groups that were able to form covalent linkages with

  16. New applications for cellulose nanofibers: Rheological challenges (United States)

    Nazari-Nasrabad, Behzad

    Cellulose nanofibers (CNF) are an exciting new renewable material produced from wood fibers. Even at low solids content, CNF-water suspensions have a complex rheology that includes extreme shear-thinning as well as viscoelastic properties and a yield stress. In the rheology of CNF suspensions, the measurement method may influence the results due to wall-slippage, but it is unclear how the behavior near walls influences the measurement method and what process equipment can manipulate this material. Parallel-plate and vane geometries were utilized to compare yielding and flow of CNF suspensions obtained by steady-state shear and oscillatory rheological measurements. Four different methods were compared as techniques to obtain a yield stress. The results are compared to pressure driven flow in a tube. Cone and plate geometries were found to lead to sample ejection at low shear rates: floc-floc interactions can explain this ejection. The suspensions violated the Cox-Merz rule in a significant manner as a sign of containing weak gel structures and the formation of a water-rich layer near the solid boundaries. For suspensions lower than 3% solids, the yield stress measured with different procedures were within 20% of each other, but for high solids suspensions, differences among the methods could be as large as 100%; the water-rich layer formation likely is the cause of these results. Oscillatory methods are suggested as a technique to obtain yield stress values. The pressure driven flow results were consistent with the power-law line fitted to the parallel-plate geometry data from steady shear. The capability of the extrusion process was investigated for pumping CNF suspensions through different dies. The extrusion process resulted in acceptable pumping rates which was in good agreement with the mathematical model. However, attributable to the extreme shear-thinning behavior of CNF, the pressure counter-flow dominates the drag flow along the screw channel and does not

  17. A review on chitosan-cellulose blends and nanocellulose reinforced chitosan biocomposites: Properties and their applications. (United States)

    H P S, Abdul Khalil; Saurabh, Chaturbhuj K; A S, Adnan; Nurul Fazita, M R; Syakir, M I; Davoudpour, Y; Rafatullah, M; Abdullah, C K; M Haafiz, M K; Dungani, R


    Chitin is one of the most abundant natural polymers in world and it is used for the production of chitosan by deacetylation. Chitosan is antibacterial in nature, non-toxic, and biodegradable thus it can be used for the production of biodegradable film which is a green alternative to commercially available synthetic counterparts. However, their poor mechanical and thermal properties restricted its wide spread applications. Chitosan is highly compatible with other biopolymers thus its blending with cellulose and/or incorporation of nanofiber isolated from cellulose namely cellulose nanofiber and cellulose nanowhiskers are generally useful. Cellulosic fibers in nano scale are attractive reinforcement in chitosan to produce environmental friendly composite films with improved physical properties. Thus chitosan based composites have wide applicability and potential in the field of biomedical, packaging and water treatment. This review summarises properties and preparation procedure of chitosan-cellulose blends and nano size cellulose reinforcement in chitosan bionanocomposites for different applications.

  18. Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications

    Directory of Open Access Journals (Sweden)

    Asif Khan


    Full Text Available We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active paper and its hybrid composites such as blends or coatings with synthetic polymers, biopolymers, carbon nanotubes, chitosan, and metal oxides, are explained. In addition, the integration of cellulose electro-active paper is highlighted to form various functional devices including but not limited to bending actuators, flexible speaker, strain sensors, energy harvesting transducers, biosensors, chemical sensors and transistors for electronic applications. The frontiers in cellulose paper devices are reviewed together with the strategies and perspectives of cellulose electro-active paper and cellulose nanocomposite research and applications.

  19. Recent Progress on Cellulose-Based Electro-Active Paper, Its Hybrid Nanocomposites and Applications (United States)

    Khan, Asif; Abas, Zafar; Kim, Heung Soo; Kim, Jaehwan


    We report on the recent progress and development of research into cellulose-based electro-active paper for bending actuators, bioelectronics devices, and electromechanical transducers. The cellulose electro-active paper is characterized in terms of its biodegradability, chirality, ample chemically modifying capacity, light weight, actuation capability, and ability to form hybrid nanocomposites. The mechanical, electrical, and chemical characterizations of the cellulose-based electro-active paper and its hybrid composites such as blends or coatings with synthetic polymers, biopolymers, carbon nanotubes, chitosan, and metal oxides, are explained. In addition, the integration of cellulose electro-active paper is highlighted to form various functional devices including but not limited to bending actuators, flexible speaker, strain sensors, energy harvesting transducers, biosensors, chemical sensors and transistors for electronic applications. The frontiers in cellulose paper devices are reviewed together with the strategies and perspectives of cellulose electro-active paper and cellulose nanocomposite research and applications. PMID:27472335

  20. Nanocrystalline cellulose from coir fiber: preparation, properties, and applications (United States)

    Nanocrystalline cellulose derived from various botanical sources offers unique and potentially useful characteristics. In principle, any cellulosic material can be considered as a potential source of a nanocrystalline material, including crops, crop residues, and agroindustrial wastes. Because of t...

  1. Application du système immunitaire artificiel pour la reconnaissance des chiffres


    Khelil, Hiba; Benyettou, Abdelkader; Belaïd, Abdel


    International audience; La reconnaissance automatique de l'écriture occupe un espace important dans la recherche scientifique car elle offre une facilité d'utilisation dans différents domaines d'application : domaine bancaire, postal, le e-commerce... De nombreuses méthodes ont été utilisées pour la reconnaissance d'écriture, dans cet article nous présenterons des méthodes inspirées du système immunitaire naturel que nous appliquerons pour la reconnaissance des chiffres.Des résultats satisfai...


    Directory of Open Access Journals (Sweden)

    Shingo Yokota


    Full Text Available Specific and strong cellulose-binding characteristics were utilized for promoting retention of additives in contaminated papermaking systems. Cellulose-binding domain (CBD of cellulase derived from Trichoderma viride was separated by digestion with papain, and then introduced into anionic polyacrylamide (A-PAM through a condensation reaction using water-soluble carbodiimide. The CBD-modified A-PAM (CBD-A-PAM showed good retention on pulp fibers, resulting in high tensile strength paper sheets. The effect remained almost unchanged in the presence of model interfering substances such as ligninsulfonate and Ca2+ ions, whereas commercial cationic paper-strengthening polymer became ineffective. The cellulose-binding force of CBD was quantitatively determined by atomic force microscopy (AFM in the liquid state. Histidine-tagged CBD protein was obtained using Escherichia coli via an expression of CBD derived from Cellulomonas fimi, and immobilized on a gold-coated AFM probe. A strong attractive force was detected only at a CBD/cellulose interface, even when Ca2+ ions were present in high concentration. Direct estimation of CBD affinity for cellulose substrate by AFM would provide significant information on the interfacial interactions useful for the functional design of papermaking additives.

  3. Characterization and Possible Applications of Some Novel Cellulose Derivatives and Composites

    Institute of Scientific and Technical Information of China (English)

    P. Zugenmaier


    @@ 1Introduction Cellulose is a naturally occurring linear chain of 1-4 linked β-D-glucopyranose and exhibits great chemical variability and potentials in applications. The cell walls of all plants contain fibers of cellulose. It has long been harvested as commercial fibers from cotton, flax, hemp, sisal, jute and ramie or as wood, which is a common building material or used as a source for purified cellulose. Wood represents a composite material with cellulose as major part combined in excellent form with lignin and hemicelluloses creating a unique high strength and durable material and recently came again into focus as renewable energy resource.

  4. Nanomatériaux luminescent pour des applications en diagnostics



    The work of this thesis titled “Luminescent Nanomaterials for diagnostic applications” is synthesis, characterization and bioimaging applications of nanomaterials. Silicon nanoparticles were synthesized and modified with different functional groups such as amino, carboxylate, sugar and platinum(II) complex on the surface, and applies for cellular imaging at HeLa. Moreover, the assembly platinum(II) complexes modified silicon nanoparticles exhibit an interesting aggregation induced emission (A...

  5. Composite Risers for Deepwater Applications Risers composites pour applications en mer profonde

    Directory of Open Access Journals (Sweden)

    Metivaud G.


    Full Text Available This paper is devoted to the high performance composite tubes developed by the Institut Français du Pétrole (IFP and Aerospatiale for deepwater risers applications. The design principles of the tubes are first presented, along with results of preliminary work carried out as part of the initial feasibility study. Applications of composite tubes to drilling riser Kill and Choke lines and to TLP production risers, both of which have been studied in detail, are then described. Technical and operational advantages obtained from such applications are discussed. Cet article présente les travaux réalisés par l'Institut Français du Pétrole et l'Aerospatiale dans le domaine des tubes composites haute performance pour les applications aux liaisons fond-surface de forage et de production en mer profonde. Les matériaux composites avancés sont une classe de matériaux très particulière, présentant à la fois des caractéristiques mécaniques élevées et une densité spécifique faible. Ils sont utilisés principalement par les industries de l'aéronautique et de l'espace, mais l'industrie pétrolière en mer profonde est un secteur où ils peuvent trouver dans l'avenir des applications très intéressantes, notamment les tubes de risers. Les tubes de risers pétroliers en mer présentent en effet une gamme de spécifications élevées (diamètres, pression, traction, fatigue dans un environnement sévère et leur poids suspendu peut pénaliser fortement les systèmes de forage ou de production par grande profondeur d'eau. Un premier concept de tube composite haute performance a été développé par IFP et Aerospatiale au début des années 1980 ; sa partie courante, réalisée par enroulement filamentaire de fibres de verre R ou de fibres de carbone, et son système d'embout ont été soumis à une série d'essais mécaniques (pression interne jusqu'à 105 MPa, traction supérieure à 1 000 kN pour un diamètre nominal de 0,1 m, millions de

  6. NooJ, un outil TAL pour l'enseignement des langues. Application pour l'étude de la morphologie lexicale en FLE

    Directory of Open Access Journals (Sweden)

    Max Silberztein


    Full Text Available NooJ est un système de traitement de corpus – reprenant et améliorant les fonctionnalités d'INTEX – conçu pour l'enseignement des langues et de la linguistique. NooJ intègre des outils de traitement automatique du langage qui offrent à l'enseignant des possibilités de traiter un corpus, et des procédures de recherche, de test, et d'entraînement pour l'étudiant. Nous présentons ici un exemple d'application de NooJ à l'enseignement du français langue étrangère, qui reprend quelques activités sur l'étude de la morphologie lexicale.

  7. Application of ethyl cellulose, microcrystalline cellulose and octadecanol for wax based floating solid dispersion pellets. (United States)

    Yan, Hong-Xiang; Zhang, Shuang-Shuang; He, Jian-Hua; Liu, Jian-Ping


    The present study aimed to develop and optimize the wax based floating sustained-release dispersion pellets for a weakly acidic hydrophilic drug protocatechuic acid to achieve prolonged gastric residence time and improved bioavailability. This low-density drug delivery system consisted of octadecanol/microcrystalline cellulose mixture matrix pellet cores prepared by extrusion-spheronization technique, coated with drug/ethyl cellulose 100cp solid dispersion using single-step fluid-bed coating method. The formulation-optimized pellets could maintain excellent floating state without lag time and sustain the drug release efficiently for 12h based on non-Fickian transport mechanism. Observed by SEM, the optimized pellet was the dispersion-layered spherical structure containing a compact inner core. DSC, XRD and FTIR analysis revealed drug was uniformly dispersed in the amorphous molecule form and had no significant physicochemical interactions with the polymer dispersion carrier. The stability study of the resultant pellets further proved the rationality and integrity of the developed formulation.

  8. Development of Cellulose-Based, Nanostructured, Conductive Paper for Biomolecular Extraction and Energy Storage Applications


    Razaq, Aamir


    Conductive paper materials consisting of conductive polymers and cellulose are promising for high-tech applications (energy storage and biosciences) due to outstanding aspects of environmental friendliness, mechanical flexibility, electrical conductivity and efficient electroactive behavior. Recently, a conductive composite paper material was developed by covering the individual nanofibers of cellulose from the green algae Cladophora with a polypyrrole (PPy) layer. The PPy-Cladophora cellulos...

  9. Synthesis of cellulose nanofiber composites for mechanical reinforcement and other advanced applications (United States)

    Xu, Xuezhu

    Cellulose nanofibers from bioresources have attracted intensive research interest in recent years due to their unique combination of properties including high strength and modulus, low density, biocompatibility/biodegradability and rich surface chemistry for functionalization. The nanofibers have been widely studied as nanoreinforcements in polymer nanocomposites; while the nanocomposite research is still very active, new research directions of using the nanofibers for hydrogels/aerogels, template for nanoparticle synthesis, scaffold, carbon materials, nanopaper, etc. have emerged. In this Ph.D. thesis, fundamental studies and application developments are performed on three types of cellulose nanofibers, i.e. cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs) and bacterial cellulose (BC). First CNCs and CNFs are systematically compared in terms of their effects on the mechanical properties, crystallization and failure behavior of the nanocomposites, which provides a guideline for the design of cellulose nanofiber reinforced composites. Second, CNFs and BC are used to develop core-shell carbon fibers and flexible carbon aerogels for energy storage applications. This part is focused on developing nanocarbon materials with multi-scale features. Lastly, hybrid CNC/CNF nanopaper with superior optical, mechanical, and electrical properties is developed and its application is demonstrated on a LED device.

  10. Nanocrystalline cellulose from aspen kraft pulp and its application in deinked pulp. (United States)

    Xu, Qinghua; Gao, Yang; Qin, Menghua; Wu, Kaili; Fu, Yingjuan; Zhao, Jian


    Nanocrystalline cellulose (NCC) isolated from bleached aspen kraft pulp was characterized, and its application as pulp strengthening additive and retention aid was investigated. Results showed that NCC with high crystallinity of more than 80% can be obtained using 64 wt% sulfuric acid. The structure of nanocrystalline cellulose is parallelepiped rod-like, and their cross-sectional dimension is in the nanometer range with a high aspect ratio. The formation of microparticle retention systems during the application of NCC together with cationic polyacrylamide and cationic starch in deinked pulp was able to further improve pulp retention and strength properties without negative influence on the drainage.

  11. Applications of functionalized and nanoparticle-modified nanocrystalline cellulose. (United States)

    Lam, Edmond; Male, Keith B; Chong, Jonathan H; Leung, Alfred C W; Luong, John H T


    Nanocrystalline cellulose (NCC), a rod-shaped nanoscale material with exceptional strength and physicochemical properties, can be prepared from inexpensive renewable biomass. Besides its potential use as a reinforcing agent for industrial biocomposites, pristine NCC exhibits low toxicity and poses no serious environmental concerns, providing impetus for its use in bioapplications. Here, we review recent developments in the use of modified NCC for emerging bioapplications, specifically enzyme immobilization, antimicrobial and medical materials, green catalysis, biosensing and controlled drug delivery. We focus on the modification of NCC with chemical functionalities and inorganic nanoparticles, reviewing practical considerations such as reusability, toxicity and scale-up capability.

  12. Un profil d'application de LOM pour les Serious Games


    Marfisi-Schottman, Iza; George, Sébastien; Tarpin-Bernard, Franck


    Les Serious Games (SG), que l'on peut traduire par " jeux éducatifs ", sont des environnements pertinents dans de nombreux domaines de formation, mais qui posent aussi des problèmes liés à leur création fastidieuse, coûteuse en moyens et en temps. Cette conception risquée encourage les auteurs à capitaliser et partager tout ou partie de leurs SG. Ils ont donc besoin d'une méthode pour les décrire. Dans cet article, nous proposons un nouveau profil d'application du schéma de métadonnées LOM (L...

  13. Micro-Nanostructured Polyaniline Assembled in Cellulose Matrix via Interfacial Polymerization for Applications in Nerve Regeneration. (United States)

    Xu, Dingfeng; Fan, Lin; Gao, Lingfeng; Xiong, Yan; Wang, Yanfeng; Ye, Qifa; Yu, Aixi; Dai, Honglian; Yin, Yixia; Cai, Jie; Zhang, Lina


    Conducting polymers have emerged as frontrunners to be alternatives for nerve regeneration, showing a possibility of the application of polyaniline (PANI) as the nerve guidance conduit. In the present work, the cellulose hydrogel was used as template to in situ synthesize PANI via the limited interfacial polymerization method, leading to one conductive side in the polymer. PANI sub-micrometer dendritic particles with mean diameter of ∼300 nm consisting of the PANI nanofibers and nanoparticles were uniformly assembled into the cellulose matrix. The hydrophobic PANI nanoparticles were immobilized in the hydrophilic cellulose via the phytic acid as "bridge" at presence of water through hydrogen bonding interaction. The PANI/cellulose composite hydrogels exhibited good mechanical properties and biocompatibility as well as excellent guiding capacity for the sciatic nerve regeneration of adult Sprague-Dawley rats without any extra treatment. On the basis of the fact that the pure cellulose hydrogel was an inert material for the neural repair, PANI played an indispensable role on the peripheral nerve regeneration. The hierarchical micro-nanostructure and electrical conductivity of PANI could remarkably induce the adhesion and guiding extension of neurons, showing its great potential in biomedical materials.

  14. Screening of the effective cellulose-degradable strain and its application in the production of cellulose bioethanol

    Institute of Scientific and Technical Information of China (English)

    Peng-fei Gao; Dai-di Fan; Pei Ma; Yan-e Luo; Xiao-xuan Ma; Chen-hui Zhu; Jun-feng Hui


    Strains from the cellulose-containing environment were collected. Primary screening(by filter-paper Hutchison solid culture medium and sodium carboxymethylcellulose solid culture medium) and reelection(by filter-paper inorganic salt culture medium and sodium carboxymethylcellulosc Congo red coltnre medium) indicated that five strains obtained were best suited for high performance cellulose degradation. Determination of sodium carboxymethylcellulose activity(CMCA) and filter paper activity(FPA) was accomplished for each of the five. The strongest of the five in CMCA and FPA was applied to the production of cellulose bioethanol by separate hydrolysis and fermentation(SHF) and simultaneous saccharification and fermentation(SSF) respectively.

  15. A multipurpose natural and renewable polymer in medical applications: Bacterial cellulose. (United States)

    de Oliveira Barud, Hélida Gomes; da Silva, Robson Rosa; da Silva Barud, Hernane; Tercjak, Agnieszka; Gutierrez, Junkal; Lustri, Wilton Rogério; de Oliveira, Osmir Batista; Ribeiro, Sidney J L


    Bacterial cellulose (BC) produced by some bacteria, among them Gluconacetobacter xylinum, which secrets an abundant 3D networks fibrils, represents an interesting emerging biocompatible nanomaterial. Since its discovery BC has shown tremendous potential in a wide range of biomedical applications, such as artificial skin, artificial blood vessels and microvessels, wound dressing, among others. BC can be easily manipulated to improve its properties and/or functionalities resulting in several BC based nanocomposites. As example BC/collagen, BC/gelatin, BC/Fibroin, BC/Chitosan, etc. Thus, the aim of this review is to discuss about the applicability in biomedicine by demonstrating a variety of forms of this biopolymer highlighting in detail some qualities of bacterial cellulose. Therefore, various biomedical applications ranging from implants and scaffolds, carriers for drug delivery, wound-dressing materials, etc. that were reported until date will be presented.

  16. Rheological study of cellulose dissolved in aqueous ZnCl2 : Regenerated cellulosic fibres for textile applications


    Ulfstad, Louise


    The most known regenerated cellulosic fiber is viscose, produced in a wet spinning process, but due to cost and environmental issues other processes have been developed. Lyocell fibers, produced in air-gap spinning, have superior dry and wet strenght and a lower environmental impact compared to viscose. Research in different cellulose solvent has increased significantly tha last decadess, due to an increased cotton price and a decreased paper production, providing more wood pulp to production...

  17. Screening of the effective cellulose-degradable strain and its application in the production of cellulose bioethanol

    Institute of Scientific and Technical Information of China (English)


    Strains from the cellulose-containing environment were collected. Primary screening(by filter-paper Hutchison solid culture medium and sodium carboxymethylcellulose solid culture medium) and reelection(by filter-paper inorganic salt culture medium and sodium carboxymethylcellulose Congo red culture medium) indicated that five strains obtained were best suited for high performance cellulose degradation. Determination of sodium carboxymethylcellulose activity(CMCA) and filter paper activity(FPA) was accomplis...

  18. Cellulose is not just cellulose

    DEFF Research Database (Denmark)

    Hidayat, Budi Juliman; Felby, Claus; Johansen, Katja Salomon


    or enzymatic hydrolysis of plant cell walls is carried out simultaneously with the application of shear stress, plant cells such as fibers or tracheids break at their dislocations. At present it is not known whether specific carbohydrate binding modules (CBMs) and/or cellulases preferentially access cellulose......Most secondary plant cell walls contain irregular regions known as dislocations or slip planes. Under industrial biorefining conditions dislocations have recently been shown to play a key role during the initial phase of the enzymatic hydrolysis of cellulose in plant cell walls. In this review we...... are not regions where free cellulose ends are more abundant than in the bulk cell wall. In more severe cases cracks between fibrils form at dislocations and it is possible that the increased accessibility that these cracks give is the reason why hydrolysis of cellulose starts at these locations. If acid...

  19. Optimisation multi-physique d'une chaîne d'actionnement pour application automobile


    ROBERT, Florent; Dufour, Laurent; Gutfrind, Christophe; Liebart, Vincent; BENSETTI, Mohamed; Dessante, Philippe


    International audience; Une chaîne d'actionnement est constituée de la mise en cascade de systèmes de transformation et de maîtrise d'énergie, afin d'obtenir un mouvement mécanique contrôlé pour une application donnée. Ce genre de structure comporte fréquemment des filtrages, un convertisseur d'électronique de puissance, un actionneur et une transmission mécanique, et ce pour différents niveaux de puissance. Dans cet article, nous nous intéressons à une procédure de dimensionnement simultané ...

  20. Preparation of Cellulose Nanofibrils from Bamboo Pulp by Mechanical Defibrillation for Their Applications in Biodegradable Composites. (United States)

    Guimarães, Mario; Botaro, Vagner Roberto; Novack, Kátia Monteiro; Neto, Wilson Pires Flauzino; Mendes, Lourival Marin; Tonoli, Gustavo H D


    There is a growing interest in cellulose nanofibrils from renewable sources for various industrial applications. However, there is a lack of information on cellulose arising from bamboo pulps. Nanofibrils from refined bamboo pulps, including bleached, unbleached, and unrefined/unbleached, were obtained by mechanical defibrillation for use in biodegradable composites. The influence of industrial processes, such as pulping and refining of unbleached pulps, as well as of alkali pretreatments and bleaching of refined pulps, on the chemical composition of the samples was analyzed. Morphological, structural, thermal, optical and viscometric properties were investigated as a function of the number of passages of refined/bleached suspensions through a defibrillator. For the unbleached suspensions, the effects of refining and bleaching on the properties of nanofibrils were evaluated, fixing the number of passages through the defibrillator. Microscopic studies demonstrated that nanoscale cellulose fibers were obtained from both pulps, with a higher yield for the refined/bleached and refined/unbleached pulp, at the expense of the unbleached/unrefined pulps. The study showed that, in addition to the effectiveness of the pre-treatments, there was an increase in the production efficiency of nanofibrils, as well as in the transparency of the bleached suspensions, while viscosity, thermal stability and crystallinity had reduced levels as the number of passages through the defibrillator increased, showing a gradual improvement in the transition from the micro- to the nano-scale. The present study contributed to the different methods that are available for the production of bamboo cellulose nanofibrils, which can be used in the production of biodegradable composites for various applications.

  1. Biomimetic design of a bacterial cellulose/hydroxyapatite nanocomposite for bone healing applications

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, Kristen A., E-mail: [Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24060 (United States); School of Biomedical Engineering Sciences, Virginia Tech, Blacksburg, VA 24060 (United States); LeBlanc, Jill M.; Sheets, Kevin T.; Fox, Robert W. [Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24060 (United States); Gatenholm, Paul [Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24060 (United States); School of Biomedical Engineering Sciences, Virginia Tech, Blacksburg, VA 24060 (United States)


    This study describes the design and synthesis of bacterial cellulose/hydroxyapatite nanocomposites for bone healing applications using a biomimetic approach. Bacterial cellulose (BC) with various surface morphologies (pellicles and tubes) was negatively charged by the adsorption of carboxymethyl cellulose (CMC) to initiate nucleation of calcium-deficient hydroxyapatite (cdHAp). The cdHAp was grown in vitro via dynamic simulated body fluid (SBF) treatments over a one week period. Characterization of the mineralized samples was done with X-ray Photoelectron Spectroscopy (XPS) and Field Emission Scanning Electron Microscopy (FESEM) with Energy Dispersive Spectroscopy (EDS). The amount of cdHAp observed varied among different samples. XPS demonstrated that the atomic presence of calcium and phosphorus ranged from 0.44 at.% to 7.71 at.% Ca and 0.27 at.% to 11.18 at.% P. The Ca/P overall ratio ranged from 1.22 to 1.92. FESEM images showed that the cdHAp crystal size increased with increasing nanocellulose fibril density. To determine the viability of the scaffolds in vitro, the morphology and differentiation of osteoprogenitor cells was analyzed using fluorescence microscopy and alkaline phosphatase gene expression. The presence of cdHAp crystals on BC surfaces resulted in increased cell attachment.

  2. Preparation and Characterization of Jute Cellulose Crystals-Reinforced Poly(L-lactic acid Biocomposite for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Mohammed Mizanur Rahman


    Full Text Available Crystalline cellulose was extracted from jute by hydrolysis with 40% H2SO4 to get mixture of micro/nanocrystals. Scanning electron microscope (SEM showed the microcrystalline structure of cellulose and XRD indicated the Iβ polymorph of cellulose. Biodegradable composites were prepared using crystalline cellulose (CC of jute as the reinforcement (3–15% and poly(lactic acid (PLA as a matrix by extrusion and hot press method. CC was cellulose derived from mercerized and bleached jute fiber by acid hydrolysis to remove the amorphous regions. FT-IR studies showed hydrogen bonding between the CC and the PLA matrix. The X-ray diffraction (XRD and differential scanning calorimetry (DSC studies showed that the percentage crystallinity of PLA in composites was found to be higher than that of neat PLA as a result of the nucleating ability of the crystalline cellulose. Furthermore, Vicker hardness and yield strength were found to increase with increasing cellulose content in the composite. The SEM images of the fracture surfaces of the composites were indicative of poor adhesion between the CC and the PLA matrix. The composite with 15% CC showed antibacterial effect though pure films but had no antimicrobial effect; on the other hand its cytotoxicity in biological medium was found to be medium which might be suitable for its potential biomedical applications.

  3. Cellulosic carbon fibers with branching carbon nanotubes for enhanced electrochemical activities for bioprocessing applications. (United States)

    Zhao, Xueyan; Lu, Xin; Tze, William Tai Yin; Kim, Jungbae; Wang, Ping


    Renewable biobased carbon fibers are promising materials for large-scale electrochemical applications including chemical processing, energy storage, and biofuel cells. Their performance is, however, often limited by low activity. Herein we report that branching carbon nanotubes can enhance the activity of carbonized cellulosic fibers, such that the oxidation potential of NAD(H) was reduced to 0.55 V from 0.9 V when applied for bioprocessing. Coordinating with enzyme catalysts, such hierarchical carbon materials effectively facilitated the biotransformation of glycerol, with the total turnover number of NAD(H) over 3500 within 5 h of reaction.

  4. Cotton-based Cellulose Nanomaterials for Applications in Composites and Electronics (United States)

    Farahbakhsh, Nasim

    A modern society demands development of highly valued and sustainable products via innovative process technologies and utilizing bio-based alternatives for petroleum based materials. Systematic comparative study of nanocellulose particles as a biodegradable and renewable reinforcing agent can help to develop criteria for selecting an appropriate candidate to be incorporated in polymer nanocomposites. Of particular interest has been nanocellulosic materials including cellulose nanocrystal (CNC) and micro/nanofibrilated cellulose (MFC/NFC) which possess a hierarchical structure that permits an ordered structure with unique properties that has served as building blocks for the design of green and novel materials composites for applications in flexible electronics, medicine and composites. Key differences exist in nanocellulosic materials as a result the process by which the material is produced. This research demonstrates the applicability for the use of recycled cotton as promising sustainable material to be utilized as a substrate for electronic application and a reinforcing agent choice that can be produced without any intensive purification process and be applied to synthetic-based polymer nanocomposites in melt-processing. (Abstract shortened by ProQuest.).

  5. Bacterial cellulose-kaolin nanocomposites for application as biomedical wound healing materials (United States)

    Wanna, Dwi; Alam, Catharina; Toivola, Diana M.; Alam, Parvez


    This short communication provides preliminary experimental details on the structure-property relationships of novel biomedical kaolin-bacterial cellulose nanocomposites. Bacterial cellulose is an effective binding agent for kaolin particles forming reticulated structures at kaolin-cellulose interfaces and entanglements when the cellulose fraction is sufficiently high. The mechanical performance of these materials hence improves with an increased fraction of bacterial cellulose, though this also causes the rate of blood clotting to decrease. These composites have combined potential as both short-term (kaolin) and long-term (bacterial cellulose) wound healing materials.

  6. Développement d’une application orientée événement pour les réseaux de capteurs sous Contiki


    LOUH, Amina Warda; LAROUCI, Bouchra


    Les réseaux de capteurs sans fil se caractérisent par l‟aspect miniaturisé et les ressources limitées en termes d‟énergie, calcul et stockage. Ils sont conçus pour plusieurs domaines d‟applications. Dans le cadre de notre projet, on a développé une application orientée événement pour les réseaux de capteurs sans fil sous Contiki. Cette application consiste à envoyer une alerte quand un événement pertinent survient. Pour réaliser cette application, nous avons utilisé des outils logiciels...

  7. Guides d'ondes infrarouges pour applications en télécommunications, capteurs chimiques et biochimiques (United States)

    Smektala, F.; Bureau, B.; Adam, J. L.; Lucas, J.


    Les énergies de phonons élevés des verres à base de silice limitent leurs applications dans l'infrarouge. Il devient donc incontournable de créer des verres à plus faible énergie de phonons pour développer une optique passive guidée opérationnelle dans l'IR moyen et pour réaliser de nouveaux guide d'ondes optiques activés par des lanthanides pouvant jouer le rôle soit d'amplificateurs optiques soit de fibres lasers. Les compositions de verres stables répondant à ces critères sont exceptionnelles et appartiennent aux familles chimiques des fluorures et des chalcogénures. Les verres de fluorures, convenablement dopés par des terres rares, ont permis la réalisation d'amplificateurs optiques opérant dans la fenêtre télecom de la silice (1.3 μm avec le praséodyme, 1.45 μm avec le thulium et 1.55 μm avec l'erbium. Les verres de chalcogénures permettent la réalisation de fibres opérationnelles jusqu'à 12 μm mais seulement pour des applications courtes distances telles que le transport d'énergie moyenne, la radiométrie à l'ambiante et la spectrométrie IR déportée par fibre optique de molécules chimiques ou de tissus biologiques.

  8. Cellulose fibers extracted from rice and oat husks and their application in hydrogel. (United States)

    Oliveira, Jean Paulo de; Bruni, Graziella Pinheiro; Lima, Karina Oliveira; Halal, Shanise Lisie Mello El; Rosa, Gabriela Silveira da; Dias, Alvaro Renato Guerra; Zavareze, Elessandra da Rosa


    The commercial cellulose fibers and cellulose fibers extracted from rice and oat husks were analyzed by chemical composition, morphology, functional groups, crystallinity and thermal properties. The cellulose fibers from rice and oat husks were used to produce hydrogels with poly (vinyl alcohol). The fibers presented different structural, crystallinity, and thermal properties, depending on the cellulose source. The hydrogel from rice cellulose fibers had a network structure with a similar agglomeration sponge, with more homogeneous pores compared to the hydrogel from oat cellulose fibers. The hydrogels prepared from the cellulose extracted from rice and oat husks showed water absorption capacity of 141.6-392.1% and high opacity. The highest water absorption capacity and maximum stress the compression were presented by rice cellulose hydrogel at 25°C. These results show that the use of agro-industrial residues is promising for the biomaterial field, especially in the preparation of hydrogels.

  9. New cellulose-lignin hydrogels and their application in controlled release of polyphenols

    Energy Technology Data Exchange (ETDEWEB)

    Ciolacu, Diana, E-mail:; Oprea, Ana Maria; Anghel, Narcis; Cazacu, Georgeta; Cazacu, Maria


    Novel superabsorbant cellulose-lignin hydrogels (CL) were prepared by a new two-step procedure consisting in dissolving cellulose in an alkaline solution with further mixing with lignin, followed by the chemical crosslinking with epichlorohydrin. The crosslinking occurrence was verified by Fourier Transform Infrared spectroscopy (FT-IR). The effect of the structure features of cellulose-lignin hydrogels on their dehydration heat was evaluated by Differential Scanning Calorimetry (DSC). The Scanning Electron Microscopy (SEM) images reveal some morphological aspects of the hydrogels. The degree as well as the rate of swelling in a mixture of water:ethanol = 19:1 were estimated. The possible application of these hydrogels as controlled release systems was tested. Polyphenols known as having a wide range of biological effects were selected to be incorporated in such hydrogels by an optimal procedure. The extract of grapes seeds from the Chambourcin type was used as a source of polyphenols (PF). The amount of the incorporated polyphenols was estimated by UV-VIS measurements. Characterization of the hydrogels containing polyphenols was performed by FTIR spectroscopy. Some parameters were estimated based on the registered spectra, as H-bond energy (E{sub H}), the asymmetric index (a/b) and the enthalpy of H-bond formation ({Delta}H). The modifications of the thermal behavior and morphology induced by the presence of the polyphenols in hydrogels were highlighted by DSC and SEM, respectively. The release of polyphenols from CL hydrogels depended on the lignin content from matrices, as assessed by spectral studies. Both loading with polyphenols and their release can be controlled by the composition of the hydrogels. The kinetic of polyphenols release was studied. - Highlights: Black-Right-Pointing-Pointer A unique method to obtain cellulose-lignin hydrogels. Black-Right-Pointing-Pointer The application of these hydrogels as controlled release systems was tested. Black

  10. Isoniazid loaded gelatin-cellulose whiskers nanoparticles for controlled drug delivery applications

    Indian Academy of Sciences (India)



    Natural polymers like gelatin have been used as a potential drug carrier for controlled delivery applications due to their various advantages over synthetic polymers. Cellulose Whiskers (CWs) have the capacity to form strong hydrogen bonds which help in controlling the release of drug and also provide goodstrength to the drug carrier. In this report, CWs were prepared from filter paper cellulose by acid hydrolysis. Also, attempt was made to prepare gelatin-CWs nanoparticles by desolvation method using an anti-tuberculosis drug, isoniazid and a crosslinker glutaraldehyde (GA). The CWs and gelatin-CWs nanoparticles were characterized by X-ray diffractometry (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The effect of CWs on gelatin nanoparticlesover 8-hour period was measured in swelling studies. Efficiency of drug loading and subsequent release of isoniazid in buffer solutions at pH 1.2 (0.1N HCl) and pH 7.4 (phosphate buffer) were studied. Cytotoxicity study showed less toxicity for gelatin-CWs nanoparticles.

  11. Carboxymethyl Cellulose Acetate Butyrate: A Review of the Preparations, Properties, and Applications

    Directory of Open Access Journals (Sweden)

    Mohamed El-Sakhawy


    Full Text Available Carboxymethyl cellulose acetate butyrate (CMCAB has gained increasing importance in several fields, particularly in coating technologies and pharmaceutical research. CMCAB is synthesized by esterification of CMC sodium salt with acetic and butyric anhydrides. CMCAB mixed esters are relatively high molecular weight (MW thermoplastic polymers with high glass transition temperatures (Tg. CMCAB ester is dispersible in water and soluble in a wide range of organic solvents, allowing varied opportunity to the solvent choice. It makes application of coatings more consistent and defect-free. Its ability to slow down the release rate of highly water-soluble compounds and to increase the dissolution of poorly soluble compounds makes CMCAB a unique and potentially valuable tool in pharmaceutical and amorphous solid dispersions (ASD formulations.

  12. Microcrystalline cellulose: Isolation, characterization and bio-composites application-A review. (United States)

    Trache, Djalal; Hussin, M Hazwan; Hui Chuin, Caryn Tan; Sabar, Sumiyyah; Fazita, M R Nurul; Taiwo, Owolabi F A; Hassan, T M; Haafiz, M K Mohamad


    Considering its widespread usage in various fields, such as food, pharmaceutical, medical, cosmetic and polymer composites industries, microcrystalline cellulose (MCC) is becoming impellent due to increasing demand of alternatives to non-renewable and scarce fossil materials. Although it still suffers from some drawbacks, MCC has recently gained more interest owing to its renewability, non-toxicity, economic value, biodegradability, high mechanical properties, high surface area and biocompatibility. New sources, new isolation processes, and new treatments are currently under development to satisfy the increasing demand of producing new types of MCC-based materials on an industrial scale. Therefore, this review assembles the current knowledge on the isolation of MCC from different sources using various procedures, its characterization, and its application in bio-composites. Challenges and future opportunities of MCC-based composites are discussed as well as obstacles remaining for their extensive uses.

  13. Synthesis of polymer electrolyte membranes from cellulose acetate/poly(ethylene oxide)/LiClO{sub 4} for lithium ion battery application

    Energy Technology Data Exchange (ETDEWEB)

    Nurhadini,, E-mail:; Arcana, I Made, E-mail: [Inorganic and Physical Chemistry Research Division, Faculty of Mathematics and Natural Sciences, Institiut Teknologi Bandung, Jalan Ganesha 10, Bandung 40132 (Indonesia)


    This study was conducted to determine the effect of cellulose acetate on poly(ethylene oxide)-LiClO{sub 4} membranes as the polymer electrolyte. Cellulose acetate is used as an additive to increase ionic conductivity and mechanical property of polymer electrolyte membranes. The increase the percentage of cellulose acetate in membranes do not directly effect on the ionic conductivity, and the highest ionic conductivity of membranes about 5,7 × 10{sup −4} S/cm was observed in SA/PEO/LiClO{sub 4} membrane with cellulose ratio of 10-25% (w/w). Cellulose acetate in membranes increases mechanical strength of polymer electrolyte membranes. Based on TGA analysis, this polymer electrolyte thermally is stable until 270 °C. The polymer electrolyte membrane prepared by blending the cellulose acetate, poly(ethylene oxide), and lithium chlorate could be potentially used as a polymer electrolyte for lithium ion battery application.

  14. Graphene-oxide stabilization in electrolyte solutions using hydroxyethyl cellulose for drug delivery application. (United States)

    Mianehrow, Hanieh; Moghadam, Mohamad Hasan Mohamadzadeh; Sharif, Farhad; Mazinani, Saeedeh


    Stabilization of graphene oxide (GO) in physiological solution is performed using hydroxyethyl cellulose (HEC) to make the resultant nanohybrid suitable for targeted drug delivery purposes. Short and long term stability of GO suspensions with different ionic strengths were assessed using ultraviolet-visible spectroscopy (UV-vis), atomic force microscopy (AFM) and zeta potential measurements. Results depicted that HEC effectively stabilized GO in electrolyte solutions and the mechanism of stabilization appeares to be depended on HEC content. Drug loading and release behavior of folic acid (FA) as a model drug, from GO-HEC nanohybrid were studied to assess its application in drug delivery systems. Results showed the nanohybrid could be highly loaded by folic acid. Moreover, HEC content in the nanohybrid played an important role in final application to make it applicable either as a carrier for controllable drug release or as a folate-targeted drug carrier. In addition, according to cytotoxicity results, the nanohybrid showed good biocompatibility which indeed confirms its potential application as a drug carrier.

  15. Cellulose binding domain proteins (United States)

    Shoseyov, Oded; Shpiegl, Itai; Goldstein, Marc; Doi, Roy


    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  16. Neural Networks and Their Applications for the Oil Industry Les réseaux neuronaux et leurs applications pour l'industrie pétrolière

    Directory of Open Access Journals (Sweden)

    Fogelman-Soulie F.


    Full Text Available Neural Networks can be used in many different areas of problems related to Petroleum Exploration and Production. There already exist well defined classes of applications, together with appropriate Neural Networks architectures. Detailed theoretical results allow to monitor and evaluate the results obtained by Neural Networks. Sophisticated applications will certainly require the use of multi-modular architectures. Les réseaux neuronaux peuvent être utilisés pour de nombreux problèmes dans les domaines de l'exploration et la production de pétrole. Il existe d'ores et déjà des classes d'applications bien définies, pour lesquelles on connaît les architectures neuronales les plus adaptées. Des résultats théoriques précis permettent de contrôler et d'évaluer les performances obtenues avec les réseaux neuronaux. Les applications complexes demanderont certainement la mise en oeuvre d'architectures multi-modulaires.

  17. Cellulose nanocrystals in nanocomposite approach: Green and high-performance materials for industrial, biomedical and agricultural applications (United States)

    Fortunati, E.; Torre, L.


    The need to both avoid wastes and find new renewable resources has led to a new and promising research based on the possibility to revalorize the biomass producing sustainable chemicals and/or materials which may play a major role in replacing systems traditionally obtained from non-renewable sources. Most of the low-value biomass is termed lignocellulosic, referring to its main constituent biopolymers: cellulose, hemicelluloses and lignin. In this context, nanocellulose, and in particular cellulose nanocrystals (CNC), have gain considerable attention as nanoreinforcement for polymer matrices, mainly biodegradable. Derived from the most abundant polymeric resource in nature and with inherent biodegradability, nanocellulose is an interesting nanofiller for the development of nanocomposites for industrial, biomedical and agricultural applications. Due to the high amount of hydroxyl groups on their surface, cellulose nanocrystals are easy to functionalize. Well dispersed CNC are able, in fact, to enhance several properties of polymers, i.e.: thermal, mechanical, barrier, surface wettability, controlled of active compound and/or drug release. The main objective here is to give a general overview of CNC applications, summarizing our recent developments of bio-based nanocomposite formulations reinforced with cellulose nanocrystals extracted from different natural sources and/or wastes for food packaging, medical and agricultural sectors.

  18. Research and Application of Bacterial Cellulose%细菌纤维素的研究及其应用

    Institute of Scientific and Technical Information of China (English)

    贾士儒; 刘淼; 薄涛


    As a novel nanomaterial ,bacterial cellulose ( BC ) has attracted more attention due to its high quality in mechanical strength ,biocompatibility and biodegradability .This paper introduces the domestic and international researches on the metabolism and biosynthesis mechanism of bacterial cellulose . Meanwhile ,the applications of bacterial cellulose in food ,paper making and biomedical materials etc .were presented.Finally, the furture research trends and application prospects of bacterial cellulose were discussed .%细菌纤维素作为新型纳米材料,具有极好的物理特性、生物相容性和生物可降解性等。本文介绍了国内外目前对细菌纤维素代谢及生物合成机制的研究现状,及细菌纤维素在食品、造纸和医学等领域的应用。并展望了细菌纤维素未来的研究趋势与应用前景。

  19. Mucoadhesive cellulosic derivative sponges as drug delivery system for vaginal application. (United States)

    Furst, Tania; Piette, Marie; Lechanteur, Anna; Evrard, Brigitte; Piel, Géraldine


    Vaginal delivery of active drugs has been largely studied for local and systemic applications. It is well known that vagina is a complex route, due to physiological and non-physiological changes. Therefore, in order to achieve a prolonged local effect, these variations have to be considered. The aim of this study was to formulate and to characterize a solid system, called sponges, obtained by lyophilization of cellulosic derivative (HEC 250M) hydrogels. These sponges have to meet particular criteria to be adapted for vaginal application: they have to adhere to the vaginal cavity and to be rehydrated by the small amount of vaginal fluids. Moreover, they have to be easily manipulated and to be stable. Three freezing temperatures have been tested to prepare sponges (-15°C, -25°C, -35°C). By SEM analyzes, it was observed that the pores into the sponges were smaller and numerous as the freezing temperature decreases. However, this temperature did not have any influence on the rehydration speed that was rather influenced by the HEC concentration. Viscosity and mucoadhesive strength of hydrogels and corresponding sponges were also measured. It appeared that these parameters are mainly dependent on the HEC concentration. These mucoadhesive sponges can be considered as potential drug delivery systems intended for vaginal application.

  20. Exploring biosensor applications with cotton cellulose nanocrystalline protein and peptide conjugates (United States)

    Sensor I: Nano-crystalline preparations were produced through acid hydrolysis and mechanical breakage of the cotton fibers from a scoured and bleached cotton fabric and a scoured and bleached, mercerized fabric, which was shown to produce cellulose I (NCI) and cellulose II (NCII) crystals respective...

  1. A versatile pathway to end-functionalized cellulose ethers for click chemistry applications. (United States)

    Kamitakahara, Hiroshi; Suhara, Ryo; Yamagami, Mao; Kawano, Haruko; Okanishi, Ryoko; Asahi, Tomoyuki; Takano, Toshiyuki


    This paper describes a versatile pathway to heterobifunctional/telechelic cellulose ethers, such as tri-O-methyl cellulosyl azide and propargyl tri-O-methyl celluloside, having one free C-4 hydroxyl group attached to the glucosyl residue at the non-reducing end for the use in Huisgen 1,3-dipolar cycloaddition and copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The one-step end-functionalization of cellulose ethers for molecular rod synthesis involves the introduction of two reactive groups at both ends of the cellulose molecule, and can afford linear triblock copolymers via CuAAC and further reactions. We were able to tailor the degree of polymerization of end-functionalized cellulose ethers with controlled amounts of a Lewis acid, namely SnCl4. Chemical structures of the above cellulose ethers and the reaction conditions for controlling molecular length are discussed.

  2. Carboxymethyl cellulose enables silk fibroin nanofibrous scaffold with enhanced biomimetic potential for bone tissue engineering application. (United States)

    Singh, B N; Panda, N N; Mund, R; Pramanik, K


    Novel silk fibroin (SF) and carboxymethyl cellulose (CMC) composite nanofibrous scaffold (SFC) were developed to investigate their ability to nucleate bioactive nanosized calcium phosphate (Ca/P) by biomineralization for bone tissue engineering application. The composite nanofibrous scaffold was prepared by free liquid surface electrospinning method. The developed composite nanofibrous scaffold was observed to control the size of Ca/P particle (≤100nm) as well as uniform nucleation of Ca/P over the surface. The obtained nanofibrous scaffolds were fully characterized for their functional, structural and mechanical property. The XRD and EDX analysis depicted the development of apatite like crystals over SFC scaffolds of nanospherical in morphology and distributed uniformly throughout the surface of scaffold. Additionally, hydrophilicity as a measure of contact angle and water uptake capacity is higher than pure SF scaffold representing the superior cell supporting property of the SF/CMC scaffold. The effect of biomimetic Ca/P on osteogenic differentiation of umbilical cord blood derived human mesenchymal stem cells (hMSCs) studied in early and late stage of differentiation shows the improved osteoblastic differentiation capability as compared to pure silk fibroin. The obtained result confirms the positive correlation of alkaline phosphatase activity, alizarin staining and expression of runt-related transcription factor 2, osteocalcin and type1 collagen representing the biomimetic property of the scaffolds. Thus, the developed composite has been demonstrated to be a potential scaffold for bone tissue engineering application.


    Directory of Open Access Journals (Sweden)

    Viviane da Costa Correia


    Full Text Available Organosolv pulping is the clean chemical process of using organic solvents to aid in the removal of lignin and hemicellulose from lignocellulosic raw materials. This method provides facility for solvent recovery at the end of the process. In this work, it was to produce bamboo cellulosic pulp by the organosolv process evaluating different temperatures and reaction times, and the pulps were analyzed aiming their future application in the reinforcement of composites. The production of bamboo pulp by the organosolv process was studied varying the cooking conditions at 1, 2 and 3 h and 150, 170 and 190oC of temperature, in order to achieve the ideal conditions of yield, chemical and morphological characteristics of the pulp for its potential application in the reinforcement of composites. The best results for delignification (kappa number of 38, with relatively lower fiber degradation (viscosity of 625 cm3 g-1, aspect ratio of 40.4 and the index zero-span of 204 Nm g-1, were achieved for the pulping process at 190oC for 2 h. These pulping conditions can be considered as the more appropriate in the range of time intervals evaluated in this work. The higher mechanical strength and the lower incidence of morphological defects in the fiber (6.0% of curls and 10.6% of kinks can demonstrate the potential of organosolv bamboo pulp as a reinforcing element.

  4. Photonic Metamaterials for Defence and Security Applications (Les meta-materiaux photoniques pour les applications de defense et de securite) (United States)


    exceptionnelles qui ne sont pas facilement observables dans les matériaux naturels . La plupart des recherches sur les méta-matériaux ont été consacrées à...matériaux naturels ) est une des principales raisons qui a poussé les chercheurs à approfondir leurs études sur les méta-matériaux. Avec un index...rapports signal/bruit plus importants, une vitesse plus élevée, une taille réduite, et une gamme plus large pour les systèmes de capteurs optiques

  5. Development of Injectable Hyaluronic Acid/Cellulose Nanocrystals Bionanocomposite Hydrogels for Tissue Engineering Applications. (United States)

    Domingues, Rui M A; Silva, Marta; Gershovich, Pavel; Betta, Sefano; Babo, Pedro; Caridade, Sofia G; Mano, João F; Motta, Antonella; Reis, Rui L; Gomes, Manuela E


    Injectable hyaluronic acid (HA)-based hydrogels compose a promising class of materials for tissue engineering and regenerative medicine applications. However, their limited mechanical properties restrict the potential range of application. In this study, cellulose nanocrystals (CNCs) were employed as nanofillers in a fully biobased strategy for the production of reinforced HA nanocomposite hydrogels. Herein we report the development of a new class of injectable hydrogels composed of adipic acid dihydrazide-modified HA (ADH-HA) and aldehyde-modified HA (a-HA) reinforced with varying contents of aldehyde-modified CNCs (a-CNCs). The obtained hydrogels were characterized in terms of internal morphology, mechanical properties, swelling, and degradation behavior in the presence of hyaluronidase. Our findings suggest that the incorporation of a-CNCs in the hydrogel resulted in a more organized and compact network structure and led to stiffer hydrogels (maximum storage modulus, E', of 152.4 kPa for 0.25 wt % a-CNCs content) with improvements of E' up to 135% in comparison to unfilled hydrogels. In general, increased amounts of a-CNCs led to lower equilibrium swelling ratios and higher resistance to degradation. The biological performance of the developed nanocomposites was assessed toward human adipose derived stem cells (hASCs). HA-CNCs nanocomposite hydrogels exhibited preferential cell supportive properties in in vitro culture conditions due to higher structural integrity and potential interaction of microenvironmental cues with CNC's sulfate groups. hASCs encapsulated in HA-CNCs hydrogels demonstrated the ability to spread within the volume of gels and exhibited pronounced proliferative activity. Together, these results demonstrate that the proposed strategy is a valuable toolbox for fine-tuning the structural, biomechanical, and biochemical properties of injectable HA hydrogels, expanding their potential range of application in the biomedical field.

  6. The association effect of quaternary ammonium salt on carboxymethyl cellulose and its analytical applications. (United States)

    Wang, Yanhua; Gao, Chanjuan; Yang, Shengke


    Sodium carboxymethyl cellulose (CMC) has been extensively used in petroleum, geology, common household chemicals, food, medicine and other industries, owing to its excellent water-soluble, emulsifying, water retention and film forming properties. It is known as 'industrial monosodium glutamate'. However, the research of the test method on CMC is far behind the research of its actual application value. This study showed that, weak acid or weak basic medium, the carboxyl groups dissociated from CMC, existing as a big negative ion, which can form ion-association complexes with some quaternary ammonium cations through electrostatic and hydrophobic interactions. The absorption spectrum changes and Triton-X100 can increase the sensitivity of the system. The maximum absorption wavelengths are, respectively, about 256 nm for dodecyl trimethyl ammonium bromide (LTAB), 244 nm for tetradecyltrimethyl ammonium bromide (TTAB) and 240 nm for cetyltrimethyl ammonium bromide (CTAB) with CMC. The reactions show very high sensitivities and the maximum molar absorption coefficients are 1.10 × 10(4) L/(mol·cm) for LTAB system, 1.24 × 10(6) L/(mol·cm) for TTAB system and 1.78 × 10(6) L/(mol·cm) for CTAB system. This method is simple and rapid, and can be applied for the spectrophotometric determination of trace CMC in the supernatant of centrifuged drilling mud.

  7. Architecture Logicielles pour des Applications h\\'et\\'erog\\`enes, distribu\\'ees et reconfigurables

    CERN Document Server

    Louberry, Christine; Roose, Philippe


    The recent apparition of mobile wireless sensor aware to their physical environment and able to process information must allow proposing applications able to take into account their physical context and to react according to the changes of the environment. It suppose to design applications integrating both software and hardware components able to communicate. Applications must use context information from components to measure the quality of the proposed services in order to adapt them in real time. This work is interested in the integration of sensors in distributed applications. It present a service oriented software architecture allowing to manage and to reconfigure applications in heterogeneous environment where entities of different nature collaborate: software components and wireless sensors.


    Directory of Open Access Journals (Sweden)

    Raquel Janissek-Muniz


    Full Text Available Cet article propose un usage innovant de la méthode L.E.SCAnning® pour le suivi de l’environnent. Avec une étude de cas, conduite dans une entreprise brésilienne, ayant comme domaine d’application l'évaluation des actions disponibles sur le marché, nous avons cherché à interpréter de futurs scénarios. La méthodologie est basée sur la recherche qualitative exploratoire, en utilisant des informations collectées. Les informations ont été organisées par cible puis regroupées par affinité (Méthode Puzzle. Ce travail cherche à démontrer que, en appliquant la méthode sur le marché d'actions, il est possible de produire des connaissances actionnables, et de construire, voire anticiper, des représentations futures

  9. Titanium dioxide-cellulose hybrid nanocomposite and its glucose biosensor application

    Energy Technology Data Exchange (ETDEWEB)

    Maniruzzaman, Mohammad; Jang, Sang-Dong [Center for EAPap Actuator, Department of Mechanical Engineering, INHA University, Incheon 402-751 (Korea, Republic of); Kim, Jaehwan, E-mail: [Center for EAPap Actuator, Department of Mechanical Engineering, INHA University, Incheon 402-751 (Korea, Republic of)


    Highlights: Black-Right-Pointing-Pointer An organic-inorganic hybrid nanocomposite was fabricated by blending TiO{sub 2} nanoparticles and cellulose solution. Black-Right-Pointing-Pointer The hybrid nanocomposite has advantages of biodegradability and bio-compatibility of cellulose and physical properties of TiO{sub 2}. Black-Right-Pointing-Pointer Enzyme glucose oxidase (GOx) was immobilized into the hybrid nanocomposite and covalent bonding between TiO{sub 2} and GOx was confirmed by X-ray photoelectron analysis. Black-Right-Pointing-Pointer Linear response of the glucose biosensor was obtained in the range of 1-10 mM. - Abstract: This paper investigates the fabrication of titanium dioxide (TiO{sub 2})-cellulose hybrid nanocomposite and its possibility for a conductometric glucose biosensor. TiO{sub 2} nanoparticles were blended with cellulose solution prepared by dissolving cotton pulp with lithium chloride/N,N-dimethylacetamide solvent to fabricate TiO{sub 2}-cellulose hybrid nanocomposite. The enzyme, glucose oxidase (GOx) was immobilized into this hybrid nanocomposite by physical adsorption method. The successful immobilization of glucose oxidase into TiO{sub 2}-cellulose hybrid nanocomposite via covalent bonding between TiO{sub 2} and GOx was confirmed by X-ray photoelectron analysis. The linear response of the glucose biosensor is obtained in the range of 1-10 mM. This study demonstrates that TiO{sub 2}-cellulose hybrid nanocomposite can be a potential candidate for an inexpensive, flexible and disposable glucose biosensor.

  10. 纤维素Schiff碱的性质及应用%The properties and applications of Schiff’s bases of cellulose

    Institute of Scientific and Technical Information of China (English)



    纤维素Schiff碱是一种环保的纤维素衍生物,在很多行业具有很大的发展潜力。文章简述了纤维素Schiff碱结构、性质及应用。%Schiff’s base of cellulose is a kind of cellulose derivatives .It will be had great potentialities in any industry. In this paper, the constitution, properties and applications of Schiff’s bases of cellulose were mainly introduced.


    Institute of Scientific and Technical Information of China (English)

    Yun Chen; Xiao-peng Xiong; Guang Yang; Li-na Zhang; Sen-lin Lei; Hui Lianga


    A series of cellulose acetate membranes were prepared by using formamide as additive, and then were hydrolyzedin 4 wt% aqueous NaOH solution for 8 h to obtain regenerated cellulose membranes. The dependence of degree ofsubstitution, structure, porous properties, solubility and thermal stability on hydrolysis time was studied by chemical titration,Fourier transform infrared spectroscopy, scanning electron microscopy, wide-angle X-ray diffraction, and differentialscanning calorimetry, respectively. The results indicated that the pore size of the regenerated cellulose membranes wasslightly smaller than that of cellulose acetate membrane, while solvent-resistance, crystallinity and thermostability weresignificantly improved. This work provides a simple way to prepare the porous cellulose membranes, which not only kept thegood pore characteristics of cellulose acetate membranes, but also possessed solvent-resistance, high crystallinity andthermostability. Therefore, the application range of cellulose acetate membranes can be expanded.

  12. Application pour payer dans les cafétérias des sites CERN de Meyrin

    CERN Multimedia


    A compter du 18 octobre 2016, Novae met en place dans tous ses points de restauration du site de Meyrin (restaurants 1, 2 et cafétérias) un système de paiement via l’application en ligne Mobino. Mode d’emploi pas à pas: infographie animée de 30 secondes.

  13. Characterization of TEMPO-oxidized bacterial cellulose scaffolds for tissue engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Honglin [School of Materials Science and Engineering, Tianjin University, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Xiong, Guangyao [School of Mechanical and Electrical Engineering, East China Jiaotong University, Nanchang, Jiangxi 330013 (China); Hu, Da [School of Materials Science and Engineering, Tianjin University, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Ren, Kaijing [Department of Joint Surgery, Tianjin Hospital, Tianjin 300211 (China); Yao, Fanglian; Zhu, Yong [School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Gao, Chuan [School of Materials Science and Engineering, Tianjin University, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Wan, Yizao, E-mail: [School of Materials Science and Engineering, Tianjin University, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China)


    Introduction of active groups on the surface of bacterial cellulose (BC) nanofibers is one of the promising routes of tailoring the performance of BC scaffolds for tissue engineering. This paper reported the introduction of aldehyde groups to BC nanofibers by 2,2,6,6-tetramethylpyperidine-1-oxy radical (TEMPO)-mediated oxidation and evaluation of the potential of the TEMPO-oxidized BC as tissue engineering scaffolds. Periodate oxidation was also conducted for comparison. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses were carried out to determine the existence of aldehyde groups on BC nanofibers and the crystallinity. In addition, properties relevant to scaffold applications such as morphology, fiber diameter, mechanical properties, and in vitro degradation were characterized. The results indicated that periodate oxidation could introduce free aldehyde to BC nanofibers and the free aldehyde groups on the TEMPO-oxidized BC tended to transfer to acetal groups. It was also found that the advantageous 3D structure of BC scaffolds remained unchanged and that no significant changes in morphology, fiber diameter, tensile structure and in vitro degradation were found after TEMPO-mediated oxidation while significant differences were observed upon periodate oxidation. The present study revealed that TEMPO-oxidation could impart BC scaffolds with new functions while did not degrade their intrinsic advantages. - Highlights: • TEMPO-mediated oxidation on BC scaffold for tissue engineering use was conducted. • TEMPO-mediated oxidation did not degrade the intrinsic advantages of BC scaffold. • TEMPO-mediated oxidation could impart BC scaffold with new functional groups. • Feasibility of TEMPO-oxidized BC as tissue engineering scaffold was confirmed.

  14. Synthèse par voie hydrothermale des orthophosphates de lanthanides pour des applications optiques


    Garrido-Hernandez, Aristeo


    Rare earth (Re) doped lanthanide orthophosphates (LnPO4) are considered like promising phosphors for optical applications. Phosphors are luminescent materials which convert certain types of energy (X-ray, ultraviolet, visible, infrared) mainly into visible light. In this research Eu3+ (europium), Ce3+ (cerium), Tb3+ (terbium), Er3+ (erbium), Tm3+ (thulium) and/or Yb3+ (ytterbium) doped LuPO4 (lutetium orthophosphate), YPO4 (yttrium orthophosphate), GdPO4 (gadolinium orthophosphate) and/or Gdx...

  15. Aerogel microspheres from natural cellulose nanofibrils and their application as cell culture scaffold. (United States)

    Cai, Hongli; Sharma, Sudhir; Liu, Wenying; Mu, Wei; Liu, Wei; Zhang, Xiaodan; Deng, Yulin


    We demonstrated that ultralight pure natural aerogel microspheres can be fabricated using cellulose nanofibrials (CNF) directly. Experimentally, the CNF aqueous gel droplets, produced by spraying and atomizing through a steel nozzle, were collected into liquid nitrogen for instant freezing followed by freeze-drying. The aerogel microspheres are highly porous with bulk density as low as 0.0018 g cm(-3). The pore size of the cellulose aeogel microspheres ranges from nano- to macrometers. The unique ultralight and high porous structure ensured high moisture (~90 g g(-1)) and water uptake capacity (~100 g g(-1)) of the aerogel microspheres. Covalent cross-linking between the native nanofibrils and cross-linkers made the aerogel microspheres very stable even in a harsh environment. The present study also confirmed this kind of aerogel microspheres from native cellulose fibers can be used as cell culture scaffold.


    Directory of Open Access Journals (Sweden)

    Jing Shen,


    Full Text Available The application of fillers at the surface of cellulosic paper is an interesting and industrially-commercialized but not very well-known concept, in which the filler particles are essentially added to the voids of the fibrous matrixes. This so-called “surface filling” can be achieved by the use of fillers together with a polymer solution via film press or size press, an approach that is distinct from both wet-end filling and conventional coating of paper. As an easily practicable process, surface filling has some advantages over direct wet-end addition of fillers, such as minimizing the adverse effects of filler addition on paper strength. Efficient surface filling is somewhat dependent on the specific characteristics of both fillers and fibrous matrixes. Surface filling may provide interesting possibilities for the papermaking discipline; for example, it would open the door to maximizing the cost-effectiveness of paper mills, and efficiently adding new functionalities to cellulosic paper. From both practical and fundamental points of view, systematic exploration and understanding of surface filling of cellulosic paper would be of great significance to the papermaking industry.

  17. Preparation of 14C Radiolabelled Sodium Carboxymethyl Cellulose

    Institute of Scientific and Technical Information of China (English)

    CHEN; Bao-jun; YANG; Hong-wei; LI; Shuai


    Carboxymethyl cellulose(CMC)is a kind of cellulose derivative.CMC has wide applications,including food,daily chemicals,pharmaceutical industry and chemical industry,etc.In order to study the metabolism of CMC,the sodium carboxymethyl cellulose was labelled with 14C.The carboxymethyl cellulose was labelled with 14C by treatment with alkalized cellulose and 14C-

  18. Amelioration de la precision d'un bras robotise pour une application d'ebavurage (United States)

    Mailhot, David

    Process automation is a more and more referred solution when it comes to complex, tedious or even dangerous tasks for human. Flexibility, low cost and compactness make industrial robots very attractive for automation. Even if many developments have been made to enhance robot's performances, they still can not meet some industries requirements. For instance, aerospace industry requires very tight tolerances on a large variety of parts, which is not what robots were designed for at first. When it comes to robotic deburring, robot imprecision is a major problem that needs to be addressed before it can be implemented in production. This master's thesis explores different calibration techniques for robot's dimensions that could overcome the problem and make the robotic deburring application possible. Some calibration techniques that are easy to implement in production environment are simulated and compared. A calibration technique for tool's dimensions is simulated and implemented to evaluate its potential. The most efficient technique will be used within the application. Finally, the production environment and requirements are explained. The remaining imprecision will be compensated by the use of a force/torque sensor integrated with the robot's controller and by the use of a camera. Many tests are made to define the best parameters to use to deburr a specific feature on a chosen part. Concluding tests are shown and demonstrate the potential use of robotic deburring. Keywords: robotic calibration, robotic arm, robotic precision, robotic deburring

  19. Damage - Permeability relation for concrete. Applications to structural computations; Relation endommagement permeabilite pour les betons

    Energy Technology Data Exchange (ETDEWEB)

    Jason, L


    The relation between damage and permeability is of great importance to evaluate the consequences of a mechanical loading on the hydraulic integrity of sensitive concrete structures like containment buildings of nuclear power plants. An elastic plastic damage constitutive law for the mechanical behaviour is first developed. The model is validated on elementary and structural applications with a special focus on the efficiency of the numerical tools (tangent matrices). A relation between water saturation (drying), damage and permeability is then proposed, based on theoretical and experimental observations. Finally, a Representative Structural Volume of a containment vessel is studied to highlight the influence of hygro - mechanical loading on the hydraulic behaviour (distribution of gas pressure). (author)


    A green approach is described that generates bulk quantities of nanocomposites containing transition metals such as Cu, Ag, In and Fe at room temperature using a biodegradable polymer carboxymethyl cellulose (CMC) by reacting respective metal salts with sodium salt of CMC in aqu...

  1. Preparation and Application as the Filler for Elastomers of Flake-Shaped Cellulose Particles and Nanofibers (United States)

    Nagatani, Asahiro; Lee, Seung-Hwan; Endo, Takashi; Tanaka, Tatsuya

    Fibrous cellulose made from wood pulp was mechanically milled into flake-shaped cellulose particles(FS-CPs) using a planetary ball mill with additives under several conditions. The average particle diameter of the FS-CPs was ca. 15μm, and the particles were available in a variety of thicknesses by changing the kind of the additives used in the milling process. FS-CPs-reinforced olefinic thermoplastic elastomer composites were prepared under melt mixing and passed through an open roll to orient the particles. The tensile modulus of the composites with a compatibilizer increased with increasing the particle content. The damping properties of the composites improved, compared to the neat elastomer. On the other hand, the fibrous cellulose was suspended in water, followed by wet disk-milled to prepare cellulose nanofibers(CNFs). The wet ground products showed nanoscopic fine morphology. CNFs-reinforced natural rubber(NR) composites were prepared by mixing the water suspension of CNFs with NR latex using a homogenizer. Then, it was dried in an oven and mixed again with vulcanizing ingredients of rubber using an open roll. The tensile properties of the composites improved remarkably by the addition of small amount of CNFs.

  2. Preparation and Application of Cationic Modified Cellulose Fibrils as a Papermaking Additive

    Directory of Open Access Journals (Sweden)

    Yanhong Gao


    Full Text Available This paper deals with cationic modified cellulose fibrils obtained by reacting the cellulose fibrils with 2,3-epoxypropyltrimethylammonium chloride (EPTMAC. The physical and chemical properties of unmodified cellulose fibrils (UMCF and cationic modified cellulose fibrils (CMCF were characterized by SEM, FTIR, degree of substitution, colloid titration, zeta potential, and thermogravimetric analysis. The experimental results showed that, after cationization, surface charge density and zeta potential reversed, thermal stability decreased, and new functional groups appeared, while the surface morphology did not show much difference from the UMCF. With the addition of three kinds of additives (UMCF, CMCF, and cationic starch (CS to BCTMP, the addition of UMCF and CMCF had little effect on zeta potential, while the addition of CS changed zeta potential obviously. With the increasing of additive amount, the bulk of paper sheets added CMCF did not change obviously, while the bulk of paper sheets added UMCF and CS decreased rapidly. With regard to physical strength, all the three kinds of additives could improve the tensile index and tear index; the tensile index of paper sheets added CS was higher than that of added UMCF and CMCF, while the tear index of paper sheets added CMCF was the highest among the three additives.

  3. 纤维素在锂离子电池隔膜中的应用%Application of cellulose in Li-ion battery separators

    Institute of Scientific and Technical Information of China (English)

    迟婷玉; 贺磊; 陈宗明; 吴立群


    概述了锂离子电池隔膜的研究现状,分析了纤维素在锂离子电池隔膜中应用的可行性,对三大类纤维素———天然纤维素、改性天然纤维素、再生纤维素及纤维素衍生物在锂离子电池隔膜中的应用进行了详细介绍,分析了其所在问题,并指明了未来的研究方向。%The research situation of Li_ion battery separators was overviewed in this paper.The possibility of the application of cellulose in Li_ion battery separators was presented.Application of cellulose,natural cellulose,modified cellulose,regenerated cellulose and cellulose derivatives in Li_ion battery separators was introduced in details,the problems in the current research work were analyzed and the development trends were discussed.

  4. Feasibility of e-paper made with cellulose (United States)

    Yoo, K. H.; Han, K. J.; Chen, Yi; Kang, K. S.; Kim, Jaehwan


    Cellulose is a beneficial material that has low cost, light weight, high compatibility, and biodegradability. Recently electro-active paper (EAPap) composed with cellulose was discovered as a smart material for application to variety industrial fields such as smart wall-paper, actuator, and magic carpet. It also exhibited actuator property through ion migration and piezoelectric effect. Since cellulose acetate (CA) film has optically transparent property, we focused on optical field application, such as electronic paper, prismsheet, and polarized film. Since CA can be easily dissolved in variety of organic solvent, various weight % (from 1 to 25 wt. %) of CA solution in acetone was prepared. Polydimethylsilane (PDMS) master pattern was fabricated on the silicone wafer. CA solution was poured to the master mold and dried using spin-coating or tape casting method. Various shape and height patterns, such as circle, honeycomb, and rectangular patterns were fabricated using 12 wt. % CA solution. The resulting pattern showed uniform size in the large area without defect. These patterns can be utilized as a substrate and cell pattern for the electronic paper. To investigate saponification (SA) effect to convert CA to regenerated cellulose, CA film was immersed into the sodium methoxide solution in methanol for various times. The fabricated CA films were stretched and immersed into the sodium methoxide solution in methanol to desubstitute the acetate group. These regenerated cellulose films have larger mechanical strength than CA films. Although the UV-visible transmittance was decreased as increasing SA time, the transmittance of the further SA process and stretched film backed up near untreated CA film. Although the cross-sectional image of the saponified and unstretched CA film did not have specific directional structure, the cross-sectional FESEM image of the saponified and stretched CA film had one directional fiber structure. The fiber was aligned to the stretched

  5. Impact of Biofield Treatment on Chemical and Thermal Properties of Cellulose and Cellulose Acetate


    Trivedi, Mahendra Kumar


    Cellulose being an excellent biopolymer has cemented its place firmly in many industries as a coating material, textile, composites, and biomaterial applications. In the present study, we have investigated the effect of biofield treatment on physicochemical properties of cellulose and cellulose acetate. The cellulose and cellulose acetate were exposed to biofield and further the chemical and thermal properties were investigated. X-ray diffraction study asserted that the biofield treatment did...

  6. Ionic Liquids and Cellulose: Dissolution, Chemical Modification and Preparation of New Cellulosic Materials

    Directory of Open Access Journals (Sweden)

    Mehmet Isik


    Full Text Available Due to its abundance and a wide range of beneficial physical and chemical properties, cellulose has become very popular in order to produce materials for various applications. This review summarizes the recent advances in the development of new cellulose materials and technologies using ionic liquids. Dissolution of cellulose in ionic liquids has been used to develop new processing technologies, cellulose functionalization methods and new cellulose materials including blends, composites, fibers and ion gels.

  7. Application of thin film cellulose composite membrane for dye wastewater reuse

    KAUST Repository

    Puspasari, Tiara


    The use of low cost membranes with high salt/dye selectivity and high flux is ideal for an economic and eco-friendly treatment of dye wastewater. Here, regenerated cellulose membranes prepared from trimethylsilyl cellulose are studied for treating artificial dye effluents. In the experiments using a feed containing Congo Red and high NaCl concentration, the membrane featured impressive dye removal with zero salt rejection combined with high flux. More interestingly, the membrane reached as much as 600 LMH flux at 80 °C and 4 bar while maintaining high dye rejection close to 98%. In prolonged experiments up to 75 h the membrane exhibited good antifouling behavior with nearly 100% flux recovery. This study may provide a promising alternative of dye effluent treatment where high amounts of monovalent salts are present. © 2016

  8. Application of ultra cellulose fiber for the enhancement of the durability


    Saaid I. Zaki


    Ultra Cellulose Fibers are hydrophilic fibers which can hold most of their weight water when it is mixed into concrete, after concrete is hardened, these fibers will slowly release this water to unhydrated cement during the critical early phases of curing which assist in more complete hydration, this internal self curing action results in more completely hydrated cement which contributes to more strength development and more control of internal microcracking, particularly when normal curin...

  9. The application of nanoindentation for determination of cellulose nanofibrils (CNF) nanomechanical properties (United States)

    Yildirim, N.; Shaler, S.


    Nanocellulose is a polymer which can be isolated from nature (woods, plants, bacteria, and from sea animals) through chemical or mechanical treatments, as cellulose nanofibrils (CNF), cellulose nanocrystals or bacterial celluloses. Focused global research activities have resulted in decreasing costs. A nascent industry of producers has created a huge market interest in CNF. However, there is still lack of knowledge on the nanomechanical properties of CNF, which create barriers for the scientist and producers to optimize and predict behavior of the final product. In this research, the behavior of CNF under nano compression loads were investigated through three different approaches, Oliver-Pharr (OP), fused silica (FS), and tip imaging (TI) via nanoindentation in an atomic force microscope. The CNF modulus estimates for the three approaches were 16.6 GPa, for OP, 15.8 GPa for FS, and 10.9 GPa for TI. The CNF reduced moduli estimates were consistently higher and followed the same estimate rankings by analysis technique (18.2, 17.4, and 11.9 GPa). This unique study minimizes the uncertainties related to the nanomechanical properties of CNFs and provides increased knowledge on understanding the role of CNFs as a reinforcing material in composites and also improvement in making accurate theoretical calculations and predictions.

  10. Cellulose Nanocrystals Obtained from Cynara Cardunculus and Their Application in the Paper Industry

    Directory of Open Access Journals (Sweden)

    Valentina Coccia


    Full Text Available Biorefinery aims at designing new virtuous and high-efficiency energy chains, achieving the combined production of biofuels (e.g., bioethanol and biobased products. This emerging philosophy can represent an important opportunity for the industrial world, exploiting a new kind of nano-smart biomaterials in their production chains. This paper will present the lab experience carried out by the Biomass Research Centre (CRB in extracting cellulose nanocrystals (NCC from a pretreated (via Steam Explosion fraction of Cynara cardunculus. This is a very common and invasive arboreal variety in central Italy. The NCC extraction methodology allows the separation of the crystalline content of cellulose. Such a procedure has been considered in the literature with the exception of one step in which the conditions have been optimized by CRB Lab. This procedure has been applied for the production of NCC from both Cynara cardunculus and microcrystalline cellulose (MCC. The paper will discuss some of the results achieved using the obtained nanocrystals as reinforcing filler in a paper sheet; it was found that the tensile strength increased from 3.69 kg/15 mm to 3.98 kg/15 mm, the durability behavior (measured by bending number changed from the value 95 to the value 141, and the barrier properties (measured by Gurley porosity were improved, increasing from 38 s to 45 s.

  11. 纤维素的改性及应用研究进展%Progress in modification of cellulose and application

    Institute of Scientific and Technical Information of China (English)

    罗成成; 王晖; 陈勇


    植物纤维素是天然的可再生资源,对纤维素的改性利用一直是研究的热点。本文简要介绍了纤维素的结构与性质,综述了纤维素的改性方法,包括物理改性、化学改性和生物改性等,其中化学改性是最主要的方法,包括酯化、磺化、醚化、醚酯化、交联和接枝共聚等,通常涉及其结构中羟基的一系列反应。通过改性,引进了一系列离子型基团,有利于增强纤维素的亲水性。经改性后的纤维素与之前相比,结晶度和聚合度明显降低,可及度明显提高,无论物理性质还是化学性质都表现出更大的优越性。其后回顾了纤维素衍生物在食品、造纸以及建筑行业中的一些研究应用成果,阐述了其在医药及废水处理等方面的研究进展,并展望了纤维素衍生物的发展前景。%Plant cellulose is a natural renewable resource,and application of the modified cellulose has been a research focus. The structure and properties of cellulose are described , and cellulose modification methods are reviewed,including physical,chemical and biological methods. The main method is chemical modification , including esterification , sulfonation , etherification , ether esterification,crosslinking and graft copolymerization,which involve the reactions of hydroxyl groups in the cellulose. Hydrophilcity of cellulose could be enhanced by introduction of ionic groups. Compared with non-modified cellulose , crystallinity and degree of polymerization of modified cellulose decrease significantly,whereas accessibility is improved remarkably,with superior physical and chemical properties. Finally,the research achievements of cellulose derivatives in food,paper and construction industries are reviewed. Research progresses in pharmaceuticals,wastewater treatment and other areas are presented. Future applications of cellulose derivatives are prospected.

  12. Transmission Sur Fibres Optiques Dans Un Systeme D'Archivage Et De Communication D'Images Pour Des Applications Medicales (United States)

    Aaron, Gilles; Bonnard, Rene


    Dans l'hOpital, le besoin d'un reseau de communication electronique ne cesse de crottre au fur et a mesure de la numerisation des images. Ce reseau local a pour but de relier quelques sources d'images telles la radiologie numerique, la tomodensitometrie, la resonance magnetique nucleaire, l'echographie ultraso-nore etc..., a un systme d'archivage. Des consoles de visualisation interacti-ves peuvent etre utilisees dans les salles d'examens, les bureaux des medecins et les services de soins. Dans un tel systme, trois caracteristiques princi-pales doivent etre prises en compte le debit, la longueur du cable et le nombre de connexions. - Le debit est tr?)s important, en effet, un temps de reponse maxima de quel-ques secondes doit etre garanti pour des images de plusieurs millions d'ele-ments binaires. - La distance entre connexions peut etre de quelques km dans certains grands hopitaux. - Le nombre de connexions au reseau ne depasse jamais quelques dizaines car les sources d'images et les unites de traitement representent des materiels importants, par ailleurs les consoles de visualisation simples peuvent etre groupees en grappe. Toutes ces conditions sont remplies par les transmissions sur fibres optiques. Selon la topologie et la methode d'accNs, deux solutions peuvent etre envisa-gees : - Anneau actif - Etoile active ou passive Enfin, les developpements de Thomson-CSF en composants pour transmissions optiques pour les grands reseaux de tel4distribution nous apportent un support technologique et une production de masse qui diminuera les collts du materiel.

  13. Cellulose binding domain fusion proteins (United States)

    Shoseyov, Oded; Shpiegl, Itai; Goldstein, Marc A.; Doi, Roy H.


    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  14. Fuel cells for stationary applications in Japan; Les piles a combustible pour les applications stationnaires au Japon

    Energy Technology Data Exchange (ETDEWEB)

    Hug, F.; Mermillod, N.; Millet, C.; Pinget, A.


    This document is a mission report on stationary applications of fuel cells in Japan. This mission was organized by the Science and Technology Service of the French embassy in Japan in December 1999. The organizations shown were: NEDO, Osaka Gas, Tokyo Gas, Sanyo, the Kawagoe facility, Mitsubishi Heavy Industries, CRIEPI and Toto. Since the year 2000, the public effort made on fuel cells development has shot up and reaches 7 billions of yen among which more than a half is devoted to polymer electrolyte fuel cells (PEFC). Applications of PEFCs are various, from stationary cogeneration to transportation systems. (J.S.)

  15. Réalisation d'un système de conversion et de gestion de l'énergie d'un système photovoltaïque pour l'alimentation des réseaux de capteurs sans fil autonome pour l'application aéronautique


    Meekhun, Dariga


    Le projet SACER vise à répondre aux demandes d’Airbus qui ont besoin de disposer de données décrivant le comportement d’un avion ou d’un satellite avant commercialisation ou lancement. Pour mieux répondre à cette demande, un réseau de capteurs sans fil remplacerait les équipements de test filaires existants. Le but est d’apporter des avantages tels qu’une réduction de poids, de coût et de connectique. Pour notre part, nous n’avons travaillé que sur l’application aéronautique.Pour alimenter le...

  16. Fabrication and characterization of novel biomimetic PLLA/cellulose/hydroxyapatite nanocomposite for bone repair applications

    Energy Technology Data Exchange (ETDEWEB)

    Eftekhari, Samin [Department of Chemical Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3 (Canada); El Sawi, Ihab; Bagheri, Zahra Shaghayegh [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3 (Canada); Turcotte, Ginette [Department of Chemical Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3 (Canada); Bougherara, Habiba, E-mail: [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3 (Canada)


    The purpose of this research is to develop and characterize a novel biomimetic nanocomposite that closely mimics the properties of real bone such as morphology, composition and mechanical characteristics. This novel porous nanocomposite is composed of cotton-sourced cellulose microcrystals, hydroxyapatite nanoparticles and poly L-lactide acid. A unique combination of commonly used fabrication procedures has been developed including pre-treatment of particles using a coupling agent. The effect of various weight ratios of the reinforcing agents was evaluated to assess their influence on the chemical, thermal, and mechanical properties of the nanocomposites. The prepared nanocomposites were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and compression testing. Our results indicated the presence of molecular interactions between all components leading to an increase of the crystallinity of the polymer from 50% to 80%. Compression test results revealed that increasing the weight ratio of microcrystalline cellulose/poly L-lactide acid and hydroxyapatite/poly L-lactide acid from 0.1 to 0.5 enhanced the compressive yield stress from 0.127 to 2.2 MPa and The Young's modulus from 6.6 to 38 MPa, respectively. It was found that the fabricated nanocomposites are comparable with the trabecular bone from compositional, structural, and mechanical point of view. - Highlights: • Fabrication of PLLA/HA/cellulose composites that mimic the spongeous bone • Homogenous dispersion of the reinforcing agents in the PLLA matrix was attained. • More efficient interface between the PLLA and the reinforcing agents was achieved. • Preliminary in vitro biocompatibility test showed the nontoxicity of the composite. • The crystallinity, the compressive strength and modulus were investigated.

  17. Investigation of Regenerated Cellulose/Poly(acrylic acid Composite Films for Potential Wound Healing Applications: A Preliminary Study

    Directory of Open Access Journals (Sweden)

    Manjula Bajpai


    Full Text Available Regenerated cellulose/poly(acrylic acid composite films have been synthesized for wound dressing applications. The water absorbency of these films was studied as a function of amount of cross-linker N,N′-methylenebisacrylamide and cellulose contents in the feed mixture. The samples, having different compositions, showed tensile strength and percent elongation in the range of 9.98×105 to 13.40×105 N/m2 and 110 to 265, respectively. The water vapor transmission rate (WVTR for various films was found to be in the range of 2.03 to 7.18 mg/cm2/h. These films were loaded with antibacterial drug miconazole nitrate and their release was studied in the physiological pH at 37°C. The release data was found to fit well the diffusion controlled Higuchi model. Finally the films demonstrated fair antibacterial and antifungal action, thus establishing their strong candidature as wound dressing materials.

  18. Membrane Made of Cellulose Acetate with Polyacrylic Acid Reinforced with Carbon Nanotubes and Its Applicability for Chromium Removal

    Directory of Open Access Journals (Sweden)

    J. A. Sánchez-Márquez


    Full Text Available Membranes made of carbon nanotubes and cellulose acetate with polyacrylic acid were designed in order to study their properties and their applicability for chromium removal. The membranes were prepared by phase inversion method using cellulose acetate and polyacrylic acid. Carbon nanotubes were added to the membrane during their process of synthesis in proportions of 1% by weight. The pores in the material are formed in layers, giving the effect of depth and forming a network. Both the carbon nanotubes and membranes were characterized by IR, Raman, and SEM spectroscopy. In addition, the concentration of acidic and basic sites and the surface charge in the materials were determined. The concentration of acid sites for oxidized nanotubes was 4.0 meq/g. The removal of Cr(VI was studied as a function of contact time and of initial concentration of Cr(VI. The removal of Cr(VI (~90% mainly occurs in a contact time from 32 to 64 h when the initial concentration of Cr(VI is 1 mg/L.

  19. Bioengineering cellulose-hemicellulose networks in plants

    NARCIS (Netherlands)

    Obembe, O.


    The interactions between cellulose and hemicellulose in the cell walls are important in the industrial application of the cellulose (natural) fibres. We strive to modify these interactions (i) by interfering with cellulose biosynthesis and (ii) by direct interference of the

  20. Adsorption and desorption of cellulose derivatives.

    NARCIS (Netherlands)

    Hoogendam, C.W.


    Cellulose derivatives, in particular carboxymethyl cellulose (CMC) are used in many (industrial) applications. The aim of this work is to obtain insight into the adsorption mechanism of cellulose derivatives on solid-liquid interfaces.In chapter 1 of this thesis we discuss some appl

  1. Etude de sécurité en base de données avec une application pour le contrôle d’accès


    EL HADJ MIMOUNE, Khadidja


    Dans le cadre de PFE, nous avons réalisé une application qui fait appel à des mécanismes de sécurité dans le cadre des bases de données. Notre application contient deux parties : la première est une application Web réalisée pour gérer les clients dans un environnement 3-tiers, nous avons proposé dans cette partie un contrôle d’accès sur le nombre de tentatives erronés d’authentification avant de désactiver un compte existant ainsi qu’un mécanisme de chiffrement afin de protéger les informatio...

  2. Développement d'une application orientée événement pour les réseaux de capteurs.




    L'objectif principal de ce mémoire est de développer une application de type Event-Driven pour les réseaux de capteurs sans fil dédiés aux applications critiques .Ce type d'application permet de minimiser l'énergie consommée par les capteurs et garantir par la suite une longue durée de vie à ces réseaux car il y aura transmission que s'il y a un événement pertinent qui survient et évite les transmissions périodiques qui sont couteuses en termes d'énergie.

  3. Pigment-cellulose nanofibril composite and its application as a separator-substrate in printed supercapacitors (United States)

    Torvinen, Katariina; Lehtimäki, Suvi; Keränen, Janne T.; Sievänen, Jenni; Vartiainen, Jari; Hellén, Erkki; Lupo, Donald; Tuukkanen, Sampo


    Pigment-cellulose nanofibril (PCN) composites were manufactured in a pilot line and used as a separator-substrate in printed graphene and carbon nanotube supercapacitors. The composites consisted typically of 80% pigment and 20% cellulose nanofibrils (CNF). This composition makes them a cost-effective alternative as a substrate for printed electronics at high temperatures that only very special plastic films can nowadays stand. The properties of these substrates can be varied within a relatively large range by the selection of raw materials and their relative proportions. A semi-industrial scale pilot line was successfully used to produce smooth, flexible, and nanoporous composites, and their performance was tested in a double functional separator-substrate element in supercapacitors. The nanostructural carbon films printed on the composite worked simultaneously as high surface area active electrodes and current collectors. Low-cost supercapacitors made from environmentally friendly materials have significant potential for use in flexible, wearable, and disposable low-end products. [Figure not available: see fulltext.

  4. Application of Vat Green 1 dye on gamma ray treated cellulosic fabric (United States)

    Bhatti, Ijaz Ahmad; Adeel, Shahid; Taj, Hina


    For the present study, Vat Green 1 dye has been selected for dyeing gamma irradiated cellulosic fabric. The dyeing variables such as dyeing temperature, dyeing time and dyeing pH were optimized. Concentrations of sodium hydrosulphite for reduction process and hydrogen peroxide for oxidation process were also optimized. After evaluation of dyed fabrics in a CIE Lab system using Spectraflash SF-650 it has been found that 6 kGy is the effective absorbed dose for improvement in dyeing behaviour of cellulosic fabric. Good colour strength has been obtained by dyeing optimal irradiated fabric (6 kGy, IC) at 75 °C for 1 h. by employing dyeing solution of pH 11. It has also been found that gamma ray treatment has reduced the necessary quantity of reducing (NaHSO3) and oxidizing agents (H2O2). The rating results after implementation of suggested standard methods of ISO for colourfastness showed that using irradiated textiles, the fastness to light, washing and rubbing has been significantly improved.

  5. Fusion d'images multi-modales pour la radiothérapie conformationnelle : application au repositionnement du patient



    Le traitement des cancers par radiothérapie externe met en .uvre un environnement complexe. L'irradiation doit être le plus possible limitée au volume tumoral, en évitant au maximum les tissus et organes sains avoisinants. L'utilisation de logiciels dosimétriques en trois dimensions permet d'adapter exactement la balistique d'irradiation à la forme de la tumeur. Le patient est replacé à chaque séance de son traitement dans la même position pour permettre de reproduire avec précision la balist...

  6. Application du système d’information géographique pour les réseaux GSM.



    Notre projet consiste à expliquer le fonctionnement du réseau GSM et de ses différents composants avec leurs différentes architectures on a parlé aussi du Drive Test ainsi que ses différents outils de mesures dans le but de trouve le chemin optimal autour de l’antenne BTS pour trouver le meilleur signal possible émis par l’antenne, ensuite on a parlé des systèmes d’informations géographiques qui ont une importance primordial dans la représen...

  7. Application of the triolein-embedded cellulose acetate membrane passive sampler for monitoring of polycyclic aromatic hydrocarbons in water. (United States)

    Tang, Jianfeng; He, Guiying; Li, Gang


    Triolein-embedded cellulose acetate membrane (TECAM) can be used as a passive sampler to measure hydrophobic organic contaminants in water. Uptake constant rates (k u ) for polycyclic aromatic hydrocarbons (PAHs) by TECAM sampling were measured under different hydrodynamic conditions. The measured k u values were modeled to enable the quantification of time weighed average (TWA) concentrations of PAHs in the field. An empirical relationship that enables the calculation of in situ k u values of chemicals using performance reference compounds (PRCs) was derived and its application was demonstrated in a field study. The results showed that freely dissolved concentrations of hydrophobic organic compounds (HOCs) can be accurately measured in the field using TECAM method based on empirical uptake models calibrated with PRCs.

  8. Cellulose Acetate Sulfate as a Lyotropic Liquid Crystalline Polyelectrolyte: Synthesis, Properties, and Application

    Directory of Open Access Journals (Sweden)

    D. D. Grinshpan


    Full Text Available The optimal conditions of cellulose acetate sulfate (CAS homogeneous synthesis with the yield of 94–98 wt.% have been determined. CAS was confirmed to have an even distribution of functional groups along the polymer chain. The polymer was characterized by an exceptionally high water solubility (up to 70 wt.%. The isothermal diagrams of its solubility in water-alcohol media have been obtained. CAS aqueous solutions stability, electrolytic, thermal, and viscous properties have been defined. The main hydrodynamic characteristics such as intrinsic viscosity, Huggins constant, and crossover concentration have been evaluated. The parameters of polymer chain thermodynamic rigidity have been calculated. The formation of liquid crystalline structures in concentrated CAS solutions has been confirmed. CAS was recommended to be used as a binder for the medicinal forms of activated carbon and carbon sorbent for water treatment, hydrophilic ointment foundation.

  9. The cellulose resource matrix. (United States)

    Keijsers, Edwin R P; Yılmaz, Gülden; van Dam, Jan E G


    The emerging biobased economy is causing shifts from mineral fossil oil based resources towards renewable resources. Because of market mechanisms, current and new industries utilising renewable commodities, will attempt to secure their supply of resources. Cellulose is among these commodities, where large scale competition can be expected and already is observed for the traditional industries such as the paper industry. Cellulose and lignocellulosic raw materials (like wood and non-wood fibre crops) are being utilised in many industrial sectors. Due to the initiated transition towards biobased economy, these raw materials are intensively investigated also for new applications such as 2nd generation biofuels and 'green' chemicals and materials production (Clark, 2007; Lange, 2007; Petrus & Noordermeer, 2006; Ragauskas et al., 2006; Regalbuto, 2009). As lignocellulosic raw materials are available in variable quantities and qualities, unnecessary competition can be avoided via the choice of suitable raw materials for a target application. For example, utilisation of cellulose as carbohydrate source for ethanol production (Kabir Kazi et al., 2010) avoids the discussed competition with easier digestible carbohydrates (sugars, starch) deprived from the food supply chain. Also for cellulose use as a biopolymer several different competing markets can be distinguished. It is clear that these applications and markets will be influenced by large volume shifts. The world will have to reckon with the increase of competition and feedstock shortage (land use/biodiversity) (van Dam, de Klerk-Engels, Struik, & Rabbinge, 2005). It is of interest - in the context of sustainable development of the bioeconomy - to categorize the already available and emerging lignocellulosic resources in a matrix structure. When composing such "cellulose resource matrix" attention should be given to the quality aspects as well as to the available quantities and practical possibilities of processing the

  10. Chitosan-cellulose composite materials: Preparation, Characterization and application for removal of microcystin

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Chieu D., E-mail: [Department of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, WI 53201 (United States); Duri, Simon [Department of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, WI 53201 (United States); Delneri, Ambra; Franko, Mladen [Laboratory for Environmental Research, University of Nova Gorica, Vipavska 13, 5001 Nova Gorica (Slovenia)


    Highlights: •A novel and recyclable synthetic method using an ionic liquid, a Green Solvent. •Ecocomposite materials were synthesized from cellulose (CEL) and chitosan (CS). •Adding CEL into CS substantially increases tensile strength of the composite. •The composite is much better adsorbent for cyanotoxins than other materials. •The composite can be reused because adsorbed microcystin can be desorbed. -- Abstract: We developed a simple and one-step method to prepare biocompatible composites from cellulose (CEL) and chitosan (CS). [BMIm{sup +}Cl{sup −}], an ionic liquid (IL), was used as a green solvent to dissolve and prepare the [CEL + CS] composites. Since majority (>88%) of IL used was recovered for reuse by distilling the aqueous washings of [CEL + CS], the method is recyclable. XRD, FTIR, NIR, {sup 13}C CP-MAS-NMR and SEM were used to monitor the dissolution and to characterize the composites. The composite was found to have combined advantages of their components: superior mechanical strength (from CEL) and excellent adsorption capability for microcystin-LR, a deadly toxin produced by cyanobacteria (from CS). Specifically, the mechanical strength of the composites increased with CEL loading; e.g., up to 5× increase in tensile strength was achieved by adding 80% of CEL into CS. Kinetic results of adsorption confirm that unique properties of CS remain intact in the composite, i.e., it is not only a very good adsorbent for microcystin but also is better than all other available adsorbents. For example, it can adsorb 4× times more microcystin than the best reported adsorbent. Importantly, the microcystin adsorbed can be quantitatively desorbed to enable the composite to be reused with similar adsorption efficiency.

  11. Polymer blend of PLA/PHBV based bionanocomposites reinforced with nanocrystalline cellulose for potential application as packaging material. (United States)

    Dasan, Y K; Bhat, A H; Ahmad, Faiz


    The current research discusses the development of poly (lactic acid) (PLA) and poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) reinforced nanocrystalline cellulose bionanocomposites. The nanocrystalline cellulose was derived from waste oil palm empty fruit bunch fiber by acid hydrolysis process. The resulting nanocrystalline cellulose suspension was then surface functionalized by TEMPO-mediated oxidation and solvent exchange process. Furthermore, the PLA/PHBV/nanocrystalline cellulose bionanocomposites were produced by solvent casting method. The effect of the addition of nanocrystalline cellulose on structural, morphology, mechanical and barrier properties of bionanocomposites was investigated. The results revealed that the developed bionanocomposites showed improved mechanical properties and decrease in oxygen permeability rate. Therefore, the developed bio-based composite incorporated with an optimal composition of nanocrystalline cellulose exhibits properties as compared to the polymer blend.

  12. Chimie du glycérol pour la synthèse de dérivés du glycérol applicables comme solvants ou diluants réactifs


    Sambou, Sophie


    Confrontés aux problèmes des composés organiques volatils et des solvants toxiques notamment les éthers de glycol, nous avons exploité cette opportunité pour développer la synthèse de dérivés de glycérol. Deux familles de dérivés du glycérol ont été retenus : les éthers de glycérol à chaîne alkyle courte (C1-C3) pour une application en tant que solvant et les acrylates et méthacrylates de glycérol pour une application en tant que diluants réactifs. Une approche de synthèse dirigée a consisté ...

  13. Hydroxypropyl methyl cellulose grafted with polyacrylamide: application in controlled release of 5-amino salicylic acid. (United States)

    Das, Raghunath; Pal, Sagar


    In the present study, hydroxypropyl methyl cellulose grafted with polyacrylamide (HPMC-g-PAM) hydrogel was evaluated in vitro as a potential carrier for controlled release of 5-amino salicylic acid (5-ASA). The graft copolymer was developed by grafting PAM chains onto HPMC backbone using potassium persulphate as initiator. The swelling behaviour of hydrogel based tablet was investigated as a function of pH and time in various buffer solutions similar to that of gastric and intestinal fluids. The % equilibrium swelling was found to be higher in case of simulated intestinal fluid (pH=7.4) and lower in simulated gastric fluid (pH=1.2), making an ideal matrix as required for colon specific drug delivery. The drug release study was performed at various pH values akin to the condition of GI tract. The release kinetics of 5-ASA showed non-Fickian diffusion behaviour. This indicates that the release is controlled by a combination of polymer relaxation or erosion of the matrix and diffusion of the drug from the swollen matrix.

  14. Biotemplated preparation of CdS nanoparticles/bacterial cellulose hybrid nanofibers for photocatalysis application. (United States)

    Yang, Jiazhi; Yu, Junwei; Fan, Jun; Sun, Dongping; Tang, Weihua; Yang, Xuejie


    In this work, we describe a novel facile and effective strategy to prepare micrometer-long hybrid nanofibers by deposition of CdS nanoparticles onto the substrate of hydrated bacterial cellulose nanofibers (BCF). Hexagonal phase CdS nanocrystals were achieved via a simple hydrothermal reaction between CdCl(2) and thiourea at relatively low temperature. The prepared pristine BCF and the CdS/BCF hybrid nanofibers were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis absorption spectroscopy (UV-vis), and X-ray photoelectron spectroscopy (XPS). The results reveal that the CdS nanoparticles were homogeneously deposited on the BCF surface and stabilized via coordination effect. The CdS/BCF hybrid nanofibers demonstrated high-efficiency photocatalysis with 82% methyl orange (MO) degradation after 90 min irradiation and good recyclability. The results indicate that the CdS/BCF hybrid nanofibers are promising candidate as robust visible light responsive photocatalysts.

  15. Application of Flumethrin Pour-On on Reservoir Dogs and Its Efficacy against Sand Flies in Endemic Focus of Visceral Leishmaniasis, Meshkinshahr, Iran

    Directory of Open Access Journals (Sweden)

    MohammadReza Jalilnavaz


    Full Text Available Background: Visceral leishmaniasis (VL is one of the most important parasitic zoonotic diseases in the world. Do­mestic dogs are the main domestic reservoirs of VL in endemic foci of Iran. Various methods, including vaccination, treatment of dogs, detection and removal of infected dogs have different results around the world. General policy on control of canine visceral leishmaniasis is protection of them from sand fly bites. The aim of this study was evalua­tion of pour-on application of flumethrin on dogs against blood-feeding and mortality of field-caught sand flies.Methods: Once every 20 days from May untill September 2013, the treated and control dogs were exposed with field caught sandflies for 2 hours under bed net traps. After the exposure time, both alive and dead sand flies were trans­ferred in netted cups to the laboratory. The mortality rate of them was assessed after 24 hours. The blood-fed or un­fed conditions were determined 2 hours after exposure to the dogs under stereomicroscope.Results: The blood feeding index was varied from 12.0 to 25.0 % and 53.0 to 58.0 % for treated and control dogs respectively (P< 0.0001. The blood feeding inhibition was 75.0–87.0 % and 41.0–46.0 % for the control and treated dogs (P< 0.0001, respectively.The total mortality rate was 94.0–100 % and 19.0–58.0 % respectively for the treated and control groups (P< 0.001.Conclustion: Application of pour-on flumethrin on dogs caused 90–100 % mortality until 2.5 month and inhibited the blood-feeding of sand flies. 



    E. K. Gladysheva; E. A. Skiba


    Summary: Bacterial cellulose is an organic material that is synthesized by microorganisms extracellularly. Bacterial cellulose can be used in various industries. Especially, bacterial cellulose has found its application basically in medicine. The production of bacterial cellulose is a complicated and long process. The principal criterion for the process to be successful is bacterial cellulose to be obtained in a higher yield. Russia is lacking an operating facility to produce bacterial cellul...

  17. Cellulose acetate fibers covered by CdS nanoparticles for hybrid solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Cortina, Hugo; Martinez-Alonso, Claudia [Centro de Investigacion en Energia, UNAM, Priv. Xochicalco S/N, Temixco, Morelos 62580 (Mexico); Castillo-Ortega, Monica [Universidad de Sonora, Hermosillo, Sonora 83000 (Mexico); Hu, Hailin, E-mail: [Centro de Investigacion en Energia, UNAM, Priv. Xochicalco S/N, Temixco, Morelos 62580 (Mexico)


    In this work cellulose acetate (CA) fibers with a diameter of approximately 1 {mu}m were immersed in a cadmium sulfide (CdS) precursor solution. After 3 h the original white color CA fibers became yellow and maintained the same form, suggesting the deposition of CdS on fiber surface. SEM images showed that CA fibers were covered by uniformly sized CdS nanoparticles of approximately 100 nm. XRD and optical absorption spectra indicated that they contained mostly cubic crystalline phase with the optical band gap of 2.43 eV. CdS coated CA fibers, called CdS(CA) fibers, were dispersed in a polar dispersant (dimethyl sulfoxide, DMSO) and then mixed with a poly(3-hexylthiophene) (P3HT) solution in a non-polar solvent (dichlorobenzene, DCB). The mixture was cast onto a transparent conductive glass substrate (Indium-Tin-Oxide, ITO), and after solvent evaporation a thin layer of CdS(CA)-P3HT composite was formed. It is observed that the volume relation between the polar dispersant and non-polar solvent influences the solubility of the P3HT product in the composite coating and the photovoltaic performance of the corresponding cell as well. The mass ratio between CdS(CA) fibers and P3HT in the composite layer affects the optical absorption of the composite. The best photovoltaic performance was obtained in CdS(CA)-P3HT based cells with a volume relation between DCB and DMSO of 3.5-1, a mass ratio between CdS(CA) and P3HT of 1:1, and a rapid drying process for composite coatings.

  18. [Application of high-efficient cellulose utilization microorganisms in co-composting of vegetable wastes and flower stalk]. (United States)

    Huang, De-yang; Lu, Wen-jing; Wang, Hong-tao; Zhou, Hui-yu; Wang, Zhi-chao


    An inoculation composing 17 species of cellulose utilization microorganisms was used in co-composting of vegetable wastes and flower stalk, and the efficiency of the inoculation on lignocellulose degradation was studied. The experiments result show that at the beginning of the first stage of composting, inoculating cellulose utilization microorganism in the substrates with 0.5% (V/V) can improve the biomass of the microorganisms into the substrates greatly and make them dominant ones. When the temperature was controlled as 55 degrees C, the biomass of cellulose utilization microorganisms can keep between [symbol: see text] 3.84 x 10(9)-1.80 x 10(10) CFU/g. At the beginning of the second stage, inoculating with 1% (V/V) can improve the temperature during this period effectively. Monitoring of the content of lignocelluloses in the substrate shows that the inoculation of cellulose utilization microorganism can accelerate the degradation of cellulose. The degradation efficiency of cellulose under inoculation condition is 23.64% higher than those without inoculation. This shows that inoculating with cellulose utilization microorganisms in each stage of the composting can greatly decompose the lignocellulose in the substrates, accelerate the co-composting process and improve the quality of composting production.

  19. ARC Code TI: Pour (United States)

    National Aeronautics and Space Administration — Pour is a general-purpose information service framework designed to accommodate a wide variety of information types with support for high volume, low frequency...

  20. Simultaneously Tailoring Surface Energies and Thermal Stabilities of Cellulose Nanocrystals Using Ion Exchange: Effects on Polymer Composite Properties for Transportation, Infrastructure, and Renewable Energy Applications. (United States)

    Fox, Douglas M; Rodriguez, Rebeca S; Devilbiss, Mackenzie N; Woodcock, Jeremiah; Davis, Chelsea S; Sinko, Robert; Keten, Sinan; Gilman, Jeffrey W


    Cellulose nanocrystals (CNCs) have great potential as sustainable reinforcing materials for polymers, but there are a number of obstacles to commercialization that must first be overcome. High levels of water absorption, low thermal stabilities, poor miscibility with nonpolar polymers, and irreversible aggregation of the dried CNCs are among the greatest challenges to producing cellulose nanocrystal-polymer nanocomposites. A simple, scalable technique to modify sulfated cellulose nanocrystals (Na-CNCs) has been developed to address all of these issues. By using an ion exchange process to replace Na(+) with imidazolium or phosphonium cations, the surface energy is altered, the thermal stability is increased, and the miscibility of dried CNCs with a nonpolar polymer (epoxy and polystyrene) is enhanced. Characterization of the resulting ion exchanged CNCs (IE-CNCs) using potentiometry, inverse gas chromatography, dynamic vapor sorption, and laser scanning confocal microscopy reveals that the IE-CNCs have lower surface energies, adsorb less water, and have thermal stabilities of up to 100 °C higher than those of prepared protonated cellulose nanocrystals (H-CNCs) and 40 °C higher than that of neutralized Na-CNC. Methyl(triphenyl)phosphonium exchanged cellulose nanocrystals (MePh3P-CNC) adsorbed 30% less water than Na-CNC, retained less water during desorption, and were used to prepare well-dispersed epoxy composites without the aid of a solvent and well-dispersed polystyrene nanocomposites using a melt blending technique at 195 °C. Predictions of dispersion quality and glass transition temperatures from molecular modeling experiments match experimental observations. These fiber-reinforced polymers can be used as lightweight composites in transportation, infrastructure, and renewable energy applications.

  1. Development of new phosphated cellulose for application as an efficient biomaterial for the incorporation/release of amitriptyline. (United States)

    Bezerra, Roosevelt D S; Morais, Alan I S; Osajima, Josy A; Nunes, Livio C C; Silva Filho, Edson C


    In the last years has increased the study about the using of natural biopolymers and theirs derivatives in the removal (adsorption/incorporation) of contaminats of medium aqueous, and theirs utilization in the desorption (release) de drugs. However, there not in the literature studies about the utilization of the cellulose and cellulose phosphate in the adsorption (incorporation)/desorption (release) of the drug amitriptyline (AMI). Therefore, in this study was accomplished the synthesized of the phosphated cellulose (PC) through the reaction of pure cellulose (C) with sodium trimetaphosphate (P) under-reflux, for 4h and at 393K. The efficiency of the reaction was observed by XRD, TG/DTG, (31)P NMR and EDS. The adsorption study for the AMI in aqueous medium was carried out by varying the time, pH, concentration, temperature and ionic strength. The results showed that the PC showed a greater adsorption capacity of AMI than pure cellulose, presenting an increase of about 102.72% in the adsorption capacity of the drug by cellulose after the phosphating reaction. In desorption of drug from the surface of biomaterials was performed by varying the pH and time, where it was observed that PC showed a maximum release of 40.98% ± 0.31% at pH 7.

  2. Application of Box-Behnken Design in Optimization of Glucose Production from Oil Palm Empty Fruit Bunch Cellulose

    Directory of Open Access Journals (Sweden)

    Satriani Aga Pasma


    Full Text Available Oil palm empty fruit bunch fiber (OPEFB is a lignocellulosic waste from palm oil mills. It contains mainly cellulose from which glucose can be derived to serve as raw materials for valuable chemicals such as succinic acid. A three-level Box-Behnken design combined with the canonical and ridge analysis was employed to optimize the process parameters for glucose production from OPEFB cellulose using enzymatic hydrolysis. Organosolv pretreatment was used to extract cellulose from OPEFB using ethanol and water as the solvents. The extracted cellulose was characterized by thermogravimetric analysis, FTIR spectroscopy, and field emission scanning electron microscopy. Hydrolysis parameters including amount of enzyme, amount of cellulose, and reaction time were investigated. The experimental results were fitted with a second-order polynomial equation by a multiple regression analysis and found that more than 97% of the variations could be predicted by the models. Using the ridge analysis, the optimal conditions reaction time found for the production of glucose was 76 hours and 30 min, whereas the optimum amount of enzyme and cellulose was 0.5 mL and 0.9 g, respectively. Under these optimal conditions, the corresponding response value predicted for glucose concentration was 169.34 g/L, which was confirmed by validation experiments.

  3. Cellulose Insulation (United States)


    Fire retardant cellulose insulation is produced by shredding old newspapers and treating them with a combination of chemicals. Insulating material is blown into walls and attics to form a fiber layer which blocks the flow of air. All-Weather Insulation's founders asked NASA/UK-TAP to help. They wanted to know what chemicals added to newspaper would produce an insulating material capable of meeting federal specifications. TAP researched the query and furnished extensive information. The information contributed to successful development of the product and helped launch a small business enterprise which is now growing rapidly.

  4. Developpement et application d'un systeme mobile de laser terrestre pour quantifier le bilan sedimentaire des plages (United States)

    Van-Wierts, Stefanie

    Au Québec maritime, l'érosion côtière est une problématique d'envergure, notamment sur les côtes de formations meubles. Les plages ont un rôle de zone tampon ayant comme fonction naturelle d'absorber l'énergie des vagues et donc d'assurer l'équilibre de certains écosystèmes et le maintien de l'écoumène en réduisant l'érosion de la côte. Les méthodes d'acquisition conventionnelles ne permettent pas de quantifier convenablement les changements morphosédimentaires d'une plage à l'échelle des cellules hydrosédimentaires. Le manque de méthode d'acquisition fiable et de données quantitatives mène à une surestimation ou à une sous-estimation de la disponibilité sédimentaire d'un système côtier. Pour contrer ces lacunes et afin de minimiser les coûts d'acquisition, un nouveau système mobile de LiDAR terrestre a été mis en place, permettant d'acquérir des données topographiques de l'estran, de la haute plage et des falaises. Le système multicapteurs comprend un LiDAR, un système de navigation à haute précision (IMU et D-GPS) et une caméra. L'ensemble des instruments et capteurs sont montés sur un véhicule de type tout-terrain. Le système a été évalué sur la zone côtière de la péninsule de Manicouagan. La comparaison des données LiDAR avec 1 050 points de référence géopositionnés au D-GPS montre une erreur verticale moyenne de 0,1 m sur les secteurs de plage. Les résultats montrent que le volume sédimentaire moyen des plages devant les zones où la ligne de rivage présente un ouvrage de protection en enrochement (12 m 3/m) est plus de trois fois plus faible que devant les secteurs à l'état naturel (35,5 m3/m). La moyenne des secteurs en transition, constituant les segments où une zone artificielle et une zone naturelle se chevauchent présentent un volume moyen de 28 m3/m. Aussi, les plages devant les secteurs anthropisés sont en moyenne près de 2 fois plus étroites (12,7 m) que devant les secteurs naturels (25

  5. Nanomechanics of cellulose crystals and cellulose-based polymer composites (United States)

    Pakzad, Anahita

    Cellulose-polymer composites have potential applications in aerospace and transportation areas where lightweight materials with high mechanical properties are needed. In addition, these economical and biodegradable composites have been shown to be useful as polymer electrolytes, packaging structures, optoelectronic devices, and medical implants such as wound dressing and bone scaffolds. In spite of the above mentioned advantages and potential applications, due to the difficulties associated with synthesis and processing techniques, application of cellulose crystals (micro and nano sized) for preparation of new composite systems is limited. Cellulose is hydrophilic and polar as opposed to most of common thermoplastics, which are non-polar. This results in complications in addition of cellulose crystals to polymer matrices, and as a result in achieving sufficient dispersion levels, which directly affects the mechanical properties of the composites. As in other composite materials, the properties of cellulose-polymer composites depend on the volume fraction and the properties of individual phases (the reinforcement and the polymer matrix), the dispersion quality of the reinforcement through the matrix and the interaction between CNCs themselves and CNC and the matrix (interphase). In order to develop economical cellulose-polymer composites with superior qualities, the properties of individual cellulose crystals, as well as the effect of dispersion of reinforcements and the interphase on the properties of the final composites should be understood. In this research, the mechanical properties of CNC polymer composites were characterized at the macro and nano scales. A direct correlation was made between: - Dispersion quality and macro-mechanical properties - Nanomechanical properties at the surface and tensile properties - CNC diameter and interphase thickness. Lastly, individual CNCs from different sources were characterized and for the first time size-scale effect on

  6. Preparation of Cellulosic Membrane Containing Pyrrolidone Moiety Via Radiation Induced Grafting and its Application in Wastewater Treatment

    Directory of Open Access Journals (Sweden)

    A. S. Aly


    Full Text Available Radiation induced grafting of vinyl pyrrolidone onto cellulose wood pulp was carried out in heterogeneous and homogenous media using gamma radiation. Cellulose wood pulp was used in different forms; a in a homogenous solution by dissolving the wood pulp in N,N- dimethylacetamide/Lithium chloride (DMAc/LiCl mixture , b in a membrane form, by precipitating the cellulose solution in water and c in a powder form. Factors affecting on the grafting such as radiation dose, monomer concentration, precipitator concentration and thickness of the membrane have been studied. The result showed that at the same dose, the grafting yield was higher with cellulose in soluble form than in the membrane form, whereas cellulose in powder exhibited the lowest graft yield. The grafted membrane was characterized by IR, TGA and SEM. The ability of the grafted membrane to remove dyes (acid and basic dye, heavy metal ions (Co 2+ , Ni 2+ and Cu 2+ and phenols from wastewater was also reported.

  7. Approches anatomique et par imagerie des nerfs du plexus brachial : application pour le bloc échoguidé lors de chirurgie de l'épaule


    Zoccarato, Sophie


    La technique d’anesthésie loco-régionale est de plus en plus employée en per-opératoire pour optimiser l’analgésie. Chez le chien, différents blocs axillaires ont déjà montré leurs intérêts pour des chirurgies du membre thoracique. Cependant, lors de chirurgie de la région de l’épaule, seul un bloc paravertébral du plexus brachial est efficace pour anesthésier cette région. Une étude méticuleuse de l’anatomie a permis d’établir les rameaux ventraux des nerfs spinaux à anesthésier pour réussir...

  8. Using cloud-computing applications to support collaborative scientific inquiry: Examining pre-service teachers’ perceived barriers towards integration / Utilisation d'applications infonuagiques pour appuyer la recherche scientifique collaborative

    Directory of Open Access Journals (Sweden)

    Joel Donna


    Full Text Available Technology plays a crucial role in facilitating collaboration within the scientific community. Cloud-computing applications can be used to model such collaboration and support inquiry within the secondary science classroom. Little is known about pre-service teachers’ beliefs related to the envisioned use of this technology in their teaching. These beliefs may influence future integration. This study finds several first-order barriers, such as perceptions that these tools would take too much time to use. Second-order barriers include perceptions that this technology would not promote face-to-face collaboration skills, would create social loafing situations, and beliefs that the technology does not help students understand the nature of science. Suggestions for mitigating these barriers within pre-service education technology courses are discussed. La technologie joue un rôle essentiel pour faciliter la collaboration au sein de la communauté scientifique. Les applications infonuagiques telles que Google Drive peuvent être utilisées pour donner forme à ce type de collaboration et pour appuyer le questionnement dans les cours de sciences du secondaire. On connaît pourtant peu les opinions que se font les futurs enseignants d’une telle utilisation des technologies collaboratives infonuagiques. Or, ces opinions pourraient influencer l’intégration future de ces technologies en salle de classe. Cette étude révèle plusieurs obstacles de premier plan, comme l’idée que l’utilisation de ces outils informatiques prend trop de temps. Parmi les obstacles de second plan, on note les perceptions selon lesquelles cette technologie ne promeut pas les compétences collaboratives de personne à personne, pose des problèmes de gestion de classe et n'aide pas les étudiants à comprendre la nature de la science. Des suggestions sont proposées pour atténuer ces obstacles dans les cours de technologie des programmes d’éducation.

  9. Comparison of physical properties of regenerated cellulose films fabricated with different cellulose feedstocks in ionic liquid. (United States)

    Pang, JinHui; Wu, Miao; Zhang, QiaoHui; Tan, Xin; Xu, Feng; Zhang, XueMing; Sun, RunCang


    With the serious "white pollution" resulted from the non-biodegradable plastic films, considerable attention has been directed toward the development of renewable and biodegradable cellulose-based film materials as substitutes of petroleum-derived materials. In this study, environmentally friendly cellulose films were successfully prepared using different celluloses (pine, cotton, bamboo, MCC) as raw materials and ionic liquid 1-ethyl-3-methylimidazolium acetate as a solvent. The SEM and AFM indicated that all cellulose films displayed a homogeneous and smooth surface. In addition, the FT-IR and XRD analysis showed the transition from cellulose I to II was occurred after the dissolution and regeneration process. Furthermore, the cellulose films prepared by cotton linters and pine possessed the most excellent thermal stability and mechanical properties, which were suggested by the highest onset temperature (285°C) and tensile stress (120 MPa), respectively. Their excellent properties of regenerated cellulose films are promising for applications in food packaging and medical materials.

  10. Cellulose Synthases and Synthesis in Arabidopsis

    Institute of Scientific and Technical Information of China (English)

    Anne Endler; Staffan Persson


    Plant cell walls are complex structures composed of high-molecular-weight polysaccharides,proteins,and lignins. Among the wall polysaccharides,cellulose,a hydrogen-bonded β-1,4-linked glucan microfibril,is the main load-bearing wall component and a key precursor for industrial applications. Cellulose is synthesized by large multi-meric cellulose synthase (CesA) complexes,tracking along cortical microtubules at the plasma membrane. The only known components of these complexes are the cellulose synthase proteins. Recent studies have identified tentative interaction partners for the CesAs and shown that the migratory patterns of the CesA complexes depend on phosphorylation status. These advances may become good platforms for expanding our knowledge about cellulose synthesis in the near future. In addition,our current understanding of cellulose chain polymerization in the context of the CesA complex is discussed.

  11. Nucleic acids encoding a cellulose binding domain

    Energy Technology Data Exchange (ETDEWEB)

    Shoseyov, Oded (Karmey Yosef, IL); Shpiegl, Itai (Rehovot, IL); Goldstein, Marc A. (Davis, CA); Doi, Roy H. (Davis, CA)


    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  12. Advanced and Integrated Petrophysical Characterization for CO2 Storage: Application to the Ketzin Site Caractérisation pétrophysique intégrée pour le stockage de CO2 : application au site de Ketzin

    Directory of Open Access Journals (Sweden)

    Fleury M.


    from 100 to 300 mD. Two zones were identified on the logs characterized by two different irreducible saturation ranging from 15 up to 35%. The measured relative permeability curves show a sharp decrease of the water effective permeability and suggest that a saturation lower than 50% cannot be reached in practice. The exponent of the resistivity index curve is about 1.7, lower than the default value of 2. The caprock has a permeability of 27 nD, a porosity around 15% and a pore diffusivity of 0.8 x 10-9 m2/s La simulation et le suivi d’un stockage de CO2 requiert des données pétrophysiques spécifiques. Nous présentons un ensemble d’expériences applicables à tout stockage et à toute couverture, fournissant des données pour des simulations numériques réalistes du potentiel de stockage et de l’injection. Ces expériences sont intégrées avec les données diagraphiques pour l’estimation de la porosité, la saturation irréductible, la pression capillaire et la perméabilité relative de l’eau en drainage, la saturation en gaz résiduelle, les relations résistivité-saturation et les propriétés de transport de la couverture (perméabilité et diffusivité. Le cas considéré est l’aquifère salin du Trias dans le contexte du projet CO2SINK, le premier site expérimental de stockage en Allemagne situé près de Ketzin. Nous avons utilisé des méthodes de mesure nécessitant des durées raisonnables tout en restant représentatives des processus in situ. Pour le transport diphasique, nous avons utilisé la centrifugation. Pour la résistivité, nous avons utilisé une méthode rapide « Fast Resistivity Index Measurement » (FRIM en drainage et imbibition, en condition ambiante et en condition de stockage. Pour la caractérisation de la couverture, nous avons utilisé une technique rapide RMN (Résonance Magnétique Nucléaire utilisant le deutérium comme traceur pour la mesure de diffusion et une méthode stationnaire innovante pour la mesure de

  13. Plasma induit par laser sur des matériaux organiques et applications pour discrimination et identification de plastiques


    Boueri, Myriam


    Laser-Induced Breakdown Spectroscopy (LIBS) is an analytical technique that has the potential to detect all the elements present in the periodic table. The limit of detection can go below a few ppm and this regardless of the physical phase of the analyzed sample (solid, liquid or gas). Its simplicity of use, its rapidity to get results and its versatility provide this technique with attractive features. The technique is currently developed for applications in a large number of domains such as...

  14. Etude de nano-transistors à faible pente sous le seuil pour des applications très basse consommation


    Villalon, Anthony


    Band to band tunneling field effect transistor (TFET) is a PIN-gated architecture able to reach sub 60mV/dec subthreshold slopes at room temperature, which is an advantage over MOSFET in low power applications. The objective of this thesis is to study and characterize TFETs fabricated in CEA-LETI using MOSFET SOI technology. The first generation of devices is realized on planar FDSOI technology, and studies the impact of source/channel heterojunction, channel thickness and annealing temperatu...

  15. Application d'une technique de modelisation aerodynamique conceptuelle sur la simulation d'un pilote automatique a commande optimale pour un avion d'affaires (United States)

    Pollender-Moreau, Olivier

    Ce document présente, dans le cadre d'un contexte conceptuel, une méthode d'enchaînement servant à faire le lien entre les différentes étapes qui permettent de réaliser la simulation d'un aéronef à partir de ses données géométriques et de ses propriétés massiques. En utilisant le cas de l'avion d'affaires Hawker 800XP de la compagnie Hawker Beechcraft, on démontre, via des données, un processus de traitement par lots et une plate-forme de simulation, comment (1) modéliser la géométrie d'un aéronef en plusieurs surfaces, (2) calculer les forces aérodynamiques selon une technique connue sous le nom de Vortex Lattice Method, (3) construire un modèle de vol servant à la simulation des aéronefs pour leur enveloppe de vol en ajoutant des fonctions supplémentaires, (4) construire un modèle de turbosoufflante simplifié, (5) développer un algorithme d'équilibre (trim) du mouvement longitudinal, (6) développer des algorithmes de contrôle à commande moderne, (7) développer certaines fonctions d'un système de pilotage automatique, et (8) rassembler le tout sous une même plate-forme de simulation. Afin de supporter ce travail, une application publique Matlab, connue sous le nom de Tornado, est utilisée conjointement avec d'autres fonctions pour la conception du modèle de vol aérodynamique. D'ailleurs, il sera démontré que le modèle de vol, quoiqu'il soit quand même crédible, ne concorde pas tout à fait avec les données de référence. Par contre, puisque le modèle des moteurs fonctionne bien, que l'algorithme d'équilibrage du mouvement longitudinal fonctionne bien et que les pôles des systèmes dynamiques concordent avec la littérature, les tests dynamiques effectués au sein de la plate-forme de simulation permettent d'obtenir des résultats fonctionnels et crédibles. D'ailleurs, deux systèmes d'augmentation de la stabilité basés sur la méthode de contrôle moderne LQR et couvrant l'enveloppe de vol de l'aéronef via un



    Cieslak, Jérôme


    This thesis discusses the design of an active Fault Tolerant Control (FTC) strategy for improvement of the operational control capability of the safety critical systems. The FTC strategy works in such a way that once a fault is detected by the Fault Detection and Isolation (FDI) unit, a compensation loop is activated for safe recovery. A key feature of the proposed strategy is that the design of the FTC loop is done independently of the nominal control law already in place. For a given applic...

  17. Obstacle detection contribution for automotive applications; Contribution a la detection d'obstacles pour la voiture intelligente

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, M.


    On the one hand, this Ph-D Thesis deals with a new architectural approach for automotive applications implementing heterogeneous sensor data fusion, and on the other hand, it explains the data pre-processing algorithm of a microwave radar. Firstly, the analysis of both PROCHIP2 and PROLAB2 obstacle detection demonstrators (cf. the European PROMETHEUS research program about smart cars) has led us to propose a new functional architecture. Our approach introduces a sensor data pre-processing level. Data are then running at the local sensor before being transferred to data fusion architectures (that classically receives data whose meaning has also been noised by the application distribution). Secondly, an elementary simulator has been designed in order to complement our database composed of experimental microwave radar data. It is able to generate radar data for basic highway traffic scenarios. With both experimental and simulated data, a deterministic radar data pre-processing algorithm has been designed. It reduces the amount of data to be transferred by converting the local radar data into a higher semantic information: it gives more pertinent data (for example: velocities...) to the data fusion level; in particular, it predicts the obstacle path. Finally, some perspectives have been set out. Firstly, an H {infinity} estimation approach is used to reduce the data disruption effect that alters the radar data and, secondly, a controller has been proposed with the goal of decreasing the effect of car pitching. (author)

  18. Cellulose metabolism in plants. (United States)

    Hayashi, Takahisa; Yoshida, Kouki; Park, Yong Woo; Konishi, Teruko; Baba, Kei'ichi


    Many bacterial genomes contain a cellulose synthase operon together with a cellulase gene, indicating that cellulase is required for cellulose biosynthesis. In higher plants, there is evidence that cell growth is enhanced by the overexpression of cellulase and prevented by its suppression. Cellulase overexpression could modify cell walls not only by trimming off the paracrystalline sites of cellulose microfibrils, but also by releasing xyloglucan tethers between the microfibrils. Mutants for membrane-anchored cellulase (Korrigan) also show a typical phenotype of prevention of cellulose biosynthesis in tissues. All plant cellulases belong to family 9, which endohydrolyzes cellulose, but are not strong enough to cause the bulk degradation of cellulose microfibrils in a plant body. It is hypothesized that cellulase participates primarily in repairing or arranging cellulose microfibrils during cellulose biosynthesis in plants. A scheme for the roles of plant cellulose and cellulases is proposed.

  19. SnAg-alloy coating for connectors and soldering applications; Alliages SnAg pour revetements de connecteurs et brasage

    Energy Technology Data Exchange (ETDEWEB)

    Buresch, I. [Wieland-Werke AG, Ulm (Germany)


    The announced ban of lead in electronic products (WEEE-Waste Electrical and Electronic Equipment from 2006 onwards) is one chance to implement better alternatives. It is a challenge for researcher to develop one alternative which fulfills the different requirements for conditions in use for connectors and production like soldering. The system SnAgCu gives us.good opportunities for soldering applications and as a coating material for connectors. The tin-silver-copper alloy SnTOP meets the engine compartment requirements in automobiles in terms of temperature exposure while simultaneously provide low insertion forces using it as a functional coating on connectors combined with good solderability using it as a solder. (authors)

  20. Fermentation Tecniques and Applications of Bacterial Cellulose: a Review Técnicas de fermentación y aplicaciones de la celulosa bacteriana: una revisión

    Directory of Open Access Journals (Sweden)

    Luz Dary Carreño Pineda


    Full Text Available Bacterial cellulose is a polymer obtained by fermentation with microorganismsfrom Acetobacter, Rhizobium, Agrobacterium and Sarcina genera. Amongthem, Acetobacter xylinum is the most efficient specie. This polymer hasthe same chemical composition of plant cellulose, but its conformation andphysicochemical properties are different, making it attractive for several applications, especially in the areas of food, separation processes, catalysis andhealth, due to its biocompatibility. However, the main problem is the production in mass that is constrained by low yield. It is therefore necessaryto develop some alternatives. This paper presents a review about synthesis,production, properties and principal applications of bacterial cellulose, as wellas some alternatives to reduce the difficulties for process scaling.La celulosa bacteriana es un polímero obtenido por fermentación con microrganismosde los géneros Acetobacter, Rhizobium, Agrobacterium y Sarcina, delas cuales la especie más eficiente es la Acetobacter Xylinum. Este polímero presenta la misma estructura química de la celulosa de origen vegetal, pero difiereen su conformación y propiedades fisicoquímicas, lo que lo hace atractivo para diversas aplicaciones, especialmente en las áreas de alimentos, procesosde separación, catálisis y en medicina, gracias a su biocompatibilidad. Sin embargo, el principal problema es la producción a gran escala limitada por losbajos rendimientos, lo que genera la necesidad de desarrollar alternativas que permitan disminuir o eliminar las causas de esta limitación. En este artículo se hace una revisión acerca de la síntesis, producción, propiedades y principales aplicaciones de la celulosa bacteriana, así como de algunas alternativas estudiadas para disminuir los inconvenientes en el escalamiento del proceso.

  1. Implications of Multilingual Interoperability of Speech Technology for Military Use (Les implications de l’interoperabilite multilingue des technologies vocales pour applications militaires) (United States)


    duration. Such Technical Teams can organise workshops, symposia, field trials, lecture series and training courses . An important function of these...termes de recherche anglais . Pour de telles raisons, un groupe de travail de l’Organisation pour la recherche et la technologie de l’OTAN (RTO) a lancé...recueillies au cours de cette étude ont été diffusées à l’ensemble des pays de l’OTAN participants, et la plupart d’entre elles sont disponibles sous

  2. Application des techniques multiporteuses de type OFDM pour les futurs systèmes de télécommunications par satellite


    Ho, Anh Tai


    Cette thèse étudie la possibilité d'appliquer les techniques de modulations multiporteuses de type OFDM dans les futurs systèmes de communications par satellite. Elle traite notamment du problème de synchronisation au niveau récepteur pour les systèmes de diffusion par satellite en bande Ka. L'objectif est de proposer une structure de réception ayant besoin du moins de ressources possibles pour synchroniser afin d'optimiser l'efficacité spectrale du système et obtenir un gain par rapport à un...

  3. Offre pour nos membres

    CERN Multimedia

    Staff Association


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  4. Influence of sheep breed and application site on the efficacy of a flumethrin pour-on formulation against ticks

    Directory of Open Access Journals (Sweden)

    L.J. Fourie


    Full Text Available The objectives of this study were to determine the influence of application site and sheep breed on the efficacy of a flumethrin (1 % m/v solution for the control of 'bont'-legged (Hyalomma spp. and red-legged ticks (Rhipicephalus evertsi evertsi. This study was conducted from November 1996 to February 1997 on 3 farms in the southwestern Free State Province. Two trials were conducted on Dorper sheep and 2 on Merino sheep. For each specific application 30 sheep were selected and allocated to 3 groups of 10 animals each using randomisation through minimisation, with pre-treatment total tick count as only criterion. Groups consisted of an untreated control group, a group treated with 3 m of a flumethrin (1 % m/v solution applied only to the anogenital region, and a group treated at a dose rate of 1 m flumethrin (1% m/v/5 kg host body mass. The total dose volume for animals in the last group was divided into 3 equal parts and applied to the brisket/axillae, groin and anogenital regions respectively. Animals grazed under extensive farming conditions and were infested by ticks that occurred naturally in the environment. Ticks were counted and removed weekly over a 6-week period. In all 4 trials, Rhipicephalus e. evertsi was the dominant tick species, followed, in 3 of the trials, by Hyalomma spp. Efficacy (% of control against ticks for Dorper sheep, treated only on the anogenital region, was variable, ranging between 29.5 and 97 %. In Merino sheep the efficacy values ranged between 23.1 and 90 %. The site-spcific (anogenital region efficacy of control against ticks infesting Merino sheep was in general 100 % or almost 100 %. In Dorper sheep the efficacy values were >80 % for 3-5 weeks. The efficacy (% of control against ticks for sheep treated on the brisket/axillae, groin and anogenital regions was always higher compared to sheep treated only on the anogenital region. In Dorper sheep, efficacy of control was >80 % for up to 4 weeks and in Merino

  5. Development of nonflammable cellulosic foams (United States)

    Luttinger, M.


    The development of a moldable cellulosic foam for use in Skylab instrument storage cushions is considered. Requirements include density of 10 lb cu ft or less, minimal friability with normal handling, and nonflammability in an atmosphere of 70 percent oxygen and 30 percent nitrogen at 6.2 psia. A study of halogenated foam components was made, including more highly chlorinated binders, halogen-containing additives, and halogenation of the cellulose. The immediate objective was to reduce the density of the foam through reduction in inorganic phosphate without sacrificing flame-retarding properties of the foams. The use of frothing techniques was investigated, with particular emphasis on a urea-formaldehyde foam. Halogen-containing flame retardants were deemphasized in favor of inorganic salts and the preparation of phosphate and sulphate esters of cellulose. Utilization of foam products for civilian applications was also considered.

  6. Flexible, highly graphitized carbon aerogels based on bacterial cellulose/lignin: Catalyst-free synthesis and its application in energy storage devices

    KAUST Repository

    Xu, Xuezhu


    Currently, most carbon aerogels are based on carbon nanotubes (CNTs) or graphene, which are produced through a catalyst-assisted chemical vapor deposition method. Biomass based organic aerogels and carbon aerogels, featuring low cost, high scalability, and small environmental footprint, represent an important new research direction in (carbon) aerogel development. Cellulose and lignin are the two most abundant natural polymers in the world, and the aerogels based on them are very promising. Classic silicon aerogels and available organic resorcinol-formaldehyde (RF) or lignin-resorcinol-formaldehyde (LRF) aerogels are brittle and fragile; toughening of the aerogels is highly desired to expand their applications. This study reports the first attempt to toughen the intrinsically brittle LRF aerogel and carbon aerogel using bacterial cellulose. The facile process is catalyst-free and cost-effective. The toughened carbon aerogels, consisting of blackberry-like, core-shell structured, and highly graphitized carbon nanofibers, are able to undergo at least 20% reversible compressive deformation. Due to their unique nanostructure and large mesopore population, the carbon materials exhibit an areal capacitance higher than most of the reported values in the literature. This property makes them suitable candidates for flexible solid-state energy storage devices. Besides energy storage, the conductive interconnected nanoporous structure can also find applications in oil/water separation, catalyst supports, sensors, and so forth. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Des ballons pour demain (United States)

    Régipa, R.

    A partir d'une théorie sur la détermination des formes et des contraintes globales d'un ballon de révolution, ou s'en rapprochant, une nouvelle famille de ballons a été définie. Les ballons actuels, dits de ``forme naturelle'', sont calculés en général pour une tension circonférencielle nulle. Ainsi, pour une mission donnée, la tension longitudinale et la forme de l'enveloppe sont strictement imposées. Les ballons de la nouvelle génération sont globalement cylindriques et leurs pôles sont réunis par un câble axial, chargé de transmettre une partie des efforts depuis le crochet (pôle inférieur), directement au pôle supérieur. De plus, la zone latérale cylindrique est soumise à un faible champ de tensions circonférencielles. Ainsi, deux paramètres permettent de faire évoluer la distribution des tensions et la forme de l'enveloppe: - la tension du câble de liaison entre pôles (ou la longueur de ce câble) - la tension circonférencielle moyenne désirée (ou le rayon du ballon). On peut donc calculer et réaliser: - soit des ballons de forme adaptée, comme les ballons à fond plat pour le bon fonctionnement des montgolfières infrarouge (projet MIR); - soit des ballons optimisés pour une bonne répartition des contraintes et une meilleure utilisation des matériaux d'enveloppe, pour l'ensemble des programmes stratosphériques. Il s'ensuit une économie sensible des coûts de fabrication, une fiabilité accrue du fonctionnement de ces ballons et une rendement opérationnel bien supérieur, permettant entre autres, d'envisager des vols à très haute altitude en matériaux très légers.

  8. Pre-irradiation grafting of cellulose and slightly carboxymethylated cellulose (CMC) fibres

    Energy Technology Data Exchange (ETDEWEB)

    Benke, N. [Institute of Isotopes, HAS, Budapest (Hungary); Takacs, E. [Institute of Isotopes, HAS, Budapest (Hungary)]. E-mail:; Wojnarovits, L. [Institute of Isotopes, HAS, Budapest (Hungary); Borsa, J. [Budapest University of Technology and Economics, Budapest (Hungary)


    Acrylamide, hydroxypropyl acrylate, hydroxypropyl methacrylate and 2-ethylhexyl methacrylate vinyl monomers were grafted onto cellulose as well as onto cellulose of improved accessibility (slightly carboxymethylated cellulose (CMC)) by the pre-irradiation grafting technique. The effect of dose, monomer structure, crosslinking agent and carboxymethylation on the grafting yield was studied and the optimal conditions for the grafting were established. Grafting, with the exception of acrylamide (AAm), decreased the swelling of the samples, which is advantageous for some applications. In case of AAm decrease in swelling was observed only when crosslinking agent was applied. At low doses (<5 kGy) the high accessibility of carboxymethylated cellulose resulted in a higher grafting yield.

  9. Preparation of CeO2 Nanoparticles and Its Application to Ion-selective Electrodes Based on Acetyl Cellulose

    Institute of Scientific and Technical Information of China (English)


    CeO2 nanoparticles with an average diameter of about 30 nm were prepared by sol-gel method at lower temperature. The gel, transformed from the aqueous solution of metal nitrate and citric acid, can be combusted completely at lower temperature. The redox behavior and the crystallization process of the dried gel were studied by thermogravimetric analysis and infrared spectroscopy. The synthesized powders were characterized by X-ray powder diffraction and transmission electron microscopy. In addition, rare earth elements ion-selective electrodes based on acetyl cellulose were prepared using ultra fine cerium oxide powders.

  10. Characterization of cellulose nanowhiskers; Caracterizacao do nanowhiskers de celulose

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Nayra R.; Pinheiro, Ivanei F.; Morales, Ana R.; Ravagnani, Sergio P.; Mei, Lucia, E-mail: [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)


    Cellulose is the most abundant polymer earth. The cellulose nanowhiskers can be extracted from the cellulose. These have attracted attention for its use in nanostructured materials for various applications, such as nanocomposites, because they have peculiar characteristics, among them, high aspect ratio, biodegradability and excellent mechanical properties. This work aims to characterize cellulose nanowhiskers from microcrystalline cellulose. Therefore, these materials were characterized by X-ray diffraction (XRD) to assess the degree of crystallinity, infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) to the morphology of nanowhiskers and thermal stability was evaluated by Thermogravimetric Analysis (TGA). (author)

  11. Electrically conductive cellulose composite (United States)

    Evans, Barbara R.; O'Neill, Hugh M.; Woodward, Jonathan


    An electrically conductive cellulose composite includes a cellulose matrix and an electrically conductive carbonaceous material incorporated into the cellulose matrix. The electrical conductivity of the cellulose composite is at least 10 .mu.S/cm at C. The composite can be made by incorporating the electrically conductive carbonaceous material into a culture medium with a cellulose-producing organism, such as Gluconoacetobacter hansenii. The composites can be used to form electrodes, such as for use in membrane electrode assemblies for fuel cells.

  12. Preparation of cellulose nanocrystals from asparagus (Asparagus officinalis L.) and their applications to palm oil/water Pickering emulsion. (United States)

    Wang, Wenhang; Du, Guanhua; Li, Cong; Zhang, Hongjie; Long, Yunduo; Ni, Yonghao


    Nano cellulosic materials as promising emulsion stabilizers have attracted great interest in food industry. In this paper, five different sized cellulose nanocrystals (CNC) samples were prepared from stem of Asparagus officinalis L. using the same sulfuric acid hydrolysis conditions but different times (1.5, 2, 2.5, 3.0, and 3.5h). The sizes of these CNC ranged from 178.2 to 261.8nm, with their crystallinity of 72.4-77.2%. The CNC aqueous dispersions showed a typical shear thinning behavior. In a palm oil/water (30/70, v/v) model solution, stable Pickering emulsions were formed with the addition of CNC, and their sizes are in the range of 1-10μm based on the optical and confocal laser scanning microscopy (CLSM) observation. The CNC sample prepared at 3h hydrolysis time, showed a relative efficient emulsion capacity for palm oil droplets, among these CNCs. Other parameters including the CNC, salt, and casein concentrations on the emulsion stability were studied.

  13. Informatique: tous pour un ... projet

    CERN Multimedia

    Delétraz, F; Requin, J-M


    "Pour des raisons de coût et d'efficacité, les chercheurs font de plus en plus travailler ensemble des ordinateurs éparpillés sur tous les continents. Pour faire avancer la science, tous les moyens et tous les réseaux sont bons" (1 page)

  14. Capillary electrophoretic separation of humic substances using hydroxyethyl cellulose as a buffer additive and its application to characterization of humic substances in a river water sample. (United States)

    Takahashi, Toru; Kawana, Jun; Hoshino, Hitoshi


    We have developed a concise tool for the investigation of the transition of humic substances in environmental water. The separation of water-soluble humic substances was achieved rapidly and effectively by capillary electrophoresis using a polyacrylamide-coated capillary and a phosphate electrophoretic buffer solution (pH 7.0) containing hydroxyethyl cellulose. The separation mechanism was assessed using the ultrafiltration technique. The effect of the complexation of humic substances with metal ions was studied by using the proposed method. When Fe(III) ions or EDTA was added to the sample solution of fulvic acid, a distinct change in the electropherogram pattern based on the conformational change of fulvic acid was observed. The successful application of the proposed method to the characterization of humic substances in a river water sample was also demonstrated.

  15. Procédé de nitruration d'un alliage de titane superélastique pour des applications biomédicales Nitriding process of a superelastic titanium alloy for biomedical applications

    Directory of Open Access Journals (Sweden)

    Bedouin Yvan


    Full Text Available Dans le cadre de ce travail, nous avons mis au point un protocole de nitruration appliqué à un alliage Ti-Nb de type beta, biocompatible et qui présente des propriétés de superélasticité. Cet alliage a ainsi subi un traitement de nitruration en phase gazeuse suivi d'un traitement de recristallisation en phase beta et d'une trempe dans l'eau. Avec ce protocole, l'alliage est nitruré en surface et sa caractéristique superélastique est maintenue. Cet ensemble de propriétés mécaniques peut s'avérer très intéressante pour différentes applications biomédicales. Within the framework of this work, we developed a nitriding process on biocompatible Ti-Nb based beta-type alloy which presents superelastic property. This alloy underwent a nitriding treatment, which was followed by a recrystallization in the beta phase domain before quenching in water. With this protocol, the alloy is thus hardened by the presence of the nitride on the surface while its superelastic characteristic is maintained. This whole of mechanical properties can be very interesting for various biomedical applications.

  16. Cellulose aerogels decorated with multi-walled carbon nanotubes: preparation, characterization, and application for electromagnetic interference shielding

    Directory of Open Access Journals (Sweden)

    Jian LI,Caichao WAN


    Full Text Available Electromagnetic wave pollution has attracted extensive attention because of its ability to affect the operation of electronic machinery and endanger human health. In this work, the environmentally-friendly hybrid aerogels consisting of cellulose and multi-walled carbon nanotubes (MWCNTs were fabricated. The aerogels have a low bulk density of 58.17 mg·cm-3. The incorporation of MWCNTs leads to an improvement in the thermal stability. In addition, the aerogels show a high electromagnetic interference (EMI SEtotal value of 19.4 dB. Meanwhile, the absorption-dominant shielding mechanism helps a lot to reduce secondary radiation, which is beneficial to develop novel eco-friendly EMI shielding materials.

  17. Preparation and Application of Tripeptide-cellulose Ester%三肽纤维素酯的制备及应用研究

    Institute of Scientific and Technical Information of China (English)

    李杨; 朱进科; 李连杰; 蒋登高


    Tripeptide-cellulose ester ( TPC) was synthesized by sequent acyl chlorination, esterification, peptide elongation and amino modification using microcrystalline cellulose as raw material and N-(9-fluorenylmethoxycarbonyl)-L-proline(FMOC-L-Pro-OH), N-(9-fluorenylmethoxycarbonyl)-L-valinamide-L-phenylalanine(FMOC-L-Val-L-Phe-OH), 3,5-dinitrobenzoic acid as derivatization reagents. The experimental results showed that during the synthesis process, esterification, a key step, was performed firstly, and followed by the extension of peptide chain. The effects of various experimental factors on esterification and substitution degree ( DS ) were investigated. The optimal condition was described as that the mass concentration of avicel in LiCl/DMAc 20 g/L, the molar ratio of —C(O)Cl to the hydroxyl content of cellulose 3∶1, reaction temperature 100℃ and reaction time 20 h. By the further peptide elongation and amino modification, the tripeptide-cellulose ester with DS 2. 15 was synthesized. The structure and properties were then characterized by using Fourier transform infrared spectroscopy, elemental analysis, X-ray diffraction and thermogravimetric analysis. The results showed that the modification of peptide by 3,5-dinitrobenzoic acid was successful and the synthesis process was feasible. With the alteration of precipitants, the intramolecular hydrogen bond was different and the obtained derivatives had different characteristics and functionalities. The tripeptide-cellulose ester precipitated in methanol was good enteric-coating material with good shading effect and rapid disintegration, but the physiological toxicity needed further study. The tripeptide-cellulose ester ( using water as the precipitant) could be coated onto silica gel to get a chiral stationary phase, which has a wider application than previous coated-cellulose chiral stationary phase. In addition, the stable chemical resistance of tripeptide-cellulose ester was particularly suitable for the

  18. Cellulose-Based Bio- and Nanocomposites: A Review

    Directory of Open Access Journals (Sweden)

    Susheel Kalia


    Full Text Available Cellulose macro- and nanofibers have gained increasing attention due to the high strength and stiffness, biodegradability and renewability, and their production and application in development of composites. Application of cellulose nanofibers for the development of composites is a relatively new research area. Cellulose macro- and nanofibers can be used as reinforcement in composite materials because of enhanced mechanical, thermal, and biodegradation properties of composites. Cellulose fibers are hydrophilic in nature, so it becomes necessary to increase their surface roughness for the development of composites with enhanced properties. In the present paper, we have reviewed the surface modification of cellulose fibers by various methods. Processing methods, properties, and various applications of nanocellulose and cellulosic composites are also discussed in this paper.

  19. Enhancement of Cellulose Degradation by Cattle Saliva. (United States)

    Seki, Yasutaka; Kikuchi, Yukiko; Kimura, Yoshihiro; Yoshimoto, Ryo; Takahashi, Masatoshi; Aburai, Kenichi; Kanai, Yoshihiro; Ruike, Tatsushi; Iwabata, Kazuki; Sugawara, Fumio; Sakai, Hideki; Abe, Masahiko; Sakaguchi, Kengo


    Saccharification of cellulose is a promising technique for producing alternative source of energy. However, the efficiency of conversion of cellulose into soluble sugar using any currently available methodology is too low for industrial application. Many additives, such as surfactants, have been shown to enhance the efficiency of cellulose-to-sugar conversion. In this study, we have examined first whether cattle saliva, as an additive, would enhance the cellulase-catalyzed hydrolysis of cellulose, and subsequently elucidated the mechanism by which cattle saliva enhanced this conversion. Although cattle saliva, by itself, did not degrade cellulose, it enhanced the cellulase-catalyzed degradation of cellulose. Thus, the amount of reducing sugar produced increased approximately 2.9-fold by the addition of cattle saliva. We also found that non-enzymatic proteins, which were present in cattle saliva, were responsible for causing the enhancement effect. Third, the mechanism of cattle saliva mediated enhancement of cellulase activity was probably similar to that of the canonical surfactants. Cattle saliva is available in large amounts easily and cheaply, and it can be used without further purification. Thus, cattle saliva could be a promising additive for efficient saccharification of cellulose on an industrial scale.

  20. [L'application des radioisotopes a la chromatographie sur colonnes de celluloses substituees-IV L'analyse du mercure et du zinc dans le bismuth]. (United States)

    Muzzarelli, R A; Marcotrigiano, G


    The Chromatographic behaviour of nanogram amounts of bismuth has been studied by radioisotope techniques on cellobiose, cellulose and seven substituted celluloses. All celluloses in ethyl ether adsorb bismuth, provided that it is as nitrate, and that excess of nitric acid is avoided. Bismuth can be eluted with thiocyanate in ether-methanol or with hydrochloric acid in methanol, depending on the retention strength of the various functional groups of celluloses. A very simple method of separation of bismuth from mercury over a wide range of concentration is presented.

  1. The Synthesis of a Novel Cellulose Physical Gel

    Directory of Open Access Journals (Sweden)

    Jiufang Duan


    Full Text Available Cellulose possessing β-cyclodextrin (β-CD was used as a host molecule and cellulose possessing ferrocene (Fc as a guest polymer. Infrared spectra, differential scanning calorimetry (DSC, ultraviolet spectroscopy (UV, and contact angle analysis were used to characterise the material structure and the inclusion behaviour. The results showed that the β-CD-cellulose and the Fc-cellulose can form inclusion complexes. Moreover, ferrocene oxidation, and reduction of state can be adjusted by sodium hypochlorite (NaClO as an oxidant and glutathione (GSH as a reductant. In this study, a physical gel based on β-CD-cellulose/Fc-cellulose was formed under mild conditions in which autonomous healing between cut surfaces occurred after 24 hours. The physical gel can be controlled in the sol-gel transition. The compressive strength of the Fc-cellulose/β-CD-cellulose gel increased with increased cellulose concentration. The host-guest interaction between the side chains of cellulose could strengthen the gel. The cellulose physical gel may eventually be used as a stimulus-responsive, healing material in biomedical applications.

  2. Flexible Photonic Cellulose Nanocrystal Films


    Guidetti, G.; Atifi, S; Vignolini, S; Hamad, WY


    The fabrication of self-assembled cellulose nanocrystal (CNC) films of tunable photonic and mechanical properties using a facile, green approach is demonstrated. The combination of tunable flexibility and iridescence can dramatically expand CNC coating and film barrier capabilities for paints and coating applications, sustainable consumer packaging products, as well as effective templates for photonic and optoelectronic materials and structures. CelluForce Inc., Biotechnology and Biologica...

  3. SUrDyn 2 : Signalétique d’Urgence Dynamique pour les usagers Sourds et Malentendants, vers une mise en application


    Paire-Ficout, Laurence; Alauzet, Aline; Lefebvre-Albaret, François; JOBEZ, Pascal; Boucheix, Jean-Michel; Saby, Laurent


    L’objet du projet SUrDyn 2 est la conception d’un système d’information visuel pour les voyageurs ayant un handicap auditif, dans les contextes de perturbation des réseaux de transport. Il est basé sur deux réalisations antérieures : l’avatar signant Jade destiné à informer les voyageurs en LSF, et un principe de traduction des messages sonores en messages graphiques animés (projet SUrDyn). L’objectif du projet était de coupler ces deux approches de manière optim...

  4. Conception et réalisation d'un convertisseur multicellulaire DC/DC isolé pour application aéronautique


    BRANDELERO, Julio Cezar


    Les travaux de recherche présentés dans ce manuscrit ont été réalisés au Laboratoire Laplace (Laboratoire Plasma et Conversion d’Energie - UMR5213) dans le cadre d'une thèse Cifre avec la société Cirtem et dans le cadre du projet Genome avec pour partenaire Airbus Helicoptère.; The electricity is taking a more important place in the embedded systems. The electricity is a very moldable form of energy, easy to transport and adjustable or transformed with a very low losses. The electrical energy...

  5. Parallelization of applications for networks with homogeneous and heterogeneous processors; Parallelisation d`applications pour des reseaux de processeurs homogenes ou heterogenes

    Energy Technology Data Exchange (ETDEWEB)

    Colombet, L.


    The aim of this thesis is to study and develop efficient methods for parallelization of scientific applications on parallel computers with distributed memory. The first part presents two libraries of PVM (Parallel Virtual Machine) and MPI (Message Passing Interface) communication tools. They allow implementation of programs on most parallel machines, but also on heterogeneous computer networks. This chapter illustrates the problems faced when trying to evaluate performances of networks with heterogeneous processors. To evaluate such performances, the concepts of speed-up and efficiency have been modified and adapted to account for heterogeneity. The second part deals with a study of parallel application libraries such as ScaLAPACK and with the development of communication masking techniques. The general concept is based on communication anticipation, in particular by pipelining message sending operations. Experimental results on Cray T3D and IBM SP1 machines validates the theoretical studies performed on basic algorithms of the libraries discussed above. Two examples of scientific applications are given: the first is a model of young stars for astrophysics and the other is a model of photon trajectories in the Compton effect. (J.S.). 83 refs., 65 figs., 24 tabs.

  6. 浅议建筑工程后浇带施工技术的应用%Application of the Post-pouring Belt Construction Technology in Architecture Engineering

    Institute of Scientific and Technical Information of China (English)


      这些年,新疆经济飞快的增长规模很大程度地促进了整个建筑业的蓬勃发展。建筑业中,后浇带技术无疑是一项相当有用的实际施工手段。本文通过工程实际,对于后浇带技术在新疆实际建筑工程中的实施方法以及具体化的应用进行了简要分析。%In those years, Xinjiang's fast economic growth gr-eatly promotes the rapid development of the construction indu-stry. In the construction industry, post-pouring belt technology is a very useful practical construction method. This paper thro-ugh the engineering practices, briefly analyzes the implemen-tation method of post-pouring belt technology in Xinjiang act-ual construction and the application for concrete.

  7. Une méthode pour estimer l’interception du rayonnement par un couvert bas : application au colza avant montaison

    Directory of Open Access Journals (Sweden)

    Denoroy Pascal


    Full Text Available Dans les modèles de simulation du fonctionnement des cultures, l’interception du rayonnement est une variable cruciale pour la prévision de la productivité en biomasse. D’autre part, la connaissance de l’interception du rayonnement par une culture permet de mieux analyser la réponse à un traitement en autorisant la distinction entre les effets morphogénétique et physiologique du traitement. Par exemple, dans l’étude de la fertilisation azotée du colza [1] on a pu faire la part de l’effet morphogénétique (accroissement de l’indice foliaire, donc de l’interception et de l’amélioration de la conversion photosynthétique du rayonnement absorbé. Dans un cas comme dans l’autre, une estimation correcte de l’interception du rayonnement est essentielle. Très souvent, un formalisme dérivé de la loi de Beer-Lambert est utilisé pour quantifier la part interceptée du rayonnement : PARi = epsiloni PAR (1 et epsiloni = 1 - e- k.IF (2, PAR représentant le rayonnement photosynthétiquement actif incident (exprimé en Joules ou en moles de photons, PARi la part de ce dernier interceptée par le couvert, epsiloni le coefficient (sans dimension d’interception, IF l’indice foliaire et k le coefficient d’extinction du rayonnement. Un formalisme un peu plus complexe doit être utilisé si on veut considérer le rayonnement absorbé [1, 2]. Pour des cultures couvrantes, la sensibilité de ces modèles à la valeur de k est faible pour les IF élevés, c’est pourquoi ces modèles sont souvent utilisés avec succès. Mais aux faibles IF, les modèles sont sensibles à k, d’où l’importance de l’estimation de ce paramètre pour les cultures présentant une longue période de faible couverture du sol, tel le colza peu fertilisé en phase hivernale. De plus, pour les cultures discontinues, c’est-à-dire présentant des zones où le sol n’est pas du tout couvert par la végétation, comme les inter-rangs, on doit

  8. Highly thermostable and pH-stable cellulases from Aspergillus niger NS-2: properties and application for cellulose hydrolysis. (United States)

    Bansal, Namita; Janveja, Chetna; Tewari, Rupinder; Soni, Raman; Soni, Sanjeev Kumar


    Optimization of cultural conditions for enhanced cellulase production by Aspergillus niger NS-2 were studied under solid-state fermentation. Significant increase in yields (CMCase 463.9 ± 20.1 U/g, FPase 101.1 ± 3.5 U/g and β-glucosidase 99 ± 4.0 U/g) were obtained under optimized conditions. Effect of different nutritional parameters was studied to induce the maximum production of cellulase complex. Scale-up studies for enzyme production process were carried out. Characterization studies showed that enzymes produced by A. niger NS-2 were highly temperature- and pH stable. At 50 °C, the half life for CMCase, FPase, β-glucosidase were approximately 240 h. Cellulases from A. niger NS-2 were stable at 35 °C for 24 h over a broader pH range of 3.0-9.0. We examined the feasibility of using steam pretreatment to increase the saccharification yields from various lignocellulosic residues for sugar release which can potentially be used in bioethanol production. Saccharification of pretreated dry potato peels, carrot peels, composite waste mixture, orange peels, onion peels, banana peels, pineapple peels by crude enzyme extract from A. niger NS-2, resulted in very high cellulose conversion efficiencies of 92-98 %.

  9. Preparation of Photocrosslinked Fish Elastin Polypeptide/Microfibrillated Cellulose Composite Gels with Elastic Properties for Biomaterial Applications

    Directory of Open Access Journals (Sweden)

    Shinya Yano


    Full Text Available Photocrosslinked hydrogels reinforced by microfibrillated cellulose (MFC were prepared from a methacrylate-functionalized fish elastin polypeptide and MFC dispersed in dimethylsulfoxide (DMSO. First, a water-soluble elastin peptide with a molecular weight of ca. 500 g/mol from the fish bulbus arteriosus was polymerized by N,N′-dicyclohexylcarbodiimide (DCC, a condensation reagent, and then modified with 2-isocyanatoethyl methacrylate (MOI to yield a photocrosslinkable fish elastin polypeptide. The product was dissolved in DMSO and irradiated with UV light in the presence of a radical photoinitiator. We obtained hydrogels successfully by substitution of DMSO with water. The composite gel with MFC was prepared by UV irradiation of the photocrosslinkable elastin polypeptide mixed with dispersed MFC in DMSO, followed by substitution of DMSO with water. The tensile test of the composite gels revealed that the addition of MFC improved the tensile properties, and the shape of the stress–strain curve of the composite gel became more similar to the typical shape of an elastic material with an increase of MFC content. The rheology measurement showed that the elastic modulus of the composite gel increased with an increase of MFC content. The cell proliferation test on the composite gel showed no toxicity.

  10. Selection of a thermotolerant Kluyveromyces marxianus strain with potential application for cellulosic ethanol production by simultaneous saccharification and fermentation. (United States)

    Castro, Rafael Cunha A; Roberto, Inês C


    The development of technologies for cellulosic ethanol production by simultaneous saccharification and fermentation (SSF) depends on the use of microorganisms with high fermentative rates and thermotolerance. In this study, the ability of five Kluyveromyces marxianus strains to produce ethanol from glucose at 45 °C was investigated. The highest fermentative parameters were observed with K. marxianus NRRL Y-6860, which was then further studied. An initial evaluation of the oxygen supply on ethanol production by the selected yeast and a comparison of SSF process from acid pretreated rice straw between K. marxianus NRRL Y-6860 and Saccharomyces cerevisiae at 30 and 45 °C were carried out. Under the lowest evaluated conditions of aeration and agitation, K. marxianus NRRL Y-6860 produced 21.5 g/L ethanol from 51.3 g/L glucose corresponding to YP/S of 0.44 g/g and QP of 3.63 g/L h. In the SSF experiments, K. marxianus NRRL Y-6860 was more efficient than S. cerevisiae at both evaluated temperatures (30 and 45 °C), attained at the highest temperature an ethanol yield of 0.24 g/g and productivity of 1.44 g/L h.

  11. Poly(3-hydroxybutyrate)-ethyl cellulose based bio-composites with novel characteristics for infection free wound healing application. (United States)

    Iqbal, Hafiz M N; Kyazze, Godfrey; Locke, Ian Charles; Tron, Thierry; Keshavarz, Tajalli


    A series of bio-composites including poly3-hydroxybutyrate [P(3HB)] grafted ethyl cellulose (EC) stated as P(3HB)-EC were successfully synthesised. Furthermore, natural phenols e.g., p-4-hydroxybenzoic acid (HBA) and ferulic acid (FA) were grafted onto the newly developed P(3HB)-EC-based bio-composites under laccase-assisted environment without the use of additional initiators or crosslinking agents. The phenol grafted bio-composites were critically evaluated for their antibacterial and biocompatibility features as well as their degradability in soil. In particular, the results of the antibacterial evaluation for the newly developed bio-composites indicated that 20HBA-g-P(3HB)-EC and 15FA-g-P(3HB)-EC bio-composites exerted strong bactericidal and bacteriostatic activity against Gram(-)E. coli NTCT 10418 as compared to the Gram(+)B. subtilis NCTC 3610. This study shows further that at various phenolic concentrations the newly synthesised bio-composites remained cytocompatible with human keratinocyte-like HaCaT skin cells, as 100% cell viability was recorded, in vitro. As for the degradation, an increase in the degradation rate was recorded during the soil burial analyses over a period of 42 days. These findings suggest that the reported bio-composites have great potential for use in wound healing; covering the affected skin area which may favour tissue repair over shorter periods.

  12. Preparation of photocrosslinked fish elastin polypeptide/microfibrillated cellulose composite gels with elastic properties for biomaterial applications. (United States)

    Yano, Shinya; Mori, Megumi; Teramoto, Naozumi; Iisaka, Makoto; Suzuki, Natsumi; Noto, Masanari; Kaimoto, Yasuko; Kakimoto, Masashi; Yamada, Michio; Shiratsuchi, Eri; Shimasaki, Toshiaki; Shibata, Mitsuhiro


    Photocrosslinked hydrogels reinforced by microfibrillated cellulose (MFC) were prepared from a methacrylate-functionalized fish elastin polypeptide and MFC dispersed in dimethylsulfoxide (DMSO). First, a water-soluble elastin peptide with a molecular weight of ca. 500 g/mol from the fish bulbus arteriosus was polymerized by N,N'-dicyclohexylcarbodiimide (DCC), a condensation reagent, and then modified with 2-isocyanatoethyl methacrylate (MOI) to yield a photocrosslinkable fish elastin polypeptide. The product was dissolved in DMSO and irradiated with UV light in the presence of a radical photoinitiator. We obtained hydrogels successfully by substitution of DMSO with water. The composite gel with MFC was prepared by UV irradiation of the photocrosslinkable elastin polypeptide mixed with dispersed MFC in DMSO, followed by substitution of DMSO with water. The tensile test of the composite gels revealed that the addition of MFC improved the tensile properties, and the shape of the stress-strain curve of the composite gel became more similar to the typical shape of an elastic material with an increase of MFC content. The rheology measurement showed that the elastic modulus of the composite gel increased with an increase of MFC content. The cell proliferation test on the composite gel showed no toxicity.

  13. Isolation of cellulose microfibrils - An enzymatic approach

    Directory of Open Access Journals (Sweden)

    Sain, M.


    Full Text Available Isolation methods and applications of cellulose microfibrils are expanding rapidly due to environmental benefits and specific strength properties, especially in bio-composite science. In this research, we have success-fully developed and explored a novel bio-pretreatment for wood fibre that can substantially improve the microfibril yield, in comparison to current techniques used to isolate cellulose microfibrils. Microfibrils currently are isolated in the laboratory through a combination of high shear refining and cryocrushing. A high energy requirement of these procedures is hampering momentum in the direction of microfibril isolation on a sufficiently large scale to suit potential applications. Any attempt to loosen up the microfibrils by either complete or partial destruction of the hydrogen bonds before the mechanical process would be a step forward in the quest for economical isolation of cellulose microfibrils. Bleached kraft pulp was treated with OS1, a fungus isolated from Dutch Elm trees infected with Dutch elm disease, under different treatment conditions. The percentage yield of cellulose microfibrils, based on their diameter, showed a significant shift towards a lower diameter range after the high shear refining, compared to the yield of cellulose microfibrils from untreated fibres. The overall yield of cellulose microfibrils from the treated fibres did not show any sizeable decrease.

  14. Cellulose Degradation by Cellulose-Clearing and Non-Cellulose-Clearing Brown-Rot Fungi


    Highley, Terry L.


    Cellulose degradation by four cellulose-clearing brown-rot fungi in the Coniophoraceae—Coniophora prasinoides, C. puteana, Leucogyrophana arizonica, and L. olivascens—is compared with that of a non-cellulose-clearing brown-rot fungus, Poria placenta. The cellulose- and the non-cellulose-clearing brown-rot fungi apparently employ similar mechanisms to depolymerize cellulose; most likely a nonenzymatic mechanism is involved.

  15. Growth and characterization of single-crystal CVD diamond for radiation detection applications; Synthese et caracterisation de diamants monocristallins pour applications de detecteur de rayonnements

    Energy Technology Data Exchange (ETDEWEB)

    Tranchant, N


    This work aimed at the study of the synthesis of single crystal diamond using the Microwave enhanced Chemical Vapour Deposition technique (MPCVD). The work enabled the development and optimisation of the growth conditions, from the study of the crystalline quality, of the material purity, and of its electronic properties. The assessment of the transport properties was the most determinant: the use of the time of flight (TOF) technique has enabled the measurement of the carrier mobilities and of their kinetic properties as a function of the temperature. When coupled with collected charge efficiency measurements, the work led to remarkable carrier mobility values obtained in the synthesised crystals (3000 cm{sup 2}.V-1.s{sup -1}). Prepared samples were mounted as detection devices and used successfully in real conditions for the monitoring of ultra-fast pulses, as well as for neutron fluency monitoring, and for medical dosimeters for radiotherapy applications. (author)

  16. Polyimide Cellulose Nanocrystal Composite Aerogels (United States)

    Nguyen, Baochau N.; Meador, Mary Ann; Rowan, Stuart; Cudjoe, Elvis; Sandberg, Anna


    Polyimide (PI) aerogels are highly porous solids having low density, high porosity and low thermal conductivity with good mechanical properties. They are ideal for various applications including use in antenna and insulation such as inflatable decelerators used in entry, decent and landing operations. Recently, attention has been focused on stimuli responsive materials such as cellulose nano crystals (CNCs). CNCs are environmentally friendly, bio-renewable, commonly found in plants and the dermis of sea tunicates, and potentially low cost. This study is to examine the effects of CNC on the polyimide aerogels. The CNC used in this project are extracted from mantle of a sea creature called tunicates. A series of polyimide cellulose nanocrystal composite aerogels has been fabricated having 0-13 wt of CNC. Results will be discussed.

  17. Hydroxypropyl Cellulose Based Non-Volatile Gel Polymer Electrolytes for Dye-Sensitized Solar Cell Applications using 1-methyl-3-propylimidazolium iodide ionic liquid (United States)

    Khanmirzaei, Mohammad Hassan; Ramesh, S.; Ramesh, K.


    Gel polymer electrolytes using imidazolium based ionic liquids have attracted much attention in dye-sensitized solar cell applications. Hydroxypropyl cellulose (HPC), sodium iodide (NaI), 1-methyl-3-propylimidazolium iodide (MPII) as ionic liquid (IL), ethylene carbonate (EC) and propylene carbonate (PC) are used for preparation of non-volatile gel polymer electrolyte (GPE) system (HPC:EC:PC:NaI:MPII) for dye-sensitized solar cell (DSSC) applications. The highest ionic conductivity of 7.37 × 10-3 S cm-1 is achieved after introducing 100% of MPII with respect to the weight of HPC. Temperature-dependent ionic conductivity of gel polymer electrolytes is studied in this work. XRD patterns of gel polymer electrolytes are studied to confirm complexation between HPC polymer, NaI and MPII. Thermal behavior of the GPEs is studied using simultaneous thermal analyzer (STA) and differential scanning calorimetry (DSC). DSSCs are fabricated using gel polymer electrolytes and J-V centeracteristics of fabricated dye sensitized solar cells were analyzed. The gel polymer electrolyte with 100 wt.% of MPII ionic liquid shows the best performance and energy conversion efficiency of 5.79%, with short-circuit current density, open-circuit voltage and fill factor of 13.73 mA cm-2, 610 mV and 69.1%, respectively.

  18. Physicochemical properties of pH-sensitive hydrogels based on hydroxyethyl cellulose-hyaluronic acid and for applications as transdermal delivery systems for skin lesions. (United States)

    Kwon, Soon Sik; Kong, Bong Ju; Park, Soo Nam


    We investigated the physicochemical properties of pH-sensitive hydroxyethyl cellulose (HEC)/hyaluronic acid (HA) complex hydrogels containing isoliquiritigenin (ILTG), and discussed potential applications as transdermal delivery systems for the treatment of skin lesions caused by pH imbalance. HA has skin compatibility and pH functional groups and HEC serves as scaffold to build hydrogels with varied HCE:HA mass ratio. Hydrogels were synthesized via chemical cross-linking, and three-dimensional network structures were characterized via scanning electron microscopy (SEM). The swelling properties and polymer ratios of the hydrogels were investigated at pH values in the range 1-13. HECHA13 (i.e., an HEC:HA mass ratio of 1:3) was found to have optimal rheological and adhesive properties, and was used to investigate the drug release efficiency as a function of pH; the efficiency was greater than 70% at pH 7. Antimicrobial activity assays against Propionibacterium acnes were conducted to take advantage of the pH-sensitive properties of HECHA13. At pH 7, we found that HECHA13, which contained ILTG, inhibited the growth of P. acnes. Furthermore, HECHA13 was found to exhibit excellent permeability into the skin, which penetrated mostly via the hair follicle. These results indicate that this pH-sensitive hydrogel is effective as a transdermal delivery system for antimicrobial therapeutics, with potential applications in the treatment of acne.

  19. Hydroxypropyl Cellulose Based Non-Volatile Gel Polymer Electrolytes for Dye-Sensitized Solar Cell Applications using 1-methyl-3-propylimidazolium iodide ionic liquid. (United States)

    Khanmirzaei, Mohammad Hassan; Ramesh, S; Ramesh, K


    Gel polymer electrolytes using imidazolium based ionic liquids have attracted much attention in dye-sensitized solar cell applications. Hydroxypropyl cellulose (HPC), sodium iodide (NaI), 1-methyl-3-propylimidazolium iodide (MPII) as ionic liquid (IL), ethylene carbonate (EC) and propylene carbonate (PC) are used for preparation of non-volatile gel polymer electrolyte (GPE) system (HPC:EC:PC:NaI:MPII) for dye-sensitized solar cell (DSSC) applications. The highest ionic conductivity of 7.37 × 10(-3) S cm(-1) is achieved after introducing 100% of MPII with respect to the weight of HPC. Temperature-dependent ionic conductivity of gel polymer electrolytes is studied in this work. XRD patterns of gel polymer electrolytes are studied to confirm complexation between HPC polymer, NaI and MPII. Thermal behavior of the GPEs is studied using simultaneous thermal analyzer (STA) and differential scanning calorimetry (DSC). DSSCs are fabricated using gel polymer electrolytes and J-V centeracteristics of fabricated dye sensitized solar cells were analyzed. The gel polymer electrolyte with 100 wt.% of MPII ionic liquid shows the best performance and energy conversion efficiency of 5.79%, with short-circuit current density, open-circuit voltage and fill factor of 13.73 mA cm(-2), 610 mV and 69.1%, respectively.

  20. Etude pour quantifier la part des apports internes dans bâtiment tertiaire BBC. Application au bâtiment de PREDIS


    Chenailler, Hervé; Wurtz, Frédéric; Ploix, Stéphane; Joussellin, Florence; Bontemps, André


    National audience; La conception de bâtiments a longtemps été réduite à la conception de leurs enveloppes, reléguant ainsi la représentation des usages à des courbes d'apports internes gratuits. Or, la recherche de meilleures performances en termes d'efficacité énergétique, qui se traduit par le rapport entre les besoins en énergie non gratuite sur le confort pour les occupants, pose le problème de conception en des termes nouveaux. Il s'agit dès lors de vérifier que l'énergie consommée corre...

  1. Développement d’une application orientée surveillance pour les réseaux de capteurs sous Contiki.


    Saidi, Abdessamad; Mamem, Wafa


    Les progrès technologiques réalisés ces dernières années ont permis le développement de nouveaux types de capteurs dotés de moyens de communication sans fil, peu onéreux et pouvant être configurés pour former des réseaux autonomes. Les limites imposées sont la limitation des capacités de traitement, de stockage et surtout d’énergie. Le rôle d’un capteur est la surveillance de la zone géographique et de l’émission de l’alerte quand il y a un évènement anormal (incendie, tremblement de terre, é...

  2. Two-colour fluorescence fluorimetric analysis for direct quantification of bacteria and its application in monitoring bacterial growth in cellulose degradation systems. (United States)

    Duedu, Kwabena O; French, Christopher E


    Monitoring bacterial growth is an important technique required for many applications such as testing bacteria against compounds (e.g. drugs), evaluating bacterial composition in the environment (e.g. sewage and wastewater or food suspensions) and testing engineered bacteria for various functions (e.g. cellulose degradation). T?=1,^FigItem(1) ^ReloadFigure=Yesraditionally, rapid estimation of bacterial growth is performed using spectrophotometric measurement at 600nm (OD600) but this estimation does not differentiate live and dead cells or other debris. Colony counting enumerates live cells but the process is laborious and not suitable for large numbers of samples. Enumeration of live bacteria by flow cytometry is a more suitable rapid method with the use of dual staining with SYBR I Green nucleic acid gel stain and Propidium Iodide (SYBR-I/PI). Flow cytometry equipment and maintenance costs however are relatively high and this technique is unavailable in many laboratories that may require a rapid method for evaluating bacteria growth. We therefore sought to adapt and evaluate the SYBR-I/PI technique of enumerating live bacterial cells for a cheaper platform, a fluorimeter. The fluorimetry adapted SYBR-I/PI enumeration of bacteria in turbid growth media had direct correlations with OD600 (p>0.001). To enable comparison of fluorescence results across labs and instruments, a fluorescence intensity standard unit, the equivalent fluorescent DNA (EFD) was proposed, evaluated and found useful. The technique was further evaluated for its usefulness in enumerating bacteria in turbid media containing insoluble particles. Reproducible results were obtained which OD600 could not give. An alternative method based on the assessment of total protein using the Pierce Coomassie Plus (Bradford) Assay was also evaluated and compared. In all, the SYBR-I/PI method was found to be the quickest and most reliable. The protocol is potentially useful for high-throughput applications such as

  3. Charging Technology Application of High Power Insensitive Melt-Pour Explosive Based on DNAN%DNAN基高威力钝感熔铸炸药装药工艺应用

    Institute of Scientific and Technical Information of China (English)

    王春光; 魏敏; 刘学柱; 刘永峰


    A charge process of insensitive melt-pour explosive based on 2,4-Dinitroanisole (DNAN) was proposed, due to TNT based melt-pour explosive can't meet the standard of insensitive ammunition. Based on the research results at home and abroad, first, the main advantages of DNAN based explosive was analyzed compared to TNT based explosive. Then, the feasibility, safety, process route and key technology were researched. At last, the application performance of charge technology was tested. The test and application results show that the charge density of trial-produced RBUL-2 high power melt-pour explosive is high. The underwater explosion energy is greater than 2 times TNT equivalent. The warhead explosion load and damaged power is improved, and it has been used to the XX product development.%  针对TNT熔铸炸药不能满足钝感弹药标准的问题,提出一种以2.4-二硝基苯甲醚(DNAN)为熔融介质配制钝感熔铸炸药的装药工艺.基于国内外的研究成果,分析 DNAN 基炸药相比于 TNT 基炸药的主要优点,从可行性、安全性、工艺路线及关键技术出发进行研究,并进行了装药工艺应用性能指标检测试验.试验及应用结果表明:试制的RBUL-2高威力熔铸炸药装药密度高,水下爆炸能量大于2倍TNT当量,提高了战斗部爆炸载荷和毁损威力,并已在××新型产品研制中得到应用.

  4. Amélioration de la fiabilité d'un convertisseur DC/DC boost entrelacé flottant pour des applications pile à combustible et photovoltaiques


    GUILBERT, Damien; NDIAYE, Abdoul; Luberda, Patrice; GAILLARD, Arnaud; Djerdir, Abdesslem


    Dans les systèmes pile à combustible et photovoltaïques, les convertisseurs DC/DC doivent répondre à de nombreuses problématiques en termes de compacité, gain d'élévation, réduction de l'ondulation de courant d'entrée, efficacité énergétique et fiabilité en cas de défauts d'interrupteur de puissance. Dans cet article, un convertisseur DC/DC boost entrelacé flottant a été choisi afin de respecter ces contraintes pour ce type d'application. Malgré la présence de redondance, un défaut d'interrup...

  5. Systèmes de transmission sans fil multi-émetteurs, multi-récepteurs, pour des applications transports. Etude des modèles de canal de propagation




    Les travaux présentés dans ce mémoire portent sur l'utilisation des techniques Mimo pour des applications dans les transports publics (autobus urbains ou métros). Notre travail de recherche s'est tout particulièrement orienté vers la connaissance et la modélisation du canal de propagation Mimo afin de disposer des outils adaptés lors de l'analyse des performances d'une chaine de transmission mimo. Différents types de modèles de canal Mimo sont présentés dans ce mémoire : les modèles détermini...

  6. Effect of Surface Attachment on Synthesis of Bacterial Cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Barbara R [ORNL; O' Neill, Hugh Michael [ORNL


    Gluconacetobacter spp. synthesize a pure form of hydrophilic cellulose that has several industrial specialty applications. Literature reports have concentrated on intensive investigation of static and agitated culture in liquid media containing high nutrient concentrations optimized for maximal cellulose production rates. The behavior of these bacteria on semisolid and solid surfaces has not been specifically addressed. The species Gluconacetobacter hansenii was examined for cellulose synthesis and colony morphology on a range of solid supports, including cotton linters, and on media thickened with agar, methyl cellulose, or gellan. The concentration and chemical structure of the thickening agent were found to be directly related to the formation of contiguous cellulose pellicules. Viability of the bacteria following freezer storage was improved when the bacteria were frozen in their cellulose pellicules.

  7. Hazy Transparent Cellulose Nanopaper (United States)

    Hsieh, Ming-Chun; Koga, Hirotaka; Suganuma, Katsuaki; Nogi, Masaya


    The aim of this study is to clarify light scattering mechanism of hazy transparent cellulose nanopaper. Clear optical transparent nanopaper consists of 3–15 nm wide cellulose nanofibers, which are obtained by the full nanofibrillation of pulp fibers. At the clear transparent nanopaper with 40 μm thickness, their total transmittance are 89.3–91.5% and haze values are 4.9–11.7%. When the pulp fibers are subjected to weak nanofibrillation, hazy transparent nanopapers are obtained. The hazy transparent nanopaper consists of cellulose nanofibers and some microsized cellulose fibers. At the hazy transparent nanopaper with 40 μm thickness, their total transmittance were constant at 88.6–92.1% but their haze value were 27.3–86.7%. Cellulose nanofibers are solid cylinders, whereas the pulp fibers are hollow cylinders. The hollow shape is retained in the microsized cellulose fibers, but they are compressed flat inside the nanopaper. This compressed cavity causes light scattering by the refractive index difference between air and cellulose. As a result, the nanopaper shows a hazy transparent appearance and exhibits a high thermal durability (295–305 °C), and low thermal expansion (8.5–10.6 ppm/K) because of their high density (1.29–1.55 g/cm3) and crystallinity (73–80%).

  8. Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain. (United States)

    Florea, Michael; Hagemann, Henrik; Santosa, Gabriella; Abbott, James; Micklem, Chris N; Spencer-Milnes, Xenia; de Arroyo Garcia, Laura; Paschou, Despoina; Lazenbatt, Christopher; Kong, Deze; Chughtai, Haroon; Jensen, Kirsten; Freemont, Paul S; Kitney, Richard; Reeve, Benjamin; Ellis, Tom


    Bacterial cellulose is a strong and ultrapure form of cellulose produced naturally by several species of the Acetobacteraceae Its high strength, purity, and biocompatibility make it of great interest to materials science; however, precise control of its biosynthesis has remained a challenge for biotechnology. Here we isolate a strain of Komagataeibacter rhaeticus (K. rhaeticus iGEM) that can produce cellulose at high yields, grow in low-nitrogen conditions, and is highly resistant to toxic chemicals. We achieved external control over its bacterial cellulose production through development of a modular genetic toolkit that enables rational reprogramming of the cell. To further its use as an organism for biotechnology, we sequenced its genome and demonstrate genetic circuits that enable functionalization and patterning of heterologous gene expression within the cellulose matrix. This work lays the foundations for using genetic engineering to produce cellulose-based materials, with numerous applications in basic science, materials engineering, and biotechnology.

  9. Methods of detection using a cellulose binding domain fusion product

    Energy Technology Data Exchange (ETDEWEB)

    Shoseyov, Oded (Shimshon, IL); Shpiegl, Itai (North Gallilea, IL); Goldstein, Marc A. (Davis, CA); Doi, Roy H. (Davis, CA)


    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  10. Methods of use of cellulose binding domain proteins (United States)

    Shoseyov, Oded; Shpiegl, Itai; Goldstein, Marc A.; Doi, Roy H.


    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  11. Molecular weights of cellulose nitrates by osmotic pressure measurements

    Directory of Open Access Journals (Sweden)

    dr. V. Subramanyam


    Full Text Available It is well-known that nitro celluloses are employed for a variety of purposes. Broadly  nitrocellulose with relatively high nitrogen content are used in propellant and explosive manufacture nitrocelluloses  with lower nitrogen content find application in celluloid, in the lacquer industry, in cellulose paints, etc.

  12. Matériaux élaborés à partir de fibres enchevêtrées pour une application coeur de structure sandwich = Porous materials made with entangled fibers network for an application as core material for sandwich structures


    Mezeix, Laurent; Bouvet, Christophe; Poquillon, Dominique


    National audience; Des matériaux à architecture poreuse et aléatoire ont été élaborés à partir de fibres de verre ou de carbone enchevêtrées en vue d'une application potentielle comme âme de panneaux sandwich ventilé. Les fibres de carbone ont été choisies pour leurs bonnes propriétés mécanique et les fibres de verre pour leur faible coût. Les contacts entre fibres sont bloqués par collage à la résine époxy. Un moyen d'élaboration original a été développé. Les fibres sont placées dans une enc...

  13. High Performance Regenerated Cellulose Membranes from Trimethylsilyl Cellulose

    KAUST Repository

    Ali, Ola


    Regenerated cellulose (RC) membranes are extensively used in medical and pharmaceutical separation processes due to their biocompatibility, low fouling tendency and solvent resistant properties. They typically possess ultrafiltration and microfiltration separation characteristics, but recently, there have been attempts to widen their pool of applications in nanofiltration processes. In this work, a novel method for preparing high performance composite RC membranes was developed. These membranes reveal molecular weight cut-offs (MWCO) of less than 250 daltons, which possibly put them ahead of all commercial RC membranes and in competition with high performance nanofiltration membranes. The membranes were prepared by acidic hydrolysis of dip-coated trimethylsilyl cellulose (TMSC) films. TMSC, with a degree of silylation (DS) of 2.8, was prepared from microcrystalline cellulose by reaction with hexamethyldisilazane under the homogeneous conditions of LiCl/DMAC solvent system. Effects of parameters, such as coating solution concentration and drying rates, were investigated. It was concluded that higher TMSC concentrations as well as higher solvent evaporation rates favor better MWCOs, mainly due to increase in the selective layer thickness. Successful cross-linking of prepared membranes with glyoxal solutions, in the presence of boric acid as a catalyst, resulted in MWCOs less than 250 daltons. The suitability of this crosslinking reaction for large scale productions was already proven in the manufacturing of durable-press fabrics. For us, the inexpensive raw materials as well as the low reaction times and temperatures were of interest. Moreover, the non-toxic nature of glyoxal is a key advantage in medical and pharmaceutical applications. The membranes prepared in this work are strong candidates for separation of small organic solutes from organic solvents streams in pharmaceutical industries. Their hydrophilicity, compared to typical nanofiltration membranes, offer

  14. Fulton Cellulosic Ethanol Biorefinery

    Energy Technology Data Exchange (ETDEWEB)

    Sumait, Necy [BlueFire Ethanol, Irvine, CA (United States); Cuzens, John [BlueFire Ethanol, Irvine, CA (United States); Klann, Richard [BlueFire Ethanol, Irvine, CA (United States)


    Final report on work performed by BlueFire on the deployment of acid hydrolysis technology to convert cellulosic waste materials into renewable fuels, power and chemicals in a production facility to be located in Fulton, Mississippi.


    Directory of Open Access Journals (Sweden)

    E. K. Gladysheva


    Full Text Available Summary: Bacterial cellulose is an organic material that is synthesized by microorganisms extracellularly. Bacterial cellulose can be used in various industries. Especially, bacterial cellulose has found its application basically in medicine. The production of bacterial cellulose is a complicated and long process. The principal criterion for the process to be successful is bacterial cellulose to be obtained in a higher yield. Russia is lacking an operating facility to produce bacterial cellulose; therefore, research in this art is the hottest topic. This paper reports details on the biosynthesis of bacterial cellulose by the Мedusomyces gisevii microbe and investigates the effect of active acidity level on the bacterial cellulose synthesis. It was found that the synthesis of bacterial cellulose by the symbiosis of Мedusomyces gisevii does not require pH to be artificially maintained. The substrate concentration effect on the bacterial cellulose yield was also examined. The bacterial cellulose synthesis was witnessed to be conjugated with the acetic-acid bacterium growth, and conditions corresponding to a maximal bacterial cells number correspond to a maximum microbial cellulose yield. The maximal bacterial cell number was observed when the glucose concentration in the broth was 20 g/l; as the glucose concentration was increased to 55 g/L, the acetic-acid bacterial cell number diminished in inverse proportion to the substrate concentration, which is likely due to the substrate inhibition. A glucose concentration of 15 g/l and lower is not enough, causing a decrease in the cell number, which is directly proportional to a decline in the substrate concentration. The maximum bacterial cellulose yield (8.7-9.0 % was achieved at an initial glucose concentration of 20-25 g/l in the broth. The conditions providing the maximum bacterial cellulose yield gave an enlarged bacterial cellulose specimen 605 g in weight. The physicochemical properties of the

  16. Le développement des modèles d'habitat pour les salmonidés d'eau courante et leur application à la gestion piscicole

    Directory of Open Access Journals (Sweden)



    Full Text Available Le texte décrit brièvement le développement de HABSCORE, une méthode d'évaluation de l'habitat basée sur une série de modèles statistiques empiriques qui relient l'abondance des salmonidés aux variables d'habitat observées. Des données sur les poissons et l'habitat de 602 sites de référence du Pays de Galles et de Grande-Bretagne ont été utilisées pour développer des modèles de prédiction des populations de salmonidés. Sur ces sites, 130 variables indépendantes ont été relevées à partir desquelles 5 modèles de régression, prédisant la taille des populations salmonicoles, ont été produits. Ces modèles [pour les saumons O+, > O+, les truites O+, > O+ ( O+ (> 20 cm] rendent compte de 28,7 à 46,2 % de la variance totale des densités de population observées dans les données de base. Une partition des variances indique que les modèles prennent en compte 45,1 à 86,7 % de la variation spatiale totale. L'erreur associée aux mesures des variables d'habitat ne représente que moins de 1,1 % de la variance totale dans les 5 modèles. La qualité de ces modèles est brièvement discutée. Les sorties des modèles et les applications potentielles de HABSCORE sont décrites.

  17. Dvorak. Concerto pour violoncelle / Francis Dresel

    Index Scriptorium Estoniae

    Dresel, Francis


    Uuest heliplaadist "Dvorak. Concerto pour violoncelle; Schumann: Concerto pour violoncelle. Orchestre Symphonique d'Estonie, Orchestre Symphonique de la Radio TV d'URSS, Neeme Järvi" Vogue "Archives Sovietiques" 651033 1978

  18. Characterization of Bacterial Cellulose by Gluconacetobacter hansenii CGMCC 3917. (United States)

    Feng, Xianchao; Ullah, Niamat; Wang, Xuejiao; Sun, Xuchun; Li, Chenyi; Bai, Yun; Chen, Lin; Li, Zhixi


    In this study, comprehensive characterization and drying methods on properties of bacterial cellulose were analyzed. Bacterial cellulose was prepared by Gluconacetobacter hansenii CGMCC 3917, which was mutated by high hydrostatic pressure (HHP) treatment. Bacterial cellulose is mainly comprised of cellulose Iα with high crystallinity and purity. High-water holding and absorption capacity were examined by reticulated structure. Thermogravimetric analysis showed high thermal stability. High tensile strength and Young's modulus indicated its mechanical properties. The rheological analysis showed that bacterial cellulose had good consistency and viscosity. These results indicated that bacterial cellulose is a potential food additive and also could be used for a food packaging material. The high textural stability during freeze-thaw cycles makes bacterial cellulose an effective additive for frozen food products. In addition, the properties of bacterial cellulose can be affected by drying methods. Our results suggest that the bacterial cellulose produced from HHP-mutant strain has an effective characterization, which can be used for a wide range of applications in food industry.

  19. Genome sequence and plasmid transformation of the model high-yield bacterial cellulose producer Gluconacetobacter hansenii ATCC 53582 (United States)

    Florea, Michael; Reeve, Benjamin; Abbott, James; Freemont, Paul S.; Ellis, Tom


    Bacterial cellulose is a strong, highly pure form of cellulose that is used in a range of applications in industry, consumer goods and medicine. Gluconacetobacter hansenii ATCC 53582 is one of the highest reported bacterial cellulose producing strains and has been used as a model organism in numerous studies of bacterial cellulose production and studies aiming to increased cellulose productivity. Here we present a high-quality draft genome sequence for G. hansenii ATCC 53582 and find that in addition to the previously described cellulose synthase operon, ATCC 53582 contains two additional cellulose synthase operons and several previously undescribed genes associated with cellulose production. In parallel, we also develop optimized protocols and identify plasmid backbones suitable for transformation of ATCC 53582, albeit with low efficiencies. Together, these results provide important information for further studies into cellulose synthesis and for future studies aiming to genetically engineer G. hansenii ATCC 53582 for increased cellulose productivity.

  20. Dissolution of cellulose in ionic liquid: A review (United States)

    Mohd, N.; Draman, S. F. S.; Salleh, M. S. N.; Yusof, N. B.


    Dissolution of cellulose with ionic liquids (IL) and deep eutectic solvent (DES) lets the comprehensive dissolution of cellulose. Basically, cellulose can be dissolved, in some hydrophilic ionic liquids, such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-allyl-3-methylimidazolium chloride (AMIMCl). Chloride based ionic liquids are suitable solvents for cellulose dissolution. Although the ILs is very useful in fine chemical industry, its application in the pharmaceutical and food industry have been very limited due to issues with toxicity, purity, and high cost. Seeing to these limitations, new green alternative solvent which is DES was used. This green solvents, may be definitely treated as the next-generation reagents for more sustainable industrial development. Thus, this review aims to discuss the dissolution of cellulose either with ionic liquids or DES and its application.

  1. When It Rains, It Pours (United States)

    Mills, Linda


    "It's raining, it's pouring, the old man is snoring!" "The itsy, bitsy spider crawled up the waterspout, down came the rain and washed the spider out. Out came the sun and dried up all the rain, and the itsy, bitsy spider went up the spout again." What do children's nursery rhymes have to do with the school library? The author begins by telling a…

  2. Research Progress of the Preparation and Application of Cellulose/Chitosan Composite Materials%纤维素/壳聚糖复合材料的制备与应用研究进展

    Institute of Scientific and Technical Information of China (English)

    付冉冉; 程博闻; 纪秀杰; 任燕飞; 杨丽云; 汪港; 费鹏飞


    纤维素/壳聚糖复合材料利用纤维素提高了共混材料的力学性能,同时保持了壳聚糖优良的生物相容性和抗菌性,无毒无污染。但是二者分子内和分子间含有大量的氢键,使得在水和常规有机溶剂中很难溶解,限制了复合材料的加工和应用,离子液体的出现为二者的溶解和复合提供了新的思路。综述了纤维素/壳聚糖复合材料的制备方法、制备体系及在工业吸附、生物医疗、食品包装和纺织工业领域的应用,重点介绍了离子液体在此复合材料制备过程中的应用,以为纤维素/壳聚糖复合材料的制备工艺和应用发展提供参考。%The cellulose/chitosan composite can improve the mechanical properties of the blend material due to the cellulose,while maintains the good biocompatibility and antimicrobial properties of chitosan.The composite are non-toxic and pollution-free.However,cellulose and chitosan are difficult to dissolve in water and conventional orga-nic solvents,because of its large proportion of intramolecular and intermolecular hydrogen bonds,which strictly limit its processing and applications.The presence of the ionic liquid provides a new approach for the composite.This re-view aims to summarize the preparation method,preparation system of cellulose/chitosan composite materials and its application in industrial adsorption,biomedical,food packaging and textile industry,with emphasis on the application of ionic liquid in the fabrication of the composite.This paper is expected to provide a reference for the development of fabrication and application of cellulose/chitosan composite.

  3. Synthesis and properties of cellulose functionalized -4, 4'-(propane-2, 2'-diyl) diphenol-SiO2/TiO2 hybrid nanocomposites materials for high performance applications (United States)

    Ramesh, Sivalingam; Kim, Gwang-Hoon; Kim, Heung-Soo; Kim, Jaehwan; Kim, Joo-Hyung


    The general class of organic-inorganic hybrid nanocomposites materials is a fast growing area of research. The significant effort is focused on the ability to control the nanoscale structures via organic functional synthetic approaches with inorganic metal oxides. The properties of nanocomposites material depends on the properties of their individual components but also their morphological and interfacial characteristics. This rapidly expanding field is generating many exciting new materials with novel properties. Mainly, cellulose is considered as the richest renewable materials are presently among the most promising candidates for use in photonics due to their versatility, flexibility, light weight, low cost and ease of modification. Cellulose-metal oxide nanomaterials were developed the technologies to manipulate selfassembly and multifunctionallity, of new technologies to the point where industry can produce advanced and costcompetitive cellulose metal oxide hybrid materials. Therefore, the present study is focused on cellulose-functionalized - 4, 4'-(propane-2, 2'-diyl) diphenol-SiO2/TiO2 hybrid nano-composites materials by in-situ sol-gel process. The chemical and morphological properties of cellulose-functionalized SiO2/TiO2 materials via covalent crosslinking hybrids were characterized by FTIR, XRD, TGA, DSC, SEM, TEM and optical properties.

  4. 玉米秸秆及纤维素高值化应用的研究进展%Research progress on the high-valuable applications of corn stalks and corn stalks cellulose

    Institute of Scientific and Technical Information of China (English)

    王犇; 潘高峰; 黄科林


    文章从玉米产业废弃物玉米秸秆的应用出发,对玉米秸秆从传统方面进行总结,对玉米秸秆纤维素从降解、再生和制备吸附材料三个角度进行高值化应用的综述。%Starting From the applications of corn industry waste corn stalks, This paper summarizes from corn stover traditionally, then the high-value applications of corn stalk cellulose was reviewed from degradation, regeneration and the preparation of the adsorbent material.

  5. Tubes légers à haute résistance pour des applications pétrolières marines Light High Strength Tubes for Offshore Petroeleum Applications

    Directory of Open Access Journals (Sweden)

    Corteville J.


    Full Text Available Les besoins nouveaux en tubes à haute résistance, créés par le développement actuel des gisements pétroliers marins, nous ont conduits à étudier des tubes composites particuliers, élaborés par enrouiement hélicoïdal de rubans d'acier minces à haute résistance enrobés d'une résine époxy polymérisable. Un mode de recouvrement adapté des rubans d'acier confère au composite une bonne étanchéité et des caractéristiques mécaniques élevées. Les propriétés physiques et chimiques de la matrice de résine permettent également d'obtenir une faible densité et une résistance convenable à la corrosion par les fluides pétroliers, l'eau de mer ou les boues de forage. Cette étude préliminaire comporte une analyse théorique simplifiée de ce type de structure composite, puis une partie expérimentale destinée a sélectionner les caractéristiques optimales de l'acier et de la résine et à vérifier les propriétés mécaniques et physico-chimiques obtenues sur ces tubes. Enfin, des exemples d'application en mer profonde destinés à comparer ces tubes composites aux tubes en acier sont présentés. Les premières conclusions de cette étude semblent confirmer l'intérêt de ce type de matériau pour ces applications. The new requirements for high-strength tubes created by thé current development of offshore oilfields led thé authors ta study thé development ot spécial composite tubes formed by thé spiral winding of high-strength thin steel strips coated with a polymerïzable epoxy resin. A particular method of overlapping thé steel strips makes the composite leakproof and leads to good mechanical properties: The physical and chemical properties of thé resin matrix also make for a low specific gravity and suitable résistance to corrosion coused by petroleum fluids, seawater or drilling mud. This preliminary article presents a simplified theoretical analysis of this type of composite structure, followed by an exp


    Directory of Open Access Journals (Sweden)

    Mengjiao Yu,


    Full Text Available Nanocrystalline cellulose (NCC has many potential applications because of its special properties. In this paper, NCC was prepared from bamboo pulp. Bamboo pulp was first pretreated with sodium hydroxide, followed by hydrolysis with sulfuric acid. The concentration of sulfuric acid and the hydrolysis time on the yield of NCC were studied. The results showed that sulfuric acid concentration had larger influence than the hydrolysis time on the yield of NCC. When the temperature was 50oC, the concentration of sulfuric acid was 48wt% and the reaction time was 30 minutes, a high quality of nanocrystalline cellulose was obtained; under these conditions, the length of the nanocrystalline cellulose ranged from 200 nm to 500 nm, the diameter was less than 20 nm, the yield was 15.67wt%, and the crystallinity was 71.98%, which is not only higher than those of cellulose nanocrystals prepared from some non-wood materials, but also higher than bamboo cellulose nanocrystals prepared by other methods.

  7. The effect of the application of protein and cellulose preparations as iodine carriers on stability of thiamine in processed meats

    Directory of Open Access Journals (Sweden)

    Krystyna Szymandera-Buszka


    Full Text Available   Fortification of processed meat with iodised table salt was shown to increase thiamine losses, both during thermal processing and storage. Taking into consideration the fact, as well as the recommendation for reduction of consumption of table salt, alternative iodine carriers need to be searched for. Thus the aim of the study was to determine the effect of soy protein isolate (SPI and wheat fibre (WF as iodine salts’ (potassium iodide and iodate carriers on thiamine stability in selected processed meats (steamed meatballs and burgers. The results were compared to the effect of iodised table salt. The highest thiamine losses were found in the presence of iodised table salt, both in the form of iodide and iodate. The application of iodised WF and SPI significantly limited thiamine losses in the course of steaming. It also made possible to reduce thiamine losses during storage in relation to iodised table salt. It was found that the application of WF and SPI as iodine carriers facilitates increased stability of thiamine in relation to table salt during processing and storage of the meat dishes.  

  8. In Vivo Curdlan/Cellulose Bionanocomposite Synthesis by Genetically Modified Gluconacetobacter xylinus. (United States)

    Fang, Ju; Kawano, Shin; Tajima, Kenji; Kondo, Tetsuo


    Bacterial cellulose pellicle produced by Gluconacetobacter xylinus (G. xylinus) is one of the best biobased materials having a unique supernetwork structure with remarkable physiochemical properties for a wide range of medical and tissue-engineering applications. It is still necessary to modify them to obtain materials suitable for biomedical use with satisfactory mechanical strength, biodegradability, and bioactivity. The aim of this research was to develop a gene-transformation route for the production of bacterial cellulose/Curdlan (β-1,3-glucan) nanocomposites by separate but simultaneous in vivo synthesis of cellulose and Curdlan. Modification of the cellulose-nanofiber-producing system of G. xylinus enabled Curdlan to be synthesized simultaneously with cellulose nanofibers in vivo, resulting in biopreparation of nanocomposites. The obtained Curdlan/cellulose composites were characterized, and their properties were compared with those of normal bacterial cellulose pellicles, indicating that Curdlan mixed with the cellulose nanofibers at the nanoscale without disruption of the nanofiber network structure in the pellicle.


    Directory of Open Access Journals (Sweden)

    Ping Qu


    Full Text Available Polyethersulfone (PES is a common material used for ultrafiltration (UF membranes, which has good chemical resistance, high mechanical properties, and wide temperature tolerances. The hydrophobic property of the PES membrane seriously limits its application. Cellulose fibrils are composed of micro-sized and nano-sized elements, which have high hydrophilicity, strength, and biodegradation. A composite membrane was prepared by the phase inversion induced by an immersion process. The characteristics of the composite membrane were investigated with Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, thermogravimetric analysis (TGA, and atomic force microscopy (AFM. The pure water flux of the composite membrane increased dramatically with the increase of cellulose firbils. Mean pore size and porosity were significantly increased. Both mechanical properties and hydrophilicity were enhanced due to the addition of the cellulose firbils.

  10. Antioxidant films based on cross-linked methyl cellulose and native Chilean berry for food packaging applications. (United States)

    López de Dicastillo, Carol; Rodríguez, Francisco; Guarda, Abel; Galotto, Maria José


    Development of antioxidant and antimicrobial active food packaging materials based on biodegradable polymer and natural plant extracts has numerous advantages as reduction of synthetic additives into the food, reduction of plastic waste, and food protection against microorganisms and oxidation reactions. In this way, active films based on methylcellulose (MC) and maqui (Aristotelia chilensis) berry fruit extract, as a source of antioxidants agents, were studied. On the other hand, due to the high water affinity of MC, this polymer was firstly cross-linked with glutaraldehyde (GA) at different concentrations. The results showed that the addition of GA decreased water solubility, swelling, water vapor permeability of MC films, and the release of antioxidant substances from the active materials increased with the concentration of GA. Natural extract and active cross-linked films were characterized in order to obtain the optimal formulation with the highest antioxidant activity and the best physical properties for latter active food packaging application.

  11. Un imageur radar pour la perception et la caractérisation en milieu naturel


    Rouveure, R.; Faure, P; Monod, M.O.


    National audience; Le processus de perception demeure un point critique pour les applications en environnement extérieur. Le radar hyperfréquence offre dans ce contexte un potentiel important car il permet de résoudre certaines limitations des capteurs optiques (laser, vision). Un capteur de ce type, nommé K2Pi, a été conçu pour des applications de cartographie de l'environnement. Le radar est associé à l'algorithme R SLAM, développé pour dessiner les cartes radar. La carte radar globale est ...

  12. Acid hydrolysis of cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Salazar, H.


    One of the alternatives to increase world production of etha nol is by the hydrolysis of cellulose content of agricultural residues. Studies have been made on the types of hydrolysis: enzimatic and acid. Data obtained from the sulphuric acid hydrolysis of cellulose showed that this process proceed in two steps, with a yield of approximately 95% glucose. Because of increases in cost of alternatives resources, the high demand of the product and the more economic production of ethanol from cellulose materials, it is certain that this technology will be implemented in the future. At the same time further studies on the disposal and reuse of the by-products of this production must be undertaken.

  13. Apports des hautes résolutions spatiales pour l'étude et la cartographie des algues vertes. Application à la grève de St-Michel(22)


    Ruiz, Olivier


    Les apports croissants d'effluents agricoles associés avec des situations hydrodynamiques particulières sont à l'origine de fortes proliférations d'algues vertes du type ulva lactuca (ulves). Lorsque la mer se retire les algues se déposent sur les plages et créent des nuisances pour le tourisme et les professionnels de la mer. Les estimations de biomasse sont alors nécessaires à la fois pour comprendre le phénomène et pour mesurer son ampleur. Pendant la période de forts coefficients de marée...

  14. In-situ polymerized cellulose nanocrystals (CNC)-poly(l-lactide) (PLLA) nanomaterials and applications in nanocomposite processing. (United States)

    Miao, Chuanwei; Hamad, Wadood Y


    CNC-PLLA nanomaterials were synthesized via in-situ ring-opening polymerization of l-lactide in the presence of CNC, resulting in hydrophobic, homogeneous mixture of PLLA-grafted-CNC and free PLLA homopolymer. The free PLLA serves two useful functions: as barrier to further prevent PLLA-g-CNC from forming aggregates, and in creating improved interfacial properties when these nanomaterials are blended with other polymers, hence enhancing their performance. CNC-PLLA nanomaterials can be used for medical or engineering applications as-they-are or by compounding with suitable biopolymers using versatile techniques, such as solution casting, co-extrusion or injection molding, to form hybrid nanocomposites of tunable mechanical properties. When compounded with commercial-grade PLA, the resulting CNC-PLA nanocomposites appear transparent and have tailored (dynamic and static) mechanical and barrier properties, approaching those of poly(ethylene terephthalate), PET. The effect of reaction conditions on the properties of CNC-PLLA nanomaterials have been carefully studied and detailed throughout the paper.

  15. Multifilament cellulose/chitin blend yarn spun from ionic liquids. (United States)

    Mundsinger, Kai; Müller, Alexander; Beyer, Ronald; Hermanutz, Frank; Buchmeiser, Michael R


    Cellulose and chitin, both biopolymers, decompose before reaching their melting points. Therefore, processing these unmodified biopolymers into multifilament yarns is limited to solution chemistry. Especially the processing of chitin into fibers is rather limited to distinctive, often toxic or badly removable solvents often accompanied by chemical de-functionalization to chitosan (degree of acetylation, DA, cellulose/chitin blend fibers using ionic liquids (ILs) as gentle, removable, recyclable and non-deacetylating solvents. Chitin and cellulose are dissolved in ethylmethylimidazolium propionate ([C2mim](+)[OPr](-)) and the obtained one-pot spinning dope is used to produce multifilament fibers by a continuous wet-spinning process. Both the rheology of the corresponding spinning dopes and the structural and physical properties of the obtained fibers have been determined for different biopolymer ratios. With respect to medical or hygienic application, the cellulose/chitin blend fiber show enhanced water retention capacity compared to pure cellulose fibers.

  16. Regenerated cellulose/wool blend enhanced biomimetic hydroxyapatite mineralization. (United States)

    Salama, Ahmed; El-Sakhawy, Mohamed


    The current article investigates the effect of bioactive cellulose/wool blend on calcium phosphate biomimetic mineralization. Regenerated cellulose/wool blend was prepared by dissolution-regeneration of neat cellulose and natural wool in 1-butyl-3-methyl imidazolium chloride [Bmim][Cl], as a solvent for the two polymers. Crystalline hydroxyapatite nanofibers with a uniform size, shape and dimension were formed after immersing the bioactive blend in simulated body fluid. The cytotoxicity of cellulose/wool/hydroxyapatite was studied using animal fibroblast baby hamster kidney cells (BHK-21) and the result displayed good cytocompatability. This research work presents a green processing method for the development of novel cellulose/wool/hydroxyapatite hybrid materials for tissue engineering applications.

  17. Application of Ionic Liquids in the Modification of Starch and Cellulose%离子液体在淀粉和纤维素改性中的应用

    Institute of Scientific and Technical Information of China (English)

    马栋; 谭玉荣; 明建; 赵国华


    近些年来,随着我国改革开放的深入和人民生活水平的提高,人们对食品安全提出了越来越严格的要求.同时由于人们环境意识的日益增强以及绿色化学的兴起,使新型绿色溶剂离子液体广泛应用于食品工业中并且逐渐发挥出巨大的作用,尤其是在淀粉和纤维素改性中的应用.结合国内外相关文献对离子液体在淀粉和纤维素改性中的应用进行总结.在总结的过程中,对淀粉和纤维素在离子液体中改性的发展历程、机理以及相关特点等方面进行论述,探讨了离子液体对淀粉和纤维素改性的影响,并阐述了离子液体在淀粉和纤维素的改性的发展前景和限制因素.%in recent years,with the deepening of reform and opening up and the improvement of people’s living standards,people put forward more and more stringent requirements on food safety.At the same time,due to the increasing environmental awareness and the rise of green chemistry,the new green solvent ionic liquids are widely used in the food industry and gradually play a huge role,especially in the application of modification of starch and cellulose.The paper summarized researches of ionic liquids application in the modification of starch and cellulose combined with related literature at home and abroad.In this paper,we discussed the phylogeny,mechanism and related features of the modification of starch and cellulose in ionic liquids,probed into the influence of ionic liquids on the modification of starch and cellulose,and expounded the prospects and limiting factors of ionic liquids for the development of the modification of starch and cellulose.

  18. Preparation of food grade carboxymethyl cellulose from corn husk agrowaste. (United States)

    Mondal, Md Ibrahim H; Yeasmin, Mst Sarmina; Rahman, Md Saifur


    Alpha-cellulose extracted from corn husks was used as the raw material for the production of food-grade carboxymethyl cellulose (CMC). Preparation of CMC from husk cellulose was carried out by an etherification process, using sodium hydroxide and monochloroacetic acid (MCA), with ethanol as the supporting medium. Characterizations of CMC were carried out by analyzing the spectra of FTIR, XRD patterns and SEM photomicrographs. Degree of substitution (DS) was determined with respect to particle size using chemical methods. Solubility, molecular weight and DS of CMC increased with decreased cellulose particle sizes. Microbiological testing of the prepared CMC was done by the pour plate method. Concentrations of heavy metals such as arsenic, lead, cadmium and mercury in the purified CMC were measured by Atomic Absorption Spectroscopy technique and found to be within the WHO/FAO recommended value. A comparative study with CMC available in the international market was conducted. The purity of the prepared CMC was higher, at 99.99% well above the purity of 99.5% for standard CMC. High purity CMC showed a yield 2.4 g/g with DS 2.41, water holding capacity 5.11 g/g, oil holding capacity 1.59 g/g. The obtained product is well suited for pharmaceutical and food additives.

  19. Application of cellulose anion-exchangers to separation of palladium from platinum or iridium with glycine as complexing agent and atomic-absorption spectrometry for detection. (United States)

    Brajter, K; Słonawska, K


    The use of glycine as complexing agent for chromatographie separation of palladium from platinum, or palladium from iridium, on cellulose anion-exchangers has been investigated and found possible over a wide range of concentration ratios. The method can be used for analysis of Pd-Ir alloys. The nature of the complexes taking part in the ion-exchange has been identified.

  20. Basic Characteristics and Application of Bacterial Cellulose%细菌纤维素的基本特性与其应用

    Institute of Scientific and Technical Information of China (English)

    黄莉; 王英男; 夏秀芳; 丁一; 杨明; 王松


    细菌纤维素是由微生物发酵合成的天然无毒的纳米材料。能够合成细菌纤维素的微生物共有8种,这8种微生物可通过静态发酵和动态发酵两种方式产生细菌纤维素。因为细菌纤维素具有高纯度、高结晶度、精细的网络结构、生物适应性和可降解性等特性,所以在食品及其包装行业、医药保健品业、以及造纸工业中得到了广泛的应用。%Bacterial cellulose is a kind of natural and nontoxic nanomaterials that is synthetized by micro -bial fermentation .There are eight types of micro-organisms that can produce bacterial cellulose , they can pro-duce bacterial cellulose through two ways that the static the fermentation and dynamic fermentation .Bacterial cellulose with high purity , crystallinity , the fine structure of the network , biocompatibility and biodegradability properties, so it has widely used in the food packaging industry , medicine and health products industry , as well as the paper industry .

  1. Isolation and characterization of a ß-glucosidase from a Clavispora strain with potential applications in bioethanol production from cellulosic materials (United States)

    We previously reported on a new yeast strain of Clavispora sp. NRRL Y-50464 that is capable of utilizing cellobiose as sole source of carbon and energy by producing sufficient native ß-glucosidase enzyme activity without further enzyme supplementation for cellulosic ethanol production using simultan...

  2. Cellulose Microfibril Formation by Surface-Tethered Cellulose Synthase Enzymes. (United States)

    Basu, Snehasish; Omadjela, Okako; Gaddes, David; Tadigadapa, Srinivas; Zimmer, Jochen; Catchmark, Jeffrey M


    Cellulose microfibrils are pseudocrystalline arrays of cellulose chains that are synthesized by cellulose synthases. The enzymes are organized into large membrane-embedded complexes in which each enzyme likely synthesizes and secretes a β-(1→4) glucan. The relationship between the organization of the enzymes in these complexes and cellulose crystallization has not been explored. To better understand this relationship, we used atomic force microscopy to visualize cellulose microfibril formation from nickel-film-immobilized bacterial cellulose synthase enzymes (BcsA-Bs), which in standard solution only form amorphous cellulose from monomeric BcsA-B complexes. Fourier transform infrared spectroscopy and X-ray diffraction techniques show that surface-tethered BcsA-Bs synthesize highly crystalline cellulose II in the presence of UDP-Glc, the allosteric activator cyclic-di-GMP, as well as magnesium. The cellulose II cross section/diameter and the crystal size and crystallinity depend on the surface density of tethered enzymes as well as the overall concentration of substrates. Our results provide the correlation between cellulose microfibril formation and the spatial organization of cellulose synthases.

  3. Processing and characterization of natural cellulose fibers/thermoset polymer composites. (United States)

    Thakur, Vijay Kumar; Thakur, Manju Kumari


    Recently natural cellulose fibers from different biorenewable resources have attracted the considerable attraction of research community all around the globe owing to their unique intrinsic properties such as biodegradability, easy availability, environmental friendliness, flexibility, easy processing and impressive physico-mechanical properties. Natural cellulose fibers based materials are finding their applications in a number of fields ranging from automotive to biomedical. Natural cellulose fibers have been frequently used as the reinforcement component in polymers to add the specific properties in the final product. A variety of cellulose fibers based polymer composite materials have been developed using various synthetic strategies. Seeing the immense advantages of cellulose fibers, in this article we discuss the processing of biorenewable natural cellulose fibers; chemical functionalization of cellulose fibers; synthesis of polymer resins; different strategies to prepare cellulose based green polymer composites, and diverse applications of natural cellulose fibers/polymer composite materials. The article provides an in depth analysis and comprehensive knowledge to the beginners in the field of natural cellulose fibers/polymer composites. The prime aim of this review article is to demonstrate the recent development and emerging applications of natural cellulose fibers and their polymer materials.

  4. Molecular Dynamics Simulation of Spontaneous Imbibition in Nanopores and Recovery of Asphaltenic Crude Oils Using Surfactants for EOR Applications Simulations de dynamique moléculaire d’imbibition spontanée dans des nanopores et pour la récupération d’huiles brutes asphalténiques en utilisant des agents tensioactifs pour des applications d’EOR

    Directory of Open Access Journals (Sweden)

    Stukan M.R.


    Full Text Available We present Molecular Dynamics (MD simulations of the imbibition process in nanopores in case of two different mechanisms of the wettability modification. We compare the imbibition of an aqueous surfactant solution into an oil-wet pore driven by surfactant adsorption onto the oil-wet rock surface (coating mechanism and the imbibition of an aqueous surfactants solution driven by surfactants removing the contaminant molecules from the originally water-wet surface (cleaning mechanism. Our results show qualitative difference in the imbibition dynamics in these two cases and indicate that MD simulation is a useful tool to investigate details of the imbibition mechanisms at the pore scale with direct implications for Enhanced Oil Recovery (EOR operations. Nous presentons des simulations de Dynamique Moleculaire (DM du processus d’imbibition dans des nanopores dans le cas de deux mecanismes differents de modification de mouillabilite. Nous comparons l’imbibition d’une solution aqueuse d’agent tensioactif dans un pore mouille d’huile entrainee par une adsorption d’agent tensioactif sur la surface de roche mouillee d’huile (mecanisme de revetement et l’imbibition d’une solution aqueuse d’agent tensioactif entrainee par des agents tensioactifs eliminant les molecules contaminantes de la surface originellement mouillee d’eau (mecanisme de nettoyage. Nos resultats montrent une difference qualitative en matiere de dynamique d’imbibition dans ces deux cas et indiquent que la simulation de DM constitue un outil utile pour etudier les mecanismes d’imbibition a l’echelle des pores avec des implications directes pour des operations de recuperation renforcee d’huile (EOR, Enhanced Oil Recovery.

  5. Calculating cellulose diffraction patterns (United States)

    Although powder diffraction of cellulose is a common experiment, the patterns are not widely understood. The theory is mathematical, there are numerous different crystal forms, and the conventions are not standardized. Experience with IR spectroscopy is not directly transferable. An awful error, tha...

  6. The cellulose resource matrix

    NARCIS (Netherlands)

    Keijsers, E.R.P.; Yilmaz, G.; Dam, van J.E.G.


    The emerging biobased economy is causing shifts from mineral fossil oil based resources towards renewable resources. Because of market mechanisms, current and new industries utilising renewable commodities, will attempt to secure their supply of resources. Cellulose is among these commodities, where

  7. Thin blend films of cellulose and polyacrylonitrile (United States)

    Lu, Rui; Zhang, Xin; Mao, Yimin; Briber, Robert; Wang, Howard

    Cellulose is the most abundant renewable, biocompatible and biodegradable natural polymer. Cellulose exhibits excellent chemical and mechanical stability, which makes it useful for applications such as construction, filtration, bio-scaffolding and packaging. To further expand the potential applications of cellulose materials, their alloying with synthetic polymers has been investigated. In this study, thin films of cotton linter cellulose (CLC) and polyacrylonitrile (PAN) blends with various compositions spanning the entire range from neat CLC to neat PAN were spun cast on silicon wafers from common solutions in dimethyl sulfoxide / ionic liquid mixtures. The morphologies of thin films were characterized using optical microscopy, atomic force microscopy, scanning electron microscopy and X-ray reflectivity. Morphologies of as-cast films are highly sensitive to the film preparation conditions; they vary from featureless smooth films to self-organized ordered nano-patterns to hierarchical structures spanning over multiple length scales from nanometers to tens of microns. By selectively removing the PAN-rich phase, the structures of blend films were studied to gain insights in their very high stability in hot water, acid and salt solutions.

  8. Essays concerning the cellulosic biofuel industry (United States)

    Rosburg, Alicia Sue

    Despite market-based incentives and mandated production, the U.S. cellulosic biofuel industry has been slow to develop. This dissertation explores the economic factors that have limited industry development along with important economic tradeoffs that will be encountered with commercial-scale production. The first essay provides an overview of the policies, potential, and challenges of the biofuel industry, with a focus on cellulosic biofuel. The second essay considers the economics of cellulosic biofuel production. Breakeven models of the local feedstock supply system and biofuel refining process are constructed to develop the Biofuel Breakeven (BioBreak) program, a stochastic, Excel-based program that evaluates the feasibility of local biofuel and biomass markets under various policy and market scenarios. An application of the BioBreak program is presented using expected market conditions for 14 local cellulosic biofuel markets that vary by feedstock and location. The economic costs of biofuel production identified from the BioBreak application are higher than frequently anticipated and raise questions about the potential of cellulosic ethanol as a sustainable and economical substitute for conventional fuels. Program results also are extended using life-cycle analysis to evaluate the cost of reducing GHG emissions by substituting cellulosic ethanol for conventional fuel. The third essay takes a closer look at the economic trade-offs within the biorefinery industry and feedstock production processes. A long-run biomass production through bioenergy conversion cost model is developed that incorporates heterogeneity of biomass suppliers within and between local markets. The model builds on previous literature by treating biomass as a non-commoditized feedstock and relaxes the common assumption of fixed biomass density and price within local markets. An empirical application is provided for switchgrass-based ethanol production within U.S. crop reporting districts

  9. Application Research Progress of Ionic Liquids in Cellulose Chemistry%离子液体在纤维素化学中的应用研究新进展

    Institute of Scientific and Technical Information of China (English)

    张金明; 吕玉霞; 罗楠; 武进; 余坚; 何嘉松; 张军


    As the most abundant natural polymer on the earth, cellulose has many attractive properties such as renewability, biodegradability, biocompatibility, and broad chemical-modifying capacity. Cellulose has been considered as the sustainable raw material of energy and chemical engineering in the future. However, because of the well-developed intra- and intermolecular hydrogen bonding network,cellulose is unmeltable and insoluble in water or conventional organic solvents,which limits its wide utilization. More recently, it is found that certain ionic liquids (ILs) have excellent dissolving capability for cellulose,which provids a new and versatile platform for cellulose processing and derivatization. A series of biopolymer-based materials, biomass energy, platform chemicals, and so on,have been produced with the aid of ILs. Based on about 210 relevant papers published during the past 10 years, this review article highlights recent progress in the field of dissolution, regeneration, derivatization, extraction and conversion of cellulose with ILs. In additon, a perspective on ILs application in cellulose chemistry in the future is briefly discussed. It is hoped that this review work will stimulate research and collaborations that will lead to significant progress in this area.%纤维素是自然界中储量最大的天然高分子,具有可再生、可完全生物降解、生物相容性好等诸多优点,被认为是未来能源、化工的主要原料。由于聚集态结构的特点,天然纤维素不熔融、难溶解,使其应用受到极大限制。近年来,人们发现一定结构的离子液体可以高效地溶解纤维素,这为纤维素的加工与功能化提供了一个崭新和多用途的平台。以离子液体为介质,通过溶解再生和均相衍生化反应可以制得一系列纤维素基高分子材料;通过催化分解等方法,可以得到不同类型的生物质能源以及平台化合物等,从而极大地拓展了纤

  10. Application to Reduce the Steam Consumption of Cellulose Fiber Production%降低丝束生产过程蒸汽消耗应用实践

    Institute of Scientific and Technical Information of China (English)



    To use the 6-sigma tools to analysis the production of cellulose fiber.Optimize the process control to decrease the process variation and to improve the process control.Identify the process special cause and carry the quick fix.Obtain to reduce steam consumption of cellulose fiber.%对丝束生产过程中蒸汽消耗工艺过程进行优化分析,应用六西格玛管理工具分析、控制、减少过程变异,同时关注工艺过程的改善以及识别过程的异因而采取快赢措施,降低丝束生产蒸汽消耗并固化所取得的降耗成果。

  11. Application in the Ethanol Fermentation of Immobilized Yeast Cells in Matrix of Alginate/Magnetic Nanoparticles, on Chitosan-Magnetite Microparticles and Cellulose-coated Magnetic Nanoparticles

    CERN Document Server

    Ivanova, Viara; Hristov, Jordan


    Saccharomyces cerevisiae cells were entrapped in matrix of alginate and magnetic nanoparticles and covalently immobilized on magnetite-containing chitosan and cellulose-coated magnetic nanoparticles. Cellulose-coated magnetic nanoparticles with covalently immobilized thermostable {\\alpha}-amylase and chitosan particles with immobilized glucoamylase were also prepared. The immobilized cells and enzymes were applied in column reactors - 1/for simultaneous corn starch saccharification with the immobilized glucoamylase and production of ethanol with the entrapped or covalently immobilized yeast cells, 2/ for separate ethanol fermentation of the starch hydrolysates with the fixed yeasts. Hydrolysis of corn starch with the immobilized {\\alpha}-amylase and glucoamylase, and separate hydrolysis with the immobilized {\\alpha}-amylase were also examined. In the first reactor the ethanol yield reached approx. 91% of the theoretical; the yield was approx. 86% in the second. The ethanol fermentation was affected by the typ...

  12. Composite edible films based on hydroxypropyl methyl cellulose reinforced with microcrystalline cellulose nanoparticles (United States)

    It has been stated that hydroxypropyl methyl cellulose (HPMC) based films have promising applications in the food industry because of their environmental appeal, low cost, flexibility and transparency. Nevertheless, their mechanical and moisture barrier properties should be improved. The aim of th...

  13. Développement de nouveaux chromophores basés sur le groupement tricyanofurane pour différentes applications en biologie


    Ipuy, Martin


    Tricyanofuran is a strong electro-withdrawing group due to its three conjugated nitrile groups. This electronic characteristic was used to synthetize new fluorescent probes for biological imaging: small molecules owing a strong dipolar behavior that strongly shifts the fluorescence to the red. A first application of this kind of molecules is intracellular pH detection with a phenol moiety conjugated to the tricyanofuran. Thanks to a convenient retro-synthesis, a large family was developed dis...

  14. Contribution à la Modélisation et à la Gestion Thermique des Batteries Lithium-Ion pour des Applications de Véhicules Electriques


    samba, ahmadou


    disponible: Bibliothèque : Université de Caen Normandie. Bibliothèque universitaire Sciences - STAPS; Advanced research on rechargeable Lithium-ion batteries has allowed for large format and high-energy batteries to be largely used in Battery Electric Vehicles (BEVs). For transportation applications, beside limitations of driving range, long charging time is still considered as an important barrier for a wide use of BEVs. The increase of the charging current amplitude may however subject the ...

  15. Estimation de l'état pour la surveillance des systèmes de grandes dimensions. Application aux réseaux électriques


    Thabet, Assem


    This work deals with the state estimation and diagnosis of nonlinear systems with application to power systems. Dynamic modeling is performed using an index 1 property and decoupling techniques. New methods of state estimation, based on Extended Kalman Filter including a sliding window of measurements, are proposed to improve the robustness and accuracy. A new convergence study based on Lyapunov function and conditioning of the observability matrix is proposed to ensure the convergence of the...

  16. Applications of FT-IR spectroscopy to the studies of esterification and crosslinking of cellulose by polycarboxylic acids: Part II. The performance of the crosslinked cotton fabrics (United States)

    Wei, Weishu; Yang, Charles Q.


    Durable press finishing processes are commonly used in the textile industry to produce wrinkle-free cotton fabrics and garments. A durable press finishing agent forms covalent bands with cellulosic hydroxyl groups, thus crosslinking the cellulose molecules. The crosslinking of cellulose increases wrinkle resistance of the treated cotton fabric and reduces fabric mechanical strength. Wrinkle recovery angle (WRA) and tensile strength are the two most important parameters used to evaluate the performance of the crosslinked cotton fabrics and garments. In this study, we investigated the correlation between WRA and tensile strength on one hand, and the amount of crosslinkages formed by the crosslinking agents including dimethyloldihydroxylethyleneurea (DMDHEU) and 1,2,3,4-butanetetracarboxylic acid (BTCA) determined by FT-IR spectroscopy on the other hand. Linear regression curves between the carbonyl band absorbance, and WRA and tensile strength of the treated cotton fabric were developed. The data indicated that FT-IR spectroscopy is a reliable technique for predicting the performance of durable press finished cotton fabrics, therefore can be used as a convenient instrumental method for quality control in the textile and garment industry.

  17. Cellulose Isolation Methodology for NMR Analysis of Cellulose Ultrastructure

    Directory of Open Access Journals (Sweden)

    Art J. Ragauskas


    Full Text Available In order to obtain accurate information about the ultrastructure of cellulose from native biomass by 13C cross polarization magic angle spinning (CP/MAS NMR spectroscopy the cellulose component must be isolated due to overlapping resonances from both lignin and hemicellulose. Typically, cellulose isolation has been achieved via holocellulose pulping to remove lignin followed by an acid hydrolysis procedure to remove the hemicellulose components. Using 13C CP/MAS NMR and non-linear line-fitting of the cellulose C4 region, it was observed that the standard acid hydrolysis procedure caused an apparent increase in crystallinity of ~10% or less on the cellulose isolated from Populus holocellulose. We have examined the effect of the cellulose isolation method, particularly the acid treatment time for hemicellulose removal, on cellulose ultrastructural characteristics by studying these effects on cotton, microcrystalline cellulose (MCC and holocellulose pulped Populus. 13C CP/MAS NMR of MCC indicated that holocellulose pulping and acid hydrolysis has little effect on the crystalline ultrastructural components of cellulose. Although any chemical method to isolate cellulose from native biomass will invariably alter substrate characteristics, especially those related to regions accessible to solvents, we found those changes to be minimal and consistent in samples of typical crystallinity and lignin/hemicellulose content. Based on the rate of the hemicellulose removal, as determined by HPLC-carbohydrate analysis and magnitude of cellulose ultrastructural alteration, the most suitable cellulose isolation methodology utilizes a treatment of 2.5 M HCl at 100 °C for a standard residence time between 1.5 and 4 h. However, for the most accurate crystallinity results this residence time should be determined empirically for a particular sample.

  18. 微晶纤维素在食品工业中的应用研究进展%Research Development of the Application of Microcrystalline Cellulose in Food Industry

    Institute of Scientific and Technical Information of China (English)

    陆红佳; 郑龙辉; 刘雄


    微晶纤维素是由天然纤维素经水解至极限聚合度得到的白色粉末状物质,具有特殊的理化性质,被广泛的应用于化工、医药、食品等行业.文中主要综述了微晶纤维素的理化性质及其在食品工业中的应用,并对其发展前景进行了展望.%Microcrystalline cellulose(MCC) is produced by acid hydrolysis of natural cellulose to a level off degrees of polymerization(LODP).It had wide applications in food, pharmaceuticals, and other industries.This paper mainly reviews its physicochemical properties, its application in food industry, and the prospect of its future development.It also provides theoretical references for researchers for further in-depth study.

  19. Powerful regulatory systems and post-transcriptional gene silencing resist increases in cellulose content in cell walls of barley


    Tan, Hwei-Ting; Shirley, Neil J; Singh, Rohan R; Henderson, Marilyn; Dhugga, Kanwarpal S; Mayo, Gwenda M; Fincher, Geoffrey B.; Burton, Rachel A.


    Background The ability to increase cellulose content and improve the stem strength of cereals could have beneficial applications in stem lodging and producing crops with higher cellulose content for biofuel feedstocks. Here, such potential is explored in the commercially important crop barley through the manipulation of cellulose synthase genes (CesA). Results Barley plants transformed with primary cell wall (PCW) and secondary cell wall (SCW) barley cellulose synthase (HvCesA) cDNAs driven b...

  20. Flammability of Cellulose-Based Fibers and the Effect of Structure of Phosphorus Compounds on Their Flame Retardancy


    Khalifah A. Salmeia; Milijana Jovic; Audrone Ragaisiene; Zaneta Rukuiziene; Rimvydas Milasius; Daiva Mikucioniene; Sabyasachi Gaan


    Cellulose fibers are promoted for use in various textile applications due their sustainable nature. Cellulose-based fibers vary considerably in their mechanical and flammability properties depending on their chemical composition. The chemical composition of a cellulose-based fiber is further dependent on their source (i.e., seed, leaf, cane, fruit, wood, bast, and grass). Being organic in nature, cellulose fibers, and their products thereof, pose considerable fire risk. In this work we have c...

  1. Special MV cable for long stator winding application Transrapid Shanghai; Cable MT special pour enroulements de stator long sur le train Transrapid de Shanghai

    Energy Technology Data Exchange (ETDEWEB)

    Buethe, H.; Le Dren, S.; Steinbrink, D.; Zamzow, P.E. [Nexans Industries GmbH and Co KG (Germany)


    The long stator winding of the Transrapid represents the most innovative high speed MAGLEV technology application for a special rubber MV cable with formerly unequaled mechanical and electrical requirements. For the first time, we are able to provide details about this special MV cable solution, using high quality rubber compounds for conductor insulation and semiconductive outer sheath with gliding coating for the long stator winding of the Transrapid Shanghai propulsion system, and to report that the high demands and specifications of the whole system were fulfilled. (authors)

  2. Méthodologie pour l'identification des systèmes mécaniques articulés : Application au compacteur



    Si l'identification du modèle dynamique des systèmes mécaniques articulés est maintenant un processus bien maîtrisé dans le domaine de la robotique, son application aux engins de chantiers est peu courante. Ce papier présente l'identification du modèle dynamique d'un compacteur en insistant plus sur la méthodologie que sur les équations. La méthodologie comprend trois étapes d'égale importance : planification de mouvements, analyse de chaque mouvement, puis seulement, identification des param...

  3. Enhanced cellulose degradation using cellulase-nanosphere complexes.

    Directory of Open Access Journals (Sweden)

    Craig Blanchette

    Full Text Available Enzyme catalyzed conversion of plant biomass to sugars is an inherently inefficient process, and one of the major factors limiting economical biofuel production. This is due to the physical barrier presented by polymers in plant cell walls, including semi-crystalline cellulose, to soluble enzyme accessibility. In contrast to the enzymes currently used in industry, bacterial cellulosomes organize cellulases and other proteins in a scaffold structure, and are highly efficient in degrading cellulose. To mimic this clustered assembly of enzymes, we conjugated cellulase obtained from Trichoderma viride to polystyrene nanospheres (cellulase:NS and tested the hydrolytic activity of this complex on cellulose substrates from purified and natural sources. Cellulase:NS and free cellulase were equally active on soluble carboxymethyl cellulose (CMC; however, the complexed enzyme displayed a higher affinity in its action on microcrystalline cellulose. Similarly, we found that the cellulase:NS complex was more efficient in degrading natural cellulose structures in the thickened walls of cultured wood cells. These results suggest that nanoparticle-bound enzymes can improve catalytic efficiency on physically intractable substrates. We discuss the potential for further enhancement of cellulose degradation by physically clustering combinations of different glycosyl hydrolase enzymes, and applications for using cellulase:NS complexes in biofuel production.

  4. Characteristics of microcrystalline cellulose and its application in neutral dairy beverage%微晶纤维素特性及其在中性乳饮料中的应用研究

    Institute of Scientific and Technical Information of China (English)

    薛玉清; 舒成亮; 余立意; 杨忻怡; 欧凯; 李言郡; 马海然


    目的:研究胶态微晶纤维素(microcrystalline cellulose, MCC)的流变特性及在中性乳饮料中的应用。方法通过使用流变仪、粘度仪分析研究胶态微晶纤维素的特性,包括触变性、粘度、悬浮能力和对抗热的稳定性。以中性乳饮料为体系,并结合产品离心沉淀率和体系浊度保留率状况,归纳微晶纤维素作为稳定剂使用时的关键影响因素。结果中性乳饮料体系选择微晶纤维素作为稳定剂,产品最终的离心沉淀率大大下降,浊度保留率有所提高。结论微晶纤维素复配卡拉胶、结冷胶对中性乳饮料的稳定性有明显的改善。%Objective To investigate the rheological properties of the gel microcrystalline cellulose (MCC) and its application in neutral dairy beverage.MethodsThe properties including thixotropy, viscosity, suspending ability and thermal stability of microcrystalline cellulose were analyzed using rheometer and viscosity meter. Based on neutral beverage system, the key factors affecting the properties of stabilizer MCC were summarized by combining centrifugal sedimentation rate and system turbidity retention rate.ResultsWith a proper selection of MCC as the stabilizer in neutral dairy beverage system, the centrifugal sedimentation rate of final product greatly reduced with an increased turbidity retention rate.ConclusionMCC combined with carrageenan and gellan gum can improve the stability of the neutral dairy beverage.

  5. Characteristics of microcrystalline cellulose and its application in neutral dairy beverage%微晶纤维素特性及其在中性乳饮料中的应用研究

    Institute of Scientific and Technical Information of China (English)

    薛玉清; 舒成亮; 余立意; 杨忻怡; 欧凯; 李言郡; 马海然


    ABSTRACT:Objective To investigate the rheological properties of the gel microcrystalline cellulose (MCC) and its application in neutral dairy beverage. Methods The properties including thixotropy, viscosity, suspending ability and thermal stability of microcrystalline cellulose were analyzed using rheometer and viscosity meter. Based on neutral beverage system, the key factors affecting the properties of stabilizer MCC were summarized by combining centrifugal sedimentation rate and system turbidity retention rate. Results With a proper selection of MCC as the stabilizer in neutral dairy beverage system, the centrifugal sedimentation rate of final product greatly reduced with an increased turbidity retention rate. Conclusion MCC combined with carrageenan and gellan gum can improve the stability of the neutral dairy beverage.%目的:研究胶态微晶纤维素(microcrystalline cellulose, MCC)的流变特性及在中性乳饮料中的应用。方法通过使用流变仪、粘度仪分析研究胶态微晶纤维素的特性,包括触变性、粘度、悬浮能力和对抗热的稳定性。以中性乳饮料为体系,并结合产品离心沉淀率和体系浊度保留率状况,归纳微晶纤维素作为稳定剂使用时的关键影响因素。结果中性乳饮料体系选择微晶纤维素作为稳定剂,产品最终的离心沉淀率大大下降,浊度保留率有所提高。结论微晶纤维素复配卡拉胶、结冷胶对中性乳饮料的稳定性有明显的改善。

  6. Hybridation des retours d'expérience statistique et cognitif pour l'évaluation des risques : application à la déconstruction des aéronefs


    Villeneuve, Eric


    Les travaux de recherche présentés dans ce document s'inscrivent dans le cadre de la gestion des connaissances appliquée à la déconstruction des avions en fin de vie avec pour objectif l'aide à la décision par l'évaluation des risques. Pour répondre à cet objectif, nous avons développé des mécanismes d'aide à la décision hybridant les retours d'expérience statistique et cognitif pour évaluer les risques sur les zones critiques d'un système. L'approche proposée permet la combinaison des avis d...

  7. Solubility of wood-cellulose in LiCl/DMAC solvent system

    Institute of Scientific and Technical Information of China (English)

    He Jing; Liu Zhu; Li Hua-yang; Wang Guo-hua; Pu Jun-wen


    A LiCl/DMAC solvent system was used to dissolve wood-cellulose with aims to broaden its application in preparing functional materials of modified wood-cellulose. We studied the dissolubility complexion of wood-cellulose in a LiCl/DMAC solvent system, made sure of the important function of LiCl in a cellulose solvent, and further confirmed its dissolution mechanism via the measurement of infrared spectra of soluble products. The study results are as follows: first, LiCl salts, which can form intermediate complexes with cellulose, have played an important role in the LiCl/DMAC solvent system, and their solubility performance is enhanced by reducing the hydrogen bond effect between cellulose molecules; second, the non-aqueous solvent system is a better method for dissolving wood-cellulose in homogenous phase. As found in infrared spectra, the absorption intensity of hydroxyl groups (broad peaks: 3,400 cm-1) decreased greatly in cellulose macromolecules. This is because the degree of association between the hydroxyl groups of cellulose macromolecules is reduced, due to the destruction of the hydrogen bonds. Lastly, wood-cellulose can be dissolved in a LiCl/DMAC solvent thoroughly and efficiently, and can provide a better solvent system for homogeneous synthesis in the preparation of new functional materials via modified wood-cellulose.

  8. Cellulose biogenesis in Dictyostelium discoideum

    Energy Technology Data Exchange (ETDEWEB)

    Blanton, R.L.


    Organisms that synthesize cellulose can be found amongst the bacteria, protistans, fungi, and animals, but it is in plants that the importance of cellulose in function (as the major structural constituent of plant cell walls) and economic use (as wood and fiber) can be best appreciated. The structure of cellulose and its biosynthesis have been the subjects of intense investigation. One of the most important insights gained from these studies is that the synthesis of cellulose by living organisms involves much more than simply the polymerization of glucose into a (1{r_arrow}4)-{beta}-linked polymer. The number of glucoses in a polymer (the degree of polymerization), the crystalline form assumed by the glucan chains when they crystallize to form a microfibril, and the dimensions and orientation of the microfibrils are all subject to cellular control. Instead of cellulose biosynthesis, a more appropriate term might be cellulose biogenesis, to emphasize the involvement of cellular structures and mechanisms in controlling polymerization and directing crystallization and deposition. Dictyostelium discoideum is uniquely suitable for the study of cellulose biogenesis because of its amenability to experimental study and manipulation and the extent of our knowledge of its basic cellular mechanisms (as will be evident from the rest of this volume). In this chapter, I will summarize what is known about cellulose biogenesis in D. discoideum, emphasizing its potential to illuminate our understanding both of D. discoideum development and plant cellulose biogenesis.

  9. Synthetic diamond devices for medical dosimetry applied to radiotherapy; Etude et developpement de dispositifs en diamant synthetique pour la dosimetrie medicale: applications en radiotherapie

    Energy Technology Data Exchange (ETDEWEB)

    Descamps, C


    The aim of this thesis, lead in the framework of an integrated European project entitled M.A.E.S.T.R.O. for ' Methods and Advanced Equipment for Simulation and Treatment in Radio Oncology', was to develop and test synthetic diamond detector in clinical environment for new modalities used in radiotherapy. Diamond is a good candidate for the detection of high energy beams in medical fields. It can be used for passive dosimetry, as thermoluminescent dosimeters or for active dosimetry as ionisation chambers. These two applications are presented here. Concerning the thermoluminescence, several impurities or dopants (boron, phosphorus, and nitrogen) have been incorporated in the diamond films during growth, in order to modify the material dosimetric properties and a detailed study of nitrogen-containing films is proposed. The second part presents the results obtained in active dosimetry. Two guide lines were followed: the measurement set-up optimisation and the material modification. The first dosimetric studies under radiotherapy beams concerning nitrogen-containing polycrystalline diamond as well as high purity single crystal diamond are conclusive. The detectors behaviours are in agreement with the recommendations of the International Atomic Energy Agency (IAEA). (author)

  10. Damage mechanics applied to the seismic behavior of concrete structures; Application de la mecanique de l'endommagement pour le comportement de batiments sous seisme

    Energy Technology Data Exchange (ETDEWEB)

    Ghavamian, Shahrokh; Bonenfant, J. [NECS, F-92300 Sceaux (France); Jason, L. [CEA Saclay, LM2S, SEMT, DM2S, DEN, CEA, F-91191 Gif Sur Yvette (France)


    Complete text of publication follows: The seismic behavior of reinforced concrete structures is generally evaluated through modal spectral approaches, based on linear elastic analysis. In the case of seismic reevaluation of existing structures using traditional methods, since the nonlinear behavior of materials is not taken into account, these techniques often lead to an overestimation of the needs in reinforcement. In this contribution, it is proposed to highlight how including nonlinearity in the mechanical behavior of concrete and steel can improve the seismic evaluation of RC structures. For this purpose, a pushover technique is applied on an office building. Contrary to a classical approach, the progression of the failure mode and the mechanical degradation can be obtained and used to accurately elaborate the best retrofitting strategy. Some improvements of the constitutive laws are nevertheless needed if the use of this type of approaches is to be extended to more complex structures. However, the maturity of most constitutive models is not enough to allow industrial applications

  11. Application of Ionic Liquids in the Pulp and Paper and the Cellulose Industries%离子液体在制浆造纸及纤维素工业的应用

    Institute of Scientific and Technical Information of China (English)

    徐永建; 王皎


    A new type of environmentally friendly green solvents,namely ionic liquids (ILS) has many outstanding properties,making them promisingly employing in many fields.In this paper,the dissolution mechanisms of cellulose in ionic liquids were discussed.Firstly,it was necessary to clarify the relationships between cellulose soubility and ionic liquids structures,cellulose dissolution rate and dissolving conditions,and the dissolving effects on the cellulose.The methods to improve the dissolution rate based on the selection of ionic liquids and the determination of reaction conditions were recommended.The methods to improve the dissolution rate based on the selection of ionic liquids and the determination of reaction conditions were recommended.The,advantages of making fiber derivative materials,such as magnetic material,absorbent,biofilm using ionic liquids as solvent were expounded,and the application of ionic liquids in waste water treatment,deinking,pulping process of pulp and paper making field was prospected.Field was prospected.Finally,the industrialization obstacles and research direction of ionic liquids were provided.%从离子液体结构、溶解反应条件对纤维素溶解的影响以及纤维素溶解前后的差异等方面总结了离子液体对纤维素的溶解能力,阐述了可能的溶解机理。从选取离子液体,确定反应条件的角度提出了提高纤维素溶解率的方法。介绍了以离子液体为溶剂制备磁性材料、吸附剂、生物膜等纤维衍生材料及其应用于相关领域的优势,展望了离子液体在制浆造纸废水处理、脱墨、制浆领域中的应用前景。提出了离子液体工业化存在的问题及离子液体的研究方向。

  12. Research Progress on Cellulose-based Surfactants and the Application in Papermaking Industry%纤维素基表面活性剂的研究进展及在造纸工业中的应用

    Institute of Scientific and Technical Information of China (English)

    贝俊杰; 曹云峰


    The application prospects of cellulose-based surfactants are brightening for its characteristics such as biodegradability and pollution-free. The surfactant possesses amphiphilic structures. The hydrophilic side and hydrophobic side are induced on cellulose skeleton by chemical modifications to prepare the cellulose-based surfactants. A brief review is given regarding the synthesis of ionic and non-ionic cellulose-based surfactants. The long-chain alkyl group and ionic structure or polyester structures are induced into cellulose and its derivatives as hydrophobic and hydrophilic groups by substitution or polymerization. The synthetic surfactants have favorable properties such as surface activities and polymer properties. It can be used as retention aid and pigment dispersants in papermaking industry and is willing to be applied in white water treatment end and waste paper deinking end. To further reduce the cost of the product and develop more efficient and versatile cellulose-based surfactants will be the direction of future research.%纤维素基表面活性剂具有可生物降解、无污染等特性,具有广泛的应用前景。表面活性剂具有双亲结构,纤维素基表面活性剂通过各种化学改性的方法在纤维素骨架上引入亲水端和疏水端,使整个分子具有表面活性。文章综述了离子型和非离子型纤维素基表面活性剂的合成,以纤维素或其衍生物为原料,通过取代、聚合等方法引入长链烷基等作为疏水基团,离子结构或聚醚结构作为亲水基团,合成的表面活性剂表现出良好的表面性能,并具有高分子表面活性剂的特性。纤维素基表面活性剂在造纸工业中的助留剂和涂料分散剂方面有一定的应用,并有望用于白水处理和废纸脱墨工段。而进一步降低产品的成本并开发更高效、功能更多样的纤维素基表面活性剂将成为未来的研究方向。

  13. Structural and physico-mechanical characterization of bio-cellulose produced by a cell-free system. (United States)

    Ullah, Muhammad Wajid; Ul-Islam, Mazhar; Khan, Shaukat; Kim, Yeji; Park, Joong Kon


    This study was aimed to characterize the structural and physico-mechanical properties of bio-cellulose produced through cell-free system. Fourier transform-infrared spectrum illustrated exact matching of structural peaks with microbial cellulose, used as reference. Field-emission scanning electron microscopy revealed that fibrils of bio-cellulose were thicker and more compact than microbial cellulose. The specific positions of peaks in the X-ray diffraction and nuclear magnetic resonance spectra indicated that bio-cellulose possessed cellulose II polymorphic structure. Bio-cellulose presented superior physico-mechanical properties than microbial cellulose. The water holding capacity of bio-cellulose and microbial cellulose were found to be 188.6 ± 5.41 and 167.4 ± 4.32 times their dry-weights, respectively. Tensile strengths and degradation temperature of bio-cellulose were 17.63 MPa and 352 °C, respectively compared to 14.71 MPa and 327 °C of microbial cellulose. Overall, the results indicated successful synthesis and superior properties of bio-cellulose that advocate its effectiveness for various applications.

  14. Models for the Behavior of Offshore Structure Foundations. Part Two: Applications to Structural Design and Quality Assurance Processes Modèles pour le comportement des fondations d'ouvrages types marins. Deuxième partie : applications au calcul d'ouvrage et processus d'assurance qualité

    Directory of Open Access Journals (Sweden)

    Meimon Y.


    structure. Prospects opened up by the research are discussed. La conception des fondations de grands ouvrages est une tâche complexe qui requiert à la fois l'expérience de l'expert et l'utilisation de modèles numériques adéquats pour assurer la sécurité et optimiser les coûts de dimensionnement. En fait, prévoir le comportement d'une fondation nécessite de bien évaluer les effets combinés de la technique de mise en place, de la variabilité spatiale des propriétés mécaniques, de l'incertitude sur les chargements et des techniques de modélisation du comportement mécanique des géomatériaux. Ceci est particulièrement vrai pour les plates-formes marines, qu'elles soient destinées à l'exploration ou à la production du pétrole, dans la mesure où les chargements non-monotones dus à l'environnement marin, souvent très sévère, peuvent avoir des effets très néfastes sur le comportement de ces structures. On présente, en deux parties, la synthèse d'une dizaine d'années d'activités de recherche, menées par une équipe de l'Institut Français du Pétrole (IFP, en collaboration avec plusieurs équipes universitaires et des centres techniques et industriels, pour la mise au point de méthodologies et d'outils adaptés au calcul du comportement des fondations d'ouvrages types marins durant toute la durée de vie de la plate-forme. Cet article concerne la deuxième partie qui est dévolue à l'application des modèles développés au calcul d'ouvrage par la méthode des éléments finis et à l'exposé d'un processus de validation des modèles, étape d'une démarche d'assurance qualité. Méthodes pour le calcul des fondations marines : Le système de programmes FONDOF utilisant la méthode des éléments finis a été développé. Il comprend (fig. 1. 1 des interfaces interactives de mise en données et de dépouillement des résultats ainsi que des modules de calcul, opérationnels comme FONGEO pour les calculs bi et tridimensionnels ou FONDAX pour le

  15. 纤维素基啤酒稳定剂的应用研究%Study on the Application of Cellulose-based Beer Stabilizer

    Institute of Scientific and Technical Information of China (English)

    刘捷; 乔雨轩; 王海明; 祝忠付; 汤克勇


    The fresh wort as the object of study, first the possibility of microcrystalline cellulose ( MCC) and sodium carboxymethyl cellulose ( CMC ) as the stabilizer for beer were discussed by single factor experiment. The factors influencing the stabilizing effect of beer, such as the addition of MCC and CMC, boiling time, were studied by an orthogonal experiment, the strengthened wort turbidity change rate was taken as index before and after the experiment, the optimum process conditions in the processing of beer stability were preliminarily discussed.The results showed that the wort had the optimum stabilization when the experimental condition was dosage of MCC for 200 mg/L, dosage of CMC for 20 mg/L, boiling time of 1.5 h.In the work the mechanism that cellulose based stable system how to improve beer stability was also preliminary analyzed, and the development foreground of the cellulose based as the beer stabilizer was prospected.%以新鲜麦汁为研究对象,首先利用单因素实验分别考察了微晶纤维素和羧甲基纤维素钠用作啤酒稳定剂的可能性。然后用正交实验法研究微晶纤维素添加量、羧甲基纤维素钠添加量和煮沸时间3个因素对稳定效果的影响,以强化实验前后麦汁的浊度变化率为指标,初步探讨了该体系在啤酒稳定处理中的最佳工艺条件。结果表明,在微晶纤维素用量为200 mg/L,羧甲基纤维素钠用量为20 mg/L,煮沸时间为1.5 h时,经处理后麦汁的稳定性最佳。文中还初步分析了纤维素基稳定体系改善啤酒稳定性的机理,并展望了全纤维素基啤酒稳定剂的发展前景。

  16. Electro-mechanical properties of hydrogel composites with micro- and nano-cellulose fillers (United States)

    N, Mohamed Shahid U.; Deshpande, Abhijit P.; Lakshmana Rao, C.


    Stimuli responsive cross-linked hydrogels are of great interest for applications in diverse fields such as sensors and biomaterials. In this study, we investigate polymer composites filled with cellulose fillers. The celluloses used in making the composites were a microcrystalline cellulose of commercial grade and cellulose nano-whiskers obtained through acid hydrolysis of microcrystalline cellulose. The filler concentration was varied and corresponding physical, mechanical and electro-mechanical characterization was carried out. The electro-mechanical properties were determined using a quasi-static method. The fillers not only enhance the mechanical properties of the composite by providing better reinforcement but also provide a quantitative electric potential in the composite. The measurements reveal that the polymer composites prepared from two different cellulose fillers possess a quantitative electric potential which can be utilized in biomedical applications. It is argued that the mechanism behind the quantitative electric potential in the composites is due to streaming potentials arising due to electrical double layer formation.

  17. 6-Deoxy-6-aminoethyleneamino cellulose: synthesis and study of hemocompatibility. (United States)

    Zieger, Michael; Wurlitzer, Michael; Wiegand, Cornelia; Reddersen, Kirsten; Finger, Susanne; Elsner, Peter; Laudeley, Peggy; Liebert, Tim; Heinze, Thomas; Hipler, Uta-Christina


    Hemocompatibility of aqueous solutions of antimicrobial 6-deoxy-6-aminoethyleneamino (AEA) cellulose with different degrees of substitution (DS, 0.54-0.92) was investigated in vitro. The AEA cellulose derivatives were synthesized by tosylation of cellulose and subsequent nucleophilic substitution with 1,2-diaminoethane. The structure was confirmed by elemental analysis as well as by FTIR and NMR spectroscopies. Markers for coagulation (thrombin generation, aPTT, PT, blood clotting, thrombocyte activation) and membrane integrity (hemolysis) were measured in human whole blood, human platelet-rich plasma, human pooled plasma, and erythrocytes suspension. AEA cellulose with a low DS of 0.54 showed the highest hemocompatibility in vitro, suggesting the possibility of biomedical applications.

  18. Sustainable commercial nanocrystalline cellulose manufacturing process with acid recycling. (United States)

    Sarma, Saurabh Jyoti; Ayadi, Mariem; Brar, Satinder Kaur; Berry, Richard


    Nanocrystalline cellulose (NCC) is a biomaterial having potential applications in a wide range of industries. It is industrially produced by concentrated acid hydrolysis of cellulosic materials. In this process, the sulfuric acid rich liquor can be concentrated and reused. However, removal of sugar monomers and oligomers is necessary for such recycling. Membrane and ion exchange technology can be employed to remove sugars; however, such technologies are not efficient in meeting the quality required to recycle the acid solution. As a part of the present study, activated carbon (AC) has been evaluated as an adsorbent for sugar removal from the acidic solution generated during commercial nanocrystalline cellulose manufacturing process. Almost complete removal of sugar can be achieved by this approach. The maximum sugar removal observed during this study was 3.4g/g of AC. Based on this finding, a sustainable method has been proposed for commercial nanocrystalline cellulose manufacturing.

  19. Photooxidation of cellulose nitrate: new insights into degradation mechanisms. (United States)

    Berthumeyrie, Sebastien; Collin, Steeve; Bussiere, Pierre-Olivier; Therias, Sandrine


    Cellulose nitrate (or nitrocellulose) has received considerable interest due to its uses in various applications, such as paints, photographic films and propellants. However, it is considered as one of the primary pollutants in the energetic material industries because it can be degraded to form polluting chemical species. In this work, the UV light degradation of cellulose nitrate films was studied under conditions of artificially accelerated photooxidation. To eliminate the reactivity of nitro groups, the degradation of ethylcellulose was also investigated. Infrared spectroscopy analyses of the chemical modifications caused by the photooxidation of cellulose nitrate films and the resulting formation of volatile products revealed the occurrence of de-nitration and the formation of oxidation photoproducts exhibiting lactone and anhydride functions. The impact of these chemical modifications on the mechanical and thermal properties of cellulose nitrate films includes embrittlement and lower temperatures of ignition when used as a propellant.

  20. Synthesis and properties of fluorescent cotton cellulose labeled with norfloxacin

    Institute of Scientific and Technical Information of China (English)


    To expand the application of cellulose in the field of fluorescence techniques, the cotton cellulose was labeled with norfloxacin (Cell-NF) via a three-step reaction, involving alkali treatment, epoxy activation, and opening of the epoxy rings with norfloxacin molecules. And the coordination complexes of Cell-NF with rare earth ions terbium (Cell-NF-Tb) and europium (Cell-NF-Eu) were obtained. The products were detected by IR, TG, XPS, UV and fluorescence spectra. Results showed that the norfloxacin content of the labeled cellulose was about 6.73 w‰ and the start temperature of decomposition of the Cell-NF was raised by 40°C compared with the stock cotton cellulose. When excited at 340 nm, the Cell-NF, Cell-NF-Tb, and Cell-NF-Eu in the solid state could emit violet (430 nm), green (549 nm) and red (620 nm) light, respectively.

  1. Water-repellent cellulose fiber networks with multifunctional properties. (United States)

    Bayer, Ilker S; Fragouli, Despina; Attanasio, Agnese; Sorce, Barbara; Bertoni, Giovanni; Brescia, Rosaria; Di Corato, Riccardo; Pellegrino, Teresa; Kalyva, Maria; Sabella, Stefania; Pompa, Pier Paolo; Cingolani, Roberto; Athanassiou, Athanassia


    We demonstrate a simple but highly efficient technique to introduce multifunctional properties to cellulose fiber networks by wetting them with ethyl-cyanoacrylate monomer solutions containing various suspended organic submicrometer particles or inorganic nanoparticles. Solutions can be applied on cellulosic surfaces by simple solution casting techniques or by dip coating, both being suitable for large area applications. Immediately after solvent evaporation, ethyl-cyanoacrylate starts cross-linking around cellulose fibers under ambient conditions because of naturally occurring surface hydroxyl groups and adsorbed moisture, encapsulating them with a hydrophobic polymer shell. Furthermore, by dispersing various functional particles in the monomer solutions, hydrophobic ethyl-cyanoacrylate nanocomposites with desired functionalities can be formed around the cellulose fibers. To exhibit the versatility of the method, cellulose sheets were functionalized with different ethyl-cyanoacrylate nanocomposite shells comprising submicrometer wax or polytetrafluoroethylene particles for superhydophobicity, MnFe(2)O(4) nanoparticles for magnetic activity, CdSe/ZnS quantum dots for light emission, and silver nanoparticles for antimicrobial activity. Morphological and functional properties of each system have been studied by scanning and transmission electron microscopy, detailed contact angle measurements, light emission spectra and E. coli bacterial growth measurements. A plethora of potential applications can be envisioned for this technique, such as food and industrial packaging, document protection, catalytic cellulosic membranes, textronic (electrofunctional textiles), electromagnetic devices, authentication of valuable documents, and antimicrobial wound healing products to name a few.

  2. Acetoacetylation of Hydroxyethyl Cellulose

    Institute of Scientific and Technical Information of China (English)

    陈晓锋; 高彦芳; 杜奕; 刘德山


    The acetoacetyl group can be used to improve superabsorbent resins since it is more active than the hydroxyethyl group. The acetoacetyl group can be introduced into the side group of hydroxyethyl cellulose (HEC) to activate HEC using the ester exchange reaction between HEC and ethyl acetoacetate (EAA) to improve HEC grafting. This paper discusses the main factors affecting the reaction, such as the amount of EAA and catalyzer, the reaction temperature, and the reaction time. The acetoacetyl group was successfully introduced into HEC. Within specified ranges, increasing the amount of EAA, the reaction temperature and the reaction time will increase the acetoacetylation.

  3. Cellulose/Gold Nanocrystal Hybrids via an Ionic Liquid/Aqueous Precipitation Route

    Directory of Open Access Journals (Sweden)

    Andreas Taubert


    Full Text Available Injection of a mixture of HAuCl4 and cellulose dissolved in the ionic liquid (IL 1-butyl-3-methylimidazolium chloride [Bmim]Cl into aqueous NaBH4 leads to colloidal gold nanoparticle/cellulose hybrid precipitates. This process is a model example for a very simple and generic approach towards (noble metal/cellulose hybrids, which could find applications in sensing, sterile filtration, or as biomaterials.

  4. Cellulose Synthesis in Agrobacterium tumefaciens

    Energy Technology Data Exchange (ETDEWEB)

    Alan R. White; Ann G. Matthysse


    We have cloned the celC gene and its homologue from E. coli, yhjM, in an expression vector and expressed the both genes in E. coli; we have determined that the YhjM protein is able to complement in vitro cellulose synthesis by extracts of A. tumefaciens celC mutants, we have purified the YhjM protein product and are currently examining its enzymatic activity; we have examined whole cell extracts of CelC and various other cellulose mutants and wild type bacteria for the presence of cellulose oligomers and cellulose; we have examined the ability of extracts of wild type and cellulose mutants including CelC to incorporate UDP-14C-glucose into cellulose and into water-soluble, ethanol-insoluble oligosaccharides; we have made mutants which synthesize greater amounts of cellulose than the wild type; and we have examined the role of cellulose in the formation of biofilms by A. tumefaciens. In addition we have examined the ability of a putative cellulose synthase gene from the tunicate Ciona savignyi to complement an A. tumefaciens celA mutant. The greatest difference between our knowledge of bacterial cellulose synthesis when we started this project and current knowledge is that in 1999 when we wrote the original grant very few bacteria were known to synthesize cellulose and genes involved in this synthesis were sequenced only from Acetobacter species, A. tumefaciens and Rhizobium leguminosarum. Currently many bacteria are known to synthesize cellulose and genes that may be involved have been sequenced from more than 10 species of bacteria. This additional information has raised the possibility of attempting to use genes from one bacterium to complement mutants in another bacterium. This will enable us to examine the question of which genes are responsible for the three dimensional structure of cellulose (since this differs among bacterial species) and also to examine the interactions between the various proteins required for cellulose synthesis. We have carried out one

  5. Reinforced plastics and aerogels by nanocrystalline cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Leung, Alfred C. W.; Lam, Edmond; Chong, Jonathan; Hrapovic, Sabahudin; Luong, John H. T., E-mail: [National Research Council Canada (Canada)


    Nanocrystalline cellulose (NCC), a rigid rod-like nanoscale material, can be produced from cellulosic biomass in powder, liquid, or gel forms by acid and chemical hydrolysis. Owing to its unique and exceptional physicochemical properties, the incorporation of a small amount of NCC into plastic enhances the mechanical strength of the latter by several orders of magnitudes. Carbohydrate-based NCC poses no serious environmental concerns, providing further impetus for the development and applications of this green and renewable biomaterial to fabricate lightweight and biodegradable composites and aerogels. Surface functionalization of NCC remains the main focus of NCC research to tailor its properties for dispersion in hydrophilic or hydrophobic media. It is of uttermost importance to develop tools and protocols for imaging of NCC in a complex matrix and quantify its reinforcement effect.

  6. Reinforced plastics and aerogels by nanocrystalline cellulose (United States)

    Leung, Alfred C. W.; Lam, Edmond; Chong, Jonathan; Hrapovic, Sabahudin; Luong, John H. T.


    Nanocrystalline cellulose (NCC), a rigid rod-like nanoscale material, can be produced from cellulosic biomass in powder, liquid, or gel forms by acid and chemical hydrolysis. Owing to its unique and exceptional physicochemical properties, the incorporation of a small amount of NCC into plastic enhances the mechanical strength of the latter by several orders of magnitudes. Carbohydrate-based NCC poses no serious environmental concerns, providing further impetus for the development and applications of this green and renewable biomaterial to fabricate lightweight and biodegradable composites and aerogels. Surface functionalization of NCC remains the main focus of NCC research to tailor its properties for dispersion in hydrophilic or hydrophobic media. It is of uttermost importance to develop tools and protocols for imaging of NCC in a complex matrix and quantify its reinforcement effect.

  7. Ultrasonic dyeing of cellulose nanofibers. (United States)

    Khatri, Muzamil; Ahmed, Farooq; Jatoi, Abdul Wahab; Mahar, Rasool Bux; Khatri, Zeeshan; Kim, Ick Soo


    Textile dyeing assisted by ultrasonic energy has attained a greater interest in recent years. We report ultrasonic dyeing of nanofibers for the very first time. We chose cellulose nanofibers and dyed with two reactive dyes, CI reactive black 5 and CI reactive red 195. The cellulose nanofibers were prepared by electrospinning of cellulose acetate (CA) followed by deacetylation. The FTIR results confirmed complete conversion of CA into cellulose nanofibers. Dyeing parameters optimized were dyeing temperature, dyeing time and dye concentrations for each class of the dye used. Results revealed that the ultrasonic dyeing produced higher color yield (K/S values) than the conventional dyeing. The color fastness test results depicted good dye fixation. SEM analysis evidenced that ultrasonic energy during dyeing do not affect surface morphology of nanofibers. The results conclude successful dyeing of cellulose nanofibers using ultrasonic energy with better color yield and color fastness results than conventional dyeing.

  8. Démarche pour le choix et/ou la conception d'un moyen de soudage par FSW


    ZIMMER-CHEVRET, Sandra; LANGLOIS, Laurent; LAYE, Julien; Goussain, Jean-Claude; Martin, Patrick; Bigot, Régis


    National audience; Les travaux de recherches présentés concernent l'industrialisation du procédé de soudage par friction malaxage, également appelé Friction Stir Welding (FSW). L'objectif est de fournir des outils aux industriels pour choisir et qualifier une machine pour leurs applications de FSW. Cet article présente une méthodologie pour qualifier et / ou concevoir les moyens de soudage adaptés à une application donnée. La démarche de qualification repose sur l'étude géométrique des pièces...


    Energy Technology Data Exchange (ETDEWEB)

    Leschine, Susan


    This project addressed four major areas of investigation: i) characterization of formation of Cellulomonas uda biofilms on cellulose; ii) characterization of Clostridium phytofermentans biofilm development; colonization of cellulose and its regulation; iii) characterization of Thermobifida fusca biofilm development; colonization of cellulose and its regulation; and iii) description of the architecture of mature C. uda, C. phytofermentans, and T. fusca biofilms. This research is aimed at advancing understanding of biofilm formation and other complex processes involved in the degradation of the abundant cellulosic biomass, and the biology of the microbes involved. Information obtained from these studies is invaluable in the development of practical applications, such as the single-step bioconversion of cellulose-containing residues to fuels and other bioproducts. Our results have clearly shown that cellulose-decomposing microbes rapidly colonize cellulose and form complex structures typical of biofilms. Furthermore, our observations suggest that, as cells multiply on nutritive surfaces during biofilms formation, dramatic cell morphological changes occur. We speculated that morphological changes, which involve a transition from rod-shaped cells to more rounded forms, might be more apparent in a filamentous microbe. In order to test this hypothesis, we included in our research a study of biofilm formation by T. fusca, a thermophilic cellulolytic actinomycete commonly found in compost. The cellulase system of T. fusca has been extensively detailed through the work of David Wilson and colleagues at Cornell, and also, genome sequence of a T. fusca strain has been determine by the DOE Joint Genome Institute. Thus, T. fusca is an excellent subject for studies of biofilm development and its potential impacts on cellulose degradation. We also completed a study of the chitinase system of C. uda. This work provided essential background information for understanding how C. uda

  10. The World's Largest Steel Casting Poured Successfully

    Institute of Scientific and Technical Information of China (English)


    @@ The world's largest steel casting -- the upper beam (or the top head) for free forging oil hydraulic press with a 18,000-ton force capacity, was poured successfully by CITIC Heavy Machinery Co., Ltd. (CITICHM) on May 22, 2008. This head piece is 11.95 meters long, 3.8 meters wide, 4.59 meters high and about 520 tons in gross weight. Pouring is the most important and critical step during its manufacturing process. The production of this huge casting requires about 830 tons of refined molten steel from 10 smelting furnaces and pouring with six ladles into the mold cavity at one time, which made it currently the world's largest steel casting poured and the most one-time molten steel organized.

  11. Modification of a cellulose derived for your application on enzyme immobilization;Modificacao de um derivado celulosico para sua aplicacao na imobilizacao de enzimas

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Elaine S.; Rodriguez, Ruben J.S.; Lamonica, Alano C., E-mail: ecarvalho@uenf.b [Universidade Estadual do Norte Fluminense Darcy Ribeiro (LAMAV/UENF), Campos dos Goytacazes, RJ (Brazil). Lab. de Materiais Avancados; Tavares, Maria Ines B. [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Profa. Eloisa Mano


    The chemical modification of (acrylamidomethyl) cellulose acetate propionate (AMCAP) was done through the technique of grafting via radical using acrylic acid as modifier, with the objective to make the polymer more hydrophilic. The structural characterization of AMCAP and modified AMCAP-H{sub 2}O{sub 2} was analysed by using the technique of {sup 13}C-nuclear magnetic resonance (NMR-{sup 13}C). By the techniques differential scanning calorimetry analysis (DSC) and thermogravimetric analysis (TGA), the thermal properties was characterized and the hydrophobic / hydrophilic character was determined by measurements of the contact angle. The results show that occurred the change intended with the introduction of acrylic acid in the side chain of the polymer, increasing the hydrophilic character on the AMCAP. (author)

  12. Functionalization of Cellulose Nanocrystals in Choline Lactate Ionic Liquid

    Directory of Open Access Journals (Sweden)

    Sarah Montes


    Full Text Available Cellulose nanocrystals (CNCs are valuable nanomaterials obtained from renewable resources. Their properties make them suitable for a wide range of applications, including polymer reinforcement. However, due to their highly hydrophilic character, it is necessary to modify their surface with non-polar functional groups before their incorporation into a hydrophobic polymer matrix. In this work, cellulose nanocrystals were modified using a silane coupling agent and choline lactate, an ionic liquid derived from renewable resources, as a reaction medium. Modified cellulose nanocrystals were characterized by infrared spectroscopy, showing new peaks associated to the modification performed. X-ray diffraction was used to analyze the crystalline structure of functionalized cellulose nanocrystals and to optimize the amount of silane for functionalization. Poly(lactic acid (PLA nanocomposites containing 1 wt % of functionalized cellulose nanocrystals were prepared. They were characterized by field-emission scanning electron microscopy (FE-SEM and mechanical tests. The use of choline lactate as reaction media has been shown to be an alternative method for the dispersion and silanization of the cellulose nanocrystals without the addition of an external catalyst.

  13. Cellulose fermentation by nitrogen-fixing anaerobic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Canale-Parola, E.


    In anaerobic natural environments cellulose is degraded to methane, carbon dioxide and other products by the combined activities of many diverse microorganisms. We are simulating processes occurring in natural environments by constructing biologically-defined, stable, heterogeneous bacterial communities (consortia) that we use as in vitro systems for quantitative studies of cellulose degradation under conditions of combined nitrogen deprivation. These studies include the investigation of (i) metabolic interactions among members of cellulose-degrading microbial populations, and (ii) processes that regulate the activity or biosynthesis of cellulolytic enzymes. In addition, we are studying the sensory mechanisms that, in natural environments, may enable motile cellulolytic bacteria to migrate toward cellulose. This part of our work includes biochemical characterization of the cellobiose chemoreceptor of cellulolytic bacteria. Finally, an important aspect of our research is the investigation of the mechanisms by which multienzyme complexes of anaerobic bacteria catalyze the depolymerization of crystalline cellulose and of other plant cell wall polysacchaddes. The research will provide fundamental information on the physiology and ecology of cellulose-fermenting, N{sub 2}-fixing bacteria, and on the intricate processes involved in C and N cycling in anaerobic environments. Furthermore, the information will be valuable for the development of practical applications, such as the conversion of plant biomass (e.g., agricultural, forestry and municipal wastes) to automotive fuels such as ethanol.

  14. Imidazolium-based ionic liquids for cellulose pretreatment: recent progresses and future perspectives. (United States)

    Cao, Yujin; Zhang, Rubing; Cheng, Tao; Guo, Jing; Xian, Mo; Liu, Huizhou


    As the most abundant biomass in nature, cellulose is considered to be an excellent feedstock to produce renewable fuels and fine chemicals. Due to its hydrogen-bonded supramolecular structure, cellulose is hardly soluble in water and most conventional organic solvents, limiting its further applications. The emergence of ionic liquids (ILs) provides an environmentally friendly, biodegradable solvent system to dissolve cellulose. This review summarizes recent advances concerning imidazolium-based ILs for cellulose pretreatment. The structure of cations and anions which has an influence on the solubility is emphasized. Methods to assist cellulose pretreatment with ILs are discussed. The state of art of the recovery, regeneration, and reuse aspects of ILs is also presented in this work. The current challenges and development directions of cellulose dissolution in ILs are put forward. Although further studies are still much required, commercialization of IL-based processes has made great progress in recent years.

  15. 21 CFR 172.868 - Ethyl cellulose. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ethyl cellulose. 172.868 Section 172.868 Food and... Multipurpose Additives § 172.868 Ethyl cellulose. The food additive ethyl cellulose may be safely used in food in accordance with the following prescribed conditions: (a) The food additive is a cellulose...

  16. 21 CFR 573.420 - Ethyl cellulose. (United States)


    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Ethyl cellulose. 573.420 Section 573.420 Food and... Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in accordance with the following prescribed conditions: (a) The food additive is a cellulose ether...

  17. Cellulose Nanomaterials in Water Treatment Technologies


    Carpenter, Alexis Wells; de Lannoy, Charles François; Mark R. Wiesner


    Cellulose nanomaterials are naturally occurring with unique structural, mechanical and optical properties. While the paper and packaging, automotive, personal care, construction, and textiles industries have recognized cellulose nanomaterials’ potential, we suggest cellulose nanomaterials have great untapped potential in water treatment technologies. In this review, we gather evidence of cellulose nanomaterials’ beneficial role in environmental remediation and membranes for water filtration, ...

  18. Capteur utilisant un guide d'onde électro-optique pour la mesure du champ magnétique RF sub-pT par voie optique : application à l'IRM endoluminale


    Saniour, Isabelle; Aydé, Reina; Perrier, Anne-Laure; Gaborit, Gwenaël; Duvillaret, Lionel; Dahdah, Jean; Sablong, Raphaël; Beuf, Olivier


    International audience; Un capteur endoluminal haute sensibilité à liaison optique dédié à détecter le champ magnétique pour l'Imagerie par Résonance Magnétique (IRM) est en construction. Ce capteur permettra à la fois de transmettre optiquement le signal radiofréquence (RF) détecté et d'être découplé optiquement pour améliorer l'uniformité du rapport signal sur bruit des images de RM. Ces deux fonctions sont séparées dans ce papier. Un guide d'onde Ti:LiNbO 3 électro-optique (EO) est associé...

  19. Drying of Pigment-Cellulose Nanofibril Substrates

    Directory of Open Access Journals (Sweden)

    Oleg Timofeev


    Full Text Available A new substrate containing cellulose nanofibrils and inorganic pigment particles has been developed for printed electronics applications. The studied composite structure contains 80% fillers and is mechanically stable and flexible. Before drying, the solids content can be as low as 20% due to the high water binding capacity of the cellulose nanofibrils. We have studied several drying methods and their effects on the substrate properties. The aim is to achieve a tight, smooth surface keeping the drying efficiency simultaneously at a high level. The methods studied include: (1 drying on a hot metal surface; (2 air impingement drying; and (3 hot pressing. Somewhat surprisingly, drying rates measured for the pigment-cellulose nanofibril substrates were quite similar to those for the reference board sheets. Very high dewatering rates were observed for the hot pressing at high moisture contents. The drying method had significant effects on the final substrate properties, especially on short-range surface smoothness. The best smoothness was obtained with a combination of impingement and contact drying. The mechanical properties of the sheets were also affected by the drying method and associated temperature.

  20. Elaboration et caractérisation d'alliages de type Ti-Nb-X (X = O, N pour des applications biomédicales Synthesis and characterisation of Ti-Nb-X (X = O, N alloys for biomedical application

    Directory of Open Access Journals (Sweden)

    Ramarolahy A.


    Full Text Available Dans cette étude, trois alliages de titane β-métastables de composition Ti-27Nb, Ti-24Nb-0.5N et Ti-24Nb-0.5O ont été élaborés par fusion. Ces trois alliages présentent des propriétés superélastiques lors des essais de traction. Des essais de traction in-situ sous rayonnement synchrotron nous ont permis de monter que cette superélasticité est due à une transformation martensitique réversible β → α” bien connue pour deux alliages alors que celui contenant de l'oxygène présente un comportement moins conventionnel. Les températures caractéristiques (MS, MF de la transformation martensitique β (austénite vers α” (martensite et celles (AS, AF de la transformation inverse α” vers β ont aussi été déterminées par des essais mécaniques dynamiques. Ces températures caractéristiques augmentent linéairement avec la contrainte externe et cette augmentation suit la relation de Clausius Clapeyron. Ti-Nb based alloys are well known to their good mechanical properties, shape memory effect, superelasticity, as well as good biocompatibility. Our study is focused on the improvement of their mechanical properties by adding alloying element such as oxygen or nitrogen. Superelasticity was drastically improved by addition of a few amount (0.5 at % of oxygen or nitrogen. Martensitic transformation between the β parent phase (austenite and α” product phase (martensite, responsible for the superelastic property, has been extensively studied by Dynamic Mechanical Analysis (DMA and in-situ tensile test under X-ray synchrotron diffraction.

  1. Development of New Type of Regenerated Protein and Cellulose Composite Fiber and Its Application%新型蛋白质复合再生纤维素纤维的开发应用

    Institute of Scientific and Technical Information of China (English)

    马君志; 李昌垒; 孙东升; 李文斌; 李高雯


    The paper introduces the preparation technology, characteristics and application of new type of re-generated protein and cellulose composite fiber, and also analyzes the morphological structure of this fiber, the cross section of which appears irregular flat and hollow structure with smooth edges compared to the common viscose fiber. And infrared spectrum shows that the new type of regenerated protein and cellulose composite fiber is com-posed of cellulose fiber and protein fiber; X-ray scattering analysis shows that the orientation and crystallization of this composite fiber decrease with the increasing of protein ultrafine powders. Meanwhile, the protein content are tested and compared by using Kjeldahl and sodium hypochlorite methods, the results show that the losses of protein ultrafine powders increase with the increasing of the amount of that, but the protein content of fiber has remained comparatively high, which can guarantee good properties.%介绍了新型蛋白质复合再生纤维素纤维的制备技术、性能特点及开发应用。重点对该纤维的形态结构及性能进行了分析,得出其纤维截面形态结构与普通黏胶纤维不同,呈现不规则扁平中空结构,外缘圆滑。红外光谱图表明蛋白质复合再生纤维素纤维是由纤维素纤维和蛋白质纤维复合而成;X射线衍射分析表明,复合纤维随蛋白质超细粉体添加量的增加,取向度和结晶度下降。采用凯氏定氮法、次氯酸钠法对蛋白质复合再生纤维素纤维进行蛋白质含量的测定和对比分析,结果表明:虽然在制备过程中蛋白超细粉体随着添加量的增加,流失量增加,但是流失后纤维中蛋白质含量仍然相对较高,保证了纤维的性能特征。

  2. Kits and methods of detection using cellulose binding domain fusion proteins

    Energy Technology Data Exchange (ETDEWEB)

    Shoseyov, Oded (Karmey Yosef, IL)


    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  3. Hydrogen peroxide production from fibrous pectic cellulose analogs and effect on dermal fibroblasts (United States)

    Naturally derived products with folklore remedies have in recent years been reconsidered for their benefit to wound healing i.e., honey’s application to chronic wound dressing products. Similarly, we have undertaken an evaluation of Fibrous pectin-cellulose (FPC) (cellulose blended with primary cel...

  4. Physical and mechanical testing of essential oil-embedded cellulose ester films (United States)

    Polymer films made from cellulose esters are useful for embedding plant essential oils, either for food packaging or air freshener applications. Studies and testing were done on the physical and mechanical properties of cellulose ester-based films incorporating essential oils (EO) from lemongrass (C...

  5. Preparation and characterization of transparent PMMA-cellulose-based nanocomposites. (United States)

    Kiziltas, Esra Erbas; Kiziltas, Alper; Bollin, Shannon C; Gardner, Douglas J


    Nanocomposites of polymethylmethacrylate (PMMA) and cellulose were made by a solution casting method using acetone as the solvent. The nanofiber networks were prepared using three different types of cellulose nanofibers: (i) nanofibrillated cellulose (NFC), (ii) cellulose nanocrystals (CNC) and (iii) bacterial cellulose from nata de coca (NDC). The loading of cellulose nanofibrils in the PMMA varied between 0.25 and 0.5 wt%. The mechanical properties of the composites were evaluated using a dynamic mechanical thermal analyzer (DMTA). The flexural modulus of the nanocomposites reinforced with NDC at the 0.5 wt% loading level increased 23% compared to that of pure PMMA. The NFC composite also exhibited a slightly increased flexural strength around 60 MPa while PMMA had a flexural strength of 57 MPa. The addition of NDC increased the storage modulus (11%) compared to neat PMMA at room temperature while the storage modulus of PPMA/CNC nanocomposite containing 0.25 and 0.5 wt% cellulose increased about 46% and 260% to that of the pure PMMA at the glass transition temperature, respectively. Thermogravimetric analysis (TGA) indicated that there was no significant change in thermal stability of the composites. The UV-vis transmittance of the CNF nanocomposites decreased by 9% and 27% with the addition of 0.25 wt% CNC and NDC, respectively. This work is intended to spur research and development activity for application of CNF reinforced PMMA nanocomposites in applications such as: packaging, flexible screens, optically transparent films and light-weight transparent materials for ballistic protection.

  6. Cellulose nanowhiskers extracted from TEMPO-oxidized jute fibers. (United States)

    Cao, Xinwang; Ding, Bin; Yu, Jianyong; Al-Deyab, Salem S


    Cellulose nanowhiskers is a kind of renewable and biocompatible nanomaterials evoke much interest because of its versatility in various applications. Here, for the first time, a novel controllable fabrication of cellulose nanowhiskers from jute fibers with a high yield (over 80%) via a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO system selective oxidization combined with mechanical homogenization is reported. The versatile jute cellulose nanowhiskers with ultrathin diameters (3-10 nm) and high crystallinity (69.72%), contains C6 carboxylate groups converted from C6 primary hydroxyls, which would be particularly useful for applications in the nanocomposites as reinforcing phase, as well as in tissue engineering, pharmaceutical and optical industries as additives.

  7. Bacterial cellulose/boehmite composites

    Energy Technology Data Exchange (ETDEWEB)

    Salvi, Denise T.B. de; Barud, Hernane S.; Messaddeq, Younes; Ribeiro, Sidney J.L. [Universidade Estadual Paulista Julio de Mesquita Filho. UNESP. Instituto de Quimica de Araraquara, SP (Brazil); Caiut, Jose Mauricio A. [Universidade de Sao Paulo. Departamento de Quimica - FFCLRP/USP, Ribeirao Preto, SP (Brazil)


    Composites based on bacterial cellulose membranes and boehmite were obtained. SEM results indicate that the bacterial cellulose (BC) membranes are totally covered by boehmite and obtained XRD patterns suggest structural changes due to this boehmite addition. Thermal stability is accessed through TG curves and is dependent on boehmite content. Transparency is high comparing to pure BC as can be seen through UV-vis absorption spectroscopy. (author)

  8. High-yield production of extracellular type-I cellulose by the cyanobacterium Synechococcus sp. PCC 7002. (United States)

    Zhao, Chi; Li, Zhongkui; Li, Tao; Zhang, Yingjiao; Bryant, Donald A; Zhao, Jindong


    Cellulose synthase, encoded by the cesA gene, is responsible for the synthesis of cellulose in nature. We show that the cell wall of the cyanobacterium Synechococcus sp. PCC 7002 naturally contains cellulose. Cellulose occurs as a possibly laminated layer between the inner and outer membrane, as well as being an important component of the extracellular glycocalyx in this cyanobacterium. Overexpression of six genes, cmc-ccp-cesAB-cesC-cesD-bgl, from Gluconacetobacter xylinus in Synechococcus sp. PCC 7002 resulted in very high-yield production of extracellular type-I cellulose. High-level cellulose production only occurred when the native cesA gene was inactivated and when cells were grown at low salinity. This system provides a method for the production of lignin-free cellulose from sunlight and CO2 for biofuel production and other biotechnological applications.

  9. Techniques de conception des circuits intégrés analogiques pour des applications en haute température, en technologies de conception des circuits intégrés analogiques pour des applications en haute température, en technologies sur substrat de silicium


    Bianchi, R.A.


    ISBN: 2-913329-39-X; This Ph.D. deals with high temperature microelectronics for low-cost and high-volume applications. Present day most advanced microelectronic technologies, in terms of density, cost and reliability, still use silicon substrates. Theses technologies are designed to obtain long MTF (Mean Time to Failure) at normal temperatures: 0 to 100C, typically. Other technologies, such as Wide Bandgap Semiconductors (SiC, Diamond, etc.) and thin film SOI, are under development to provid...

  10. Surface modification of cellulose nanocrystals (United States)

    Eyley, Samuel; Thielemans, Wim


    Chemical modification of cellulose nanocrystals is an increasingly popular topic in the literature. This review analyses the type of cellulose nanocrystal modification reactions that have been published in the literature thus far and looks at the steps that have been taken towards analysing the products of the nanocrystal modifications. The main categories of reactions carried out on cellulose nanocrystals are oxidations, esterifications, amidations, carbamations and etherifications. More recently nucleophilic substitutions have been used to introduce more complex functionality to cellulose nanocrystals. Multi-step modifications are also considered. This review emphasizes quantification of modification at the nanocrystal surface in terms of degree of substitution and the validity of conclusions drawn from different analysis techniques in this area. The mechanisms of the modification reactions are presented and considered with respect to the effect on the outcome of the reactions. While great strides have been made in the quality of analytical data published in the field of cellulose nanocrystal modification, there is still vast scope for improvement, both in data quality and the quality of analysis of data. Given the difficulty of surface analysis, cross-checking of results from different analysis techniques is fundamental for the development of reliable cellulose nanocrystal modification techniques.

  11. Occurrence of Cellulose-Producing Gluconacetobacter spp. in Fruit Samples and Kombucha Tea, and Production of the Biopolymer. (United States)

    Neera; Ramana, Karna Venkata; Batra, Harsh Vardhan


    Cellulose producing bacteria were isolated from fruit samples and kombucha tea (a fermented beverage) using CuSO4 solution in modified Watanabe and Yamanaka medium to inhibit yeasts and molds. Six bacterial strains showing cellulose production were isolated and identified by 16S rRNA gene sequencing as Gluconacetobacter xylinus strain DFBT, Ga. xylinus strain dfr-1, Gluconobacter oxydans strain dfr-2, G. oxydans strain dfr-3, Acetobacter orientalis strain dfr-4, and Gluconacetobacter intermedius strain dfr-5. All the cellulose-producing bacteria were checked for the cellulose yield. A potent cellulose-producing bacterium, i.e., Ga. xylinus strain DFBT based on yield (cellulose yield 5.6 g/L) was selected for further studies. Cellulose was also produced in non- conventional media such as pineapple juice medium and hydrolysed corn starch medium. A very high yield of 9.1 g/L cellulose was obtained in pineapple juice medium. Fourier transform infrared spectrometer (FT-IR) analysis of the bacterial cellulose showed the characteristic peaks. Soft cellulose with a very high water holding capacity was produced using limited aeration. Scanning electron microscopy (SEM) was used to analyze the surface characteristics of normal bacterial cellulose and soft cellulose. The structural analysis of the polymer was performed using (13)C solid-state nuclear magnetic resonance (NMR). More interfibrillar space was observed in the case of soft cellulose as compared to normal cellulose. This soft cellulose can find potential applications in the food industry as it can be swallowed easily without chewing.

  12. Elaboration et caractérisation d'un vernis antireflet sol-gel innovant pour application dans les systèmes d'écrans embarqués en aéronautique


    Boudot, Mickael


    Low refractive index hydrophobic antireflective coatings were synthetized as mesoporous nanometric thin silica films by use of sol gel chemistry coupled with the dip coating process on thermo sensitive polymeric substrates such as poly(methyl methacrylate) (PMMA) and cellulose triacetate (TAC). Thin films of pure and hybrid silica were stiffened by ammonia vapor treatment (AVT) at room temperature. Optical, mechanical and chemical stability of those coatings were optimized and the AVT-induced ...

  13. Purification and biochemical properties of a thermostable, haloalkaline cellulase from Bacillus licheniformis AMF-07 and its application for hydrolysis of different cellulosic substrates to bioethanol production (United States)

    Azadian, Fatemeh; Badoei-dalfard, Arastoo; Namaki-Shoushtari, Abdolhamid; Hassanshahian, Mehdi


    A thermophilic strain AMF-07, hydrolyzing carboxymethylcellulose (CMC) was isolated from Kerman hot spring and was identified as Bacillus licheniformis based on 16S rRNA sequence homology. The carboxymethylcellulase (CMCase) enzyme produced by the B. licheniformis was purified by (NH4)2SO4 precipitation, ion exchange and gel filtration chromatography. The purified enzyme gave a single band on SDS- PAGE with a molecular weight of 37 kDa. The CMCase enzyme was highly active and stable over broad ranges of temperature (40-80ºC), pH (6.0-10.0) and NaCl concentration (10-25%) with an optimum at 70ºC, pH 9.0 and 20% NaCl, which showed excellent thermostable, alkali-stable and halostable properties. Moreover, it displayed high activity in the presence of cyclohexane (134%) and chloroform (120%). Saccharification of rice bran and wheat bran by the CMCase enzyme resulted in respective yields of 24 and 32 g L-1 reducing sugars. The enzymatic hydrolysates of rice bran were then used as the substrate for ethanol production by Saccharomyces cerevisiae. Fermentation of cellulosic hydrolysate using S. cerevisiae, reached maximum ethanol production about 0.125 g g-1 dry substrate (pretreated wheat bran). Thus, the purified cellulase from B. licheniformis AMF-07 utilizing lignocellulosic biomass could be greatly useful to develop industrial processes. PMID:28097168

  14. Purification and biochemical properties of a thermostable, haloalkaline cellulase from Bacillus licheniformis AMF-07 and its application for hydrolysis of different cellulosic substrates to bioethanol production

    Directory of Open Access Journals (Sweden)

    Fatemeh Azadian


    Full Text Available A thermophilic strain AMF-07, hydrolyzing carboxymethylcellulose (CMC was isolated from Kerman hot spring and was identified as Bacillus licheniformis based on 16S rRNA sequence homology. The carboxymethylcellulase (CMCase enzyme produced by the B. licheniformis was purified by (NH42SO4 precipitation, ion exchange and gel filtration chromatography. The purified enzyme gave a single band on SDS-PAGE with a molecular weight of 37 kDa. The CMCase enzyme was highly active and stable over broad ranges of temperature (40-80 ºC, pH (6.0-10.0 and NaCl concentration (10-25% with an optimum at 70 ºC, pH 9.0 and 20% NaCl, which showed excellent thermostable, alkali-stable and halostable properties. Moreover, it displayed high activity in the presence of cyclohexane (134% and chloroform (120%. Saccharification of rice bran and wheat bran by the CMCase enzyme resulted in respective yields of 24 and 32 g L-1 reducing sugars. The enzymatic hydrolysates of rice bran were then used as the substrate for ethanol production by Saccharomyces cerevisiae. Fermentation of cellulosic hydrolysate using S. cerevisiae, reached maximum ethanol production about 0.125 g g-1 dry substrate (pretreated wheat bran. Thus, the purified cellulase from B. licheniformis AMF-07 utilizing lignocellulosic biomass could be greatly useful to develop industrial processes.

  15. Variation in oxygen isotope fractionation during cellulose synthesis: intramolecular and biosynthetic effects. (United States)

    Sternberg, Leonel; Pinzon, Maria Camila; Anderson, William T; Jahren, A Hope


    The oxygen isotopic composition of plant cellulose is commonly used for the interpretations of climate, ecophysiology and dendrochronology in both modern and palaeoenvironments. Further applications of this analytical tool depends on our in-depth knowledge of the isotopic fractionations associated with the biochemical pathways leading to cellulose. Here, we test two important assumptions regarding isotopic effects resulting from the location of oxygen in the carbohydrate moiety and the biosynthetic pathway towards cellulose synthesis. We show that the oxygen isotopic fractionation of the oxygen attached to carbon 2 of the glucose moieties differs from the average fractionation of the oxygens attached to carbons 3-6 from cellulose by at least 9%, for cellulose synthesized within seedlings of two different species (Triticum aestivum L. and Ricinus communis L.). The fractionation for a given oxygen in cellulose synthesized by the Triticum seedlings, which have starch as their primary carbon source, is different than the corresponding fractionation in Ricinus seedlings, within which lipids are the primary carbon source. This observation shows that the biosynthetic pathway towards cellulose affects oxygen isotope partitioning, a fact heretofore undemonstrated. Our findings may explain the species-dependent variability in the overall oxygen isotope fractionation during cellulose synthesis, and may provide much-needed insight for palaeoclimate reconstruction using fossil cellulose.

  16. Binding Cellulose and Chitosan via Intermolecular Inclusion Interaction: Synthesis and Characterisation of Gel

    Directory of Open Access Journals (Sweden)

    Jiufang Duan


    Full Text Available A novel cellulose-chitosan gel was successfully prepared in three steps: (1 ferrocene- (Fc- cellulose with degrees of substitution (DS of 0.5 wt% was synthesised by ferrocenecarboxylic acid and cellulose within dimethylacetamide/lithium chloride (DMAc/LiCl; (2 the β-cyclodextrin (β-CD groups were introduced onto the chitosan chains by reacting chitosan with epichlorohydrin in dimethyl sulphoxide and a DS of 0.35 wt%; (3 thus, the cellulose-chitosan gel was obtained via an intermolecular inclusion interaction of Fc-cellulose and β-CD-chitosan in DMA/LiCl, that is, by an intermolecular inclusion interaction, between the Fc groups of cellulose and the β-CD groups on the chitosan backbone at room temperature. The successful synthesis of Fc-cellulose and β-CD-chitosan was characterised by 13C-NMR spectroscopy. The gel based on β-CD-chitosan and Fc-cellulose was formed under mild conditions which can engender autonomous healing between cut surfaces after 24 hours: the gel cannot self-heal while the cut surfaces were coated with a solution of a competitive guest (adamantane acid. The cellulose-chitosan complex made by this method underwent self-healing. Therefore, this study provided a novel method of expanding the application of chitosan by binding it with another polymer.

  17. Cellulose nanofibrils improve the properties of all-cellulose composites by the nano-reinforcement mechanism and nanofibril-induced crystallization (United States)

    Yang, Quanling; Saito, Tsuguyuki; Berglund, Lars A.; Isogai, Akira


    All-cellulose nanocomposite films containing crystalline TEMPO-oxidized cellulose nanofibrils (TOCNs) of 0-1 wt% were fabricated by mixing aqueous TOCN dispersions with alkali/urea/cellulose (AUC) solutions at room temperature. The mixtures were cast on glass plates, soaked in an acid solution, and the regenerated gel-like films were washed with water and then dried. The TOCN did not form agglomerates in the composites, and had the structure of TOCN-COOH, forming hydrogen bonds with the hydroxyl groups of the regenerated cellulose molecules. X-ray diffraction analysis revealed that the matrix cellulose molecules increased the cellulose II crystal size upon incorporation of TOCN. As a result, the TOCN/AUC composite films had high Young's modulus, tensile strength, thermal stability and oxygen-barrier properties. The TOCN/AUC composite films are promising all-cellulose nanocomposites for versatile applications as new bio-based materials.All-cellulose nanocomposite films containing crystalline TEMPO-oxidized cellulose nanofibrils (TOCNs) of 0-1 wt% were fabricated by mixing aqueous TOCN dispersions with alkali/urea/cellulose (AUC) solutions at room temperature. The mixtures were cast on glass plates, soaked in an acid solution, and the regenerated gel-like films were washed with water and then dried. The TOCN did not form agglomerates in the composites, and had the structure of TOCN-COOH, forming hydrogen bonds with the hydroxyl groups of the regenerated cellulose molecules. X-ray diffraction analysis revealed that the matrix cellulose molecules increased the cellulose II crystal size upon incorporation of TOCN. As a result, the TOCN/AUC composite films had high Young's modulus, tensile strength, thermal stability and oxygen-barrier properties. The TOCN/AUC composite films are promising all-cellulose nanocomposites for versatile applications as new bio-based materials. Electronic supplementary information (ESI) available: Fig. S1-S3 show an AFM image of TOCN, SEM

  18. 2株纤维素降解细菌处理白酒丢糟的应用特性%Application Characteristics of Two Cellulose-degradation Bacterial Strains in Waste Distiller's Grains from Liquor Producing

    Institute of Scientific and Technical Information of China (English)

    游玲; 周黎军; 罗刚; 陈思慧; 王涛


    Application features of two bacterial strains (No. G7B-58 and S522B-41) of Bacillus in the fermentation of waste distiller's grains from liquor producing were studied. It's found that the two strains can adapt to the environment of waste distiller's grains, when inoculated in the waste distiller's grains separately, the cellulose of waste distiller's grains reduced by 16.9%and 16.6%, and the protein of waste distiller's grains increased by 35.0%and 39.2%, respectively. In the case of two strains inoculated in the waste distiller's grains together, the cellulose of waste distiller's grains decompose by 21.1%, the protein increased by 41.1%and the acidity reduced by 86%, with significantly reducing of acid, starch and residual sugar at the same time. For the scale of 10 kg waste distiller's grains, inoculated with 2%of the bacterial suspension, and piled up six days was appropriate. The results showed that the strains in the spent grains harmless or Grains fodder production had a good prospect of application. The results showed that the two bacteria strains had a good prospect of application in pollution control of waste distiller's grains and feed industry.%对2株Bacillus属细菌在白酒丢糟中的生长及降解纤维素的情况进行了研究。发现2株菌均可在丢糟中生长良好;分别可使丢糟纤维素降低16.9%及16.6%,蛋白质增加35.0%及39.2%。2株菌等比例混合接种于丢糟(2%接种量,处理10 kg丢糟),堆积6 d后可使丢糟纤维素降解21.1%,蛋白增加41.1%,酸度降低86%;同时丢糟中淀粉、残糖、酸度等指标也有明显降低。结果显示该2株细菌在丢糟饲料生产或丢糟无害化处理方面有很好的应用前景。

  19. Application of a Detailed Emission Model for Heavy Duty Diesel Engine Simulations Application d'un modèle détaillé d'émissions pour la simulation de gros moteurs diesel

    Directory of Open Access Journals (Sweden)

    Magnusson I.


    Full Text Available A detailed chemical model describing the formation of soot and NO is applied to simulate emission formation in a heavy duty diesel engine. Cylinder flow and spray development is simulated using an engine CFD code - Speedstar. Combustion is described using a simple eddy break-up model. Modeling of the emission-chemistry/turbulent-flow interaction is based on a flamelet approach. Contrary to a typical flamelet concept, transport equations are solved for mass fractions of soot and NO. The reason being that these major emission constituencies are assumed to change slowly in comparison to typical time scales for chemical processes or transport processes important for combustion. Chemical reactions leading to production and destruction of soot and NO are, however, assumed to be fast. Soot and NO source terms are therefore evaluated from a flamelet library using a presumed probability density function and integrating over mixture fraction space. Results from simulations are compared to engine measurements inform of exhaust emission data and cylinder pressure. Un modèle avec chimie détaillée décrivant la formation des suies et du NO est appliqué à la simulation de la formation des polluants dans un gros moteur Diesel. L'écoulement et le spray sont modélisés avec le code de calcul Speedstar. La combustion est représentée par le modèle eddy break-up . La modélisation de l'interaction entre l'écoulement turbulent et la chimie des polluants est basée sur une approche de type flamelet . Cependant, à la différence d'autres travaux, des équations de transport pour les fractions massiques de suies et de NO sont résolues. Cela est justifié par la supposition que les temps caractéristiques de formation de ces composés sont longs comparés à ceux associés aux phénomènes de transport et aux réactions chimiques associées à la combustion. Cependant, les vitesses de réaction se rapportant aux suies et au NO sont supposées rapides. Cela

  20. Ionic liquid processing of cellulose. (United States)

    Wang, Hui; Gurau, Gabriela; Rogers, Robin D


    Utilization of natural polymers has attracted increasing attention because of the consumption and over-exploitation of non-renewable resources, such as coal and oil. The development of green processing of cellulose, the most abundant biorenewable material on Earth, is urgent from the viewpoints of both sustainability and environmental protection. The discovery of the dissolution of cellulose in ionic liquids (ILs, salts which melt below 100 °C) provides new opportunities for the processing of this biopolymer, however, many fundamental and practical questions need to be answered in order to determine if this will ultimately be a green or sustainable strategy. In this critical review, the open fundamental questions regarding the interactions of cellulose with both the IL cations and anions in the dissolution process are discussed. Investigations have shown that the interactions between the anion and cellulose play an important role in the solvation of cellulose, however, opinions on the role of the cation are conflicting. Some researchers have concluded that the cations are hydrogen bonding to this biopolymer, while others suggest they are not. Our review of the available data has led us to urge the use of more chemical units of solubility, such as 'g cellulose per mole of IL' or 'mol IL per mol hydroxyl in cellulose' to provide more consistency in data reporting and more insight into the dissolution mechanism. This review will also assess the greenness and sustainability of IL processing of biomass, where it would seem that the choices of cation and anion are critical not only to the science of the dissolution, but to the ultimate 'greenness' of any process (142 references).

  1. Emploi de la télédétection spatiale pour le suivi du développement de l'aquaculture semi-intensive : application au littoral de la province de Huelva (Andalousie, Espagne

    Directory of Open Access Journals (Sweden)

    Yves-F. Thomas


    Full Text Available L’imagerie satellitaire SPOT est employée pour suivre le développement de l’aquaculture, sur une décennie, dans les secteurs de marais et d’anciennes salines situés entre les embouchures du Guadiana et du Guadalquivir, en Andalousie atlantique (Espagne. La croissance du parcellaire est observée et mesurée. Les effets, visibles par télédétection, de cette occupation de l’espace sur l’environnement sont étudiés.

  2. Degradation of Cellulose%纤维素的降解

    Institute of Scientific and Technical Information of China (English)



    To overview degradation of cellulose in acid,light,heat and oxidant,and outlook its application prospects.%综述了纤维素在酸、光、热和氧化剂中发生的降解,并展望了其应用前景。

  3. Biodegradable polymer films from seaweed polysaccharides: A review on cellulose as a reinforcement material

    Directory of Open Access Journals (Sweden)

    H. P. S. Abdul Khalil


    Full Text Available Seaweed and cellulose are promising natural polymers. This article reviews the basic information and recent developments of both seaweed and cellulose biopolymer materials as well as analyses the feasible formation of seaweed/cellulose composite films. Seaweed and cellulose both exhibit interesting film-forming properties. Nevertheless, seaweed has poor water vapour barrier and mechanical properties, whereas cellulose is neither meltable nor soluble in water or common organic solvents due to its highly crystalline structure. Therefore, modification of these hydrocolloids has been done to exploit their useful properties. Blending of biopolymers is a must recommended approach to improve the desired characteristics. From the review, seaweed is well compatible with cellulose, which possesses excellent mechanical strength and water resistance properties. Moreover, seaweed/cellulose composite films can prolong a product’s shelf life while maintaining its biodegradability. Additionally, the films show potential in contributing to the bioeconomy. In order to widen seaweed and cellulose in biocomposite application across various industries, some of the viewpoints are highlighted to be focused for future developments and applications.

  4. Elucidating the Potential Biological Impact of Cellulose Nanocrystals

    Directory of Open Access Journals (Sweden)

    Sandra Camarero-Espinosa


    Full Text Available Cellulose nanocrystals exhibit an interesting combination of mechanical properties and physical characteristics, which make them potentially useful for a wide range of consumer applications. However, as the usage of these bio-based nanofibers increases, a greater understanding of human exposure addressing their potential health issues should be gained. The aim of this perspective is to highlight how knowledge obtained from studying the biological impact of other nanomaterials can provide a basis for future research strategies to deduce the possible human health risks posed by cellulose nanocrystals.

  5. Web application for the control and management of radioprotection equipment in the Cadarache centre; Application WEB pour le controle et la gestion des appareils de radioprotection sur le centre de Cadarache

    Energy Technology Data Exchange (ETDEWEB)



    The author describes a web 2-type application which has been developed for the periodic calibration controls of radioprotection equipment in Cadarache. This application aims at offering an easy and immediate and even remote access to information, at selecting information with respect to uses (radioprotection department, administrator, and so on), at securing and safeguarding homogeneous data, at editing control statistics. The different functionalities are briefly presented with their displayed interface

  6. High Yield Preparation Method of Thermally Stable Cellulose Nanofibers

    Directory of Open Access Journals (Sweden)

    Hongli Zhu


    Full Text Available The preparation of nanocellulose fibers (NFs is achieved through pretreating cellulose in a NaOH/urea/thiourea solution, and then defibrillating the fibers through ultrasonication, resulting in a high yield of 85.4%. Extensive work has been done to optimize the preparation parameters. The obtained NFs are about 30 nm in diameter with cellulose II crystal structure. They possess high thermal stability with an onset of thermal degradation at 270 °C and a maximum degradation temperature of 370 °C. Such NFs have potential applications in transistors and batteries with high thermal stability. NFs-H were obtained by homogenizing undefibrillated fibers separated from the preparation of NFs. NFs-H were also in cellulose II crystal form but with lower thermal stability due to low crystallinity. They can be applied to make highly transparent paper.

  7. Plant cellulose synthesis: CESA proteins crossing kingdoms. (United States)

    Kumar, Manoj; Turner, Simon


    Cellulose is a biopolymer of considerable economic importance. It is synthesised by the cellulose synthase complex (CSC) in species ranging from bacteria to higher plants. Enormous progress in our understanding of bacterial cellulose synthesis has come with the recent publication of both the crystal structure and biochemical characterisation of a purified complex able to synthesis cellulose in vitro. A model structure of a plant CESA protein suggests considerable similarity between the bacterial and plant cellulose synthesis. In this review article we will cover current knowledge of how plant CESA proteins synthesise cellulose. In particular the focus will be on the lessons learned from the recent work on the catalytic mechanism and the implications that new data on cellulose structure has for the assembly of CESA proteins into the large complex that synthesis plant cellulose microfibrils.

  8. Characterization of Cellulose Synthesis in Plant Cells

    Directory of Open Access Journals (Sweden)

    Samaneh Sadat Maleki


    Full Text Available Cellulose is the most significant structural component of plant cell wall. Cellulose, polysaccharide containing repeated unbranched β (1-4 D-glucose units, is synthesized at the plasma membrane by the cellulose synthase complex (CSC from bacteria to plants. The CSC is involved in biosynthesis of cellulose microfibrils containing 18 cellulose synthase (CesA proteins. Macrofibrils can be formed with side by side arrangement of microfibrils. In addition, beside CesA, various proteins like the KORRIGAN, sucrose synthase, cytoskeletal components, and COBRA-like proteins have been involved in cellulose biosynthesis. Understanding the mechanisms of cellulose biosynthesis is of great importance not only for improving wood production in economically important forest trees to mankind but also for plant development. This review article covers the current knowledge about the cellulose biosynthesis-related gene family.

  9. Biocompatibility of Bacterial Cellulose Based Biomaterials



    Some bacteria can synthesize cellulose when they are cultivated under adequate conditions. These bacteria produce a mat of cellulose on the top of the culture medium, which is formed by a three-dimensional coherent network of pure cellulose nanofibers. Bacterial cellulose (BC) has been widely used in different fields, such as the paper industry, electronics and tissue engineering due to its remarkable mechanical properties, conformability and porosity. Nanocomposites based on BC have received...


    Directory of Open Access Journals (Sweden)

    Fátima Vargas,


    Full Text Available The aim of this work was to study the potential application of four types of cereal straws: oats, maize, rapeseed, and barley, in order to obtain cellulose pulp through the Specel® process for use in the manufacture of 100% biodegradable and ecological packaging. Raw materials were chemically characterized to determine alcohol-extractives, ash, lignin, holocellulose, and α-cellulose. Cellulosic pulps obtained from raw materials were characterized to determine yield, Kappa number, and viscosity. Paper sheets made from cellulosic pulps were characterized to determine beating degree, tensile index, stretch, burst index, tear index, and brightness. Finally, the results were compared to the raw material used in the industrial manufacturing of packaging (wheat. The four studied raw materials (oats, maize, rapeseed, and barley were judged to be suitable for use in the Specel® process to obtain cellulosic pulp suitable for production of ecological containers.

  11. Microcrystalline-cellulose and polypropylene based composite: A simple, selective and effective material for microwavable packaging. (United States)

    Ummartyotin, S; Pechyen, C


    Cellulose based composite was successfully designed as active packaging with additional feature of microwavable properties. Small amount of cellulose with 10 μm in diameter was integrated into polypropylene matrix. The use of maleic anhydride was employed as coupling agent. Thermal and mechanical properties of cellulose based composite were superior depending on polypropylene matrix. Crystallization temperature and compressive strength were estimated to be 130 °C and 5.5 MPa. The crystal formation and its percentage were therefore estimated to be 50% and it can be predicted on the feasibility of microwavable packaging. Morphological properties of cellulose based composite presented the good distribution and excellent uniformity. It was remarkable to note that cellulose derived from cotton can be prepared as composite with polypropylene matrix. It can be used as packaging for microwave application.

  12. Possibility of cellulose-based electro-active paper energy scavenging transducer. (United States)

    Abas, Zafar; Kim, Heung Soo; Zhai, Lindong; Kim, Jaehwan; Kim, Joo Hyung


    In this paper, a cellulose-based Electro-Active Paper (EAPap) energy scavenging transducer is presented. Cellulose is proven as a smart material, and exhibits piezoelectric effect. Specimens were prepared by coating gold electrodes on both sides of cellulose film. The fabricated specimens were tested by a base excited aluminum cantilever beam at resonant frequency. Different tests were performed with single and multiple parallel connected electrodes coated on the cellulose film. A maximum of 131 mV output voltage was measured, when three electrodes were connected in parallel. It was observed that voltage output increases significantly with the area of electrodes. From these results, it can be concluded that the piezoelectricity of cellulose-based EAPap can be used in energy transduction application.

  13. The trafficking and behavior of cellulose synthase and a glimpse of potential cellulose synthesis regulators

    Institute of Scientific and Technical Information of China (English)

    Logan BASHLINE; Juan DU; Ying GU


    Cellulose biosynthesis is a topic of intensive research not only due to the significance of cellulose in the integrity of plant cell walls,but also due to the potential of using cellulose,a natural carbon source,in the production ot biofuels.Characterization of the composition,regulation,and trafficking of cellulose synthase complexes (CSCs) is critical to an understanding of cellulose biosynthesis as well as the characterization of additional proteins that contribute to the production of cellulose either through direct interactions with CSCs or through indirect mechanisms.In this review,a highlight of a few proteins that appear to affect cellulose biosynthesis,which includes:KORRIGAN (KOR),Cellulose Synthase-Interactive Protein 1 (CSI1),and the poplar microtubule-associated protein,PttMAP20,will accompany a description of cellulose synthase (CESA) behavior and a discussion of CESA trafficking compartments that might act in the regulation of cellulose biosynthesis.

  14. Atomic-scale modeling of cellulose nanocrystals (United States)

    Wu, Xiawa

    Cellulose nanocrystals (CNCs), the most abundant nanomaterials in nature, are recognized as one of the most promising candidates to meet the growing demand of green, bio-degradable and sustainable nanomaterials for future applications. CNCs draw significant interest due to their high axial elasticity and low density-elasticity ratio, both of which are extensively researched over the years. In spite of the great potential of CNCs as functional nanoparticles for nanocomposite materials, a fundamental understanding of CNC properties and their role in composite property enhancement is not available. In this work, CNCs are studied using molecular dynamics simulation method to predict their material' behaviors in the nanoscale. (a) Mechanical properties include tensile deformation in the elastic and plastic regions using molecular mechanics, molecular dynamics and nanoindentation methods. This allows comparisons between the methods and closer connectivity to experimental measurement techniques. The elastic moduli in the axial and transverse directions are obtained and the results are found to be in good agreement with previous research. The ultimate properties in plastic deformation are reported for the first time and failure mechanism are analyzed in details. (b) The thermal expansion of CNC crystals and films are studied. It is proposed that CNC film thermal expansion is due primarily to single crystal expansion and CNC-CNC interfacial motion. The relative contributions of inter- and intra-crystal responses to heating are explored. (c) Friction at cellulose-CNCs and diamond-CNCs interfaces is studied. The effects of sliding velocity, normal load, and relative angle between sliding surfaces are predicted. The Cellulose-CNC model is analyzed in terms of hydrogen bonding effect, and the diamond-CNC model compliments some of the discussion of the previous model. In summary, CNC's material properties and molecular models are both studied in this research, contributing to


    Energy Technology Data Exchange (ETDEWEB)

    Leschine, Susan


    Our research has dealt with seven major areas of investigation: i) characterization of cellulolytic members of microbial consortia, with special attention recently given to Clostridium phytofermentans, a bacterium that decomposes cellulose and produces uncommonly large amounts of ethanol, ii) investigations of the chitinase system of Cellulomonas uda; including the purification and characterization of ChiA, the major component of this enzyme system, iii) molecular cloning, sequence and structural analysis of the gene that encodes ChiA in C. uda, iv) biofilm formation by C. uda on nutritive surfaces, v) investigations of the effects of humic substances on cellulose degradation by anaerobic cellulolytic microbes, vi) studies of nitrogen metabolism in cellulolytic anaerobes, and vii) understanding the molecular architecture of the multicomplex cellulase-xylanase system of Clostridium papyrosolvens. Also, progress toward completing the research of more recent projects is briefly summarized. Major accomplishments include: 1. Characterization of Clostridium phytofermentans, a cellulose-fermenting, ethanol-producing bacterium from forest soil. The characterization of a new cellulolytic species isolated from a cellulose-decomposing microbial consortium from forest soil was completed. This bacterium is remarkable for the high concentrations of ethanol produced during cellulose fermentation, typically more than twice the concentration produced by other species of cellulolytic clostridia. 2. Examination of the use of chitin as a source of carbon and nitrogen by cellulolytic microbes. We discovered that many cellulolytic anaerobes and facultative aerobes are able to use chitin as a source of both carbon and nitrogen. This major discovery expands our understanding of the biology of cellulose-fermenting bacteria and may lead to new applications for these microbes. 3. Comparative studies of the cellulase and chitinase systems of Cellulomonas uda. Results of these studies indicate

  16. Atomic force microscopy study of cellulose surface interaction controlled by cellulose binding domains


    Nigmatullin, R.; Lovitt, R.; Wright, C; Linder, M.; Nakari-Setälä, T; Gama, F. M.


    Colloidal probe microscopy has been used to study the interaction between model cellulose surfaces and the role of cellulose binding domain (CBD), peptides specifically binding to cellulose, in interfacial interaction of cellulose surfaces modified with CBDs. The interaction between pure cellulose surfaces in aqueous electrolyte solution is dominated by double layer repulsive forces with the range and magnitude of the net force dependent on electrolyte concentration. AFM imaging reve...

  17. Physicotechnical, spectroscopic and thermogravimetric properties of powdered cellulose and microcrystalline cellulose derived from groundnut shells


    Chukwuemeka P. Azubuike; Jimson O. Odulaja; Augustine O Okhamafe


    α-Cellulose and microcrystalline cellulose powders, derived from agricultural waste products, that have for thepharmaceutical industry, desirable physical (flow) properties were investigated. α–Cellulose (GCN) wasextracted from groundnut shell (an agricultural waste product) using a non-dissolving method based oninorganic reagents. Modification of this α -cellulose was carried out by partially hydrolysing it with 2Nhydrochloric acid under reflux to obtain microcrystalline cellulose (MCGN). Th...

  18. 3D multi-layered fibrous cellulose structure using an electrohydrodynamic process for tissue engineering. (United States)

    Kim, Minseong; Kim, GeunHyung


    Micro/nanofibrous structures have been applied widely in various tissue-engineering applications because the topological structures are similar to the extracellular matrix (ECM), which encourages a high degree of cell adhesion and growth. However, it has been difficult to produce a three-dimensional (3D) fibrous structure using controllable macro-pores. Recently, cellulose has been considered a high-potential natural-origin biomaterial, but its use in 3D biomedical structures has been limited due to its narrow processing window. Here, we suggest a new 3D cellulose scaffold consisting of multi-layered struts made of submicron-sized entangled fibers that were fabricated using an electrohydrodynamic direct jet (EHDJ) process that is spin-printing. By optimizing processing conditions (electric field strength, cellulose feeding rate, and distance between nozzle and target), we can achieve a multi-layered cellulose structure consisting of the cylindrically entangled cellulose fibers. To compare the properties of the fabricated 3D cellulose structure, we used a PCL fibrous scaffold, which has a similar fibrous morphology and pore geometry, as a control. The physical and in vitro biocompatibilities of both fibrous scaffolds were assessed using human dermal fibroblasts, and the cellulose structure showed higher cell adhesion and metabolic activities compared with the control. These results suggest the EHDJ process to be an effective fabricating tool for tissue engineering and the cellulose scaffold has high potential as a tissue regenerative material.

  19. Cellulose nanocrystal from pomelo (C. Grandis osbeck) albedo: Chemical, morphology and crystallinity evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Zain, Nor Fazelin Mat; Yusop, Salma Mohamad [Food Science Program, School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Selangor (Malaysia); Ahmad, Ishak [Polymer Research Centre (PORCE), School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Selangor (Malaysia)


    Citrus peel is one of the under-utilized waste materials that have potential in producing a valuable fibre, which are cellulose and cellulose nanocrystal. Cellulose was first isolated from pomelo (C. Grandis Osbeck) albedo by combination of alkali treatment and bleaching process, followed by acid hydrolysis (65% H{sub 2}SO{sub 4}, 45 °C, 45min) to produce cellulose nanocrystal. The crystalline, structural, morphological and chemical properties of both materials were studied. Result reveals the crystallinity index obtained from X-ray diffraction for cellulose nanocrystal was found higher than extracted cellulose with the value of 60.27% and 57.47%, respectively. Fourier transform infrared showed that the chemical treatments removed most of the hemicellulose and lignin from the pomelo albedo fibre. This has been confirmed further by SEM and TEM for their morphological studies. These results showed that cellulose and cellulose nanocrystal were successfully obtained from pomelo albedo and might be potentially used in producing functional fibres for food application.

  20. Three-dimensional cellulose sponge: Fabrication, characterization, biomimetic mineralization, and in vitro cell infiltration. (United States)

    Joshi, Mahesh Kumar; Pant, Hem Raj; Tiwari, Arjun Prasad; Maharjan, Bikendra; Liao, Nina; Kim, Han Joo; Park, Chan Hee; Kim, Cheol Sang


    In this study, cellulose based scaffolds were produced by electrospinning of cellulose acetate (CA) solution followed by its saponification with NaOH/ethanol system for 24h. The resulting nonwoven cellulose mat was treated with sodium borohydride (SB) solution. In situ hydrolysis of SB solution into the pores of the membrane produced hydrogen gas resulting a three-dimensional (3D) cellulose sponge. SEM images demonstrated an open porous and loosely packed fibrous mesh compared to the tightly packed single-layered structure of the conventional electrospun membrane. 3D cellulose sponge showed admirable ability to nucleate bioactive calcium phosphate (Ca-P) crystals in simulated body fluid (SBF) solution. SEM-EDX and X-ray diffraction studies revealed that the minerals deposited on the nanofibers have the nonstoichiometric composition similar to that of hydroxyapatite, the mineralized component of the bone. 3D cellulose sponge exhibited the better cell infiltration, spreading and proliferation compared to 2D cellulose mat. Therefore, a facile fabrication of 3D cellulose sponge with improved mineralization represents an innovative strategy for the bone tissue engineering applications.

  1. Flammability of Cellulose-Based Fibers and the Effect of Structure of Phosphorus Compounds on Their Flame Retardancy

    Directory of Open Access Journals (Sweden)

    Khalifah A. Salmeia


    Full Text Available Cellulose fibers are promoted for use in various textile applications due their sustainable nature. Cellulose-based fibers vary considerably in their mechanical and flammability properties depending on their chemical composition. The chemical composition of a cellulose-based fiber is further dependent on their source (i.e., seed, leaf, cane, fruit, wood, bast, and grass. Being organic in nature, cellulose fibers, and their products thereof, pose considerable fire risk. In this work we have compared the flammability properties of cellulose fibers obtained from two different sources (i.e., cotton and peat. Compared to cotton cellulose textiles, peat-based cellulose textiles burn longer with a prominent afterglow which can be attributed to the presence of lignin in its structure. A series of phosphoramidates were synthesized and applied on both cellulose textiles. From thermogravimetric and pyrolysis combustion flow analysis of the treated cellulose, we were able to relate the flame retardant efficacy of the synthesized phosphorus compounds to their chemical structure. The phosphoramidates with methyl phosphoester groups exhibited higher condensed phase flame retardant effects on both types of cellulose textiles investigated in this study. In addition, the bis-phosphoramidates exhibited higher flame retardant efficacy compared to the mono-phosphoramidates.

  2. Synthèse d'un filtre de détection et isolation de défauts capteur pour les systèmes polytopiques LPV : application à un enrouleur de bandes


    Sahnoun, Mariem; Rodrigues, Mickael; Ponsart, Jean-Christophe; Theilliol, Didier


    International audience; Dans ce papier, une méthode de diagnostic de défauts est développée pour une classe particulière de systèmes non linéaires décrits sous une forme polytopique Linéaire à Paramètres Variants (LPV). La contribution principale consiste en la synthèse d'un filtre de Détection et d'Isolation de Défauts (DID) capteur et aussi en l'estimation de l'amplitude de défauts avec un facteur de qualité. Les conditions de stabilité du filtre polytopique LPV sont étudiées en assurant la...

  3. Modélisation bayésienne hiérarchique pour l'estimation de matrice de covariance - Application à la gestion actif-passif de portefeuilles financiers


    Bouriga, Mathilde; Féron, Olivier; Marin, Jean-Michel; Robert, Christian


    International audience; Ce papier concerne l'estimation de matrices de covariance dans le cas où le nombre de données utilisées pour l'estimation est faible par rapport à la dimension du problème et où les méthodes d'estimation classiques fondées sur le Maximum de Vraisemblance sont peu robustes. Nous proposons une méthode d'estimation non supervisée fondée sur une modélisation bayésienne hiérarchique du problème d'estimation de matrice de covariance : on pose une loi Inverse Wishart a priori...

  4. Synthese et utilisation de fibres cellulosiques phosphatees pour la valorisation de la fibre vegetale dans l'amelioration des proprietes de surface du papier et la fabrication de materiaux ignifuges (United States)

    Lentsolo Yalli, Gym Clerc

    Dans cette etude, nous souhaitions principalement greffer des groupements phosphates directement sur la cellulose comme materiau modele, et par la suite transposer les conditions optimales du design concu pour la cellulose, determine par modelisation a l'aide de l'outil JMP, sur la pate kraft. Ensuite, evaluer les proprietes physico-chimiques, optiques, d'hydrophilie, thermiques et d'inflammabilite des materiaux fabriques (feuilles ou pastilles fabriquees) a partir des fibres phosphorylees. Pour ce faire, nous avons pretraite la cellulose et la pate kraft dans une solution aqueuse de 10 a 15 % de LiCl a 70°C pendant 7 heures. Par la suite, nous avons procede a la reaction de phosphorylation in situ avec l'acide phosphorique et l'uree, dans des conditions de temperatures et de reactifs decrites par un design experimental, pendant 3 heures. La reaction de phosphorylation s'est realisee avec succes pour l'ensemble des resultats sur la cellulose, avec des taux de greffage variables selon les conditions operatoires. Les degres de substitutions (DSP), determines par ICP-OES, et les degres de polymerisation (DP), determines par viscosimetrie, etaient aussi variables, selon les conditions. L'etude des parametres experimentaux a permis de determiner les conditions optimales transposables sur la pate kraft (DSP = 1,47 et DP = 142,42 pour la cellulose, qui represente un taux de coupure de 38% de la fibre) et les facteurs critiques de la reaction. Les resultats de la reaction sur la fibre ont permis, non seulement de constater que les conditions utilisees pour la cellulose n'etaient directement transposables a la fibre, mais permettaient quand d'obtenir un DSP interessant ≥ a 1 avec un taux de coupure de 50 a 60 %. La structure du produit principal de la reaction (le sel de calcium du pyrophosphate d'ester de cellulose ou de pate kraft) a ete determinee par les analyses FTIR, XPS, RMN-13C et RMN-31P. L'etude de l'effet de la reaction de phosphorylation sur les proprietes

  5. Application d’une approche inspirée des colonies de fourmis pour la recommandation des chemins d’apprentissage dans un cours en ligne : modèle et expérience

    Directory of Open Access Journals (Sweden)

    Aziz Dahbi


    Full Text Available Dans cet article, nous présentons la mise en œuvre, l’expérimentation et l’évaluation d’une approche pour la recommandation des chemins d’apprentissage dans un cours en ligne. Le processus de recommandation est inspiré de l’intelligence en essaim et plus particulièrement de l’optimisation par colonies de fourmis (OCF (ant colony optimization [ACO]. Dans ce contexte, nous avons considéré une différenciation des chemins d’apprentissage en fonction de l’activité explorée pour l’apprentissage d’un cours. Dans l’objectif de recommander des chemins d’apprentissage considérés optimaux et d’évaluer ainsi leur impact sur l’apprentissage d’un cours en ligne, l’approche proposée est basée à la fois sur la recommandation de chemins pertinents par l’enseignant et sur les résultats stockés au fur et à mesure par les apprenants sur les chemins empruntés. Notre approche a été validée expérimentalement et les résultats obtenus ont montré l’émergence d’un chemin d’apprentissage favorisant la réussite d’un nombre d’apprenants relativement considérable.

  6. Measure of the temperature-depth profile by and S band radiometric receiver for biomedical applications; Mesure du profil de temperature en profondeur par un recepteur radiometrique a bande S pour applications biomedicales

    Energy Technology Data Exchange (ETDEWEB)

    Bri, S. [Universite My, Lab. de Genie Electrique de Meknes (LGEM), Dept. Genie Electrique, Meknes (Morocco); Bri, S.; Zenkouar, L.; Bellarbi, L. [Laboratoire d' Electronique et Communications (LEC), EMI, Rabat (Morocco); Saadi, A.; Habibi, M. [Universite Ibn Tofail, Lab. d' Automatique et de Micro-ondes (LAMO), Faculte des Sciences, Dept. de Physique, Kenitra (Morocco); Mamouni, A. [Lille-1 Univ., IEMN, UMR CNRS 8520, 59 - Villeneuve-d' Ascq (France)


    The authors present a method for measuring the temperature-depth profile in a lossy material by applying Kalman algorithm to radiometric signals. The method employs a correlation microwave radiometer. It uses both short-range weighting functions and the delay times of the correlator. An experimental verification of this new thermal inversion approach is presented. The thermal noise is received in the microwave domain, by a S band radiometer by using an automatic experimental bench. A feature of this method is that it can be used in biomedical applications. (author)

  7. Multi-scale structuration of the electrode-electrolyte interface for applications in bio-electro-catalysis; Structuration multi-echelle de l'interface electrode-electrolyte pour des applications en bioelectrocatalyse

    Energy Technology Data Exchange (ETDEWEB)

    Kuhn, A. [Bordeaux-1 Univ., LACReM, ENSCPB, 33 - Pessac (France)


    In this work, two approaches have been combined to elaborate bio-functionalized interfaces having an original structure and well defined at several characteristic scales. These two approaches are 1)the growth of conducting or non conducting materials through organized structures and 2)the chemistry of non-covalent intermolecular bonds leading to the assembling of molecules towards interfacial structures having greatest size. With a deep physico-chemical characterization, it has been possible to understand the properties of these multi-scale structures and to propose different applications fields as for instance bio-electro-catalysis or photovoltaic cells. (O.M.)

  8. Foaming of Ethyl Hydroxyethyl Cellulose


    Carrillo Agilera, Marc


    The current depletion of petroleum resources together with environmental issues have led to new approaches in plastic manufacturing. This trend involves using ecofriendly materials coming from renewable resources. Good candidates for this, due to their properties and availability, are the cellulose derivatives. Some of them, such as hydroxypropyl methylcellulose (HPMC), showed in previous studies a promising behavior when making polymeric foams. Unfortunately, the corresponding...

  9. Cellulose nanomaterials review: structure, properties and nanocomposites. (United States)

    Moon, Robert J; Martini, Ashlie; Nairn, John; Simonsen, John; Youngblood, Jeff


    This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them. It summarizes cellulose nanoparticles in terms of particle morphology, crystal structure, and properties. Also described are the self-assembly and rheological properties of cellulose nanoparticle suspensions. The methodology of composite processing and resulting properties are fully covered, with an emphasis on neat and high fraction cellulose composites. Additionally, advances in predictive modeling from molecular dynamic simulations of crystalline cellulose to the continuum modeling of composites made with such particles are reviewed (392 references).

  10. Biochemical Disincentives to Fertilizing Cellulosic Ethanol Crops (United States)

    Gallagher, M. E.; Hockaday, W. C.; Snapp, S.; McSwiney, C.; Baldock, J.


    Corn grain biofuel crops produce the highest yields when the cropping ecosystem is not nitrogen (N)-limited, achieved by application of fertilizer. There are environmental consequences for excessive fertilizer application to crops, including greenhouse gas emissions, hypoxic “dead zones,” and health problems from N runoff into groundwater. The increase in corn acreage in response to demand for alternative fuels (i.e. ethanol) could exacerbate these problems, and divert food supplies to fuel production. A potential substitute for grain ethanol that could reduce some of these impacts is cellulosic ethanol. Cellulosic ethanol feedstocks include grasses (switchgrass), hardwoods, and crop residues (e.g. corn stover, wheat straw). It has been assumed that these feedstocks will require similar N fertilization rates to grain biofuel crops to maximize yields, but carbohydrate yield versus N application has not previously been monitored. We report the biochemical stocks (carbohydrate, protein, and lignin in Mg ha-1) of a corn ecosystem grown under varying N levels. We measured biochemical yield in Mg ha-1 within the grain, leaf and stem, and reproductive parts of corn plants grown at seven N fertilization rates (0-202 kg N ha-1), to evaluate the quantity and quality of these feedstocks across a N fertilization gradient. The N fertilization rate study was performed at the Kellogg Biological Station-Long Term Ecological Research Site (KBS-LTER) in Michigan. Biochemical stocks were measured using 13C nuclear magnetic resonance spectroscopy (NMR), combined with a molecular mixing model (Baldock et al. 2004). Carbohydrate and lignin are the main biochemicals of interest in ethanol production since carbohydrate is the ethanol feedstock, and lignin hinders the carbohydrate to ethanol conversion process. We show that corn residue carbohydrate yields respond only weakly to N fertilization compared to grain. Grain carbohydrate yields plateau in response to fertilization at

  11. Teores de lignina e celulose em plantas de cana-de-açúcar em função da aplicação de maturadores Lignin and cellulose contents in sugarcane after ripener application

    Directory of Open Access Journals (Sweden)

    D.K. Meschede


    Full Text Available O objetivo deste trabalho foi avaliar os teores de lignina e celulose em plantas de cana-de-açúcar após a aplicação de dois maturadores para a colheita. O experimento foi conduzido em uma área de cana-soca, cultivar SP 803280, no município de Igaraçu do Tietê/SP. O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições. Os tratamentos constituíram-se da aplicação de dois maturadores: sulfometuron-methyl (Curavial e glyphosate (Roundup original. As doses utilizadas foram: glyphosate a 72 g e.a. ha-1; glyphosate a 144 g e.a. ha-1 ; glyphosate a 72 g e.a. ha-1 + sulfometuron methyl a 10 g p.c. ha-1; glyphosate a 108 g e.a. ha-1 + sulfometuron-methyl a 12 g p.c. ha-1; sulfometuron-methyl a 20 g p.c. ha-1; e a testemunha sem aplicação de maturadores. As análises de lignina e celulose foram realizadas pelo método lignina em detergente ácido modificado. O glyphosate e o sulfometuron-methyl alteraram os níveis de lignina no momento da colheita, e esse efeito foi observado também durante o crescimento da cana-de-açúcar (meses após a aplicação desses produtos. O glyphosate a 72 g e.a. ha-1 promoveu reduções nos teores de lignina, na colheita e durante o crescimento da cana-de-açúcar, quando comparados com os da testemunha, enquanto o sulfometuron-methyl isolado na menor dose (10 g ha-1 promoveu aumento nos teores desse biopolímero na soqueira da cana-de-açúcar.The aim of this study was to evaluate the content of lignin and cellulose in sugarcane after application of ripeners. The experiment was carried out in a sugarcane ratoon area, variety SP803280 in Igaraçu Tietê, São Paulo, Brazil. The experimental design was a randomized complete block with four replications. The treatments consisted of application of two ripeners: sulfometuron methyl (Curavial and glyphosate (Roundup Original. The doses used were: glyphosate 200 mL pc ha-1; glyphosate at 400 mL p.c. ha-1, glyphosate at 200 mL p

  12. Communication and Sensing Circuits on Cellulose

    Directory of Open Access Journals (Sweden)

    Federico Alimenti


    Full Text Available This paper proposes a review of several circuits for communication and wireless sensing applications implemented on cellulose-based materials. These circuits have been developed during the last years exploiting the adhesive copper laminate method. Such a technique relies on a copper adhesive tape that is shaped by a photo-lithographic process and then transferred to the hosting substrate (i.e., paper by means of a sacrificial layer. The presented circuits span from UHF oscillators to a mixer working at 24 GHz and constitute an almost complete set of building blocks that can be applied to a huge variety communication apparatuses. Each circuit is validated experimentally showing performance comparable with the state-of-the-art. This paper demonstrates that circuits on cellulose are capable of operating at record frequencies and that ultra- low cost, green i.e., recyclable and biodegradable materials can be a viable solution to realize high frequency hardware for the upcoming Internet of Things (IoT era.

  13. 抗菌纤维素/纤维素纤维的研究进展%Research progress of antibacterial cellulose/cellulose fiber

    Institute of Scientific and Technical Information of China (English)

    徐永建; 左磊刚


    介绍了常用的无机抗菌剂和有机抗菌剂的种类及其抗菌机理,阐述了载银抗菌纤维素、纳米TiO2抗菌纤维素、季铵盐类抗菌纤维素、壳聚糖改性抗菌纤维素等抗菌纤维素及其在纺织工业、膜材料等方面的应用。指出了根据所选抗菌剂的不同,通过化学或物理方法可对纤维素和纤维素纤维进行抗菌改性。绒毛浆是一次性卫生用品吸水性垫层用绒毛化的纤维素纤维,对绒毛浆进行抗菌性改性能够提高绒毛浆的品质和功能。提出了可用于绒毛浆纤维抗菌性改性的抗菌剂和可能的方法,抗菌纤维素纤维改性在绒毛浆生产和应用中存在潜在应用前景。同时,提出了抗菌纤维素/纤维素纤维在生产和应用中存在的问题和解决办法。%The commonly used inorganic antibacterial agent and organic antibacterial agent , and their types and antibacterial mechanism were introduced .Silver antibacterial cellulose , nano TiO2 antibacterial cellulose , quaternary ammonium antibacterial cellulose , chitosan modified bacterial cellulose and other antimicrobial cellulose and its application in the textile industry ,film material and other applications were elaborated .According to the selected type of antibacterial agent ,cellulose and cellulose fibers can be modified by chemical or physical method ,fluff pulp is fluffed cellulose fibers used in disposable sanitary absorbent mat ,and fluff pulp can improve its quality and function by antibacterial modified .Paper introduced the possible antimicrobial agent and methods can be used in the antibacterial modified of fluff pulp fibers ,and the potential prospect of antibacterial modified of cellulose fibers in the pro-duction and application fluff pulp .Meanwhile the problems and solutions were presented in the production and application of antibacterial cellulose and cellulose fiber .

  14. Modelization, fabrication and evaluation avalanche photodiodes polarized in Geiger mode for the single photon in astrophysics applications; Modelisation, fabrication et evaluation des photodiodes a avalanche polarisees en mode Geiger pour la detection du photon unique dans les applications Astrophysiques

    Energy Technology Data Exchange (ETDEWEB)

    Pellion, D


    The genesis of the work presented in this this is in the field of very high energy astrophysics. One century ago, scientists identified a new type of messenger coming from space: cosmic rays. This radiation consists of particles (photons or other) of very high energy which bombard the Earth permanently. The passage of cosmic radiations in the Earth's atmosphere results in the creation of briefs luminous flashes (5 ns) of very low intensity (1 pW), a Cherenkov flash, and then becomes visible on the ground. In the current state of the art the best detector of light today is the Photomultiplier tube (PMT), thanks to its characteristics of sensitivity and speed. But there are some drawbacks: low quantum efficiency, cost, weight etc. We present in this thesis a new alternative technology: silicon photon counters, made of photodiodes polarized in Geiger mode. This operating mode makes it possible to obtain an effect of multiplication comparable to that of the PMT. A physical and electrical model was developed to reproduce the behaviour of this detector. We then present in this thesis work an original technological process allowing the realization of these devices in the Center of Technology of LAAS-CNRS, with the simulation of each operation of the process. We developed a scheme for the electric characterization of the device, from the static mode to the dynamic mode, in order to check conformity with SILVACO simulations and to the initial model. Results are already excellent, given this is only a first prototype step, and comparable with the results published in the literature. These silicon devices can intervene in all the applications where there is a photomultiplier and replace it. The applications are thus very numerous and the growth of the market of these detectors is very fast. We present a first astrophysical experiment installed at the 'Pic du Midi' site which has detected Cherenkov flashes from cosmic rays with this new semiconductor technology

  15. Cellulose nanomaterials in water treatment technologies. (United States)

    Carpenter, Alexis Wells; de Lannoy, Charles-François; Wiesner, Mark R


    Cellulose nanomaterials are naturally occurring with unique structural, mechanical and optical properties. While the paper and packaging, automotive, personal care, construction, and textiles industries have recognized cellulose nanomaterials' potential, we suggest cellulose nanomaterials have great untapped potential in water treatment technologies. In this review, we gather evidence of cellulose nanomaterials' beneficial role in environmental remediation and membranes for water filtration, including their high surface area-to-volume ratio, low environmental impact, high strength, functionalizability, and sustainability. We make direct comparison between cellulose nanomaterials and carbon nanotubes (CNTs) in terms of physical and chemical properties, production costs, use and disposal in order to show the potential of cellulose nanomaterials as a sustainable replacement for CNTs in water treatment technologies. Finally, we comment on the need for improved communication and collaboration across the myriad industries invested in cellulose nanomaterials production and development to achieve an efficient means to commercialization.

  16. Conception d'un circuit d'etouffement pour photodiodes a avalanche en mode geiger pour integration heterogene 3d (United States)

    Boisvert, Alexandre

    Le Groupe de Recherche en Appareillage Medical de Sherbrooke (GRAMS) travaille actuellement sur un programme de recherche portant sur des photodiodes a avalanche mono-photoniques (PAMP) operees en mode Geiger en vue d'une application a la tomographie d'emission par positrons (TEP). Pour operer dans ce mode; la PAMP, ou SPAD selon l'acronyme anglais (Single Photon Avalanche Diode), requiert un circuit d'etouffement (CE) pour, d'une part, arreter l'avalanche pouvant causer sa destruction et, d'autre part. la reinitialiser en mode d'attente d'un nouveau photon. Le role de ce CE comprend egalement une electronique de communication vers les etages de traitement avance de signaux. La performance temporelle optimale du CE est realisee lorsqu'il est juxtapose a la PAMP. Cependant, cela entraine une reduction de la surface photosensible ; un element crucial en imagerie. L'integration 3D, a base d'interconnexions verticales, offre une solution elegante et performante a cette problematique par l'empilement de circuits integres possedant differentes fonctions (PAMP, CE et traitement avance de signaux). Dans l'approche proposee, des circuits d'etouffement de 50 pm x 50 pm realises sur une technologie CMOS 130 mn 3D Tezzaron, contenant chacun 112 transistors, sont matrices afin de correspondre a une matrice de PAMP localisee sur une couche electronique superieure. Chaque circuit d'etouffement possede une gigue temporelle de 7,47 ps RMS selon des simulations faites avec le logiciel Cadence. Le CE a la flexibilite d'ajuster les temps d'etouffement et de recharge pour la PAMP tout en presentant une faible consommation de puissance (~ 0,33 mW a 33 Mcps). La conception du PAMP necessite de supporter des tensions superieures aux 3,3 V de la technologie. Pour repondre a ce probleme, des transistors a drain etendu (DEMOS) ont ete realises. En raison de retards de production par Ies fabricants, les circuits n'ont pu etre testes physiquement par des mesures. Les resultats de ce memoire

  17. Degradation of cellulose in the presence of ash; Nedbrytningsmoenster foer cellulosa i naervaro av aska

    Energy Technology Data Exchange (ETDEWEB)

    Wikman, Karin; Berg, Magnus [AaF-Energi och Miljoe AB, Stockholm (Sweden); Svensson, Malin; Ecke, Holger [Luleaa Univ. of Tech. (Sweden)


    metals in combinations of ash and cellulose could also be caused by complex binding between solvent acids from the degradation of cellulose and metals in the ash. The experiments in this study have shown that the degradation product ISA results in an increased content of Pb and Zn in the leaching water from fly ash. When the experimental conditions were set to comparable conditions as for a compact and covered deposit after 250 years the leaching of Pb increased from 31 to 39 % and the leaching of Zn from 1,8 to 2,3 % when the content of ISA was increased 20 times. The disadvantages of mixing ash and cellulose are probably more important than the advantages because of the risk for increased metal mobilization. However, in some applications, for example grouting of ash to stabilize a waste deposit, the risk for metal leaching have to be compared to the advantages of using the ash. The disadvantages with ash and cellulose combinations could also be turned to advantages in special applications with processes where complex binding with ISA could give a selective washing/leaching and simultaneously the remaining metals could be fixed through carbonation.


    Energy Technology Data Exchange (ETDEWEB)

    Leschine, Susan


    Our research has dealt with seven major areas of investigation: i) characterization of cellulolytic members of microbial consortia, with special attention recently given to Clostridium phytofermentans, a bacterium that decomposes cellulose and produces uncommonly large amounts of ethanol, ii) investigations of the chitinase system of Cellulomonas uda; including the purification and characterization of ChiA, the major component of this enzyme system, iii) molecular cloning, sequence and structural analysis of the gene that encodes ChiA in C. uda, iv) biofilm formation by C. uda on nutritive surfaces, v) investigations of the effects of humic substances on cellulose degradation by anaerobic cellulolytic microbes, vi) studies of nitrogen metabolism in cellulolytic anaerobes, and vii) understanding the molecular architecture of the multicomplex cellulase-xylanase system of Clostridium papyrosolvens. Also, progress toward completing the research of more recent projects is briefly summarized. Major accomplishments include: 1. Characterization of Clostridium phytofermentans, a cellulose-fermenting, ethanol-producing bacterium from forest soil. The characterization of a new cellulolytic species isolated from a cellulose-decomposing microbial consortium from forest soil was completed. This bacterium is remarkable for the high concentrations of ethanol produced during cellulose fermentation, typically more than twice the concentration produced by other species of cellulolytic clostridia. 2. Examination of the use of chitin as a source of carbon and nitrogen by cellulolytic microbes. We discovered that many cellulolytic anaerobes and facultative aerobes are able to use chitin as a source of both carbon and nitrogen. This major discovery expands our understanding of the biology of cellulose-fermenting bacteria and may lead to new applications for these microbes. 3. Comparative studies of the cellulase and chitinase systems of Cellulomonas uda. Results of these studies indicate

  19. Bayesian methods to restore and re build images: application to gamma-graphy and to photofission tomography; Methodes bayesiennes pour la restauration et la reconstruction d`images application a la gammagraphie et a la tomographie par photofissions

    Energy Technology Data Exchange (ETDEWEB)

    Stawinski, G


    Bayesian algorithms are developed to solve inverse problems in gamma imaging and photofission tomography. The first part of this work is devoted to the modeling of our measurement systems. Two models have been found for both applications: the first one is a simple conventional model and the second one is a cascaded point process model. EM and MCMC Bayesian algorithms for image restoration and image reconstruction have been developed for these models and compared. The cascaded point process model does not improve significantly the results previously obtained by the classical model. To original approaches have been proposed, which increase the results previously obtained. The first approach uses an inhomogeneous Markov Random Field as a prior law, and makes the regularization parameter spatially vary. However, the problem of the estimation of hyper-parameters has not been solved. In the case of the deconvolution of point sources, a second approach has been proposed, which introduces a high level prior model. The picture is modeled as a list of objects, whose parameters and number are unknown. The results obtained with this method are more accurate than those obtained with the conventional Markov Random Field prior model and require less computational costs. (author)

  20. Optimization of the scintillation parameters of the lead tungstate crystals for their application in high precision electromagnetic calorimetry; Optimisation des parametres de scintillation des cristaux de tungstate de plomb pour leur application dans la calorimetrie electromagnetique de haute precision

    Energy Technology Data Exchange (ETDEWEB)

    Drobychev, G


    In the frame of this dissertation work scintillation properties of the lead tungstate crystals (PWO) and possibilities of their use were studied foreseeing their application for electromagnetic calorimetry in extreme radiation environment conditions of new colliders. The results of this work can be summarized in the following way. 1. A model of the scintillations origin in the lead tungstate crystals which includes processes influencing on the crystals radiation hardness and presence of slow components in scintillations was developed. 2. An analysis of the influences of the PWO scintillation properties changes on the parameters of the electromagnetic calorimeter was done. 3. Methods of the light collection from the large scintillation elements of complex shape made of the birefringent scintillation crystal with high refraction index and low light yield in case of signal registration by a photodetector with sensitive surface small in compare with the output face of scintillator were Studied. 4. Physical principles of the methodology of the scintillation crystals certification during their mass production foreseeing their installation into a calorimeter electromagnetic were developed. Correlations between the results of measurements of the PWO crystals parameters by different methods were found. (author)

  1. Observer design for non linear systems: application to automatic fault detection in process engineering; Synthese d'observateurs pour les systemes non lineaires. Application a la detection automatique de pannes en genie des procedes

    Energy Technology Data Exchange (ETDEWEB)

    Armanet, F.


    This thesis describes some theoretical contributions in state observer design for non linear systems and the conception of an automatic fault detector system for a petrochemical process. The first chapter is an overview of the observer theory for non linear systems. The second chapter presents a new methodology of high gain observer design for single-output U-uniformly observable systems. It consists in calculate a symmetric positive definite matrix which allows the design of an high gain observer which is exponentially converging. This observer is applied to estimate the concentrations in a perfectly mixed tank reactor with a kinetic scheme corresponding to the conversion of a product A onto a product B which is also converting onto a product C. In the third chapter, the use of high gain observer is extended for systems which are not uniformly observable but all admissible inputs are locally regularly persistent. A characterization of some of this class of inputs is given and an application for the preceding reactor illustrates this theory. The fourth chapter includes a summary of the observer used in residual generator design for linear and non linear systems. Two examples of automatic fault detector using these methods are describes. In annexed documents, a detailed study of the process modeling and the main observability properties are presented. (author)

  2. Macroscopic models for single-phase flows in fractured porous medium: application to well tests; Modeles macroscopiques pour les ecoulements monophasiques en milieu poreux fracture: application aux tests de puits

    Energy Technology Data Exchange (ETDEWEB)

    Landereau, P.


    We consider pressure diffusion in fractured media, with application to well test interpretation. Using the volume averaging theory of Quintard and Whitaker, the local problem is replaced by a double-porosity large scale description. The parameters of the latter may be computed solving small scale closure problems on a representative volume. Using suitable numerical methods, we have performed a systematic study of these parameters as a function of the topology of the fracture network and matrix to fracture permeability contrast. We find that the matrix permeability plays a significant role near a percolation threshold. Next, we studied the exchange coefficient parameter, by unifying the different definitions of the literature in a single framework using a Fourier analysis. Finally, we applied our technique to well-test interpretation in fractured media by comparing large scale solutions to high resolution direct simulations. We find that at short time scale, very fine grid blocks are needed to get good accuracy. In that case, a good agreement is observed between large scale averaged results and reference simulations. (author)

  3. A comparison of partially acetylated nanocellulose, nanocrystalline cellulose, and nanoclay as fillers for high-performance polylactide nanocomposites

    DEFF Research Database (Denmark)

    Trifol Guzman, Jon; Plackett, David; Sillard, Cecile


    Partially acetylated cellulose nanofibers (CNF) were chemically extracted from sisal fibers and the performance of those CNF as nanofillers for polylactide (PLA) for food packaging applications was evaluated. Three PLA nanocomposites; PLA/CNF (cellulose nanofibers), PLA/CNC (nanocrystalline cellu...

  4. Study of optically stimulated luminescence (OSL) for radiation detection. Application to an optical fibre {gamma}-radiation sensor; Etude de la luminescence stimulee optiquement (OSL) pour la detection de rayonnements: application a un capteur a fibre optique de rayonnement {gamma}

    Energy Technology Data Exchange (ETDEWEB)

    Roy, O. [CEA Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Electronique et d`Instrumentation Nucleaire]|[Paris-7 Univ., 75 (France)


    This work shows up the usefulness of the Optically Stimulated Luminescence (OSL) to resolve radioprotection problems. We study the use of OSL as a gamma dosimetric technique with respect to the ALARA`s concept (As Low As Reasonably Achievable). A new approach based on optical fibers and luminescent materials showing OSL properties (closely related to Thermoluminescence phenomena) is presented in order to improve the remote real time dosimetry monitoring. Like thermoluminescent materials (TLD), OSL materials can trap charges under an irradiation (UV, X, {gamma},...). Instead of heating, the charges trapped are released by light stimulation and produce a visible luminescence which amount is proportional to trap the `data stored` left by irradiation, enabling the dose measurement. The OSL phenomenon offers the same advantages as TLD plus the interesting possibility of a remote optical stimulation. The end-user objective deals with the development of a {gamma}-radiation Optical FIber Sensor (OFS) for dose measurement which can offer new functionalities based on OSL materials coupled with an optical fiber. Rare earth doped Alkaline Earth Sulphides (AES), BAFX:EU{sup 2+} (X = Cl, Br, I) and halogen alkaline have been studied (crystalline form, synthesis techniques, influence of dopants and color centers). Their characteristics are presented and extensively discussed. A specific experimental set-up to characterise various OSL phosphors has been developed. It allows the study of sensitivity, linearity, time decay behaviour of OSL signal and zeroing time. A joint study of OSL and TL has shown the technical limitations as well as the thermal fading and the origin of the long zeroing time. An Optical Fiber Sensor (OFS) based on OSL and using MgS:Sm has been developed for practical applications on nuclear fields. Its specifications are presented and discussed, moreover improvements are proposed. (author) 320 refs.

  5. A Statistical Treatment of Bioassay Pour Fractions (United States)

    Barengoltz, Jack; Hughes, David W.


    The binomial probability distribution is used to treat the statistics of a microbiological sample that is split into two parts, with only one part evaluated for spore count. One wishes to estimate the total number of spores in the sample based on the counts obtained from the part that is evaluated (pour fraction). Formally, the binomial distribution is recharacterized as a function of the observed counts (successes), with the total number (trials) an unknown. The pour fraction is the probability of success per spore (trial). This distribution must be renormalized in terms of the total number. Finally, the new renormalized distribution is integrated and mathematically inverted to yield the maximum estimate of the total number as a function of a desired level of confidence ( P(fraction. The extension to recovery efficiency corrections is also presented. Now the product of recovery efficiency and pour fraction may be small enough that the likely value may be much larger than the usual calculation: the number of spores divided by that product. The use of this analysis would not be limited to microbiological data.

  6. Cellulose nanocrystal submonolayers by spin coating. (United States)

    Kontturi, Eero; Johansson, Leena-Sisko; Kontturi, Katri S; Ahonen, Päivi; Thüne, Peter C; Laine, Janne


    Dilute concentrations of cellulose nanocrystal solutions were spin coated onto different substrates to investigate the effect of the substrate on the nanocrystal submonolayers. Three substrates were probed: silica, titania, and amorphous cellulose. According to atomic force microscopy (AFM) images, anionic cellulose nanocrystals formed small aggregates on the anionic silica substrate, whereas a uniform two-dimensional distribution of nanocrystals was achieved on the cationic titania substrate. The uniform distribution of cellulose nanocrystal submonolayers on titania is an important factor when dimensional analysis of the nanocrystals is desired. Furthermore, the amount of nanocrystals deposited on titania was multifold in comparison to the amounts on silica, as revealed by AFM image analysis and X-ray photoelectron spectroscopy. Amorphous cellulose, the third substrate, resulted in a somewhat homogeneous distribution of the nanocrystal submonolayers, but the amounts were as low as those on the silica substrate. These differences in the cellulose nanocrystal deposition were attributed to electrostatic effects: anionic cellulose nanocrystals are adsorbed on cationic titania in addition to the normal spin coating deposition. The anionic silica surface, on the other hand, causes aggregation of the weakly anionic cellulose nanocrystals which are forced on the repulsive substrate by spin coating. The electrostatically driven adsorption also influences the film thickness of continuous ultrathin films of cellulose nanocrystals. The thicker films of charged nanocrystals on a substrate of opposite charge means that the film thickness is not independent of the substrate when spin coating cellulose nanocrystals in the ultrathin regime (<100 nm).

  7. Preparation and properties of biodegradable films from Sterculia urens short fiber/cellulose green composites. (United States)

    Jayaramudu, J; Reddy, G Siva Mohan; Varaprasad, K; Sadiku, E R; Sinha Ray, S; Varada Rajulu, A


    The development of commercially viable "green products", based on natural resources for the matrices and reinforcements, in a wide range of applications, is on the rise. The present paper focuses on Sterculia urens short fiber reinforced pure cellulose matrix composite films. The morphologies of the untreated and 5% NaOH (alkali) treated S. urens fibers were observed by SEM. The effect of 5% NaOH treated S. urens fiber (5, 10, 15 and 20% loading) on the mechanical properties and thermal stability of the composites films is discussed. This paper presents the developments made in the area of biodegradable S. urens short fiber/cellulose (SUSF/cellulose) composite films, buried in the soil and later investigated by the (POM), before and after biodegradation has taken place. SUSF/cellulose composite films have great potential in food packaging and for medical applications.

  8. Bacterial Cellulose (BC) as a Functional Nanocomposite Biomaterial (United States)

    Nandgaonkar, Avinav Ghanashyam

    Cellulosic is the most abundant biopolymer in the landscape and can be found in many different organisms. It has been already seen use in the medical field, for example cotton for wound dressings and sutures. Although cellulose is naturally occurring and has found a number of applications inside and outside of the medical field, it is not typically produced in its pure state. A lengthy process is required to separate the lignin, hemicelluloses and other molecules from the cellulose in most renewables (wood, agricultural fibers such as cotton, monocots, grasses, etc.). Although bacterial cellulose has a similar chemical structure to plant cellulose, it is easier to process because of the absence of lignin and hemicelluloses which require a lot of energy and chemicals for removal. Bacterial cellulose (BC) is produced from various species of bacteria such as Gluconacetobacter xylinus. Due to its high water uptake, it has the tendency to form gels. It displays high tensile strength, biocompatibility, and purity compared to wood cellulose. It has found applications in fields such as paper, paper products, audio components (e.g., speaker diaphragms), flexible electronics, supercapacitors, electronics, and soft tissue engineering. In my dissertation, we have functionalized and studied BC-based materials for three specific applications: cartilage tissue engineering, bioelectronics, and dye degradation. In our first study, we prepared a highly organized porous material based on BC by unidirectional freezing followed by a freeze-drying process. Chitosan was added to impart additional properties to the resulting BC-based scaffolds that were evaluated in terms of their morphological, chemical, and physical properties for cartilage tissue engineering. The properties of the resulting scaffold were tailored by adjusting the concentration of chitosan over 1, 1.5, and 2 % (by wt-%). The scaffolds containing chitosan showed excellent shape recovery and structural stability after

  9. Functional biocompatible magnetite-cellulose nanocomposite fibrous networks: Characterization by fourier transformed infrared spectroscopy, X-ray powder diffraction and field emission scanning electron microscopy analysis. (United States)

    Habibi, Neda


    The preparation and characterization of functional biocompatible magnetite-cellulose nano-composite fibrous material is described. Magnetite-cellulose nano-composite was prepared by a combination of the solution-based formation of magnetic nano-particles and subsequent coating with amino celluloses. Characterization was accomplished using X-ray powder diffraction (XRD), fourier transformed infrared (FTIR) and field emission scanning electron microscopy (FESEM) analysis. The peaks of Fe3O4 in the XRD pattern of nanocomposite confirm existence of the nanoparticles in the amino cellulose matrix. Magnetite-cellulose particles exhibit an average diameter of roughly 33nm as demonstrated by field emission scanning electron microscopy. Magnetite nanoparticles were irregular spheres dispersed in the cellulose matrix. The vibration corresponding to the NCH3 functional group about 2850cm(-1) is assigned in the FTIR spectra. Functionalized magnetite-cellulose nano-composite polymers have a potential range of application as targeted drug delivery system in biomedical field.

  10. Nano zinc oxide-sodium alginate antibacterial cellulose fibres. (United States)

    Varaprasad, Kokkarachedu; Raghavendra, Gownolla Malegowd; Jayaramudu, Tippabattini; Seo, Jongchul


    In the present study, antibacterial cellulose fibres were successfully fabricated by a simple and cost-effective procedure by utilizing nano zinc oxide. The possible nano zinc oxide was successfully synthesized by precipitation technique and then impregnated effectively over cellulose fibres through sodium alginate matrix. XRD analysis revealed the 'rod-like' shape alignment of zinc oxide with an interplanar d-spacing of 0.246nm corresponding to the (101) planes of the hexagonal wurtzite structure. TEM analysis confirmed the nano dimension of the synthesized zinc oxide nanoparticles. The presence of nano zinc oxide over cellulose fibres was evident from the SEM-EDS experiments. FTIR and TGA studies exhibited their effective bonding interaction. The tensile stress-strain curves data indicated the feasibility of the fabricated fibres for longer duration utility without any significant damage or breakage. The antibacterial studies against Escherichia coli revealed the excellent bacterial devastation property. Further, it was observed that when all the parameters remained constant, the variation of sodium alginate concentration showed impact in devastating the E. coli. In overall, the fabricated nano zinc oxide-sodium alginate cellulose fibres can be effectively utilized as antibacterial fibres for biomedical applications.


    Directory of Open Access Journals (Sweden)

    Maria Dimarogona


    Full Text Available Enzymatic degradation of plant biomass has attracted intensive research interest for the production of economically viable biofuels. Here we present an overview of the recent findings on biocatalysts implicated in the oxidative cleavage of cellulose, including polysaccharide monooxygenases (PMOs or LPMOs which stands for lytic PMOs, cellobiose dehydrogenases (CDHs and members of carbohydrate-binding module family 33 (CBM33. PMOs, a novel class of enzymes previously termed GH61s, boost the efficiency of common cellulases resulting in increased hydrolysis yields while lowering the protein loading needed. They act on the crystalline part of cellulose by generating oxidized and non-oxidized chain ends. An external electron donor is required for boosting the activity of PMOs. We discuss recent findings concerning their mechanism of action and identify issues and questions to be addressed in the future.

  12. Approche dynamique du premier harmonique pour la modélisation de convertisseurs AC-AC à étage intermédiaire continu. Application aux générateurs à induction (United States)

    Bacha, S.; Rognon, J. P.; Ferrieux, J. P.; Bendaas, M. L.


    In this paper, we present a modelling technique for power electronics converters with both DC and AC stages. This technique is based on a dynamical approach of the first harmonic method. The approach is first applied to an idealized converter and second is extended to a framework working under discontinuous conduction mode. At the end, comparative simulations are done to validate the continuous built model. Dans cet article, il est présenté une technique de modélisation de convertisseurs présentant à la fois des étages continus et alternatifs. Cette technique est basée sur une approche dynamique de la méthode du premier harmonique. La technique est tout d'abord appliquée à un convertisseur idéalisé pour être ensuite étendue à une structure travaillant en conclusion discontinue. En dernier lieu, des simulations viennent valider le modèle continu mis au point.

  13. CERN Technical Training 2003: Learning for the LHC! MAGNE-03 : Magnétisme pour l'Electrotechnique Phénomènes magnétiques, matériaux et applications - French version only

    CERN Multimedia


    MAGNE-03 est un nouveau cours dans le cadre du programme de l'Enseignement Technique 2003, qui s'adresse aux personnes souhaitant découvrir, améliorer ou remettre à niveau leurs connaissances en magnétisme. Recommandé par l'ancienne division LHC, le cours est donné au CERN par la société CEDRAT Technologies basée à Meylan (France, 38). La participation est ouverte à l'ensemble du personnel technique et scientifique nécessitant une formation en magnétisme dans le cadre de leurs activités professionnelles, courantes ou futures. En ayant organisé des sessions au CERN, une économie d'environ 800.- CHF par participant est réalisée par rapport aux frais nécessaires pour suivre la même formation sur leur site en Isère. MAGNE-03 s'intéresse, entre autres, au développement de la compréhension des phénomènes magnétiques et le "sens physique" appliqués à des produits industriels. Programme : Notions de base en électromagnétisme. Les aspects électrique et mécanique du magnétisme. Les ...

  14. CERN Technical Training 2003: Learning for the LHC! MAGNE-03 : Magnétisme pour l'Electrotechnique
    Phénomènes magnétiques, matériaux et applications. - French version only

    CERN Multimedia


    MAGNE-03 est un nouveau cours dans le cadre du programme de l'Enseignement Technique 2003, qui s'adresse aux personnes souhaitant découvrir, améliorer ou remettre à niveau leurs connaissances en magnétisme. Recommandé par l'ancienne division LHC, le cours est donné au CERN par la société CEDRAT Technologies basée à Meylan (France, 38). La participation est ouverte à l'ensemble du personnel technique et scientifique nécessitant une formation en magnétisme dans le cadre de leurs activités professionnelles, courantes ou futures. En ayant organisé des sessions au CERN, une économie d'environ 800.- CHF par participant est réalisée par rapport aux frais nécessaires pour suivre la même formation sur leur site en Isère. MAGNE-03 s'intéresse, entre autres, au développement de la compréhension des phénomènes magnétiques et le "sens physique" appliqués à des produits industriels. Programme : Notions de base en électromagnétisme. Les aspects électrique et mécanique du magnétisme. Les ...

  15. Cellulose nanocrystals reinforced foamed nitrile rubber nanocomposites. (United States)

    Chen, Yukun; Zhang, Yuanbing; Xu, Chuanhui; Cao, Xiaodong


    Research on foamed nitrile rubber (NBR)/cellulose nanocrystals (CNs) nanocomposites is rarely found in the literatures. In this paper, CNs suspension and NBR latex was mixed to prepared the foamed NBR/CNs nanocomposites. We found that the CNs mainly located in the cell walls, effectively reinforcing the foamed NBR. The strong interaction between the CNs and NBR matrix restricted the mobility of NBR chains surrounding the CNs, hence increasing the crosslink density of the NBR matrix. CNs exhibited excellent reinforcement on the foamed NBR: a remarkable increase nearly 76% in the tensile strength of the foamed nanocomposites was achieved with a load of only 15 phr CNs. Enhanced mechanical properties make the foamed NBR/CNs nanocomposites a promising damping material for industrial applications with a potential to reduce the petroleum consumption.

  16. High-sensitivity gamma spectroscopy for extended sources. Application to activity measurements on the human body, on glass, and on soil; Spectrographie gamma a grande sensibilite pour sources etendues. Application a la mesure de l'activite du corps humain, du verre et du sol

    Energy Technology Data Exchange (ETDEWEB)

    Jouve, B


    The measurement and location by gamma spectroscopy of human body internal contaminations at maximum permissible levels, and, in certain cases, at lower activities such as that due to {sup 40}K was investigated. The characteristics of the high-sensitivity apparatus used are given, and several assemblies using large-volume NaI(Tl) scintillators are described. The relatively light shielding required for natural radioactivity permitted construction of mobile assembly. Conditions of use are described, and the results are given. All gamma emitting elements were measured in 15 min at levels lower than the tolerance dose. Gamma spectroscopy was also used to determine fission products in the earth and to study radioactive elements in the presence of other emitters. (author) [French] La spectrographie gamma du corps humain permet la mesure et la localisation des contaminations internes au niveau des doses de tolerance et, dans certains cas, celle d'activites plus faibles comme la radioactivite naturelle due principalement au potassium 40. Les caracteristiques des appareils a grande sensibilite permettant ces mesures sont exposees et on decrit plusieurs realisations originales utilisant un scintillateur NaI(Tl) de grand volume. L'epaisseur du blindage a ete limitee a 5 cm de plomb, ainsi, pour une protection suffisante contre les rayonnements ambiants, les appareils sont relativement legers et l'une des realisations a pu etre installee dans un laboratoire mobile. Les conditions d'utilisation (mouvement propre, etalonnage) et les resultats obtenus sont donnes; tous les radioelements emetteurs gamma sont mesurables en 15 minutes a un niveau inferieur a la dose de tolerance. On presente enfin des applications a la spectrographie gamma d'echantillons volumineux (poudres ou liquides) et de tres faible activite: elles interessent des domaines tres varies comme, par exemple, la geophysique (etude des retombees radioactives) ou l'industrie chimique

  17. Une interface gestuelle pour l'apprentissage de la rythmique


    Kamp, Jean-François; Ménier, Gildas; Gibet, Sylvie


    Session "Atelier IHMA"; National audience; Le système pédagogique d'apprentissage de la rythmique que nous présentons dans ce papier relève à la fois de l'interaction gestuelle et de l'instrument de musique virtuel. Il utilise le gant de données CyberGlove® comme modalité en entrée pour piloter une application musicale d'enregistrement, de production et de modification de sons de percussion. Le papier présente les principes de base du système qui consiste à générer des sons de percussion par ...

  18. Quantitatively pouring draft beer dispenser; Teiryo chushutsu nama beer dispenser

    Energy Technology Data Exchange (ETDEWEB)



    Suppressing bubble generation and quantitatively pouring more stably were the large problem in draft beer or sparking liquor vending. Therefore, bubbling mechanism in draft beer was analyzed, and pouring valve and beer dispensing system were optimized to have developed a beer dispenser generating little bubbles when dispensing. Its major features are as follows: (1) a valve was developed that branches liquid and bubbles without disturbing the beer flow, thus realizing stable pouring; (2) a beer mug tray drive was developed that prevents after-drips of bubbles from entering into another mug, thus realizing stable pouring; (3) the button operated rinsing function and the pouring valve removing and attaching structure facilitate washing work; and (4) the additional pouring function and the copying function facilitate setting of the dispensing volume. (translated by NEDO)

  19. Effects of reaction conditions on cellulose structures synthesized in vitro by bacterial cellulose synthases. (United States)

    Penttilä, Paavo A; Sugiyama, Junji; Imai, Tomoya


    Cellulose was synthesized by cellulose synthases extracted from the Komagataeibacter xylinus (formerly known as Gluconacetobacter xylinus). The effects of temperature and centrifugation of the reaction solution on the synthesis products were investigated. Cellulose with number-average degree of polymerization (DPn) roughly in the range 60-80 and cellulose II crystal structure was produced under all conditions. The amount of cellulose varied with temperature and centrifugation, and the centrifugation at 2000 × g also slightly reduced the DPn. Cellulose production was maximal around the temperature 35 °C and without centrifugation. At higher temperatures and during centrifugation at 2000 × g the proteins started to denature, causing differences also in the morphology of the cellulosic aggregates, as seen with electron microscopy. These observations serve as a basis for discussions about the factors affecting the structure formation and chain length of in vitro synthesized cellulose.

  20. Assessment of solvents for cellulose dissolution. (United States)

    Ghasemi, Mohammad; Tsianou, Marina; Alexandridis, Paschalis


    A necessary step in the processing of biomass is the pretreatment and dissolution of cellulose. A good solvent for cellulose involves high diffusivity, aggressiveness in decrystallization, and capability of disassociating the cellulose chains. However, it is not clear which of these factors and under what conditions should be improved in order to obtain a more effective solvent. To this end, a newly-developed phenomenological model has been applied to assess the controlling mechanism of cellulose dissolution. Among the findings, the cellulose fibers remain crystalline almost to the end of the dissolution process for decrystallization-controlled kinetics. In such solvents, decreasing the fiber crystallinity, e.g., via pretreatment, would result in a considerable increase in the dissolution rate. Such insights improve the understanding of cellulose dissolution and facilitate the selection of more efficient solvents and processing conditions for biomass. Specific examples of solvents are provided where dissolution is limited due to decrystallization or disentanglement.

  1. Controlling the structure and rheology of TEMPO-oxidized cellulose in zinc chloride aqueous suspensions for fabricating advanced nanopaper (United States)

    Wang, Sha; Zhang, Xin; Hu, Liangbing; Briber, Robert; Wang, Howard; Zhong, Linxin

    Due to its abundance, low-cost, biocompatibility and renewability, cellulose has become an attractive candidate as a functional material for various advanced applications. A key to novel applications is the control of the structure and rheology of suspensions of fibrous cellulose. Among many different approaches of preparing cellulose suspensions, zinc chloride addition to aqueous suspensions is regarded an effective practice. In this study, effects of ZnCl2 concentration on TEMPO-oxidized cellulose (TOC) nanofiber suspensions have been investigated. Highly-transparent cellulose nanofiber suspension can be rapidly obtained by dissolving TOC in 65 wt.% zinc chloride aqueous solutions at room temperature, whereas a transparent zinc ion cross-linked TOC gel could be obtained with zinc chloride concentration as low as 10 wt. %. The structural and rheological characteristics of TOC/ZnCl2 suspensions have been measured to correlate to the performance of thetransparent and flexible nanocellulose paper subsequently produced via vacuum filtration or wet-casting processes.

  2. Increasing cellulose production and transgenic plant growth in forest tree species

    Institute of Scientific and Technical Information of China (English)

    TANG Wei; Aaron Nelson; Emmanuel Johnson


    effect of the antisense transgene expression on lignin content, cellulose accumulation, and loblolly pine biomass; and (4) select fast growth and high cellulose accumulation transgenic loblolly pine lines for future commercial application.

  3. Structure of the Cellulose Synthase Complex of Gluconacetobacter hansenii at 23.4 A Resolution.

    Directory of Open Access Journals (Sweden)

    Juan Du

    Full Text Available Bacterial crystalline cellulose is used in biomedical and industrial applications, but the molecular mechanisms of synthesis are unclear. Unlike most bacteria, which make non-crystalline cellulose, Gluconacetobacter hansenii extrudes profuse amounts of crystalline cellulose. Its cellulose synthase (AcsA exists as a complex with accessory protein AcsB, forming a 'terminal complex' (TC that has been visualized by freeze-fracture TEM at the base of ribbons of crystalline cellulose. The catalytic AcsAB complex is embedded in the cytoplasmic membrane. The C-terminal portion of AcsC is predicted to form a translocation channel in the outer membrane, with the rest of AcsC possibly interacting with AcsD in the periplasm. It is thus believed that synthesis from an organized array of TCs coordinated with extrusion by AcsC and AcsD enable this bacterium to make crystalline cellulose. The only structural data that exist for this system are the above mentioned freeze-fracture TEM images, fluorescence microscopy images revealing that TCs align in a row, a crystal structure of AcsD bound to cellopentaose, and a crystal structure of PilZ domain of AcsA. Here we advance our understanding of the structural basis for crystalline cellulose production by bacterial cellulose synthase by determining a negative stain structure resolved to 23.4 Å for highly purified AcsAB complex that catalyzed incorporation of UDP-glucose into β-1,4-glucan chains, and responded to the presence of allosteric activator cyclic diguanylate. Although the AcsAB complex was functional in vitro, the synthesized cellulose was not visible in TEM. The negative stain structure revealed that AcsAB is very similar to that of the BcsAB synthase of Rhodobacter sphaeroides, a non-crystalline cellulose producing bacterium. The results indicate that the crystalline cellulose producing and non-crystalline cellulose producing bacteria share conserved catalytic and membrane translocation components, and

  4. Structure of the Cellulose Synthase Complex of Gluconacetobacter hansenii at 23.4 Å Resolution (United States)

    Du, Juan; Vepachedu, Venkata; Cho, Sung Hyun; Kumar, Manish; Nixon, B. Tracy


    Bacterial crystalline cellulose is used in biomedical and industrial applications, but the molecular mechanisms of synthesis are unclear. Unlike most bacteria, which make non-crystalline cellulose, Gluconacetobacter hansenii extrudes profuse amounts of crystalline cellulose. Its cellulose synthase (AcsA) exists as a complex with accessory protein AcsB, forming a 'terminal complex' (TC) that has been visualized by freeze-fracture TEM at the base of ribbons of crystalline cellulose. The catalytic AcsAB complex is embedded in the cytoplasmic membrane. The C-terminal portion of AcsC is predicted to form a translocation channel in the outer membrane, with the rest of AcsC possibly interacting with AcsD in the periplasm. It is thus believed that synthesis from an organized array of TCs coordinated with extrusion by AcsC and AcsD enable this bacterium to make crystalline cellulose. The only structural data that exist for this system are the above mentioned freeze-fracture TEM images, fluorescence microscopy images revealing that TCs align in a row, a crystal structure of AcsD bound to cellopentaose, and a crystal structure of PilZ domain of AcsA. Here we advance our understanding of the structural basis for crystalline cellulose production by bacterial cellulose synthase by determining a negative stain structure resolved to 23.4 Å for highly purified AcsAB complex that catalyzed incorporation of UDP-glucose into β-1,4-glucan chains, and responded to the presence of allosteric activator cyclic diguanylate. Although the AcsAB complex was functional in vitro, the synthesized cellulose was not visible in TEM. The negative stain structure revealed that AcsAB is very similar to that of the BcsAB synthase of Rhodobacter sphaeroides, a non-crystalline cellulose producing bacterium. The results indicate that the crystalline cellulose producing and non-crystalline cellulose producing bacteria share conserved catalytic and membrane translocation components, and support the

  5. Composites organiques-inorganiques pour la substitution et la réparation osseuse : concepts, premiers résultats et potentialités Organic-inorganic composites for bone substitute and bone repair applications: concepts, first results and potentialities

    Directory of Open Access Journals (Sweden)

    Peroglio Marianna


    Full Text Available Ce document présente un très bref aperçu de l'intérêt des matériaux composites organique – inorganique pour la substitution et la réparation osseuse. Deux types de composites sont présentés. Dans une première partie, des matériaux poreux en céramique ou bio-verre élaborés par la technologie des poudres sont imprégnés par un polymère. Cette imprégnation se traduit par une forte augmentation de l'énergie à la rupture du squelette céramique, permettant de limiter le risque de rupture fragile. L'augmentation des propriétés mécaniques des substituts osseux céramiques par une phase polymère peut être mise en regard des mécanismes de renforcement présents dans l'os et du rôle du collagène sur la ténacité de celui-ci. Dans une deuxième partie, des composites denses sont élaborés par des technologies de plasturgie, qui permettent de réaliser des produits de formes complexes. Les phases polymères et céramiques sont ici choisies pour leurs caractères respectifs résorbable et ostéo-inducteur. Ces composites permettent la création rapide d'hydroxyapatite à leur surface et accélèrent la guérison osseuse. A terme, ils sont résorbés. Ces deux exemples démontrent les potentialités de tels multi-matériaux architecturés pour la réalisation de substituts osseux plus résistants mécaniquement et apportant de nouvelles fonctionnalités, ainsi que pour la production de produits d'ostéosynthèse favorisant les processus de guérison osseuse. Here we show a brief outline of organic-inorganic composites for bone substitute and bone repair applications. Two types of composites are presented. In a first strategy, porous ceramics and bioactive glasses processed by sintering methods are impregnated by a polymer. The strong improvement of the mechanical properties of the ceramic scaffolds by a polymer phase can be linked to the one present in bone with the role of collagen on bone toughness. In a second strategy, a

  6. Cellulose nanomaterials review: structure, properties and nanocomposites


    Moon, Robert J.; Martini, Ashlie; Nairn, John; Simonsen, John; Youngblood, Jeffrey


    This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them. It summarizes cellulose nanoparticles in terms of particle morphology, crystal structure, and properties. Also described are the self-assembly and rheological properties of cellulose nanoparticle suspensions. The methodology of composite processing and resulting properties are fully covered, with an emphasis on neat and high fraction...

  7. Drag Reduction of Bacterial Cellulose Suspensions

    Directory of Open Access Journals (Sweden)

    Satoshi Ogata


    Full Text Available Drag reduction due to bacterial cellulose suspensions with small environmental loading was investigated. Experiments were carried out by measuring the pressure drop in pipe flow. It was found that bacterial cellulose suspensions give rise to drag reduction in the turbulent flow range. We observed a maximum drag reduction ratio of 11% and found that it increased with the concentration of the bacterial cellulose suspension. However, the drag reduction effect decreased in the presence of mechanical shear.

  8. Size Effects of Nano-crystalline Cellulose

    Institute of Scientific and Technical Information of China (English)

    Guo Kang LI; Xiao Fang LI; Yong JIANG; Mei Zhen ZENG; En Yong DING


    Natural cellulose with the crystal form of cellulose Ⅰ, when treated with condensed lye(e.g. 18%NaOH), can change into new crystal form of cellulose Ⅱ. But the nano-crystallinecellulose(NCC) can do it when only treated with dilute lye (e.g. 1%NaOH) at room temperatureand even can dissolve into slightly concentrated lye (e.g. 4%NaOH).

  9. Alteration of in vivo cellulose ribbon assembly by carboxymethylcellulose and other cellulose derivatives



    In vivo cellulose ribbon assembly by the Gram-negative bacterium Acetobacter xylinum can be altered by incubation in carboxymethylcellulose (CMC), a negatively charged water-soluble cellulose derivative, and also by incubation in a variety of neutral, water-soluble cellulose derivatives. In the presence of all of these substituted celluloses, normal fasciation of microfibril bundles to form the typical twisting ribbon is prevented. Alteration of ribbon assembly is most extensive in the presen...

  10. Alexa Fluor-labeled Fluorescent Cellulose Nanocrystals for Bioimaging Solid Cellulose in Spatially Structured Microenvironments

    Energy Technology Data Exchange (ETDEWEB)

    Grate, Jay W.; Mo, Kai-For; Shin, Yongsoon; Vasdekis, Andreas; Warner, Marvin G.; Kelly, Ryan T.; Orr, Galya; Hu, Dehong; Dehoff, Karl J.; Brockman, Fred J.; Wilkins, Michael J.


    Cellulose nanocrystal materials have been labeled with modern Alexa Fluor dyes in a process that first links the dye to a cyanuric chloride molecule. Subsequent reaction with cellulose nanocrystals provides dyed solid microcrystalline cellulose material that can be used for bioimaging and suitable for deposition in films and spatially structured microenvironments. It is demonstrated with single molecular fluorescence microscopy that these films are subject to hydrolysis by cellulose enzymes.

  11. Empirical Calibration for Dolomite Stoichiometry Calculation: Application on Triassic Muschelkalk- Lettenkohle Carbonates (French Jura Calibration empirique pour le calcul de la stoechiométrie de la dolomite : application aux carbonates triasiques du Muschelkalk-Lettenkohle (Jura français

    Directory of Open Access Journals (Sweden)

    Turpin M.


    Full Text Available This study concerns an approach for dolomite quantification and stoichiometry calculation by using X-ray diffractometry coupled with cell and Rietveld refinements and equipped with a newly substantial database of dolomite composition. A greater accuracy and precision are obtained for quantifying dolomite as well as other mineral phases and calculating dolomite stoichiometry compared to the classical “Lumsden line” and previous methods. The applicability of this approach is verified on dolomite reference material (Eugui and on Triassic (Upper Muschelkalk-Lettenkohle carbonates from the French Jura. The approach shown here is applicable to bulk dolostones as well as to specific dolomite cements and was combined with petrographical and isotopic analyses. Upper Muschelkalk dolomites were formed during burial dolomitization under fluids characterized by increased temperature and variable isotopic composition through burial. This is clear from their Ca content in dolomites which gradually approaches an ideal stoichiometry (from 53.16% to 51.19% through increasing dolomitization. Lettenkohle dolostones consist of near-ideal stoichiometric (51.06%Ca and well-ordered dolomites associated with anhydrite relicts. They originated through both sabkha and burial dolomitization. This contribution gives an improved method for the characterization of different dolomite types and their distinct traits in sedimentary rocks, which allows a better evaluation of their reservoir potential. Cette étude propose une approche pour la quantification de la dolomite et le calcul de sa stoechiométrie grâce à l’utilisation de la diffraction des rayons X couplée aux affinements de maille et de Rietveld et complétée par de nombreuses données issues de la littérature. Elle permet d’obtenir une meilleure justesse et précision pour la quantification de la dolomite (et des autres phases minérales ainsi que pour le calcul de sa stoechiométrie par rapport à l

  12. POSS-Modified Cellulose for Improved Biopolymer Performance (United States)


    E7(/(3+21(180%(5 ,QFOXGHDUHDFRGH 09-30-2011 Final Technical 07-01-2010 to 06-30-2011 POSS-Modified Cellulose for Improved Biopolymer ... Biopolymer Performance” (AFOSR-DURIP Grant #FA9550-10-1-0323) DATE: September 30, 2011 Summary Funding for this project was used to purchase...promise in biomedical applications, such as medical implants, surgical sutures, and tissue scaffolding . To improve the low impact strength, poor

  13. Cellulose/polyvinyl alcohol-based hydrogels for reconfigurable lens (United States)

    Jayaramudu, T.; Ko, Hyun-U.; Gao, Xiaoyuan; Li, Yaguang; Kim, Sang Youn; Kim, Jaehwan


    Electroactive hydrogels are attractive for soft robotics and reconfigurable lens applications. Here we describe the design and fabrication of cellulose-poly vinyl alcohol based hydrogels. The fabricated hydrogels were confirmed by Fourier transformer spectroscopy, swelling studies, thermal analysis, surface morphology of fabricated hydrogel was study by using scanning electron microscopy. The effect of poly vinyl alcohol concentration on the optical and electrical behavior of hydrogels was studied.

  14. Cytocompatible cellulose hydrogels containing trace lignin. (United States)

    Nakasone, Kazuki; Kobayashi, Takaomi


    Sugarcane bagasse was used as a cellulose resource to prepare transparent and flexible cellulose hydrogel films. On the purification process from bagasse to cellulose, the effect of lignin residues in the cellulose was examined for the properties and cytocompatibility of the resultant hydrogel films. The cellulose was dissolved in lithium chloride/N,N-dimethylacetamide solution and converted to hydrogel films by phase inversion. In the purification process, sodium hydroxide (NaOH) treatment time was changed from 1 to 12h. This resulted in cellulose hydrogel films having small amounts of lignin from 1.62 to 0.68%. The remaining lignin greatly affected hydrogel properties. Water content of the hydrogel films was increased from 1153 to 1525% with a decrease of lignin content. Moreover, lower lignin content caused weakening of tensile strength from 0.80 to 0.43N/mm(2) and elongation from 45.2 to 26.5%. Also, similar tendency was observed in viscoelastic behavior of the cellulose hydrogel films. Evidence was shown that the lignin residue was effective for the high strength of the hydrogel films. In addition, scanning probe microscopy in the morphological observation was suggested that the trace lignin in the cellulose hydrogel affected the cellulose fiber aggregation in the hydrogel network. The trace of lignin in the hydrogels also influenced fibroblast cell culture on the hydrogel films. The hydrogel film containing 1.68% lignin showed better fibroblast compatibility as compared to cell culture polystyrene dish used as reference.

  15. Carboxymethylation of Cellulose by Microwave irradiation

    Institute of Scientific and Technical Information of China (English)

    YE Jun; XIONG Jian; SU Yingzhi; XIAO Ping


    @@ Cellulose may be readily converted into ethers involving primary and secondary alcohol groups in each monomer unit and the glycosidic bonds. However, these reactions are rather more complicated than with simple substances, because the stereochemistry of the cellulose molecule is such that the vast majority of its hydroxyl groups form intra-chain hydrogen bonds or inter-chain hydrogen bonds with contiguous molecules. Carboxymethylcellulose (CMC) has played an important part in the commercial uses of cellulose derivatives. CMC becomes alkali and water soluble. The polarity can, in fact, be increased by introduction of ionizing groups, ie carboxymethyl group. CMC is generally produced by the reaction of alkali cellulose with chloroacetic acid.

  16. Chemo-catalytic valorization of cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Palkovits, R. [RWTH Aachen Univ. (Germany). Inst. fuer Technische und Makromolekulare Chemie


    Cellulose can be utilized as carbon source for the production of novel platform molecules as well as fuel motifs. Promising transformation strategies cover the hydrolytic hydrogenation or hydrogenolysis of cellulose to sugar alcohols, the hydrolysis of cellulose to glucose followed by dehydration to 5-hydroxymethylfurfural or levulinic acid and the further hydrogenation of levulinic acid to {gamma}-valerolactone. Main challenges result from the high degree of functionalization of cellulosic feedstocks. In line, processes are carried out in liquid phase utilizing rather polar solvents and aiming for a tailored defunctionalisation of these oxygen rich compounds. Consequently, such transformations require novel strategies concerning the development of suitable catalysts and appropriate process concepts. (orig.)

  17. [Supramolecular reorganizations in cellulose during hydration]. (United States)

    Grunin, Iu B; Grunin, L Iu; Talantsev, V I; Nikol'skaia, E A; Masas, D S


    The analysis of modern ideas about the structural organization of the cellulose microfibrils is carried out. The mechanism of the formation of additional capillary-porous system of cellulose under moistening is offered. It is established that when the moisture content of cellulose reaches 8-10%, the filling of its micropores occurs with a simultaneous increase in their cross sizes, a specific surface and reduction in the degree of crystallinity of specimens. Within the proposed model of microfibril construction the parameters of supramolecular structure and capillary-porous system of cotton cellulose are determined.

  18. Application de la diffraction des rayons X in situ à haute température pour l'identification d'une nouvelle phase lors de l'oxydation à 900circC de l'acier 304 (United States)

    Riffard, F.; Buscail, H.; Caudron, E.; Cueff, R.; Issartel, C.; El Messki, S.; Perrier, S.


    Une nouvelle interprétation du comportement atypique couramment appelé "breakaway" observé lors de l'oxydation à haute température d'alliages chromino-formeurs est proposée grâce à l'utilisation de la diffraction des rayons X in situ à haute température. L'acier chromino-formeur AISI 304 doit établir une couche d'oxyde superficielle généralement dense et majoritairement, constituée de chromine, dont la vitesse de croissance est lente, afin d'assurer sa protection contre la corrosion à haute température. Cette faible vitesse de croissance de la couche d'oxyde est effectivement observée à 1000circC. Elle serait favorisée par l'établissement d'une couche de chromine induite par la présence d'une sous-couche continue de silice à l'interface interne. Cette dernière limiterait la diffusion du fer. Le phénomène du "breakaway" est observé à la température de 900circC après 40 heures d'oxydation. Ce phénomène serait lié à la croissance initiale d'oxydes contenant du fer. L'oxyde Fe{7}SiO{10, }a été identifié{ }pour la première fois grâce à la technique de diffraction des rayons X in situ à haute température. Cet oxyde semble piéger le silicium dans la couche d'oxyde, empêchant son accumulation à l'interface interne et la formation d'une couche continue de silice.

  19. Simultaneous cellulose conversion and hydrogen production assisted by cellulose decomposition under UV-light photocatalysis. (United States)

    Zhang, Guan; Ni, Chengsheng; Huang, Xiubing; Welgamage, Aakash; Lawton, Linda A; Robertson, Peter K J; Irvine, John T S


    Photocatalytic conversion of cellulose to sugars and carbon dioxide with simultaneous production of hydrogen assisted by cellulose decomposition under UV or solar light irradiation was achieved upon immobilization of cellulose onto a TiO2 photocatalyst. This approach enables production of hydrogen from water without using valuable sacrificial agents, and provides the possibility for recovering sugars as liquid fuels.

  20. Liquid crystalline solutions of cellulose in phosphoric acid for preparing cellulose yarns

    NARCIS (Netherlands)

    Boerstoel, H.


    The presen thesis describes a new process for manufacturing high tenacity and high modulus cellulose yarns. A new direct solvent for cellulose has been discovered, leading to liquid crystalline solutions. This new solvent, superphosphoric acid, rapidly dissolves cellulose. These liquid crystalline s

  1. Dispersion of cellulose nanofibers in biopolymer based nanocomposites (United States)

    Wang, Bei

    The focus of this work was to understand the fundamental dispersion mechanism of cellulose based nanofibers in bionanocomposites. The cellulose nanofibers were extracted from soybean pod and hemp fibers by chemo-mechanical treatments. These are bundles of cellulose nanofibers with a diameter ranging between 50 to 100 nm and lengths of thousands of nanometers which results in very high aspect ratio. In combination with a suitable matrix polymer, cellulose nanofiber networks show considerable potential as an effective reinforcement for high quality specialty applications of bio-based nanocomposites. Cellulose fibrils have a high density of --OH groups on the surface, which have a tendency to form hydrogen bonds with adjacent fibrils, reducing interaction with the surrounding matrix. The use of nanofibers has been mostly restricted to water soluble polymers. This thesis is focused on synthesizing the nanocomposite using a solid phase matrix polypropylene (PP) or polyethylene (PE) by hot compression and poly (vinyl alcohol) (PVA) in an aqueous phase by film casting. The mechanical properties of nanofiber reinforced PVA film demonstrated a 4-5 fold increase in tensile strength, as compared to the untreated fiber-blend-PVA film. It is necessary to reduce the entanglement of the fibrils and improve their dispersion in the matrix by surface modification of fibers without deteriorating their reinforcing capability. Inverse gas chromatography (IGC) was used to explore how various surface treatments would change the dispersion component of surface energy and acid-base character of cellulose nanofibers and the effect of the incorporation of these modified nanofibers into a biopolymer matrix on the properties of their nano-composites. Poly (lactic acid) (PLA) and polyhydroxybutyrate (PHB) based nanocomposites using cellulose nanofibers were prepared by extrusion, injection molding and hot compression. The IGC results indicated that styrene maleic anhydride coated and ethylene

  2. Plasma-enhanced synthesis of green flame retardant cellulosic materials (United States)

    Totolin, Vladimir

    The natural fiber-containing fabrics and composites are more environmentally friendly, and are used in transportation (automobiles, aerospace), military applications, construction industries (ceiling paneling, partition boards), consumer products, etc. Therefore, the flammability characteristics of the composites based on polymers and natural fibers play an important role. This dissertation presents the development of plasma assisted - green flame retardant coatings for cellulosic substrates. The overall objective of this work was to generate durable flame retardant treatment on cellulosic materials. In the first approach sodium silicate layers were pre-deposited onto clean cotton substrates and cross linked using low pressure, non-equilibrium oxygen plasma. A statistical design of experiments was used to optimize the plasma parameters. The modified cotton samples were tested for flammability using an automatic 45° angle flammability test chamber. Aging tests were conducted to evaluate the coating resistance during the accelerated laundry technique. The samples revealed a high flame retardant behavior and good thermal stability proved by thermo-gravimetric analysis. In the second approach flame retardant cellulosic materials have been produced using a silicon dioxide (SiO2) network coating. SiO 2 network armor was prepared through hydrolysis and condensation of the precursor tetraethyl orthosilicate (TEOS), prior coating the substrates, and was cross linked on the surface of the substrates using atmospheric pressure plasma (APP) technique. Due to protection effects of the SiO2 network armor, the cellulosic based fibers exhibit enhanced thermal properties and improved flame retardancy. In the third approach, the TEOS/APP treatments were extended to linen fabrics. The thermal analysis showed a higher char content and a strong endothermic process of the treated samples compared with control ones, indicating a good thermal stability. Also, the surface analysis proved

  3. Highly Effective Electromagnetic Interference Shielding Materials based on Silver Nanowire/Cellulose Papers. (United States)

    Lee, Tae-Won; Lee, Sang-Eui; Jeong, Young Gyu


    We fabricated silver nanowire (AgNW)-coated cellulose papers with a hierarchical structure by an efficient and facile dip-coating process, and investigated their microstructures, electrical conductivity and electromagnetic interference (EMI) shielding effectiveness. SEM images confirm that AgNWs are coated dominantly on the paper surfaces, although they exist partially in the inner parts of the cellulose papers, which demonstrates that the AgNW density gradually decreases in thickness direction of the AgNW/cellulose papers. This result is supported by the anisotropic apparent electrical conductivity of the AgNW/cellulose papers depending on in-plane or thickness direction. Even for a AgNW/cellulose paper obtained by a single dip-coating cycle, the apparent electrical conductivity in the in-plane direction of 0.34 S/cm is achieved, which is far higher than the neat cellulose paper with ∼10(-11) S/cm. In addition, the apparent electrical conductivity of the papers in the in-plane direction increases significantly from 0.34 to 67.51 S/cm with increasing the number of dip-coating cycle. Moreover, although the AgNW/cellulose paper with 67.51 S/cm possesses 0.53 vol % AgNW only, it exhibits high EMI shielding performance of ∼48.6 dB at 1 GHz. This indicates that the cellulose paper structure is highly effective to form a conductive AgNW network. Overall, it can be concluded that the AgNW/cellulose papers with high flexibility and low density can be used as electrically conductive components and EMI shielding elements in advanced application areas.

  4. KINETIKA FERMENTASI SELULOSA MURNI OLEH Trichoderma reesi QM 9414 MENJADI GLUKOSA DAN PENERAPANNYA PADA JERAMI PADI BEBAS LIGNIN [Kinetics of Pure Cellulose Fermentation by Trichoderma Reesei QM 9414 to Glucose and Its Application of on Lignin Free Rice Straw

    Directory of Open Access Journals (Sweden)

    M Iyan Sofyan


    Full Text Available The objectives of this research were: 1 to determine aeration rate and substrate concentration of pure cellulose to produce maximum glucose by Trichoderma reesei QM 9414 at 30 oC, and agitation 150 rpm; 2 to study the kinetics of pure cellulose fermentation by Trichoderma reesei QM 9414 to glucose and its implication upon fermentation of the lignin free rice straw. The experiment was arranged in factorial randomized complete design in three times replication. Treatments consisted of three levels of aeration (1,00 vvm; 1,5 vvm; 2,0 vvm and three levels of substrate concentration (0,75 ; 1,00 ; 1,25 % w/v. The results showed that at the exponential phase the average specific growth of Trichoderma reesei QM 9414 was 0,05374 hour-1, the maximum glucose product concentration of pure cellulose was 0.1644 gL-1,and the oxygen transfer was 0,0328 mg L-1 hour-1. According to t-test, the kinetics of pure cellulose fermentation model just the same as the lignin free rice straw fermentation.The enzymes produced by Trichoderma reesei QM 9414 in pure cellulose fermentation media followed the Michaelis-Menten model. The enzyme kinetic parameters were the maximum growth rate was 37x10-3 hour-1 and Michaelis-Menten constant was ½ maximum μ =17,5x10-3 hour-1. The volumetric oxygen transfer (KLa using rice straw was 0,0337 mg.hour-1. The value of KLa could be used for conversion from bioreactor at laboratory scale to commercial scale design.

  5. Pyrolytic sugars from cellulosic biomass (United States)

    Kuzhiyil, Najeeb

    Sugars are the feedstocks for many promising advanced cellulosic biofuels. Traditional sugars derived from starch and sugar crops are limited in their availability. In principle, more plentiful supply of sugars can be obtained from depolymerization of cellulose, the most abundant form of biomass in the world. Breaking the glycosidic bonds between the pyranose rings in the cellulose chain to liberate glucose has usually been pursued by enzymatic hydrolysis although a purely thermal depolymerization route to sugars is also possible. Fast pyrolysis of pure cellulose yields primarily levoglucosan, an anhydrosugar that can be hydrolyzed to glucose. However, naturally occurring alkali and alkaline earth metals (AAEM) in biomass are strongly catalytic toward ring-breaking reactions that favor formation of light oxygenates over anhydrosugars. Removing the AAEM by washing was shown to be effective in increasing the yield of anhydrosugars; but this process involves removal of large amount of water from biomass that renders it energy intensive and thereby impractical. In this work passivation of the AAEM (making them less active or inactive) using mineral acid infusion was explored that will increase the yield of anhydrosugars from fast pyrolysis of biomass. Mineral acid infusion was tried by previous researchers, but the possibility of chemical reactions between infused acid and AAEM in the biomass appears to have been overlooked, possibly because metal cations might be expected to already be substantially complexed to chlorine or other strong anions that are found in biomass. Likewise, it appears that previous researchers assumed that as long as AAEM cations were in the biomass, they would be catalytically active regardless of the nature of their complexion with anions. On the contrary, we hypothesized that AAEM can be converted to inactive or less active salts using mineral acids. Various biomass feedstocks were infused with mineral (hydrochloric, nitric, sulfuric and

  6. Crosslinked cellulose thin film composite nanofiltration membranes with zero salt rejection

    KAUST Repository

    Puspasari, Tiara


    We report a new synthetic route of fabricating regenerated cellulose nanofiltration membranes. The membranes are composite membranes with a thin selective layer of cellulose, which was prepared by regeneration of trimethylsilyl cellulose (a hydrophobic cellulose derivative) film followed by crosslinking. Filtration experiments using mixtures of sugar and sodium chloride showed that solutes above 300 Da were highly rejected whereas practically no rejection was observed for NaCl. This is a big advantage for a complete desalination as the existing commercial nanofiltration membranes typically exhibit NaCl rejection in the range of 30–60%. Membranes with zero NaCl rejection are required for recovery and purification applications in food, chemical and pharmaceutical industry.

  7. Fabrication of Cellulose Nanofiber/AlOOH Aerogel for Flame Retardant and Thermal Insulation

    Directory of Open Access Journals (Sweden)

    Bitao Fan


    Full Text Available Cellulose nanofiber/AlOOH aerogel for flame retardant and thermal insulation was successfully prepared through a hydrothermal method. Their flame retardant and thermal insulation properties were investigated. The morphology image of the cellulose nanofiber/AlOOH exhibited spherical AlOOH with an average diameter of 0.5 μm that was wrapped by cellulose nanofiber or adhered to them. Cellulose nanofiber/AlOOH composite aerogels exhibited excellent flame retardant and thermal insulation properties through the flammability test, which indicated that the as-prepared composite aerogels would have a promising future in the application of some important areas such as protection of lightweight construction materials.

  8. Modified cellulose synthase gene from Arabidopsis thaliana confers herbicide resistance to plants (United States)

    Somerville, Chris R.; Scheible, Wolf


    Cellulose synthase ("CS"), a key enzyme in the biosynthesis of cellulose in plants is inhibited by herbicides comprising thiazolidinones such as 5-tert-butyl-carbamoyloxy-3-(3-trifluromethyl)phenyl-4-thiazolidinone (TZ), isoxaben and 2,6-dichlorobenzonitrile (DCB). Two mutant genes encoding isoxaben and TZ-resistant cellulose synthase have been isolated from isoxaben and TZ-resistant Arabidopsis thaliana mutants. When compared with the gene coding for isoxaben or TZ-sensitive cellulose synthase, one of the resistant CS genes contains a point mutation, wherein glycine residue 998 is replaced by an aspartic acid. The other resistant mutation is due to a threonine to isoleucine change at amino acid residue 942. The mutant CS gene can be used to impart herbicide resistance to a plant; thereby permitting the utilization of the herbicide as a single application at a concentration which ensures the complete or substantially complete killing of weeds, while leaving the transgenic crop plant essentially undamaged.

  9. Ionic Liquids — Promising but Challenging Solvents for Homogeneous Derivatization of Cellulose

    Directory of Open Access Journals (Sweden)

    Pedro Fardim


    Full Text Available In the past decade, ionic liquids (ILs have received enormous interest as solvents for cellulose. They have been studied intensively for fractionation and biorefining of lignocellulosic biomass, for dissolution of the polysaccharide, for preparation of cellulosic fibers, and in particular as reaction media for the homogeneous preparation of highly engineered polysaccharide derivatives. ILs show great potential for application on a commercial scale regarding recyclability, high dissolution power, and their broad structural diversity. However, a critical analysis reveals that these promising features are combined with serious drawbacks that need to be addressed in order to utilize ILs for the efficient synthesis of cellulose derivatives. This review presents a comprehensive overview about chemical modification of cellulose in ILs. Difficulties encountered thereby are discussed critically and current as well as future developments in this field of polysaccharide research are outlined.

  10. An improved X-ray diffraction method for cellulose crystallinity measurement. (United States)

    Ju, Xiaohui; Bowden, Mark; Brown, Elvie E; Zhang, Xiao


    We show in this work a modified X-ray diffraction method to determine cellulose crystallinity index (CrI). Nanocrystalline cellulose (NCC) derived from bleached wood pulp was used as a model substrate. Rietveld refinement was applied with consideration of March-Dollase preferred orientation at the (001) plane. In contrast to most previous methods, three distinct amorphous peaks identified from new model samples which used to calculate CrI. A 2 theta range from 10° to 75° was found to be more suitable to determine CrI and crystallite structural parameters such as d-spacing and crystallite size. This method enables a more reliable measurement of CrI of cellulose and may be applicable to other types of cellulose polymorphs.

  11. Transformation a Echelle Fixe et Groupe de Renormalisation pour les Objets Fractals et Multifractals (United States)

    Tremblay, Real

    Dans un premier temps, la description mathematique des fractals et des multifractais est resumee. Une description de quelques-uns des principaux systemes ou apparaissent des spectres d'exposants multifractals est presentee. L'accent est mis sur deux archetypes, le modele de percolation et le modele de rupture dielectrique. Un modele original de cascade multifractale avec interactions inspire des modeles phenomenologiques de la turbulence est presente et son spectre d'exposants calcule analytiquement. Ce travail elargit la classe de modeles pour lesquels on connait le spectre d'exposants exactement. Dans la seconde partie, on trouve une analyse critique de la transformation a echelle fixe. Sont discutees plus particulierement les proprietes que doivent posseder les diagrammes de base pour obtenir une transformation invariante d'echelle. Les differentes hypotheses arbitraires de la theorie sont mises en evidence. L'une de ces hypotheses concerne le traitement auto-coherent des conditions aux frontieres. Considerant cette hypothese comme valable, la theorie utilise la distribution de trous dans un ensemble de Cantor aleatoire. Un calcul exact de cette distribution est donne ici. Enfin, en troisieme et dernier lieu, on retrouve une analyse exhaustive du probleme du crossover dans le modele de percolation avec une resistance non-nulle pour les liens normalement isolants. A l'aide du groupe de renormalisation de Migdal-Kadanoff, on montre qu'il existe un seul exposant de crossover et une seule longueur de coherence. D'autres longueurs de correlation peuvent etre definies, mais elles demeurent dans un rapport fixe le long des axes propres du groupe de renormalisation. La multifractalite est donc, pour ce modele et ceux qui peuvent etre formules de facon analogue, compatible avec l'existence d'une seule longueur de coherence. Ces resultats sont d'application directe pour les proprietes electriques des milieux desordonnes.

  12. La correspondance de Langlands locale p-adique pour GL_2(Q_p)

    CERN Document Server

    Berger, Laurent


    La correspondance de Langlands locale p-adique pour GL_2(Q_p) est une bijection entre certaines representations de dimension 2 de Gal(Q_p^bar/Q_p) et certaines representations de GL_2(Q_p). Cette bijection peut en fait etre construite en utilisant la theorie des (phi,Gamma)-modules et des resultats d'analyse p-adique. On deduit alors des proprietes de cette construction quelques applications interessantes en arithmetique.

  13. A statistical treatment of bioassay pour fractions (United States)

    Barengoltz, Jack; Hughes, David

    A bioassay is a method for estimating the number of bacterial spores on a spacecraft surface for the purpose of demonstrating compliance with planetary protection (PP) requirements (Ref. 1). The details of the process may be seen in the appropriate PP document (e.g., for NASA, Ref. 2). In general, the surface is mechanically sampled with a damp sterile swab or wipe. The completion of the process is colony formation in a growth medium in a plate (Petri dish); the colonies are counted. Consider a set of samples from randomly selected, known areas of one spacecraft surface, for simplicity. One may calculate the mean and standard deviation of the bioburden density, which is the ratio of counts to area sampled. The standard deviation represents an estimate of the variation from place to place of the true bioburden density commingled with the precision of the individual sample counts. The accuracy of individual sample results depends on the equipment used, the collection method, and the culturing method. One aspect that greatly influences the result is the pour fraction, which is the quantity of fluid added to the plates divided by the total fluid used in extracting spores from the sampling equipment. In an analysis of a single sample’s counts due to the pour fraction, one seeks to answer the question: What is the probability that if a certain number of spores are counted with a known pour fraction, that there are an additional number of spores in the part of the rinse not poured. This is given for specific values by the binomial distribution density, where detection (of culturable spores) is success and the probability of success is the pour fraction. A special summation over the binomial distribution, equivalent to adding for all possible values of the true total number of spores, is performed. This distribution when normalized will almost yield the desired quantity. It is the probability that the additional number of spores does not exceed a certain value. Of course

  14. Idealized powder diffraction patterns for cellulose polymorphs (United States)

    Cellulose samples are routinely analyzed by X-ray diffraction to determine their crystal type (polymorph) and crystallinity. However, the connection is seldom made between those efforts and the crystal structures of cellulose that have been determined with synchrotron X-radiation and neutron diffrac...

  15. 21 CFR 172.870 - Hydroxypropyl cellulose. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Hydroxypropyl cellulose. 172.870 Section 172.870... CONSUMPTION Multipurpose Additives § 172.870 Hydroxypropyl cellulose. The food additive hydroxypropyl... anhydrous basis, not more than 4.6 hydroxypropyl groups per anhydroglucose unit. The additive has a...

  16. Conformational studies of cellulosic fragments by DFT (United States)

    The study of cellulosic fragments by DFTr is a continuation of our efforts to produce quality structural data that will be valuable to those working in the field of cellulose structure and enzymatic degradation. Using a reduced basis set and density functional DFTr (B3LYP), optimization of cellulosi...

  17. Diffraction from nonperiodic models of cellulose crystals (United States)

    Powder and fiber diffraction patterns were calculated for model cellulose crystallites with chains 20 glucose units long. Model sizes ranged from four chains to 169 chains, based on cellulose I' coordinates, and were subjected to various combinations of energy minimization and molecular dynamics (M...

  18. A novel method for preparing microfibrillated cellulose from bamboo fibers (United States)

    Dat Nguyen, Huu; Thanh Thuy Mai, Thi; Bich Nguyen, Ngoc; Duy Dang, Thanh; Loan Phung Le, My; Dang, Tan Tai; Tran, Van Man


    The bamboo fiber is a potential candidate for biomass and power source application. In this study, microfibrillated cellulose (MFC) is prepared from raw fibers of bamboo tree (Bambusa Blumeana J A & J H Schultes) by an alkali treatment at room temperature in association with a bleaching treatment followed by a sulfuric acid hydrolysis. Field-emission scanning electron microscopy (FESEM) images indicated that final products ranged from 20 to 40 nm in diameter. The chemical composition measurement and Fourier transform infrared (FTIR) spectroscopy showed that both hemicellulose and lignin are mostly removed in the MFC. The x-ray diffraction (XRD) results also show that MFC has crystallinity of more than 70%. The thermogravimetric analysis (TGA) curves revealed that cellulose microfibers have a two-step thermal decomposition behavior owing to the attachment of sulfated groups onto the cellulose surface in the hydrolysis process with sulfuric acid. The obtained MFCs may have potential applications in alternative power sources as biomass, in pharmaceutical and optical industries as additives, as well as in composite fields as a reinforcement phase.

  19. Hybrid HPMC nanocomposites containing bacterial cellulose nanocrystals and silver nanoparticles. (United States)

    George, Johnsy; Kumar, Ranganathan; Sajeevkumar, Vallayil Appukuttan; Ramana, Karna Venkata; Rajamanickam, Ramalingam; Abhishek, Virat; Nadanasabapathy, Shanmugam; Siddaramaiah


    Hydroxypropyl methyl cellulose (HPMC) based hybrid nanocomposites reinforced with bacterial cellulose nanocrystals (BCNC) and silver nanoparticles (AgNPs) had been prepared and characterised. BCNC was capable of improving the tensile strength and modulus of HPMC, but they made the film more brittle. The addition of AgNPs along with BCNC, helped to regain some of the lost elongation properties without affecting other properties. Moisture sorption analysis proved that the hydrophilicity of the nanocomposite decreased considerably by the addition of these nanomaterials. Several mathematical models were also used to fit the experimental sorption results. A unique combination of two nanomaterials was highly effective in overcoming certain limitations of nanocomposites which uses only one type of nanomaterial. This type of hybrid nanocomposites with superior properties is expected to be useful in eco-friendly food packaging applications.


    Institute of Scientific and Technical Information of China (English)

    ZHANG Lina; LIU Haiqing; ZHENG Lianshuang; ZHANG Jiayao; DU Yumin; LIU Weili


    The biodegradability of Aspergillus niger (A. niger), Mucor (M-305) and Trichoderma (T-311) strains on regenerated cellulose films in media was investigated. The results showed that T-311 strain isolated from soil adhered on the cellulose film fragments has stronger degradation effect on the cellulose film than A. niger strain. The weights, molecular weights and tensile strengths of the cellulose films in both shake culture and solid media decreased with incubation time, accompanied by producing CO2 and saccharides. HPLC, IR and released CO2 analysis indicated that the biodegradation products of the regenerated cellulose films mainly contain oligosaccharides, cellobiose, glucose, arabinose, erythrose, glycerose,glycerol, ethanal, formaldehyde and organic acid, the end products were CO2 and water.After a month, the films were completely decomposed by fungi in the media at 30℃.

  1. Investigating the Mechanical Properties and Degradability of Bioplastics Made from Wheat Straw Cellulose and Date Palm Fiber

    Directory of Open Access Journals (Sweden)

    H Omrani Fard


    Full Text Available During the past two decades, the use of bioplastics as an alternative to regular plastics has received much attention in many different industries. The mechanical and degradable properties of bioplastic are important for their utilization. In this research cellulose of wheat straw and glycerol were mixed by different weight ratios and then reinforced by using date palm fibers. To prepare the bioplastic plates, the materials were poured in molds and pressed by means of a hydraulic press and simultaneously heating of the molds. The experiments were performed based on a 3×3 factorial design with three levels: 50%, 60% and 70% of wheat cellulose and three types of reinforcement methods, namely: no-reinforcement, network reinforcement and parallel string reinforcement. The effect of the two factors on tensile strength, tensile strain, bending strength, modulus of elasticity and modulus of bending were investigated. The results indicated that the two factors and their interactions had significant effects on the mentioned properties of bioplastics (at α=0.05 level . The comparison of the means of the tests showed that the network reinforcement type with 50% cellulose had the highest tensile and bending strengths with 1992.02 and 28.71 MPa, respectively. The maximum modulus of elasticity and modulus bending were 40.4 and 2.3 MPa, respectively for parallel string arrangement and 70% of cellulose. The degradability tests of bioplastic using a fistulated sheep indicated that with increasing the percentage of cellulose, the degradability rate deceased. The maximum degradability rate, after 48 h holding in the sheep rumen, was 74% that belonged to bioplastics with 50% cellulose. The degradability data were well fitted to a mathematical model (R2=0.97.

  2. Increases thermal stability and cellulose-binding capacity of Cryptococcus sp. S-2 lipase by fusion of cellulose binding domain derived from Trichoderma reesei

    Energy Technology Data Exchange (ETDEWEB)

    Thongekkaew, Jantaporn, E-mail: [Department of Biological Science, Faculty of Science, Ubon-Ratchathani University, Warinchumrab, Ubon-Ratchathani 34190 (Thailand); Ikeda, Hiroko; Iefuji, Haruyuki [Application Research Division, National Research Institute of Brewing, 3-7-1 Kagamiyama, Higashi-Hiroshima 739-0046 (Japan)


    Highlights: Black-Right-Pointing-Pointer The CSLP and fusion enzyme were successfully expressed in the Pichia pastoris. Black-Right-Pointing-Pointer The fusion enzyme was stable at 80 Degree-Sign C for 120-min. Black-Right-Pointing-Pointer The fusion enzyme was responsible for cellulose-binding capacity. Black-Right-Pointing-Pointer The fusion enzyme has an attractive applicant for enzyme immobilization. -- Abstract: To improve the thermal stability and cellulose-binding capacity of Cryptococcus sp. S-2 lipase (CSLP), the cellulose-binding domain originates from Trichoderma reesei cellobiohydrolase I was engineered into C-terminal region of the CSLP (CSLP-CBD). The CSLP and CSLP-CBD were successfully expressed in the Pichia pastoris using the strong methanol inducible alcohol oxidase 1 (AOX1) promoter and the secretion signal sequence from Saccharomyces cerevisiae ({alpha} factor). The recombinant CSLP and CSLP-CBD were secreted into culture medium and estimated by SDS-PAGE to be 22 and 27 kDa, respectively. The fusion enzyme was stable at 80 Degree-Sign C and retained more than 80% of its activity after 120-min incubation at this temperature. Our results also found that the fusion of fungal exoglucanase cellulose-binding domain to CSLP is responsible for cellulose-binding capacity. This attribute should make it an attractive applicant for enzyme immobilization.

  3. Dynamic changes of carbon isotope apparent fractionation factor to describe transition to syntrophic acetate oxidation during cellulose and acetate methanization. (United States)

    Vavilin, Vasily A; Rytov, Sergey V


    To identify predominant metabolic pathway for cellulose methanization new equations that take into account dynamics of 13C are added to the basic model of cellulose methanization. The correct stoichiometry of hydrolysis, acidogenesis, acetogenesis and methanogenesis steps including biomass is considered. Using experimental data by Laukenmann et al. [Identification of methanogenic pathway in anaerobic digesters using stable carbon isotopes. Eng. Life Sci. 2010;10:1-6], who reported about the importance of ace`tate oxidation during mesophilic cellulose methanization, the model confirmed that, at high biomass concentration of acetate oxidizers, the carbon isotope fractionation factor amounts to about 1.085. The same model, suggested firstly for cellulose degradation, was used to describe, secondly, changes in, and in methane and carbon dioxide during mesophylic acetate methanization measured by Grossin-Debattista [Fractionnements isotopiques (13C/12C) engendres par la methanogenese: apports pour la comprehension des processus de biodegradation lors de la digestion anaerobie [doctoral thesis]. 2011. Bordeaux: Universite Bordeaux-1;2011. Available from: . French].The model showed that under various ammonium concentrations, at dominating acetoclastic methanogenesis, the value decreases over time to a low level (1.016), while at dominating syntrophic acetate oxidation, coupled with hydrogenotrophic methanogenesis, slightly increases, reaching 1.060 at the end of incubation.

  4. Ultrathin cellulose nanosheet membranes for superfast separation of oil-in-water nanoemulsions (United States)

    Zhou, Ke; Zhang, Qiu Gen; Li, Hong Mei; Guo, Nan Nan; Zhu, Ai Mei; Liu, Qing Lin


    Oily wastewater is generated in diverse industrial processes, and its treatment has become crucial due to increasing environmental concerns. Herein, novel ultrathin nanoporous membranes of cellulose nanosheets have been fabricated for separation of oil-in-water nanoemulsions. The fabrication approach is facile and environmentally friendly, in which cellulose nanosheets are prepared by freeze-extraction of a very dilute cellulose solution. The as-prepared membranes have a cellulose nanosheet layer with a cut-off of 10-12 nm and a controllable thickness of 80-220 nm. They allow ultrafast water permeation and exhibit excellent size-selective separation properties. A 112 nm-thick membrane has a water flux of 1620 l m-2 h-1 bar-1 and a ferritin rejection of 92.5%. These membranes have been applied to remove oil from its aqueous nanoemulsions successfully, and they show an ultrafast and effective separation of oil-in-water nanoemulsions. The newly developed ultrathin cellulose membranes have a wide application in oily wastewater treatment, separation and purification of nanomaterials.Oily wastewater is generated in diverse industrial processes, and its treatment has become crucial due to increasing environmental concerns. Herein, novel ultrathin nanoporous membranes of cellulose nanosheets have been fabricated for separation of oil-in-water nanoemulsions. The fabrication approach is facile and environmentally friendly, in which cellulose nanosheets are prepared by freeze-extraction of a very dilute cellulose solution. The as-prepared membranes have a cellulose nanosheet layer with a cut-off of 10-12 nm and a controllable thickness of 80-220 nm. They allow ultrafast water permeation and exhibit excellent size-selective separation properties. A 112 nm-thick membrane has a water flux of 1620 l m-2 h-1 bar-1 and a ferritin rejection of 92.5%. These membranes have been applied to remove oil from its aqueous nanoemulsions successfully, and they show an ultrafast and effective

  5. Synthesis of hybrid cellulose nanocomposite bonded with dopamine SiO2/TiO2 and its antimicrobial activity (United States)

    Ramesh, Sivalingam; Kim, Gwang-Hoon; Kim, Jaehwan; Kim, Joo-Hyung


    Organic-inorganic hybrid material based cellulose was synthesized by the sol-gel approach. The explosion of activity in this area in the past decade has made tremendous progress in industry or academic both fundamental understanding of sol-gel process and applications of new functionalized hybrid materials. In this present research work, we focused on cellulose-dopamine functionalized SiO2/TiO2 hybrid nanocomposite by sol-gel process. The cellulose-dopamine hybrid nanocomposite was synthesized via γ-aminopropyltriethoxysilane (γ-APTES) coupling agent by in-situ sol-gel process. The chemical structure of cellulose-amine functionalized dopamine bonding to cellulose structure with covalent cross linking hybrids was confirmed by FTIR spectral analysis. The morphological analysis of cellulose-dopamine nanoSiO2/TiO2 hybrid nanocomposite materials was characterized by XRD, SEM and TEM. From this different analysis results indicate that the optical transparency, thermal stability, control morphology of cellulose-dopamine-SiO2/TiO2 hybrid nanocomposite. Furthermore cellulose-dopamine-SiO2/TiO2 hybrid nanocomposite was tested against pathogenic bacteria for antimicrobial activity.

  6. Prisonniers de Guerre aux Mains de Leur Puissance D’origine : Pour Une Application des Conventions de Genève Jusqu’à Leur « Libération et Rapatriement Définitifs »

    Directory of Open Access Journals (Sweden)

    Frédéric Gouin


    transfert (ex. l’Afghanistan, l’Irak soit parce qu’ils ont toujours fait partie de l’opposition à leurs autorités. Le transfert à un pays qui aurait dû leur offrir au moins la protection consulaire, et ne l’a pas fait, signifie qu’ils sont encore une fois mis en prison, abusés, torturés, menacés, privés de contact avec leur famille, etc. Dans cet article, on soutient que les prisonniers de guerre devraient continuer à bénéficier de ce statut si ils sont transférés à un pays qui va continuer à les détenir essentiellement à cause de leur participation à un conflit armé, même si le pays qui les reçoit est le pays d’origine du prisonnier de guerre. Cette position repose sur trois arguments : (1 la Convention de Genève sur les prisonniers de guerre précise qu’elle continue à s’appliquer jusqu’à «la libération et le rapatriement définitifs»; (2 les obligations internationales interdisent de transférer quelqu’un à un pays où il ou elle craint être persécuté; (3 la loyauté plutôt que la nationalité devrait être la base pour déterminer si un individu a droit à la protection de la Convention de Genève sur les prisonniers de guerre.

  7. Nouvelle stratégie pour l'amélioration de la brillance d'une source VUV nanoseconde (United States)

    Chénais, S.; Castex, M.-C.


    Nous présentons une technique simple pour améliorer d'un à deux ordres de grandeur l'énergie d'un rayonnement cohérent à 125 nm, obtenu par somme de fréquence résonante dans une vapeur de mercure à température ambiante. En focalisant sur la surface de mercure un laser ArF à 193 nm, le signal VUV est multiplié par 6, facteur qui peut s'élever jusqu'à ˜ 60 lorsque l'intensité des faisceaux fondamentaux est réduite. Cette expérience de validation ouvre de nombreuses opportunités d'amélioration pour une source VUV de forte brillance, applicable à la nanostructuration de matériaux pour l'optique.

  8. Antibacterial paperboard packaging using microfibrillated cellulose. (United States)

    Lavoine, Nathalie; Desloges, Isabelle; Manship, Brigitte; Bras, Julien


    The industry and consumers are focusing more and more on the development of biodegradable and lightweight food-packaging materials, which could better preserve the quality of the food and improve its shelf-life. In an attempt to meet these requirements, this study presents a novel bio-substrate able to contain active bio-molecules for future food-packaging applications. Based on a paperboard substrate, the development of an antibacterial bio-packaging material is, therein, achieved using a chlorhexidine digluconate (CHX) solution as a model of an antibacterial molecule, mixed with microfibrillated cellulose (MFC) and used as coating onto paperboard samples. AFM and FE-SEM analyses were performed to underline the nanoporous MFC network able to trap and to progressively release the CHX molecules. The release study of CHX was conducted in an aqueous medium and showed a lower proportion (20 %) of CHX released when using MFC. This led to the constant release of low amounts of CHX over 40 h. Antibacterial tests were carried out to assess the preservation of the antibacterial activity of the samples after the release studies. Samples remained active against Bacillus subtilis, with better results being obtained when MFC was used. The preservation of the quality of a model food was finally evaluated paving the way for future promising applications in the food packaging industry.

  9. Les polymères issus du végétal : matériaux à propriétés spécifiques pour des applications ciblées en industrie plastique

    Directory of Open Access Journals (Sweden)

    Dubois P.


    Full Text Available Features of plant-based polymers with special applications in plastic fi eld. The new interest of plastic fi eld with renewable resources results from a global environmental respect awareness and the fossil depletion problem. In these perspectives, vegetable raw materials mainly polymers show attractive properties with great interests in plastic industry such as biodegradability, biocompatibility, selective permeability or variability in physico-mechanical properties. These properties have targeted applications in various fi elds specifi cally packaging, agricultural, textile, pharmaceutical, electronic or medical domains. This paper describes the different raw materials from plants and their valuable properties in relation with potential applications

  10. Pour une Écologie des Somatiques?

    Directory of Open Access Journals (Sweden)



    Full Text Available Ce texte traite de la parenté conceptuelle et théorique entre Somatiques et Écologie scientifique. Après une définition de la notion scientifique d’écologie, il s’attache à définir trois notions clés de l’écologie: celle de potentiel, qui permet de décrire de façon innovante le modèle de relation entre sujet et environnement au sein des Somatiques, et celles de diversité et de réciprocité, à partir desquelles l’article se veut une invitation et un programme à penser l’intégration des Somatiques au paradigme écologique scientifique, et en appelle aux acteurs somatiques pour transformer leurs pratiques selon une éthique environnementale.

  11. A lunguistica pour ses quarante ans

    Directory of Open Access Journals (Sweden)

    Ludvik Horvat Le Doyen


    Full Text Available En tant que doyen de la Faculté des Lettres de l'Universite de Ljubljana, j'ai l'honneur d'introduire le volume qui celebre les quarante ans de publication de cette revue linguistique. La parution de la revue conçua à l' origine comme supplàment pour la linguistique non slave de la revue Slavistična revija (dont la renommée était déjà affirmée, eut lieu en 1958. Ses inspirateurs, ses fondateurs et ses premiers directeurs, auxquels nous gardons une profonde reconnaissance, furent l'italianiste Stanko Škerlj et le latiniste Milan Grošelj, professeurs de notre Faculté. Des sa quatrieme année ce modeste supplement devint revue autonome, telle que nous la connaissons aujourd'hui.

  12. Fabrication and Characterization of Regenerated Cellulose Films Using Different Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Jin-Hui Pang


    Full Text Available The demand for substitution of fossil-based materials by renewable bio-based materials is increasing with the fossil resources reduction and its negative impacts on the environment. In this study, environmentally friendly regenerated cellulose films were successfully prepared using 1-allyl-3-methylimidazolium chloride (AmimCl, 1-butyl-3-methylimidazolium chloride (BmimCl, 1-ethyl-3-methylimidazolium chloride (EmimCl, and 1-ethyl-3-methylimidazolium acetate (EmimAc as solvents, respectively. The results of morphology from scanning electron microscopy (SEM and atomic force microscopy (AFM showed that all the cellulose films possessed smooth, highly uniform, and dense surface. The solid-state cross-polarization/magic angle spinning (CP/MAS 13C NMR spectra and X-ray diffraction (XRD corroborated that the transition from cellulose I to II had occurred after preparation. Moreover, it was shown that the ionic liquid EmimAc possessed much stronger dissolubility for cellulose as compared with other ionic liquids and the cellulose film regenerated from EmimCl exhibited the most excellent tensile strength (119 Mpa. The notable properties of regenerated cellulose films are promising for applications in transparent biodegradable packaging and agricultural purpose as a substitute for PP and PE.

  13. Preparation and characterization of regenerated cellulose membranes from natural cotton fiber

    Directory of Open Access Journals (Sweden)

    Yanjuan CAO


    Full Text Available A series of organic solutions with different cellulose concentrations are prepared by dissolving natural cotton fibers in lithium chloride/dimethyl acetamide (LiCl/DMAC solvent system after the activation of cotton fibers. Under different coagulating bath, the regenerated cellulose membranes are formed in two kinds of coagulation baths, and two coating methods including high-speed spin technique (KW-4A spin coating machine and low-speed scraping (AFA-Ⅱ Film Applicator are selected in this paper. The macromolecular structure, mechanical properties, crystallinity, thermal stability and wetting property of the regenerated cellulose membrane are characterized by Scanning Electron Microscope(SEM, Fourier Transform Infrared Spectroscopy (FT-IR,X-ray diffraction (XRD, Thermogravimetric analysis (TG and contacting angle tester. The effects of mass fraction, coagulation bath type, membrane forming process on the regenerated membrane properties are investigated. Experimental results show that the performance of regenerated cellulose membrane is relatively excellent under the condition of using the KW-4A high-speed spin method, water coagulation bath, and when mass fraction of cellulose is 3.5%. The crystallinity of the regenerated cellulose membrane changes a lot compared with natural cotton fibers. The variation trend of thermal stability is similar with that of cotton fiber. But thermal stability is reduced to some degree, while the wetting ability is improved obviously.

  14. From Cellulosic Based Liquid Crystalline Sheared Solutions to 1D and 2D Soft Materials

    Directory of Open Access Journals (Sweden)

    Maria Helena Godinho


    Full Text Available Liquid crystalline cellulosic-based solutions described by distinctive properties are at the origin of different kinds of multifunctional materials with unique characteristics. These solutions can form chiral nematic phases at rest, with tuneable photonic behavior, and exhibit a complex behavior associated with the onset of a network of director field defects under shear. Techniques, such as Nuclear Magnetic Resonance (NMR, Rheology coupled with NMR (Rheo-NMR, rheology, optical methods, Magnetic Resonance Imaging (MRI, Wide Angle X-rays Scattering (WAXS, were extensively used to enlighten the liquid crystalline characteristics of these cellulosic solutions. Cellulosic films produced by shear casting and fibers by electrospinning, from these liquid crystalline solutions, have regained wider attention due to recognition of their innovative properties associated to their biocompatibility. Electrospun membranes composed by helical and spiral shape fibers allow the achievement of large surface areas, leading to the improvement of the performance of this kind of systems. The moisture response, light modulated, wettability and the capability of orienting protein and cellulose crystals, opened a wide range of new applications to the shear casted films. Characterization by NMR, X-rays, tensile tests, AFM, and optical methods allowed detailed characterization of those soft cellulosic materials. In this work, special attention will be given to recent developments, including, among others, a moisture driven cellulosic motor and electro-optical devices.

  15. Preparation of cellulose based microspheres by combining spray coagulating with spray drying. (United States)

    Wang, Qiao; Fu, Aiping; Li, Hongliang; Liu, Jingquan; Guo, Peizhi; Zhao, Xiu Song; Xia, Lin Hua


    Porous microspheres of regenerated cellulose with size in range of 1-2 μm and composite microspheres of chitosan coated cellulose with size of 1-3 μm were obtained through a two-step spray-assisted approach. The spray coagulating process must combine with a spray drying step to guarantee the formation of stable microspheres of cellulose. This approach exhibits the following two main virtues. First, the preparation was performed using aqueous solution of cellulose as precursor in the absence of organic solvent and surfactant; Second, neither crosslinking agent nor separated crosslinking process was required for formation of stable microspheres. Moreover, the spray drying step also provided us with the chance to encapsulate guests into the resultant cellulose microspheres. The potential application of the cellulose microspheres acting as drug delivery vector has been studied in two PBS (phosphate-buffered saline) solution with pH values at 4.0 and 7.4 to mimic the environments of stomach and intestine, respectively.

  16. Study of nano-fiber cellulose production by Glucanacetobacter xylinum ATCC 10245. (United States)

    Norouzian, D; Farhangi, A; Tolooei, S; Saffari, Z; Mehrabi, M R; Chiani, M; Ghassemi, S; Farahnak, M; Akbarzadeh, A


    Bacterial Celluloses (BC) are gaining importance in research and commerce due to numerous factors affecting the bacterial cellulose characteristics and application in different industries. The aim of the present study was to produce bacterial cellulose in different media using different cultivation vessels. Bacterial cellulose was produced by static cultivation of Glucanacetobacter xylinum ATCC 10245 in different culture media such as Brain Heart Agar, Luria Bertani Agar /Broth, Brain Heart Infusion, Hestrin-Schramm and medium no. 125. Cultivation of bacterium was conducted in various culture vessels with different surface area. The cellulose membrane was treated and purified with a 0.1 M NaOH solution at 90 degreesC for 30 min and dried by a freeze- drier at -40 degreesC to obtain BC. The prepared bacterial cellulose was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD). The amount of produced BC was related directly to the surface area of culture vessels.

  17. Improvement production of bacterial cellulose by semi-continuous process in molasses medium. (United States)

    Cakar, Fatih; Ozer, Işılay; Aytekin, A Özhan; Sahin, Fikrettin


    Bacterial cellulose (BC) has unique properties such as structural, functional, physical and chemical. The mass production of BC for industrial application has recently become attractive to produce more economical and high productive cellulose. In this study, to improve the productivity of bacterial cellulose (BC), BC production by Gluconacetobacter xylinus FC01 was investigated in molasses medium with static semi-continuous operation mode. Cell dry weight, polysaccharide, sugar and cellulose concentrations were monitored and cellulose was characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The highest cellulose yield (1.637 g/L) was obtained in SCP50-7d, which molasses of 1/2 ratio for 7 days by static semi-continuous operation mode. The results show that BC can be highly produced by G. xylinus in molasses with static semi-continuous process than batch process. We claimed that low-cost medium with semi-continuous operation mode in static culture is a good candidate for industrial scale BC productions.

  18. Green route to modification of wood waste, cellulose and hemicellulose using reactive extrusion. (United States)

    Vaidya, Alankar A; Gaugler, Marc; Smith, Dawn A


    A large volume of wood waste is produced in timber processing industry which traditionally used in low value applications. Here, value addition to the wood waste (Sander dust) and cellulose, hemicellulose isolated thereof by functionalisation using cyclic anhydrides in a solvent-free and green reactive extrusion process is reported. The effect of extrusion temperature, catalyst and different weight ratios of Sander dust (SD):succinic anhydride (SA) on the esterification reaction is evaluated. The esterified products were characterised by the acid value, degree of substitution (DS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), solid state (13)C NMR and thermo-gravimetric analysis (TGA). Under optimum extrusion conditions, mixed esters are formed, with highest acid value obtained for succinylation of cellulose (0.122 g/g at DS of 0.350) which is two times higher compared to succinylated SD (0.059 g/g at a weight gain of 0.452) and hemicellulose (0.043 g/g at DS of 0.290). The reactivity trend for individual anhydride was: (1) SA-Cellulose>SD>hemicellulose; (2) maleic anhydride (MA)-SD>hemicellulose>cellulose and (3) dodecenyl succinic anhydride (DDSA)-SD ≈ cellulose ≫ hemicellulose. The pendant free carboxyl groups generated through functionalisation of wood waste, cellulose and hemicellulose without the presence of polymeric carriers will allow more tailored or targeted modification of wood-plastic composites.

  19. La conception à l’ère de l’Internet des Objets : modèles et principes pour le design de produits aux fonctions augmentées par des applications.


    Thebault, Pierrick


    The Internet of Things, whose underlying vision and technologies aim at bridging the physical and digital worlds together, lead to the creation of new types of applications coupling Web services with everyday products. Such product-oriented applications, which enable the functional exposition, control or enhancement of artifacts that embed information processing capabilities, question the established design principles and conventions. They open up the possibility for Internet-enabled products...

  20. 离子液体1-乙基-3-甲基咪唑醋酸盐的制备及用于纤维素溶解纺丝的研究进展%Progress in Preparation of Ionic Liquid 1-Ethyl-3-Methylimidazolium Acetate and Application in Dissolution and Spinning of Cellulose

    Institute of Scientific and Technical Information of China (English)

    程春祖; 朱庆松; 孙玉山; 李晓俊; 徐纪刚


    离子液体1-乙基-3-甲基咪唑醋酸盐([EMIM3Ac)可以溶解天然高分子等许多聚合物,尤其对于纤维素具有较强的溶解能力,且溶解过程基本不造成纤维素降解,故可以作为纤维素的有效溶剂,用于纤维素的溶解加工。与其它溶剂相比,[EMIM]Ac具有使用安全、不污染环境、易回收循环利用等优势,故在纤维素溶解、纺丝方面具有广阔的应用前景。本文主要介绍了[EMIM]Ac的多种制备方法及其优缺点,这对其它醋酸盐类离子液体的制备也具有指导意义;并概述了[EMIM]Ac在纤维素溶解、纺丝等方面的应用研究。%Ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]Ae), which has stronger ability to dissolve cellulose especially, can be used to dissolve natural polymer and many other polymers. As the dissolving process of cellulose causes no degradation, [EMIM]Ac can be used as an effective solution in dissolving and proeessing of eellulose. Compared with other solutions, [EMIM]Ae has many advantages of use safety, no pollution to environment and easy recovery recycling, and has wide application prospect in the dissolving and spinning of cellulose. Various preparation methods of [EMIM]Ac and their advantages or disadvantages are introduced in this paper, which have a guiding significance to the preparations of other acetic acid salts ionic liquid. And the application research of [EMIM]Ac in cellulose dissolving and spinning is summarized.

  1. Amphiphilic Cellulose Ethers Designed for Amorphous Solid Dispersion via Olefin Cross-Metathesis. (United States)

    Dong, Yifan; Mosquera-Giraldo, Laura I; Taylor, Lynne S; Edgar, Kevin J


    The design of cellulose ether-based amphiphiles has been difficult and limited because of the harsh conditions typically required for appending ether moieties to cellulose. Olefin cross-metathesis recently has been shown to be a valuable approach for appending a variety of functional groups to cellulose ethers and esters, provided that an olefin handle for metathesis can be attached. This synthetic pathway gives access to these functional derivatives under very mild conditions and at high efficiency. Modification of ethyl cellulose by metathesis to prepare useful derivatives, for example, for solubility and bioavailability enhancement of drugs by amorphous solid dispersion (ASD), has been limited by the low DS(OH) of commercial ethyl cellulose derivatives. This is problematic because ethyl cellulose is otherwise a very attractive substrate for synthesis of amphiphilic derivatives by olefin metathesis. Herein we explore two methods for opening up this design space for ether-based amphiphiles, for example, permitting synthesis of more hydrophilic derivatives. One approach is to start with the more hydrophilic commercial methyl cellulose, which contains much higher DS(OH) and therefore is better suited for introduction of high DS of olefin metathesis "handles". In another approach, we explored a homogeneous one-pot synthesis methodology from cellulose, where controlled DS of ethyl groups was introduced at the same time as the ω-unsaturated alkyl groups, thereby permitting complete control of DS(OH), DS(Et), and ultimately DS of the functional group added by metathesis. We describe the functionalized derivatives available by these successful approaches. In addition, we explore new methods for reduction of the unsaturation in initial metathesis products to provide robust methods for enhancing product stability against further radical-catalyzed reactions. We demonstrate initial evidence that the products show strong promise as amphiphilic matrix polymers for amorphous

  2. Rheology and thermal degradation of isocyanate-functionalized methyl cellulose-based oleogels. (United States)

    Gallego, R; Arteaga, J F; Valencia, C; Franco, J M


    The -NCO-functionalization of methyl cellulose with HMDI and its application to chemically gel the castor oil is explored in this work by analyzing the influence of functionalization degree on the rheological and thermogravimetric behavior of resulting chemical oleogels. With this aim, different methyl cellulose chemical modifications were achieved by limiting the proportion of HMDI and, subsequently, oleogels were obtained by dispersing these polymers in castor oil and promoting the reaction between those biopolymers and the hydroxyl groups located in the ricinoleic fatty acid chain. -NCO-functionalized methyl cellulose-based oleogels were characterized from themogravimetric and rheological points of view. Suitable thermal resistance and rheological characteristics were found in order to propose these oleogels as promising bio-based alternatives to traditional lubricating greases based on non-renewable resources. In general, -NCO-functionalized methyl cellulose thermally decomposed in three main steps whereas resulting oleogels thermal decomposition takes place in one main single stage which comprises the thermal degradation of both the polymer and the castor oil. Temperature range for thermal degradation is broadened when using highly -NCO-functionalized methyl cellulose. A cross-linked viscoelastic gel was obtained with methyl cellulose functionalized in a relatively low degree (around 6% -NCO molar content). The rheological properties of highly functionalized methyl cellulose-based oleogels evolve during several months of aging, but mainly during the first week, due to the progress of the reaction between -NCO functional groups and castor oil -OH groups. SAOS functions analyzed and oleogel relative elasticity increase with the functionalization degree. Oleogel linear viscoelastic response is also extremely dependent on NCO-functionalized methyl cellulose concentration.

  3. Utilization of purified cellulose in fiber studies. (United States)

    Penner, M H; Liaw, E T


    Purified cellulose-type fiber products are widely used in experimental nutrition. Their use in a broad spectrum of studies may potentially lead to the acceptance of the misconception that the various commercially available cellulose products are equivalent. In this paper we have attempted to show that this is not the case. The comparative structural data of Table 2 and the compositional data of Olsen et al provide examples which indicate that purified cellulose preparations should not necessarily be considered equivalent. Unfortunately, our current lack of understanding of how fibers are metabolized and how they may affect specific physiological parameters makes it difficult to determine which, if any, of the measurable structural and chemical properties will be of relevance for a given in vivo study. At present, it appears that researchers utilizing/evaluating the consequences of consuming a purified cellulose-type fiber would be prudent to provide at least a limited amount of data on the properties of the cellulose preparation used in their studies. The characterization of the cellulose product may be done by a variety of methods depending on the expertise of the laboratory. The methods and results discussed in this paper provide an example of the type of information which may be obtained from an in vitro characterization of cellulose products.

  4. A novel cellulose hydrogel prepared from its ionic liquid solution

    Institute of Scientific and Technical Information of China (English)

    LI Lu; LIN ZhangBi; YANG Xiao; WAN ZhenZhen; CUI ShuXun


    A novel cellulose hydrogel is prepared by regenerating cellulose from its ionic liquid solution. The transparency cellulose hydrogel presents a good chemical stability and an acceptable mechanical property. This non-toxic cellulose hydrogel should be biocompatibie and may be useful in the future as a biomaterial.

  5. Model films of cellulose. I. Method development and initial results

    NARCIS (Netherlands)

    Gunnars, S.; Wågberg, L.; Cohen Stuart, M.A.


    This report presents a new method for the preparation of thin cellulose films. NMMO (N- methylmorpholine- N-oxide) was used to dissolve cellulose and addition of DMSO (dimethyl sulfoxide) was used to control viscosity of the cellulose solution. A thin layer of the cellulose solution is spin- coated

  6. Surface modification of cellulose nanocrystals

    Institute of Scientific and Technical Information of China (English)

    WANG Neng; DING Enyong; CHENG Rongshi


    In order to improve the dispersibility of cellulose nanocrystal(CNC) particles,three difierent grafted reactions of acetylation,hydroxyethylation and hydroxypropylation were introduced to modify the CNC surface.The main advantages of these methods were the simple and easily controlled reaction conditions,and the dispersibility of the resulting products was distinctly improved.The properties of the modified CNC were characterized by means of Fourier transform infrared spectroscopy(FT-IR),13 C nuclear magnetic resonance(NMR),transmission electron microscopy(TEM)and thermogravimetric analyses(TGA).The results indicated mat after desiccation,the modification products could be dispersed again in the proper solvents by ultrasonic treatments,and the diameter of their particles had no obvious changes.However,their thermal degradation behaviors were quite different.The initial decomposition temperature of the modified products via hydroxyethylation or hydroxypropylation was lower than that of modified products via acetylation.

  7. Chemical structure analysis of starch and cellulose derivatives. (United States)

    Mischnick, Petra; Momcilovic, Dane


    Starch and cellulose are the most abundant and important representatives of renewable biomass. Since the mid-19th century their properties have been changed by chemical modification for commercial and scientific purposes, and there substituted polymers have found a wide range of applications. However, the inherent polydispersity and supramolecular organization of starch and cellulose cause the products resulting from their modification to display high complexity. Chemical composition analysis of these mixtures is therefore a challenging task. Detailed knowledge on substitution patterns is fundamental for understanding structure-property relationships in modified cellulose and starch, and thus also for the improvement of reproducibility and rational design of properties. Substitution patterns resulting from kinetically or thermodynamically controlled reactions show certain preferences for the three available hydroxyl functions in (1→4)-linked glucans. Spurlin, seventy years ago, was the first to describe this in an idealized model, and nowadays this model has been extended and related to the next hierarchical levels, namely, the substituent distribution in and over the polymer chains. This structural complexity, with its implications for data interpretation, and the analytical approaches developed for its investigation are outlined in this article. Strategies and methods for the determination of the average degree of substitution (DS), monomer composition, and substitution patterns at the polymer level are presented and discussed with respect to their limitations and interpretability. Nuclear magnetic resonance spectroscopy, chromatography, capillary electrophoresis, and modern mass spectrometry (MS), including tandem MS, are the main instrumental techniques employed, in combination with appropriate sample preparation by chemical and enzymatic methods.

  8. Biocompatible cellulose-based superabsorbent hydrogels with antimicrobial activity. (United States)

    Peng, Na; Wang, Yanfeng; Ye, Qifa; Liang, Lei; An, Yuxing; Li, Qiwei; Chang, Chunyu


    Current superabsorbent hydrogels commercially applied in the disposable diapers have disadvantages such as weak mechanical strength, poor biocompatibility, and lack of antimicrobial activity, which may induce skin allergy of body. To overcome these hassles, we have developed novel cellulose based hydrogels via simple chemical cross-linking of quaternized cellulose (QC) and native cellulose in NaOH/urea aqueous solution. The prepared hydrogel showed superabsorbent property, high mechanical strength, good biocompatibility, and excellent antimicrobial efficacy against Saccharomyces cerevisiae. The presence of QC in the hydrogel networks not only improved their swelling ratio via electrostatic repulsion of quaternary ammonium groups, but also endowed their antimicrobial activity by attraction of sections of anionic microbial membrane into internal pores of poly cationic hydrogel leading to the disruption of microbial membrane. Moreover, the swelling properties, mechanical strength, and antibacterial activity of hydrogels strongly depended on the contents of quaternary ammonium groups in hydrogel networks. The obtained data encouraged the use of these hydrogels for hygienic application such as disposable diapers.

  9. Cellulose nanofiber extraction from grass by a modified kitchen blender (United States)

    Nakagaito, Antonio Norio; Ikenaga, Koh; Takagi, Hitoshi


    Cellulose nanofibers have been used to reinforce polymers, delivering composites with strength that in some cases can be superior to that of engineering plastics. The extraction of nanofibers from plant fibers can be achieved through specialized equipment that demands high energy input, despite delivering extremely low yields. The high extraction cost confines the use of cellulose nanofibers to the laboratory and not for industrial applications. This study aims to extract nanofibers from grass by using a kitchen blender. Earlier studies have demonstrated that paper sheets made of blender-extracted nanofibers (after 5 min to 10 min of blending) have strengths on par with paper sheets made from commercially available cellulose nanofibers. By optimizing the design of the blender bottle, nanofibrillation can be achieved in shorter treatment times, reducing the energy consumption (in the present case, to half) and the overall extraction cost. The raw materials used can be extended to the residue straw of agricultural crops, as an alternative to the usual pulp fibers obtained from wood.

  10. Physical and mechanical properties of modified bacterial cellulose composite films (United States)

    Indrarti, Lucia; Indriyati, Syampurwadi, Anung; Pujiastuti, Sri


    To open wide range application opportunities of Bacterial Cellulose (BC) such as for agricultural purposes and edible film, BC slurries were blended with Glycerol (Gly), Sorbitol (Sor) and Carboxymethyl Cellulose (CMC). The physical and mechanical properties of BC composites were investigated to gain a better understanding of the relationship between BC and the additive types. Addition of glycerol, sorbitol and CMC influenced the water solubility of BC composite films. FTIR analysis showed the characteristic bands of cellulose. Addition of CMC, glycerol, and sorbitol slightly changed the FTIR spectrum of the composites. Tensile test showed that CMC not only acted as cross-linking agent where the tensile strength doubled up to 180 MPa, but also acted as plasticizer with the elongation at break increased more than 100% compared to that of BC film. On the other hand, glycerol and sorbitol acted as plasticizers that decreased the tensile strength and increased the elongation. Addition of CMC can improve film transparency, which is quite important in consumer acceptance of edible films in food industry.

  11. Lyocell, The New Generation of Regenerated Cellulose

    Directory of Open Access Journals (Sweden)

    Éva Borbély


    Full Text Available For the majority of the last century, commercial routes to regenerated cellulosefibres have coped with the difficulties of making a good cellulose solution by using an easyto dissolve derivative (e.g. xanthane in the case of viscose rayon or complex (e.g.cuprammonium rayon. For the purposes of this paper, advanced cellulosic fibres aredefined as those made from a process involving direct dissolution of cellulose. The firstexamples of such fibres have now been generically designaed as lyocell fibres todistinguish them from rayons, and the first commercial lyocell fibre is Courtaulds’ Tencel.

  12. Oxidizing Cellulose to 2,3-Dialdehyde Cellulose by Sodium Periodate

    Institute of Scientific and Technical Information of China (English)

    MENG Shuxian; FENG Yaqing; LIANG Zupei; FU Qiang; ZHANG Enzhong


    Study on oxidizing cellulose to 2,3-dialdehyde cellulose by sodium periodate (NaIO4) was carried out. The effects of reaction conditions such as pH of solution, temperature, oxidant concentration, oxidation time, the particle size of 2,3-dialdehyde cellulose and alkali treatment temperature on the dialdehyde concentration of cellulose were investigated in detail. The results show that the aldehyde group content was created while reaction temperature and alkali treatment temperature increased.The most principal factors affecting the aldehyde group content of 2,3-dialdehyde cellulose were found out and the best oxidation conditions were as follows: the pH was 2, the reaction temperature was 45 ℃, the mass ratio of cellulose to NaIO4 was 1/2, the reaction time was 4 h, the alkali treatment temperature was 70 ℃ and smaller particle size was 0.80 mm.

  13. Cellulose-builder: a toolkit for building crystalline structures of cellulose. (United States)

    Gomes, Thiago C F; Skaf, Munir S


    Cellulose-builder is a user-friendly program that builds crystalline structures of cellulose of different sizes and geometries. The program generates Cartesian coordinates for all atoms of the specified structure in the Protein Data Bank format, suitable for using as starting configurations in molecular dynamics simulations and other calculations. Crystalline structures of cellulose polymorphs Iα, Iβ, II, and III(I) of practically any size are readily constructed which includes parallelepipeds, plant cell wall cellulose elementary fibrils of any length, and monolayers. Periodic boundary conditions along the crystallographic directions are easily imposed. The program also generates atom connectivity file in PSF format, required by well-known simulation packages such as NAMD, CHARMM, and others. Cellulose-builder is based on the Bash programming language and should run on practically any Unix-like platform, demands very modest hardware, and is freely available for download from

  14. Preparation and properties of self-reinforced cellulose composite films from Agave microfibrils using an ionic liquid. (United States)

    Reddy, K Obi; Zhang, Jinming; Zhang, Jun; Rajulu, A Varada


    The applications of natural fibers and their microfibrils are increasing rapidly due to their environment benefits, specific strength properties and renewability. In the present work, we successfully extracted cellulose microfibrils from Agave natural fibers by chemical method. The extracted microfibrils were characterized by chemical analysis. The cellulose microfibrils were found to dissolve in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) to larger extent along with little quantity of undissolved microfibrils. Using this solution, the self-reinforced regenerated cellulose composite films were prepared. The raw fiber, extracted cellulose microfibrils and regenerated cellulose composite films were characterized by FTIR, (13)C CP-MAS NMR, XRD, TGA and SEM techniques. The average tensile strength, modulus and elongation at break of the self-reinforced cellulose composite films were found to be 135 MPa, 8150 MPa and 3.2%, respectively. The high values of tensile strength and modulus were attributed to the self-reinforcement of Agave fibers in their generated matrix. These self-reinforced cellulose biodegradable composite films prepared from renewable source can find applications in packaging field.

  15. Fabrication of electric papers of graphene nanosheet shelled cellulose fibres by dispersion and infiltration as flexible electrodes for energy storage. (United States)

    Kang, Yan-Ru; Li, Ya-Li; Hou, Feng; Wen, Yang-Yang; Su, Dong


    An electrically conductive and electrochemically active composite paper of graphene nanosheet (GNS) coated cellulose fibres was fabricated via a simple paper-making process of dispersing chemically synthesized GNS into a cellulose pulp, followed by infiltration. The GNS nanosheet was deposited onto the cellulose fibers, forming a coating, during infiltration. It forms a continuous network through a bridge of interconnected cellulose fibres at small GNS loadings (3.2 wt%). The GNS/cellulose paper is as flexible and mechanically tough as the pure cellulose paper. The electrical measurements show the composite paper has a sheet resistance of 1063 Ω□(-1) and a conductivity of 11.6 S m(-1). The application of the composite paper as a flexible double layer supercapacitor in an organic electrolyte (LiPF(6)) displays a high capacity of 252 F g(-1) at a current density of 1 A g(-1) with respect to GNS. Moreover, the paper can be used as the anode in a lithium battery, showing distinct charge and discharge performances. The simple process for synthesising the GNS functionalized cellulose papers is attractive for the development of high performance papers for electrical, electrochemical and multifunctional applications.

  16. Optical and mechanical properties of nanofibrillated cellulose: Toward a robust platform for next-generation green technologies. (United States)

    Simão, Claudia D; Reparaz, Juan S; Wagner, Markus R; Graczykowski, Bartlomiej; Kreuzer, Martin; Ruiz-Blanco, Yasser B; García, Yamila; Malho, Jani-Markus; Goñi, Alejandro R; Ahopelto, Jouni; Sotomayor Torres, Clivia M


    Nanofibrillated cellulose, a polymer that can be obtained from one of the most abundant biopolymers in nature, is being increasingly explored due to its outstanding properties for packaging and device applications. Still, open challenges in engineering its intrinsic properties remain to address. To elucidate the optical and mechanical stability of nanofibrillated cellulose as a standalone platform, herein we report on three main findings: (i) for the first time an experimental determination of the optical bandgap of nanofibrillated cellulose, important for future modeling purposes, based on the onset of the optical bandgap of the nanofibrillated cellulose film at Eg≈275 nm (4.5 eV), obtained using absorption and cathodoluminescence measurements. In addition, comparing this result with ab-initio calculations of the electronic structure the exciton binding energy is estimated to be Eex≈800 meV; (ii) hydrostatic pressure experiments revealed that nanofibrillated cellulose is structurally stable at least up to 1.2 GPa; and (iii) surface elastic properties with repeatability better than 5% were observed under moisture cycles with changes of the Young modulus as large as 65%. The results obtained show the precise determination of significant properties as elastic properties and interactions that are compared with similar works and, moreover, demonstrate that nanofibrillated cellulose properties can be reversibly controlled, supporting the extended potential of nanofibrillated cellulose as a robust platform for green-technology applications.

  17. Brittle Culm1, a COBRA-like protein, functions in cellulose assembly through binding cellulose microfibrils. (United States)

    Liu, Lifeng; Shang-Guan, Keke; Zhang, Baocai; Liu, Xiangling; Yan, Meixian; Zhang, Lanjun; Shi, Yanyun; Zhang, Mu; Qian, Qian; Li, Jiayang; Zhou, Yihua


    Cellulose represents the most abundant biopolymer in nature and has great economic importance. Cellulose chains pack laterally into crystalline forms, stacking into a complicated crystallographic structure. However, the mechanism of cellulose crystallization is poorly understood. Here, via functional characterization, we report that Brittle Culm1 (BC1), a COBRA-like protein in rice, modifies cellulose crystallinity. BC1 was demonstrated to be a glycosylphosphatidylinositol (GPI) anchored protein and can be released into cell walls by removal of the GPI anchor. BC1 possesses a carbohydrate-binding module (CBM) at its N-terminus. In vitro binding assays showed that this CBM interacts specifically with crystalline cellulose, and several aromatic residues in this domain are essential for binding. It was further demonstrated that cell wall-localized BC1 via the CBM and GPI anchor is one functional form of BC1. X-ray diffraction (XRD) assays revealed that mutations in BC1 and knockdown of BC1 expression decrease the crystallite width of cellulose; overexpression of BC1 and the CBM-mutated BC1s caused varied crystallinity with results that were consistent with the in vitro binding assay. Moreover, interaction between the CBM and cellulose microfibrils was largely repressed when the cell wall residues were pre-stained with two cellulose dyes. Treating wild-type and bc1 seedlings with the dyes resulted in insensitive root growth responses in bc1 plants. Combined with the evidence that BC1 and three secondary wall cellulose synthases (CESAs) function in different steps of cellulose production as revealed by genetic analysis, we conclude that BC1 modulates cellulose assembly by interacting with cellulose and affecting microfibril crystallinity.

  18. Brittle Culm1, a COBRA-like protein, functions in cellulose assembly through binding cellulose microfibrils.

    Directory of Open Access Journals (Sweden)

    Lifeng Liu

    Full Text Available Cellulose represents the most abundant biopolymer in nature and has great economic importance. Cellulose chains pack laterally into crystalline forms, stacking into a complicated crystallographic structure. However, the mechanism of cellulose crystallization is poorly understood. Here, via functional characterization, we report that Brittle Culm1 (BC1, a COBRA-like protein in rice, modifies cellulose crystallinity. BC1 was demonstrated to be a glycosylphosphatidylinositol (GPI anchored protein and can be released into cell walls by removal of the GPI anchor. BC1 possesses a carbohydrate-binding module (CBM at its N-terminus. In vitro binding assays showed that this CBM interacts specifically with crystalline cellulose, and several aromatic residues in this domain are essential for binding. It was further demonstrated that cell wall-localized BC1 via the CBM and GPI anchor is one functional form of BC1. X-ray diffraction (XRD assays revealed that mutations in BC1 and knockdown of BC1 expression decrease the crystallite width of cellulose; overexpression of BC1 and the CBM-mutated BC1s caused varied crystallinity with results that were consistent with the in vitro binding assay. Moreover, interaction between the CBM and cellulose microfibrils was largely repressed when the cell wall residues were pre-stained with two cellulose dyes. Treating wild-type and bc1 seedlings with the dyes resulted in insensitive root growth responses in bc1 plants. Combined with the evidence that BC1 and three secondary wall cellulose synthases (CESAs function in different steps of cellulose production as revealed by genetic analysis, we conclude that BC1 modulates cellulose assembly by interacting with cellulose and affecting microfibril crystallinity.

  19. Fabrication de transistors monoelectroniques pour la detection de charge (United States)

    Richard, Jean-Philippe

    Le transistor monoelectro'nique (SET) est un candidat que l'on croyait avoir la capacite de remplacer le transistor des circuits integres actuel (MOSFET). Pour des raisons de faible gain en voltage, d'impedance de sortie elevee et de sensibilite aux fluctuations de charges, il est considere aujourd'hui qu'un hybride tirant profit des deux technologies est plus avantageux. En exploitant sa lacune d'etre sensible aux variations de charge, le SET est davantage utilise dans des applications ou la detection de charge s'avere indispensable, notamment dans les domaines de la bio-detection et de l'informatique quantique. Ce memoire presente une etude du transistor monoelectronique utilise en tant que detecteur de charge. La methode de fabrication est basee sur le procede nanodamascene developpe par Dubuc et al. [11] permettant au transistor monoelectronique de fonctionner a temperature ambiante. La temperature d'operation etant intimement liee a la geometrie du SET, la cle du procede nanodamascene reside dans le polissage chimico-mecanique (CMP) permettant de reduire l'epaisseur des SET jusqu'a des valeurs de quelques nanametres. Dans ce projet de maitrise, nous avons cependant opte pour que le SET soit opere a temperature cryogenique. Une faible temperature d'operation permet le relachement des contraintes de dimensions des dispositifs. En considerant les variations de procedes normales pouvant survenir lors de la fabrication, la temperature d'operation maximale calculee en conception s'etend de 27 K a 90 K, soit une energie de charge de 78 meV a 23 meV. Le gain du detecteur de charge etant dependant de la distance de couplage, les resultats de simulations demontrent que cette distance doit etre de 200 nm pour que la detection de charge soit optimale. Les designs concus sont ensuite fabriques sur substrat d'oxyde de silicium. Les resultats de fabrication de SET temoignent de la robustesse du procede nanodamascene. En effet, les dimensions atteintes experimentalement s

  20. Microbial cellulose wound dressing in the treatment of skin tears in the frail elderly. (United States)

    Solway, Douglas R; Consalter, Mauricio; Levinson, Dennis J


      In a randomized trial of predominantly category II and III skin tears in a population of frail elderly nursing home residents, standard wound care (24 residents) with Xeroform™ and a secondary dressing (Tegaderm™) was compared with a single application of a microbial cellulose membrane Dermafill (27 residents). Outcomes included the time to wound closure, pain reduction, and ease of use. While wound area was slightly larger in the microbial cellulose treated group, the healing time was equivalent to controls. However, pain control, ease of use, and patient and nursing staff satisfaction were superior to control with the use of the microbial cellulose wound dressing.

  1. Optimizing Extraction of Cellulose and Synthesizing Pharmaceutical Grade Carboxymethyl Sago Cellulose from Malaysian Sago Pulp

    Directory of Open Access Journals (Sweden)

    Anand Kumar Veeramachineni


    Full Text Available Sago biomass is an agro-industrial waste produced in large quantities, mainly in the Asia-Pacific region and in particular South-East Asia. This work focuses on using sago biomass to obtain cellulose as the raw material, through chemical processing using acid hydrolysis, alkaline extraction, chlorination and bleaching, finally converting the material to pharmaceutical grade carboxymethyl sago cellulose (CMSC by carboxymethylation. The cellulose was evaluated using Thermogravimetric Analysis (TGA, Infrared Spectroscopy (FTIR, X-Ray Diffraction (XRD, Differential Scanning Calorimetry (DSC and Field Emission Scanning Electronic Microscopy (FESEM. The extracted cellulose was analyzed for cellulose composition, and subsequently modified to CMSC with a degree of substitution (DS 0.6 by typical carboxymethylation reactions. X-ray diffraction analysis indicated that the crystallinity of the sago cellulose was reduced after carboxymethylation. FTIR and NMR studies indicate that the hydroxyl groups of the cellulose fibers were etherified through carboxymethylation to produce CMSC. Further characterization of the cellulose and CMSC were performed using FESEM and DSC. The purity of CMSC was analyzed according to the American Society for Testing and Materials (ASTM International standards. In this case, acid and alkaline treatments coupled with high-pressure defibrillation were found to be effective in depolymerization and defibrillation of the cellulose fibers. The synthesized CMSC also shows no toxicity in the cell line studies and could be exploited as a pharmaceutical excipient.

  2. Etude des potentialités des systèmes d'application contrôlée des gouttes (CDA pour les traitements phytosanitaires en céréaliculture (synthèse bibliographique

    Directory of Open Access Journals (Sweden)

    Ouled Taleb Salah, S.


    Full Text Available Study of the potential for the use of controlled droplet application (CDA upon cereal crops. A review. Introduction. Controlled droplet application (CDA has the advantage both of the reduction in the span of droplet size distribution and in the volume of liquid applied, in comparison with conventional hydraulic nozzles. Literature. This review investigates the potential for the use of CDA relative to hydraulic nozzles within the early stages of weed control (2-3 leaves. The studies reviewed examine spray retention, linking the droplet characteristics (size, velocity and direction of spray liquids with the architecture, density and wettability of the foliage. These studies show that the use of droplets of 300 µm, combined with an appropriate adjuvant and applied with a 60° forward-angled spray, led to the enhanced depositing of liquids on upright surfaces. Assessment of the reduced volumes applied by both application techniques was based on the mean, the variation coefficient and the deposition coverage. However, these results cannot be generalized, due to the different operative settings in which the spray application techniques were employed. Regarding the risk of drift to the side, the drift potential of droplets generated horizontally by CDA nozzles is greater than that of the conventional technique with a downward orientation of spray. The drift potential increases as the wind velocity increases and the volume median diameter (DV50 decreases. Conclusions. New settings of CDA nozzles in terms of DV50 and the direction of spray may address the challenge of precision agriculture. Innovative ways to apply pesticides, based on CDA, must be explored in order to avoid the sensitivity to wear of the teeth in spray applicators and to obtain a narrower droplet-size distribution.

  3. Effects of a cellulose mask synthesized by a bacterium on facial skin characteristics and user satisfaction

    Directory of Open Access Journals (Sweden)

    Amnuaikit T


    Full Text Available Thanaporn Amnuaikit, Toon Chusuit, Panithi Raknam, Prapaporn BoonmeDepartment of Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Songkhla, ThailandBackground: Cellulose masks obtained from natural sources such as bacteria are of interest as cosmetic devices for the treatment of dry skin because they not only improve hydration of the skin, but have low toxicity and are biodegradable. The aims of this study were to determine the in vivo effects of a cellulose mask obtained from Acetobacter xylinum on skin characteristics and to evaluate user satisfaction with the product.Methods: Thirty healthy Thai volunteers aged 21–40 years participated in the study. The volunteers were randomly separated into a control group and an experimental group. For the control group, volunteers were assigned to apply moist towels to the face for 25 minutes. For the experimental group, the volunteers were assigned to apply the masks, ie, translucent patches which could be fitted onto the face for the same period. The following week, the groups were changed over to the alternative treatment. Skin moisture, sebum, elasticity, texture, dullness, and desquamation levels were assessed using a system used for routine skin counseling before applying the trial product and five minutes after its removal. Degree of satisfaction with use of the cellulose mask was investigated using a five-point rating scale.Results: The cellulose mask increased moisture levels in the skin significantly more than moist towels (P < 0.05 after a single application. No obvious effects on other skin characteristics were found. The cellulose mask product rated around 4/5 on the satisfaction rating scale.Conclusions: A single application of the trial cellulose mask enhanced moisture uptake by facial skin. Users also reported being satisfied with the trial product.Keywords: bacterial cellulose, facial mask, skin characteristics, skin hydration, user

  4. Reactive Liftoff of Crystalline Cellulose Particles. (United States)

    Teixeira, Andrew R; Krumm, Christoph; Vinter, Katherine P; Paulsen, Alex D; Zhu, Cheng; Maduskar, Saurabh; Joseph, Kristeen E; Greco, Katharine; Stelatto, Michael; Davis, Eric; Vincent, Brendon; Hermann, Richard; Suszynski, Wieslaw; Schmidt, Lanny D; Fan, Wei; Rothstein, Jonathan P; Dauenhauer, Paul J


    The condition of heat transfer to lignocellulosic biomass particles during thermal processing at high temperature (>400 °C) dramatically alters the yield and quality of renewable energy and fuels. In this work, crystalline cellulose particles were discovered to lift off heated surfaces by high speed photography similar to the Leidenfrost effect in hot, volatile liquids. Order of magnitude variation in heat transfer rates and cellulose particle lifetimes was observed as intermediate liquid cellulose droplets transitioned from low temperature wetting (500-600 °C) to fully de-wetted, skittering droplets on polished surfaces (>700 °C). Introduction of macroporosity to the heated surface was shown to completely inhibit the cellulose Leidenfrost effect, providing a tunable design parameter to control particle heat transfer rates in industrial biomass reactors.

  5. Efficient cellulose solvent: quaternary ammonium chlorides. (United States)

    Kostag, Marc; Liebert, Tim; El Seoud, Omar A; Heinze, Thomas


    Pure quaternary tetraalkylammonium chlorides with one long alkyl chain dissolved in various organic solvents constitute a new class of cellulose solvents. The electrolytes are prepared in high yields and purity by Menshutkin quaternization, an inexpensive and easy synthesis route. The pure molten tetraalkylammonium chlorides dissolve up to 15 wt% of cellulose. Cosolvents, including N,N-dimethylacetamide (DMA), may be added in large excess, leading to a system of decreased viscosity. Contrary to the well-established solvent DMA/LiCl, cellulose dissolves in DMA/quaternary ammonium chlorides without any pretreatment. Thus, the use of the new solvent avoids some disadvantages of DMA/LiCl and ionic liquids, the most extensively employed solvents for homogeneous cellulose chemistry.

  6. Rapid saccharification for production of cellulosic biofuels. (United States)

    Lee, Dae-Seok; Wi, Seung Gon; Lee, Soo Jung; Lee, Yoon-Gyo; Kim, Yeong-Suk; Bae, Hyeun-Jong


    The economical production of biofuels is hindered by the recalcitrance of lignocellulose to processing, causing high consumption of processing enzymes and impeding hydrolysis of pretreated lignocellulosic biomass. We determined the major rate-limiting factor in the hydrolysis of popping pre-treated rice straw (PPRS) by examining cellulase adsorption to lignin and cellulose, amorphogenesis of PPRS, and re-hydrolysis. Based on the results, equivalence between enzyme loading and the open structural area of cellulose was required to significantly increase productive adsorption of cellulase and to accelerate enzymatic saccharification of PPRS. Amorphogenesis of PPRS by phosphoric acid treatment to expand open structural area of the cellulose fibers resulted in twofold higher cellulase adsorption and increased the yield of the first re-hydrolysis step from 13% to 46%. The total yield from PPRS was increased to 84% after 3h. These results provide evidence that cellulose structure is one of major effects on the enzymatic hydrolysis.

  7. Carboxymethylation of Cellulose by Microwave irradiation

    Institute of Scientific and Technical Information of China (English)

    YE; Jun


    Cellulose may be readily converted into ethers involving primary and secondary alcohol groups in each monomer unit and the glycosidic bonds. However, these reactions are rather more complicated than with simple substances, because the stereochemistry of the cellulose molecule is such that the vast majority of its hydroxyl groups form intra-chain hydrogen bonds or inter-chain hydrogen bonds with contiguous molecules. Carboxymethylcellulose (CMC) has played an important part in the commercial uses of cellulose derivatives. CMC becomes alkali and water soluble. The polarity can, in fact, be increased by introduction of ionizing groups, ie carboxymethyl group. CMC is generally produced by the reaction of alkali cellulose with chloroacetic acid.……

  8. Reactive Liftoff of Crystalline Cellulose Particles (United States)

    Teixeira, Andrew R.; Krumm, Christoph; Vinter, Katherine P.; Paulsen, Alex D.; Zhu, Cheng; Maduskar, Saurabh; Joseph, Kristeen E.; Greco, Katharine; Stelatto, Michael; Davis, Eric; Vincent, Brendon; Hermann, Richard; Suszynski, Wieslaw; Schmidt, Lanny D.; Fan, Wei; Rothstein, Jonathan P.; Dauenhauer, Paul J.


    The condition of heat transfer to lignocellulosic biomass particles during thermal processing at high temperature (>400 °C) dramatically alters the yield and quality of renewable energy and fuels. In this work, crystalline cellulose particles were discovered to lift off heated surfaces by high speed photography similar to the Leidenfrost effect in hot, volatile liquids. Order of magnitude variation in heat transfer rates and cellulose particle lifetimes was observed as intermediate liquid cellulose droplets transitioned from low temperature wetting (500-600 °C) to fully de-wetted, skittering droplets on polished surfaces (>700 °C). Introduction of macroporosity to the heated surface was shown to completely inhibit the cellulose Leidenfrost effect, providing a tunable design parameter to control particle heat transfer rates in industrial biomass reactors.

  9. Dissolution enthalpies of cellulose in ionic liquids. (United States)

    Parviainen, Helena; Parviainen, Arno; Virtanen, Tommi; Kilpeläinen, Ilkka; Ahvenainen, Patrik; Serimaa, Ritva; Grönqvist, Stina; Maloney, Thaddeus; Maunu, Sirkka Liisa


    In this work, interactions between cellulose and ionic liquids were studied calorimetrically and by optical microscopy. Two novel ionic liquids (1,5-Diazabicyclo[4.3.0]non-5-enium propionate and N-methyl-1,5-diazabicyclo[4.3.0]non-5-enium dimethyl phosphate) and 1-ethyl-3-methylimidazolium acetate-water mixtures were used as solvents. Optical microscopy served in finding the extent of dissolution and identifying the dissolution pattern of the cellulose sample. Calorimetric studies identified a peak relating to dissolution of cellulose in solvent. The transition did, however, not indicate complete dissolution, but rather dissolution inside fibre or fibrils. This method was used to study differences between four cellulose samples with different pretreatment or origins.

  10. Potential of Biosynthesized Silver Nanoparticles as Nanocatalyst for Enhanced Degradation of Cellulose by Cellulase

    Directory of Open Access Journals (Sweden)

    Bipinchandra K. Salunke


    Full Text Available Silver nanoparticles (AgNPs as a result of their excellent optical and electronic properties are promising catalytic materials for various applications. In this study, we demonstrate a novel approach for enhanced degradation of cellulose using biosynthesized AgNPs in an enzyme catalyzed reaction of cellulose hydrolysis by cellulase. AgNPs were synthesized through reduction of silver nitrate by extracts of five medicinal plants (Mentha arvensis var. piperascens, Buddleja officinalis Maximowicz, Epimedium koreanum Nakai, Artemisia messer-schmidtiana Besser, and Magnolia kobus. An increase of around twofold in reducing sugar formation confirmed the catalytic activity of AgNPs as nanocatalyst. The present study suggests that immobilization of the enzyme onto the surface of the AgNPs can be useful strategy for enhanced degradation of cellulose, which can be utilized for diverse industrial applications.

  11. Etude et proposition d’un modèle d’économie d’énergie pour les réseaux de capteurs sans fil : Application médicale sportive.




    Notre mémoire a commencé par une étude générale sur les réseaux de capteurs sans fils, qui a éclairé les différentes facettes des réseaux de capteurs ainsi que leurs caractéristiques essentielles (limitation en énergie, topologie dynamique, mobilité, etc.). Nous avons également parlé de la dimension applicative (médicale, domotique, militaire, etc.) des réseaux de capteurs en raison du lien étroit qui les lie. En effet, avec la grande variété des applications liées aux réseaux ...

  12. Étude des techniques de spectrométrie de plasma pour l'analyse de matériaux à spectres optiques complexes : application aux terres rares et aux matériaux plastiques


    Barbier, Sophie,


    The LIBS (Laser Induced Breakdown Spectroscopy) technique is an elemental analysis technique based on the use of the optical emission spectrum from a sample of laser ablation. Today, LIBS has not emerged as a technique of choice for the majority of applications, as is the case for inductive coupled plasma techniques. One of the main reasons for this is the difficulty in providing accurate quantitative measurements. So there is now a need to better understand and characterize plasmas and pheno...

  13. Analyse des performances et routage dans les constellations de nano-satellites : modèles et applications pour les régions éloignées


    Burlacu, Maria-Mihaela


    The growth in cost and complexity of traditional scientific missions along with the reduction in space budgets have determined space community to focus on small satellites that not only provide valuable scientific returns, but also allow completely new applications in remote sensing, environmental monitoring and communications. Furthermore, small satellite flying in formation is a key technology for many future space science missions, by improving mission survivability and reducing mission co...

  14. Cellulose-water interaction: a spectroscopic study


    Lindh, Erik L


    The human society of today has a significantly negative impact on the environment and needs to change its way of living towards a more sustainable path if to continue to live on a healthy planet. One path is believed to be an increased usage of naturally degradable and renewable raw materials and, therefore, attention has been focused on the highly abundant biopolymer cellulose. However, a large drawback with cellulose-based materials is the significant change of their mechanical properties w...

  15. 抗癌消水膏外敷并胸腔内灌注白细胞介素Ⅱ治疗癌性胸液临床研究%Clinical research of the treatment of using Kang ai xiao shui plaster external application and pour Interleukin-2 into chest thorax

    Institute of Scientific and Technical Information of China (English)

    庞土友; 袁学明; 王耿介; 余滨; 柯华琪; 陈海腊; 李欣


    目的:研究探讨抗癌消水膏外敷并胸腔内灌注白细胞介素Ⅱ的治疗方法对恶性肿瘤并发胸腔积液患者的治疗效果。方法:选取收治入院的癌症并发胸腔积液患者60例,并行胸腔穿刺,留置导管进行引流,将上述患者随机分为A、B两组,即A组为治疗组,B组为对照组。对B组患者除行胸腔穿刺,留置导管进行引流外,只进行肿瘤常规治疗,A组除行胸腔穿刺,留置导管进行引流外,并用抗癌消水膏外敷并胸腔内灌注白细胞介素Ⅱ的治疗。结果:治疗A组总有效率86.7%,对照B组总有效率53.4%。结论:通过考察60例治疗的总有效率,采用抗癌消水膏外敷并胸腔内灌注白细胞介素Ⅱ的治疗方法治疗恶性肿瘤并发胸腔积液,疗效肯定,是抑制恶性肿瘤并发胸腔积液的有效方法。%Objective To investigate the value of Kang ai xiao shui plaster external application and pour Interleukin-2 in treatment of patients with malignant pleural effusion. Method Select and choose 60 cancer patients with hydrothorax from Respiration medicine of both cooperative hospital and mine. By means of thoracocentesis,we used intrathoracic drain to drainage hydrothorax. Those patients into two groups. Respectively were group A and group B. Patients of the control group( group B)were treated by using intrathoracic drain to drain hydrothorax with normal cancer reament. Patients of the treatment group( group A)were treated by not only including group B but adopte external application and pour Interleukin-2. Results Total effective rate of group A was 86. 7%,total effective rate of group B was 53. 4%. Conclusion By observing the curative effective rate of 60 cases above,the authors suggest that the therapy- external application of anti-cancer Xiaoshui cream and intrathoracic infusion of interleukin II is effective to inhibit malignant tumor complicated with pleural effusion.

  16. Decodeurs rapides pour codes topologiques quantiques (United States)

    Duclos-Cianci, Guillaume

    L'encodage topologique de l'information quantique a attire beaucoup d'attention, car c'est un modele qui semble propice a resister aux erreurs locales. Tout d'abord, le modele du calcul topologique est base sur la statistique anyonique non-Abelienne universelle et sur son controle. Des anyons indesirables peuvent apparaitre soudainement, en raison de fluctuations thermiques ou de processus virtuels. La presence de ces anyons peut corrompre l'information encodee, il est necessaire de les eliminer: la correction consiste a fusionner les defauts tout en preservant la topologie du systeme. Ensuite, dans le cas des codes topologiques, on doit aussi proteger l'information encodee dans la topologie. En effet, dans ces systemes, on n'a acces qu'a une fraction de l'information decrivant l'erreur. Elle est recueillie par des mesures et peut etre interpretee en termes de particules. Ces defauts peuplent le code et doivent etre annihiles adequatement dans le but de preserver l'information encodee. Dans ce memoire, nous proposons un algorithme efficace, appele decodeur, pouvant etre utilise dans les deux contextes decrits ci-haut. Pour y parvenir, cet algorithme s'inspire de methodes de renormalisation et de propagation de croyance. Il est exponentiellement plus rapide que les methodes deja existantes, etant de complexite O (ℓ2 log ℓ) en serie et, si on parallelise, O (log ℓ) en temps, contre O (ℓ6) pour les autres decodeurs. Le temps etant le facteur limitant dans le probleme du decodage, cette caracteristique est primordiale. De plus, il tolere une plus grande amplitude de bruit que les methodes existantes; il possede un seuil de ˜ 16.5% sur le canal depolarisant surpassant le seuil deja etabli de ˜ 15.5%. Finalement, il est plus versatile. En effet, en etant limite au code de Kitaev, on ne savait pas decoder les codes topologiques de maniere generale (e.g. codes de couleur). Or, le decodeur propose dans ce memoire peut traiter la grande classe des codes

  17. Transfert radiatif numerique pour un code SPH (United States)

    Viau, Joseph Edmour Serge


    Le besoin de reproduire la formation d'etoiles par simulations numeriques s'est fait de plus en plus present au cours des 30 dernieres annees. Depuis Larson (1968), les codes de simulations n'ont eu de cesse de s'ameliorer. D'ailleurs, en 1977, Lucy introduit une autre methode de calcul venant concurrencer la methode par grille. Cette nouvelle facon de calculer utilise en effet des points a defaut d'utiliser des grilles, ce qui est une bien meilleure adaptation aux calculs d'un effondrement gravitationnel. Il restait cependant le probleme d'ajouter le transfert radiatif a un tel code. Malgre la proposition de Brookshaw (1984), qui nous montre une formule permettant d'ajouter le transfert radiatif sous la forme SPH tout en evitant la double sommation genante qu'elle implique, aucun code SPH a ce jour ne contient un transfert radiatif satisfaisant. Cette these presente pour la premiere fois un code SPH muni d'un transfert radiatif adequat. Toutes les difficultes ont pu etre surmontees afin d'obtenir finalement le transfert radiatif "vrai" qui survient dans l'effondrement d'un nuage moleculaire. Pour verifier l'integrite de nos resultats, une comparaison avec le nonisothermal test case de Boss & Myhill (1993) nous revele un resultat fort satisfaisant. En plus de suivre fidelement la courbe de l'evolution de la temperature centrale en fonction de la densite centrale, notre code est exempt de toutes les anomalies rencontrees par les codes par grille. Le test du cas de la conduction thermique nous a lui aussi servit a verifier la fiabilite de notre code. La aussi les resultats sont fort satisfaisants. Faisant suite a ces resultats, le code fut utilise dans deux situations reelles de recherche, ce qui nous a permis de demontrer les nombreuses possibilites que nous donne notre nouveau code. Dans un premier temps, nous avons tudie le comportement de la temperature dans un disque d'accretion durant son evolution. Ensuite nous avons refait en partie une experience de Bonnell

  18. Images du Mage, images pour le Mage

    Directory of Open Access Journals (Sweden)

    Daniel GREGORIO


    Full Text Available Les œuvres d’Alphonse X proposent diverses représentations du mage, qui en font, tour à tour, l’ennemi ou l’allié de la religion chrétienne. Il est vrai que parfois, comme le montre l’histoire de Simon le magicien, la pratique de la magie implique un commerce direct et néfaste avec les forces infernales. Néanmoins, les personnages de Merlin et des Rois Mages, tels qu’ils sont présentés par Alphonse X, démontrent que magie et religion peuvent cohabiter, à condition toutefois que le mage croit en la virginité de Marie et en l’Incarnation et que sa pratique magique soit bénéfique pour la communauté. Ce bénéfice requiert parfois la reconstruction de l’univers quotidien ; pour ce faire, le magicien doit savoir quand et comment utiliser des objets et des pentacles, qui lui permettront de soumettre les forces surnaturelles. Il doit donc posséder une connaissance approfondie du monde naturel et des esprits qui, conjuguée à sa foi religieuse, l’empêchera de tomber dans la démonolâtrie.Las obras alfonsíes proponen diversas aproximaciones al personaje del mago, generalmente considerado como un ser antagónico del hombre religioso. Es cierto que en algunas ocasiones, como ocurre con Simón el mago, la práctica de las artes mágicas significa un trato directo y nefasto con las fuerzas infernales. Sin embargo, personajes como Merlín o los Reyes Magos, tal y como los describe Alfonso X, subrayan una posible cohabitación entre magia y religión sin que la práctica de la una signifique la exclusión de la otra. Sólo hay que cumplir con dos condiciones : creer en la virginidad de María y que Dios se hizo hombre, y proporcionar a la comunidad un beneficio claro. Este beneficio requiere en ocasiones remodelar lo cotidiano, utilizando objetos y pentáculos, en circunstancias extremadamente determinadas, lo que implica un conocimiento exhaustivo tanto del mundo natural como del simbólico y de los espíritus. Es este

  19. A thermogravimetric analysis (TGA) method to determine the catalytic conversion of cellulose from carbon-supported hydrogenolysis process

    Energy Technology Data Exchange (ETDEWEB)

    Leal, Glauco F. [Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), C.P. 6192, 13083-970 Campinas, SP (Brazil); Institute of Chemistry of São Carlos (IQSC), University of São Paulo (USP), C.P. 780, CEP 13560-970 São Carlos, SP (Brazil); Ramos, Luiz A. [Institute of Chemistry of São Carlos (IQSC), University of São Paulo (USP), C.P. 780, CEP 13560-970 São Carlos, SP (Brazil); Barrett, Dean H. [Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), C.P. 6192, 13083-970 Campinas, SP (Brazil); Curvelo, Antonio Aprígio S. [Institute of Chemistry of São Carlos (IQSC), University of São Paulo (USP), C.P. 780, CEP 13560-970 São Carlos, SP (Brazil); Brazilian Bioethanol Science and Technology Laboratory (CTBE), Brazilian Center for Research in Energy and Materials (CNPEM), C.P. 6179, 13083-970 Campinas, SP (Brazil); Rodella, Cristiane B., E-mail: [Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), C.P. 6192, 13083-970 Campinas, SP (Brazil)


    Graphical abstract: - Highlights: • A new method to determine the catalytic conversion of cellulose using TGA has been developed. • TGA is able to differentiate between carbon from cellulose and carbon from the catalyst. • Building an analytical curve from TGA results enables the accurate determination of cellulose conversion. - Abstract: The ability to determine the quantity of solid reactant that has been transformed after a catalytic reaction is fundamental in accurately defining the conversion of the catalyst. This quantity is also central when investigating the recyclability of a solid catalyst as well as process control in an industrial catalytic application. However, when using carbon-supported catalysts for the conversion of cellulose this value is difficult to obtain using only a gravimetric method. The difficulty lies in weighing errors caused by loss of the solid mixture (catalyst and non-converted cellulose) after the reaction and/or moisture adsorption by the substrate. These errors are then propagated into the conversion calculation giving erroneous results. Thus, a quantitative method using thermogravimetric analysis (TGA) has been developed to determine the quantity of cellulose after a catalytic reaction by using a tungsten carbide catalyst supported on activated carbon. Stepped separation of TGA curves was used for quantitative analysis where three thermal events were identified: moisture loss, cellulose decomposition and CO/CO{sub 2} formation. An analytical curve was derived and applied to quantify the residual cellulose after catalytic reactions which were performed at various temperatures and reaction times. The catalytic conversion was calculated and compared to the standard gravimetric method. Results showed that catalytic cellulose conversion can be determined using TGA and exhibits lower uncertainty (±2%) when compared to gravimetric determination (±5%). Therefore, it is a simple and relatively inexpensive method to determine

  20. Utilization of biocatalysts in cellulose waste minimization

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, J.; Evans, B.R.


    Cellulose, a polymer of glucose, is the principal component of biomass and, therefore, a major source of waste that is either buried or burned. Examples of biomass waste include agricultural crop residues, forestry products, and municipal wastes. Recycling of this waste is important for energy conservation as well as waste minimization and there is some probability that in the future biomass could become a major energy source and replace fossil fuels that are currently used for fuels and chemicals production. It has been estimated that in the United States, between 100-450 million dry tons of agricultural waste are produced annually, approximately 6 million dry tons of animal waste, and of the 190 million tons of municipal solid waste (MSW) generated annually, approximately two-thirds is cellulosic in nature and over one-third is paper waste. Interestingly, more than 70% of MSW is landfilled or burned, however landfill space is becoming increasingly scarce. On a smaller scale, important cellulosic products such as cellulose acetate also present waste problems; an estimated 43 thousand tons of cellulose ester waste are generated annually in the United States. Biocatalysts could be used in cellulose waste minimization and this chapter describes their characteristics and potential in bioconversion and bioremediation processes.

  1. Biohydrogen, bioelectricity and bioalcohols from cellulosic materials

    Energy Technology Data Exchange (ETDEWEB)

    Nissila, M.


    The demand for renewable energy is increasing due to increasing energy demand and global warming associated with increasing use of fossil fuels. Renewable energy can be derived from biological production of energy carriers from cellulosic biomass. These biochemical processes include biomass fermentation to hydrogen, methane and alcohols, and bioelectricity production in microbial fuel cells (MFCs). The objective of this study was to investigate the production of different energy carriers (hydrogen, methane, ethanol, butanol, bioelectricity) through biochemical processes. Hydrogen production potential of a hot spring enrichment culture from different sugars was determined, and hydrogen was produced continuously from xylose. Cellulolytic and hydrogenic cultures were enriched on cellulose, cellulosic pulp materials, and on silage at different process conditions. The enrichment cultures were further characterized. The effect of acid pretreatment on hydrogen production from pulp materials was studied and compared to direct pulp fermentation to hydrogen. Electricity and alcohol(s) were simultaneously produced from xylose in MFCs and the exoelectrogenic and alcohologenic enrichment cultures were characterized. In the end, the energy yields obtained from different biochemical processes were determined and compared. In this study, cultures carrying out simultaneous cellulose hydrolysis and hydrogen fermentation were enriched from different sources at different operational conditions. These cultures were successfully utilized for cellulose to hydrogen fermentation in batch systems. Based on these results further research should be conducted on continuous hydrogen production from cellulosic materials.

  2. Improved cellular response of chemically crosslinked collagen incorporated hydroxyethyl cellulose/poly(vinyl) alcohol nanofibers scaffold. (United States)

    Zulkifli, Farah Hanani; Jahir Hussain, Fathima Shahitha; Abdull Rasad, Mohammad Syaiful Bahari; Mohd Yusoff, Mashitah


    The aim of this research is to develop biocompatible nanofibrous mats using hydroxyethyl cellulose with improved cellular adhesion profiles and stability and use these fibrous mats as potential scaffold for skin tissue engineering. Glutaraldehyde was used to treat the scaffolds water insoluble as well as improve their biostability for possible use in biomedical applications. Electrospinning of hydroxyethyl cellulose (5 wt%) with poly(vinyl alcohol) (15 wt%) incorporated with and without collagen was blended at (1:1:1) and (1:1) ratios, respectively, and was evaluated for optimal criteria as tissue engineering scaffolds. The nanofibrous mats were crosslinked and characterized by scanning electron microscope, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Scanning electron microscope images showed that the mean diameters of blend nanofibers were gradually increased after chemically crosslinking with glutaraldehyde. Fourier transform infrared spectroscopy was carried out to understand chemical interactions in the presence of aldehyde groups. Thermal characterization results showed that the stability of hydroxyethyl cellulose/poly(vinyl alcohol) and hydroxyethyl cellulose/poly(vinyl alcohol)/collagen nanofibers was increased with glutaraldehyde treatment. Studies on cell-scaffolds interaction were carried out by culturing human fibroblast (hFOB) cells on the nanofibers by assessing the growth, proliferation, and morphologies of cells. The scanning electron microscope results show that better cell proliferation and attachment appeared on hydroxyethyl cellulose/poly(vinyl alcohol)/collagen substrates after 7 days of culturing, thus, promoting the potential of electrospun scaffolds as a promising candidate for tissue engineering applications.

  3. Expression en termes d'énergie pour la perméabilité absolue effective. Application au calcul numérique d'écoulements diphasiques en milieu poreux Expression in Energy Terms for Absolute Effective Permeability. Application to the Numerical Computing of Two-Phase Flows in Porous Media

    Directory of Open Access Journals (Sweden)

    Njifenjou A.


    Full Text Available Le cadre de ce travail est le calcul des paramètres pétrophysiques effectifs d'un milieu poreux hétérogène pour le simulateur de réservoirs pétroliers. Après le choix d'un modèle d'écoulement dans un milieu poreux hétérogène comportant une microstructure périodique nous rappelons brièvement les grandes étapes de la méthode des échelles multiples pour l'homogénéisation de ce modèle. Cela nous conduit à la formule classique d'homogénéisation de la perméabilité absolue. Par la suite nous présentons une démarche originale permettant de passer de cette formule classique à une formule plus simple (d'un point de vue numérique s'exprimant en termes d'énergie dissipée par les forces de viscosité locales et caractérisant le milieu hétérogène périodique considéré. Nous démontrons ensuite, sous certaines hypothèses, l'égalité entre les énergies dissipées par les forces de viscosité associées respectivement à l'écoulement local et à l'écoulement macroscopique. Nous terminons par la présentation de quelques résultats numériques concernant des modèles d'écoulement diphasique incompressible. This project falls within the general framework of computing the effective petrophysical parameters characterizing a heterogeneous medium when it is considered from a macroscopic viewpoint as opposed to a description on the local scale. The concept of scale inevitably appears as soon as the concept of heterogeneity is broached. Depending on the applications planned, it is easy to define different observation scales of natural porous media. The local scale is a small in which the porous medium may be considered to be continuous, and in which the hydrodynamic equations are written for the fluid phase. At this scale, the elements making up the medium are sufficiently small porous volumes (compared to the dimensions of medium to be considered as points (in the mathematical sense, but large enough to encompass pores with

  4. Développement d'une source EUV plasma laser pour la micro-lithographie (United States)

    Segers, M.; Bougeard, M.; Caprin, E.; Ceccotti, T.; Chichmanian, F.; Descamps, D.; Haltebourg, P.; Hergott, J.-F.; Hulin, S.; Normand, D.; Schmidt, M.; Sublemontier, O.


    Le Groupe des Applications Plasma (GAP) du CEA à Saclay participe au projet national PREUVE du Réseau Micro- et Nano-Technologies. Ce projet a été lancé fin 1999 pour réunir et développer les compétences en France sur la lithographie dans l'extrême ultraviolet (LEUV). Au sein de PREUVE, notre objectif a été le développement d'une source plasma laser dans I'EUV autour de 13nm afin de contribuer à la réalisation d'un premier banc d'essai pour la lithographie (BEL) en Europe. Afin de réaliser cette source, nous utilisons un plasma émetteur qui est produit par l'interaction d'un laser de type Nd :YAG sur un jet de gouttelettes de xénon. A la fin du projet PREUVE, cette source satisfait les principales spécifications et répond en particulier aux besoins en flux de photons EUV pour réaliser des tests d'insolation EUV avec le banc d'essai. Suite à ces résultats prometteurs, nous démarrons actuellement un projet industriel EXULITE avec nos partenaires du CEA, d'Alcatel et de Thalès sur le développement d'une source EUV de puissance pour des machines de lithographie de production. Ce projet se terminera en 2005.

  5. Prévention de l’oxydation des acides gras dans un produit cosmétique : mécanismes, conséquences, moyens de mesure, quels antioxydants pour quelles applications ?

    Directory of Open Access Journals (Sweden)

    Judde Armelle


    Full Text Available To recall the general mechanism of fatty acid oxidation, a focus is made on the different degradation product families and their impact on the quality of blend or formulated fats and oils. Because of the importance of the analytical method choice to assess the oxidative status of the products, a review underlines the precautions required to interpret the results. Another important point concerns the Good Manufacturing Practices to reduce the oxidative risk, and the respective advantages and drawbacks of a selection of synthetic or natural antioxidants in cosmetic applications, conclude this short review.

  6. Oxydes transparents conducteurs et convertisseurs de photons pour des applications photovoltaïques : les cas de l'oxyde de zinc et de l'oxyde de cérium dopés aux terres rares


    Balestrieri, Matteo


    The objective of this thesis was to investigate the photon converting properties of rare earths (RE) ions embedded in transparent oxide hosts in view of potential application on silicon solar cells. In particular, the goal was to functionalize thin films that are already used in solar cells such as anti-Reflection coatings or transparent conductive oxides.Two host materials (ZnO and CeO2) have been selected, which are compatible with silicon solar cells.This work shows that RE-Doped transpare...

  7. Effet de taille et du dopage sur la structure, les transitions et les propriétés optiques de particules du multiferroïque BiFeO₃ pour des applications photocatalytiques


    Bai, Xiaofei


    This experimental PhD work has been dedicated to the synthesis, by wet chemistry methods, and characterization of nanoparticles based on multiferroic BiFeO3, with the aim of using them for photocatalytic applications. This material presents a bandgap of 2.6eV, which allows the charge carrier photoexcitation in the visible range, making BiFeO3 a very interesting system for photoinduced processes. This thesis has been particularly focused on characterizing the properties of BiFeO3 nanoparticles...

  8. Synthesis and properties of regenerated cellulose-based hydrogels with high strength and transparency for potential use as an ocular bandage

    Energy Technology Data Exchange (ETDEWEB)

    Patchan, M. [Research and Exploratory Development Department, The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Graham, J.L. [Department of Biomedical Engineering, Johns Hopkins University, School of Medicine, 720 Rutland Avenue/Ross 720, Baltimore, MD 21205 (United States); Xia, Z.; Maranchi, J.P. [Research and Exploratory Development Department, The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); McCally, R. [Research and Exploratory Development Department, The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Wilmer Eye Institute, Johns Hopkins Medical Institutions, 600 N. Wolfe Street, Baltimore, MD 21287 (United States); Schein, O. [Wilmer Eye Institute, Johns Hopkins Medical Institutions, 600 N. Wolfe Street, Baltimore, MD 21287 (United States); Elisseeff, J.H. [Department of Biomedical Engineering, Johns Hopkins University, School of Medicine, 720 Rutland Avenue/Ross 720, Baltimore, MD 21205 (United States); Trexler, M.M., E-mail: [Research and Exploratory Development Department, The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States)


    Cellulose is a biologically derived material with excellent wound-healing properties. The high strength of cellulose fibers and the ability to synthesize gels with high optical transparency make these materials suitable for ocular applications. In this study, cellulose materials derived from wood pulp, cotton, and bacterial sources were dissolved in lithium chloride/N,N-dimethylacetamide to form regenerated cellulose hydrogels. Material properties of the resulting hydrogels, including water content, optical transparency, and tensile and tear strengths, were evaluated. Synthesis parameters, including activation time, dissolution time, relative humidity, and cellulose concentration, were found to impact the material properties of the resulting hydrogels. Overnight activation time improves the optical transparency of the hydrogels from 77% to 97% at 550 nm, whereas controlling cellulose concentration improves their tear strength by as much as 200%. On the basis of the measured transmittance and strength values of the regenerated hydrogels prepared via the optimized synthesis parameters, Avicel PH 101, Sigma-Aldrich microcrystalline cellulose 435236, and bacterial cellulose types were prioritized for future biocompatibility testing and potential clinical investigation. - Highlights: • Hydrogels were prepared (via LiCl/DMAc) from 7 different types of cellulose. • Synthesis parameters (activation, gelation, and concentration) were optimized. • Impact of synthesis parameters on transparency and strength was explored.

  9. Un ticket pour la liberté

    Directory of Open Access Journals (Sweden)

    Nabil Mouline


    Full Text Available Pour diverses raisons, l’industrie cinématographique égyptienne a connu des changements profonds au début des années 2000. L’une des conséquences les plus palpables a été la production de manière volontaire ou involontaire de films contestataires dans la mesure où ils essaient de remettre en cause le discours dominant et de lever le tabou sur plusieurs questions sociopolitiques. Cela a fait du produit filmique non seulement un document d’archive qui reflète l’état de la société mais également un outil efficace de soft influence et de mobilisation qui a participé à la création d’une communauté imaginée dont une partie est passée à l’action le 25 janvier 2011. C’est l’ambition de cet article que de lever le voile sur ce double rôle du cinéma entre 2001 et 2010 en s’appuyant sur un large échantillon de films à grand succès.


    Directory of Open Access Journals (Sweden)



    Full Text Available On sait qu’une courbe algébrique standard  d'équation f(x, y =0 admet un nombre fini de branches (nombre inférieur à l'ordre de f , dont les paramètrages peuvent être obtenus en particulier à partir de la décomposition de Goze itérée. On aimerait calculer  leur courbure généralisée sans les déterminer explicitement, la notion de courbure généralisée ayant fait l’objet d’un travail, publié dans les comptes rendus de l’Université de Cagliari (Italie [12]. Dans cet article, on se propose d'établir à cet effet un algorithme qui donnera à partir seulement des coefficients de f, la liste exhaustive des courbures généralisées de toutes les branches réelles. L’article se termine par la donnée d’un exemple pour montrer l’efficacité de l’algorithme proposé.

  11. Biocompatible Bacterial Cellulose-Poly(2-hydroxyethyl methacrylate Nanocomposite Films

    Directory of Open Access Journals (Sweden)

    Andrea G. P. R. Figueiredo


    Full Text Available A series of bacterial cellulose-poly(2-hydroxyethyl methacrylate nanocomposite films was prepared by in situ radical polymerization of 2-hydroxyethyl methacrylate (HEMA, using variable amounts of poly(ethylene glycol diacrylate (PEGDA as cross-linker. Thin films were obtained, and their physical, chemical, thermal, and mechanical properties were evaluated. The films showed improved translucency compared to BC and enhanced thermal stability and mechanical performance when compared to poly(2-hydroxyethyl methacrylate (PHEMA. Finally, BC/PHEMA nanocomposites proved to be nontoxic to human adipose-derived mesenchymal stem cells (ADSCs and thus are pointed as potential dry dressings for biomedical applications.

  12. Biocompatible Bacterial Cellulose-Poly(2-hydroxyethyl methacrylate) Nanocomposite Films (United States)

    Figueiredo, Andrea G. P. R.; Figueiredo, Ana R. P.; Alonso-Varona, Ana; Fernandes, Susana C. M.; Palomares, Teodoro; Rubio-Azpeitia, Eva; Barros-Timmons, Ana; Silvestre, Armando J. D.; Pascoal Neto, Carlos; Freire, Carmen S. R.


    A series of bacterial cellulose-poly(2-hydroxyethyl methacrylate) nanocomposite films was prepared by in situ radical polymerization of 2-hydroxyethyl methacrylate (HEMA), using variable amounts of poly(ethylene glycol) diacrylate (PEGDA) as cross-linker. Thin films were obtained, and their physical, chemical, thermal, and mechanical properties were evaluated. The films showed improved translucency compared to BC and enhanced thermal stability and mechanical performance when compared to poly(2-hydroxyethyl methacrylate) (PHEMA). Finally, BC/PHEMA nanocomposites proved to be nontoxic to human adipose-derived mesenchymal stem cells (ADSCs) and thus are pointed as potential dry dressings for biomedical applications. PMID:24093101

  13. Versatile Molding Process for Tough Cellulose Hydrogel Materials. (United States)

    Kimura, Mutsumi; Shinohara, Yoshie; Takizawa, Junko; Ren, Sixiao; Sagisaka, Kento; Lin, Yudeng; Hattori, Yoshiyuki; Hinestroza, Juan P


    Shape-persistent and tough cellulose hydrogels were fabricated by a stepwise solvent exchange from a homogeneous ionic liquid solution of cellulose exposure to methanol vapor. The cellulose hydrogels maintain their shapes under changing temperature, pH, and solvents. The micrometer-scale patterns on the mold were precisely transferred onto the surface of cellulose hydrogels. We also succeeded in the spinning of cellulose hydrogel fibers through a dry jet-wet spinning process. The mechanical property of regenerated cellulose fibers improved by the drawing of cellulose hydrogel fibers during the spinning process. This approach for the fabrication of tough cellulose hydrogels is a major advance in the fabrication of cellulose-based structures with defined shapes.

  14. Reinforcement of all-cellulose nanocomposite films using native cellulose nanofibrils. (United States)

    Zhao, Jiangqi; He, Xu; Wang, Yaru; Zhang, Wei; Zhang, Xinxing; Zhang, Xiaodan; Deng, Yulin; Lu, Canhui


    All-cellulose nanocomposite films were prepared using native cellulose nanofibrils (CNFs) as fillers and lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) dissolved regenerated cellulose as the matrix. The CNFs, with diameters in the range of 15-40 nm were obtained by combined physical methods of ultrasonic treatment and high shear homogenization. The morphology, structure, and properties of the nanocomposite films were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), optical transmittance, thermal gravimetric analysis (TGA), and mechanical testing. The nanocomposite films exhibited good optical transparency, thermal stability, and remarkably enhanced mechanical properties compared to the regenerated cellulose matrix. By varying the CNFs content, the tensile strength of the nanocomposite films increased from 61.56 MPa to 99.92 MPa and the Young's modulus increased from 0.76 GPa to 4.16 GPa. This work provided a promising pathway for manufacturing high performance and environmental-friendly all-cellulose nanocomposites.

  15. Laser cleaning of particulates from paper: Comparison between sized ground wood cellulose and pure cellulose (United States)

    Arif, S.; Kautek, W.


    Visible laser cleaning of charcoal particulates from yellow acid mechanical ground wood cellulose paper was compared with that from bleached sulphite softwood cellulose paper. About one order of magnitude of fluence range is available for a cleaning dynamics between the cleaning threshold and the destruction threshold for two laser pulses. Wood cellulose paper exhibited a higher destruction threshold of the original paper than that of the contaminated specimen because of heat transfer from the hot or evaporating charcoal particulates. In contrast, the contaminated bleached cellulose paper exhibited a higher destruction threshold due to shading by the particulates. The graphite particles are not only detached thermo-mechanically, but also by evaporation or combustion. A cleaning effect was found also outside the illuminated areas due to lateral blasting. Infrared measurements revealed dehydration/dehydrogenation reactions and cross-links by ether bonds together with structural changes of the cellulose chain arrangement and the degree of crystallinity.

  16. Cellulose ethanol is ready to go

    Energy Technology Data Exchange (ETDEWEB)

    Hladik, M. [Iogen Corp., Ottawa, ON (Canada)


    Ottawa-based Iogen Corporation is a leader in industrial biotechnology with a focus on cellulose-based enzyme technology. The company designed and operates the world's first and largest cellulose ethanol demonstration facility making ethanol from biomass. This presentation described Iogen's cellulose ethanol demonstration facility and outlined the innovative process in which enzymes prepare the plant fibres for fermentation, distillation and finally conversion to cellulose ethanol fuel. Hydrolysis and fermentation are achieved using a multi-stage hydrolysis process. It is anticipated that biorefineries will use the residues from locally grown agriculture to produce the ethanol, but stakeholder alliances will have to be built in order to form the elements of commercialization. Feedstocks, government policy, infrastructure issues, investment climate and ethanol sales all contribute to the success of a commercial plant. An assessment of preliminary global feedstock availability was presented with reference to total wheat, coarse grains, barley, oats, rye, sorghum, rice straw and sugar cane production. To date, the use of cellulose ethanol fuel has been demonstrated in vehicle trials in Bonn, Germany, as well as fleet vehicles operated by Natural Resources Canada and Agriculture Canada. Sample feedstock basins in Germany, Canada and the United States were highlighted. The supply of cellulose feedstock is large enough to contribute significantly to reductions in fossil fuel consumption. The United States Department of Energy claims that cellulose ethanol could displace over 30 per cent of the current petroleum consumption in the United States, and that land resources in the United States are capable of producing a sustainable supply of biomass. However, technology, financing and government policies are the factors which currently affect the commercialization of emerging technologies. tabs., figs.

  17. Production of Cellulosic Polymers from Agricultural Wastes

    Directory of Open Access Journals (Sweden)

    A. U. Israel


    Full Text Available Cellulosic polymers namely cellulose, di-and triacetate were produced from fourteen agricultural wastes; Branch and fiber after oil extraction from oil palm (Elais guineensis, raffia, piassava, bamboo pulp, bamboo bark from raphia palm (Raphia hookeri, stem and cob of maize plant (Zea mays, fruit fiber from coconut fruit (Cocos nucifera, sawdusts from cotton tree (Cossypium hirsutum, pear wood (Manilkara obovata, stem of Southern gamba green (Andropogon tectorus, sugarcane baggase (Saccharium officinarum and plantain stem (Musa paradisiaca. They were subjected to soda pulping and hypochlorite bleaching system. Results obtained show that pulp yield from these materials were: 70.00, 39.59, 55.40, 86.00, 84.60, 80.00, 40.84, 81.67, 35.70, 69.11, 4.54, 47.19, 31.70 and 52.44% respectively. The pulps were acetylated with acetic anhydride in ethanoic acid catalyzed by conc. H2SO4 to obtain cellulose derivatives (Cellulose diacetate and triacetate. The cellulose diacetate yields were 41.20, 17.85, 23.13, 20.80, 20.23, 20.00, 39.00, 44.00, 18.80, 20.75, 20.03, 41.20, 44.00, and 39.00% respectively while the results obtained as average of four determinations for cellulose triacetate yields were: 52.00, 51.00, 43.10, 46.60, 49.00, 35.00, 40.60, 54.00, 57.50, 62.52, 35.70. 52.00, 53.00 and 38.70% respectively for all the agricultural wastes utilized. The presence of these cellulose derivatives was confirmed by a solubility test in acetone and chloroform.

  18. Lyocell Fiber-Reinforced Cellulose Ester Composites-Manufacturing Considerations and Properties.



    Biodegradable thermoplastic composites were prepared using high modulus lyocell fibers and cellulose acetate butyrate (CAB). Two reinforcement fiber types: fabric and continuous fiber tow were used. Fabric had advantages of uniform alignment and easier processing, but lacked the use as a unidirectional reinforcement and a continuous method of matrix application. Three different matrix application methods were screened for both fiber types. Matrix application by suspension of particles in wate...

  19. Applications des marqueurs moléculaires dans l'amélioration du blé tendre pour la résistance aux maladies et aux insectes

    Directory of Open Access Journals (Sweden)

    El Jaafari S.


    Full Text Available Applications of molecular markers in bread wheat breeding for pest and disease resistance. The development in recent years of DNAmarkers offers the possibility of developing new approaches to improving the efficiency of selection strategies. The molecular markers are becoming essential tools in bread wheat (Triticum aestivum L. breeding since they offer alternative solutions to many breeding problems resulting from the traditional phenotypic markers that are difficult and/or time-consuming to select by plant breeders. Availability of tightly linked molecular markers can now be used in markerassisted selection (MAS programs, specially for disease and pest resistance gene where it is possible to infer the gene by the marker without depending on the natural pest or pathogen occurrence or waiting for its phenotypic expression. Moreover, these markers have potential importance in facilitating selection procedure, particularly for pyramiding two or more different genes aiming at a more durable and broad- spectrum resistance. Breeding for disease and pest resistance gene can contribute to improving quality yield in wheat plants by carrying out indirect selection through molecular markers linked to the traits of interest. We first provide a brief description of main molecular markers technologies currently being employed. Next, we review some of the current and potential uses of molecular markers in breeding for disease and pest resistance genes in bread wheat

  20. Development of ODS ferritic-martensitic steels for application to high temperature and irradiation environment; Developpement d'une nouvelle nuance martensitique ODS pour utilisation sous rayonnement a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lambard, V


    Iron oxide dispersion strengthened alloys are candidate for nuclear fuel cladding. Therefore, it is crucial to control their microstructure in order to optimise their mechanical properties at temperatures up to 700 deg C. The industrial candidates, ODS ferritic alloys, present an anisotropic microstructure which induces a weakening of mechanical properties in transversal direction as well as the precipitation of brittle phases under thermal aging and irradiation. For this purpose, we tried to develop a material with isotropic properties. We studied several 9Cr-1Mo ferritic/martensitic alloys, strengthened or not by oxide dispersion. The mechanical alloying was performed by attribution and powders were consolidated by hot extrusion. In this work, different metallurgical characterisation techniques and modelling were used to optimise a new martensitic ODS alloy. Microstructural and chemical characterization of matrix has been done. The effect of austenitizing and isochronal tempering treatments on microstructure and hardness has been studied. Oxide distribution, size and chemical composition have been studied before and after high temperature thermal treatment. The study of phase transformation upon heating has permitted the extrapolation to the equilibrium temperature formation of austenite. Phase transformation diagrams upon cooling have been determined and the transformation kinetics have been linked to austenite grain size by a simple relation. Fine grain size is unfavourable for the targeted application, so a particular thermal treatment inducing a coarser grain structure has been developed. Finally, tensile properties have been determined for the different microstructures. (author)

  1. Elaboration of massive silicon carbide monocrystals for power electronics applications. Reduction of the density of defects; Elaboration de monocristaux de carbure de silicium massifs pour l'electronique de puissance - reduction de la densite de defauts

    Energy Technology Data Exchange (ETDEWEB)

    Moulin, C. [CEA Grenoble, LETI, 38 - Grenoble (France)


    Thanks to its exceptional physical properties, SiC is a semiconductor material of prime importance for average and high power, high frequency and high temperature electronic applications. However, the SiC technology requires large diameter substrates (50 mm) with a density of micro-defects (micro-pipes or micro-tubes) lower than 10/cm{sup 2}. The present study deals with the reduction of the defects density in massive SiC crystals elaborated using a modified version of Lely's method. The method consists in the sublimation of a SiC powder and to the condensation of vapor species onto a SiC monocrystal germ. A thermal gradient is established between the powder and the germ which favors the transport of species from the powder to the germ. A study of the crystals characteristics and of the growth properties has permitted to identify the sensible parameters and to significantly improve the quality of the obtained crystals. Short note. (J.S.)

  2. Isolation and characterization of two cellulose morphology mutants of Gluconacetobacter hansenii ATCC23769 producing cellulose with lower crystallinity.

    Directory of Open Access Journals (Sweden)

    Ying Deng

    Full Text Available Gluconacetobacter hansenii, a Gram-negative bacterium, produces and secrets highly crystalline cellulose into growth medium, and has long been used as a model system for studying cellulose synthesis in higher plants. Cellulose synthesis involves the formation of β-1,4 glucan chains via the polymerization of glucose units by a multi-enzyme cellulose synthase complex (CSC. These glucan chains assemble into ordered structures including crystalline microfibrils. AcsA is the catalytic subunit of the cellulose synthase enzymes in the CSC, and AcsC is required for the secretion of cellulose. However, little is known about other proteins required for the assembly of crystalline cellulose. To address this question, we visually examined cellulose pellicles formed in growth media of 763 individual colonies of G. hansenii generated via Tn5 transposon insertion mutagenesis, and identified 85 that produced cellulose with altered morphologies. X-ray diffraction analysis of these 85 mutants identified two that produced cellulose with significantly lower crystallinity than wild type. The gene disrupted in one of these two mutants encoded a lysine decarboxylase and that in the other encoded an alanine racemase. Solid-state NMR analysis revealed that cellulose produced by these two mutants contained increased amounts of non-crystalline cellulose and monosaccharides associated with non-cellulosic polysaccharides as compared to the wild type. Monosaccharide analysis detected higher percentages of galactose and mannose in cellulose produced by both mutants. Field emission scanning electron microscopy showed that cellulose produced by the mutants was unevenly distributed, with some regions appearing to contain deposition of non-cellulosic polysaccharides; however, the width of the ribbon was comparable to that of normal cellulose. As both lysine decarboxylase and alanine racemase are required for the integrity of peptidoglycan, we propose a model for the role of

  3. Oxidized cellulose dressings for persistent bleeding from a superficial malignant tumor. (United States)

    Lagman, Ruth; Walsh, Declan; Day, Kathy


    Persistent bleeding from superficial malignant tumors, although uncommon, can be a major and distressing problem. Management includes frequent skilled dressing changes, correction of clotting abnormalities, and maintaining blood volume by repeated transfusions. We report a case where application of oxidized regenerated cellulose surgical dressing appeared to contribute to successful hemostasis.

  4. Deux comparatismes pour une anthropologie historique

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    Pierre-Olivier Dittmar


    Full Text Available Malgré des appels répétés depuis plus d’un siècle de la part des historiens, le comparatisme, qui est un élément majeur de l’anthropologie, demeure très peu pratiqué. Ce rejet est ici analysé comme un refus d’une quête des invariants de l’homme qui aboutirait à des résultats an-historiques. Un autre comparatisme est cependant possible, qui instrumentalise la confrontation des univers pour mieux relever les différences. C’est les conditions et les avantages d’une telle pratique qui sont ici exposés, à partir de l’exemple des tabous alimentaires.Despite the repeated calls by some historians for more than a century, many seldom practice a major element of anthropology: comparativism. This paper will analyze this rejection as a refusal to investigate the constants of the human experience that lead to a-historical conclusions. However, another kind of comparativism is possible, one that examines the contrast between cultures in order to better understand their differences. Using the case of dietary taboos, this paper will look at the conditions and advantages of such a practice.Nonostante i molteplici appelli da più di un secolo da parte degli storici, il comparatismo, che costituisce un elemento fondamentale dell’antropologia, è ancora oggi troppo poco spesso praticato. Si proporrà di interpretare questo rifiuto come un rifiuto della ricerca di invarianti umane che condurrebbe a risultati a-storici. Un’altra forma di comparatismo è nondimeno possibile, una forma precisamente che ricorre al confronto di universi diversi per meglio comprenderne le difference reciproche. L’articolo espone le condizioni e i vantaggi di questa metodologia di ricerca, a partire dall’esempio degli interdetti alimentari.

  5. Isolation of Cellulose Nanofibers: Effect of Biotreatment on Hydrogen Bonding Network in Wood Fibers

    Directory of Open Access Journals (Sweden)

    Sreekumar Janardhnan


    Full Text Available The use of cellulose nanofibres as high-strength reinforcement in nano-biocomposites is very enthusiastically being explored due to their biodegradability, renewability, and high specific strength properties. Cellulose, through a regular network of inter- and intramolecular hydrogen bonds, is organized into perfect stereoregular configuration called microfibrils which further aggregate to different levels to form the fibre. Intermolecular hydrogen bonding at various levels, especially at the elementary level, is the major binding force that one need to overcome to reverse engineer these fibres into their microfibrillar level. This paper briefly describes a novel enzymatic fibre pretreatment developed to facilitate the isolation of cellulose microfibrils and explores effectiveness of biotreatment on the intermolecular and intramolecular hydrogen bonding in the fiber. Bleached Kraft Softwood Pulp was treated with a fungus (OS1 isolated from elm tree infected with Dutch elm disease. Cellulose microfibrils were isolated from these treated fibers by high-shear refining. The % yield of nanofibres and their diameter distribution (<50 nm isolated from the bio-treated fibers indicated a substantial increase compared to those isolated from untreated fibers. FT-IR spectral analysis indicated a reduction in the density of intermolecular and intramolecular hydrogen bonding within the fiber. X-ray spectrometry indicated a reduction in the crystallinity. Hydrogen bond-specific enzyme and its application in the isolation of new generation cellulose nano-fibers can be a huge leap forward in the field of nano-biocomposites.

  6. Aqueous Modification of Nano- and Microfibrillar Cellulose with a Click Synthon. (United States)

    Hettegger, Hubert; Beaumont, Marco; Potthast, Antje; Rosenau, Thomas


    The modification of cellulose as a renewable resource has received wide attention in research and industry. A major problem regarding chemical modification, including heating and drying, is related to hornification that causes pore-system collapse and results in decreased reactivity and changes in the 3D structure of the material. A mild and green approach for the modification of different never-dried and thus wet cellulose substrates (pulp, nanostructured celluloses, and viscose fibers) by an alkoxysilane-azide in water is presented. A kinetic study of the silanization reaction demonstrates that alkoxy-trans-silanization of the cellulose surface is accomplished in water as a suspension medium within a few hours at room temperature. The resulting, azido-equipped celluloses are widely applicable precursor materials for subsequent functionalization by so-called click chemistry, for example, with a fluorescent Rhodamine derivative as a representative reagent. Successful covalent bonding was shown by GPC and a model reaction. The 3D structure of the materials remained intact, as was inter alia visualized by optical and fluorescence microscopy.

  7. The biodegradability and nontoxicity of carboxymethyl cellulose (DS 0.7) and intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Ginkel, C.G. van; Gayton, S. [Akzo Nobel Central Research, Arnhem (Netherlands)


    Carboxymethyl cellulose with a DS ranging from 0.4 to 1.3 has become the largest industrial cellulose ether because of tis versatile applications in, for example, detergents and oil drilling. Carboxymethyl cellulose (CMC) with a degree of substitution of 0.7 is a water-soluble polymer. In some cases, CMC ends up in wastewater treatment plants and, ultimately, in the environment. Carboxymethyl cellulose degrades completely at low rates in the environment as demonstrated in a prolonged closed bottle test and in a semicontinuous activated sludge test. The continuous-flow activated sludge (CAS) test simulates sewage treatment plants. In the CAS test the CMC added to raw sewage prior to entering the bioreactor was partly biodegraded by microorganisms. The effluent from the reactor containing intermediates was then used in standard aquatic toxicity tests. No toxicity was shown in the effluent, which indicates that the intermediates formed by biodegradation are not toxic. Carboxymethyl cellulose intermediates produced by a pure culture of a CMC-degrading bacterium were also shown not to be toxic, because no effects were observed at the highest concentrations tested: 0.5 g/L for Selenastrum capricornutum (algae), 1.0 g/L for Daphnia magna (water flea), and 1.0 g/L for Brachydanio rerio (zebra fish). In addition, the nontoxicity of CMC to these aquatic organisms was established with no-effect concentrations of > 0.5 g/L.

  8. Visualising recalcitrance by colocalisation of cellulase, lignin and cellulose in pretreated pine biomass using fluorescence microscopy (United States)

    Donaldson, Lloyd; Vaidya, Alankar


    Mapping the location of bound cellulase enzymes provides information on the micro-scale distribution of amenable and recalcitrant sites in pretreated woody biomass for biofuel applications. The interaction of a fluorescently labelled cellulase enzyme cocktail with steam-exploded pine (SEW) was quantified using confocal microscopy. The spatial distribution of Dylight labelled cellulase was quantified relative to lignin (autofluorescence) and cellulose (Congo red staining) by measuring their colocalisation using Pearson correlations. Correlations were greater in cellulose-rich secondary cell walls compared to lignin-rich middle lamella but with significant variations among individual biomass particles. The distribution of cellulose in the pretreated biomass accounted for 30% of the variation in the distribution of enzyme after correcting for the correlation between lignin and cellulose. For the first time, colocalisation analysis was able to quantify the spatial distribution of amenable and recalcitrant sites in relation to the histochemistry of cellulose and lignin. This study will contribute to understanding the role of pretreatment in enzymatic hydrolysis of recalcitrant softwood biomass. PMID:28281670

  9. Visualising recalcitrance by colocalisation of cellulase, lignin and cellulose in pretreated pine biomass using fluorescence microscopy (United States)

    Donaldson, Lloyd; Vaidya, Alankar


    Mapping the location of bound cellulase enzymes provides information on the micro-scale distribution of amenable and recalcitrant sites in pretreated woody biomass for biofuel applications. The interaction of a fluorescently labelled cellulase enzyme cocktail with steam-exploded pine (SEW) was quantified using confocal microscopy. The spatial distribution of Dylight labelled cellulase was quantified relative to lignin (autofluorescence) and cellulose (Congo red staining) by measuring their colocalisation using Pearson correlations. Correlations were greater in cellulose-rich secondary cell walls compared to lignin-rich middle lamella but with significant variations among individual biomass particles. The distribution of cellulose in the pretreated biomass accounted for 30% of the variation in the distribution of enzyme after correcting for the correlation between lignin and cellulose. For the first time, colocalisation analysis was able to quantify the spatial distribution of amenable and recalcitrant sites in relation to the histochemistry of cellulose and lignin. This study will contribute to understanding the role of pretreatment in enzymatic hydrolysis of recalcitrant softwood biomass.

  10. Thin-film Nanofibrous Composite Membranes Containing Cellulose or Chitin Barrier Layers Fabricated by Ionic Liquids

    Energy Technology Data Exchange (ETDEWEB)

    H Ma; B Hsiao; B Chu


    The barrier layer of high-flux ultrafiltration (UF) thin-film nanofibrous composite (TFNC) membranes for purification of wastewater (e.g., bilge water) have been prepared by using cellulose, chitin, and a cellulose-chitin blend, regenerated from an ionic liquid. The structures and properties of regenerated cellulose, chitin, and a cellulose-chitin blend were analyzed with thermogravimetric analysis (TGA) and wide-angle X-ray diffraction (WAXD). The surface morphology, pore size and pore size distribution of TFNC membranes were determined by SEM images and molecular weight cut-off (MWCO) methods. An oil/water emulsion, a model of bilge water, was used as the feed solution, and the permeation flux and rejection ratio of the membranes were investigated. TFNC membranes based on the cellulose-chitin blend exhibited 10 times higher permeation flux when compared with a commercial UF membrane (PAN10, Sepro) with a similar rejection ratio after filtration over a time period of up to 100 h, implying the practical feasibility of such membranes for UF applications.

  11. Comment on Shvedova et al. (2016), "gender differences in murine pulmonary responses elicited by cellulose nanocrystals". (United States)

    Shatkin, Jo Anne; Oberdörster, Günter


    A recent publication in "Particle and Fibre Toxicology" reported on the gender differences in pulmonary toxicity from oro-pharyngeal aspiration of a high dose of cellulose nanocrystals. The study is timely given the growing interest in diverse commercial applications of cellulose nanomaterials, and the need for studies addressing pulmonary toxicity. The results from this study are interesting and can be strengthened with a discussion of how differences in the weights of female and male C57BL/6 mice was accounted for. Without such a discussion, the observed differences could be partially explained by the lower body weights of females, resulting in higher doses than males when standardized to body weight or lung volume. Further, few conclusions can be drawn about the pulmonary toxicity of cellulose nanocrystals given the study design: examination of a single high dose of cellulose nanocrystals, administered as a bolus, without positive or negative controls or low dose comparisons, and at an unphysiological and high dose rate. Simulating the bolus type delivery by inhalation would require a highly unrealistic exposure concentration in the g/m(3) range of extremely short duration. A discussion of these limitations is missing in the paper; further speculative comparisons of cellulose nanocrystals toxicity to asbestos and carbon nanotubes in the abstract are both unwarranted and can be misleading, these materials were neither mentioned in the manuscript, nor evaluated in the study.

  12. Biogenic nanosilica blended by nanofibrillated cellulose as support for slow-release of tebuconazole (United States)

    Mattos, Bruno D.; Magalhães, Washington L. E.


    Despite the potential application of nanotechnology in the agricultural sector, it is not as competitive as other industrial sectors because these approaches do not demonstrate a sufficient economic return to counterbalance the high production costs. For biocidal purposes, the reduction of the initial costs can be addressed if biogenic nanosilica and nanofibrillated cellulose were used to prepare nanocomposite for further utilization as support for slow-release of tebuconazole. Infrared spectroscopy and thermogravimetric analysis revealed that biocide was entrapped in the cellulose/silica nanocomposites network. The scanning electron microscopy and X-ray microtomography evaluation showed the nanocomposite's microstructure based on irregular shape nanosilica blended by nanofibrillated cellulose in a randomly organized network. Elemental mapping images showed the tebuconazole better dispersed in the composite blended with lower content of cellulose. The nanofibrillated cellulose played an important role in the release rate of the biocide mainly at short-term periods. At 15 days of immersion, the pure biocide had 95 % release compared with 30-45 % release of the tebuconazole loaded in the nanocomposites.

  13. Suite of Activity-Based Probes for Cellulose-Degrading Enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Chauvigne-Hines, Lacie M.; Anderson, Lindsey N.; Weaver, Holly M.; Brown, Joseph N.; Koech, Phillip K.; Nicora, Carrie D.; Hofstad, Beth A.; Smith, Richard D.; Wilkins, Michael J.; Callister, Stephen J.; Wright, Aaron T.


    Microbial glycoside hydrolases play a dominant role in the biochemical conversion of cellulosic biomass to high-value biofuels. Anaerobic cellulolytic bacteria are capable of producing multicomplex catalytic subunits containing cell-adherent cellulases, hemicellulases, xylanases, and other glycoside hydrolases to facilitate the degradation of highly recalcitrant cellulose and other related plant cell wall polysaccharides. Clostridium thermocellum is a cellulosome producing bacterium that couples rapid reproduction rates to highly efficient degradation of crystalline cellulose. Herein, we have developed and applied a suite of difluoromethylphenyl aglycone, N-halogenated glycosylamine, and 2-deoxy-2-fluoroglycoside activity-based protein profiling (ABPP) probes to the direct labeling of the C. thermocellum cellulosomal secretome. These activity-based probes (ABPs) were synthesized with alkynes to harness the utility and multimodal possibilities of click chemistry, and to increase enzyme active site inclusion for LC-MS analysis. We directly analyzed ABP-labeled and unlabeled global MS data, revealing ABP selectivity for glycoside hydrolase (GH) enzymes in addition to a large collection of integral cellulosome-containing proteins. By identifying reactivity and selectivity profiles for each ABP, we demonstrate our ability to widely profile the functional cellulose degrading machinery of the bacterium. Derivatization of the ABPs, including reactive groups, acetylation of the glycoside binding groups, and mono- and disaccharide binding groups, resulted in considerable variability in protein labeling. Our probe suite is applicable to aerobic and anaerobic cellulose degrading systems, and facilitates a greater understanding of the organismal role associated within biofuel development.

  14. A Suite of Activity-Based Probes for Cellulose Degrading Enzymes (United States)

    Chauvigné-Hines, Lacie M.; Anderson, Lindsey N.; Weaver, Holly M.; Brown, Joseph N.; Koech, Phillip K.; Nicora, Carrie D.; Hofstad, Beth A.; Smith, Richard D.; Wilkins, Michael J.; Callister, Stephen J.; Wright, Aaron T.


    Microbial glycoside hydrolases play a dominant role in the biochemical conversion of cellulosic biomass to high-value biofuels. Anaerobic cellulolytic bacteria are capable of producing multicomplex catalytic subunits containing cell-adherent cellulases, hemicellulases, xylanases, and other glycoside hydrolases to facilitate the degradation of highly recalcitrant cellulose and other related plant cell wall polysaccharides. Clostridium thermocellum is a cellulosome producing bacterium that couples rapid reproduction rates to highly efficient degradation of crystalline cellulose. Herein, we have developed and applied a suite of difluoromethylphenyl aglycone, N-halogenated glycosylamine, and 2-deoxy-2-fluoroglycoside activity-based protein profiling (ABPP) probes to the direct labeling of the C. thermocellum cellulosomal secretome. These activity-based probes (ABPs) were synthesized with alkynes to harness the utility and multimodal possibilities of click chemistry, and to increase enzyme active site inclusion for LC-MS analysis. We directly analyzed ABP-labeled and unlabeled global MS data, revealing ABP selectivity for glycoside hydrolase (GH) enzymes, in addition to a large collection of integral cellulosome-containing proteins. By identifying reactivity and selectivity profiles for each ABP, we demonstrate our ability to widely profile the functional cellulose degrading machinery of the bacterium. Derivatization of the ABPs, including reactive groups, acetylation of the glycoside binding groups, and mono- and disaccharide binding groups, resulted in considerable variability in protein labeling. Our probe suite is applicable to aerobic and anaerobic microbial cellulose degrading systems, and facilitates a greater understanding of the organismal role associated with biofuel development. PMID:23176123

  15. Optimized Monitoring of Production of Cellulose Nanowhiskers from Opuntia ficus-indica (Nopal Cactus

    Directory of Open Access Journals (Sweden)

    Horacio Vieyra


    Full Text Available Preparation of cellulose nanowhiskers (CNWs has grown significantly because they are useful for a wide range of applications. Additional advantage in their design requires that they meet the following characteristics: nontoxicity, abundance, sustainability, renewability, and low cost. To address these requirements, nanowhiskers were prepared from Opuntia ficus-indica (nopal cellulose by acid hydrolysis. Monitoring the process of CNWs preparation is necessary to ensure maximum yield and purity of the end product. In this study, the cellulose preparation was monitored by analyzing microscopic morphology by SEM; the purity degree was determined by fluorescence microscopy as a novel and rapid technique, and FTIR spectroscopy was used for confirmation. The additional parameters that monitored the process were the crystallinity index by X-ray diffraction and the size of the particle by dynamic light scattering (DLS. Nopal cellulose was found to be comparable to commercial microcrystalline cellulose. The use of Opuntia ficus-indica is a viable alternative for the production of highly pure CNWs and the strategy to supervise the preparation process was rapid.

  16. Cellulose multilayer Membranes manufacture with Ionic liquid

    KAUST Repository

    Livazovic, Sara


    Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. By these methods porous supports could be easily coated with semi-crystalline cellulose. The membranes were hydrophilic with contact angles as low as 22.0°, molecular weight cut-off as low as 3000 g mol-1 with corresponding water permeance of 13.8 Lm−2 h−1 bar−1. Self-standing cellulose membranes were also manufactured without porous substrate, using only ionic liquid as green solvent. This membrane was insoluble in water, tetrahydrofuran, hexane, N,N-dimethylformamide, 1-methyl-2-pyrrolidinone and N,N-dimethylacetamide.

  17. Synthesis and characterization of antibacterial carboxymethyl cellulose/ZnO nanocomposite hydrogels. (United States)

    Yadollahi, Mehdi; Gholamali, Iman; Namazi, Hassan; Aghazadeh, Mohammad


    In this study, carboxymethyl cellulose/ZnO nanocomposite hydrogels have been synthesized through the in situ formation of ZnO nanoparticles within swollen carboxymethyl cellulose hydrogels. The formation of ZnO nanoparticles in the hydrogels was confirmed using X-ray diffraction, UV-vis spectroscopy and scanning electron microscopy (SEM) studies. SEM micrographs revealed the formation of ZnO nanoparticles with size range of 10-20 nm within the hydrogel matrix. The prepared nanocomposite hydrogels showed a pH and salt sensitive swelling behavior. The ZnO nanocomposite hydrogels have rather higher swelling in different aqueous solutions in comparison with neat hydrogel. The nanocomposite hydrogels demonstrated antibacterial effects against Escherichia coli and Staphylococcus aureus bacteria. The developed carboxymethyl cellulose/ZnO nanocomposite hydrogels can be used effectively for biomedical application.

  18. A novel approach for the preparation of nanocrystalline cellulose by using phosphotungstic acid. (United States)

    Liu, Yefei; Wang, Haisong; Yu, Guang; Yu, Qingxue; Li, Bin; Mu, Xindong


    In this work, a sustainable and green process to prepare nanocrystalline cellulose (NCC) from bleached hardwood pulp was demonstrated. Rod-like nanocrystalline cellulose with the size of 15-40 nm in width and hundreds of nanometers in length was obtained through H3PW12O40 (HPW)-catalyzed hydrolysis of bleached pulp fibers under the mild reaction conditions. Thermogravimetric analysis revealed that the resulting NCC exhibited much higher thermal stability than the partially sulfated NCC (prepared by sulfuric acid). In addition, the concentrated HPW could be easily recovered and recycled through the extraction with diethyl ether, and the recovered HPW could be reused for several rounds of cellulose hydrolysis without activity lost. These fundamental studies are of crucial importance for the development and application of NCC products/NCC-based biomaterials with good thermal stability.

  19. Isolation and characterization of microcrystalline cellulose from oil palm biomass residue. (United States)

    Mohamad Haafiz, M K; Eichhorn, S J; Hassan, Azman; Jawaid, M


    In this work, we successfully isolated microcrystalline cellulose (MCC) from oil palm empty fruit bunch (OPEFB) fiber-total chlorine free (TCF) pulp using acid hydrolysis method. TCF pulp bleaching carried out using an oxygen-ozone-hydrogen peroxide bleaching sequence. Fourier transform infrared (FT-IR) spectroscopy indicates that acid hydrolysis does not affect the chemical structure of the cellulosic fragments. The morphology of the hydrolyzed MCC was investigated using scanning electron microscopy (SEM), showing a compact structure and a rough surface. Furthermore, atomic force microscopy (AFM) image of the surface indicates the presence of spherical features. X-ray diffraction (XRD) shows that the MCC produced is a cellulose-I polymorph, with 87% crystallinity. The MCC obtained from OPEFB-pulp is shown to have a good thermal stability. The potential for a range of applications such as green nano biocomposites reinforced with this form of MCC and pharmaceutical tableting material is discussed.

  20. Preparation of biocompatible magnetite-carboxymethyl cellulose nanocomposite: Characterization of nanocomposite by FTIR, XRD, FESEM and TEM (United States)

    Habibi, Neda


    The preparation and characterization of magnetite-carboxymethyl cellulose nano-composite (M-CMC) material is described. Magnetite nano-particles were synthesized by a modified co-precipitation method using ferrous chloride tetrahydrate and ferric chloride hexahydrate in ammonium hydroxide solution. The M-CMC nano-composite particles were synthesized by embedding the magnetite nanoparticles inside carboxymethyl cellulose (CMC) using a freshly prepared mixture of Fe3O4 with CMC precursor. Morphology, particle size, and structural properties of magnetite-carboxymethyl cellulose nano-composite was accomplished using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR) and field emission scanning electron microscopy (FESEM) analysis. As a result, magnetite nano-particles with an average size of 35 nm were obtained. The biocompatible Fe3O4-carboxymethyl cellulose nano-composite particles obtained from the natural CMC polymers have a potential range of application in biomedical field.